app.rs

   1pub mod action;
   2mod callback_collection;
   3
   4use crate::{
   5    elements::ElementBox,
   6    executor::{self, Task},
   7    geometry::rect::RectF,
   8    keymap::{self, Binding, Keystroke},
   9    platform::{self, KeyDownEvent, Platform, PromptLevel, WindowOptions},
  10    presenter::Presenter,
  11    util::post_inc,
  12    AssetCache, AssetSource, ClipboardItem, FontCache, InputHandler, MouseButton, MouseRegionId,
  13    PathPromptOptions, TextLayoutCache,
  14};
  15pub use action::*;
  16use anyhow::{anyhow, Context, Result};
  17use callback_collection::CallbackCollection;
  18use collections::{btree_map, hash_map::Entry, BTreeMap, HashMap, HashSet, VecDeque};
  19use keymap::MatchResult;
  20use lazy_static::lazy_static;
  21use parking_lot::Mutex;
  22use platform::Event;
  23use postage::oneshot;
  24use smallvec::SmallVec;
  25use smol::prelude::*;
  26use std::{
  27    any::{type_name, Any, TypeId},
  28    cell::RefCell,
  29    fmt::{self, Debug},
  30    hash::{Hash, Hasher},
  31    marker::PhantomData,
  32    mem,
  33    ops::{Deref, DerefMut, Range},
  34    path::{Path, PathBuf},
  35    pin::Pin,
  36    rc::{self, Rc},
  37    sync::{Arc, Weak},
  38    time::Duration,
  39};
  40
  41use self::callback_collection::Mapping;
  42
  43pub trait Entity: 'static {
  44    type Event;
  45
  46    fn release(&mut self, _: &mut MutableAppContext) {}
  47    fn app_will_quit(
  48        &mut self,
  49        _: &mut MutableAppContext,
  50    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
  51        None
  52    }
  53}
  54
  55pub trait View: Entity + Sized {
  56    fn ui_name() -> &'static str;
  57    fn render(&mut self, cx: &mut RenderContext<'_, Self>) -> ElementBox;
  58    fn on_focus_in(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  59    fn on_focus_out(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  60    fn keymap_context(&self, _: &AppContext) -> keymap::Context {
  61        Self::default_keymap_context()
  62    }
  63    fn default_keymap_context() -> keymap::Context {
  64        let mut cx = keymap::Context::default();
  65        cx.set.insert(Self::ui_name().into());
  66        cx
  67    }
  68    fn debug_json(&self, _: &AppContext) -> serde_json::Value {
  69        serde_json::Value::Null
  70    }
  71
  72    fn text_for_range(&self, _: Range<usize>, _: &AppContext) -> Option<String> {
  73        None
  74    }
  75    fn selected_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
  76        None
  77    }
  78    fn marked_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
  79        None
  80    }
  81    fn unmark_text(&mut self, _: &mut ViewContext<Self>) {}
  82    fn replace_text_in_range(
  83        &mut self,
  84        _: Option<Range<usize>>,
  85        _: &str,
  86        _: &mut ViewContext<Self>,
  87    ) {
  88    }
  89    fn replace_and_mark_text_in_range(
  90        &mut self,
  91        _: Option<Range<usize>>,
  92        _: &str,
  93        _: Option<Range<usize>>,
  94        _: &mut ViewContext<Self>,
  95    ) {
  96    }
  97}
  98
  99pub trait ReadModel {
 100    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T;
 101}
 102
 103pub trait ReadModelWith {
 104    fn read_model_with<E: Entity, T>(
 105        &self,
 106        handle: &ModelHandle<E>,
 107        read: &mut dyn FnMut(&E, &AppContext) -> T,
 108    ) -> T;
 109}
 110
 111pub trait UpdateModel {
 112    fn update_model<T: Entity, O>(
 113        &mut self,
 114        handle: &ModelHandle<T>,
 115        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
 116    ) -> O;
 117}
 118
 119pub trait UpgradeModelHandle {
 120    fn upgrade_model_handle<T: Entity>(
 121        &self,
 122        handle: &WeakModelHandle<T>,
 123    ) -> Option<ModelHandle<T>>;
 124
 125    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool;
 126
 127    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle>;
 128}
 129
 130pub trait UpgradeViewHandle {
 131    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>>;
 132
 133    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle>;
 134}
 135
 136pub trait ReadView {
 137    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T;
 138}
 139
 140pub trait ReadViewWith {
 141    fn read_view_with<V, T>(
 142        &self,
 143        handle: &ViewHandle<V>,
 144        read: &mut dyn FnMut(&V, &AppContext) -> T,
 145    ) -> T
 146    where
 147        V: View;
 148}
 149
 150pub trait UpdateView {
 151    fn update_view<T, S>(
 152        &mut self,
 153        handle: &ViewHandle<T>,
 154        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 155    ) -> S
 156    where
 157        T: View;
 158}
 159
 160pub struct Menu<'a> {
 161    pub name: &'a str,
 162    pub items: Vec<MenuItem<'a>>,
 163}
 164
 165pub enum MenuItem<'a> {
 166    Separator,
 167    Submenu(Menu<'a>),
 168    Action {
 169        name: &'a str,
 170        action: Box<dyn Action>,
 171    },
 172}
 173
 174#[derive(Clone)]
 175pub struct App(Rc<RefCell<MutableAppContext>>);
 176
 177#[derive(Clone)]
 178pub struct AsyncAppContext(Rc<RefCell<MutableAppContext>>);
 179
 180#[cfg(any(test, feature = "test-support"))]
 181pub struct TestAppContext {
 182    cx: Rc<RefCell<MutableAppContext>>,
 183    foreground_platform: Rc<platform::test::ForegroundPlatform>,
 184    condition_duration: Option<Duration>,
 185}
 186
 187pub struct WindowInputHandler {
 188    app: Rc<RefCell<MutableAppContext>>,
 189    window_id: usize,
 190}
 191
 192impl App {
 193    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 194        let platform = platform::current::platform();
 195        let foreground_platform = platform::current::foreground_platform();
 196        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 197        let app = Self(Rc::new(RefCell::new(MutableAppContext::new(
 198            foreground,
 199            Arc::new(executor::Background::new()),
 200            platform.clone(),
 201            foreground_platform.clone(),
 202            Arc::new(FontCache::new(platform.fonts())),
 203            Default::default(),
 204            asset_source,
 205        ))));
 206
 207        foreground_platform.on_quit(Box::new({
 208            let cx = app.0.clone();
 209            move || {
 210                cx.borrow_mut().quit();
 211            }
 212        }));
 213        foreground_platform.on_will_open_menu(Box::new({
 214            let cx = app.0.clone();
 215            move || {
 216                let mut cx = cx.borrow_mut();
 217                cx.keystroke_matcher.clear_pending();
 218            }
 219        }));
 220        foreground_platform.on_validate_menu_command(Box::new({
 221            let cx = app.0.clone();
 222            move |action| {
 223                let cx = cx.borrow_mut();
 224                !cx.keystroke_matcher.has_pending_keystrokes() && cx.is_action_available(action)
 225            }
 226        }));
 227        foreground_platform.on_menu_command(Box::new({
 228            let cx = app.0.clone();
 229            move |action| {
 230                let mut cx = cx.borrow_mut();
 231                if let Some(key_window_id) = cx.cx.platform.key_window_id() {
 232                    if let Some(view_id) = cx.focused_view_id(key_window_id) {
 233                        cx.handle_dispatch_action_from_effect(key_window_id, Some(view_id), action);
 234                        return;
 235                    }
 236                }
 237                cx.dispatch_global_action_any(action);
 238            }
 239        }));
 240
 241        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 242        Ok(app)
 243    }
 244
 245    pub fn background(&self) -> Arc<executor::Background> {
 246        self.0.borrow().background().clone()
 247    }
 248
 249    pub fn on_become_active<F>(self, mut callback: F) -> Self
 250    where
 251        F: 'static + FnMut(&mut MutableAppContext),
 252    {
 253        let cx = self.0.clone();
 254        self.0
 255            .borrow_mut()
 256            .foreground_platform
 257            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 258        self
 259    }
 260
 261    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 262    where
 263        F: 'static + FnMut(&mut MutableAppContext),
 264    {
 265        let cx = self.0.clone();
 266        self.0
 267            .borrow_mut()
 268            .foreground_platform
 269            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 270        self
 271    }
 272
 273    pub fn on_quit<F>(&mut self, mut callback: F) -> &mut Self
 274    where
 275        F: 'static + FnMut(&mut MutableAppContext),
 276    {
 277        let cx = self.0.clone();
 278        self.0
 279            .borrow_mut()
 280            .foreground_platform
 281            .on_quit(Box::new(move || callback(&mut *cx.borrow_mut())));
 282        self
 283    }
 284
 285    pub fn on_event<F>(&mut self, mut callback: F) -> &mut Self
 286    where
 287        F: 'static + FnMut(Event, &mut MutableAppContext) -> bool,
 288    {
 289        let cx = self.0.clone();
 290        self.0
 291            .borrow_mut()
 292            .foreground_platform
 293            .on_event(Box::new(move |event| {
 294                callback(event, &mut *cx.borrow_mut())
 295            }));
 296        self
 297    }
 298
 299    pub fn on_open_urls<F>(&mut self, mut callback: F) -> &mut Self
 300    where
 301        F: 'static + FnMut(Vec<String>, &mut MutableAppContext),
 302    {
 303        let cx = self.0.clone();
 304        self.0
 305            .borrow_mut()
 306            .foreground_platform
 307            .on_open_urls(Box::new(move |paths| {
 308                callback(paths, &mut *cx.borrow_mut())
 309            }));
 310        self
 311    }
 312
 313    pub fn run<F>(self, on_finish_launching: F)
 314    where
 315        F: 'static + FnOnce(&mut MutableAppContext),
 316    {
 317        let platform = self.0.borrow().foreground_platform.clone();
 318        platform.run(Box::new(move || {
 319            let mut cx = self.0.borrow_mut();
 320            let cx = &mut *cx;
 321            crate::views::init(cx);
 322            on_finish_launching(cx);
 323        }))
 324    }
 325
 326    pub fn platform(&self) -> Arc<dyn Platform> {
 327        self.0.borrow().platform()
 328    }
 329
 330    pub fn font_cache(&self) -> Arc<FontCache> {
 331        self.0.borrow().cx.font_cache.clone()
 332    }
 333
 334    fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 335        let mut state = self.0.borrow_mut();
 336        let result = state.update(callback);
 337        state.pending_notifications.clear();
 338        result
 339    }
 340}
 341
 342impl WindowInputHandler {
 343    fn read_focused_view<T, F>(&self, f: F) -> Option<T>
 344    where
 345        F: FnOnce(&dyn AnyView, &AppContext) -> T,
 346    {
 347        // Input-related application hooks are sometimes called by the OS during
 348        // a call to a window-manipulation API, like prompting the user for file
 349        // paths. In that case, the AppContext will already be borrowed, so any
 350        // InputHandler methods need to fail gracefully.
 351        //
 352        // See https://github.com/zed-industries/feedback/issues/444
 353        let app = self.app.try_borrow().ok()?;
 354
 355        let view_id = app.focused_view_id(self.window_id)?;
 356        let view = app.cx.views.get(&(self.window_id, view_id))?;
 357        let result = f(view.as_ref(), &app);
 358        Some(result)
 359    }
 360
 361    fn update_focused_view<T, F>(&mut self, f: F) -> Option<T>
 362    where
 363        F: FnOnce(usize, usize, &mut dyn AnyView, &mut MutableAppContext) -> T,
 364    {
 365        let mut app = self.app.try_borrow_mut().ok()?;
 366        app.update(|app| {
 367            let view_id = app.focused_view_id(self.window_id)?;
 368            let mut view = app.cx.views.remove(&(self.window_id, view_id))?;
 369            let result = f(self.window_id, view_id, view.as_mut(), &mut *app);
 370            app.cx.views.insert((self.window_id, view_id), view);
 371            Some(result)
 372        })
 373    }
 374}
 375
 376impl InputHandler for WindowInputHandler {
 377    fn text_for_range(&self, range: Range<usize>) -> Option<String> {
 378        self.read_focused_view(|view, cx| view.text_for_range(range.clone(), cx))
 379            .flatten()
 380    }
 381
 382    fn selected_text_range(&self) -> Option<Range<usize>> {
 383        self.read_focused_view(|view, cx| view.selected_text_range(cx))
 384            .flatten()
 385    }
 386
 387    fn replace_text_in_range(&mut self, range: Option<Range<usize>>, text: &str) {
 388        self.update_focused_view(|window_id, view_id, view, cx| {
 389            view.replace_text_in_range(range, text, cx, window_id, view_id);
 390        });
 391    }
 392
 393    fn marked_text_range(&self) -> Option<Range<usize>> {
 394        self.read_focused_view(|view, cx| view.marked_text_range(cx))
 395            .flatten()
 396    }
 397
 398    fn unmark_text(&mut self) {
 399        self.update_focused_view(|window_id, view_id, view, cx| {
 400            view.unmark_text(cx, window_id, view_id);
 401        });
 402    }
 403
 404    fn replace_and_mark_text_in_range(
 405        &mut self,
 406        range: Option<Range<usize>>,
 407        new_text: &str,
 408        new_selected_range: Option<Range<usize>>,
 409    ) {
 410        self.update_focused_view(|window_id, view_id, view, cx| {
 411            view.replace_and_mark_text_in_range(
 412                range,
 413                new_text,
 414                new_selected_range,
 415                cx,
 416                window_id,
 417                view_id,
 418            );
 419        });
 420    }
 421
 422    fn rect_for_range(&self, range_utf16: Range<usize>) -> Option<RectF> {
 423        let app = self.app.borrow();
 424        let (presenter, _) = app.presenters_and_platform_windows.get(&self.window_id)?;
 425        let presenter = presenter.borrow();
 426        presenter.rect_for_text_range(range_utf16, &app)
 427    }
 428}
 429
 430#[cfg(any(test, feature = "test-support"))]
 431impl TestAppContext {
 432    pub fn new(
 433        foreground_platform: Rc<platform::test::ForegroundPlatform>,
 434        platform: Arc<dyn Platform>,
 435        foreground: Rc<executor::Foreground>,
 436        background: Arc<executor::Background>,
 437        font_cache: Arc<FontCache>,
 438        leak_detector: Arc<Mutex<LeakDetector>>,
 439        first_entity_id: usize,
 440    ) -> Self {
 441        let mut cx = MutableAppContext::new(
 442            foreground,
 443            background,
 444            platform,
 445            foreground_platform.clone(),
 446            font_cache,
 447            RefCounts {
 448                #[cfg(any(test, feature = "test-support"))]
 449                leak_detector,
 450                ..Default::default()
 451            },
 452            (),
 453        );
 454        cx.next_entity_id = first_entity_id;
 455        let cx = TestAppContext {
 456            cx: Rc::new(RefCell::new(cx)),
 457            foreground_platform,
 458            condition_duration: None,
 459        };
 460        cx.cx.borrow_mut().weak_self = Some(Rc::downgrade(&cx.cx));
 461        cx
 462    }
 463
 464    pub fn dispatch_action<A: Action>(&self, window_id: usize, action: A) {
 465        let mut cx = self.cx.borrow_mut();
 466        if let Some(view_id) = cx.focused_view_id(window_id) {
 467            cx.handle_dispatch_action_from_effect(window_id, Some(view_id), &action);
 468        }
 469    }
 470
 471    pub fn dispatch_global_action<A: Action>(&self, action: A) {
 472        self.cx.borrow_mut().dispatch_global_action(action);
 473    }
 474
 475    pub fn dispatch_keystroke(&mut self, window_id: usize, keystroke: Keystroke, is_held: bool) {
 476        let handled = self.cx.borrow_mut().update(|cx| {
 477            let presenter = cx
 478                .presenters_and_platform_windows
 479                .get(&window_id)
 480                .unwrap()
 481                .0
 482                .clone();
 483
 484            if cx.dispatch_keystroke(window_id, &keystroke) {
 485                return true;
 486            }
 487
 488            if presenter.borrow_mut().dispatch_event(
 489                Event::KeyDown(KeyDownEvent {
 490                    keystroke: keystroke.clone(),
 491                    is_held,
 492                }),
 493                false,
 494                cx,
 495            ) {
 496                return true;
 497            }
 498
 499            false
 500        });
 501
 502        if !handled && !keystroke.cmd && !keystroke.ctrl {
 503            WindowInputHandler {
 504                app: self.cx.clone(),
 505                window_id,
 506            }
 507            .replace_text_in_range(None, &keystroke.key)
 508        }
 509    }
 510
 511    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 512    where
 513        T: Entity,
 514        F: FnOnce(&mut ModelContext<T>) -> T,
 515    {
 516        self.cx.borrow_mut().add_model(build_model)
 517    }
 518
 519    pub fn add_window<T, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<T>)
 520    where
 521        T: View,
 522        F: FnOnce(&mut ViewContext<T>) -> T,
 523    {
 524        let (window_id, view) = self
 525            .cx
 526            .borrow_mut()
 527            .add_window(Default::default(), build_root_view);
 528        self.simulate_window_activation(Some(window_id));
 529        (window_id, view)
 530    }
 531
 532    pub fn add_view<T, F>(
 533        &mut self,
 534        parent_handle: impl Into<AnyViewHandle>,
 535        build_view: F,
 536    ) -> ViewHandle<T>
 537    where
 538        T: View,
 539        F: FnOnce(&mut ViewContext<T>) -> T,
 540    {
 541        self.cx.borrow_mut().add_view(parent_handle, build_view)
 542    }
 543
 544    pub fn window_ids(&self) -> Vec<usize> {
 545        self.cx.borrow().window_ids().collect()
 546    }
 547
 548    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
 549        self.cx.borrow().root_view(window_id)
 550    }
 551
 552    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 553        callback(self.cx.borrow().as_ref())
 554    }
 555
 556    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 557        let mut state = self.cx.borrow_mut();
 558        // Don't increment pending flushes in order for effects to be flushed before the callback
 559        // completes, which is helpful in tests.
 560        let result = callback(&mut *state);
 561        // Flush effects after the callback just in case there are any. This can happen in edge
 562        // cases such as the closure dropping handles.
 563        state.flush_effects();
 564        result
 565    }
 566
 567    pub fn render<F, V, T>(&mut self, handle: &ViewHandle<V>, f: F) -> T
 568    where
 569        F: FnOnce(&mut V, &mut RenderContext<V>) -> T,
 570        V: View,
 571    {
 572        handle.update(&mut *self.cx.borrow_mut(), |view, cx| {
 573            let mut render_cx = RenderContext {
 574                app: cx,
 575                window_id: handle.window_id(),
 576                view_id: handle.id(),
 577                view_type: PhantomData,
 578                titlebar_height: 0.,
 579                hovered_region_ids: Default::default(),
 580                clicked_region_ids: None,
 581                refreshing: false,
 582            };
 583            f(view, &mut render_cx)
 584        })
 585    }
 586
 587    pub fn to_async(&self) -> AsyncAppContext {
 588        AsyncAppContext(self.cx.clone())
 589    }
 590
 591    pub fn font_cache(&self) -> Arc<FontCache> {
 592        self.cx.borrow().cx.font_cache.clone()
 593    }
 594
 595    pub fn foreground_platform(&self) -> Rc<platform::test::ForegroundPlatform> {
 596        self.foreground_platform.clone()
 597    }
 598
 599    pub fn platform(&self) -> Arc<dyn platform::Platform> {
 600        self.cx.borrow().cx.platform.clone()
 601    }
 602
 603    pub fn foreground(&self) -> Rc<executor::Foreground> {
 604        self.cx.borrow().foreground().clone()
 605    }
 606
 607    pub fn background(&self) -> Arc<executor::Background> {
 608        self.cx.borrow().background().clone()
 609    }
 610
 611    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 612    where
 613        F: FnOnce(AsyncAppContext) -> Fut,
 614        Fut: 'static + Future<Output = T>,
 615        T: 'static,
 616    {
 617        let foreground = self.foreground();
 618        let future = f(self.to_async());
 619        let cx = self.to_async();
 620        foreground.spawn(async move {
 621            let result = future.await;
 622            cx.0.borrow_mut().flush_effects();
 623            result
 624        })
 625    }
 626
 627    pub fn simulate_new_path_selection(&self, result: impl FnOnce(PathBuf) -> Option<PathBuf>) {
 628        self.foreground_platform.simulate_new_path_selection(result);
 629    }
 630
 631    pub fn did_prompt_for_new_path(&self) -> bool {
 632        self.foreground_platform.as_ref().did_prompt_for_new_path()
 633    }
 634
 635    pub fn simulate_prompt_answer(&self, window_id: usize, answer: usize) {
 636        use postage::prelude::Sink as _;
 637
 638        let mut done_tx = self
 639            .window_mut(window_id)
 640            .pending_prompts
 641            .borrow_mut()
 642            .pop_front()
 643            .expect("prompt was not called");
 644        let _ = done_tx.try_send(answer);
 645    }
 646
 647    pub fn has_pending_prompt(&self, window_id: usize) -> bool {
 648        let window = self.window_mut(window_id);
 649        let prompts = window.pending_prompts.borrow_mut();
 650        !prompts.is_empty()
 651    }
 652
 653    pub fn current_window_title(&self, window_id: usize) -> Option<String> {
 654        self.window_mut(window_id).title.clone()
 655    }
 656
 657    pub fn simulate_window_close(&self, window_id: usize) -> bool {
 658        let handler = self.window_mut(window_id).should_close_handler.take();
 659        if let Some(mut handler) = handler {
 660            let should_close = handler();
 661            self.window_mut(window_id).should_close_handler = Some(handler);
 662            should_close
 663        } else {
 664            false
 665        }
 666    }
 667
 668    pub fn simulate_window_activation(&self, to_activate: Option<usize>) {
 669        let mut handlers = BTreeMap::new();
 670        {
 671            let mut cx = self.cx.borrow_mut();
 672            for (window_id, (_, window)) in &mut cx.presenters_and_platform_windows {
 673                let window = window
 674                    .as_any_mut()
 675                    .downcast_mut::<platform::test::Window>()
 676                    .unwrap();
 677                handlers.insert(
 678                    *window_id,
 679                    mem::take(&mut window.active_status_change_handlers),
 680                );
 681            }
 682        };
 683        let mut handlers = handlers.into_iter().collect::<Vec<_>>();
 684        handlers.sort_unstable_by_key(|(window_id, _)| Some(*window_id) == to_activate);
 685
 686        for (window_id, mut window_handlers) in handlers {
 687            for window_handler in &mut window_handlers {
 688                window_handler(Some(window_id) == to_activate);
 689            }
 690
 691            self.window_mut(window_id)
 692                .active_status_change_handlers
 693                .extend(window_handlers);
 694        }
 695    }
 696
 697    pub fn is_window_edited(&self, window_id: usize) -> bool {
 698        self.window_mut(window_id).edited
 699    }
 700
 701    pub fn leak_detector(&self) -> Arc<Mutex<LeakDetector>> {
 702        self.cx.borrow().leak_detector()
 703    }
 704
 705    pub fn assert_dropped(&self, handle: impl WeakHandle) {
 706        self.cx
 707            .borrow()
 708            .leak_detector()
 709            .lock()
 710            .assert_dropped(handle.id())
 711    }
 712
 713    fn window_mut(&self, window_id: usize) -> std::cell::RefMut<platform::test::Window> {
 714        std::cell::RefMut::map(self.cx.borrow_mut(), |state| {
 715            let (_, window) = state
 716                .presenters_and_platform_windows
 717                .get_mut(&window_id)
 718                .unwrap();
 719            let test_window = window
 720                .as_any_mut()
 721                .downcast_mut::<platform::test::Window>()
 722                .unwrap();
 723            test_window
 724        })
 725    }
 726
 727    pub fn set_condition_duration(&mut self, duration: Option<Duration>) {
 728        self.condition_duration = duration;
 729    }
 730
 731    pub fn condition_duration(&self) -> Duration {
 732        self.condition_duration.unwrap_or_else(|| {
 733            if std::env::var("CI").is_ok() {
 734                Duration::from_secs(2)
 735            } else {
 736                Duration::from_millis(500)
 737            }
 738        })
 739    }
 740
 741    pub fn assert_clipboard_content(&mut self, expected_content: Option<&str>) {
 742        self.update(|cx| {
 743            let actual_content = cx.read_from_clipboard().map(|item| item.text().to_owned());
 744            let expected_content = expected_content.map(|content| content.to_owned());
 745            assert_eq!(actual_content, expected_content);
 746        })
 747    }
 748}
 749
 750impl AsyncAppContext {
 751    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 752    where
 753        F: FnOnce(AsyncAppContext) -> Fut,
 754        Fut: 'static + Future<Output = T>,
 755        T: 'static,
 756    {
 757        self.0.borrow().foreground.spawn(f(self.clone()))
 758    }
 759
 760    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 761        callback(self.0.borrow().as_ref())
 762    }
 763
 764    pub fn update<T, F: FnOnce(&mut MutableAppContext) -> T>(&mut self, callback: F) -> T {
 765        self.0.borrow_mut().update(callback)
 766    }
 767
 768    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 769    where
 770        T: Entity,
 771        F: FnOnce(&mut ModelContext<T>) -> T,
 772    {
 773        self.update(|cx| cx.add_model(build_model))
 774    }
 775
 776    pub fn add_window<T, F>(
 777        &mut self,
 778        window_options: WindowOptions,
 779        build_root_view: F,
 780    ) -> (usize, ViewHandle<T>)
 781    where
 782        T: View,
 783        F: FnOnce(&mut ViewContext<T>) -> T,
 784    {
 785        self.update(|cx| cx.add_window(window_options, build_root_view))
 786    }
 787
 788    pub fn platform(&self) -> Arc<dyn Platform> {
 789        self.0.borrow().platform()
 790    }
 791
 792    pub fn foreground(&self) -> Rc<executor::Foreground> {
 793        self.0.borrow().foreground.clone()
 794    }
 795
 796    pub fn background(&self) -> Arc<executor::Background> {
 797        self.0.borrow().cx.background.clone()
 798    }
 799}
 800
 801impl UpdateModel for AsyncAppContext {
 802    fn update_model<E: Entity, O>(
 803        &mut self,
 804        handle: &ModelHandle<E>,
 805        update: &mut dyn FnMut(&mut E, &mut ModelContext<E>) -> O,
 806    ) -> O {
 807        self.0.borrow_mut().update_model(handle, update)
 808    }
 809}
 810
 811impl UpgradeModelHandle for AsyncAppContext {
 812    fn upgrade_model_handle<T: Entity>(
 813        &self,
 814        handle: &WeakModelHandle<T>,
 815    ) -> Option<ModelHandle<T>> {
 816        self.0.borrow().upgrade_model_handle(handle)
 817    }
 818
 819    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
 820        self.0.borrow().model_handle_is_upgradable(handle)
 821    }
 822
 823    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
 824        self.0.borrow().upgrade_any_model_handle(handle)
 825    }
 826}
 827
 828impl UpgradeViewHandle for AsyncAppContext {
 829    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
 830        self.0.borrow_mut().upgrade_view_handle(handle)
 831    }
 832
 833    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
 834        self.0.borrow_mut().upgrade_any_view_handle(handle)
 835    }
 836}
 837
 838impl ReadModelWith for AsyncAppContext {
 839    fn read_model_with<E: Entity, T>(
 840        &self,
 841        handle: &ModelHandle<E>,
 842        read: &mut dyn FnMut(&E, &AppContext) -> T,
 843    ) -> T {
 844        let cx = self.0.borrow();
 845        let cx = cx.as_ref();
 846        read(handle.read(cx), cx)
 847    }
 848}
 849
 850impl UpdateView for AsyncAppContext {
 851    fn update_view<T, S>(
 852        &mut self,
 853        handle: &ViewHandle<T>,
 854        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 855    ) -> S
 856    where
 857        T: View,
 858    {
 859        self.0.borrow_mut().update_view(handle, update)
 860    }
 861}
 862
 863impl ReadViewWith for AsyncAppContext {
 864    fn read_view_with<V, T>(
 865        &self,
 866        handle: &ViewHandle<V>,
 867        read: &mut dyn FnMut(&V, &AppContext) -> T,
 868    ) -> T
 869    where
 870        V: View,
 871    {
 872        let cx = self.0.borrow();
 873        let cx = cx.as_ref();
 874        read(handle.read(cx), cx)
 875    }
 876}
 877
 878#[cfg(any(test, feature = "test-support"))]
 879impl UpdateModel for TestAppContext {
 880    fn update_model<T: Entity, O>(
 881        &mut self,
 882        handle: &ModelHandle<T>,
 883        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
 884    ) -> O {
 885        self.cx.borrow_mut().update_model(handle, update)
 886    }
 887}
 888
 889#[cfg(any(test, feature = "test-support"))]
 890impl ReadModelWith for TestAppContext {
 891    fn read_model_with<E: Entity, T>(
 892        &self,
 893        handle: &ModelHandle<E>,
 894        read: &mut dyn FnMut(&E, &AppContext) -> T,
 895    ) -> T {
 896        let cx = self.cx.borrow();
 897        let cx = cx.as_ref();
 898        read(handle.read(cx), cx)
 899    }
 900}
 901
 902#[cfg(any(test, feature = "test-support"))]
 903impl UpdateView for TestAppContext {
 904    fn update_view<T, S>(
 905        &mut self,
 906        handle: &ViewHandle<T>,
 907        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 908    ) -> S
 909    where
 910        T: View,
 911    {
 912        self.cx.borrow_mut().update_view(handle, update)
 913    }
 914}
 915
 916#[cfg(any(test, feature = "test-support"))]
 917impl ReadViewWith for TestAppContext {
 918    fn read_view_with<V, T>(
 919        &self,
 920        handle: &ViewHandle<V>,
 921        read: &mut dyn FnMut(&V, &AppContext) -> T,
 922    ) -> T
 923    where
 924        V: View,
 925    {
 926        let cx = self.cx.borrow();
 927        let cx = cx.as_ref();
 928        read(handle.read(cx), cx)
 929    }
 930}
 931
 932type ActionCallback =
 933    dyn FnMut(&mut dyn AnyView, &dyn Action, &mut MutableAppContext, usize, usize);
 934type GlobalActionCallback = dyn FnMut(&dyn Action, &mut MutableAppContext);
 935
 936type SubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut MutableAppContext) -> bool>;
 937type GlobalSubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut MutableAppContext)>;
 938type ObservationCallback = Box<dyn FnMut(&mut MutableAppContext) -> bool>;
 939type FocusObservationCallback = Box<dyn FnMut(bool, &mut MutableAppContext) -> bool>;
 940type GlobalObservationCallback = Box<dyn FnMut(&mut MutableAppContext)>;
 941type ReleaseObservationCallback = Box<dyn FnOnce(&dyn Any, &mut MutableAppContext)>;
 942type ActionObservationCallback = Box<dyn FnMut(TypeId, &mut MutableAppContext)>;
 943type WindowActivationCallback = Box<dyn FnMut(bool, &mut MutableAppContext) -> bool>;
 944type WindowFullscreenCallback = Box<dyn FnMut(bool, &mut MutableAppContext) -> bool>;
 945type DeserializeActionCallback = fn(json: &str) -> anyhow::Result<Box<dyn Action>>;
 946type WindowShouldCloseSubscriptionCallback = Box<dyn FnMut(&mut MutableAppContext) -> bool>;
 947
 948pub struct MutableAppContext {
 949    weak_self: Option<rc::Weak<RefCell<Self>>>,
 950    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 951    assets: Arc<AssetCache>,
 952    cx: AppContext,
 953    action_deserializers: HashMap<&'static str, (TypeId, DeserializeActionCallback)>,
 954    capture_actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 955    actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 956    global_actions: HashMap<TypeId, Box<GlobalActionCallback>>,
 957    keystroke_matcher: keymap::Matcher,
 958    next_entity_id: usize,
 959    next_window_id: usize,
 960    next_subscription_id: usize,
 961    frame_count: usize,
 962
 963    focus_observations: CallbackCollection<usize, FocusObservationCallback>,
 964    global_subscriptions: CallbackCollection<TypeId, GlobalSubscriptionCallback>,
 965    global_observations: CallbackCollection<TypeId, GlobalObservationCallback>,
 966    subscriptions: CallbackCollection<usize, SubscriptionCallback>,
 967    observations: CallbackCollection<usize, ObservationCallback>,
 968    window_activation_observations: CallbackCollection<usize, WindowActivationCallback>,
 969    window_fullscreen_observations: CallbackCollection<usize, WindowFullscreenCallback>,
 970
 971    release_observations: Arc<Mutex<HashMap<usize, BTreeMap<usize, ReleaseObservationCallback>>>>,
 972    action_dispatch_observations: Arc<Mutex<BTreeMap<usize, ActionObservationCallback>>>,
 973
 974    #[allow(clippy::type_complexity)]
 975    presenters_and_platform_windows:
 976        HashMap<usize, (Rc<RefCell<Presenter>>, Box<dyn platform::Window>)>,
 977    foreground: Rc<executor::Foreground>,
 978    pending_effects: VecDeque<Effect>,
 979    pending_focus_index: Option<usize>,
 980    pending_notifications: HashSet<usize>,
 981    pending_global_notifications: HashSet<TypeId>,
 982    pending_flushes: usize,
 983    flushing_effects: bool,
 984    halt_action_dispatch: bool,
 985}
 986
 987impl MutableAppContext {
 988    fn new(
 989        foreground: Rc<executor::Foreground>,
 990        background: Arc<executor::Background>,
 991        platform: Arc<dyn platform::Platform>,
 992        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 993        font_cache: Arc<FontCache>,
 994        ref_counts: RefCounts,
 995        asset_source: impl AssetSource,
 996    ) -> Self {
 997        Self {
 998            weak_self: None,
 999            foreground_platform,
1000            assets: Arc::new(AssetCache::new(asset_source)),
1001            cx: AppContext {
1002                models: Default::default(),
1003                views: Default::default(),
1004                parents: Default::default(),
1005                windows: Default::default(),
1006                globals: Default::default(),
1007                element_states: Default::default(),
1008                ref_counts: Arc::new(Mutex::new(ref_counts)),
1009                background,
1010                font_cache,
1011                platform,
1012            },
1013            action_deserializers: Default::default(),
1014            capture_actions: Default::default(),
1015            actions: Default::default(),
1016            global_actions: Default::default(),
1017            keystroke_matcher: keymap::Matcher::default(),
1018            next_entity_id: 0,
1019            next_window_id: 0,
1020            next_subscription_id: 0,
1021            frame_count: 0,
1022            subscriptions: Default::default(),
1023            global_subscriptions: Default::default(),
1024            observations: Default::default(),
1025            focus_observations: Default::default(),
1026            release_observations: Default::default(),
1027            global_observations: Default::default(),
1028            window_activation_observations: Default::default(),
1029            window_fullscreen_observations: Default::default(),
1030            action_dispatch_observations: Default::default(),
1031            presenters_and_platform_windows: Default::default(),
1032            foreground,
1033            pending_effects: VecDeque::new(),
1034            pending_focus_index: None,
1035            pending_notifications: Default::default(),
1036            pending_global_notifications: Default::default(),
1037            pending_flushes: 0,
1038            flushing_effects: false,
1039            halt_action_dispatch: false,
1040        }
1041    }
1042
1043    pub fn upgrade(&self) -> App {
1044        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
1045    }
1046
1047    pub fn quit(&mut self) {
1048        let mut futures = Vec::new();
1049        for model_id in self.cx.models.keys().copied().collect::<Vec<_>>() {
1050            let mut model = self.cx.models.remove(&model_id).unwrap();
1051            futures.extend(model.app_will_quit(self));
1052            self.cx.models.insert(model_id, model);
1053        }
1054
1055        for view_id in self.cx.views.keys().copied().collect::<Vec<_>>() {
1056            let mut view = self.cx.views.remove(&view_id).unwrap();
1057            futures.extend(view.app_will_quit(self));
1058            self.cx.views.insert(view_id, view);
1059        }
1060
1061        self.remove_all_windows();
1062
1063        let futures = futures::future::join_all(futures);
1064        if self
1065            .background
1066            .block_with_timeout(Duration::from_millis(100), futures)
1067            .is_err()
1068        {
1069            log::error!("timed out waiting on app_will_quit");
1070        }
1071    }
1072
1073    pub fn remove_all_windows(&mut self) {
1074        for (window_id, _) in self.cx.windows.drain() {
1075            self.presenters_and_platform_windows.remove(&window_id);
1076        }
1077        self.flush_effects();
1078    }
1079
1080    pub fn platform(&self) -> Arc<dyn platform::Platform> {
1081        self.cx.platform.clone()
1082    }
1083
1084    pub fn font_cache(&self) -> &Arc<FontCache> {
1085        &self.cx.font_cache
1086    }
1087
1088    pub fn foreground(&self) -> &Rc<executor::Foreground> {
1089        &self.foreground
1090    }
1091
1092    pub fn background(&self) -> &Arc<executor::Background> {
1093        &self.cx.background
1094    }
1095
1096    pub fn debug_elements(&self, window_id: usize) -> Option<crate::json::Value> {
1097        self.presenters_and_platform_windows
1098            .get(&window_id)
1099            .and_then(|(presenter, _)| presenter.borrow().debug_elements(self))
1100    }
1101
1102    pub fn deserialize_action(
1103        &self,
1104        name: &str,
1105        argument: Option<&str>,
1106    ) -> Result<Box<dyn Action>> {
1107        let callback = self
1108            .action_deserializers
1109            .get(name)
1110            .ok_or_else(|| anyhow!("unknown action {}", name))?
1111            .1;
1112        callback(argument.unwrap_or("{}"))
1113            .with_context(|| format!("invalid data for action {}", name))
1114    }
1115
1116    pub fn add_action<A, V, F>(&mut self, handler: F)
1117    where
1118        A: Action,
1119        V: View,
1120        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
1121    {
1122        self.add_action_internal(handler, false)
1123    }
1124
1125    pub fn capture_action<A, V, F>(&mut self, handler: F)
1126    where
1127        A: Action,
1128        V: View,
1129        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
1130    {
1131        self.add_action_internal(handler, true)
1132    }
1133
1134    fn add_action_internal<A, V, F>(&mut self, mut handler: F, capture: bool)
1135    where
1136        A: Action,
1137        V: View,
1138        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
1139    {
1140        let handler = Box::new(
1141            move |view: &mut dyn AnyView,
1142                  action: &dyn Action,
1143                  cx: &mut MutableAppContext,
1144                  window_id: usize,
1145                  view_id: usize| {
1146                let action = action.as_any().downcast_ref().unwrap();
1147                let mut cx = ViewContext::new(cx, window_id, view_id);
1148                handler(
1149                    view.as_any_mut()
1150                        .downcast_mut()
1151                        .expect("downcast is type safe"),
1152                    action,
1153                    &mut cx,
1154                );
1155            },
1156        );
1157
1158        self.action_deserializers
1159            .entry(A::qualified_name())
1160            .or_insert((TypeId::of::<A>(), A::from_json_str));
1161
1162        let actions = if capture {
1163            &mut self.capture_actions
1164        } else {
1165            &mut self.actions
1166        };
1167
1168        actions
1169            .entry(TypeId::of::<V>())
1170            .or_default()
1171            .entry(TypeId::of::<A>())
1172            .or_default()
1173            .push(handler);
1174    }
1175
1176    pub fn add_async_action<A, V, F>(&mut self, mut handler: F)
1177    where
1178        A: Action,
1179        V: View,
1180        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> Option<Task<Result<()>>>,
1181    {
1182        self.add_action(move |view, action, cx| {
1183            if let Some(task) = handler(view, action, cx) {
1184                task.detach_and_log_err(cx);
1185            }
1186        })
1187    }
1188
1189    pub fn add_global_action<A, F>(&mut self, mut handler: F)
1190    where
1191        A: Action,
1192        F: 'static + FnMut(&A, &mut MutableAppContext),
1193    {
1194        let handler = Box::new(move |action: &dyn Action, cx: &mut MutableAppContext| {
1195            let action = action.as_any().downcast_ref().unwrap();
1196            handler(action, cx);
1197        });
1198
1199        self.action_deserializers
1200            .entry(A::qualified_name())
1201            .or_insert((TypeId::of::<A>(), A::from_json_str));
1202
1203        if self
1204            .global_actions
1205            .insert(TypeId::of::<A>(), handler)
1206            .is_some()
1207        {
1208            panic!(
1209                "registered multiple global handlers for {}",
1210                type_name::<A>()
1211            );
1212        }
1213    }
1214
1215    pub fn window_ids(&self) -> impl Iterator<Item = usize> + '_ {
1216        self.cx.windows.keys().cloned()
1217    }
1218
1219    pub fn activate_window(&self, window_id: usize) {
1220        if let Some((_, window)) = self.presenters_and_platform_windows.get(&window_id) {
1221            window.activate()
1222        }
1223    }
1224
1225    pub fn root_view<T: View>(&self, window_id: usize) -> Option<ViewHandle<T>> {
1226        self.cx
1227            .windows
1228            .get(&window_id)
1229            .and_then(|window| window.root_view.clone().downcast::<T>())
1230    }
1231
1232    pub fn window_is_active(&self, window_id: usize) -> bool {
1233        self.cx
1234            .windows
1235            .get(&window_id)
1236            .map_or(false, |window| window.is_active)
1237    }
1238
1239    pub fn window_is_fullscreen(&self, window_id: usize) -> bool {
1240        self.cx
1241            .windows
1242            .get(&window_id)
1243            .map_or(false, |window| window.is_fullscreen)
1244    }
1245
1246    pub fn render_view(&mut self, params: RenderParams) -> Result<ElementBox> {
1247        let window_id = params.window_id;
1248        let view_id = params.view_id;
1249        let mut view = self
1250            .cx
1251            .views
1252            .remove(&(window_id, view_id))
1253            .ok_or_else(|| anyhow!("view not found"))?;
1254        let element = view.render(params, self);
1255        self.cx.views.insert((window_id, view_id), view);
1256        Ok(element)
1257    }
1258
1259    pub fn render_views(
1260        &mut self,
1261        window_id: usize,
1262        titlebar_height: f32,
1263    ) -> HashMap<usize, ElementBox> {
1264        self.start_frame();
1265        #[allow(clippy::needless_collect)]
1266        let view_ids = self
1267            .views
1268            .keys()
1269            .filter_map(|(win_id, view_id)| {
1270                if *win_id == window_id {
1271                    Some(*view_id)
1272                } else {
1273                    None
1274                }
1275            })
1276            .collect::<Vec<_>>();
1277
1278        view_ids
1279            .into_iter()
1280            .map(|view_id| {
1281                (
1282                    view_id,
1283                    self.render_view(RenderParams {
1284                        window_id,
1285                        view_id,
1286                        titlebar_height,
1287                        hovered_region_ids: Default::default(),
1288                        clicked_region_ids: None,
1289                        refreshing: false,
1290                    })
1291                    .unwrap(),
1292                )
1293            })
1294            .collect()
1295    }
1296
1297    pub(crate) fn start_frame(&mut self) {
1298        self.frame_count += 1;
1299    }
1300
1301    pub fn update<T, F: FnOnce(&mut Self) -> T>(&mut self, callback: F) -> T {
1302        self.pending_flushes += 1;
1303        let result = callback(self);
1304        self.flush_effects();
1305        result
1306    }
1307
1308    pub fn set_menus(&mut self, menus: Vec<Menu>) {
1309        self.foreground_platform
1310            .set_menus(menus, &self.keystroke_matcher);
1311    }
1312
1313    fn show_character_palette(&self, window_id: usize) {
1314        let (_, window) = &self.presenters_and_platform_windows[&window_id];
1315        window.show_character_palette();
1316    }
1317
1318    pub fn minimize_window(&self, window_id: usize) {
1319        let (_, window) = &self.presenters_and_platform_windows[&window_id];
1320        window.minimize();
1321    }
1322
1323    pub fn zoom_window(&self, window_id: usize) {
1324        let (_, window) = &self.presenters_and_platform_windows[&window_id];
1325        window.zoom();
1326    }
1327
1328    pub fn toggle_window_full_screen(&self, window_id: usize) {
1329        let (_, window) = &self.presenters_and_platform_windows[&window_id];
1330        window.toggle_full_screen();
1331    }
1332
1333    fn prompt(
1334        &self,
1335        window_id: usize,
1336        level: PromptLevel,
1337        msg: &str,
1338        answers: &[&str],
1339    ) -> oneshot::Receiver<usize> {
1340        let (_, window) = &self.presenters_and_platform_windows[&window_id];
1341        window.prompt(level, msg, answers)
1342    }
1343
1344    pub fn prompt_for_paths(
1345        &self,
1346        options: PathPromptOptions,
1347    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
1348        self.foreground_platform.prompt_for_paths(options)
1349    }
1350
1351    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
1352        self.foreground_platform.prompt_for_new_path(directory)
1353    }
1354
1355    pub fn emit_global<E: Any>(&mut self, payload: E) {
1356        self.pending_effects.push_back(Effect::GlobalEvent {
1357            payload: Box::new(payload),
1358        });
1359    }
1360
1361    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
1362    where
1363        E: Entity,
1364        E::Event: 'static,
1365        H: Handle<E>,
1366        F: 'static + FnMut(H, &E::Event, &mut Self),
1367    {
1368        self.subscribe_internal(handle, move |handle, event, cx| {
1369            callback(handle, event, cx);
1370            true
1371        })
1372    }
1373
1374    pub fn subscribe_global<E, F>(&mut self, mut callback: F) -> Subscription
1375    where
1376        E: Any,
1377        F: 'static + FnMut(&E, &mut Self),
1378    {
1379        let subscription_id = post_inc(&mut self.next_subscription_id);
1380        let type_id = TypeId::of::<E>();
1381        self.pending_effects.push_back(Effect::GlobalSubscription {
1382            type_id,
1383            subscription_id,
1384            callback: Box::new(move |payload, cx| {
1385                let payload = payload.downcast_ref().expect("downcast is type safe");
1386                callback(payload, cx)
1387            }),
1388        });
1389
1390        Subscription::GlobalSubscription {
1391            id: subscription_id,
1392            type_id,
1393            subscriptions: Some(self.global_subscriptions.downgrade()),
1394        }
1395    }
1396
1397    pub fn observe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
1398    where
1399        E: Entity,
1400        E::Event: 'static,
1401        H: Handle<E>,
1402        F: 'static + FnMut(H, &mut Self),
1403    {
1404        self.observe_internal(handle, move |handle, cx| {
1405            callback(handle, cx);
1406            true
1407        })
1408    }
1409
1410    pub fn subscribe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
1411    where
1412        E: Entity,
1413        E::Event: 'static,
1414        H: Handle<E>,
1415        F: 'static + FnMut(H, &E::Event, &mut Self) -> bool,
1416    {
1417        let subscription_id = post_inc(&mut self.next_subscription_id);
1418        let emitter = handle.downgrade();
1419        self.pending_effects.push_back(Effect::Subscription {
1420            entity_id: handle.id(),
1421            subscription_id,
1422            callback: Box::new(move |payload, cx| {
1423                if let Some(emitter) = H::upgrade_from(&emitter, cx.as_ref()) {
1424                    let payload = payload.downcast_ref().expect("downcast is type safe");
1425                    callback(emitter, payload, cx)
1426                } else {
1427                    false
1428                }
1429            }),
1430        });
1431        Subscription::Subscription {
1432            id: subscription_id,
1433            entity_id: handle.id(),
1434            subscriptions: Some(self.subscriptions.downgrade()),
1435        }
1436    }
1437
1438    fn observe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
1439    where
1440        E: Entity,
1441        E::Event: 'static,
1442        H: Handle<E>,
1443        F: 'static + FnMut(H, &mut Self) -> bool,
1444    {
1445        let subscription_id = post_inc(&mut self.next_subscription_id);
1446        let observed = handle.downgrade();
1447        let entity_id = handle.id();
1448        self.pending_effects.push_back(Effect::Observation {
1449            entity_id,
1450            subscription_id,
1451            callback: Box::new(move |cx| {
1452                if let Some(observed) = H::upgrade_from(&observed, cx) {
1453                    callback(observed, cx)
1454                } else {
1455                    false
1456                }
1457            }),
1458        });
1459        Subscription::Observation {
1460            id: subscription_id,
1461            entity_id,
1462            observations: Some(self.observations.downgrade()),
1463        }
1464    }
1465
1466    fn observe_focus<F, V>(&mut self, handle: &ViewHandle<V>, mut callback: F) -> Subscription
1467    where
1468        F: 'static + FnMut(ViewHandle<V>, bool, &mut MutableAppContext) -> bool,
1469        V: View,
1470    {
1471        let subscription_id = post_inc(&mut self.next_subscription_id);
1472        let observed = handle.downgrade();
1473        let view_id = handle.id();
1474
1475        self.pending_effects.push_back(Effect::FocusObservation {
1476            view_id,
1477            subscription_id,
1478            callback: Box::new(move |focused, cx| {
1479                if let Some(observed) = observed.upgrade(cx) {
1480                    callback(observed, focused, cx)
1481                } else {
1482                    false
1483                }
1484            }),
1485        });
1486
1487        Subscription::FocusObservation {
1488            id: subscription_id,
1489            view_id,
1490            observations: Some(self.focus_observations.downgrade()),
1491        }
1492    }
1493
1494    pub fn observe_global<G, F>(&mut self, mut observe: F) -> Subscription
1495    where
1496        G: Any,
1497        F: 'static + FnMut(&mut MutableAppContext),
1498    {
1499        let type_id = TypeId::of::<G>();
1500        let id = post_inc(&mut self.next_subscription_id);
1501
1502        self.global_observations.add_callback(
1503            type_id,
1504            id,
1505            Box::new(move |cx: &mut MutableAppContext| observe(cx)),
1506        );
1507
1508        Subscription::GlobalObservation {
1509            id,
1510            type_id,
1511            observations: Some(self.global_observations.downgrade()),
1512        }
1513    }
1514
1515    pub fn observe_release<E, H, F>(&mut self, handle: &H, callback: F) -> Subscription
1516    where
1517        E: Entity,
1518        E::Event: 'static,
1519        H: Handle<E>,
1520        F: 'static + FnOnce(&E, &mut Self),
1521    {
1522        let id = post_inc(&mut self.next_subscription_id);
1523        self.release_observations
1524            .lock()
1525            .entry(handle.id())
1526            .or_default()
1527            .insert(
1528                id,
1529                Box::new(move |released, cx| {
1530                    let released = released.downcast_ref().unwrap();
1531                    callback(released, cx)
1532                }),
1533            );
1534        Subscription::ReleaseObservation {
1535            id,
1536            entity_id: handle.id(),
1537            observations: Some(Arc::downgrade(&self.release_observations)),
1538        }
1539    }
1540
1541    pub fn observe_actions<F>(&mut self, callback: F) -> Subscription
1542    where
1543        F: 'static + FnMut(TypeId, &mut MutableAppContext),
1544    {
1545        let id = post_inc(&mut self.next_subscription_id);
1546        self.action_dispatch_observations
1547            .lock()
1548            .insert(id, Box::new(callback));
1549        Subscription::ActionObservation {
1550            id,
1551            observations: Some(Arc::downgrade(&self.action_dispatch_observations)),
1552        }
1553    }
1554
1555    fn observe_window_activation<F>(&mut self, window_id: usize, callback: F) -> Subscription
1556    where
1557        F: 'static + FnMut(bool, &mut MutableAppContext) -> bool,
1558    {
1559        let subscription_id = post_inc(&mut self.next_subscription_id);
1560        self.pending_effects
1561            .push_back(Effect::WindowActivationObservation {
1562                window_id,
1563                subscription_id,
1564                callback: Box::new(callback),
1565            });
1566        Subscription::WindowActivationObservation {
1567            id: subscription_id,
1568            window_id,
1569            observations: Some(self.window_activation_observations.downgrade()),
1570        }
1571    }
1572
1573    fn observe_fullscreen<F>(&mut self, window_id: usize, callback: F) -> Subscription
1574    where
1575        F: 'static + FnMut(bool, &mut MutableAppContext) -> bool,
1576    {
1577        let subscription_id = post_inc(&mut self.next_subscription_id);
1578        self.pending_effects
1579            .push_back(Effect::WindowFullscreenObservation {
1580                window_id,
1581                subscription_id,
1582                callback: Box::new(callback),
1583            });
1584        Subscription::WindowFullscreenObservation {
1585            id: subscription_id,
1586            window_id,
1587            observations: Some(self.window_activation_observations.downgrade()),
1588        }
1589    }
1590
1591    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut MutableAppContext)) {
1592        self.pending_effects.push_back(Effect::Deferred {
1593            callback: Box::new(callback),
1594            after_window_update: false,
1595        })
1596    }
1597
1598    pub fn after_window_update(&mut self, callback: impl 'static + FnOnce(&mut MutableAppContext)) {
1599        self.pending_effects.push_back(Effect::Deferred {
1600            callback: Box::new(callback),
1601            after_window_update: true,
1602        })
1603    }
1604
1605    pub(crate) fn notify_model(&mut self, model_id: usize) {
1606        if self.pending_notifications.insert(model_id) {
1607            self.pending_effects
1608                .push_back(Effect::ModelNotification { model_id });
1609        }
1610    }
1611
1612    pub(crate) fn notify_view(&mut self, window_id: usize, view_id: usize) {
1613        if self.pending_notifications.insert(view_id) {
1614            self.pending_effects
1615                .push_back(Effect::ViewNotification { window_id, view_id });
1616        }
1617    }
1618
1619    pub(crate) fn notify_global(&mut self, type_id: TypeId) {
1620        if self.pending_global_notifications.insert(type_id) {
1621            self.pending_effects
1622                .push_back(Effect::GlobalNotification { type_id });
1623        }
1624    }
1625
1626    pub(crate) fn name_for_view(&self, window_id: usize, view_id: usize) -> Option<&str> {
1627        self.views
1628            .get(&(window_id, view_id))
1629            .map(|view| view.ui_name())
1630    }
1631
1632    pub fn all_action_names<'a>(&'a self) -> impl Iterator<Item = &'static str> + 'a {
1633        self.action_deserializers.keys().copied()
1634    }
1635
1636    pub fn available_actions(
1637        &self,
1638        window_id: usize,
1639        view_id: usize,
1640    ) -> impl Iterator<Item = (&'static str, Box<dyn Action>, SmallVec<[&Binding; 1]>)> {
1641        let mut action_types: HashSet<_> = self.global_actions.keys().copied().collect();
1642
1643        for view_id in self.parents(window_id, view_id) {
1644            if let Some(view) = self.views.get(&(window_id, view_id)) {
1645                let view_type = view.as_any().type_id();
1646                if let Some(actions) = self.actions.get(&view_type) {
1647                    action_types.extend(actions.keys().copied());
1648                }
1649            }
1650        }
1651
1652        self.action_deserializers
1653            .iter()
1654            .filter_map(move |(name, (type_id, deserialize))| {
1655                if action_types.contains(type_id) {
1656                    Some((
1657                        *name,
1658                        deserialize("{}").ok()?,
1659                        self.keystroke_matcher
1660                            .bindings_for_action_type(*type_id)
1661                            .collect(),
1662                    ))
1663                } else {
1664                    None
1665                }
1666            })
1667    }
1668
1669    pub fn is_action_available(&self, action: &dyn Action) -> bool {
1670        let action_type = action.as_any().type_id();
1671        if let Some(window_id) = self.cx.platform.key_window_id() {
1672            if let Some(focused_view_id) = self.focused_view_id(window_id) {
1673                for view_id in self.parents(window_id, focused_view_id) {
1674                    if let Some(view) = self.views.get(&(window_id, view_id)) {
1675                        let view_type = view.as_any().type_id();
1676                        if let Some(actions) = self.actions.get(&view_type) {
1677                            if actions.contains_key(&action_type) {
1678                                return true;
1679                            }
1680                        }
1681                    }
1682                }
1683            }
1684        }
1685        self.global_actions.contains_key(&action_type)
1686    }
1687
1688    /// Return keystrokes that would dispatch the given action closest to the focused view, if there are any.
1689    pub(crate) fn keystrokes_for_action(
1690        &self,
1691        window_id: usize,
1692        dispatch_path: &[usize],
1693        action: &dyn Action,
1694    ) -> Option<SmallVec<[Keystroke; 2]>> {
1695        for view_id in dispatch_path.iter().rev() {
1696            let view = self
1697                .cx
1698                .views
1699                .get(&(window_id, *view_id))
1700                .expect("view in responder chain does not exist");
1701            let cx = view.keymap_context(self.as_ref());
1702            let keystrokes = self.keystroke_matcher.keystrokes_for_action(action, &cx);
1703            if keystrokes.is_some() {
1704                return keystrokes;
1705            }
1706        }
1707
1708        None
1709    }
1710
1711    // Traverses the parent tree. Walks down the tree toward the passed
1712    // view calling visit with true. Then walks back up the tree calling visit with false.
1713    // If `visit` returns false this function will immediately return.
1714    // Returns a bool indicating if the traversal was completed early.
1715    fn visit_dispatch_path(
1716        &mut self,
1717        window_id: usize,
1718        view_id: usize,
1719        mut visit: impl FnMut(usize, bool, &mut MutableAppContext) -> bool,
1720    ) -> bool {
1721        // List of view ids from the leaf to the root of the window
1722        let path = self.parents(window_id, view_id).collect::<Vec<_>>();
1723
1724        // Walk down from the root to the leaf calling visit with capture_phase = true
1725        for view_id in path.iter().rev() {
1726            if !visit(*view_id, true, self) {
1727                return false;
1728            }
1729        }
1730
1731        // Walk up from the leaf to the root calling visit with capture_phase = false
1732        for view_id in path.iter() {
1733            if !visit(*view_id, false, self) {
1734                return false;
1735            }
1736        }
1737
1738        true
1739    }
1740
1741    // Returns an iterator over all of the view ids from the passed view up to the root of the window
1742    // Includes the passed view itself
1743    fn parents(&self, window_id: usize, mut view_id: usize) -> impl Iterator<Item = usize> + '_ {
1744        std::iter::once(view_id)
1745            .into_iter()
1746            .chain(std::iter::from_fn(move || {
1747                if let Some(ParentId::View(parent_id)) = self.parents.get(&(window_id, view_id)) {
1748                    view_id = *parent_id;
1749                    Some(view_id)
1750                } else {
1751                    None
1752                }
1753            }))
1754    }
1755
1756    fn actions_mut(
1757        &mut self,
1758        capture_phase: bool,
1759    ) -> &mut HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>> {
1760        if capture_phase {
1761            &mut self.capture_actions
1762        } else {
1763            &mut self.actions
1764        }
1765    }
1766
1767    pub fn dispatch_global_action<A: Action>(&mut self, action: A) {
1768        self.dispatch_global_action_any(&action);
1769    }
1770
1771    fn dispatch_global_action_any(&mut self, action: &dyn Action) -> bool {
1772        self.update(|this| {
1773            if let Some((name, mut handler)) = this.global_actions.remove_entry(&action.id()) {
1774                handler(action, this);
1775                this.global_actions.insert(name, handler);
1776                true
1777            } else {
1778                false
1779            }
1780        })
1781    }
1782
1783    pub fn add_bindings<T: IntoIterator<Item = keymap::Binding>>(&mut self, bindings: T) {
1784        self.keystroke_matcher.add_bindings(bindings);
1785    }
1786
1787    pub fn clear_bindings(&mut self) {
1788        self.keystroke_matcher.clear_bindings();
1789    }
1790
1791    pub fn dispatch_keystroke(&mut self, window_id: usize, keystroke: &Keystroke) -> bool {
1792        let mut pending = false;
1793
1794        if let Some(focused_view_id) = self.focused_view_id(window_id) {
1795            for view_id in self.parents(window_id, focused_view_id).collect::<Vec<_>>() {
1796                let keymap_context = self
1797                    .cx
1798                    .views
1799                    .get(&(window_id, view_id))
1800                    .unwrap()
1801                    .keymap_context(self.as_ref());
1802
1803                match self.keystroke_matcher.push_keystroke(
1804                    keystroke.clone(),
1805                    view_id,
1806                    &keymap_context,
1807                ) {
1808                    MatchResult::None => {}
1809                    MatchResult::Pending => pending = true,
1810                    MatchResult::Action(action) => {
1811                        if self.handle_dispatch_action_from_effect(
1812                            window_id,
1813                            Some(view_id),
1814                            action.as_ref(),
1815                        ) {
1816                            self.keystroke_matcher.clear_pending();
1817                            return true;
1818                        }
1819                    }
1820                }
1821            }
1822        }
1823
1824        pending
1825    }
1826
1827    pub fn default_global<T: 'static + Default>(&mut self) -> &T {
1828        let type_id = TypeId::of::<T>();
1829        self.update(|this| {
1830            if let Entry::Vacant(entry) = this.cx.globals.entry(type_id) {
1831                entry.insert(Box::new(T::default()));
1832                this.notify_global(type_id);
1833            }
1834        });
1835        self.globals.get(&type_id).unwrap().downcast_ref().unwrap()
1836    }
1837
1838    pub fn set_global<T: 'static>(&mut self, state: T) {
1839        self.update(|this| {
1840            let type_id = TypeId::of::<T>();
1841            this.cx.globals.insert(type_id, Box::new(state));
1842            this.notify_global(type_id);
1843        });
1844    }
1845
1846    pub fn update_default_global<T, F, U>(&mut self, update: F) -> U
1847    where
1848        T: 'static + Default,
1849        F: FnOnce(&mut T, &mut MutableAppContext) -> U,
1850    {
1851        self.update(|this| {
1852            let type_id = TypeId::of::<T>();
1853            let mut state = this
1854                .cx
1855                .globals
1856                .remove(&type_id)
1857                .unwrap_or_else(|| Box::new(T::default()));
1858            let result = update(state.downcast_mut().unwrap(), this);
1859            this.cx.globals.insert(type_id, state);
1860            this.notify_global(type_id);
1861            result
1862        })
1863    }
1864
1865    pub fn update_global<T, F, U>(&mut self, update: F) -> U
1866    where
1867        T: 'static,
1868        F: FnOnce(&mut T, &mut MutableAppContext) -> U,
1869    {
1870        self.update(|this| {
1871            let type_id = TypeId::of::<T>();
1872            if let Some(mut state) = this.cx.globals.remove(&type_id) {
1873                let result = update(state.downcast_mut().unwrap(), this);
1874                this.cx.globals.insert(type_id, state);
1875                this.notify_global(type_id);
1876                result
1877            } else {
1878                panic!("No global added for {}", std::any::type_name::<T>());
1879            }
1880        })
1881    }
1882
1883    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
1884    where
1885        T: Entity,
1886        F: FnOnce(&mut ModelContext<T>) -> T,
1887    {
1888        self.update(|this| {
1889            let model_id = post_inc(&mut this.next_entity_id);
1890            let handle = ModelHandle::new(model_id, &this.cx.ref_counts);
1891            let mut cx = ModelContext::new(this, model_id);
1892            let model = build_model(&mut cx);
1893            this.cx.models.insert(model_id, Box::new(model));
1894            handle
1895        })
1896    }
1897
1898    pub fn add_window<T, F>(
1899        &mut self,
1900        window_options: WindowOptions,
1901        build_root_view: F,
1902    ) -> (usize, ViewHandle<T>)
1903    where
1904        T: View,
1905        F: FnOnce(&mut ViewContext<T>) -> T,
1906    {
1907        self.update(|this| {
1908            let window_id = post_inc(&mut this.next_window_id);
1909            let root_view = this
1910                .build_and_insert_view(window_id, ParentId::Root, |cx| Some(build_root_view(cx)))
1911                .unwrap();
1912            this.cx.windows.insert(
1913                window_id,
1914                Window {
1915                    root_view: root_view.clone().into(),
1916                    focused_view_id: Some(root_view.id()),
1917                    is_active: false,
1918                    invalidation: None,
1919                    is_fullscreen: false,
1920                },
1921            );
1922            root_view.update(this, |view, cx| view.on_focus_in(cx.handle().into(), cx));
1923            this.open_platform_window(window_id, window_options);
1924
1925            (window_id, root_view)
1926        })
1927    }
1928
1929    // pub fn add_status_bar_item<I, F>(&mut self, build_item: F)
1930    // where
1931    //     I: View,
1932    //     F: FnOnce(&mut ViewContext<I>) -> I,
1933    // {
1934    //     mem::forget(self.platform.add_status_item());
1935    // }
1936
1937    pub fn replace_root_view<T, F>(&mut self, window_id: usize, build_root_view: F) -> ViewHandle<T>
1938    where
1939        T: View,
1940        F: FnOnce(&mut ViewContext<T>) -> T,
1941    {
1942        self.update(|this| {
1943            let root_view = this
1944                .build_and_insert_view(window_id, ParentId::Root, |cx| Some(build_root_view(cx)))
1945                .unwrap();
1946            let window = this.cx.windows.get_mut(&window_id).unwrap();
1947            window.root_view = root_view.clone().into();
1948            window.focused_view_id = Some(root_view.id());
1949            root_view
1950        })
1951    }
1952
1953    pub fn remove_window(&mut self, window_id: usize) {
1954        self.cx.windows.remove(&window_id);
1955        self.presenters_and_platform_windows.remove(&window_id);
1956        self.flush_effects();
1957    }
1958
1959    fn open_platform_window(&mut self, window_id: usize, window_options: WindowOptions) {
1960        let mut window =
1961            self.cx
1962                .platform
1963                .open_window(window_id, window_options, self.foreground.clone());
1964        let presenter = Rc::new(RefCell::new(
1965            self.build_presenter(window_id, window.titlebar_height()),
1966        ));
1967
1968        {
1969            let mut app = self.upgrade();
1970            let presenter = Rc::downgrade(&presenter);
1971            window.on_event(Box::new(move |event| {
1972                app.update(|cx| {
1973                    if let Some(presenter) = presenter.upgrade() {
1974                        if let Event::KeyDown(KeyDownEvent { keystroke, .. }) = &event {
1975                            if cx.dispatch_keystroke(window_id, keystroke) {
1976                                return true;
1977                            }
1978                        }
1979
1980                        presenter.borrow_mut().dispatch_event(event, false, cx)
1981                    } else {
1982                        false
1983                    }
1984                })
1985            }));
1986        }
1987
1988        {
1989            let mut app = self.upgrade();
1990            window.on_active_status_change(Box::new(move |is_active| {
1991                app.update(|cx| cx.window_changed_active_status(window_id, is_active))
1992            }));
1993        }
1994
1995        {
1996            let mut app = self.upgrade();
1997            window.on_resize(Box::new(move || {
1998                app.update(|cx| cx.window_was_resized(window_id))
1999            }));
2000        }
2001
2002        {
2003            let mut app = self.upgrade();
2004            window.on_fullscreen(Box::new(move |is_fullscreen| {
2005                app.update(|cx| cx.window_was_fullscreen_changed(window_id, is_fullscreen))
2006            }));
2007        }
2008
2009        {
2010            let mut app = self.upgrade();
2011            window.on_close(Box::new(move || {
2012                app.update(|cx| cx.remove_window(window_id));
2013            }));
2014        }
2015
2016        window.set_input_handler(Box::new(WindowInputHandler {
2017            app: self.upgrade().0,
2018            window_id,
2019        }));
2020
2021        let scene =
2022            presenter
2023                .borrow_mut()
2024                .build_scene(window.size(), window.scale_factor(), false, self);
2025        window.present_scene(scene);
2026        self.presenters_and_platform_windows
2027            .insert(window_id, (presenter.clone(), window));
2028    }
2029
2030    pub fn build_presenter(&mut self, window_id: usize, titlebar_height: f32) -> Presenter {
2031        Presenter::new(
2032            window_id,
2033            titlebar_height,
2034            self.cx.font_cache.clone(),
2035            TextLayoutCache::new(self.cx.platform.fonts()),
2036            self.assets.clone(),
2037            self,
2038        )
2039    }
2040
2041    pub fn add_view<T, F>(
2042        &mut self,
2043        parent_handle: impl Into<AnyViewHandle>,
2044        build_view: F,
2045    ) -> ViewHandle<T>
2046    where
2047        T: View,
2048        F: FnOnce(&mut ViewContext<T>) -> T,
2049    {
2050        let parent_handle = parent_handle.into();
2051        self.build_and_insert_view(
2052            parent_handle.window_id,
2053            ParentId::View(parent_handle.view_id),
2054            |cx| Some(build_view(cx)),
2055        )
2056        .unwrap()
2057    }
2058
2059    pub fn add_option_view<T, F>(
2060        &mut self,
2061        parent_handle: impl Into<AnyViewHandle>,
2062        build_view: F,
2063    ) -> Option<ViewHandle<T>>
2064    where
2065        T: View,
2066        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
2067    {
2068        let parent_handle = parent_handle.into();
2069        self.build_and_insert_view(
2070            parent_handle.window_id,
2071            ParentId::View(parent_handle.view_id),
2072            build_view,
2073        )
2074    }
2075
2076    pub(crate) fn build_and_insert_view<T, F>(
2077        &mut self,
2078        window_id: usize,
2079        parent_id: ParentId,
2080        build_view: F,
2081    ) -> Option<ViewHandle<T>>
2082    where
2083        T: View,
2084        F: FnOnce(&mut ViewContext<T>) -> Option<T>,
2085    {
2086        self.update(|this| {
2087            let view_id = post_inc(&mut this.next_entity_id);
2088            let mut cx = ViewContext::new(this, window_id, view_id);
2089            let handle = if let Some(view) = build_view(&mut cx) {
2090                this.cx.views.insert((window_id, view_id), Box::new(view));
2091                this.cx.parents.insert((window_id, view_id), parent_id);
2092                if let Some(window) = this.cx.windows.get_mut(&window_id) {
2093                    window
2094                        .invalidation
2095                        .get_or_insert_with(Default::default)
2096                        .updated
2097                        .insert(view_id);
2098                }
2099                Some(ViewHandle::new(window_id, view_id, &this.cx.ref_counts))
2100            } else {
2101                None
2102            };
2103            handle
2104        })
2105    }
2106
2107    fn remove_dropped_entities(&mut self) {
2108        loop {
2109            let (dropped_models, dropped_views, dropped_element_states) =
2110                self.cx.ref_counts.lock().take_dropped();
2111            if dropped_models.is_empty()
2112                && dropped_views.is_empty()
2113                && dropped_element_states.is_empty()
2114            {
2115                break;
2116            }
2117
2118            for model_id in dropped_models {
2119                self.subscriptions.remove(model_id);
2120                self.observations.remove(model_id);
2121                let mut model = self.cx.models.remove(&model_id).unwrap();
2122                model.release(self);
2123                self.pending_effects
2124                    .push_back(Effect::ModelRelease { model_id, model });
2125            }
2126
2127            for (window_id, view_id) in dropped_views {
2128                self.subscriptions.remove(view_id);
2129                self.observations.remove(view_id);
2130                let mut view = self.cx.views.remove(&(window_id, view_id)).unwrap();
2131                view.release(self);
2132                let change_focus_to = self.cx.windows.get_mut(&window_id).and_then(|window| {
2133                    window
2134                        .invalidation
2135                        .get_or_insert_with(Default::default)
2136                        .removed
2137                        .push(view_id);
2138                    if window.focused_view_id == Some(view_id) {
2139                        Some(window.root_view.id())
2140                    } else {
2141                        None
2142                    }
2143                });
2144                self.cx.parents.remove(&(window_id, view_id));
2145
2146                if let Some(view_id) = change_focus_to {
2147                    self.handle_focus_effect(window_id, Some(view_id));
2148                }
2149
2150                self.pending_effects
2151                    .push_back(Effect::ViewRelease { view_id, view });
2152            }
2153
2154            for key in dropped_element_states {
2155                self.cx.element_states.remove(&key);
2156            }
2157        }
2158    }
2159
2160    fn flush_effects(&mut self) {
2161        self.pending_flushes = self.pending_flushes.saturating_sub(1);
2162        let mut after_window_update_callbacks = Vec::new();
2163
2164        if !self.flushing_effects && self.pending_flushes == 0 {
2165            self.flushing_effects = true;
2166
2167            let mut refreshing = false;
2168            loop {
2169                if let Some(effect) = self.pending_effects.pop_front() {
2170                    if let Some(pending_focus_index) = self.pending_focus_index.as_mut() {
2171                        *pending_focus_index = pending_focus_index.saturating_sub(1);
2172                    }
2173                    match effect {
2174                        Effect::Subscription {
2175                            entity_id,
2176                            subscription_id,
2177                            callback,
2178                        } => self.subscriptions.add_or_remove_callback(
2179                            entity_id,
2180                            subscription_id,
2181                            callback,
2182                        ),
2183
2184                        Effect::Event { entity_id, payload } => {
2185                            let mut subscriptions = self.subscriptions.clone();
2186                            subscriptions.emit_and_cleanup(entity_id, self, |callback, this| {
2187                                callback(payload.as_ref(), this)
2188                            })
2189                        }
2190
2191                        Effect::GlobalSubscription {
2192                            type_id,
2193                            subscription_id,
2194                            callback,
2195                        } => self.global_subscriptions.add_or_remove_callback(
2196                            type_id,
2197                            subscription_id,
2198                            callback,
2199                        ),
2200
2201                        Effect::GlobalEvent { payload } => self.emit_global_event(payload),
2202
2203                        Effect::Observation {
2204                            entity_id,
2205                            subscription_id,
2206                            callback,
2207                        } => self.observations.add_or_remove_callback(
2208                            entity_id,
2209                            subscription_id,
2210                            callback,
2211                        ),
2212
2213                        Effect::ModelNotification { model_id } => {
2214                            let mut observations = self.observations.clone();
2215                            observations
2216                                .emit_and_cleanup(model_id, self, |callback, this| callback(this));
2217                        }
2218
2219                        Effect::ViewNotification { window_id, view_id } => {
2220                            self.handle_view_notification_effect(window_id, view_id)
2221                        }
2222
2223                        Effect::GlobalNotification { type_id } => {
2224                            let mut subscriptions = self.global_observations.clone();
2225                            subscriptions.emit_and_cleanup(type_id, self, |callback, this| {
2226                                callback(this);
2227                                true
2228                            });
2229                        }
2230
2231                        Effect::Deferred {
2232                            callback,
2233                            after_window_update,
2234                        } => {
2235                            if after_window_update {
2236                                after_window_update_callbacks.push(callback);
2237                            } else {
2238                                callback(self)
2239                            }
2240                        }
2241
2242                        Effect::ModelRelease { model_id, model } => {
2243                            self.handle_entity_release_effect(model_id, model.as_any())
2244                        }
2245
2246                        Effect::ViewRelease { view_id, view } => {
2247                            self.handle_entity_release_effect(view_id, view.as_any())
2248                        }
2249
2250                        Effect::Focus { window_id, view_id } => {
2251                            self.handle_focus_effect(window_id, view_id);
2252                        }
2253
2254                        Effect::FocusObservation {
2255                            view_id,
2256                            subscription_id,
2257                            callback,
2258                        } => {
2259                            self.focus_observations.add_or_remove_callback(
2260                                view_id,
2261                                subscription_id,
2262                                callback,
2263                            );
2264                        }
2265
2266                        Effect::ResizeWindow { window_id } => {
2267                            if let Some(window) = self.cx.windows.get_mut(&window_id) {
2268                                window
2269                                    .invalidation
2270                                    .get_or_insert(WindowInvalidation::default());
2271                            }
2272                        }
2273
2274                        Effect::WindowActivationObservation {
2275                            window_id,
2276                            subscription_id,
2277                            callback,
2278                        } => self.window_activation_observations.add_or_remove_callback(
2279                            window_id,
2280                            subscription_id,
2281                            callback,
2282                        ),
2283
2284                        Effect::ActivateWindow {
2285                            window_id,
2286                            is_active,
2287                        } => self.handle_window_activation_effect(window_id, is_active),
2288
2289                        Effect::WindowFullscreenObservation {
2290                            window_id,
2291                            subscription_id,
2292                            callback,
2293                        } => self.window_fullscreen_observations.add_or_remove_callback(
2294                            window_id,
2295                            subscription_id,
2296                            callback,
2297                        ),
2298
2299                        Effect::FullscreenWindow {
2300                            window_id,
2301                            is_fullscreen,
2302                        } => self.handle_fullscreen_effect(window_id, is_fullscreen),
2303
2304                        Effect::RefreshWindows => {
2305                            refreshing = true;
2306                        }
2307                        Effect::DispatchActionFrom {
2308                            window_id,
2309                            view_id,
2310                            action,
2311                        } => {
2312                            self.handle_dispatch_action_from_effect(
2313                                window_id,
2314                                Some(view_id),
2315                                action.as_ref(),
2316                            );
2317                        }
2318                        Effect::ActionDispatchNotification { action_id } => {
2319                            self.handle_action_dispatch_notification_effect(action_id)
2320                        }
2321                        Effect::WindowShouldCloseSubscription {
2322                            window_id,
2323                            callback,
2324                        } => {
2325                            self.handle_window_should_close_subscription_effect(window_id, callback)
2326                        }
2327                    }
2328                    self.pending_notifications.clear();
2329                    self.remove_dropped_entities();
2330                } else {
2331                    self.remove_dropped_entities();
2332                    if refreshing {
2333                        self.perform_window_refresh();
2334                    } else {
2335                        self.update_windows();
2336                    }
2337
2338                    if self.pending_effects.is_empty() {
2339                        for callback in after_window_update_callbacks.drain(..) {
2340                            callback(self);
2341                        }
2342
2343                        if self.pending_effects.is_empty() {
2344                            self.flushing_effects = false;
2345                            self.pending_notifications.clear();
2346                            self.pending_global_notifications.clear();
2347                            break;
2348                        }
2349                    }
2350
2351                    refreshing = false;
2352                }
2353            }
2354        }
2355    }
2356
2357    fn update_windows(&mut self) {
2358        let mut invalidations: HashMap<_, _> = Default::default();
2359        for (window_id, window) in &mut self.cx.windows {
2360            if let Some(invalidation) = window.invalidation.take() {
2361                invalidations.insert(*window_id, invalidation);
2362            }
2363        }
2364
2365        for (window_id, mut invalidation) in invalidations {
2366            if let Some((presenter, mut window)) =
2367                self.presenters_and_platform_windows.remove(&window_id)
2368            {
2369                {
2370                    let mut presenter = presenter.borrow_mut();
2371                    presenter.invalidate(&mut invalidation, self);
2372                    let scene =
2373                        presenter.build_scene(window.size(), window.scale_factor(), false, self);
2374                    window.present_scene(scene);
2375                }
2376                self.presenters_and_platform_windows
2377                    .insert(window_id, (presenter, window));
2378            }
2379        }
2380    }
2381
2382    fn window_was_resized(&mut self, window_id: usize) {
2383        self.pending_effects
2384            .push_back(Effect::ResizeWindow { window_id });
2385    }
2386
2387    fn window_was_fullscreen_changed(&mut self, window_id: usize, is_fullscreen: bool) {
2388        self.pending_effects.push_back(Effect::FullscreenWindow {
2389            window_id,
2390            is_fullscreen,
2391        });
2392    }
2393
2394    fn window_changed_active_status(&mut self, window_id: usize, is_active: bool) {
2395        self.pending_effects.push_back(Effect::ActivateWindow {
2396            window_id,
2397            is_active,
2398        });
2399    }
2400
2401    pub fn refresh_windows(&mut self) {
2402        self.pending_effects.push_back(Effect::RefreshWindows);
2403    }
2404
2405    pub fn dispatch_action_at(&mut self, window_id: usize, view_id: usize, action: impl Action) {
2406        self.dispatch_any_action_at(window_id, view_id, Box::new(action));
2407    }
2408
2409    pub fn dispatch_any_action_at(
2410        &mut self,
2411        window_id: usize,
2412        view_id: usize,
2413        action: Box<dyn Action>,
2414    ) {
2415        self.pending_effects.push_back(Effect::DispatchActionFrom {
2416            window_id,
2417            view_id,
2418            action,
2419        });
2420    }
2421
2422    fn perform_window_refresh(&mut self) {
2423        let mut presenters = mem::take(&mut self.presenters_and_platform_windows);
2424        for (window_id, (presenter, window)) in &mut presenters {
2425            let mut invalidation = self
2426                .cx
2427                .windows
2428                .get_mut(window_id)
2429                .unwrap()
2430                .invalidation
2431                .take();
2432            let mut presenter = presenter.borrow_mut();
2433            presenter.refresh(
2434                invalidation.as_mut().unwrap_or(&mut Default::default()),
2435                self,
2436            );
2437            let scene = presenter.build_scene(window.size(), window.scale_factor(), true, self);
2438            window.present_scene(scene);
2439        }
2440        self.presenters_and_platform_windows = presenters;
2441    }
2442
2443    fn emit_global_event(&mut self, payload: Box<dyn Any>) {
2444        let type_id = (&*payload).type_id();
2445
2446        let mut subscriptions = self.global_subscriptions.clone();
2447        subscriptions.emit_and_cleanup(type_id, self, |callback, this| {
2448            callback(payload.as_ref(), this);
2449            true //Always alive
2450        });
2451    }
2452
2453    fn handle_view_notification_effect(
2454        &mut self,
2455        observed_window_id: usize,
2456        observed_view_id: usize,
2457    ) {
2458        if self
2459            .cx
2460            .views
2461            .contains_key(&(observed_window_id, observed_view_id))
2462        {
2463            if let Some(window) = self.cx.windows.get_mut(&observed_window_id) {
2464                window
2465                    .invalidation
2466                    .get_or_insert_with(Default::default)
2467                    .updated
2468                    .insert(observed_view_id);
2469            }
2470
2471            let mut observations = self.observations.clone();
2472            observations.emit_and_cleanup(observed_view_id, self, |callback, this| callback(this));
2473        }
2474    }
2475
2476    fn handle_entity_release_effect(&mut self, entity_id: usize, entity: &dyn Any) {
2477        let callbacks = self.release_observations.lock().remove(&entity_id);
2478        if let Some(callbacks) = callbacks {
2479            for (_, callback) in callbacks {
2480                callback(entity, self);
2481            }
2482        }
2483    }
2484
2485    fn handle_fullscreen_effect(&mut self, window_id: usize, is_fullscreen: bool) {
2486        //Short circuit evaluation if we're already g2g
2487        if self
2488            .cx
2489            .windows
2490            .get(&window_id)
2491            .map(|w| w.is_fullscreen == is_fullscreen)
2492            .unwrap_or(false)
2493        {
2494            return;
2495        }
2496
2497        self.update(|this| {
2498            let window = this.cx.windows.get_mut(&window_id)?;
2499            window.is_fullscreen = is_fullscreen;
2500
2501            let mut observations = this.window_fullscreen_observations.clone();
2502            observations.emit_and_cleanup(window_id, this, |callback, this| {
2503                callback(is_fullscreen, this)
2504            });
2505
2506            Some(())
2507        });
2508    }
2509
2510    fn handle_window_activation_effect(&mut self, window_id: usize, active: bool) {
2511        //Short circuit evaluation if we're already g2g
2512        if self
2513            .cx
2514            .windows
2515            .get(&window_id)
2516            .map(|w| w.is_active == active)
2517            .unwrap_or(false)
2518        {
2519            return;
2520        }
2521
2522        self.update(|this| {
2523            let window = this.cx.windows.get_mut(&window_id)?;
2524            window.is_active = active;
2525
2526            //Handle focus
2527            let focused_id = window.focused_view_id?;
2528            for view_id in this.parents(window_id, focused_id).collect::<Vec<_>>() {
2529                if let Some(mut view) = this.cx.views.remove(&(window_id, view_id)) {
2530                    if active {
2531                        view.on_focus_in(this, window_id, view_id, focused_id);
2532                    } else {
2533                        view.on_focus_out(this, window_id, view_id, focused_id);
2534                    }
2535                    this.cx.views.insert((window_id, view_id), view);
2536                }
2537            }
2538
2539            let mut observations = this.window_activation_observations.clone();
2540            observations.emit_and_cleanup(window_id, this, |callback, this| callback(active, this));
2541
2542            Some(())
2543        });
2544    }
2545
2546    fn handle_focus_effect(&mut self, window_id: usize, focused_id: Option<usize>) {
2547        self.pending_focus_index.take();
2548
2549        if self
2550            .cx
2551            .windows
2552            .get(&window_id)
2553            .map(|w| w.focused_view_id)
2554            .map_or(false, |cur_focused| cur_focused == focused_id)
2555        {
2556            return;
2557        }
2558
2559        self.update(|this| {
2560            let blurred_id = this.cx.windows.get_mut(&window_id).and_then(|window| {
2561                let blurred_id = window.focused_view_id;
2562                window.focused_view_id = focused_id;
2563                blurred_id
2564            });
2565
2566            let blurred_parents = blurred_id
2567                .map(|blurred_id| this.parents(window_id, blurred_id).collect::<Vec<_>>())
2568                .unwrap_or_default();
2569            let focused_parents = focused_id
2570                .map(|focused_id| this.parents(window_id, focused_id).collect::<Vec<_>>())
2571                .unwrap_or_default();
2572
2573            if let Some(blurred_id) = blurred_id {
2574                for view_id in blurred_parents.iter().copied() {
2575                    if let Some(mut view) = this.cx.views.remove(&(window_id, view_id)) {
2576                        view.on_focus_out(this, window_id, view_id, blurred_id);
2577                        this.cx.views.insert((window_id, view_id), view);
2578                    }
2579                }
2580
2581                let mut subscriptions = this.focus_observations.clone();
2582                subscriptions
2583                    .emit_and_cleanup(blurred_id, this, |callback, this| callback(false, this));
2584            }
2585
2586            if let Some(focused_id) = focused_id {
2587                for view_id in focused_parents {
2588                    if let Some(mut view) = this.cx.views.remove(&(window_id, view_id)) {
2589                        view.on_focus_in(this, window_id, view_id, focused_id);
2590                        this.cx.views.insert((window_id, view_id), view);
2591                    }
2592                }
2593
2594                let mut subscriptions = this.focus_observations.clone();
2595                subscriptions
2596                    .emit_and_cleanup(focused_id, this, |callback, this| callback(true, this));
2597            }
2598        })
2599    }
2600
2601    fn handle_dispatch_action_from_effect(
2602        &mut self,
2603        window_id: usize,
2604        view_id: Option<usize>,
2605        action: &dyn Action,
2606    ) -> bool {
2607        self.update(|this| {
2608            if let Some(view_id) = view_id {
2609                this.halt_action_dispatch = false;
2610                this.visit_dispatch_path(window_id, view_id, |view_id, capture_phase, this| {
2611                    if let Some(mut view) = this.cx.views.remove(&(window_id, view_id)) {
2612                        let type_id = view.as_any().type_id();
2613
2614                        if let Some((name, mut handlers)) = this
2615                            .actions_mut(capture_phase)
2616                            .get_mut(&type_id)
2617                            .and_then(|h| h.remove_entry(&action.id()))
2618                        {
2619                            for handler in handlers.iter_mut().rev() {
2620                                this.halt_action_dispatch = true;
2621                                handler(view.as_mut(), action, this, window_id, view_id);
2622                                if this.halt_action_dispatch {
2623                                    break;
2624                                }
2625                            }
2626                            this.actions_mut(capture_phase)
2627                                .get_mut(&type_id)
2628                                .unwrap()
2629                                .insert(name, handlers);
2630                        }
2631
2632                        this.cx.views.insert((window_id, view_id), view);
2633                    }
2634
2635                    !this.halt_action_dispatch
2636                });
2637            }
2638
2639            if !this.halt_action_dispatch {
2640                this.halt_action_dispatch = this.dispatch_global_action_any(action);
2641            }
2642
2643            this.pending_effects
2644                .push_back(Effect::ActionDispatchNotification {
2645                    action_id: action.id(),
2646                });
2647            this.halt_action_dispatch
2648        })
2649    }
2650
2651    fn handle_action_dispatch_notification_effect(&mut self, action_id: TypeId) {
2652        let mut callbacks = mem::take(&mut *self.action_dispatch_observations.lock());
2653        for callback in callbacks.values_mut() {
2654            callback(action_id, self);
2655        }
2656        self.action_dispatch_observations.lock().extend(callbacks);
2657    }
2658
2659    fn handle_window_should_close_subscription_effect(
2660        &mut self,
2661        window_id: usize,
2662        mut callback: WindowShouldCloseSubscriptionCallback,
2663    ) {
2664        let mut app = self.upgrade();
2665        if let Some((_, window)) = self.presenters_and_platform_windows.get_mut(&window_id) {
2666            window.on_should_close(Box::new(move || app.update(|cx| callback(cx))))
2667        }
2668    }
2669
2670    pub fn focus(&mut self, window_id: usize, view_id: Option<usize>) {
2671        if let Some(pending_focus_index) = self.pending_focus_index {
2672            self.pending_effects.remove(pending_focus_index);
2673        }
2674        self.pending_focus_index = Some(self.pending_effects.len());
2675        self.pending_effects
2676            .push_back(Effect::Focus { window_id, view_id });
2677    }
2678
2679    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
2680    where
2681        F: FnOnce(AsyncAppContext) -> Fut,
2682        Fut: 'static + Future<Output = T>,
2683        T: 'static,
2684    {
2685        let future = f(self.to_async());
2686        let cx = self.to_async();
2687        self.foreground.spawn(async move {
2688            let result = future.await;
2689            cx.0.borrow_mut().flush_effects();
2690            result
2691        })
2692    }
2693
2694    pub fn to_async(&self) -> AsyncAppContext {
2695        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
2696    }
2697
2698    pub fn write_to_clipboard(&self, item: ClipboardItem) {
2699        self.cx.platform.write_to_clipboard(item);
2700    }
2701
2702    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
2703        self.cx.platform.read_from_clipboard()
2704    }
2705
2706    #[cfg(any(test, feature = "test-support"))]
2707    pub fn leak_detector(&self) -> Arc<Mutex<LeakDetector>> {
2708        self.cx.ref_counts.lock().leak_detector.clone()
2709    }
2710}
2711
2712impl ReadModel for MutableAppContext {
2713    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2714        if let Some(model) = self.cx.models.get(&handle.model_id) {
2715            model
2716                .as_any()
2717                .downcast_ref()
2718                .expect("downcast is type safe")
2719        } else {
2720            panic!("circular model reference");
2721        }
2722    }
2723}
2724
2725impl UpdateModel for MutableAppContext {
2726    fn update_model<T: Entity, V>(
2727        &mut self,
2728        handle: &ModelHandle<T>,
2729        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
2730    ) -> V {
2731        if let Some(mut model) = self.cx.models.remove(&handle.model_id) {
2732            self.update(|this| {
2733                let mut cx = ModelContext::new(this, handle.model_id);
2734                let result = update(
2735                    model
2736                        .as_any_mut()
2737                        .downcast_mut()
2738                        .expect("downcast is type safe"),
2739                    &mut cx,
2740                );
2741                this.cx.models.insert(handle.model_id, model);
2742                result
2743            })
2744        } else {
2745            panic!("circular model update");
2746        }
2747    }
2748}
2749
2750impl UpgradeModelHandle for MutableAppContext {
2751    fn upgrade_model_handle<T: Entity>(
2752        &self,
2753        handle: &WeakModelHandle<T>,
2754    ) -> Option<ModelHandle<T>> {
2755        self.cx.upgrade_model_handle(handle)
2756    }
2757
2758    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
2759        self.cx.model_handle_is_upgradable(handle)
2760    }
2761
2762    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
2763        self.cx.upgrade_any_model_handle(handle)
2764    }
2765}
2766
2767impl UpgradeViewHandle for MutableAppContext {
2768    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
2769        self.cx.upgrade_view_handle(handle)
2770    }
2771
2772    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
2773        self.cx.upgrade_any_view_handle(handle)
2774    }
2775}
2776
2777impl ReadView for MutableAppContext {
2778    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2779        if let Some(view) = self.cx.views.get(&(handle.window_id, handle.view_id)) {
2780            view.as_any().downcast_ref().expect("downcast is type safe")
2781        } else {
2782            panic!("circular view reference for type {}", type_name::<T>());
2783        }
2784    }
2785}
2786
2787impl UpdateView for MutableAppContext {
2788    fn update_view<T, S>(
2789        &mut self,
2790        handle: &ViewHandle<T>,
2791        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
2792    ) -> S
2793    where
2794        T: View,
2795    {
2796        self.update(|this| {
2797            let mut view = this
2798                .cx
2799                .views
2800                .remove(&(handle.window_id, handle.view_id))
2801                .expect("circular view update");
2802
2803            let mut cx = ViewContext::new(this, handle.window_id, handle.view_id);
2804            let result = update(
2805                view.as_any_mut()
2806                    .downcast_mut()
2807                    .expect("downcast is type safe"),
2808                &mut cx,
2809            );
2810            this.cx
2811                .views
2812                .insert((handle.window_id, handle.view_id), view);
2813            result
2814        })
2815    }
2816}
2817
2818impl AsRef<AppContext> for MutableAppContext {
2819    fn as_ref(&self) -> &AppContext {
2820        &self.cx
2821    }
2822}
2823
2824impl Deref for MutableAppContext {
2825    type Target = AppContext;
2826
2827    fn deref(&self) -> &Self::Target {
2828        &self.cx
2829    }
2830}
2831
2832#[derive(Debug)]
2833pub enum ParentId {
2834    View(usize),
2835    Root,
2836}
2837
2838pub struct AppContext {
2839    models: HashMap<usize, Box<dyn AnyModel>>,
2840    views: HashMap<(usize, usize), Box<dyn AnyView>>,
2841    pub(crate) parents: HashMap<(usize, usize), ParentId>,
2842    windows: HashMap<usize, Window>,
2843    globals: HashMap<TypeId, Box<dyn Any>>,
2844    element_states: HashMap<ElementStateId, Box<dyn Any>>,
2845    background: Arc<executor::Background>,
2846    ref_counts: Arc<Mutex<RefCounts>>,
2847    font_cache: Arc<FontCache>,
2848    platform: Arc<dyn Platform>,
2849}
2850
2851impl AppContext {
2852    pub(crate) fn root_view(&self, window_id: usize) -> Option<AnyViewHandle> {
2853        self.windows
2854            .get(&window_id)
2855            .map(|window| window.root_view.clone())
2856    }
2857
2858    pub fn root_view_id(&self, window_id: usize) -> Option<usize> {
2859        self.windows
2860            .get(&window_id)
2861            .map(|window| window.root_view.id())
2862    }
2863
2864    pub fn focused_view_id(&self, window_id: usize) -> Option<usize> {
2865        self.windows
2866            .get(&window_id)
2867            .and_then(|window| window.focused_view_id)
2868    }
2869
2870    pub fn background(&self) -> &Arc<executor::Background> {
2871        &self.background
2872    }
2873
2874    pub fn font_cache(&self) -> &Arc<FontCache> {
2875        &self.font_cache
2876    }
2877
2878    pub fn platform(&self) -> &Arc<dyn Platform> {
2879        &self.platform
2880    }
2881
2882    pub fn has_global<T: 'static>(&self) -> bool {
2883        self.globals.contains_key(&TypeId::of::<T>())
2884    }
2885
2886    pub fn global<T: 'static>(&self) -> &T {
2887        if let Some(global) = self.globals.get(&TypeId::of::<T>()) {
2888            global.downcast_ref().unwrap()
2889        } else {
2890            panic!("no global has been added for {}", type_name::<T>());
2891        }
2892    }
2893}
2894
2895impl ReadModel for AppContext {
2896    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2897        if let Some(model) = self.models.get(&handle.model_id) {
2898            model
2899                .as_any()
2900                .downcast_ref()
2901                .expect("downcast should be type safe")
2902        } else {
2903            panic!("circular model reference");
2904        }
2905    }
2906}
2907
2908impl UpgradeModelHandle for AppContext {
2909    fn upgrade_model_handle<T: Entity>(
2910        &self,
2911        handle: &WeakModelHandle<T>,
2912    ) -> Option<ModelHandle<T>> {
2913        if self.models.contains_key(&handle.model_id) {
2914            Some(ModelHandle::new(handle.model_id, &self.ref_counts))
2915        } else {
2916            None
2917        }
2918    }
2919
2920    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
2921        self.models.contains_key(&handle.model_id)
2922    }
2923
2924    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
2925        if self.models.contains_key(&handle.model_id) {
2926            Some(AnyModelHandle::new(
2927                handle.model_id,
2928                handle.model_type,
2929                self.ref_counts.clone(),
2930            ))
2931        } else {
2932            None
2933        }
2934    }
2935}
2936
2937impl UpgradeViewHandle for AppContext {
2938    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
2939        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
2940            Some(ViewHandle::new(
2941                handle.window_id,
2942                handle.view_id,
2943                &self.ref_counts,
2944            ))
2945        } else {
2946            None
2947        }
2948    }
2949
2950    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
2951        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
2952            Some(AnyViewHandle::new(
2953                handle.window_id,
2954                handle.view_id,
2955                handle.view_type,
2956                self.ref_counts.clone(),
2957            ))
2958        } else {
2959            None
2960        }
2961    }
2962}
2963
2964impl ReadView for AppContext {
2965    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2966        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
2967            view.as_any()
2968                .downcast_ref()
2969                .expect("downcast should be type safe")
2970        } else {
2971            panic!("circular view reference");
2972        }
2973    }
2974}
2975
2976struct Window {
2977    root_view: AnyViewHandle,
2978    focused_view_id: Option<usize>,
2979    is_active: bool,
2980    is_fullscreen: bool,
2981    invalidation: Option<WindowInvalidation>,
2982}
2983
2984#[derive(Default, Clone)]
2985pub struct WindowInvalidation {
2986    pub updated: HashSet<usize>,
2987    pub removed: Vec<usize>,
2988}
2989
2990pub enum Effect {
2991    Subscription {
2992        entity_id: usize,
2993        subscription_id: usize,
2994        callback: SubscriptionCallback,
2995    },
2996    Event {
2997        entity_id: usize,
2998        payload: Box<dyn Any>,
2999    },
3000    GlobalSubscription {
3001        type_id: TypeId,
3002        subscription_id: usize,
3003        callback: GlobalSubscriptionCallback,
3004    },
3005    GlobalEvent {
3006        payload: Box<dyn Any>,
3007    },
3008    Observation {
3009        entity_id: usize,
3010        subscription_id: usize,
3011        callback: ObservationCallback,
3012    },
3013    ModelNotification {
3014        model_id: usize,
3015    },
3016    ViewNotification {
3017        window_id: usize,
3018        view_id: usize,
3019    },
3020    Deferred {
3021        callback: Box<dyn FnOnce(&mut MutableAppContext)>,
3022        after_window_update: bool,
3023    },
3024    GlobalNotification {
3025        type_id: TypeId,
3026    },
3027    ModelRelease {
3028        model_id: usize,
3029        model: Box<dyn AnyModel>,
3030    },
3031    ViewRelease {
3032        view_id: usize,
3033        view: Box<dyn AnyView>,
3034    },
3035    Focus {
3036        window_id: usize,
3037        view_id: Option<usize>,
3038    },
3039    FocusObservation {
3040        view_id: usize,
3041        subscription_id: usize,
3042        callback: FocusObservationCallback,
3043    },
3044    ResizeWindow {
3045        window_id: usize,
3046    },
3047    FullscreenWindow {
3048        window_id: usize,
3049        is_fullscreen: bool,
3050    },
3051    ActivateWindow {
3052        window_id: usize,
3053        is_active: bool,
3054    },
3055    WindowActivationObservation {
3056        window_id: usize,
3057        subscription_id: usize,
3058        callback: WindowActivationCallback,
3059    },
3060    WindowFullscreenObservation {
3061        window_id: usize,
3062        subscription_id: usize,
3063        callback: WindowFullscreenCallback,
3064    },
3065    RefreshWindows,
3066    DispatchActionFrom {
3067        window_id: usize,
3068        view_id: usize,
3069        action: Box<dyn Action>,
3070    },
3071    ActionDispatchNotification {
3072        action_id: TypeId,
3073    },
3074    WindowShouldCloseSubscription {
3075        window_id: usize,
3076        callback: WindowShouldCloseSubscriptionCallback,
3077    },
3078}
3079
3080impl Debug for Effect {
3081    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3082        match self {
3083            Effect::Subscription {
3084                entity_id,
3085                subscription_id,
3086                ..
3087            } => f
3088                .debug_struct("Effect::Subscribe")
3089                .field("entity_id", entity_id)
3090                .field("subscription_id", subscription_id)
3091                .finish(),
3092            Effect::Event { entity_id, .. } => f
3093                .debug_struct("Effect::Event")
3094                .field("entity_id", entity_id)
3095                .finish(),
3096            Effect::GlobalSubscription {
3097                type_id,
3098                subscription_id,
3099                ..
3100            } => f
3101                .debug_struct("Effect::Subscribe")
3102                .field("type_id", type_id)
3103                .field("subscription_id", subscription_id)
3104                .finish(),
3105            Effect::GlobalEvent { payload, .. } => f
3106                .debug_struct("Effect::GlobalEvent")
3107                .field("type_id", &(&*payload).type_id())
3108                .finish(),
3109            Effect::Observation {
3110                entity_id,
3111                subscription_id,
3112                ..
3113            } => f
3114                .debug_struct("Effect::Observation")
3115                .field("entity_id", entity_id)
3116                .field("subscription_id", subscription_id)
3117                .finish(),
3118            Effect::ModelNotification { model_id } => f
3119                .debug_struct("Effect::ModelNotification")
3120                .field("model_id", model_id)
3121                .finish(),
3122            Effect::ViewNotification { window_id, view_id } => f
3123                .debug_struct("Effect::ViewNotification")
3124                .field("window_id", window_id)
3125                .field("view_id", view_id)
3126                .finish(),
3127            Effect::GlobalNotification { type_id } => f
3128                .debug_struct("Effect::GlobalNotification")
3129                .field("type_id", type_id)
3130                .finish(),
3131            Effect::Deferred { .. } => f.debug_struct("Effect::Deferred").finish(),
3132            Effect::ModelRelease { model_id, .. } => f
3133                .debug_struct("Effect::ModelRelease")
3134                .field("model_id", model_id)
3135                .finish(),
3136            Effect::ViewRelease { view_id, .. } => f
3137                .debug_struct("Effect::ViewRelease")
3138                .field("view_id", view_id)
3139                .finish(),
3140            Effect::Focus { window_id, view_id } => f
3141                .debug_struct("Effect::Focus")
3142                .field("window_id", window_id)
3143                .field("view_id", view_id)
3144                .finish(),
3145            Effect::FocusObservation {
3146                view_id,
3147                subscription_id,
3148                ..
3149            } => f
3150                .debug_struct("Effect::FocusObservation")
3151                .field("view_id", view_id)
3152                .field("subscription_id", subscription_id)
3153                .finish(),
3154            Effect::DispatchActionFrom {
3155                window_id, view_id, ..
3156            } => f
3157                .debug_struct("Effect::DispatchActionFrom")
3158                .field("window_id", window_id)
3159                .field("view_id", view_id)
3160                .finish(),
3161            Effect::ActionDispatchNotification { action_id, .. } => f
3162                .debug_struct("Effect::ActionDispatchNotification")
3163                .field("action_id", action_id)
3164                .finish(),
3165            Effect::ResizeWindow { window_id } => f
3166                .debug_struct("Effect::RefreshWindow")
3167                .field("window_id", window_id)
3168                .finish(),
3169            Effect::WindowActivationObservation {
3170                window_id,
3171                subscription_id,
3172                ..
3173            } => f
3174                .debug_struct("Effect::WindowActivationObservation")
3175                .field("window_id", window_id)
3176                .field("subscription_id", subscription_id)
3177                .finish(),
3178            Effect::ActivateWindow {
3179                window_id,
3180                is_active,
3181            } => f
3182                .debug_struct("Effect::ActivateWindow")
3183                .field("window_id", window_id)
3184                .field("is_active", is_active)
3185                .finish(),
3186            Effect::FullscreenWindow {
3187                window_id,
3188                is_fullscreen,
3189            } => f
3190                .debug_struct("Effect::FullscreenWindow")
3191                .field("window_id", window_id)
3192                .field("is_fullscreen", is_fullscreen)
3193                .finish(),
3194            Effect::WindowFullscreenObservation {
3195                window_id,
3196                subscription_id,
3197                callback: _,
3198            } => f
3199                .debug_struct("Effect::WindowFullscreenObservation")
3200                .field("window_id", window_id)
3201                .field("subscription_id", subscription_id)
3202                .finish(),
3203            Effect::RefreshWindows => f.debug_struct("Effect::FullViewRefresh").finish(),
3204            Effect::WindowShouldCloseSubscription { window_id, .. } => f
3205                .debug_struct("Effect::WindowShouldCloseSubscription")
3206                .field("window_id", window_id)
3207                .finish(),
3208        }
3209    }
3210}
3211
3212pub trait AnyModel {
3213    fn as_any(&self) -> &dyn Any;
3214    fn as_any_mut(&mut self) -> &mut dyn Any;
3215    fn release(&mut self, cx: &mut MutableAppContext);
3216    fn app_will_quit(
3217        &mut self,
3218        cx: &mut MutableAppContext,
3219    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
3220}
3221
3222impl<T> AnyModel for T
3223where
3224    T: Entity,
3225{
3226    fn as_any(&self) -> &dyn Any {
3227        self
3228    }
3229
3230    fn as_any_mut(&mut self) -> &mut dyn Any {
3231        self
3232    }
3233
3234    fn release(&mut self, cx: &mut MutableAppContext) {
3235        self.release(cx);
3236    }
3237
3238    fn app_will_quit(
3239        &mut self,
3240        cx: &mut MutableAppContext,
3241    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
3242        self.app_will_quit(cx)
3243    }
3244}
3245
3246pub trait AnyView {
3247    fn as_any(&self) -> &dyn Any;
3248    fn as_any_mut(&mut self) -> &mut dyn Any;
3249    fn release(&mut self, cx: &mut MutableAppContext);
3250    fn app_will_quit(
3251        &mut self,
3252        cx: &mut MutableAppContext,
3253    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
3254    fn ui_name(&self) -> &'static str;
3255    fn render(&mut self, params: RenderParams, cx: &mut MutableAppContext) -> ElementBox;
3256    fn on_focus_in(
3257        &mut self,
3258        cx: &mut MutableAppContext,
3259        window_id: usize,
3260        view_id: usize,
3261        focused_id: usize,
3262    );
3263    fn on_focus_out(
3264        &mut self,
3265        cx: &mut MutableAppContext,
3266        window_id: usize,
3267        view_id: usize,
3268        focused_id: usize,
3269    );
3270    fn keymap_context(&self, cx: &AppContext) -> keymap::Context;
3271    fn debug_json(&self, cx: &AppContext) -> serde_json::Value;
3272
3273    fn text_for_range(&self, range: Range<usize>, cx: &AppContext) -> Option<String>;
3274    fn selected_text_range(&self, cx: &AppContext) -> Option<Range<usize>>;
3275    fn marked_text_range(&self, cx: &AppContext) -> Option<Range<usize>>;
3276    fn unmark_text(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize);
3277    fn replace_text_in_range(
3278        &mut self,
3279        range: Option<Range<usize>>,
3280        text: &str,
3281        cx: &mut MutableAppContext,
3282        window_id: usize,
3283        view_id: usize,
3284    );
3285    fn replace_and_mark_text_in_range(
3286        &mut self,
3287        range: Option<Range<usize>>,
3288        new_text: &str,
3289        new_selected_range: Option<Range<usize>>,
3290        cx: &mut MutableAppContext,
3291        window_id: usize,
3292        view_id: usize,
3293    );
3294    fn any_handle(&self, window_id: usize, view_id: usize, cx: &AppContext) -> AnyViewHandle {
3295        AnyViewHandle::new(
3296            window_id,
3297            view_id,
3298            self.as_any().type_id(),
3299            cx.ref_counts.clone(),
3300        )
3301    }
3302}
3303
3304impl<T> AnyView for T
3305where
3306    T: View,
3307{
3308    fn as_any(&self) -> &dyn Any {
3309        self
3310    }
3311
3312    fn as_any_mut(&mut self) -> &mut dyn Any {
3313        self
3314    }
3315
3316    fn release(&mut self, cx: &mut MutableAppContext) {
3317        self.release(cx);
3318    }
3319
3320    fn app_will_quit(
3321        &mut self,
3322        cx: &mut MutableAppContext,
3323    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
3324        self.app_will_quit(cx)
3325    }
3326
3327    fn ui_name(&self) -> &'static str {
3328        T::ui_name()
3329    }
3330
3331    fn render(&mut self, params: RenderParams, cx: &mut MutableAppContext) -> ElementBox {
3332        View::render(self, &mut RenderContext::new(params, cx))
3333    }
3334
3335    fn on_focus_in(
3336        &mut self,
3337        cx: &mut MutableAppContext,
3338        window_id: usize,
3339        view_id: usize,
3340        focused_id: usize,
3341    ) {
3342        let mut cx = ViewContext::new(cx, window_id, view_id);
3343        let focused_view_handle: AnyViewHandle = if view_id == focused_id {
3344            cx.handle().into()
3345        } else {
3346            let focused_type = cx
3347                .views
3348                .get(&(window_id, focused_id))
3349                .unwrap()
3350                .as_any()
3351                .type_id();
3352            AnyViewHandle::new(window_id, focused_id, focused_type, cx.ref_counts.clone())
3353        };
3354        View::on_focus_in(self, focused_view_handle, &mut cx);
3355    }
3356
3357    fn on_focus_out(
3358        &mut self,
3359        cx: &mut MutableAppContext,
3360        window_id: usize,
3361        view_id: usize,
3362        blurred_id: usize,
3363    ) {
3364        let mut cx = ViewContext::new(cx, window_id, view_id);
3365        let blurred_view_handle: AnyViewHandle = if view_id == blurred_id {
3366            cx.handle().into()
3367        } else {
3368            let blurred_type = cx
3369                .views
3370                .get(&(window_id, blurred_id))
3371                .unwrap()
3372                .as_any()
3373                .type_id();
3374            AnyViewHandle::new(window_id, blurred_id, blurred_type, cx.ref_counts.clone())
3375        };
3376        View::on_focus_out(self, blurred_view_handle, &mut cx);
3377    }
3378
3379    fn keymap_context(&self, cx: &AppContext) -> keymap::Context {
3380        View::keymap_context(self, cx)
3381    }
3382
3383    fn debug_json(&self, cx: &AppContext) -> serde_json::Value {
3384        View::debug_json(self, cx)
3385    }
3386
3387    fn text_for_range(&self, range: Range<usize>, cx: &AppContext) -> Option<String> {
3388        View::text_for_range(self, range, cx)
3389    }
3390
3391    fn selected_text_range(&self, cx: &AppContext) -> Option<Range<usize>> {
3392        View::selected_text_range(self, cx)
3393    }
3394
3395    fn marked_text_range(&self, cx: &AppContext) -> Option<Range<usize>> {
3396        View::marked_text_range(self, cx)
3397    }
3398
3399    fn unmark_text(&mut self, cx: &mut MutableAppContext, window_id: usize, view_id: usize) {
3400        let mut cx = ViewContext::new(cx, window_id, view_id);
3401        View::unmark_text(self, &mut cx)
3402    }
3403
3404    fn replace_text_in_range(
3405        &mut self,
3406        range: Option<Range<usize>>,
3407        text: &str,
3408        cx: &mut MutableAppContext,
3409        window_id: usize,
3410        view_id: usize,
3411    ) {
3412        let mut cx = ViewContext::new(cx, window_id, view_id);
3413        View::replace_text_in_range(self, range, text, &mut cx)
3414    }
3415
3416    fn replace_and_mark_text_in_range(
3417        &mut self,
3418        range: Option<Range<usize>>,
3419        new_text: &str,
3420        new_selected_range: Option<Range<usize>>,
3421        cx: &mut MutableAppContext,
3422        window_id: usize,
3423        view_id: usize,
3424    ) {
3425        let mut cx = ViewContext::new(cx, window_id, view_id);
3426        View::replace_and_mark_text_in_range(self, range, new_text, new_selected_range, &mut cx)
3427    }
3428}
3429
3430pub struct ModelContext<'a, T: ?Sized> {
3431    app: &'a mut MutableAppContext,
3432    model_id: usize,
3433    model_type: PhantomData<T>,
3434    halt_stream: bool,
3435}
3436
3437impl<'a, T: Entity> ModelContext<'a, T> {
3438    fn new(app: &'a mut MutableAppContext, model_id: usize) -> Self {
3439        Self {
3440            app,
3441            model_id,
3442            model_type: PhantomData,
3443            halt_stream: false,
3444        }
3445    }
3446
3447    pub fn background(&self) -> &Arc<executor::Background> {
3448        &self.app.cx.background
3449    }
3450
3451    pub fn halt_stream(&mut self) {
3452        self.halt_stream = true;
3453    }
3454
3455    pub fn model_id(&self) -> usize {
3456        self.model_id
3457    }
3458
3459    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
3460    where
3461        S: Entity,
3462        F: FnOnce(&mut ModelContext<S>) -> S,
3463    {
3464        self.app.add_model(build_model)
3465    }
3466
3467    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut T, &mut ModelContext<T>)) {
3468        let handle = self.handle();
3469        self.app.defer(move |cx| {
3470            handle.update(cx, |model, cx| {
3471                callback(model, cx);
3472            })
3473        })
3474    }
3475
3476    pub fn emit(&mut self, payload: T::Event) {
3477        self.app.pending_effects.push_back(Effect::Event {
3478            entity_id: self.model_id,
3479            payload: Box::new(payload),
3480        });
3481    }
3482
3483    pub fn notify(&mut self) {
3484        self.app.notify_model(self.model_id);
3485    }
3486
3487    pub fn subscribe<S: Entity, F>(
3488        &mut self,
3489        handle: &ModelHandle<S>,
3490        mut callback: F,
3491    ) -> Subscription
3492    where
3493        S::Event: 'static,
3494        F: 'static + FnMut(&mut T, ModelHandle<S>, &S::Event, &mut ModelContext<T>),
3495    {
3496        let subscriber = self.weak_handle();
3497        self.app
3498            .subscribe_internal(handle, move |emitter, event, cx| {
3499                if let Some(subscriber) = subscriber.upgrade(cx) {
3500                    subscriber.update(cx, |subscriber, cx| {
3501                        callback(subscriber, emitter, event, cx);
3502                    });
3503                    true
3504                } else {
3505                    false
3506                }
3507            })
3508    }
3509
3510    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F) -> Subscription
3511    where
3512        S: Entity,
3513        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
3514    {
3515        let observer = self.weak_handle();
3516        self.app.observe_internal(handle, move |observed, cx| {
3517            if let Some(observer) = observer.upgrade(cx) {
3518                observer.update(cx, |observer, cx| {
3519                    callback(observer, observed, cx);
3520                });
3521                true
3522            } else {
3523                false
3524            }
3525        })
3526    }
3527
3528    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
3529    where
3530        G: Any,
3531        F: 'static + FnMut(&mut T, &mut ModelContext<T>),
3532    {
3533        let observer = self.weak_handle();
3534        self.app.observe_global::<G, _>(move |cx| {
3535            if let Some(observer) = observer.upgrade(cx) {
3536                observer.update(cx, |observer, cx| callback(observer, cx));
3537            }
3538        })
3539    }
3540
3541    pub fn observe_release<S, F>(
3542        &mut self,
3543        handle: &ModelHandle<S>,
3544        mut callback: F,
3545    ) -> Subscription
3546    where
3547        S: Entity,
3548        F: 'static + FnMut(&mut T, &S, &mut ModelContext<T>),
3549    {
3550        let observer = self.weak_handle();
3551        self.app.observe_release(handle, move |released, cx| {
3552            if let Some(observer) = observer.upgrade(cx) {
3553                observer.update(cx, |observer, cx| {
3554                    callback(observer, released, cx);
3555                });
3556            }
3557        })
3558    }
3559
3560    pub fn handle(&self) -> ModelHandle<T> {
3561        ModelHandle::new(self.model_id, &self.app.cx.ref_counts)
3562    }
3563
3564    pub fn weak_handle(&self) -> WeakModelHandle<T> {
3565        WeakModelHandle::new(self.model_id)
3566    }
3567
3568    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
3569    where
3570        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
3571        Fut: 'static + Future<Output = S>,
3572        S: 'static,
3573    {
3574        let handle = self.handle();
3575        self.app.spawn(|cx| f(handle, cx))
3576    }
3577
3578    pub fn spawn_weak<F, Fut, S>(&self, f: F) -> Task<S>
3579    where
3580        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
3581        Fut: 'static + Future<Output = S>,
3582        S: 'static,
3583    {
3584        let handle = self.weak_handle();
3585        self.app.spawn(|cx| f(handle, cx))
3586    }
3587}
3588
3589impl<M> AsRef<AppContext> for ModelContext<'_, M> {
3590    fn as_ref(&self) -> &AppContext {
3591        &self.app.cx
3592    }
3593}
3594
3595impl<M> AsMut<MutableAppContext> for ModelContext<'_, M> {
3596    fn as_mut(&mut self) -> &mut MutableAppContext {
3597        self.app
3598    }
3599}
3600
3601impl<M> ReadModel for ModelContext<'_, M> {
3602    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
3603        self.app.read_model(handle)
3604    }
3605}
3606
3607impl<M> UpdateModel for ModelContext<'_, M> {
3608    fn update_model<T: Entity, V>(
3609        &mut self,
3610        handle: &ModelHandle<T>,
3611        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
3612    ) -> V {
3613        self.app.update_model(handle, update)
3614    }
3615}
3616
3617impl<M> UpgradeModelHandle for ModelContext<'_, M> {
3618    fn upgrade_model_handle<T: Entity>(
3619        &self,
3620        handle: &WeakModelHandle<T>,
3621    ) -> Option<ModelHandle<T>> {
3622        self.cx.upgrade_model_handle(handle)
3623    }
3624
3625    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
3626        self.cx.model_handle_is_upgradable(handle)
3627    }
3628
3629    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
3630        self.cx.upgrade_any_model_handle(handle)
3631    }
3632}
3633
3634impl<M> Deref for ModelContext<'_, M> {
3635    type Target = MutableAppContext;
3636
3637    fn deref(&self) -> &Self::Target {
3638        self.app
3639    }
3640}
3641
3642impl<M> DerefMut for ModelContext<'_, M> {
3643    fn deref_mut(&mut self) -> &mut Self::Target {
3644        &mut self.app
3645    }
3646}
3647
3648pub struct ViewContext<'a, T: ?Sized> {
3649    app: &'a mut MutableAppContext,
3650    window_id: usize,
3651    view_id: usize,
3652    view_type: PhantomData<T>,
3653}
3654
3655impl<'a, T: View> ViewContext<'a, T> {
3656    fn new(app: &'a mut MutableAppContext, window_id: usize, view_id: usize) -> Self {
3657        Self {
3658            app,
3659            window_id,
3660            view_id,
3661            view_type: PhantomData,
3662        }
3663    }
3664
3665    pub fn handle(&self) -> ViewHandle<T> {
3666        ViewHandle::new(self.window_id, self.view_id, &self.app.cx.ref_counts)
3667    }
3668
3669    pub fn weak_handle(&self) -> WeakViewHandle<T> {
3670        WeakViewHandle::new(self.window_id, self.view_id)
3671    }
3672
3673    pub fn window_id(&self) -> usize {
3674        self.window_id
3675    }
3676
3677    pub fn view_id(&self) -> usize {
3678        self.view_id
3679    }
3680
3681    pub fn foreground(&self) -> &Rc<executor::Foreground> {
3682        self.app.foreground()
3683    }
3684
3685    pub fn background_executor(&self) -> &Arc<executor::Background> {
3686        &self.app.cx.background
3687    }
3688
3689    pub fn platform(&self) -> Arc<dyn Platform> {
3690        self.app.platform()
3691    }
3692
3693    pub fn show_character_palette(&self) {
3694        self.app.show_character_palette(self.window_id);
3695    }
3696
3697    pub fn minimize_window(&self) {
3698        self.app.minimize_window(self.window_id)
3699    }
3700
3701    pub fn zoom_window(&self) {
3702        self.app.zoom_window(self.window_id)
3703    }
3704
3705    pub fn toggle_full_screen(&self) {
3706        self.app.toggle_window_full_screen(self.window_id)
3707    }
3708
3709    pub fn prompt(
3710        &self,
3711        level: PromptLevel,
3712        msg: &str,
3713        answers: &[&str],
3714    ) -> oneshot::Receiver<usize> {
3715        self.app.prompt(self.window_id, level, msg, answers)
3716    }
3717
3718    pub fn prompt_for_paths(
3719        &self,
3720        options: PathPromptOptions,
3721    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
3722        self.app.prompt_for_paths(options)
3723    }
3724
3725    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
3726        self.app.prompt_for_new_path(directory)
3727    }
3728
3729    pub fn debug_elements(&self) -> crate::json::Value {
3730        self.app.debug_elements(self.window_id).unwrap()
3731    }
3732
3733    pub fn focus<S>(&mut self, handle: S)
3734    where
3735        S: Into<AnyViewHandle>,
3736    {
3737        let handle = handle.into();
3738        self.app.focus(handle.window_id, Some(handle.view_id));
3739    }
3740
3741    pub fn focus_self(&mut self) {
3742        self.app.focus(self.window_id, Some(self.view_id));
3743    }
3744
3745    pub fn is_self_focused(&self) -> bool {
3746        self.app.focused_view_id(self.window_id) == Some(self.view_id)
3747    }
3748
3749    pub fn blur(&mut self) {
3750        self.app.focus(self.window_id, None);
3751    }
3752
3753    pub fn set_window_title(&mut self, title: &str) {
3754        let window_id = self.window_id();
3755        if let Some((_, window)) = self.presenters_and_platform_windows.get_mut(&window_id) {
3756            window.set_title(title);
3757        }
3758    }
3759
3760    pub fn set_window_edited(&mut self, edited: bool) {
3761        let window_id = self.window_id();
3762        if let Some((_, window)) = self.presenters_and_platform_windows.get_mut(&window_id) {
3763            window.set_edited(edited);
3764        }
3765    }
3766
3767    pub fn on_window_should_close<F>(&mut self, mut callback: F)
3768    where
3769        F: 'static + FnMut(&mut T, &mut ViewContext<T>) -> bool,
3770    {
3771        let window_id = self.window_id();
3772        let view = self.weak_handle();
3773        self.pending_effects
3774            .push_back(Effect::WindowShouldCloseSubscription {
3775                window_id,
3776                callback: Box::new(move |cx| {
3777                    if let Some(view) = view.upgrade(cx) {
3778                        view.update(cx, |view, cx| callback(view, cx))
3779                    } else {
3780                        true
3781                    }
3782                }),
3783            });
3784    }
3785
3786    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
3787    where
3788        S: Entity,
3789        F: FnOnce(&mut ModelContext<S>) -> S,
3790    {
3791        self.app.add_model(build_model)
3792    }
3793
3794    pub fn add_view<S, F>(&mut self, build_view: F) -> ViewHandle<S>
3795    where
3796        S: View,
3797        F: FnOnce(&mut ViewContext<S>) -> S,
3798    {
3799        self.app
3800            .build_and_insert_view(self.window_id, ParentId::View(self.view_id), |cx| {
3801                Some(build_view(cx))
3802            })
3803            .unwrap()
3804    }
3805
3806    pub fn add_option_view<S, F>(&mut self, build_view: F) -> Option<ViewHandle<S>>
3807    where
3808        S: View,
3809        F: FnOnce(&mut ViewContext<S>) -> Option<S>,
3810    {
3811        self.app
3812            .build_and_insert_view(self.window_id, ParentId::View(self.view_id), build_view)
3813    }
3814
3815    pub fn reparent(&mut self, view_handle: impl Into<AnyViewHandle>) {
3816        let view_handle = view_handle.into();
3817        if self.window_id != view_handle.window_id {
3818            panic!("Can't reparent view to a view from a different window");
3819        }
3820        self.cx
3821            .parents
3822            .remove(&(view_handle.window_id, view_handle.view_id));
3823        let new_parent_id = self.view_id;
3824        self.cx.parents.insert(
3825            (view_handle.window_id, view_handle.view_id),
3826            ParentId::View(new_parent_id),
3827        );
3828    }
3829
3830    pub fn replace_root_view<V, F>(&mut self, build_root_view: F) -> ViewHandle<V>
3831    where
3832        V: View,
3833        F: FnOnce(&mut ViewContext<V>) -> V,
3834    {
3835        let window_id = self.window_id;
3836        self.update(|this| {
3837            let root_view = this
3838                .build_and_insert_view(window_id, ParentId::Root, |cx| Some(build_root_view(cx)))
3839                .unwrap();
3840            let window = this.cx.windows.get_mut(&window_id).unwrap();
3841            window.root_view = root_view.clone().into();
3842            window.focused_view_id = Some(root_view.id());
3843            root_view
3844        })
3845    }
3846
3847    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
3848    where
3849        E: Entity,
3850        E::Event: 'static,
3851        H: Handle<E>,
3852        F: 'static + FnMut(&mut T, H, &E::Event, &mut ViewContext<T>),
3853    {
3854        let subscriber = self.weak_handle();
3855        self.app
3856            .subscribe_internal(handle, move |emitter, event, cx| {
3857                if let Some(subscriber) = subscriber.upgrade(cx) {
3858                    subscriber.update(cx, |subscriber, cx| {
3859                        callback(subscriber, emitter, event, cx);
3860                    });
3861                    true
3862                } else {
3863                    false
3864                }
3865            })
3866    }
3867
3868    pub fn observe<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3869    where
3870        E: Entity,
3871        H: Handle<E>,
3872        F: 'static + FnMut(&mut T, H, &mut ViewContext<T>),
3873    {
3874        let observer = self.weak_handle();
3875        self.app.observe_internal(handle, move |observed, cx| {
3876            if let Some(observer) = observer.upgrade(cx) {
3877                observer.update(cx, |observer, cx| {
3878                    callback(observer, observed, cx);
3879                });
3880                true
3881            } else {
3882                false
3883            }
3884        })
3885    }
3886
3887    pub fn observe_focus<F, V>(&mut self, handle: &ViewHandle<V>, mut callback: F) -> Subscription
3888    where
3889        F: 'static + FnMut(&mut T, ViewHandle<V>, bool, &mut ViewContext<T>),
3890        V: View,
3891    {
3892        let observer = self.weak_handle();
3893        self.app
3894            .observe_focus(handle, move |observed, focused, cx| {
3895                if let Some(observer) = observer.upgrade(cx) {
3896                    observer.update(cx, |observer, cx| {
3897                        callback(observer, observed, focused, cx);
3898                    });
3899                    true
3900                } else {
3901                    false
3902                }
3903            })
3904    }
3905
3906    pub fn observe_release<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3907    where
3908        E: Entity,
3909        H: Handle<E>,
3910        F: 'static + FnMut(&mut T, &E, &mut ViewContext<T>),
3911    {
3912        let observer = self.weak_handle();
3913        self.app.observe_release(handle, move |released, cx| {
3914            if let Some(observer) = observer.upgrade(cx) {
3915                observer.update(cx, |observer, cx| {
3916                    callback(observer, released, cx);
3917                });
3918            }
3919        })
3920    }
3921
3922    pub fn observe_actions<F>(&mut self, mut callback: F) -> Subscription
3923    where
3924        F: 'static + FnMut(&mut T, TypeId, &mut ViewContext<T>),
3925    {
3926        let observer = self.weak_handle();
3927        self.app.observe_actions(move |action_id, cx| {
3928            if let Some(observer) = observer.upgrade(cx) {
3929                observer.update(cx, |observer, cx| {
3930                    callback(observer, action_id, cx);
3931                });
3932            }
3933        })
3934    }
3935
3936    pub fn observe_window_activation<F>(&mut self, mut callback: F) -> Subscription
3937    where
3938        F: 'static + FnMut(&mut T, bool, &mut ViewContext<T>),
3939    {
3940        let observer = self.weak_handle();
3941        self.app
3942            .observe_window_activation(self.window_id(), move |active, cx| {
3943                if let Some(observer) = observer.upgrade(cx) {
3944                    observer.update(cx, |observer, cx| {
3945                        callback(observer, active, cx);
3946                    });
3947                    true
3948                } else {
3949                    false
3950                }
3951            })
3952    }
3953
3954    pub fn observe_fullscreen<F>(&mut self, mut callback: F) -> Subscription
3955    where
3956        F: 'static + FnMut(&mut T, bool, &mut ViewContext<T>),
3957    {
3958        let observer = self.weak_handle();
3959        self.app
3960            .observe_fullscreen(self.window_id(), move |active, cx| {
3961                if let Some(observer) = observer.upgrade(cx) {
3962                    observer.update(cx, |observer, cx| {
3963                        callback(observer, active, cx);
3964                    });
3965                    true
3966                } else {
3967                    false
3968                }
3969            })
3970    }
3971
3972    pub fn emit(&mut self, payload: T::Event) {
3973        self.app.pending_effects.push_back(Effect::Event {
3974            entity_id: self.view_id,
3975            payload: Box::new(payload),
3976        });
3977    }
3978
3979    pub fn notify(&mut self) {
3980        self.app.notify_view(self.window_id, self.view_id);
3981    }
3982
3983    pub fn dispatch_any_action(&mut self, action: Box<dyn Action>) {
3984        self.app
3985            .dispatch_any_action_at(self.window_id, self.view_id, action)
3986    }
3987
3988    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut T, &mut ViewContext<T>)) {
3989        let handle = self.handle();
3990        self.app.defer(move |cx| {
3991            handle.update(cx, |view, cx| {
3992                callback(view, cx);
3993            })
3994        })
3995    }
3996
3997    pub fn after_window_update(
3998        &mut self,
3999        callback: impl 'static + FnOnce(&mut T, &mut ViewContext<T>),
4000    ) {
4001        let handle = self.handle();
4002        self.app.after_window_update(move |cx| {
4003            handle.update(cx, |view, cx| {
4004                callback(view, cx);
4005            })
4006        })
4007    }
4008
4009    pub fn propagate_action(&mut self) {
4010        self.app.halt_action_dispatch = false;
4011    }
4012
4013    pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
4014    where
4015        F: FnOnce(ViewHandle<T>, AsyncAppContext) -> Fut,
4016        Fut: 'static + Future<Output = S>,
4017        S: 'static,
4018    {
4019        let handle = self.handle();
4020        self.app.spawn(|cx| f(handle, cx))
4021    }
4022
4023    pub fn spawn_weak<F, Fut, S>(&self, f: F) -> Task<S>
4024    where
4025        F: FnOnce(WeakViewHandle<T>, AsyncAppContext) -> Fut,
4026        Fut: 'static + Future<Output = S>,
4027        S: 'static,
4028    {
4029        let handle = self.weak_handle();
4030        self.app.spawn(|cx| f(handle, cx))
4031    }
4032}
4033
4034pub struct RenderParams {
4035    pub window_id: usize,
4036    pub view_id: usize,
4037    pub titlebar_height: f32,
4038    pub hovered_region_ids: HashSet<MouseRegionId>,
4039    pub clicked_region_ids: Option<(Vec<MouseRegionId>, MouseButton)>,
4040    pub refreshing: bool,
4041}
4042
4043pub struct RenderContext<'a, T: View> {
4044    pub(crate) window_id: usize,
4045    pub(crate) view_id: usize,
4046    pub(crate) view_type: PhantomData<T>,
4047    pub(crate) hovered_region_ids: HashSet<MouseRegionId>,
4048    pub(crate) clicked_region_ids: Option<(Vec<MouseRegionId>, MouseButton)>,
4049    pub app: &'a mut MutableAppContext,
4050    pub titlebar_height: f32,
4051    pub refreshing: bool,
4052}
4053
4054#[derive(Clone, Copy, Default)]
4055pub struct MouseState {
4056    pub hovered: bool,
4057    pub clicked: Option<MouseButton>,
4058}
4059
4060impl<'a, V: View> RenderContext<'a, V> {
4061    fn new(params: RenderParams, app: &'a mut MutableAppContext) -> Self {
4062        Self {
4063            app,
4064            window_id: params.window_id,
4065            view_id: params.view_id,
4066            view_type: PhantomData,
4067            titlebar_height: params.titlebar_height,
4068            hovered_region_ids: params.hovered_region_ids.clone(),
4069            clicked_region_ids: params.clicked_region_ids.clone(),
4070            refreshing: params.refreshing,
4071        }
4072    }
4073
4074    pub fn handle(&self) -> WeakViewHandle<V> {
4075        WeakViewHandle::new(self.window_id, self.view_id)
4076    }
4077
4078    pub fn window_id(&self) -> usize {
4079        self.window_id
4080    }
4081
4082    pub fn view_id(&self) -> usize {
4083        self.view_id
4084    }
4085
4086    pub fn mouse_state<Tag: 'static>(&self, region_id: usize) -> MouseState {
4087        let region_id = MouseRegionId {
4088            view_id: self.view_id,
4089            discriminant: (TypeId::of::<Tag>(), region_id),
4090        };
4091        MouseState {
4092            hovered: self.hovered_region_ids.contains(&region_id),
4093            clicked: self.clicked_region_ids.as_ref().and_then(|(ids, button)| {
4094                if ids.contains(&region_id) {
4095                    Some(*button)
4096                } else {
4097                    None
4098                }
4099            }),
4100        }
4101    }
4102
4103    pub fn element_state<Tag: 'static, T: 'static + Default>(
4104        &mut self,
4105        element_id: usize,
4106    ) -> ElementStateHandle<T> {
4107        let id = ElementStateId {
4108            view_id: self.view_id(),
4109            element_id,
4110            tag: TypeId::of::<Tag>(),
4111        };
4112        self.cx
4113            .element_states
4114            .entry(id)
4115            .or_insert_with(|| Box::new(T::default()));
4116        ElementStateHandle::new(id, self.frame_count, &self.cx.ref_counts)
4117    }
4118}
4119
4120impl AsRef<AppContext> for &AppContext {
4121    fn as_ref(&self) -> &AppContext {
4122        self
4123    }
4124}
4125
4126impl<V: View> Deref for RenderContext<'_, V> {
4127    type Target = MutableAppContext;
4128
4129    fn deref(&self) -> &Self::Target {
4130        self.app
4131    }
4132}
4133
4134impl<V: View> DerefMut for RenderContext<'_, V> {
4135    fn deref_mut(&mut self) -> &mut Self::Target {
4136        self.app
4137    }
4138}
4139
4140impl<V: View> ReadModel for RenderContext<'_, V> {
4141    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
4142        self.app.read_model(handle)
4143    }
4144}
4145
4146impl<V: View> UpdateModel for RenderContext<'_, V> {
4147    fn update_model<T: Entity, O>(
4148        &mut self,
4149        handle: &ModelHandle<T>,
4150        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
4151    ) -> O {
4152        self.app.update_model(handle, update)
4153    }
4154}
4155
4156impl<V: View> ReadView for RenderContext<'_, V> {
4157    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
4158        self.app.read_view(handle)
4159    }
4160}
4161
4162impl<M> AsRef<AppContext> for ViewContext<'_, M> {
4163    fn as_ref(&self) -> &AppContext {
4164        &self.app.cx
4165    }
4166}
4167
4168impl<M> Deref for ViewContext<'_, M> {
4169    type Target = MutableAppContext;
4170
4171    fn deref(&self) -> &Self::Target {
4172        self.app
4173    }
4174}
4175
4176impl<M> DerefMut for ViewContext<'_, M> {
4177    fn deref_mut(&mut self) -> &mut Self::Target {
4178        &mut self.app
4179    }
4180}
4181
4182impl<M> AsMut<MutableAppContext> for ViewContext<'_, M> {
4183    fn as_mut(&mut self) -> &mut MutableAppContext {
4184        self.app
4185    }
4186}
4187
4188impl<V> ReadModel for ViewContext<'_, V> {
4189    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
4190        self.app.read_model(handle)
4191    }
4192}
4193
4194impl<V> UpgradeModelHandle for ViewContext<'_, V> {
4195    fn upgrade_model_handle<T: Entity>(
4196        &self,
4197        handle: &WeakModelHandle<T>,
4198    ) -> Option<ModelHandle<T>> {
4199        self.cx.upgrade_model_handle(handle)
4200    }
4201
4202    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
4203        self.cx.model_handle_is_upgradable(handle)
4204    }
4205
4206    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
4207        self.cx.upgrade_any_model_handle(handle)
4208    }
4209}
4210
4211impl<V> UpgradeViewHandle for ViewContext<'_, V> {
4212    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
4213        self.cx.upgrade_view_handle(handle)
4214    }
4215
4216    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
4217        self.cx.upgrade_any_view_handle(handle)
4218    }
4219}
4220
4221impl<V: View> UpgradeViewHandle for RenderContext<'_, V> {
4222    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
4223        self.cx.upgrade_view_handle(handle)
4224    }
4225
4226    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
4227        self.cx.upgrade_any_view_handle(handle)
4228    }
4229}
4230
4231impl<V: View> UpdateModel for ViewContext<'_, V> {
4232    fn update_model<T: Entity, O>(
4233        &mut self,
4234        handle: &ModelHandle<T>,
4235        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
4236    ) -> O {
4237        self.app.update_model(handle, update)
4238    }
4239}
4240
4241impl<V: View> ReadView for ViewContext<'_, V> {
4242    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
4243        self.app.read_view(handle)
4244    }
4245}
4246
4247impl<V: View> UpdateView for ViewContext<'_, V> {
4248    fn update_view<T, S>(
4249        &mut self,
4250        handle: &ViewHandle<T>,
4251        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
4252    ) -> S
4253    where
4254        T: View,
4255    {
4256        self.app.update_view(handle, update)
4257    }
4258}
4259
4260pub trait Handle<T> {
4261    type Weak: 'static;
4262    fn id(&self) -> usize;
4263    fn location(&self) -> EntityLocation;
4264    fn downgrade(&self) -> Self::Weak;
4265    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
4266    where
4267        Self: Sized;
4268}
4269
4270pub trait WeakHandle {
4271    fn id(&self) -> usize;
4272}
4273
4274#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
4275pub enum EntityLocation {
4276    Model(usize),
4277    View(usize, usize),
4278}
4279
4280pub struct ModelHandle<T: Entity> {
4281    model_id: usize,
4282    model_type: PhantomData<T>,
4283    ref_counts: Arc<Mutex<RefCounts>>,
4284
4285    #[cfg(any(test, feature = "test-support"))]
4286    handle_id: usize,
4287}
4288
4289impl<T: Entity> ModelHandle<T> {
4290    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
4291        ref_counts.lock().inc_model(model_id);
4292
4293        #[cfg(any(test, feature = "test-support"))]
4294        let handle_id = ref_counts
4295            .lock()
4296            .leak_detector
4297            .lock()
4298            .handle_created(Some(type_name::<T>()), model_id);
4299
4300        Self {
4301            model_id,
4302            model_type: PhantomData,
4303            ref_counts: ref_counts.clone(),
4304
4305            #[cfg(any(test, feature = "test-support"))]
4306            handle_id,
4307        }
4308    }
4309
4310    pub fn downgrade(&self) -> WeakModelHandle<T> {
4311        WeakModelHandle::new(self.model_id)
4312    }
4313
4314    pub fn id(&self) -> usize {
4315        self.model_id
4316    }
4317
4318    pub fn read<'a, C: ReadModel>(&self, cx: &'a C) -> &'a T {
4319        cx.read_model(self)
4320    }
4321
4322    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
4323    where
4324        C: ReadModelWith,
4325        F: FnOnce(&T, &AppContext) -> S,
4326    {
4327        let mut read = Some(read);
4328        cx.read_model_with(self, &mut |model, cx| {
4329            let read = read.take().unwrap();
4330            read(model, cx)
4331        })
4332    }
4333
4334    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
4335    where
4336        C: UpdateModel,
4337        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
4338    {
4339        let mut update = Some(update);
4340        cx.update_model(self, &mut |model, cx| {
4341            let update = update.take().unwrap();
4342            update(model, cx)
4343        })
4344    }
4345
4346    #[cfg(any(test, feature = "test-support"))]
4347    pub fn next_notification(&self, cx: &TestAppContext) -> impl Future<Output = ()> {
4348        let (tx, mut rx) = futures::channel::mpsc::unbounded();
4349        let mut cx = cx.cx.borrow_mut();
4350        let subscription = cx.observe(self, move |_, _| {
4351            tx.unbounded_send(()).ok();
4352        });
4353
4354        let duration = if std::env::var("CI").is_ok() {
4355            Duration::from_secs(5)
4356        } else {
4357            Duration::from_secs(1)
4358        };
4359
4360        async move {
4361            let notification = crate::util::timeout(duration, rx.next())
4362                .await
4363                .expect("next notification timed out");
4364            drop(subscription);
4365            notification.expect("model dropped while test was waiting for its next notification")
4366        }
4367    }
4368
4369    #[cfg(any(test, feature = "test-support"))]
4370    pub fn next_event(&self, cx: &TestAppContext) -> impl Future<Output = T::Event>
4371    where
4372        T::Event: Clone,
4373    {
4374        let (tx, mut rx) = futures::channel::mpsc::unbounded();
4375        let mut cx = cx.cx.borrow_mut();
4376        let subscription = cx.subscribe(self, move |_, event, _| {
4377            tx.unbounded_send(event.clone()).ok();
4378        });
4379
4380        let duration = if std::env::var("CI").is_ok() {
4381            Duration::from_secs(5)
4382        } else {
4383            Duration::from_secs(1)
4384        };
4385
4386        cx.foreground.start_waiting();
4387        async move {
4388            let event = crate::util::timeout(duration, rx.next())
4389                .await
4390                .expect("next event timed out");
4391            drop(subscription);
4392            event.expect("model dropped while test was waiting for its next event")
4393        }
4394    }
4395
4396    #[cfg(any(test, feature = "test-support"))]
4397    pub fn condition(
4398        &self,
4399        cx: &TestAppContext,
4400        mut predicate: impl FnMut(&T, &AppContext) -> bool,
4401    ) -> impl Future<Output = ()> {
4402        let (tx, mut rx) = futures::channel::mpsc::unbounded();
4403
4404        let mut cx = cx.cx.borrow_mut();
4405        let subscriptions = (
4406            cx.observe(self, {
4407                let tx = tx.clone();
4408                move |_, _| {
4409                    tx.unbounded_send(()).ok();
4410                }
4411            }),
4412            cx.subscribe(self, {
4413                move |_, _, _| {
4414                    tx.unbounded_send(()).ok();
4415                }
4416            }),
4417        );
4418
4419        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
4420        let handle = self.downgrade();
4421        let duration = if std::env::var("CI").is_ok() {
4422            Duration::from_secs(5)
4423        } else {
4424            Duration::from_secs(1)
4425        };
4426
4427        async move {
4428            crate::util::timeout(duration, async move {
4429                loop {
4430                    {
4431                        let cx = cx.borrow();
4432                        let cx = cx.as_ref();
4433                        if predicate(
4434                            handle
4435                                .upgrade(cx)
4436                                .expect("model dropped with pending condition")
4437                                .read(cx),
4438                            cx,
4439                        ) {
4440                            break;
4441                        }
4442                    }
4443
4444                    cx.borrow().foreground().start_waiting();
4445                    rx.next()
4446                        .await
4447                        .expect("model dropped with pending condition");
4448                    cx.borrow().foreground().finish_waiting();
4449                }
4450            })
4451            .await
4452            .expect("condition timed out");
4453            drop(subscriptions);
4454        }
4455    }
4456}
4457
4458impl<T: Entity> Clone for ModelHandle<T> {
4459    fn clone(&self) -> Self {
4460        Self::new(self.model_id, &self.ref_counts)
4461    }
4462}
4463
4464impl<T: Entity> PartialEq for ModelHandle<T> {
4465    fn eq(&self, other: &Self) -> bool {
4466        self.model_id == other.model_id
4467    }
4468}
4469
4470impl<T: Entity> Eq for ModelHandle<T> {}
4471
4472impl<T: Entity> PartialEq<WeakModelHandle<T>> for ModelHandle<T> {
4473    fn eq(&self, other: &WeakModelHandle<T>) -> bool {
4474        self.model_id == other.model_id
4475    }
4476}
4477
4478impl<T: Entity> Hash for ModelHandle<T> {
4479    fn hash<H: Hasher>(&self, state: &mut H) {
4480        self.model_id.hash(state);
4481    }
4482}
4483
4484impl<T: Entity> std::borrow::Borrow<usize> for ModelHandle<T> {
4485    fn borrow(&self) -> &usize {
4486        &self.model_id
4487    }
4488}
4489
4490impl<T: Entity> Debug for ModelHandle<T> {
4491    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4492        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
4493            .field(&self.model_id)
4494            .finish()
4495    }
4496}
4497
4498unsafe impl<T: Entity> Send for ModelHandle<T> {}
4499unsafe impl<T: Entity> Sync for ModelHandle<T> {}
4500
4501impl<T: Entity> Drop for ModelHandle<T> {
4502    fn drop(&mut self) {
4503        let mut ref_counts = self.ref_counts.lock();
4504        ref_counts.dec_model(self.model_id);
4505
4506        #[cfg(any(test, feature = "test-support"))]
4507        ref_counts
4508            .leak_detector
4509            .lock()
4510            .handle_dropped(self.model_id, self.handle_id);
4511    }
4512}
4513
4514impl<T: Entity> Handle<T> for ModelHandle<T> {
4515    type Weak = WeakModelHandle<T>;
4516
4517    fn id(&self) -> usize {
4518        self.model_id
4519    }
4520
4521    fn location(&self) -> EntityLocation {
4522        EntityLocation::Model(self.model_id)
4523    }
4524
4525    fn downgrade(&self) -> Self::Weak {
4526        self.downgrade()
4527    }
4528
4529    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
4530    where
4531        Self: Sized,
4532    {
4533        weak.upgrade(cx)
4534    }
4535}
4536
4537pub struct WeakModelHandle<T> {
4538    model_id: usize,
4539    model_type: PhantomData<T>,
4540}
4541
4542impl<T> WeakHandle for WeakModelHandle<T> {
4543    fn id(&self) -> usize {
4544        self.model_id
4545    }
4546}
4547
4548unsafe impl<T> Send for WeakModelHandle<T> {}
4549unsafe impl<T> Sync for WeakModelHandle<T> {}
4550
4551impl<T: Entity> WeakModelHandle<T> {
4552    fn new(model_id: usize) -> Self {
4553        Self {
4554            model_id,
4555            model_type: PhantomData,
4556        }
4557    }
4558
4559    pub fn id(&self) -> usize {
4560        self.model_id
4561    }
4562
4563    pub fn is_upgradable(&self, cx: &impl UpgradeModelHandle) -> bool {
4564        cx.model_handle_is_upgradable(self)
4565    }
4566
4567    pub fn upgrade(&self, cx: &impl UpgradeModelHandle) -> Option<ModelHandle<T>> {
4568        cx.upgrade_model_handle(self)
4569    }
4570}
4571
4572impl<T> Hash for WeakModelHandle<T> {
4573    fn hash<H: Hasher>(&self, state: &mut H) {
4574        self.model_id.hash(state)
4575    }
4576}
4577
4578impl<T> PartialEq for WeakModelHandle<T> {
4579    fn eq(&self, other: &Self) -> bool {
4580        self.model_id == other.model_id
4581    }
4582}
4583
4584impl<T> Eq for WeakModelHandle<T> {}
4585
4586impl<T> Clone for WeakModelHandle<T> {
4587    fn clone(&self) -> Self {
4588        Self {
4589            model_id: self.model_id,
4590            model_type: PhantomData,
4591        }
4592    }
4593}
4594
4595impl<T> Copy for WeakModelHandle<T> {}
4596
4597pub struct ViewHandle<T> {
4598    window_id: usize,
4599    view_id: usize,
4600    view_type: PhantomData<T>,
4601    ref_counts: Arc<Mutex<RefCounts>>,
4602    #[cfg(any(test, feature = "test-support"))]
4603    handle_id: usize,
4604}
4605
4606impl<T: View> ViewHandle<T> {
4607    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
4608        ref_counts.lock().inc_view(window_id, view_id);
4609        #[cfg(any(test, feature = "test-support"))]
4610        let handle_id = ref_counts
4611            .lock()
4612            .leak_detector
4613            .lock()
4614            .handle_created(Some(type_name::<T>()), view_id);
4615
4616        Self {
4617            window_id,
4618            view_id,
4619            view_type: PhantomData,
4620            ref_counts: ref_counts.clone(),
4621
4622            #[cfg(any(test, feature = "test-support"))]
4623            handle_id,
4624        }
4625    }
4626
4627    pub fn downgrade(&self) -> WeakViewHandle<T> {
4628        WeakViewHandle::new(self.window_id, self.view_id)
4629    }
4630
4631    pub fn window_id(&self) -> usize {
4632        self.window_id
4633    }
4634
4635    pub fn id(&self) -> usize {
4636        self.view_id
4637    }
4638
4639    pub fn read<'a, C: ReadView>(&self, cx: &'a C) -> &'a T {
4640        cx.read_view(self)
4641    }
4642
4643    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
4644    where
4645        C: ReadViewWith,
4646        F: FnOnce(&T, &AppContext) -> S,
4647    {
4648        let mut read = Some(read);
4649        cx.read_view_with(self, &mut |view, cx| {
4650            let read = read.take().unwrap();
4651            read(view, cx)
4652        })
4653    }
4654
4655    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
4656    where
4657        C: UpdateView,
4658        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
4659    {
4660        let mut update = Some(update);
4661        cx.update_view(self, &mut |view, cx| {
4662            let update = update.take().unwrap();
4663            update(view, cx)
4664        })
4665    }
4666
4667    pub fn defer<C, F>(&self, cx: &mut C, update: F)
4668    where
4669        C: AsMut<MutableAppContext>,
4670        F: 'static + FnOnce(&mut T, &mut ViewContext<T>),
4671    {
4672        let this = self.clone();
4673        cx.as_mut().defer(move |cx| {
4674            this.update(cx, |view, cx| update(view, cx));
4675        });
4676    }
4677
4678    pub fn is_focused(&self, cx: &AppContext) -> bool {
4679        cx.focused_view_id(self.window_id)
4680            .map_or(false, |focused_id| focused_id == self.view_id)
4681    }
4682
4683    #[cfg(any(test, feature = "test-support"))]
4684    pub fn next_notification(&self, cx: &TestAppContext) -> impl Future<Output = ()> {
4685        use postage::prelude::{Sink as _, Stream as _};
4686
4687        let (mut tx, mut rx) = postage::mpsc::channel(1);
4688        let mut cx = cx.cx.borrow_mut();
4689        let subscription = cx.observe(self, move |_, _| {
4690            tx.try_send(()).ok();
4691        });
4692
4693        let duration = if std::env::var("CI").is_ok() {
4694            Duration::from_secs(5)
4695        } else {
4696            Duration::from_secs(1)
4697        };
4698
4699        async move {
4700            let notification = crate::util::timeout(duration, rx.recv())
4701                .await
4702                .expect("next notification timed out");
4703            drop(subscription);
4704            notification.expect("model dropped while test was waiting for its next notification")
4705        }
4706    }
4707
4708    #[cfg(any(test, feature = "test-support"))]
4709    pub fn condition(
4710        &self,
4711        cx: &TestAppContext,
4712        mut predicate: impl FnMut(&T, &AppContext) -> bool,
4713    ) -> impl Future<Output = ()> {
4714        use postage::prelude::{Sink as _, Stream as _};
4715
4716        let (tx, mut rx) = postage::mpsc::channel(1024);
4717        let timeout_duration = cx.condition_duration();
4718
4719        let mut cx = cx.cx.borrow_mut();
4720        let subscriptions = self.update(&mut *cx, |_, cx| {
4721            (
4722                cx.observe(self, {
4723                    let mut tx = tx.clone();
4724                    move |_, _, _| {
4725                        tx.blocking_send(()).ok();
4726                    }
4727                }),
4728                cx.subscribe(self, {
4729                    let mut tx = tx.clone();
4730                    move |_, _, _, _| {
4731                        tx.blocking_send(()).ok();
4732                    }
4733                }),
4734            )
4735        });
4736
4737        let cx = cx.weak_self.as_ref().unwrap().upgrade().unwrap();
4738        let handle = self.downgrade();
4739
4740        async move {
4741            crate::util::timeout(timeout_duration, async move {
4742                loop {
4743                    {
4744                        let cx = cx.borrow();
4745                        let cx = cx.as_ref();
4746                        if predicate(
4747                            handle
4748                                .upgrade(cx)
4749                                .expect("view dropped with pending condition")
4750                                .read(cx),
4751                            cx,
4752                        ) {
4753                            break;
4754                        }
4755                    }
4756
4757                    cx.borrow().foreground().start_waiting();
4758                    rx.recv()
4759                        .await
4760                        .expect("view dropped with pending condition");
4761                    cx.borrow().foreground().finish_waiting();
4762                }
4763            })
4764            .await
4765            .expect("condition timed out");
4766            drop(subscriptions);
4767        }
4768    }
4769}
4770
4771impl<T: View> Clone for ViewHandle<T> {
4772    fn clone(&self) -> Self {
4773        ViewHandle::new(self.window_id, self.view_id, &self.ref_counts)
4774    }
4775}
4776
4777impl<T> PartialEq for ViewHandle<T> {
4778    fn eq(&self, other: &Self) -> bool {
4779        self.window_id == other.window_id && self.view_id == other.view_id
4780    }
4781}
4782
4783impl<T> PartialEq<WeakViewHandle<T>> for ViewHandle<T> {
4784    fn eq(&self, other: &WeakViewHandle<T>) -> bool {
4785        self.window_id == other.window_id && self.view_id == other.view_id
4786    }
4787}
4788
4789impl<T> PartialEq<ViewHandle<T>> for WeakViewHandle<T> {
4790    fn eq(&self, other: &ViewHandle<T>) -> bool {
4791        self.window_id == other.window_id && self.view_id == other.view_id
4792    }
4793}
4794
4795impl<T> Eq for ViewHandle<T> {}
4796
4797impl<T> Hash for ViewHandle<T> {
4798    fn hash<H: Hasher>(&self, state: &mut H) {
4799        self.window_id.hash(state);
4800        self.view_id.hash(state);
4801    }
4802}
4803
4804impl<T> Debug for ViewHandle<T> {
4805    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4806        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
4807            .field("window_id", &self.window_id)
4808            .field("view_id", &self.view_id)
4809            .finish()
4810    }
4811}
4812
4813impl<T> Drop for ViewHandle<T> {
4814    fn drop(&mut self) {
4815        self.ref_counts
4816            .lock()
4817            .dec_view(self.window_id, self.view_id);
4818        #[cfg(any(test, feature = "test-support"))]
4819        self.ref_counts
4820            .lock()
4821            .leak_detector
4822            .lock()
4823            .handle_dropped(self.view_id, self.handle_id);
4824    }
4825}
4826
4827impl<T: View> Handle<T> for ViewHandle<T> {
4828    type Weak = WeakViewHandle<T>;
4829
4830    fn id(&self) -> usize {
4831        self.view_id
4832    }
4833
4834    fn location(&self) -> EntityLocation {
4835        EntityLocation::View(self.window_id, self.view_id)
4836    }
4837
4838    fn downgrade(&self) -> Self::Weak {
4839        self.downgrade()
4840    }
4841
4842    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
4843    where
4844        Self: Sized,
4845    {
4846        weak.upgrade(cx)
4847    }
4848}
4849
4850pub struct AnyViewHandle {
4851    window_id: usize,
4852    view_id: usize,
4853    view_type: TypeId,
4854    ref_counts: Arc<Mutex<RefCounts>>,
4855
4856    #[cfg(any(test, feature = "test-support"))]
4857    handle_id: usize,
4858}
4859
4860impl AnyViewHandle {
4861    fn new(
4862        window_id: usize,
4863        view_id: usize,
4864        view_type: TypeId,
4865        ref_counts: Arc<Mutex<RefCounts>>,
4866    ) -> Self {
4867        ref_counts.lock().inc_view(window_id, view_id);
4868
4869        #[cfg(any(test, feature = "test-support"))]
4870        let handle_id = ref_counts
4871            .lock()
4872            .leak_detector
4873            .lock()
4874            .handle_created(None, view_id);
4875
4876        Self {
4877            window_id,
4878            view_id,
4879            view_type,
4880            ref_counts,
4881            #[cfg(any(test, feature = "test-support"))]
4882            handle_id,
4883        }
4884    }
4885
4886    pub fn id(&self) -> usize {
4887        self.view_id
4888    }
4889
4890    pub fn is<T: 'static>(&self) -> bool {
4891        TypeId::of::<T>() == self.view_type
4892    }
4893
4894    pub fn is_focused(&self, cx: &AppContext) -> bool {
4895        cx.focused_view_id(self.window_id)
4896            .map_or(false, |focused_id| focused_id == self.view_id)
4897    }
4898
4899    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
4900        if self.is::<T>() {
4901            let result = Some(ViewHandle {
4902                window_id: self.window_id,
4903                view_id: self.view_id,
4904                ref_counts: self.ref_counts.clone(),
4905                view_type: PhantomData,
4906                #[cfg(any(test, feature = "test-support"))]
4907                handle_id: self.handle_id,
4908            });
4909            unsafe {
4910                Arc::decrement_strong_count(Arc::as_ptr(&self.ref_counts));
4911            }
4912            std::mem::forget(self);
4913            result
4914        } else {
4915            None
4916        }
4917    }
4918
4919    pub fn downgrade(&self) -> AnyWeakViewHandle {
4920        AnyWeakViewHandle {
4921            window_id: self.window_id,
4922            view_id: self.view_id,
4923            view_type: self.view_type,
4924        }
4925    }
4926
4927    pub fn view_type(&self) -> TypeId {
4928        self.view_type
4929    }
4930
4931    pub fn debug_json(&self, cx: &AppContext) -> serde_json::Value {
4932        cx.views
4933            .get(&(self.window_id, self.view_id))
4934            .map_or_else(|| serde_json::Value::Null, |view| view.debug_json(cx))
4935    }
4936}
4937
4938impl Clone for AnyViewHandle {
4939    fn clone(&self) -> Self {
4940        Self::new(
4941            self.window_id,
4942            self.view_id,
4943            self.view_type,
4944            self.ref_counts.clone(),
4945        )
4946    }
4947}
4948
4949impl From<&AnyViewHandle> for AnyViewHandle {
4950    fn from(handle: &AnyViewHandle) -> Self {
4951        handle.clone()
4952    }
4953}
4954
4955impl<T: View> From<&ViewHandle<T>> for AnyViewHandle {
4956    fn from(handle: &ViewHandle<T>) -> Self {
4957        Self::new(
4958            handle.window_id,
4959            handle.view_id,
4960            TypeId::of::<T>(),
4961            handle.ref_counts.clone(),
4962        )
4963    }
4964}
4965
4966impl<T: View> From<ViewHandle<T>> for AnyViewHandle {
4967    fn from(handle: ViewHandle<T>) -> Self {
4968        let any_handle = AnyViewHandle {
4969            window_id: handle.window_id,
4970            view_id: handle.view_id,
4971            view_type: TypeId::of::<T>(),
4972            ref_counts: handle.ref_counts.clone(),
4973            #[cfg(any(test, feature = "test-support"))]
4974            handle_id: handle.handle_id,
4975        };
4976
4977        unsafe {
4978            Arc::decrement_strong_count(Arc::as_ptr(&handle.ref_counts));
4979        }
4980        std::mem::forget(handle);
4981        any_handle
4982    }
4983}
4984
4985impl Drop for AnyViewHandle {
4986    fn drop(&mut self) {
4987        self.ref_counts
4988            .lock()
4989            .dec_view(self.window_id, self.view_id);
4990        #[cfg(any(test, feature = "test-support"))]
4991        self.ref_counts
4992            .lock()
4993            .leak_detector
4994            .lock()
4995            .handle_dropped(self.view_id, self.handle_id);
4996    }
4997}
4998
4999pub struct AnyModelHandle {
5000    model_id: usize,
5001    model_type: TypeId,
5002    ref_counts: Arc<Mutex<RefCounts>>,
5003
5004    #[cfg(any(test, feature = "test-support"))]
5005    handle_id: usize,
5006}
5007
5008impl AnyModelHandle {
5009    fn new(model_id: usize, model_type: TypeId, ref_counts: Arc<Mutex<RefCounts>>) -> Self {
5010        ref_counts.lock().inc_model(model_id);
5011
5012        #[cfg(any(test, feature = "test-support"))]
5013        let handle_id = ref_counts
5014            .lock()
5015            .leak_detector
5016            .lock()
5017            .handle_created(None, model_id);
5018
5019        Self {
5020            model_id,
5021            model_type,
5022            ref_counts,
5023
5024            #[cfg(any(test, feature = "test-support"))]
5025            handle_id,
5026        }
5027    }
5028
5029    pub fn downcast<T: Entity>(self) -> Option<ModelHandle<T>> {
5030        if self.is::<T>() {
5031            let result = Some(ModelHandle {
5032                model_id: self.model_id,
5033                model_type: PhantomData,
5034                ref_counts: self.ref_counts.clone(),
5035
5036                #[cfg(any(test, feature = "test-support"))]
5037                handle_id: self.handle_id,
5038            });
5039            unsafe {
5040                Arc::decrement_strong_count(Arc::as_ptr(&self.ref_counts));
5041            }
5042            std::mem::forget(self);
5043            result
5044        } else {
5045            None
5046        }
5047    }
5048
5049    pub fn downgrade(&self) -> AnyWeakModelHandle {
5050        AnyWeakModelHandle {
5051            model_id: self.model_id,
5052            model_type: self.model_type,
5053        }
5054    }
5055
5056    pub fn is<T: Entity>(&self) -> bool {
5057        self.model_type == TypeId::of::<T>()
5058    }
5059
5060    pub fn model_type(&self) -> TypeId {
5061        self.model_type
5062    }
5063}
5064
5065impl<T: Entity> From<ModelHandle<T>> for AnyModelHandle {
5066    fn from(handle: ModelHandle<T>) -> Self {
5067        Self::new(
5068            handle.model_id,
5069            TypeId::of::<T>(),
5070            handle.ref_counts.clone(),
5071        )
5072    }
5073}
5074
5075impl Clone for AnyModelHandle {
5076    fn clone(&self) -> Self {
5077        Self::new(self.model_id, self.model_type, self.ref_counts.clone())
5078    }
5079}
5080
5081impl Drop for AnyModelHandle {
5082    fn drop(&mut self) {
5083        let mut ref_counts = self.ref_counts.lock();
5084        ref_counts.dec_model(self.model_id);
5085
5086        #[cfg(any(test, feature = "test-support"))]
5087        ref_counts
5088            .leak_detector
5089            .lock()
5090            .handle_dropped(self.model_id, self.handle_id);
5091    }
5092}
5093
5094#[derive(Hash, PartialEq, Eq, Debug)]
5095pub struct AnyWeakModelHandle {
5096    model_id: usize,
5097    model_type: TypeId,
5098}
5099
5100impl AnyWeakModelHandle {
5101    pub fn upgrade(&self, cx: &impl UpgradeModelHandle) -> Option<AnyModelHandle> {
5102        cx.upgrade_any_model_handle(self)
5103    }
5104    pub fn model_type(&self) -> TypeId {
5105        self.model_type
5106    }
5107
5108    fn is<T: 'static>(&self) -> bool {
5109        TypeId::of::<T>() == self.model_type
5110    }
5111
5112    pub fn downcast<T: Entity>(&self) -> Option<WeakModelHandle<T>> {
5113        if self.is::<T>() {
5114            let result = Some(WeakModelHandle {
5115                model_id: self.model_id,
5116                model_type: PhantomData,
5117            });
5118
5119            result
5120        } else {
5121            None
5122        }
5123    }
5124}
5125
5126impl<T: Entity> From<WeakModelHandle<T>> for AnyWeakModelHandle {
5127    fn from(handle: WeakModelHandle<T>) -> Self {
5128        AnyWeakModelHandle {
5129            model_id: handle.model_id,
5130            model_type: TypeId::of::<T>(),
5131        }
5132    }
5133}
5134
5135#[derive(Debug)]
5136pub struct WeakViewHandle<T> {
5137    window_id: usize,
5138    view_id: usize,
5139    view_type: PhantomData<T>,
5140}
5141
5142impl<T> WeakHandle for WeakViewHandle<T> {
5143    fn id(&self) -> usize {
5144        self.view_id
5145    }
5146}
5147
5148impl<T: View> WeakViewHandle<T> {
5149    fn new(window_id: usize, view_id: usize) -> Self {
5150        Self {
5151            window_id,
5152            view_id,
5153            view_type: PhantomData,
5154        }
5155    }
5156
5157    pub fn id(&self) -> usize {
5158        self.view_id
5159    }
5160
5161    pub fn window_id(&self) -> usize {
5162        self.window_id
5163    }
5164
5165    pub fn upgrade(&self, cx: &impl UpgradeViewHandle) -> Option<ViewHandle<T>> {
5166        cx.upgrade_view_handle(self)
5167    }
5168}
5169
5170impl<T> Clone for WeakViewHandle<T> {
5171    fn clone(&self) -> Self {
5172        Self {
5173            window_id: self.window_id,
5174            view_id: self.view_id,
5175            view_type: PhantomData,
5176        }
5177    }
5178}
5179
5180impl<T> PartialEq for WeakViewHandle<T> {
5181    fn eq(&self, other: &Self) -> bool {
5182        self.window_id == other.window_id && self.view_id == other.view_id
5183    }
5184}
5185
5186impl<T> Eq for WeakViewHandle<T> {}
5187
5188impl<T> Hash for WeakViewHandle<T> {
5189    fn hash<H: Hasher>(&self, state: &mut H) {
5190        self.window_id.hash(state);
5191        self.view_id.hash(state);
5192    }
5193}
5194
5195pub struct AnyWeakViewHandle {
5196    window_id: usize,
5197    view_id: usize,
5198    view_type: TypeId,
5199}
5200
5201impl AnyWeakViewHandle {
5202    pub fn upgrade(&self, cx: &impl UpgradeViewHandle) -> Option<AnyViewHandle> {
5203        cx.upgrade_any_view_handle(self)
5204    }
5205}
5206
5207impl<T: View> From<WeakViewHandle<T>> for AnyWeakViewHandle {
5208    fn from(handle: WeakViewHandle<T>) -> Self {
5209        AnyWeakViewHandle {
5210            window_id: handle.window_id,
5211            view_id: handle.view_id,
5212            view_type: TypeId::of::<T>(),
5213        }
5214    }
5215}
5216
5217#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
5218pub struct ElementStateId {
5219    view_id: usize,
5220    element_id: usize,
5221    tag: TypeId,
5222}
5223
5224pub struct ElementStateHandle<T> {
5225    value_type: PhantomData<T>,
5226    id: ElementStateId,
5227    ref_counts: Weak<Mutex<RefCounts>>,
5228}
5229
5230impl<T: 'static> ElementStateHandle<T> {
5231    fn new(id: ElementStateId, frame_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
5232        ref_counts.lock().inc_element_state(id, frame_id);
5233        Self {
5234            value_type: PhantomData,
5235            id,
5236            ref_counts: Arc::downgrade(ref_counts),
5237        }
5238    }
5239
5240    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
5241        cx.element_states
5242            .get(&self.id)
5243            .unwrap()
5244            .downcast_ref()
5245            .unwrap()
5246    }
5247
5248    pub fn update<C, R>(&self, cx: &mut C, f: impl FnOnce(&mut T, &mut C) -> R) -> R
5249    where
5250        C: DerefMut<Target = MutableAppContext>,
5251    {
5252        let mut element_state = cx.deref_mut().cx.element_states.remove(&self.id).unwrap();
5253        let result = f(element_state.downcast_mut().unwrap(), cx);
5254        cx.deref_mut()
5255            .cx
5256            .element_states
5257            .insert(self.id, element_state);
5258        result
5259    }
5260}
5261
5262impl<T> Drop for ElementStateHandle<T> {
5263    fn drop(&mut self) {
5264        if let Some(ref_counts) = self.ref_counts.upgrade() {
5265            ref_counts.lock().dec_element_state(self.id);
5266        }
5267    }
5268}
5269
5270#[must_use]
5271pub enum Subscription {
5272    Subscription {
5273        id: usize,
5274        entity_id: usize,
5275        subscriptions: Option<Weak<Mapping<usize, SubscriptionCallback>>>,
5276    },
5277    GlobalSubscription {
5278        id: usize,
5279        type_id: TypeId,
5280        subscriptions: Option<Weak<Mapping<TypeId, GlobalSubscriptionCallback>>>,
5281    },
5282    Observation {
5283        id: usize,
5284        entity_id: usize,
5285        observations: Option<Weak<Mapping<usize, ObservationCallback>>>,
5286    },
5287    GlobalObservation {
5288        id: usize,
5289        type_id: TypeId,
5290        observations: Option<Weak<Mapping<TypeId, GlobalObservationCallback>>>,
5291    },
5292    FocusObservation {
5293        id: usize,
5294        view_id: usize,
5295        observations: Option<Weak<Mapping<usize, FocusObservationCallback>>>,
5296    },
5297    WindowActivationObservation {
5298        id: usize,
5299        window_id: usize,
5300        observations: Option<Weak<Mapping<usize, WindowActivationCallback>>>,
5301    },
5302    WindowFullscreenObservation {
5303        id: usize,
5304        window_id: usize,
5305        observations: Option<Weak<Mapping<usize, WindowFullscreenCallback>>>,
5306    },
5307
5308    ReleaseObservation {
5309        id: usize,
5310        entity_id: usize,
5311        #[allow(clippy::type_complexity)]
5312        observations:
5313            Option<Weak<Mutex<HashMap<usize, BTreeMap<usize, ReleaseObservationCallback>>>>>,
5314    },
5315    ActionObservation {
5316        id: usize,
5317        observations: Option<Weak<Mutex<BTreeMap<usize, ActionObservationCallback>>>>,
5318    },
5319}
5320
5321impl Subscription {
5322    pub fn detach(&mut self) {
5323        match self {
5324            Subscription::Subscription { subscriptions, .. } => {
5325                subscriptions.take();
5326            }
5327            Subscription::GlobalSubscription { subscriptions, .. } => {
5328                subscriptions.take();
5329            }
5330            Subscription::Observation { observations, .. } => {
5331                observations.take();
5332            }
5333            Subscription::GlobalObservation { observations, .. } => {
5334                observations.take();
5335            }
5336            Subscription::ReleaseObservation { observations, .. } => {
5337                observations.take();
5338            }
5339            Subscription::FocusObservation { observations, .. } => {
5340                observations.take();
5341            }
5342            Subscription::ActionObservation { observations, .. } => {
5343                observations.take();
5344            }
5345            Subscription::WindowActivationObservation { observations, .. } => {
5346                observations.take();
5347            }
5348            Subscription::WindowFullscreenObservation { observations, .. } => {
5349                observations.take();
5350            }
5351        }
5352    }
5353}
5354
5355impl Drop for Subscription {
5356    fn drop(&mut self) {
5357        match self {
5358            Subscription::Subscription {
5359                id,
5360                entity_id,
5361                subscriptions,
5362            } => {
5363                if let Some(subscriptions) = subscriptions.as_ref().and_then(Weak::upgrade) {
5364                    match subscriptions
5365                        .lock()
5366                        .entry(*entity_id)
5367                        .or_default()
5368                        .entry(*id)
5369                    {
5370                        btree_map::Entry::Vacant(entry) => {
5371                            entry.insert(None);
5372                        }
5373                        btree_map::Entry::Occupied(entry) => {
5374                            entry.remove();
5375                        }
5376                    }
5377                }
5378            }
5379            Subscription::GlobalSubscription {
5380                id,
5381                type_id,
5382                subscriptions,
5383            } => {
5384                if let Some(subscriptions) = subscriptions.as_ref().and_then(Weak::upgrade) {
5385                    match subscriptions.lock().entry(*type_id).or_default().entry(*id) {
5386                        btree_map::Entry::Vacant(entry) => {
5387                            entry.insert(None);
5388                        }
5389                        btree_map::Entry::Occupied(entry) => {
5390                            entry.remove();
5391                        }
5392                    }
5393                }
5394            }
5395            Subscription::Observation {
5396                id,
5397                entity_id,
5398                observations,
5399            } => {
5400                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
5401                    match observations
5402                        .lock()
5403                        .entry(*entity_id)
5404                        .or_default()
5405                        .entry(*id)
5406                    {
5407                        btree_map::Entry::Vacant(entry) => {
5408                            entry.insert(None);
5409                        }
5410                        btree_map::Entry::Occupied(entry) => {
5411                            entry.remove();
5412                        }
5413                    }
5414                }
5415            }
5416            Subscription::GlobalObservation {
5417                id,
5418                type_id,
5419                observations,
5420            } => {
5421                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
5422                    match observations.lock().entry(*type_id).or_default().entry(*id) {
5423                        collections::btree_map::Entry::Vacant(entry) => {
5424                            entry.insert(None);
5425                        }
5426                        collections::btree_map::Entry::Occupied(entry) => {
5427                            entry.remove();
5428                        }
5429                    }
5430                }
5431            }
5432            Subscription::ReleaseObservation {
5433                id,
5434                entity_id,
5435                observations,
5436            } => {
5437                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
5438                    if let Some(observations) = observations.lock().get_mut(entity_id) {
5439                        observations.remove(id);
5440                    }
5441                }
5442            }
5443            Subscription::FocusObservation {
5444                id,
5445                view_id,
5446                observations,
5447            } => {
5448                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
5449                    match observations.lock().entry(*view_id).or_default().entry(*id) {
5450                        btree_map::Entry::Vacant(entry) => {
5451                            entry.insert(None);
5452                        }
5453                        btree_map::Entry::Occupied(entry) => {
5454                            entry.remove();
5455                        }
5456                    }
5457                }
5458            }
5459            Subscription::ActionObservation { id, observations } => {
5460                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
5461                    observations.lock().remove(id);
5462                }
5463            }
5464            Subscription::WindowActivationObservation {
5465                id,
5466                window_id,
5467                observations,
5468            } => {
5469                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
5470                    match observations
5471                        .lock()
5472                        .entry(*window_id)
5473                        .or_default()
5474                        .entry(*id)
5475                    {
5476                        btree_map::Entry::Vacant(entry) => {
5477                            entry.insert(None);
5478                        }
5479                        btree_map::Entry::Occupied(entry) => {
5480                            entry.remove();
5481                        }
5482                    }
5483                }
5484            }
5485            Subscription::WindowFullscreenObservation {
5486                id,
5487                window_id,
5488                observations,
5489            } => {
5490                if let Some(observations) = observations.as_ref().and_then(Weak::upgrade) {
5491                    match observations
5492                        .lock()
5493                        .entry(*window_id)
5494                        .or_default()
5495                        .entry(*id)
5496                    {
5497                        btree_map::Entry::Vacant(entry) => {
5498                            entry.insert(None);
5499                        }
5500                        btree_map::Entry::Occupied(entry) => {
5501                            entry.remove();
5502                        }
5503                    }
5504                }
5505            }
5506        }
5507    }
5508}
5509
5510lazy_static! {
5511    static ref LEAK_BACKTRACE: bool =
5512        std::env::var("LEAK_BACKTRACE").map_or(false, |b| !b.is_empty());
5513}
5514
5515#[cfg(any(test, feature = "test-support"))]
5516#[derive(Default)]
5517pub struct LeakDetector {
5518    next_handle_id: usize,
5519    #[allow(clippy::type_complexity)]
5520    handle_backtraces: HashMap<
5521        usize,
5522        (
5523            Option<&'static str>,
5524            HashMap<usize, Option<backtrace::Backtrace>>,
5525        ),
5526    >,
5527}
5528
5529#[cfg(any(test, feature = "test-support"))]
5530impl LeakDetector {
5531    fn handle_created(&mut self, type_name: Option<&'static str>, entity_id: usize) -> usize {
5532        let handle_id = post_inc(&mut self.next_handle_id);
5533        let entry = self.handle_backtraces.entry(entity_id).or_default();
5534        let backtrace = if *LEAK_BACKTRACE {
5535            Some(backtrace::Backtrace::new_unresolved())
5536        } else {
5537            None
5538        };
5539        if let Some(type_name) = type_name {
5540            entry.0.get_or_insert(type_name);
5541        }
5542        entry.1.insert(handle_id, backtrace);
5543        handle_id
5544    }
5545
5546    fn handle_dropped(&mut self, entity_id: usize, handle_id: usize) {
5547        if let Some((_, backtraces)) = self.handle_backtraces.get_mut(&entity_id) {
5548            assert!(backtraces.remove(&handle_id).is_some());
5549            if backtraces.is_empty() {
5550                self.handle_backtraces.remove(&entity_id);
5551            }
5552        }
5553    }
5554
5555    pub fn assert_dropped(&mut self, entity_id: usize) {
5556        if let Some((type_name, backtraces)) = self.handle_backtraces.get_mut(&entity_id) {
5557            for trace in backtraces.values_mut().flatten() {
5558                trace.resolve();
5559                eprintln!("{:?}", crate::util::CwdBacktrace(trace));
5560            }
5561
5562            let hint = if *LEAK_BACKTRACE {
5563                ""
5564            } else {
5565                " – set LEAK_BACKTRACE=1 for more information"
5566            };
5567
5568            panic!(
5569                "{} handles to {} {} still exist{}",
5570                backtraces.len(),
5571                type_name.unwrap_or("entity"),
5572                entity_id,
5573                hint
5574            );
5575        }
5576    }
5577
5578    pub fn detect(&mut self) {
5579        let mut found_leaks = false;
5580        for (id, (type_name, backtraces)) in self.handle_backtraces.iter_mut() {
5581            eprintln!(
5582                "leaked {} handles to {} {}",
5583                backtraces.len(),
5584                type_name.unwrap_or("entity"),
5585                id
5586            );
5587            for trace in backtraces.values_mut().flatten() {
5588                trace.resolve();
5589                eprintln!("{:?}", crate::util::CwdBacktrace(trace));
5590            }
5591            found_leaks = true;
5592        }
5593
5594        let hint = if *LEAK_BACKTRACE {
5595            ""
5596        } else {
5597            " – set LEAK_BACKTRACE=1 for more information"
5598        };
5599        assert!(!found_leaks, "detected leaked handles{}", hint);
5600    }
5601}
5602
5603#[derive(Default)]
5604struct RefCounts {
5605    entity_counts: HashMap<usize, usize>,
5606    element_state_counts: HashMap<ElementStateId, ElementStateRefCount>,
5607    dropped_models: HashSet<usize>,
5608    dropped_views: HashSet<(usize, usize)>,
5609    dropped_element_states: HashSet<ElementStateId>,
5610
5611    #[cfg(any(test, feature = "test-support"))]
5612    leak_detector: Arc<Mutex<LeakDetector>>,
5613}
5614
5615struct ElementStateRefCount {
5616    ref_count: usize,
5617    frame_id: usize,
5618}
5619
5620impl RefCounts {
5621    fn inc_model(&mut self, model_id: usize) {
5622        match self.entity_counts.entry(model_id) {
5623            Entry::Occupied(mut entry) => {
5624                *entry.get_mut() += 1;
5625            }
5626            Entry::Vacant(entry) => {
5627                entry.insert(1);
5628                self.dropped_models.remove(&model_id);
5629            }
5630        }
5631    }
5632
5633    fn inc_view(&mut self, window_id: usize, view_id: usize) {
5634        match self.entity_counts.entry(view_id) {
5635            Entry::Occupied(mut entry) => *entry.get_mut() += 1,
5636            Entry::Vacant(entry) => {
5637                entry.insert(1);
5638                self.dropped_views.remove(&(window_id, view_id));
5639            }
5640        }
5641    }
5642
5643    fn inc_element_state(&mut self, id: ElementStateId, frame_id: usize) {
5644        match self.element_state_counts.entry(id) {
5645            Entry::Occupied(mut entry) => {
5646                let entry = entry.get_mut();
5647                if entry.frame_id == frame_id || entry.ref_count >= 2 {
5648                    panic!("used the same element state more than once in the same frame");
5649                }
5650                entry.ref_count += 1;
5651                entry.frame_id = frame_id;
5652            }
5653            Entry::Vacant(entry) => {
5654                entry.insert(ElementStateRefCount {
5655                    ref_count: 1,
5656                    frame_id,
5657                });
5658                self.dropped_element_states.remove(&id);
5659            }
5660        }
5661    }
5662
5663    fn dec_model(&mut self, model_id: usize) {
5664        let count = self.entity_counts.get_mut(&model_id).unwrap();
5665        *count -= 1;
5666        if *count == 0 {
5667            self.entity_counts.remove(&model_id);
5668            self.dropped_models.insert(model_id);
5669        }
5670    }
5671
5672    fn dec_view(&mut self, window_id: usize, view_id: usize) {
5673        let count = self.entity_counts.get_mut(&view_id).unwrap();
5674        *count -= 1;
5675        if *count == 0 {
5676            self.entity_counts.remove(&view_id);
5677            self.dropped_views.insert((window_id, view_id));
5678        }
5679    }
5680
5681    fn dec_element_state(&mut self, id: ElementStateId) {
5682        let entry = self.element_state_counts.get_mut(&id).unwrap();
5683        entry.ref_count -= 1;
5684        if entry.ref_count == 0 {
5685            self.element_state_counts.remove(&id);
5686            self.dropped_element_states.insert(id);
5687        }
5688    }
5689
5690    fn is_entity_alive(&self, entity_id: usize) -> bool {
5691        self.entity_counts.contains_key(&entity_id)
5692    }
5693
5694    fn take_dropped(
5695        &mut self,
5696    ) -> (
5697        HashSet<usize>,
5698        HashSet<(usize, usize)>,
5699        HashSet<ElementStateId>,
5700    ) {
5701        (
5702            std::mem::take(&mut self.dropped_models),
5703            std::mem::take(&mut self.dropped_views),
5704            std::mem::take(&mut self.dropped_element_states),
5705        )
5706    }
5707}
5708
5709#[cfg(test)]
5710mod tests {
5711    use super::*;
5712    use crate::{actions, elements::*, impl_actions, MouseButton, MouseButtonEvent};
5713    use serde::Deserialize;
5714    use smol::future::poll_once;
5715    use std::{
5716        cell::Cell,
5717        sync::atomic::{AtomicBool, AtomicUsize, Ordering::SeqCst},
5718    };
5719
5720    #[crate::test(self)]
5721    fn test_model_handles(cx: &mut MutableAppContext) {
5722        struct Model {
5723            other: Option<ModelHandle<Model>>,
5724            events: Vec<String>,
5725        }
5726
5727        impl Entity for Model {
5728            type Event = usize;
5729        }
5730
5731        impl Model {
5732            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
5733                if let Some(other) = other.as_ref() {
5734                    cx.observe(other, |me, _, _| {
5735                        me.events.push("notified".into());
5736                    })
5737                    .detach();
5738                    cx.subscribe(other, |me, _, event, _| {
5739                        me.events.push(format!("observed event {}", event));
5740                    })
5741                    .detach();
5742                }
5743
5744                Self {
5745                    other,
5746                    events: Vec::new(),
5747                }
5748            }
5749        }
5750
5751        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
5752        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
5753        assert_eq!(cx.cx.models.len(), 2);
5754
5755        handle_1.update(cx, |model, cx| {
5756            model.events.push("updated".into());
5757            cx.emit(1);
5758            cx.notify();
5759            cx.emit(2);
5760        });
5761        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
5762        assert_eq!(
5763            handle_2.read(cx).events,
5764            vec![
5765                "observed event 1".to_string(),
5766                "notified".to_string(),
5767                "observed event 2".to_string(),
5768            ]
5769        );
5770
5771        handle_2.update(cx, |model, _| {
5772            drop(handle_1);
5773            model.other.take();
5774        });
5775
5776        assert_eq!(cx.cx.models.len(), 1);
5777        assert!(cx.subscriptions.is_empty());
5778        assert!(cx.observations.is_empty());
5779    }
5780
5781    #[crate::test(self)]
5782    fn test_model_events(cx: &mut MutableAppContext) {
5783        #[derive(Default)]
5784        struct Model {
5785            events: Vec<usize>,
5786        }
5787
5788        impl Entity for Model {
5789            type Event = usize;
5790        }
5791
5792        let handle_1 = cx.add_model(|_| Model::default());
5793        let handle_2 = cx.add_model(|_| Model::default());
5794
5795        handle_1.update(cx, |_, cx| {
5796            cx.subscribe(&handle_2, move |model: &mut Model, emitter, event, cx| {
5797                model.events.push(*event);
5798
5799                cx.subscribe(&emitter, |model, _, event, _| {
5800                    model.events.push(*event * 2);
5801                })
5802                .detach();
5803            })
5804            .detach();
5805        });
5806
5807        handle_2.update(cx, |_, c| c.emit(7));
5808        assert_eq!(handle_1.read(cx).events, vec![7]);
5809
5810        handle_2.update(cx, |_, c| c.emit(5));
5811        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
5812    }
5813
5814    #[crate::test(self)]
5815    fn test_model_emit_before_subscribe_in_same_update_cycle(cx: &mut MutableAppContext) {
5816        #[derive(Default)]
5817        struct Model;
5818
5819        impl Entity for Model {
5820            type Event = ();
5821        }
5822
5823        let events = Rc::new(RefCell::new(Vec::new()));
5824        cx.add_model(|cx| {
5825            drop(cx.subscribe(&cx.handle(), {
5826                let events = events.clone();
5827                move |_, _, _, _| events.borrow_mut().push("dropped before flush")
5828            }));
5829            cx.subscribe(&cx.handle(), {
5830                let events = events.clone();
5831                move |_, _, _, _| events.borrow_mut().push("before emit")
5832            })
5833            .detach();
5834            cx.emit(());
5835            cx.subscribe(&cx.handle(), {
5836                let events = events.clone();
5837                move |_, _, _, _| events.borrow_mut().push("after emit")
5838            })
5839            .detach();
5840            Model
5841        });
5842        assert_eq!(*events.borrow(), ["before emit"]);
5843    }
5844
5845    #[crate::test(self)]
5846    fn test_observe_and_notify_from_model(cx: &mut MutableAppContext) {
5847        #[derive(Default)]
5848        struct Model {
5849            count: usize,
5850            events: Vec<usize>,
5851        }
5852
5853        impl Entity for Model {
5854            type Event = ();
5855        }
5856
5857        let handle_1 = cx.add_model(|_| Model::default());
5858        let handle_2 = cx.add_model(|_| Model::default());
5859
5860        handle_1.update(cx, |_, c| {
5861            c.observe(&handle_2, move |model, observed, c| {
5862                model.events.push(observed.read(c).count);
5863                c.observe(&observed, |model, observed, c| {
5864                    model.events.push(observed.read(c).count * 2);
5865                })
5866                .detach();
5867            })
5868            .detach();
5869        });
5870
5871        handle_2.update(cx, |model, c| {
5872            model.count = 7;
5873            c.notify()
5874        });
5875        assert_eq!(handle_1.read(cx).events, vec![7]);
5876
5877        handle_2.update(cx, |model, c| {
5878            model.count = 5;
5879            c.notify()
5880        });
5881        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10])
5882    }
5883
5884    #[crate::test(self)]
5885    fn test_model_notify_before_observe_in_same_update_cycle(cx: &mut MutableAppContext) {
5886        #[derive(Default)]
5887        struct Model;
5888
5889        impl Entity for Model {
5890            type Event = ();
5891        }
5892
5893        let events = Rc::new(RefCell::new(Vec::new()));
5894        cx.add_model(|cx| {
5895            drop(cx.observe(&cx.handle(), {
5896                let events = events.clone();
5897                move |_, _, _| events.borrow_mut().push("dropped before flush")
5898            }));
5899            cx.observe(&cx.handle(), {
5900                let events = events.clone();
5901                move |_, _, _| events.borrow_mut().push("before notify")
5902            })
5903            .detach();
5904            cx.notify();
5905            cx.observe(&cx.handle(), {
5906                let events = events.clone();
5907                move |_, _, _| events.borrow_mut().push("after notify")
5908            })
5909            .detach();
5910            Model
5911        });
5912        assert_eq!(*events.borrow(), ["before notify"]);
5913    }
5914
5915    #[crate::test(self)]
5916    fn test_defer_and_after_window_update(cx: &mut MutableAppContext) {
5917        struct View {
5918            render_count: usize,
5919        }
5920
5921        impl Entity for View {
5922            type Event = usize;
5923        }
5924
5925        impl super::View for View {
5926            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
5927                post_inc(&mut self.render_count);
5928                Empty::new().boxed()
5929            }
5930
5931            fn ui_name() -> &'static str {
5932                "View"
5933            }
5934        }
5935
5936        let (_, view) = cx.add_window(Default::default(), |_| View { render_count: 0 });
5937        let called_defer = Rc::new(AtomicBool::new(false));
5938        let called_after_window_update = Rc::new(AtomicBool::new(false));
5939
5940        view.update(cx, |this, cx| {
5941            assert_eq!(this.render_count, 1);
5942            cx.defer({
5943                let called_defer = called_defer.clone();
5944                move |this, _| {
5945                    assert_eq!(this.render_count, 1);
5946                    called_defer.store(true, SeqCst);
5947                }
5948            });
5949            cx.after_window_update({
5950                let called_after_window_update = called_after_window_update.clone();
5951                move |this, cx| {
5952                    assert_eq!(this.render_count, 2);
5953                    called_after_window_update.store(true, SeqCst);
5954                    cx.notify();
5955                }
5956            });
5957            assert!(!called_defer.load(SeqCst));
5958            assert!(!called_after_window_update.load(SeqCst));
5959            cx.notify();
5960        });
5961
5962        assert!(called_defer.load(SeqCst));
5963        assert!(called_after_window_update.load(SeqCst));
5964        assert_eq!(view.read(cx).render_count, 3);
5965    }
5966
5967    #[crate::test(self)]
5968    fn test_view_handles(cx: &mut MutableAppContext) {
5969        struct View {
5970            other: Option<ViewHandle<View>>,
5971            events: Vec<String>,
5972        }
5973
5974        impl Entity for View {
5975            type Event = usize;
5976        }
5977
5978        impl super::View for View {
5979            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
5980                Empty::new().boxed()
5981            }
5982
5983            fn ui_name() -> &'static str {
5984                "View"
5985            }
5986        }
5987
5988        impl View {
5989            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
5990                if let Some(other) = other.as_ref() {
5991                    cx.subscribe(other, |me, _, event, _| {
5992                        me.events.push(format!("observed event {}", event));
5993                    })
5994                    .detach();
5995                }
5996                Self {
5997                    other,
5998                    events: Vec::new(),
5999                }
6000            }
6001        }
6002
6003        let (_, root_view) = cx.add_window(Default::default(), |cx| View::new(None, cx));
6004        let handle_1 = cx.add_view(&root_view, |cx| View::new(None, cx));
6005        let handle_2 = cx.add_view(&root_view, |cx| View::new(Some(handle_1.clone()), cx));
6006        assert_eq!(cx.cx.views.len(), 3);
6007
6008        handle_1.update(cx, |view, cx| {
6009            view.events.push("updated".into());
6010            cx.emit(1);
6011            cx.emit(2);
6012        });
6013        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
6014        assert_eq!(
6015            handle_2.read(cx).events,
6016            vec![
6017                "observed event 1".to_string(),
6018                "observed event 2".to_string(),
6019            ]
6020        );
6021
6022        handle_2.update(cx, |view, _| {
6023            drop(handle_1);
6024            view.other.take();
6025        });
6026
6027        assert_eq!(cx.cx.views.len(), 2);
6028        assert!(cx.subscriptions.is_empty());
6029        assert!(cx.observations.is_empty());
6030    }
6031
6032    #[crate::test(self)]
6033    fn test_add_window(cx: &mut MutableAppContext) {
6034        struct View {
6035            mouse_down_count: Arc<AtomicUsize>,
6036        }
6037
6038        impl Entity for View {
6039            type Event = ();
6040        }
6041
6042        impl super::View for View {
6043            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6044                let mouse_down_count = self.mouse_down_count.clone();
6045                EventHandler::new(Empty::new().boxed())
6046                    .on_mouse_down(move |_| {
6047                        mouse_down_count.fetch_add(1, SeqCst);
6048                        true
6049                    })
6050                    .boxed()
6051            }
6052
6053            fn ui_name() -> &'static str {
6054                "View"
6055            }
6056        }
6057
6058        let mouse_down_count = Arc::new(AtomicUsize::new(0));
6059        let (window_id, _) = cx.add_window(Default::default(), |_| View {
6060            mouse_down_count: mouse_down_count.clone(),
6061        });
6062        let presenter = cx.presenters_and_platform_windows[&window_id].0.clone();
6063        // Ensure window's root element is in a valid lifecycle state.
6064        presenter.borrow_mut().dispatch_event(
6065            Event::MouseDown(MouseButtonEvent {
6066                position: Default::default(),
6067                button: MouseButton::Left,
6068                ctrl: false,
6069                alt: false,
6070                shift: false,
6071                cmd: false,
6072                click_count: 1,
6073            }),
6074            false,
6075            cx,
6076        );
6077        assert_eq!(mouse_down_count.load(SeqCst), 1);
6078    }
6079
6080    #[crate::test(self)]
6081    fn test_entity_release_hooks(cx: &mut MutableAppContext) {
6082        struct Model {
6083            released: Rc<Cell<bool>>,
6084        }
6085
6086        struct View {
6087            released: Rc<Cell<bool>>,
6088        }
6089
6090        impl Entity for Model {
6091            type Event = ();
6092
6093            fn release(&mut self, _: &mut MutableAppContext) {
6094                self.released.set(true);
6095            }
6096        }
6097
6098        impl Entity for View {
6099            type Event = ();
6100
6101            fn release(&mut self, _: &mut MutableAppContext) {
6102                self.released.set(true);
6103            }
6104        }
6105
6106        impl super::View for View {
6107            fn ui_name() -> &'static str {
6108                "View"
6109            }
6110
6111            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6112                Empty::new().boxed()
6113            }
6114        }
6115
6116        let model_released = Rc::new(Cell::new(false));
6117        let model_release_observed = Rc::new(Cell::new(false));
6118        let view_released = Rc::new(Cell::new(false));
6119        let view_release_observed = Rc::new(Cell::new(false));
6120
6121        let model = cx.add_model(|_| Model {
6122            released: model_released.clone(),
6123        });
6124        let (window_id, view) = cx.add_window(Default::default(), |_| View {
6125            released: view_released.clone(),
6126        });
6127        assert!(!model_released.get());
6128        assert!(!view_released.get());
6129
6130        cx.observe_release(&model, {
6131            let model_release_observed = model_release_observed.clone();
6132            move |_, _| model_release_observed.set(true)
6133        })
6134        .detach();
6135        cx.observe_release(&view, {
6136            let view_release_observed = view_release_observed.clone();
6137            move |_, _| view_release_observed.set(true)
6138        })
6139        .detach();
6140
6141        cx.update(move |_| {
6142            drop(model);
6143        });
6144        assert!(model_released.get());
6145        assert!(model_release_observed.get());
6146
6147        drop(view);
6148        cx.remove_window(window_id);
6149        assert!(view_released.get());
6150        assert!(view_release_observed.get());
6151    }
6152
6153    #[crate::test(self)]
6154    fn test_view_events(cx: &mut MutableAppContext) {
6155        #[derive(Default)]
6156        struct View {
6157            events: Vec<usize>,
6158        }
6159
6160        impl Entity for View {
6161            type Event = usize;
6162        }
6163
6164        impl super::View for View {
6165            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6166                Empty::new().boxed()
6167            }
6168
6169            fn ui_name() -> &'static str {
6170                "View"
6171            }
6172        }
6173
6174        struct Model;
6175
6176        impl Entity for Model {
6177            type Event = usize;
6178        }
6179
6180        let (_, handle_1) = cx.add_window(Default::default(), |_| View::default());
6181        let handle_2 = cx.add_view(&handle_1, |_| View::default());
6182        let handle_3 = cx.add_model(|_| Model);
6183
6184        handle_1.update(cx, |_, cx| {
6185            cx.subscribe(&handle_2, move |me, emitter, event, cx| {
6186                me.events.push(*event);
6187
6188                cx.subscribe(&emitter, |me, _, event, _| {
6189                    me.events.push(*event * 2);
6190                })
6191                .detach();
6192            })
6193            .detach();
6194
6195            cx.subscribe(&handle_3, |me, _, event, _| {
6196                me.events.push(*event);
6197            })
6198            .detach();
6199        });
6200
6201        handle_2.update(cx, |_, c| c.emit(7));
6202        assert_eq!(handle_1.read(cx).events, vec![7]);
6203
6204        handle_2.update(cx, |_, c| c.emit(5));
6205        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
6206
6207        handle_3.update(cx, |_, c| c.emit(9));
6208        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10, 9]);
6209    }
6210
6211    #[crate::test(self)]
6212    fn test_global_events(cx: &mut MutableAppContext) {
6213        #[derive(Clone, Debug, Eq, PartialEq)]
6214        struct GlobalEvent(u64);
6215
6216        let events = Rc::new(RefCell::new(Vec::new()));
6217        let first_subscription;
6218        let second_subscription;
6219
6220        {
6221            let events = events.clone();
6222            first_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
6223                events.borrow_mut().push(("First", e.clone()));
6224            });
6225        }
6226
6227        {
6228            let events = events.clone();
6229            second_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
6230                events.borrow_mut().push(("Second", e.clone()));
6231            });
6232        }
6233
6234        cx.update(|cx| {
6235            cx.emit_global(GlobalEvent(1));
6236            cx.emit_global(GlobalEvent(2));
6237        });
6238
6239        drop(first_subscription);
6240
6241        cx.update(|cx| {
6242            cx.emit_global(GlobalEvent(3));
6243        });
6244
6245        drop(second_subscription);
6246
6247        cx.update(|cx| {
6248            cx.emit_global(GlobalEvent(4));
6249        });
6250
6251        assert_eq!(
6252            &*events.borrow(),
6253            &[
6254                ("First", GlobalEvent(1)),
6255                ("Second", GlobalEvent(1)),
6256                ("First", GlobalEvent(2)),
6257                ("Second", GlobalEvent(2)),
6258                ("Second", GlobalEvent(3)),
6259            ]
6260        );
6261    }
6262
6263    #[crate::test(self)]
6264    fn test_global_events_emitted_before_subscription_in_same_update_cycle(
6265        cx: &mut MutableAppContext,
6266    ) {
6267        let events = Rc::new(RefCell::new(Vec::new()));
6268        cx.update(|cx| {
6269            {
6270                let events = events.clone();
6271                drop(cx.subscribe_global(move |_: &(), _| {
6272                    events.borrow_mut().push("dropped before emit");
6273                }));
6274            }
6275
6276            {
6277                let events = events.clone();
6278                cx.subscribe_global(move |_: &(), _| {
6279                    events.borrow_mut().push("before emit");
6280                })
6281                .detach();
6282            }
6283
6284            cx.emit_global(());
6285
6286            {
6287                let events = events.clone();
6288                cx.subscribe_global(move |_: &(), _| {
6289                    events.borrow_mut().push("after emit");
6290                })
6291                .detach();
6292            }
6293        });
6294
6295        assert_eq!(*events.borrow(), ["before emit"]);
6296    }
6297
6298    #[crate::test(self)]
6299    fn test_global_nested_events(cx: &mut MutableAppContext) {
6300        #[derive(Clone, Debug, Eq, PartialEq)]
6301        struct GlobalEvent(u64);
6302
6303        let events = Rc::new(RefCell::new(Vec::new()));
6304
6305        {
6306            let events = events.clone();
6307            cx.subscribe_global(move |e: &GlobalEvent, cx| {
6308                events.borrow_mut().push(("Outer", e.clone()));
6309
6310                if e.0 == 1 {
6311                    let events = events.clone();
6312                    cx.subscribe_global(move |e: &GlobalEvent, _| {
6313                        events.borrow_mut().push(("Inner", e.clone()));
6314                    })
6315                    .detach();
6316                }
6317            })
6318            .detach();
6319        }
6320
6321        cx.update(|cx| {
6322            cx.emit_global(GlobalEvent(1));
6323            cx.emit_global(GlobalEvent(2));
6324            cx.emit_global(GlobalEvent(3));
6325        });
6326        cx.update(|cx| {
6327            cx.emit_global(GlobalEvent(4));
6328        });
6329
6330        assert_eq!(
6331            &*events.borrow(),
6332            &[
6333                ("Outer", GlobalEvent(1)),
6334                ("Outer", GlobalEvent(2)),
6335                ("Outer", GlobalEvent(3)),
6336                ("Outer", GlobalEvent(4)),
6337                ("Inner", GlobalEvent(4)),
6338            ]
6339        );
6340    }
6341
6342    #[crate::test(self)]
6343    fn test_global(cx: &mut MutableAppContext) {
6344        type Global = usize;
6345
6346        let observation_count = Rc::new(RefCell::new(0));
6347        let subscription = cx.observe_global::<Global, _>({
6348            let observation_count = observation_count.clone();
6349            move |_| {
6350                *observation_count.borrow_mut() += 1;
6351            }
6352        });
6353
6354        assert!(!cx.has_global::<Global>());
6355        assert_eq!(cx.default_global::<Global>(), &0);
6356        assert_eq!(*observation_count.borrow(), 1);
6357        assert!(cx.has_global::<Global>());
6358        assert_eq!(
6359            cx.update_global::<Global, _, _>(|global, _| {
6360                *global = 1;
6361                "Update Result"
6362            }),
6363            "Update Result"
6364        );
6365        assert_eq!(*observation_count.borrow(), 2);
6366        assert_eq!(cx.global::<Global>(), &1);
6367
6368        drop(subscription);
6369        cx.update_global::<Global, _, _>(|global, _| {
6370            *global = 2;
6371        });
6372        assert_eq!(*observation_count.borrow(), 2);
6373
6374        type OtherGlobal = f32;
6375
6376        let observation_count = Rc::new(RefCell::new(0));
6377        cx.observe_global::<OtherGlobal, _>({
6378            let observation_count = observation_count.clone();
6379            move |_| {
6380                *observation_count.borrow_mut() += 1;
6381            }
6382        })
6383        .detach();
6384
6385        assert_eq!(
6386            cx.update_default_global::<OtherGlobal, _, _>(|global, _| {
6387                assert_eq!(global, &0.0);
6388                *global = 2.0;
6389                "Default update result"
6390            }),
6391            "Default update result"
6392        );
6393        assert_eq!(cx.global::<OtherGlobal>(), &2.0);
6394        assert_eq!(*observation_count.borrow(), 1);
6395    }
6396
6397    #[crate::test(self)]
6398    fn test_dropping_subscribers(cx: &mut MutableAppContext) {
6399        struct View;
6400
6401        impl Entity for View {
6402            type Event = ();
6403        }
6404
6405        impl super::View for View {
6406            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6407                Empty::new().boxed()
6408            }
6409
6410            fn ui_name() -> &'static str {
6411                "View"
6412            }
6413        }
6414
6415        struct Model;
6416
6417        impl Entity for Model {
6418            type Event = ();
6419        }
6420
6421        let (_, root_view) = cx.add_window(Default::default(), |_| View);
6422        let observing_view = cx.add_view(&root_view, |_| View);
6423        let emitting_view = cx.add_view(&root_view, |_| View);
6424        let observing_model = cx.add_model(|_| Model);
6425        let observed_model = cx.add_model(|_| Model);
6426
6427        observing_view.update(cx, |_, cx| {
6428            cx.subscribe(&emitting_view, |_, _, _, _| {}).detach();
6429            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
6430        });
6431        observing_model.update(cx, |_, cx| {
6432            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
6433        });
6434
6435        cx.update(|_| {
6436            drop(observing_view);
6437            drop(observing_model);
6438        });
6439
6440        emitting_view.update(cx, |_, cx| cx.emit(()));
6441        observed_model.update(cx, |_, cx| cx.emit(()));
6442    }
6443
6444    #[crate::test(self)]
6445    fn test_view_emit_before_subscribe_in_same_update_cycle(cx: &mut MutableAppContext) {
6446        #[derive(Default)]
6447        struct TestView;
6448
6449        impl Entity for TestView {
6450            type Event = ();
6451        }
6452
6453        impl View for TestView {
6454            fn ui_name() -> &'static str {
6455                "TestView"
6456            }
6457
6458            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6459                Empty::new().boxed()
6460            }
6461        }
6462
6463        let events = Rc::new(RefCell::new(Vec::new()));
6464        cx.add_window(Default::default(), |cx| {
6465            drop(cx.subscribe(&cx.handle(), {
6466                let events = events.clone();
6467                move |_, _, _, _| events.borrow_mut().push("dropped before flush")
6468            }));
6469            cx.subscribe(&cx.handle(), {
6470                let events = events.clone();
6471                move |_, _, _, _| events.borrow_mut().push("before emit")
6472            })
6473            .detach();
6474            cx.emit(());
6475            cx.subscribe(&cx.handle(), {
6476                let events = events.clone();
6477                move |_, _, _, _| events.borrow_mut().push("after emit")
6478            })
6479            .detach();
6480            TestView
6481        });
6482        assert_eq!(*events.borrow(), ["before emit"]);
6483    }
6484
6485    #[crate::test(self)]
6486    fn test_observe_and_notify_from_view(cx: &mut MutableAppContext) {
6487        #[derive(Default)]
6488        struct View {
6489            events: Vec<usize>,
6490        }
6491
6492        impl Entity for View {
6493            type Event = usize;
6494        }
6495
6496        impl super::View for View {
6497            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6498                Empty::new().boxed()
6499            }
6500
6501            fn ui_name() -> &'static str {
6502                "View"
6503            }
6504        }
6505
6506        #[derive(Default)]
6507        struct Model {
6508            count: usize,
6509        }
6510
6511        impl Entity for Model {
6512            type Event = ();
6513        }
6514
6515        let (_, view) = cx.add_window(Default::default(), |_| View::default());
6516        let model = cx.add_model(|_| Model::default());
6517
6518        view.update(cx, |_, c| {
6519            c.observe(&model, |me, observed, c| {
6520                me.events.push(observed.read(c).count)
6521            })
6522            .detach();
6523        });
6524
6525        model.update(cx, |model, c| {
6526            model.count = 11;
6527            c.notify();
6528        });
6529        assert_eq!(view.read(cx).events, vec![11]);
6530    }
6531
6532    #[crate::test(self)]
6533    fn test_view_notify_before_observe_in_same_update_cycle(cx: &mut MutableAppContext) {
6534        #[derive(Default)]
6535        struct TestView;
6536
6537        impl Entity for TestView {
6538            type Event = ();
6539        }
6540
6541        impl View for TestView {
6542            fn ui_name() -> &'static str {
6543                "TestView"
6544            }
6545
6546            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6547                Empty::new().boxed()
6548            }
6549        }
6550
6551        let events = Rc::new(RefCell::new(Vec::new()));
6552        cx.add_window(Default::default(), |cx| {
6553            drop(cx.observe(&cx.handle(), {
6554                let events = events.clone();
6555                move |_, _, _| events.borrow_mut().push("dropped before flush")
6556            }));
6557            cx.observe(&cx.handle(), {
6558                let events = events.clone();
6559                move |_, _, _| events.borrow_mut().push("before notify")
6560            })
6561            .detach();
6562            cx.notify();
6563            cx.observe(&cx.handle(), {
6564                let events = events.clone();
6565                move |_, _, _| events.borrow_mut().push("after notify")
6566            })
6567            .detach();
6568            TestView
6569        });
6570        assert_eq!(*events.borrow(), ["before notify"]);
6571    }
6572
6573    #[crate::test(self)]
6574    fn test_dropping_observers(cx: &mut MutableAppContext) {
6575        struct View;
6576
6577        impl Entity for View {
6578            type Event = ();
6579        }
6580
6581        impl super::View for View {
6582            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6583                Empty::new().boxed()
6584            }
6585
6586            fn ui_name() -> &'static str {
6587                "View"
6588            }
6589        }
6590
6591        struct Model;
6592
6593        impl Entity for Model {
6594            type Event = ();
6595        }
6596
6597        let (_, root_view) = cx.add_window(Default::default(), |_| View);
6598        let observing_view = cx.add_view(root_view, |_| View);
6599        let observing_model = cx.add_model(|_| Model);
6600        let observed_model = cx.add_model(|_| Model);
6601
6602        observing_view.update(cx, |_, cx| {
6603            cx.observe(&observed_model, |_, _, _| {}).detach();
6604        });
6605        observing_model.update(cx, |_, cx| {
6606            cx.observe(&observed_model, |_, _, _| {}).detach();
6607        });
6608
6609        cx.update(|_| {
6610            drop(observing_view);
6611            drop(observing_model);
6612        });
6613
6614        observed_model.update(cx, |_, cx| cx.notify());
6615    }
6616
6617    #[crate::test(self)]
6618    fn test_dropping_subscriptions_during_callback(cx: &mut MutableAppContext) {
6619        struct Model;
6620
6621        impl Entity for Model {
6622            type Event = u64;
6623        }
6624
6625        // Events
6626        let observing_model = cx.add_model(|_| Model);
6627        let observed_model = cx.add_model(|_| Model);
6628
6629        let events = Rc::new(RefCell::new(Vec::new()));
6630
6631        observing_model.update(cx, |_, cx| {
6632            let events = events.clone();
6633            let subscription = Rc::new(RefCell::new(None));
6634            *subscription.borrow_mut() = Some(cx.subscribe(&observed_model, {
6635                let subscription = subscription.clone();
6636                move |_, _, e, _| {
6637                    subscription.borrow_mut().take();
6638                    events.borrow_mut().push(*e);
6639                }
6640            }));
6641        });
6642
6643        observed_model.update(cx, |_, cx| {
6644            cx.emit(1);
6645            cx.emit(2);
6646        });
6647
6648        assert_eq!(*events.borrow(), [1]);
6649
6650        // Global Events
6651        #[derive(Clone, Debug, Eq, PartialEq)]
6652        struct GlobalEvent(u64);
6653
6654        let events = Rc::new(RefCell::new(Vec::new()));
6655
6656        {
6657            let events = events.clone();
6658            let subscription = Rc::new(RefCell::new(None));
6659            *subscription.borrow_mut() = Some(cx.subscribe_global({
6660                let subscription = subscription.clone();
6661                move |e: &GlobalEvent, _| {
6662                    subscription.borrow_mut().take();
6663                    events.borrow_mut().push(e.clone());
6664                }
6665            }));
6666        }
6667
6668        cx.update(|cx| {
6669            cx.emit_global(GlobalEvent(1));
6670            cx.emit_global(GlobalEvent(2));
6671        });
6672
6673        assert_eq!(*events.borrow(), [GlobalEvent(1)]);
6674
6675        // Model Observation
6676        let observing_model = cx.add_model(|_| Model);
6677        let observed_model = cx.add_model(|_| Model);
6678
6679        let observation_count = Rc::new(RefCell::new(0));
6680
6681        observing_model.update(cx, |_, cx| {
6682            let observation_count = observation_count.clone();
6683            let subscription = Rc::new(RefCell::new(None));
6684            *subscription.borrow_mut() = Some(cx.observe(&observed_model, {
6685                let subscription = subscription.clone();
6686                move |_, _, _| {
6687                    subscription.borrow_mut().take();
6688                    *observation_count.borrow_mut() += 1;
6689                }
6690            }));
6691        });
6692
6693        observed_model.update(cx, |_, cx| {
6694            cx.notify();
6695        });
6696
6697        observed_model.update(cx, |_, cx| {
6698            cx.notify();
6699        });
6700
6701        assert_eq!(*observation_count.borrow(), 1);
6702
6703        // View Observation
6704        struct View;
6705
6706        impl Entity for View {
6707            type Event = ();
6708        }
6709
6710        impl super::View for View {
6711            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6712                Empty::new().boxed()
6713            }
6714
6715            fn ui_name() -> &'static str {
6716                "View"
6717            }
6718        }
6719
6720        let (_, root_view) = cx.add_window(Default::default(), |_| View);
6721        let observing_view = cx.add_view(&root_view, |_| View);
6722        let observed_view = cx.add_view(&root_view, |_| View);
6723
6724        let observation_count = Rc::new(RefCell::new(0));
6725        observing_view.update(cx, |_, cx| {
6726            let observation_count = observation_count.clone();
6727            let subscription = Rc::new(RefCell::new(None));
6728            *subscription.borrow_mut() = Some(cx.observe(&observed_view, {
6729                let subscription = subscription.clone();
6730                move |_, _, _| {
6731                    subscription.borrow_mut().take();
6732                    *observation_count.borrow_mut() += 1;
6733                }
6734            }));
6735        });
6736
6737        observed_view.update(cx, |_, cx| {
6738            cx.notify();
6739        });
6740
6741        observed_view.update(cx, |_, cx| {
6742            cx.notify();
6743        });
6744
6745        assert_eq!(*observation_count.borrow(), 1);
6746
6747        // Global Observation
6748        let observation_count = Rc::new(RefCell::new(0));
6749        let subscription = Rc::new(RefCell::new(None));
6750        *subscription.borrow_mut() = Some(cx.observe_global::<(), _>({
6751            let observation_count = observation_count.clone();
6752            let subscription = subscription.clone();
6753            move |_| {
6754                subscription.borrow_mut().take();
6755                *observation_count.borrow_mut() += 1;
6756            }
6757        }));
6758
6759        cx.default_global::<()>();
6760        cx.set_global(());
6761        assert_eq!(*observation_count.borrow(), 1);
6762    }
6763
6764    #[crate::test(self)]
6765    fn test_focus(cx: &mut MutableAppContext) {
6766        struct View {
6767            name: String,
6768            events: Arc<Mutex<Vec<String>>>,
6769        }
6770
6771        impl Entity for View {
6772            type Event = ();
6773        }
6774
6775        impl super::View for View {
6776            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6777                Empty::new().boxed()
6778            }
6779
6780            fn ui_name() -> &'static str {
6781                "View"
6782            }
6783
6784            fn on_focus_in(&mut self, focused: AnyViewHandle, cx: &mut ViewContext<Self>) {
6785                if cx.handle().id() == focused.id() {
6786                    self.events.lock().push(format!("{} focused", &self.name));
6787                }
6788            }
6789
6790            fn on_focus_out(&mut self, blurred: AnyViewHandle, cx: &mut ViewContext<Self>) {
6791                if cx.handle().id() == blurred.id() {
6792                    self.events.lock().push(format!("{} blurred", &self.name));
6793                }
6794            }
6795        }
6796
6797        let view_events: Arc<Mutex<Vec<String>>> = Default::default();
6798        let (_, view_1) = cx.add_window(Default::default(), |_| View {
6799            events: view_events.clone(),
6800            name: "view 1".to_string(),
6801        });
6802        let view_2 = cx.add_view(&view_1, |_| View {
6803            events: view_events.clone(),
6804            name: "view 2".to_string(),
6805        });
6806
6807        let observed_events: Arc<Mutex<Vec<String>>> = Default::default();
6808        view_1.update(cx, |_, cx| {
6809            cx.observe_focus(&view_2, {
6810                let observed_events = observed_events.clone();
6811                move |this, view, focused, cx| {
6812                    let label = if focused { "focus" } else { "blur" };
6813                    observed_events.lock().push(format!(
6814                        "{} observed {}'s {}",
6815                        this.name,
6816                        view.read(cx).name,
6817                        label
6818                    ))
6819                }
6820            })
6821            .detach();
6822        });
6823        view_2.update(cx, |_, cx| {
6824            cx.observe_focus(&view_1, {
6825                let observed_events = observed_events.clone();
6826                move |this, view, focused, cx| {
6827                    let label = if focused { "focus" } else { "blur" };
6828                    observed_events.lock().push(format!(
6829                        "{} observed {}'s {}",
6830                        this.name,
6831                        view.read(cx).name,
6832                        label
6833                    ))
6834                }
6835            })
6836            .detach();
6837        });
6838        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
6839        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
6840
6841        view_1.update(cx, |_, cx| {
6842            // Ensure only the latest focus is honored.
6843            cx.focus(&view_2);
6844            cx.focus(&view_1);
6845            cx.focus(&view_2);
6846        });
6847        assert_eq!(
6848            mem::take(&mut *view_events.lock()),
6849            ["view 1 blurred", "view 2 focused"],
6850        );
6851        assert_eq!(
6852            mem::take(&mut *observed_events.lock()),
6853            [
6854                "view 2 observed view 1's blur",
6855                "view 1 observed view 2's focus"
6856            ]
6857        );
6858
6859        view_1.update(cx, |_, cx| cx.focus(&view_1));
6860        assert_eq!(
6861            mem::take(&mut *view_events.lock()),
6862            ["view 2 blurred", "view 1 focused"],
6863        );
6864        assert_eq!(
6865            mem::take(&mut *observed_events.lock()),
6866            [
6867                "view 1 observed view 2's blur",
6868                "view 2 observed view 1's focus"
6869            ]
6870        );
6871
6872        view_1.update(cx, |_, cx| cx.focus(&view_2));
6873        assert_eq!(
6874            mem::take(&mut *view_events.lock()),
6875            ["view 1 blurred", "view 2 focused"],
6876        );
6877        assert_eq!(
6878            mem::take(&mut *observed_events.lock()),
6879            [
6880                "view 2 observed view 1's blur",
6881                "view 1 observed view 2's focus"
6882            ]
6883        );
6884
6885        view_1.update(cx, |_, _| drop(view_2));
6886        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
6887        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
6888    }
6889
6890    #[crate::test(self)]
6891    fn test_deserialize_actions(cx: &mut MutableAppContext) {
6892        #[derive(Clone, Debug, Deserialize, PartialEq, Eq)]
6893        pub struct ComplexAction {
6894            arg: String,
6895            count: usize,
6896        }
6897
6898        actions!(test::something, [SimpleAction]);
6899        impl_actions!(test::something, [ComplexAction]);
6900
6901        cx.add_global_action(move |_: &SimpleAction, _: &mut MutableAppContext| {});
6902        cx.add_global_action(move |_: &ComplexAction, _: &mut MutableAppContext| {});
6903
6904        let action1 = cx
6905            .deserialize_action(
6906                "test::something::ComplexAction",
6907                Some(r#"{"arg": "a", "count": 5}"#),
6908            )
6909            .unwrap();
6910        let action2 = cx
6911            .deserialize_action("test::something::SimpleAction", None)
6912            .unwrap();
6913        assert_eq!(
6914            action1.as_any().downcast_ref::<ComplexAction>().unwrap(),
6915            &ComplexAction {
6916                arg: "a".to_string(),
6917                count: 5,
6918            }
6919        );
6920        assert_eq!(
6921            action2.as_any().downcast_ref::<SimpleAction>().unwrap(),
6922            &SimpleAction
6923        );
6924    }
6925
6926    #[crate::test(self)]
6927    fn test_dispatch_action(cx: &mut MutableAppContext) {
6928        struct ViewA {
6929            id: usize,
6930        }
6931
6932        impl Entity for ViewA {
6933            type Event = ();
6934        }
6935
6936        impl View for ViewA {
6937            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6938                Empty::new().boxed()
6939            }
6940
6941            fn ui_name() -> &'static str {
6942                "View"
6943            }
6944        }
6945
6946        struct ViewB {
6947            id: usize,
6948        }
6949
6950        impl Entity for ViewB {
6951            type Event = ();
6952        }
6953
6954        impl View for ViewB {
6955            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
6956                Empty::new().boxed()
6957            }
6958
6959            fn ui_name() -> &'static str {
6960                "View"
6961            }
6962        }
6963
6964        #[derive(Clone, Default, Deserialize, PartialEq)]
6965        pub struct Action(pub String);
6966
6967        impl_actions!(test, [Action]);
6968
6969        let actions = Rc::new(RefCell::new(Vec::new()));
6970
6971        cx.add_global_action({
6972            let actions = actions.clone();
6973            move |_: &Action, _: &mut MutableAppContext| {
6974                actions.borrow_mut().push("global".to_string());
6975            }
6976        });
6977
6978        cx.add_action({
6979            let actions = actions.clone();
6980            move |view: &mut ViewA, action: &Action, cx| {
6981                assert_eq!(action.0, "bar");
6982                cx.propagate_action();
6983                actions.borrow_mut().push(format!("{} a", view.id));
6984            }
6985        });
6986
6987        cx.add_action({
6988            let actions = actions.clone();
6989            move |view: &mut ViewA, _: &Action, cx| {
6990                if view.id != 1 {
6991                    cx.add_view(|cx| {
6992                        cx.propagate_action(); // Still works on a nested ViewContext
6993                        ViewB { id: 5 }
6994                    });
6995                }
6996                actions.borrow_mut().push(format!("{} b", view.id));
6997            }
6998        });
6999
7000        cx.add_action({
7001            let actions = actions.clone();
7002            move |view: &mut ViewB, _: &Action, cx| {
7003                cx.propagate_action();
7004                actions.borrow_mut().push(format!("{} c", view.id));
7005            }
7006        });
7007
7008        cx.add_action({
7009            let actions = actions.clone();
7010            move |view: &mut ViewB, _: &Action, cx| {
7011                cx.propagate_action();
7012                actions.borrow_mut().push(format!("{} d", view.id));
7013            }
7014        });
7015
7016        cx.capture_action({
7017            let actions = actions.clone();
7018            move |view: &mut ViewA, _: &Action, cx| {
7019                cx.propagate_action();
7020                actions.borrow_mut().push(format!("{} capture", view.id));
7021            }
7022        });
7023
7024        let observed_actions = Rc::new(RefCell::new(Vec::new()));
7025        cx.observe_actions({
7026            let observed_actions = observed_actions.clone();
7027            move |action_id, _| observed_actions.borrow_mut().push(action_id)
7028        })
7029        .detach();
7030
7031        let (window_id, view_1) = cx.add_window(Default::default(), |_| ViewA { id: 1 });
7032        let view_2 = cx.add_view(&view_1, |_| ViewB { id: 2 });
7033        let view_3 = cx.add_view(&view_2, |_| ViewA { id: 3 });
7034        let view_4 = cx.add_view(&view_3, |_| ViewB { id: 4 });
7035
7036        cx.handle_dispatch_action_from_effect(
7037            window_id,
7038            Some(view_4.id()),
7039            &Action("bar".to_string()),
7040        );
7041
7042        assert_eq!(
7043            *actions.borrow(),
7044            vec![
7045                "1 capture",
7046                "3 capture",
7047                "4 d",
7048                "4 c",
7049                "3 b",
7050                "3 a",
7051                "2 d",
7052                "2 c",
7053                "1 b"
7054            ]
7055        );
7056        assert_eq!(*observed_actions.borrow(), [Action::default().id()]);
7057
7058        // Remove view_1, which doesn't propagate the action
7059
7060        let (window_id, view_2) = cx.add_window(Default::default(), |_| ViewB { id: 2 });
7061        let view_3 = cx.add_view(&view_2, |_| ViewA { id: 3 });
7062        let view_4 = cx.add_view(&view_3, |_| ViewB { id: 4 });
7063
7064        actions.borrow_mut().clear();
7065        cx.handle_dispatch_action_from_effect(
7066            window_id,
7067            Some(view_4.id()),
7068            &Action("bar".to_string()),
7069        );
7070
7071        assert_eq!(
7072            *actions.borrow(),
7073            vec![
7074                "3 capture",
7075                "4 d",
7076                "4 c",
7077                "3 b",
7078                "3 a",
7079                "2 d",
7080                "2 c",
7081                "global"
7082            ]
7083        );
7084        assert_eq!(
7085            *observed_actions.borrow(),
7086            [Action::default().id(), Action::default().id()]
7087        );
7088    }
7089
7090    #[crate::test(self)]
7091    fn test_dispatch_keystroke(cx: &mut MutableAppContext) {
7092        #[derive(Clone, Deserialize, PartialEq)]
7093        pub struct Action(String);
7094
7095        impl_actions!(test, [Action]);
7096
7097        struct View {
7098            id: usize,
7099            keymap_context: keymap::Context,
7100        }
7101
7102        impl Entity for View {
7103            type Event = ();
7104        }
7105
7106        impl super::View for View {
7107            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
7108                Empty::new().boxed()
7109            }
7110
7111            fn ui_name() -> &'static str {
7112                "View"
7113            }
7114
7115            fn keymap_context(&self, _: &AppContext) -> keymap::Context {
7116                self.keymap_context.clone()
7117            }
7118        }
7119
7120        impl View {
7121            fn new(id: usize) -> Self {
7122                View {
7123                    id,
7124                    keymap_context: keymap::Context::default(),
7125                }
7126            }
7127        }
7128
7129        let mut view_1 = View::new(1);
7130        let mut view_2 = View::new(2);
7131        let mut view_3 = View::new(3);
7132        view_1.keymap_context.set.insert("a".into());
7133        view_2.keymap_context.set.insert("a".into());
7134        view_2.keymap_context.set.insert("b".into());
7135        view_3.keymap_context.set.insert("a".into());
7136        view_3.keymap_context.set.insert("b".into());
7137        view_3.keymap_context.set.insert("c".into());
7138
7139        let (window_id, view_1) = cx.add_window(Default::default(), |_| view_1);
7140        let view_2 = cx.add_view(&view_1, |_| view_2);
7141        let _view_3 = cx.add_view(&view_2, |cx| {
7142            cx.focus_self();
7143            view_3
7144        });
7145
7146        // This keymap's only binding dispatches an action on view 2 because that view will have
7147        // "a" and "b" in its context, but not "c".
7148        cx.add_bindings(vec![keymap::Binding::new(
7149            "a",
7150            Action("a".to_string()),
7151            Some("a && b && !c"),
7152        )]);
7153
7154        cx.add_bindings(vec![keymap::Binding::new(
7155            "b",
7156            Action("b".to_string()),
7157            None,
7158        )]);
7159
7160        let actions = Rc::new(RefCell::new(Vec::new()));
7161        cx.add_action({
7162            let actions = actions.clone();
7163            move |view: &mut View, action: &Action, cx| {
7164                if action.0 == "a" {
7165                    actions.borrow_mut().push(format!("{} a", view.id));
7166                } else {
7167                    actions
7168                        .borrow_mut()
7169                        .push(format!("{} {}", view.id, action.0));
7170                    cx.propagate_action();
7171                }
7172            }
7173        });
7174
7175        cx.add_global_action({
7176            let actions = actions.clone();
7177            move |action: &Action, _| {
7178                actions.borrow_mut().push(format!("global {}", action.0));
7179            }
7180        });
7181
7182        cx.dispatch_keystroke(window_id, &Keystroke::parse("a").unwrap());
7183
7184        assert_eq!(&*actions.borrow(), &["2 a"]);
7185
7186        actions.borrow_mut().clear();
7187
7188        cx.dispatch_keystroke(window_id, &Keystroke::parse("b").unwrap());
7189
7190        assert_eq!(&*actions.borrow(), &["3 b", "2 b", "1 b", "global b"]);
7191    }
7192
7193    #[crate::test(self)]
7194    async fn test_model_condition(cx: &mut TestAppContext) {
7195        struct Counter(usize);
7196
7197        impl super::Entity for Counter {
7198            type Event = ();
7199        }
7200
7201        impl Counter {
7202            fn inc(&mut self, cx: &mut ModelContext<Self>) {
7203                self.0 += 1;
7204                cx.notify();
7205            }
7206        }
7207
7208        let model = cx.add_model(|_| Counter(0));
7209
7210        let condition1 = model.condition(cx, |model, _| model.0 == 2);
7211        let condition2 = model.condition(cx, |model, _| model.0 == 3);
7212        smol::pin!(condition1, condition2);
7213
7214        model.update(cx, |model, cx| model.inc(cx));
7215        assert_eq!(poll_once(&mut condition1).await, None);
7216        assert_eq!(poll_once(&mut condition2).await, None);
7217
7218        model.update(cx, |model, cx| model.inc(cx));
7219        assert_eq!(poll_once(&mut condition1).await, Some(()));
7220        assert_eq!(poll_once(&mut condition2).await, None);
7221
7222        model.update(cx, |model, cx| model.inc(cx));
7223        assert_eq!(poll_once(&mut condition2).await, Some(()));
7224
7225        model.update(cx, |_, cx| cx.notify());
7226    }
7227
7228    #[crate::test(self)]
7229    #[should_panic]
7230    async fn test_model_condition_timeout(cx: &mut TestAppContext) {
7231        struct Model;
7232
7233        impl super::Entity for Model {
7234            type Event = ();
7235        }
7236
7237        let model = cx.add_model(|_| Model);
7238        model.condition(cx, |_, _| false).await;
7239    }
7240
7241    #[crate::test(self)]
7242    #[should_panic(expected = "model dropped with pending condition")]
7243    async fn test_model_condition_panic_on_drop(cx: &mut TestAppContext) {
7244        struct Model;
7245
7246        impl super::Entity for Model {
7247            type Event = ();
7248        }
7249
7250        let model = cx.add_model(|_| Model);
7251        let condition = model.condition(cx, |_, _| false);
7252        cx.update(|_| drop(model));
7253        condition.await;
7254    }
7255
7256    #[crate::test(self)]
7257    async fn test_view_condition(cx: &mut TestAppContext) {
7258        struct Counter(usize);
7259
7260        impl super::Entity for Counter {
7261            type Event = ();
7262        }
7263
7264        impl super::View for Counter {
7265            fn ui_name() -> &'static str {
7266                "test view"
7267            }
7268
7269            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
7270                Empty::new().boxed()
7271            }
7272        }
7273
7274        impl Counter {
7275            fn inc(&mut self, cx: &mut ViewContext<Self>) {
7276                self.0 += 1;
7277                cx.notify();
7278            }
7279        }
7280
7281        let (_, view) = cx.add_window(|_| Counter(0));
7282
7283        let condition1 = view.condition(cx, |view, _| view.0 == 2);
7284        let condition2 = view.condition(cx, |view, _| view.0 == 3);
7285        smol::pin!(condition1, condition2);
7286
7287        view.update(cx, |view, cx| view.inc(cx));
7288        assert_eq!(poll_once(&mut condition1).await, None);
7289        assert_eq!(poll_once(&mut condition2).await, None);
7290
7291        view.update(cx, |view, cx| view.inc(cx));
7292        assert_eq!(poll_once(&mut condition1).await, Some(()));
7293        assert_eq!(poll_once(&mut condition2).await, None);
7294
7295        view.update(cx, |view, cx| view.inc(cx));
7296        assert_eq!(poll_once(&mut condition2).await, Some(()));
7297        view.update(cx, |_, cx| cx.notify());
7298    }
7299
7300    #[crate::test(self)]
7301    #[should_panic]
7302    async fn test_view_condition_timeout(cx: &mut TestAppContext) {
7303        struct View;
7304
7305        impl super::Entity for View {
7306            type Event = ();
7307        }
7308
7309        impl super::View for View {
7310            fn ui_name() -> &'static str {
7311                "test view"
7312            }
7313
7314            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
7315                Empty::new().boxed()
7316            }
7317        }
7318
7319        let (_, view) = cx.add_window(|_| View);
7320        view.condition(cx, |_, _| false).await;
7321    }
7322
7323    #[crate::test(self)]
7324    #[should_panic(expected = "view dropped with pending condition")]
7325    async fn test_view_condition_panic_on_drop(cx: &mut TestAppContext) {
7326        struct View;
7327
7328        impl super::Entity for View {
7329            type Event = ();
7330        }
7331
7332        impl super::View for View {
7333            fn ui_name() -> &'static str {
7334                "test view"
7335            }
7336
7337            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
7338                Empty::new().boxed()
7339            }
7340        }
7341
7342        let (_, root_view) = cx.add_window(|_| View);
7343        let view = cx.add_view(&root_view, |_| View);
7344
7345        let condition = view.condition(cx, |_, _| false);
7346        cx.update(|_| drop(view));
7347        condition.await;
7348    }
7349
7350    #[crate::test(self)]
7351    fn test_refresh_windows(cx: &mut MutableAppContext) {
7352        struct View(usize);
7353
7354        impl super::Entity for View {
7355            type Event = ();
7356        }
7357
7358        impl super::View for View {
7359            fn ui_name() -> &'static str {
7360                "test view"
7361            }
7362
7363            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
7364                Empty::new().named(format!("render count: {}", post_inc(&mut self.0)))
7365            }
7366        }
7367
7368        let (window_id, root_view) = cx.add_window(Default::default(), |_| View(0));
7369        let presenter = cx.presenters_and_platform_windows[&window_id].0.clone();
7370
7371        assert_eq!(
7372            presenter.borrow().rendered_views[&root_view.id()].name(),
7373            Some("render count: 0")
7374        );
7375
7376        let view = cx.add_view(&root_view, |cx| {
7377            cx.refresh_windows();
7378            View(0)
7379        });
7380
7381        assert_eq!(
7382            presenter.borrow().rendered_views[&root_view.id()].name(),
7383            Some("render count: 1")
7384        );
7385        assert_eq!(
7386            presenter.borrow().rendered_views[&view.id()].name(),
7387            Some("render count: 0")
7388        );
7389
7390        cx.update(|cx| cx.refresh_windows());
7391        assert_eq!(
7392            presenter.borrow().rendered_views[&root_view.id()].name(),
7393            Some("render count: 2")
7394        );
7395        assert_eq!(
7396            presenter.borrow().rendered_views[&view.id()].name(),
7397            Some("render count: 1")
7398        );
7399
7400        cx.update(|cx| {
7401            cx.refresh_windows();
7402            drop(view);
7403        });
7404        assert_eq!(
7405            presenter.borrow().rendered_views[&root_view.id()].name(),
7406            Some("render count: 3")
7407        );
7408        assert_eq!(presenter.borrow().rendered_views.len(), 1);
7409    }
7410
7411    #[crate::test(self)]
7412    async fn test_window_activation(cx: &mut TestAppContext) {
7413        struct View(&'static str);
7414
7415        impl super::Entity for View {
7416            type Event = ();
7417        }
7418
7419        impl super::View for View {
7420            fn ui_name() -> &'static str {
7421                "test view"
7422            }
7423
7424            fn render(&mut self, _: &mut RenderContext<Self>) -> ElementBox {
7425                Empty::new().boxed()
7426            }
7427        }
7428
7429        let events = Rc::new(RefCell::new(Vec::new()));
7430        let (window_1, _) = cx.add_window(|cx: &mut ViewContext<View>| {
7431            cx.observe_window_activation({
7432                let events = events.clone();
7433                move |this, active, _| events.borrow_mut().push((this.0, active))
7434            })
7435            .detach();
7436            View("window 1")
7437        });
7438        assert_eq!(mem::take(&mut *events.borrow_mut()), [("window 1", true)]);
7439
7440        let (window_2, _) = cx.add_window(|cx: &mut ViewContext<View>| {
7441            cx.observe_window_activation({
7442                let events = events.clone();
7443                move |this, active, _| events.borrow_mut().push((this.0, active))
7444            })
7445            .detach();
7446            View("window 2")
7447        });
7448        assert_eq!(
7449            mem::take(&mut *events.borrow_mut()),
7450            [("window 1", false), ("window 2", true)]
7451        );
7452
7453        let (window_3, _) = cx.add_window(|cx: &mut ViewContext<View>| {
7454            cx.observe_window_activation({
7455                let events = events.clone();
7456                move |this, active, _| events.borrow_mut().push((this.0, active))
7457            })
7458            .detach();
7459            View("window 3")
7460        });
7461        assert_eq!(
7462            mem::take(&mut *events.borrow_mut()),
7463            [("window 2", false), ("window 3", true)]
7464        );
7465
7466        cx.simulate_window_activation(Some(window_2));
7467        assert_eq!(
7468            mem::take(&mut *events.borrow_mut()),
7469            [("window 3", false), ("window 2", true)]
7470        );
7471
7472        cx.simulate_window_activation(Some(window_1));
7473        assert_eq!(
7474            mem::take(&mut *events.borrow_mut()),
7475            [("window 2", false), ("window 1", true)]
7476        );
7477
7478        cx.simulate_window_activation(Some(window_3));
7479        assert_eq!(
7480            mem::take(&mut *events.borrow_mut()),
7481            [("window 1", false), ("window 3", true)]
7482        );
7483
7484        cx.simulate_window_activation(Some(window_3));
7485        assert_eq!(mem::take(&mut *events.borrow_mut()), []);
7486    }
7487}