app.rs

   1pub mod action;
   2mod callback_collection;
   3mod menu;
   4pub(crate) mod ref_counts;
   5#[cfg(any(test, feature = "test-support"))]
   6pub mod test_app_context;
   7pub(crate) mod window;
   8mod window_input_handler;
   9
  10use std::{
  11    any::{type_name, Any, TypeId},
  12    cell::RefCell,
  13    fmt::{self, Debug},
  14    hash::{Hash, Hasher},
  15    marker::PhantomData,
  16    mem,
  17    ops::{Deref, DerefMut, Range},
  18    path::{Path, PathBuf},
  19    pin::Pin,
  20    rc::{self, Rc},
  21    sync::{Arc, Weak},
  22    time::Duration,
  23};
  24
  25use anyhow::{anyhow, Context, Result};
  26use parking_lot::Mutex;
  27use postage::oneshot;
  28use smallvec::SmallVec;
  29use smol::prelude::*;
  30use util::ResultExt;
  31use uuid::Uuid;
  32
  33pub use action::*;
  34use callback_collection::CallbackCollection;
  35use collections::{hash_map::Entry, BTreeMap, HashMap, HashSet, VecDeque};
  36pub use menu::*;
  37use platform::Event;
  38#[cfg(any(test, feature = "test-support"))]
  39use ref_counts::LeakDetector;
  40#[cfg(any(test, feature = "test-support"))]
  41pub use test_app_context::{ContextHandle, TestAppContext};
  42use window_input_handler::WindowInputHandler;
  43
  44use crate::{
  45    elements::{AnyElement, AnyRootElement, RootElement},
  46    executor::{self, Task},
  47    fonts::TextStyle,
  48    json,
  49    keymap_matcher::{self, Binding, KeymapContext, KeymapMatcher, Keystroke, MatchResult},
  50    platform::{
  51        self, FontSystem, KeyDownEvent, KeyUpEvent, ModifiersChangedEvent, MouseButton,
  52        PathPromptOptions, Platform, PromptLevel, WindowBounds, WindowOptions,
  53    },
  54    util::post_inc,
  55    window::{Window, WindowContext},
  56    AssetCache, AssetSource, ClipboardItem, FontCache, MouseRegionId,
  57};
  58
  59use self::ref_counts::RefCounts;
  60
  61pub trait Entity: 'static {
  62    type Event;
  63
  64    fn release(&mut self, _: &mut AppContext) {}
  65    fn app_will_quit(
  66        &mut self,
  67        _: &mut AppContext,
  68    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
  69        None
  70    }
  71}
  72
  73pub trait View: Entity + Sized {
  74    fn ui_name() -> &'static str;
  75    fn render(&mut self, cx: &mut ViewContext<'_, '_, Self>) -> AnyElement<Self>;
  76    fn focus_in(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  77    fn focus_out(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  78    fn key_down(&mut self, _: &KeyDownEvent, _: &mut ViewContext<Self>) -> bool {
  79        false
  80    }
  81    fn key_up(&mut self, _: &KeyUpEvent, _: &mut ViewContext<Self>) -> bool {
  82        false
  83    }
  84    fn modifiers_changed(&mut self, _: &ModifiersChangedEvent, _: &mut ViewContext<Self>) -> bool {
  85        false
  86    }
  87
  88    fn update_keymap_context(&self, keymap: &mut keymap_matcher::KeymapContext, _: &AppContext) {
  89        Self::reset_to_default_keymap_context(keymap);
  90    }
  91
  92    fn reset_to_default_keymap_context(keymap: &mut keymap_matcher::KeymapContext) {
  93        keymap.clear();
  94        keymap.add_identifier(Self::ui_name());
  95    }
  96
  97    fn debug_json(&self, _: &AppContext) -> serde_json::Value {
  98        serde_json::Value::Null
  99    }
 100
 101    fn text_for_range(&self, _: Range<usize>, _: &AppContext) -> Option<String> {
 102        None
 103    }
 104    fn selected_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 105        None
 106    }
 107    fn marked_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 108        None
 109    }
 110    fn unmark_text(&mut self, _: &mut ViewContext<Self>) {}
 111    fn replace_text_in_range(
 112        &mut self,
 113        _: Option<Range<usize>>,
 114        _: &str,
 115        _: &mut ViewContext<Self>,
 116    ) {
 117    }
 118    fn replace_and_mark_text_in_range(
 119        &mut self,
 120        _: Option<Range<usize>>,
 121        _: &str,
 122        _: Option<Range<usize>>,
 123        _: &mut ViewContext<Self>,
 124    ) {
 125    }
 126}
 127
 128pub trait BorrowAppContext {
 129    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T;
 130    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T;
 131}
 132
 133pub trait BorrowWindowContext {
 134    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T;
 135    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T;
 136}
 137
 138#[derive(Clone)]
 139pub struct App(Rc<RefCell<AppContext>>);
 140
 141impl App {
 142    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 143        let platform = platform::current::platform();
 144        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 145        let foreground_platform = platform::current::foreground_platform(foreground.clone());
 146        let app = Self(Rc::new(RefCell::new(AppContext::new(
 147            foreground,
 148            Arc::new(executor::Background::new()),
 149            platform.clone(),
 150            foreground_platform.clone(),
 151            Arc::new(FontCache::new(platform.fonts())),
 152            Default::default(),
 153            asset_source,
 154        ))));
 155
 156        foreground_platform.on_event(Box::new({
 157            let cx = app.0.clone();
 158            move |event| {
 159                if let Event::KeyDown(KeyDownEvent { keystroke, .. }) = &event {
 160                    // Allow system menu "cmd-?" shortcut to be overridden
 161                    if keystroke.cmd
 162                        && !keystroke.shift
 163                        && !keystroke.alt
 164                        && !keystroke.function
 165                        && keystroke.key == "?"
 166                    {
 167                        if cx
 168                            .borrow_mut()
 169                            .update_active_window(|cx| cx.dispatch_keystroke(keystroke))
 170                            .unwrap_or(false)
 171                        {
 172                            return true;
 173                        }
 174                    }
 175                }
 176                false
 177            }
 178        }));
 179        foreground_platform.on_quit(Box::new({
 180            let cx = app.0.clone();
 181            move || {
 182                cx.borrow_mut().quit();
 183            }
 184        }));
 185        setup_menu_handlers(foreground_platform.as_ref(), &app);
 186
 187        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 188        Ok(app)
 189    }
 190
 191    pub fn background(&self) -> Arc<executor::Background> {
 192        self.0.borrow().background().clone()
 193    }
 194
 195    pub fn on_become_active<F>(self, mut callback: F) -> Self
 196    where
 197        F: 'static + FnMut(&mut AppContext),
 198    {
 199        let cx = self.0.clone();
 200        self.0
 201            .borrow_mut()
 202            .foreground_platform
 203            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 204        self
 205    }
 206
 207    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 208    where
 209        F: 'static + FnMut(&mut AppContext),
 210    {
 211        let cx = self.0.clone();
 212        self.0
 213            .borrow_mut()
 214            .foreground_platform
 215            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 216        self
 217    }
 218
 219    pub fn on_quit<F>(&mut self, mut callback: F) -> &mut Self
 220    where
 221        F: 'static + FnMut(&mut AppContext),
 222    {
 223        let cx = self.0.clone();
 224        self.0
 225            .borrow_mut()
 226            .foreground_platform
 227            .on_quit(Box::new(move || callback(&mut *cx.borrow_mut())));
 228        self
 229    }
 230
 231    /// Handle the application being re-activated when no windows are open.
 232    pub fn on_reopen<F>(&mut self, mut callback: F) -> &mut Self
 233    where
 234        F: 'static + FnMut(&mut AppContext),
 235    {
 236        let cx = self.0.clone();
 237        self.0
 238            .borrow_mut()
 239            .foreground_platform
 240            .on_reopen(Box::new(move || callback(&mut *cx.borrow_mut())));
 241        self
 242    }
 243
 244    pub fn on_event<F>(&mut self, mut callback: F) -> &mut Self
 245    where
 246        F: 'static + FnMut(Event, &mut AppContext) -> bool,
 247    {
 248        let cx = self.0.clone();
 249        self.0
 250            .borrow_mut()
 251            .foreground_platform
 252            .on_event(Box::new(move |event| {
 253                callback(event, &mut *cx.borrow_mut())
 254            }));
 255        self
 256    }
 257
 258    pub fn on_open_urls<F>(&mut self, mut callback: F) -> &mut Self
 259    where
 260        F: 'static + FnMut(Vec<String>, &mut AppContext),
 261    {
 262        let cx = self.0.clone();
 263        self.0
 264            .borrow_mut()
 265            .foreground_platform
 266            .on_open_urls(Box::new(move |urls| callback(urls, &mut *cx.borrow_mut())));
 267        self
 268    }
 269
 270    pub fn run<F>(self, on_finish_launching: F)
 271    where
 272        F: 'static + FnOnce(&mut AppContext),
 273    {
 274        let platform = self.0.borrow().foreground_platform.clone();
 275        platform.run(Box::new(move || {
 276            let mut cx = self.0.borrow_mut();
 277            let cx = &mut *cx;
 278            crate::views::init(cx);
 279            on_finish_launching(cx);
 280        }))
 281    }
 282
 283    pub fn platform(&self) -> Arc<dyn Platform> {
 284        self.0.borrow().platform.clone()
 285    }
 286
 287    pub fn font_cache(&self) -> Arc<FontCache> {
 288        self.0.borrow().font_cache.clone()
 289    }
 290
 291    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 292        let mut state = self.0.borrow_mut();
 293        let result = state.update(callback);
 294        state.pending_notifications.clear();
 295        result
 296    }
 297
 298    fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 299        &mut self,
 300        window_id: usize,
 301        callback: F,
 302    ) -> Option<T> {
 303        let mut state = self.0.borrow_mut();
 304        let result = state.update_window(window_id, callback);
 305        state.pending_notifications.clear();
 306        result
 307    }
 308}
 309
 310#[derive(Clone)]
 311pub struct AsyncAppContext(Rc<RefCell<AppContext>>);
 312
 313impl AsyncAppContext {
 314    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 315    where
 316        F: FnOnce(AsyncAppContext) -> Fut,
 317        Fut: 'static + Future<Output = T>,
 318        T: 'static,
 319    {
 320        self.0.borrow().foreground.spawn(f(self.clone()))
 321    }
 322
 323    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 324        callback(&*self.0.borrow())
 325    }
 326
 327    pub fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 328        self.0.borrow_mut().update(callback)
 329    }
 330
 331    pub fn read_window<T, F: FnOnce(&WindowContext) -> T>(
 332        &self,
 333        window_id: usize,
 334        callback: F,
 335    ) -> Option<T> {
 336        self.0.borrow_mut().read_window(window_id, callback)
 337    }
 338
 339    pub fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 340        &mut self,
 341        window_id: usize,
 342        callback: F,
 343    ) -> Option<T> {
 344        self.0.borrow_mut().update_window(window_id, callback)
 345    }
 346
 347    pub fn debug_elements(&self, window_id: usize) -> Option<json::Value> {
 348        self.0.borrow().read_window(window_id, |cx| {
 349            let root_view = cx.window.root_view();
 350            let root_element = cx.window.rendered_views.get(&root_view.id())?;
 351            root_element.debug(cx).log_err()
 352        })?
 353    }
 354
 355    pub fn dispatch_action(
 356        &mut self,
 357        window_id: usize,
 358        view_id: usize,
 359        action: &dyn Action,
 360    ) -> Result<()> {
 361        self.0
 362            .borrow_mut()
 363            .update_window(window_id, |window| {
 364                window.dispatch_action(Some(view_id), action);
 365            })
 366            .ok_or_else(|| anyhow!("window not found"))
 367    }
 368
 369    pub fn available_actions(
 370        &self,
 371        window_id: usize,
 372        view_id: usize,
 373    ) -> Vec<(&'static str, Box<dyn Action>, SmallVec<[Binding; 1]>)> {
 374        self.read_window(window_id, |cx| cx.available_actions(view_id))
 375            .unwrap_or_default()
 376    }
 377
 378    pub fn has_window(&self, window_id: usize) -> bool {
 379        self.read(|cx| cx.windows.contains_key(&window_id))
 380    }
 381
 382    pub fn window_is_active(&self, window_id: usize) -> bool {
 383        self.read(|cx| cx.windows.get(&window_id).map_or(false, |w| w.is_active))
 384    }
 385
 386    pub fn root_view(&self, window_id: usize) -> Option<AnyViewHandle> {
 387        self.read(|cx| cx.windows.get(&window_id).map(|w| w.root_view().clone()))
 388    }
 389
 390    pub fn window_ids(&self) -> Vec<usize> {
 391        self.read(|cx| cx.windows.keys().copied().collect())
 392    }
 393
 394    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 395    where
 396        T: Entity,
 397        F: FnOnce(&mut ModelContext<T>) -> T,
 398    {
 399        self.update(|cx| cx.add_model(build_model))
 400    }
 401
 402    pub fn add_window<T, F>(
 403        &mut self,
 404        window_options: WindowOptions,
 405        build_root_view: F,
 406    ) -> (usize, ViewHandle<T>)
 407    where
 408        T: View,
 409        F: FnOnce(&mut ViewContext<T>) -> T,
 410    {
 411        self.update(|cx| cx.add_window(window_options, build_root_view))
 412    }
 413
 414    pub fn remove_window(&mut self, window_id: usize) {
 415        self.update_window(window_id, |cx| cx.remove_window());
 416    }
 417
 418    pub fn activate_window(&mut self, window_id: usize) {
 419        self.update_window(window_id, |cx| cx.activate_window());
 420    }
 421
 422    // TODO: Can we eliminate this method and move it to WindowContext then call it with update_window?s
 423    pub fn prompt(
 424        &mut self,
 425        window_id: usize,
 426        level: PromptLevel,
 427        msg: &str,
 428        answers: &[&str],
 429    ) -> Option<oneshot::Receiver<usize>> {
 430        self.update_window(window_id, |cx| cx.prompt(level, msg, answers))
 431    }
 432
 433    pub fn platform(&self) -> Arc<dyn Platform> {
 434        self.0.borrow().platform().clone()
 435    }
 436
 437    pub fn foreground(&self) -> Rc<executor::Foreground> {
 438        self.0.borrow().foreground.clone()
 439    }
 440
 441    pub fn background(&self) -> Arc<executor::Background> {
 442        self.0.borrow().background.clone()
 443    }
 444}
 445
 446impl BorrowAppContext for AsyncAppContext {
 447    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
 448        self.0.borrow().read_with(f)
 449    }
 450
 451    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
 452        self.0.borrow_mut().update(f)
 453    }
 454}
 455
 456type ActionCallback = dyn FnMut(&mut dyn AnyView, &dyn Action, &mut WindowContext, usize);
 457type GlobalActionCallback = dyn FnMut(&dyn Action, &mut AppContext);
 458
 459type SubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool>;
 460type GlobalSubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 461type ObservationCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 462type GlobalObservationCallback = Box<dyn FnMut(&mut AppContext)>;
 463type FocusObservationCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 464type ReleaseObservationCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 465type ActionObservationCallback = Box<dyn FnMut(TypeId, &mut AppContext)>;
 466type WindowActivationCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 467type WindowFullscreenCallback = Box<dyn FnMut(bool, &mut WindowContext) -> bool>;
 468type WindowBoundsCallback = Box<dyn FnMut(WindowBounds, Uuid, &mut WindowContext) -> bool>;
 469type KeystrokeCallback =
 470    Box<dyn FnMut(&Keystroke, &MatchResult, Option<&Box<dyn Action>>, &mut WindowContext) -> bool>;
 471type ActiveLabeledTasksCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 472type DeserializeActionCallback = fn(json: serde_json::Value) -> anyhow::Result<Box<dyn Action>>;
 473type WindowShouldCloseSubscriptionCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 474
 475pub struct AppContext {
 476    models: HashMap<usize, Box<dyn AnyModel>>,
 477    views: HashMap<(usize, usize), Box<dyn AnyView>>,
 478    views_metadata: HashMap<(usize, usize), ViewMetadata>,
 479    windows: HashMap<usize, Window>,
 480    globals: HashMap<TypeId, Box<dyn Any>>,
 481    element_states: HashMap<ElementStateId, Box<dyn Any>>,
 482    background: Arc<executor::Background>,
 483    ref_counts: Arc<Mutex<RefCounts>>,
 484
 485    weak_self: Option<rc::Weak<RefCell<Self>>>,
 486    platform: Arc<dyn Platform>,
 487    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 488    pub asset_cache: Arc<AssetCache>,
 489    font_system: Arc<dyn FontSystem>,
 490    pub font_cache: Arc<FontCache>,
 491    action_deserializers: HashMap<&'static str, (TypeId, DeserializeActionCallback)>,
 492    capture_actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 493    // Entity Types -> { Action Types -> Action Handlers }
 494    actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 495    // Action Types -> Action Handlers
 496    global_actions: HashMap<TypeId, Box<GlobalActionCallback>>,
 497    keystroke_matcher: KeymapMatcher,
 498    next_entity_id: usize,
 499    next_window_id: usize,
 500    next_subscription_id: usize,
 501    frame_count: usize,
 502
 503    subscriptions: CallbackCollection<usize, SubscriptionCallback>,
 504    global_subscriptions: CallbackCollection<TypeId, GlobalSubscriptionCallback>,
 505    observations: CallbackCollection<usize, ObservationCallback>,
 506    global_observations: CallbackCollection<TypeId, GlobalObservationCallback>,
 507    focus_observations: CallbackCollection<usize, FocusObservationCallback>,
 508    release_observations: CallbackCollection<usize, ReleaseObservationCallback>,
 509    action_dispatch_observations: CallbackCollection<(), ActionObservationCallback>,
 510    window_activation_observations: CallbackCollection<usize, WindowActivationCallback>,
 511    window_fullscreen_observations: CallbackCollection<usize, WindowFullscreenCallback>,
 512    window_bounds_observations: CallbackCollection<usize, WindowBoundsCallback>,
 513    keystroke_observations: CallbackCollection<usize, KeystrokeCallback>,
 514    active_labeled_task_observations: CallbackCollection<(), ActiveLabeledTasksCallback>,
 515
 516    foreground: Rc<executor::Foreground>,
 517    pending_effects: VecDeque<Effect>,
 518    pending_notifications: HashSet<usize>,
 519    pending_global_notifications: HashSet<TypeId>,
 520    pending_flushes: usize,
 521    flushing_effects: bool,
 522    halt_action_dispatch: bool,
 523    next_labeled_task_id: usize,
 524    active_labeled_tasks: BTreeMap<usize, &'static str>,
 525}
 526
 527impl AppContext {
 528    fn new(
 529        foreground: Rc<executor::Foreground>,
 530        background: Arc<executor::Background>,
 531        platform: Arc<dyn platform::Platform>,
 532        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 533        font_cache: Arc<FontCache>,
 534        ref_counts: RefCounts,
 535        asset_source: impl AssetSource,
 536    ) -> Self {
 537        Self {
 538            models: Default::default(),
 539            views: Default::default(),
 540            views_metadata: Default::default(),
 541            windows: Default::default(),
 542            globals: Default::default(),
 543            element_states: Default::default(),
 544            ref_counts: Arc::new(Mutex::new(ref_counts)),
 545            background,
 546
 547            weak_self: None,
 548            font_system: platform.fonts(),
 549            platform,
 550            foreground_platform,
 551            font_cache,
 552            asset_cache: Arc::new(AssetCache::new(asset_source)),
 553            action_deserializers: Default::default(),
 554            capture_actions: Default::default(),
 555            actions: Default::default(),
 556            global_actions: Default::default(),
 557            keystroke_matcher: KeymapMatcher::default(),
 558            next_entity_id: 0,
 559            next_window_id: 0,
 560            next_subscription_id: 0,
 561            frame_count: 0,
 562            subscriptions: Default::default(),
 563            global_subscriptions: Default::default(),
 564            observations: Default::default(),
 565            focus_observations: Default::default(),
 566            release_observations: Default::default(),
 567            global_observations: Default::default(),
 568            window_activation_observations: Default::default(),
 569            window_fullscreen_observations: Default::default(),
 570            window_bounds_observations: Default::default(),
 571            keystroke_observations: Default::default(),
 572            action_dispatch_observations: Default::default(),
 573            active_labeled_task_observations: Default::default(),
 574            foreground,
 575            pending_effects: VecDeque::new(),
 576            pending_notifications: Default::default(),
 577            pending_global_notifications: Default::default(),
 578            pending_flushes: 0,
 579            flushing_effects: false,
 580            halt_action_dispatch: false,
 581            next_labeled_task_id: 0,
 582            active_labeled_tasks: Default::default(),
 583        }
 584    }
 585
 586    pub fn background(&self) -> &Arc<executor::Background> {
 587        &self.background
 588    }
 589
 590    pub fn font_cache(&self) -> &Arc<FontCache> {
 591        &self.font_cache
 592    }
 593
 594    pub fn platform(&self) -> &Arc<dyn Platform> {
 595        &self.platform
 596    }
 597
 598    pub fn has_global<T: 'static>(&self) -> bool {
 599        self.globals.contains_key(&TypeId::of::<T>())
 600    }
 601
 602    pub fn global<T: 'static>(&self) -> &T {
 603        if let Some(global) = self.globals.get(&TypeId::of::<T>()) {
 604            global.downcast_ref().unwrap()
 605        } else {
 606            panic!("no global has been added for {}", type_name::<T>());
 607        }
 608    }
 609
 610    pub fn upgrade(&self) -> App {
 611        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 612    }
 613
 614    fn quit(&mut self) {
 615        let mut futures = Vec::new();
 616
 617        self.update(|cx| {
 618            for model_id in cx.models.keys().copied().collect::<Vec<_>>() {
 619                let mut model = cx.models.remove(&model_id).unwrap();
 620                futures.extend(model.app_will_quit(cx));
 621                cx.models.insert(model_id, model);
 622            }
 623
 624            for view_id in cx.views.keys().copied().collect::<Vec<_>>() {
 625                let mut view = cx.views.remove(&view_id).unwrap();
 626                futures.extend(view.app_will_quit(cx));
 627                cx.views.insert(view_id, view);
 628            }
 629        });
 630
 631        self.windows.clear();
 632        self.flush_effects();
 633
 634        let futures = futures::future::join_all(futures);
 635        if self
 636            .background
 637            .block_with_timeout(Duration::from_millis(100), futures)
 638            .is_err()
 639        {
 640            log::error!("timed out waiting on app_will_quit");
 641        }
 642    }
 643
 644    pub fn foreground(&self) -> &Rc<executor::Foreground> {
 645        &self.foreground
 646    }
 647
 648    pub fn deserialize_action(
 649        &self,
 650        name: &str,
 651        argument: Option<serde_json::Value>,
 652    ) -> Result<Box<dyn Action>> {
 653        let callback = self
 654            .action_deserializers
 655            .get(name)
 656            .ok_or_else(|| anyhow!("unknown action {}", name))?
 657            .1;
 658        callback(argument.unwrap_or_else(|| serde_json::Value::Object(Default::default())))
 659            .with_context(|| format!("invalid data for action {}", name))
 660    }
 661
 662    pub fn add_action<A, V, F, R>(&mut self, handler: F)
 663    where
 664        A: Action,
 665        V: View,
 666        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 667    {
 668        self.add_action_internal(handler, false)
 669    }
 670
 671    pub fn capture_action<A, V, F>(&mut self, handler: F)
 672    where
 673        A: Action,
 674        V: View,
 675        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
 676    {
 677        self.add_action_internal(handler, true)
 678    }
 679
 680    fn add_action_internal<A, V, F, R>(&mut self, mut handler: F, capture: bool)
 681    where
 682        A: Action,
 683        V: View,
 684        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 685    {
 686        let handler = Box::new(
 687            move |view: &mut dyn AnyView,
 688                  action: &dyn Action,
 689                  cx: &mut WindowContext,
 690                  view_id: usize| {
 691                let action = action.as_any().downcast_ref().unwrap();
 692                let mut cx = ViewContext::mutable(cx, view_id);
 693                handler(
 694                    view.as_any_mut()
 695                        .downcast_mut()
 696                        .expect("downcast is type safe"),
 697                    action,
 698                    &mut cx,
 699                );
 700            },
 701        );
 702
 703        self.action_deserializers
 704            .entry(A::qualified_name())
 705            .or_insert((TypeId::of::<A>(), A::from_json_str));
 706
 707        let actions = if capture {
 708            &mut self.capture_actions
 709        } else {
 710            &mut self.actions
 711        };
 712
 713        actions
 714            .entry(TypeId::of::<V>())
 715            .or_default()
 716            .entry(TypeId::of::<A>())
 717            .or_default()
 718            .push(handler);
 719    }
 720
 721    pub fn add_async_action<A, V, F>(&mut self, mut handler: F)
 722    where
 723        A: Action,
 724        V: View,
 725        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> Option<Task<Result<()>>>,
 726    {
 727        self.add_action(move |view, action, cx| {
 728            if let Some(task) = handler(view, action, cx) {
 729                task.detach_and_log_err(cx);
 730            }
 731        })
 732    }
 733
 734    pub fn add_global_action<A, F>(&mut self, mut handler: F)
 735    where
 736        A: Action,
 737        F: 'static + FnMut(&A, &mut AppContext),
 738    {
 739        let handler = Box::new(move |action: &dyn Action, cx: &mut AppContext| {
 740            let action = action.as_any().downcast_ref().unwrap();
 741            handler(action, cx);
 742        });
 743
 744        self.action_deserializers
 745            .entry(A::qualified_name())
 746            .or_insert((TypeId::of::<A>(), A::from_json_str));
 747
 748        if self
 749            .global_actions
 750            .insert(TypeId::of::<A>(), handler)
 751            .is_some()
 752        {
 753            panic!(
 754                "registered multiple global handlers for {}",
 755                type_name::<A>()
 756            );
 757        }
 758    }
 759
 760    pub fn view_ui_name(&self, window_id: usize, view_id: usize) -> Option<&'static str> {
 761        Some(self.views.get(&(window_id, view_id))?.ui_name())
 762    }
 763
 764    pub fn view_type_id(&self, window_id: usize, view_id: usize) -> Option<TypeId> {
 765        self.views_metadata
 766            .get(&(window_id, view_id))
 767            .map(|metadata| metadata.type_id)
 768    }
 769
 770    pub fn active_labeled_tasks<'a>(
 771        &'a self,
 772    ) -> impl DoubleEndedIterator<Item = &'static str> + 'a {
 773        self.active_labeled_tasks.values().cloned()
 774    }
 775
 776    pub(crate) fn start_frame(&mut self) {
 777        self.frame_count += 1;
 778    }
 779
 780    pub fn update<T, F: FnOnce(&mut Self) -> T>(&mut self, callback: F) -> T {
 781        self.pending_flushes += 1;
 782        let result = callback(self);
 783        self.flush_effects();
 784        result
 785    }
 786
 787    pub fn read_window<T, F: FnOnce(&WindowContext) -> T>(
 788        &self,
 789        window_id: usize,
 790        callback: F,
 791    ) -> Option<T> {
 792        let window = self.windows.get(&window_id)?;
 793        let window_context = WindowContext::immutable(self, &window, window_id);
 794        Some(callback(&window_context))
 795    }
 796
 797    pub fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 798        &mut self,
 799        window_id: usize,
 800        callback: F,
 801    ) -> Option<T> {
 802        self.update(|app_context| {
 803            let mut window = app_context.windows.remove(&window_id)?;
 804            let mut window_context = WindowContext::mutable(app_context, &mut window, window_id);
 805            let result = callback(&mut window_context);
 806            if !window_context.removed {
 807                app_context.windows.insert(window_id, window);
 808            }
 809            Some(result)
 810        })
 811    }
 812
 813    pub fn update_active_window<T, F: FnOnce(&mut WindowContext) -> T>(
 814        &mut self,
 815        callback: F,
 816    ) -> Option<T> {
 817        self.platform
 818            .main_window_id()
 819            .and_then(|id| self.update_window(id, callback))
 820    }
 821
 822    pub fn prompt_for_paths(
 823        &self,
 824        options: PathPromptOptions,
 825    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
 826        self.foreground_platform.prompt_for_paths(options)
 827    }
 828
 829    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
 830        self.foreground_platform.prompt_for_new_path(directory)
 831    }
 832
 833    pub fn reveal_path(&self, path: &Path) {
 834        self.foreground_platform.reveal_path(path)
 835    }
 836
 837    pub fn emit_global<E: Any>(&mut self, payload: E) {
 838        self.pending_effects.push_back(Effect::GlobalEvent {
 839            payload: Box::new(payload),
 840        });
 841    }
 842
 843    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 844    where
 845        E: Entity,
 846        E::Event: 'static,
 847        H: Handle<E>,
 848        F: 'static + FnMut(H, &E::Event, &mut Self),
 849    {
 850        self.subscribe_internal(handle, move |handle, event, cx| {
 851            callback(handle, event, cx);
 852            true
 853        })
 854    }
 855
 856    pub fn subscribe_global<E, F>(&mut self, mut callback: F) -> Subscription
 857    where
 858        E: Any,
 859        F: 'static + FnMut(&E, &mut Self),
 860    {
 861        let subscription_id = post_inc(&mut self.next_subscription_id);
 862        let type_id = TypeId::of::<E>();
 863        self.pending_effects.push_back(Effect::GlobalSubscription {
 864            type_id,
 865            subscription_id,
 866            callback: Box::new(move |payload, cx| {
 867                let payload = payload.downcast_ref().expect("downcast is type safe");
 868                callback(payload, cx)
 869            }),
 870        });
 871        Subscription::GlobalSubscription(
 872            self.global_subscriptions
 873                .subscribe(type_id, subscription_id),
 874        )
 875    }
 876
 877    pub fn observe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 878    where
 879        E: Entity,
 880        E::Event: 'static,
 881        H: Handle<E>,
 882        F: 'static + FnMut(H, &mut Self),
 883    {
 884        self.observe_internal(handle, move |handle, cx| {
 885            callback(handle, cx);
 886            true
 887        })
 888    }
 889
 890    fn subscribe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 891    where
 892        E: Entity,
 893        E::Event: 'static,
 894        H: Handle<E>,
 895        F: 'static + FnMut(H, &E::Event, &mut Self) -> bool,
 896    {
 897        let subscription_id = post_inc(&mut self.next_subscription_id);
 898        let emitter = handle.downgrade();
 899        self.pending_effects.push_back(Effect::Subscription {
 900            entity_id: handle.id(),
 901            subscription_id,
 902            callback: Box::new(move |payload, cx| {
 903                if let Some(emitter) = H::upgrade_from(&emitter, cx) {
 904                    let payload = payload.downcast_ref().expect("downcast is type safe");
 905                    callback(emitter, payload, cx)
 906                } else {
 907                    false
 908                }
 909            }),
 910        });
 911        Subscription::Subscription(self.subscriptions.subscribe(handle.id(), subscription_id))
 912    }
 913
 914    fn observe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 915    where
 916        E: Entity,
 917        E::Event: 'static,
 918        H: Handle<E>,
 919        F: 'static + FnMut(H, &mut Self) -> bool,
 920    {
 921        let subscription_id = post_inc(&mut self.next_subscription_id);
 922        let observed = handle.downgrade();
 923        let entity_id = handle.id();
 924        self.pending_effects.push_back(Effect::Observation {
 925            entity_id,
 926            subscription_id,
 927            callback: Box::new(move |cx| {
 928                if let Some(observed) = H::upgrade_from(&observed, cx) {
 929                    callback(observed, cx)
 930                } else {
 931                    false
 932                }
 933            }),
 934        });
 935        Subscription::Observation(self.observations.subscribe(entity_id, subscription_id))
 936    }
 937
 938    fn observe_focus<F, V>(&mut self, handle: &ViewHandle<V>, mut callback: F) -> Subscription
 939    where
 940        F: 'static + FnMut(ViewHandle<V>, bool, &mut WindowContext) -> bool,
 941        V: View,
 942    {
 943        let subscription_id = post_inc(&mut self.next_subscription_id);
 944        let observed = handle.downgrade();
 945        let view_id = handle.id();
 946
 947        self.pending_effects.push_back(Effect::FocusObservation {
 948            view_id,
 949            subscription_id,
 950            callback: Box::new(move |focused, cx| {
 951                if let Some(observed) = observed.upgrade(cx) {
 952                    callback(observed, focused, cx)
 953                } else {
 954                    false
 955                }
 956            }),
 957        });
 958        Subscription::FocusObservation(self.focus_observations.subscribe(view_id, subscription_id))
 959    }
 960
 961    pub fn observe_global<G, F>(&mut self, mut observe: F) -> Subscription
 962    where
 963        G: Any,
 964        F: 'static + FnMut(&mut AppContext),
 965    {
 966        let type_id = TypeId::of::<G>();
 967        let id = post_inc(&mut self.next_subscription_id);
 968
 969        self.global_observations.add_callback(
 970            type_id,
 971            id,
 972            Box::new(move |cx: &mut AppContext| observe(cx)),
 973        );
 974        Subscription::GlobalObservation(self.global_observations.subscribe(type_id, id))
 975    }
 976
 977    pub fn observe_default_global<G, F>(&mut self, observe: F) -> Subscription
 978    where
 979        G: Any + Default,
 980        F: 'static + FnMut(&mut AppContext),
 981    {
 982        if !self.has_global::<G>() {
 983            self.set_global(G::default());
 984        }
 985        self.observe_global::<G, F>(observe)
 986    }
 987
 988    pub fn observe_release<E, H, F>(&mut self, handle: &H, callback: F) -> Subscription
 989    where
 990        E: Entity,
 991        E::Event: 'static,
 992        H: Handle<E>,
 993        F: 'static + FnOnce(&E, &mut Self),
 994    {
 995        let id = post_inc(&mut self.next_subscription_id);
 996        let mut callback = Some(callback);
 997        self.release_observations.add_callback(
 998            handle.id(),
 999            id,
1000            Box::new(move |released, cx| {
1001                let released = released.downcast_ref().unwrap();
1002                if let Some(callback) = callback.take() {
1003                    callback(released, cx)
1004                }
1005            }),
1006        );
1007        Subscription::ReleaseObservation(self.release_observations.subscribe(handle.id(), id))
1008    }
1009
1010    pub fn observe_actions<F>(&mut self, callback: F) -> Subscription
1011    where
1012        F: 'static + FnMut(TypeId, &mut AppContext),
1013    {
1014        let subscription_id = post_inc(&mut self.next_subscription_id);
1015        self.action_dispatch_observations
1016            .add_callback((), subscription_id, Box::new(callback));
1017        Subscription::ActionObservation(
1018            self.action_dispatch_observations
1019                .subscribe((), subscription_id),
1020        )
1021    }
1022
1023    fn observe_active_labeled_tasks<F>(&mut self, callback: F) -> Subscription
1024    where
1025        F: 'static + FnMut(&mut AppContext) -> bool,
1026    {
1027        let subscription_id = post_inc(&mut self.next_subscription_id);
1028        self.active_labeled_task_observations
1029            .add_callback((), subscription_id, Box::new(callback));
1030        Subscription::ActiveLabeledTasksObservation(
1031            self.active_labeled_task_observations
1032                .subscribe((), subscription_id),
1033        )
1034    }
1035
1036    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1037        self.pending_effects.push_back(Effect::Deferred {
1038            callback: Box::new(callback),
1039            after_window_update: false,
1040        })
1041    }
1042
1043    pub fn after_window_update(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1044        self.pending_effects.push_back(Effect::Deferred {
1045            callback: Box::new(callback),
1046            after_window_update: true,
1047        })
1048    }
1049
1050    fn notify_model(&mut self, model_id: usize) {
1051        if self.pending_notifications.insert(model_id) {
1052            self.pending_effects
1053                .push_back(Effect::ModelNotification { model_id });
1054        }
1055    }
1056
1057    fn notify_view(&mut self, window_id: usize, view_id: usize) {
1058        if self.pending_notifications.insert(view_id) {
1059            self.pending_effects
1060                .push_back(Effect::ViewNotification { window_id, view_id });
1061        }
1062    }
1063
1064    fn notify_global(&mut self, type_id: TypeId) {
1065        if self.pending_global_notifications.insert(type_id) {
1066            self.pending_effects
1067                .push_back(Effect::GlobalNotification { type_id });
1068        }
1069    }
1070
1071    pub fn all_action_names<'a>(&'a self) -> impl Iterator<Item = &'static str> + 'a {
1072        self.action_deserializers.keys().copied()
1073    }
1074
1075    pub fn is_action_available(&self, action: &dyn Action) -> bool {
1076        let mut available_in_window = false;
1077        let action_id = action.id();
1078        if let Some(window_id) = self.platform.main_window_id() {
1079            available_in_window = self
1080                .read_window(window_id, |cx| {
1081                    if let Some(focused_view_id) = cx.focused_view_id() {
1082                        for view_id in cx.ancestors(focused_view_id) {
1083                            if let Some(view_metadata) =
1084                                cx.views_metadata.get(&(window_id, view_id))
1085                            {
1086                                if let Some(actions) = cx.actions.get(&view_metadata.type_id) {
1087                                    if actions.contains_key(&action_id) {
1088                                        return true;
1089                                    }
1090                                }
1091                            }
1092                        }
1093                    }
1094                    false
1095                })
1096                .unwrap_or(false);
1097        }
1098        available_in_window || self.global_actions.contains_key(&action_id)
1099    }
1100
1101    fn actions_mut(
1102        &mut self,
1103        capture_phase: bool,
1104    ) -> &mut HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>> {
1105        if capture_phase {
1106            &mut self.capture_actions
1107        } else {
1108            &mut self.actions
1109        }
1110    }
1111
1112    fn dispatch_global_action_any(&mut self, action: &dyn Action) -> bool {
1113        self.update(|this| {
1114            if let Some((name, mut handler)) = this.global_actions.remove_entry(&action.id()) {
1115                handler(action, this);
1116                this.global_actions.insert(name, handler);
1117                true
1118            } else {
1119                false
1120            }
1121        })
1122    }
1123
1124    pub fn add_bindings<T: IntoIterator<Item = Binding>>(&mut self, bindings: T) {
1125        self.keystroke_matcher.add_bindings(bindings);
1126    }
1127
1128    pub fn clear_bindings(&mut self) {
1129        self.keystroke_matcher.clear_bindings();
1130    }
1131
1132    pub fn default_global<T: 'static + Default>(&mut self) -> &T {
1133        let type_id = TypeId::of::<T>();
1134        self.update(|this| {
1135            if let Entry::Vacant(entry) = this.globals.entry(type_id) {
1136                entry.insert(Box::new(T::default()));
1137                this.notify_global(type_id);
1138            }
1139        });
1140        self.globals.get(&type_id).unwrap().downcast_ref().unwrap()
1141    }
1142
1143    pub fn set_global<T: 'static>(&mut self, state: T) {
1144        self.update(|this| {
1145            let type_id = TypeId::of::<T>();
1146            this.globals.insert(type_id, Box::new(state));
1147            this.notify_global(type_id);
1148        });
1149    }
1150
1151    pub fn update_default_global<T, F, U>(&mut self, update: F) -> U
1152    where
1153        T: 'static + Default,
1154        F: FnOnce(&mut T, &mut AppContext) -> U,
1155    {
1156        self.update(|mut this| {
1157            Self::update_default_global_internal(&mut this, |global, cx| update(global, cx))
1158        })
1159    }
1160
1161    fn update_default_global_internal<C, T, F, U>(this: &mut C, update: F) -> U
1162    where
1163        C: DerefMut<Target = AppContext>,
1164        T: 'static + Default,
1165        F: FnOnce(&mut T, &mut C) -> U,
1166    {
1167        let type_id = TypeId::of::<T>();
1168        let mut state = this
1169            .globals
1170            .remove(&type_id)
1171            .unwrap_or_else(|| Box::new(T::default()));
1172        let result = update(state.downcast_mut().unwrap(), this);
1173        this.globals.insert(type_id, state);
1174        this.notify_global(type_id);
1175        result
1176    }
1177
1178    pub fn update_global<T, F, U>(&mut self, update: F) -> U
1179    where
1180        T: 'static,
1181        F: FnOnce(&mut T, &mut AppContext) -> U,
1182    {
1183        self.update(|mut this| {
1184            Self::update_global_internal(&mut this, |global, cx| update(global, cx))
1185        })
1186    }
1187
1188    fn update_global_internal<C, T, F, U>(this: &mut C, update: F) -> U
1189    where
1190        C: DerefMut<Target = AppContext>,
1191        T: 'static,
1192        F: FnOnce(&mut T, &mut C) -> U,
1193    {
1194        let type_id = TypeId::of::<T>();
1195        if let Some(mut state) = this.globals.remove(&type_id) {
1196            let result = update(state.downcast_mut().unwrap(), this);
1197            this.globals.insert(type_id, state);
1198            this.notify_global(type_id);
1199            result
1200        } else {
1201            panic!("no global added for {}", std::any::type_name::<T>());
1202        }
1203    }
1204
1205    pub fn clear_globals(&mut self) {
1206        self.globals.clear();
1207    }
1208
1209    pub fn remove_global<T: 'static>(&mut self) -> T {
1210        *self
1211            .globals
1212            .remove(&TypeId::of::<T>())
1213            .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<T>()))
1214            .downcast()
1215            .unwrap()
1216    }
1217
1218    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
1219    where
1220        T: Entity,
1221        F: FnOnce(&mut ModelContext<T>) -> T,
1222    {
1223        self.update(|this| {
1224            let model_id = post_inc(&mut this.next_entity_id);
1225            let handle = ModelHandle::new(model_id, &this.ref_counts);
1226            let mut cx = ModelContext::new(this, model_id);
1227            let model = build_model(&mut cx);
1228            this.models.insert(model_id, Box::new(model));
1229            handle
1230        })
1231    }
1232
1233    pub fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
1234        if let Some(model) = self.models.get(&handle.model_id) {
1235            model
1236                .as_any()
1237                .downcast_ref()
1238                .expect("downcast is type safe")
1239        } else {
1240            panic!("circular model reference");
1241        }
1242    }
1243
1244    fn update_model<T: Entity, V>(
1245        &mut self,
1246        handle: &ModelHandle<T>,
1247        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
1248    ) -> V {
1249        if let Some(mut model) = self.models.remove(&handle.model_id) {
1250            self.update(|this| {
1251                let mut cx = ModelContext::new(this, handle.model_id);
1252                let result = update(
1253                    model
1254                        .as_any_mut()
1255                        .downcast_mut()
1256                        .expect("downcast is type safe"),
1257                    &mut cx,
1258                );
1259                this.models.insert(handle.model_id, model);
1260                result
1261            })
1262        } else {
1263            panic!("circular model update");
1264        }
1265    }
1266
1267    fn upgrade_model_handle<T: Entity>(
1268        &self,
1269        handle: &WeakModelHandle<T>,
1270    ) -> Option<ModelHandle<T>> {
1271        if self.ref_counts.lock().is_entity_alive(handle.model_id) {
1272            Some(ModelHandle::new(handle.model_id, &self.ref_counts))
1273        } else {
1274            None
1275        }
1276    }
1277
1278    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
1279        self.ref_counts.lock().is_entity_alive(handle.model_id)
1280    }
1281
1282    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
1283        if self.ref_counts.lock().is_entity_alive(handle.model_id) {
1284            Some(AnyModelHandle::new(
1285                handle.model_id,
1286                handle.model_type,
1287                self.ref_counts.clone(),
1288            ))
1289        } else {
1290            None
1291        }
1292    }
1293
1294    pub fn add_window<V, F>(
1295        &mut self,
1296        window_options: WindowOptions,
1297        build_root_view: F,
1298    ) -> (usize, ViewHandle<V>)
1299    where
1300        V: View,
1301        F: FnOnce(&mut ViewContext<V>) -> V,
1302    {
1303        self.update(|this| {
1304            let window_id = post_inc(&mut this.next_window_id);
1305            let platform_window =
1306                this.platform
1307                    .open_window(window_id, window_options, this.foreground.clone());
1308            let window = this.build_window(window_id, platform_window, build_root_view);
1309            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1310            this.windows.insert(window_id, window);
1311            (window_id, root_view)
1312        })
1313    }
1314
1315    pub fn add_status_bar_item<V, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<V>)
1316    where
1317        V: View,
1318        F: FnOnce(&mut ViewContext<V>) -> V,
1319    {
1320        self.update(|this| {
1321            let window_id = post_inc(&mut this.next_window_id);
1322            let platform_window = this.platform.add_status_item(window_id);
1323            let window = this.build_window(window_id, platform_window, build_root_view);
1324            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1325
1326            this.windows.insert(window_id, window);
1327            this.update_window(window_id, |cx| {
1328                root_view.update(cx, |view, cx| view.focus_in(cx.handle().into_any(), cx))
1329            });
1330
1331            (window_id, root_view)
1332        })
1333    }
1334
1335    pub fn build_window<V, F>(
1336        &mut self,
1337        window_id: usize,
1338        mut platform_window: Box<dyn platform::Window>,
1339        build_root_view: F,
1340    ) -> Window
1341    where
1342        V: View,
1343        F: FnOnce(&mut ViewContext<V>) -> V,
1344    {
1345        {
1346            let mut app = self.upgrade();
1347
1348            platform_window.on_event(Box::new(move |event| {
1349                app.update_window(window_id, |cx| {
1350                    if let Event::KeyDown(KeyDownEvent { keystroke, .. }) = &event {
1351                        if cx.dispatch_keystroke(keystroke) {
1352                            return true;
1353                        }
1354                    }
1355
1356                    cx.dispatch_event(event, false)
1357                })
1358                .unwrap_or(false)
1359            }));
1360        }
1361
1362        {
1363            let mut app = self.upgrade();
1364            platform_window.on_active_status_change(Box::new(move |is_active| {
1365                app.update(|cx| cx.window_changed_active_status(window_id, is_active))
1366            }));
1367        }
1368
1369        {
1370            let mut app = self.upgrade();
1371            platform_window.on_resize(Box::new(move || {
1372                app.update(|cx| cx.window_was_resized(window_id))
1373            }));
1374        }
1375
1376        {
1377            let mut app = self.upgrade();
1378            platform_window.on_moved(Box::new(move || {
1379                app.update(|cx| cx.window_was_moved(window_id))
1380            }));
1381        }
1382
1383        {
1384            let mut app = self.upgrade();
1385            platform_window.on_fullscreen(Box::new(move |is_fullscreen| {
1386                app.update(|cx| cx.window_was_fullscreen_changed(window_id, is_fullscreen))
1387            }));
1388        }
1389
1390        {
1391            let mut app = self.upgrade();
1392            platform_window.on_close(Box::new(move || {
1393                app.update(|cx| cx.update_window(window_id, |cx| cx.remove_window()));
1394            }));
1395        }
1396
1397        {
1398            let mut app = self.upgrade();
1399            platform_window
1400                .on_appearance_changed(Box::new(move || app.update(|cx| cx.refresh_windows())));
1401        }
1402
1403        platform_window.set_input_handler(Box::new(WindowInputHandler {
1404            app: self.upgrade().0,
1405            window_id,
1406        }));
1407
1408        let mut window = Window::new(window_id, platform_window, self, build_root_view);
1409        let mut cx = WindowContext::mutable(self, &mut window, window_id);
1410        cx.layout(false).expect("initial layout should not error");
1411        let scene = cx.paint().expect("initial paint should not error");
1412        window.platform_window.present_scene(scene);
1413        window
1414    }
1415
1416    pub fn replace_root_view<V, F>(
1417        &mut self,
1418        window_id: usize,
1419        build_root_view: F,
1420    ) -> Option<ViewHandle<V>>
1421    where
1422        V: View,
1423        F: FnOnce(&mut ViewContext<V>) -> V,
1424    {
1425        self.update_window(window_id, |cx| cx.replace_root_view(build_root_view))
1426    }
1427
1428    pub fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
1429        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
1430            view.as_any().downcast_ref().expect("downcast is type safe")
1431        } else {
1432            panic!("circular view reference for type {}", type_name::<T>());
1433        }
1434    }
1435
1436    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
1437        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
1438            Some(ViewHandle::new(
1439                handle.window_id,
1440                handle.view_id,
1441                &self.ref_counts,
1442            ))
1443        } else {
1444            None
1445        }
1446    }
1447
1448    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
1449        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
1450            Some(AnyViewHandle::new(
1451                handle.window_id,
1452                handle.view_id,
1453                handle.view_type,
1454                self.ref_counts.clone(),
1455            ))
1456        } else {
1457            None
1458        }
1459    }
1460
1461    fn remove_dropped_entities(&mut self) {
1462        loop {
1463            let (dropped_models, dropped_views, dropped_element_states) =
1464                self.ref_counts.lock().take_dropped();
1465            if dropped_models.is_empty()
1466                && dropped_views.is_empty()
1467                && dropped_element_states.is_empty()
1468            {
1469                break;
1470            }
1471
1472            for model_id in dropped_models {
1473                self.subscriptions.remove(model_id);
1474                self.observations.remove(model_id);
1475                let mut model = self.models.remove(&model_id).unwrap();
1476                model.release(self);
1477                self.pending_effects
1478                    .push_back(Effect::ModelRelease { model_id, model });
1479            }
1480
1481            for (window_id, view_id) in dropped_views {
1482                self.subscriptions.remove(view_id);
1483                self.observations.remove(view_id);
1484                self.views_metadata.remove(&(window_id, view_id));
1485                let mut view = self.views.remove(&(window_id, view_id)).unwrap();
1486                view.release(self);
1487                if let Some(window) = self.windows.get_mut(&window_id) {
1488                    window.parents.remove(&view_id);
1489                    window
1490                        .invalidation
1491                        .get_or_insert_with(Default::default)
1492                        .removed
1493                        .push(view_id);
1494                }
1495
1496                self.pending_effects
1497                    .push_back(Effect::ViewRelease { view_id, view });
1498            }
1499
1500            for key in dropped_element_states {
1501                self.element_states.remove(&key);
1502            }
1503        }
1504    }
1505
1506    fn flush_effects(&mut self) {
1507        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1508        let mut after_window_update_callbacks = Vec::new();
1509
1510        if !self.flushing_effects && self.pending_flushes == 0 {
1511            self.flushing_effects = true;
1512
1513            let mut refreshing = false;
1514            let mut updated_windows = HashSet::default();
1515            let mut focus_effects = HashMap::<usize, FocusEffect>::default();
1516            loop {
1517                self.remove_dropped_entities();
1518                if let Some(effect) = self.pending_effects.pop_front() {
1519                    match effect {
1520                        Effect::Subscription {
1521                            entity_id,
1522                            subscription_id,
1523                            callback,
1524                        } => self
1525                            .subscriptions
1526                            .add_callback(entity_id, subscription_id, callback),
1527
1528                        Effect::Event { entity_id, payload } => {
1529                            let mut subscriptions = self.subscriptions.clone();
1530                            subscriptions
1531                                .emit(entity_id, |callback| callback(payload.as_ref(), self))
1532                        }
1533
1534                        Effect::GlobalSubscription {
1535                            type_id,
1536                            subscription_id,
1537                            callback,
1538                        } => self.global_subscriptions.add_callback(
1539                            type_id,
1540                            subscription_id,
1541                            callback,
1542                        ),
1543
1544                        Effect::GlobalEvent { payload } => self.emit_global_event(payload),
1545
1546                        Effect::Observation {
1547                            entity_id,
1548                            subscription_id,
1549                            callback,
1550                        } => self
1551                            .observations
1552                            .add_callback(entity_id, subscription_id, callback),
1553
1554                        Effect::ModelNotification { model_id } => {
1555                            let mut observations = self.observations.clone();
1556                            observations.emit(model_id, |callback| callback(self));
1557                        }
1558
1559                        Effect::ViewNotification { window_id, view_id } => {
1560                            self.handle_view_notification_effect(window_id, view_id)
1561                        }
1562
1563                        Effect::GlobalNotification { type_id } => {
1564                            let mut subscriptions = self.global_observations.clone();
1565                            subscriptions.emit(type_id, |callback| {
1566                                callback(self);
1567                                true
1568                            });
1569                        }
1570
1571                        Effect::Deferred {
1572                            callback,
1573                            after_window_update,
1574                        } => {
1575                            if after_window_update {
1576                                after_window_update_callbacks.push(callback);
1577                            } else {
1578                                callback(self)
1579                            }
1580                        }
1581
1582                        Effect::ModelRelease { model_id, model } => {
1583                            self.handle_entity_release_effect(model_id, model.as_any())
1584                        }
1585
1586                        Effect::ViewRelease { view_id, view } => {
1587                            self.handle_entity_release_effect(view_id, view.as_any())
1588                        }
1589
1590                        Effect::Focus(mut effect) => {
1591                            if focus_effects
1592                                .get(&effect.window_id())
1593                                .map_or(false, |prev_effect| prev_effect.is_forced())
1594                            {
1595                                effect.force();
1596                            }
1597
1598                            focus_effects.insert(effect.window_id(), effect);
1599                        }
1600
1601                        Effect::FocusObservation {
1602                            view_id,
1603                            subscription_id,
1604                            callback,
1605                        } => {
1606                            self.focus_observations.add_callback(
1607                                view_id,
1608                                subscription_id,
1609                                callback,
1610                            );
1611                        }
1612
1613                        Effect::ResizeWindow { window_id } => {
1614                            if let Some(window) = self.windows.get_mut(&window_id) {
1615                                window
1616                                    .invalidation
1617                                    .get_or_insert(WindowInvalidation::default());
1618                            }
1619                            self.handle_window_moved(window_id);
1620                        }
1621
1622                        Effect::MoveWindow { window_id } => {
1623                            self.handle_window_moved(window_id);
1624                        }
1625
1626                        Effect::WindowActivationObservation {
1627                            window_id,
1628                            subscription_id,
1629                            callback,
1630                        } => self.window_activation_observations.add_callback(
1631                            window_id,
1632                            subscription_id,
1633                            callback,
1634                        ),
1635
1636                        Effect::ActivateWindow {
1637                            window_id,
1638                            is_active,
1639                        } => {
1640                            if self.handle_window_activation_effect(window_id, is_active)
1641                                && is_active
1642                            {
1643                                focus_effects
1644                                    .entry(window_id)
1645                                    .or_insert_with(|| FocusEffect::View {
1646                                        window_id,
1647                                        view_id: self
1648                                            .read_window(window_id, |cx| cx.focused_view_id())
1649                                            .flatten(),
1650                                        is_forced: true,
1651                                    })
1652                                    .force();
1653                            }
1654                        }
1655
1656                        Effect::WindowFullscreenObservation {
1657                            window_id,
1658                            subscription_id,
1659                            callback,
1660                        } => self.window_fullscreen_observations.add_callback(
1661                            window_id,
1662                            subscription_id,
1663                            callback,
1664                        ),
1665
1666                        Effect::FullscreenWindow {
1667                            window_id,
1668                            is_fullscreen,
1669                        } => self.handle_fullscreen_effect(window_id, is_fullscreen),
1670
1671                        Effect::WindowBoundsObservation {
1672                            window_id,
1673                            subscription_id,
1674                            callback,
1675                        } => self.window_bounds_observations.add_callback(
1676                            window_id,
1677                            subscription_id,
1678                            callback,
1679                        ),
1680
1681                        Effect::RefreshWindows => {
1682                            refreshing = true;
1683                        }
1684
1685                        Effect::ActionDispatchNotification { action_id } => {
1686                            self.handle_action_dispatch_notification_effect(action_id)
1687                        }
1688                        Effect::WindowShouldCloseSubscription {
1689                            window_id,
1690                            callback,
1691                        } => {
1692                            self.handle_window_should_close_subscription_effect(window_id, callback)
1693                        }
1694                        Effect::Keystroke {
1695                            window_id,
1696                            keystroke,
1697                            handled_by,
1698                            result,
1699                        } => self.handle_keystroke_effect(window_id, keystroke, handled_by, result),
1700                        Effect::ActiveLabeledTasksChanged => {
1701                            self.handle_active_labeled_tasks_changed_effect()
1702                        }
1703                        Effect::ActiveLabeledTasksObservation {
1704                            subscription_id,
1705                            callback,
1706                        } => self.active_labeled_task_observations.add_callback(
1707                            (),
1708                            subscription_id,
1709                            callback,
1710                        ),
1711                    }
1712                    self.pending_notifications.clear();
1713                } else {
1714                    for window_id in self.windows.keys().cloned().collect::<Vec<_>>() {
1715                        self.update_window(window_id, |cx| {
1716                            let invalidation = if refreshing {
1717                                let mut invalidation =
1718                                    cx.window.invalidation.take().unwrap_or_default();
1719                                invalidation
1720                                    .updated
1721                                    .extend(cx.window.rendered_views.keys().copied());
1722                                Some(invalidation)
1723                            } else {
1724                                cx.window.invalidation.take()
1725                            };
1726
1727                            if let Some(invalidation) = invalidation {
1728                                let appearance = cx.window.platform_window.appearance();
1729                                cx.invalidate(invalidation, appearance);
1730                                if let Some(old_parents) = cx.layout(refreshing).log_err() {
1731                                    updated_windows.insert(window_id);
1732
1733                                    if let Some(focused_view_id) = cx.focused_view_id() {
1734                                        let old_ancestors = std::iter::successors(
1735                                            Some(focused_view_id),
1736                                            |&view_id| old_parents.get(&view_id).copied(),
1737                                        )
1738                                        .collect::<HashSet<_>>();
1739                                        let new_ancestors =
1740                                            cx.ancestors(focused_view_id).collect::<HashSet<_>>();
1741
1742                                        // Notify the old ancestors of the focused view when they don't contain it anymore.
1743                                        for old_ancestor in old_ancestors.iter().copied() {
1744                                            if !new_ancestors.contains(&old_ancestor) {
1745                                                if let Some(mut view) =
1746                                                    cx.views.remove(&(window_id, old_ancestor))
1747                                                {
1748                                                    view.focus_out(
1749                                                        focused_view_id,
1750                                                        cx,
1751                                                        old_ancestor,
1752                                                    );
1753                                                    cx.views
1754                                                        .insert((window_id, old_ancestor), view);
1755                                                }
1756                                            }
1757                                        }
1758
1759                                        // Notify the new ancestors of the focused view if they contain it now.
1760                                        for new_ancestor in new_ancestors.iter().copied() {
1761                                            if !old_ancestors.contains(&new_ancestor) {
1762                                                if let Some(mut view) =
1763                                                    cx.views.remove(&(window_id, new_ancestor))
1764                                                {
1765                                                    view.focus_in(
1766                                                        focused_view_id,
1767                                                        cx,
1768                                                        new_ancestor,
1769                                                    );
1770                                                    cx.views
1771                                                        .insert((window_id, new_ancestor), view);
1772                                                }
1773                                            }
1774                                        }
1775
1776                                        // When the previously-focused view has been dropped and
1777                                        // there isn't any pending focus, focus the root view.
1778                                        let root_view_id = cx.window.root_view().id();
1779                                        if focused_view_id != root_view_id
1780                                            && !cx.views.contains_key(&(window_id, focused_view_id))
1781                                            && !focus_effects.contains_key(&window_id)
1782                                        {
1783                                            focus_effects.insert(
1784                                                window_id,
1785                                                FocusEffect::View {
1786                                                    window_id,
1787                                                    view_id: Some(root_view_id),
1788                                                    is_forced: false,
1789                                                },
1790                                            );
1791                                        }
1792                                    }
1793                                }
1794                            }
1795                        });
1796                    }
1797
1798                    for (_, effect) in focus_effects.drain() {
1799                        self.handle_focus_effect(effect);
1800                    }
1801
1802                    if self.pending_effects.is_empty() {
1803                        for callback in after_window_update_callbacks.drain(..) {
1804                            callback(self);
1805                        }
1806
1807                        for window_id in updated_windows.drain() {
1808                            self.update_window(window_id, |cx| {
1809                                if let Some(scene) = cx.paint().log_err() {
1810                                    cx.window.platform_window.present_scene(scene);
1811                                }
1812                            });
1813                        }
1814
1815                        if self.pending_effects.is_empty() {
1816                            self.flushing_effects = false;
1817                            self.pending_notifications.clear();
1818                            self.pending_global_notifications.clear();
1819                            break;
1820                        }
1821                    }
1822
1823                    refreshing = false;
1824                }
1825            }
1826        }
1827    }
1828
1829    fn window_was_resized(&mut self, window_id: usize) {
1830        self.pending_effects
1831            .push_back(Effect::ResizeWindow { window_id });
1832    }
1833
1834    fn window_was_moved(&mut self, window_id: usize) {
1835        self.pending_effects
1836            .push_back(Effect::MoveWindow { window_id });
1837    }
1838
1839    fn window_was_fullscreen_changed(&mut self, window_id: usize, is_fullscreen: bool) {
1840        self.pending_effects.push_back(Effect::FullscreenWindow {
1841            window_id,
1842            is_fullscreen,
1843        });
1844    }
1845
1846    fn window_changed_active_status(&mut self, window_id: usize, is_active: bool) {
1847        self.pending_effects.push_back(Effect::ActivateWindow {
1848            window_id,
1849            is_active,
1850        });
1851    }
1852
1853    fn keystroke(
1854        &mut self,
1855        window_id: usize,
1856        keystroke: Keystroke,
1857        handled_by: Option<Box<dyn Action>>,
1858        result: MatchResult,
1859    ) {
1860        self.pending_effects.push_back(Effect::Keystroke {
1861            window_id,
1862            keystroke,
1863            handled_by,
1864            result,
1865        });
1866    }
1867
1868    pub fn refresh_windows(&mut self) {
1869        self.pending_effects.push_back(Effect::RefreshWindows);
1870    }
1871
1872    fn emit_global_event(&mut self, payload: Box<dyn Any>) {
1873        let type_id = (&*payload).type_id();
1874
1875        let mut subscriptions = self.global_subscriptions.clone();
1876        subscriptions.emit(type_id, |callback| {
1877            callback(payload.as_ref(), self);
1878            true //Always alive
1879        });
1880    }
1881
1882    fn handle_view_notification_effect(
1883        &mut self,
1884        observed_window_id: usize,
1885        observed_view_id: usize,
1886    ) {
1887        let view_key = (observed_window_id, observed_view_id);
1888        if let Some((view, mut view_metadata)) = self
1889            .views
1890            .remove(&view_key)
1891            .zip(self.views_metadata.remove(&view_key))
1892        {
1893            if let Some(window) = self.windows.get_mut(&observed_window_id) {
1894                window
1895                    .invalidation
1896                    .get_or_insert_with(Default::default)
1897                    .updated
1898                    .insert(observed_view_id);
1899            }
1900
1901            view.update_keymap_context(&mut view_metadata.keymap_context, self);
1902            self.views.insert(view_key, view);
1903            self.views_metadata.insert(view_key, view_metadata);
1904
1905            let mut observations = self.observations.clone();
1906            observations.emit(observed_view_id, |callback| callback(self));
1907        }
1908    }
1909
1910    fn handle_entity_release_effect(&mut self, entity_id: usize, entity: &dyn Any) {
1911        self.release_observations
1912            .clone()
1913            .emit(entity_id, |callback| {
1914                callback(entity, self);
1915                // Release observations happen one time. So clear the callback by returning false
1916                false
1917            })
1918    }
1919
1920    fn handle_fullscreen_effect(&mut self, window_id: usize, is_fullscreen: bool) {
1921        self.update_window(window_id, |cx| {
1922            cx.window.is_fullscreen = is_fullscreen;
1923
1924            let mut fullscreen_observations = cx.window_fullscreen_observations.clone();
1925            fullscreen_observations.emit(window_id, |callback| callback(is_fullscreen, cx));
1926
1927            if let Some(uuid) = cx.window_display_uuid() {
1928                let bounds = cx.window_bounds();
1929                let mut bounds_observations = cx.window_bounds_observations.clone();
1930                bounds_observations.emit(window_id, |callback| callback(bounds, uuid, cx));
1931            }
1932
1933            Some(())
1934        });
1935    }
1936
1937    fn handle_keystroke_effect(
1938        &mut self,
1939        window_id: usize,
1940        keystroke: Keystroke,
1941        handled_by: Option<Box<dyn Action>>,
1942        result: MatchResult,
1943    ) {
1944        self.update_window(window_id, |cx| {
1945            let mut observations = cx.keystroke_observations.clone();
1946            observations.emit(window_id, move |callback| {
1947                callback(&keystroke, &result, handled_by.as_ref(), cx)
1948            });
1949        });
1950    }
1951
1952    fn handle_window_activation_effect(&mut self, window_id: usize, active: bool) -> bool {
1953        self.update_window(window_id, |cx| {
1954            if cx.window.is_active == active {
1955                return false;
1956            }
1957            cx.window.is_active = active;
1958
1959            let mut observations = cx.window_activation_observations.clone();
1960            observations.emit(window_id, |callback| callback(active, cx));
1961            true
1962        })
1963        .unwrap_or(false)
1964    }
1965
1966    fn handle_focus_effect(&mut self, effect: FocusEffect) {
1967        let window_id = effect.window_id();
1968        self.update_window(window_id, |cx| {
1969            // Ensure the newly-focused view still exists, otherwise focus
1970            // the root view instead.
1971            let focused_id = match effect {
1972                FocusEffect::View { view_id, .. } => {
1973                    if let Some(view_id) = view_id {
1974                        if cx.views.contains_key(&(window_id, view_id)) {
1975                            Some(view_id)
1976                        } else {
1977                            Some(cx.root_view().id())
1978                        }
1979                    } else {
1980                        None
1981                    }
1982                }
1983                FocusEffect::ViewParent { view_id, .. } => Some(
1984                    cx.window
1985                        .parents
1986                        .get(&view_id)
1987                        .copied()
1988                        .unwrap_or(cx.root_view().id()),
1989                ),
1990            };
1991
1992            let focus_changed = cx.window.focused_view_id != focused_id;
1993            let blurred_id = cx.window.focused_view_id;
1994            cx.window.focused_view_id = focused_id;
1995
1996            if focus_changed {
1997                if let Some(blurred_id) = blurred_id {
1998                    for view_id in cx.ancestors(blurred_id).collect::<Vec<_>>() {
1999                        if let Some(mut view) = cx.views.remove(&(window_id, view_id)) {
2000                            view.focus_out(blurred_id, cx, view_id);
2001                            cx.views.insert((window_id, view_id), view);
2002                        }
2003                    }
2004
2005                    let mut subscriptions = cx.focus_observations.clone();
2006                    subscriptions.emit(blurred_id, |callback| callback(false, cx));
2007                }
2008            }
2009
2010            if focus_changed || effect.is_forced() {
2011                if let Some(focused_id) = focused_id {
2012                    for view_id in cx.ancestors(focused_id).collect::<Vec<_>>() {
2013                        if let Some(mut view) = cx.views.remove(&(window_id, view_id)) {
2014                            view.focus_in(focused_id, cx, view_id);
2015                            cx.views.insert((window_id, view_id), view);
2016                        }
2017                    }
2018
2019                    let mut subscriptions = cx.focus_observations.clone();
2020                    subscriptions.emit(focused_id, |callback| callback(true, cx));
2021                }
2022            }
2023        });
2024    }
2025
2026    fn handle_action_dispatch_notification_effect(&mut self, action_id: TypeId) {
2027        self.action_dispatch_observations
2028            .clone()
2029            .emit((), |callback| {
2030                callback(action_id, self);
2031                true
2032            });
2033    }
2034
2035    fn handle_window_should_close_subscription_effect(
2036        &mut self,
2037        window_id: usize,
2038        mut callback: WindowShouldCloseSubscriptionCallback,
2039    ) {
2040        let mut app = self.upgrade();
2041        if let Some(window) = self.windows.get_mut(&window_id) {
2042            window
2043                .platform_window
2044                .on_should_close(Box::new(move || app.update(|cx| callback(cx))))
2045        }
2046    }
2047
2048    fn handle_window_moved(&mut self, window_id: usize) {
2049        self.update_window(window_id, |cx| {
2050            if let Some(display) = cx.window_display_uuid() {
2051                let bounds = cx.window_bounds();
2052                cx.window_bounds_observations
2053                    .clone()
2054                    .emit(window_id, move |callback| {
2055                        callback(bounds, display, cx);
2056                        true
2057                    });
2058            }
2059        });
2060    }
2061
2062    fn handle_active_labeled_tasks_changed_effect(&mut self) {
2063        self.active_labeled_task_observations
2064            .clone()
2065            .emit((), move |callback| {
2066                callback(self);
2067                true
2068            });
2069    }
2070
2071    pub fn focus(&mut self, window_id: usize, view_id: Option<usize>) {
2072        self.pending_effects
2073            .push_back(Effect::Focus(FocusEffect::View {
2074                window_id,
2075                view_id,
2076                is_forced: false,
2077            }));
2078    }
2079
2080    fn spawn_internal<F, Fut, T>(&mut self, task_name: Option<&'static str>, f: F) -> Task<T>
2081    where
2082        F: FnOnce(AsyncAppContext) -> Fut,
2083        Fut: 'static + Future<Output = T>,
2084        T: 'static,
2085    {
2086        let label_id = task_name.map(|task_name| {
2087            let id = post_inc(&mut self.next_labeled_task_id);
2088            self.active_labeled_tasks.insert(id, task_name);
2089            self.pending_effects
2090                .push_back(Effect::ActiveLabeledTasksChanged);
2091            id
2092        });
2093
2094        let future = f(self.to_async());
2095        let cx = self.to_async();
2096        self.foreground.spawn(async move {
2097            let result = future.await;
2098            let mut cx = cx.0.borrow_mut();
2099
2100            if let Some(completed_label_id) = label_id {
2101                cx.active_labeled_tasks.remove(&completed_label_id);
2102                cx.pending_effects
2103                    .push_back(Effect::ActiveLabeledTasksChanged);
2104            }
2105            cx.flush_effects();
2106            result
2107        })
2108    }
2109
2110    pub fn spawn_labeled<F, Fut, T>(&mut self, task_name: &'static str, f: F) -> Task<T>
2111    where
2112        F: FnOnce(AsyncAppContext) -> Fut,
2113        Fut: 'static + Future<Output = T>,
2114        T: 'static,
2115    {
2116        self.spawn_internal(Some(task_name), f)
2117    }
2118
2119    pub fn spawn<F, Fut, T>(&mut self, f: F) -> Task<T>
2120    where
2121        F: FnOnce(AsyncAppContext) -> Fut,
2122        Fut: 'static + Future<Output = T>,
2123        T: 'static,
2124    {
2125        self.spawn_internal(None, f)
2126    }
2127
2128    pub fn to_async(&self) -> AsyncAppContext {
2129        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
2130    }
2131
2132    pub fn write_to_clipboard(&self, item: ClipboardItem) {
2133        self.platform.write_to_clipboard(item);
2134    }
2135
2136    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
2137        self.platform.read_from_clipboard()
2138    }
2139
2140    #[cfg(any(test, feature = "test-support"))]
2141    pub fn leak_detector(&self) -> Arc<Mutex<LeakDetector>> {
2142        self.ref_counts.lock().leak_detector.clone()
2143    }
2144}
2145
2146impl BorrowAppContext for AppContext {
2147    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
2148        f(self)
2149    }
2150
2151    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
2152        f(self)
2153    }
2154}
2155
2156#[derive(Debug)]
2157pub enum ParentId {
2158    View(usize),
2159    Root,
2160}
2161
2162struct ViewMetadata {
2163    type_id: TypeId,
2164    keymap_context: KeymapContext,
2165}
2166
2167#[derive(Default, Clone)]
2168pub struct WindowInvalidation {
2169    pub updated: HashSet<usize>,
2170    pub removed: Vec<usize>,
2171}
2172
2173#[derive(Debug)]
2174pub enum FocusEffect {
2175    View {
2176        window_id: usize,
2177        view_id: Option<usize>,
2178        is_forced: bool,
2179    },
2180    ViewParent {
2181        window_id: usize,
2182        view_id: usize,
2183        is_forced: bool,
2184    },
2185}
2186
2187impl FocusEffect {
2188    fn window_id(&self) -> usize {
2189        match self {
2190            FocusEffect::View { window_id, .. } => *window_id,
2191            FocusEffect::ViewParent { window_id, .. } => *window_id,
2192        }
2193    }
2194
2195    fn is_forced(&self) -> bool {
2196        match self {
2197            FocusEffect::View { is_forced, .. } => *is_forced,
2198            FocusEffect::ViewParent { is_forced, .. } => *is_forced,
2199        }
2200    }
2201
2202    fn force(&mut self) {
2203        match self {
2204            FocusEffect::View { is_forced, .. } => *is_forced = true,
2205            FocusEffect::ViewParent { is_forced, .. } => *is_forced = true,
2206        }
2207    }
2208}
2209
2210pub enum Effect {
2211    Subscription {
2212        entity_id: usize,
2213        subscription_id: usize,
2214        callback: SubscriptionCallback,
2215    },
2216    Event {
2217        entity_id: usize,
2218        payload: Box<dyn Any>,
2219    },
2220    GlobalSubscription {
2221        type_id: TypeId,
2222        subscription_id: usize,
2223        callback: GlobalSubscriptionCallback,
2224    },
2225    GlobalEvent {
2226        payload: Box<dyn Any>,
2227    },
2228    Observation {
2229        entity_id: usize,
2230        subscription_id: usize,
2231        callback: ObservationCallback,
2232    },
2233    ModelNotification {
2234        model_id: usize,
2235    },
2236    ViewNotification {
2237        window_id: usize,
2238        view_id: usize,
2239    },
2240    Deferred {
2241        callback: Box<dyn FnOnce(&mut AppContext)>,
2242        after_window_update: bool,
2243    },
2244    GlobalNotification {
2245        type_id: TypeId,
2246    },
2247    ModelRelease {
2248        model_id: usize,
2249        model: Box<dyn AnyModel>,
2250    },
2251    ViewRelease {
2252        view_id: usize,
2253        view: Box<dyn AnyView>,
2254    },
2255    Focus(FocusEffect),
2256    FocusObservation {
2257        view_id: usize,
2258        subscription_id: usize,
2259        callback: FocusObservationCallback,
2260    },
2261    ResizeWindow {
2262        window_id: usize,
2263    },
2264    MoveWindow {
2265        window_id: usize,
2266    },
2267    ActivateWindow {
2268        window_id: usize,
2269        is_active: bool,
2270    },
2271    WindowActivationObservation {
2272        window_id: usize,
2273        subscription_id: usize,
2274        callback: WindowActivationCallback,
2275    },
2276    FullscreenWindow {
2277        window_id: usize,
2278        is_fullscreen: bool,
2279    },
2280    WindowFullscreenObservation {
2281        window_id: usize,
2282        subscription_id: usize,
2283        callback: WindowFullscreenCallback,
2284    },
2285    WindowBoundsObservation {
2286        window_id: usize,
2287        subscription_id: usize,
2288        callback: WindowBoundsCallback,
2289    },
2290    Keystroke {
2291        window_id: usize,
2292        keystroke: Keystroke,
2293        handled_by: Option<Box<dyn Action>>,
2294        result: MatchResult,
2295    },
2296    RefreshWindows,
2297    ActionDispatchNotification {
2298        action_id: TypeId,
2299    },
2300    WindowShouldCloseSubscription {
2301        window_id: usize,
2302        callback: WindowShouldCloseSubscriptionCallback,
2303    },
2304    ActiveLabeledTasksChanged,
2305    ActiveLabeledTasksObservation {
2306        subscription_id: usize,
2307        callback: ActiveLabeledTasksCallback,
2308    },
2309}
2310
2311impl Debug for Effect {
2312    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2313        match self {
2314            Effect::Subscription {
2315                entity_id,
2316                subscription_id,
2317                ..
2318            } => f
2319                .debug_struct("Effect::Subscribe")
2320                .field("entity_id", entity_id)
2321                .field("subscription_id", subscription_id)
2322                .finish(),
2323            Effect::Event { entity_id, .. } => f
2324                .debug_struct("Effect::Event")
2325                .field("entity_id", entity_id)
2326                .finish(),
2327            Effect::GlobalSubscription {
2328                type_id,
2329                subscription_id,
2330                ..
2331            } => f
2332                .debug_struct("Effect::Subscribe")
2333                .field("type_id", type_id)
2334                .field("subscription_id", subscription_id)
2335                .finish(),
2336            Effect::GlobalEvent { payload, .. } => f
2337                .debug_struct("Effect::GlobalEvent")
2338                .field("type_id", &(&*payload).type_id())
2339                .finish(),
2340            Effect::Observation {
2341                entity_id,
2342                subscription_id,
2343                ..
2344            } => f
2345                .debug_struct("Effect::Observation")
2346                .field("entity_id", entity_id)
2347                .field("subscription_id", subscription_id)
2348                .finish(),
2349            Effect::ModelNotification { model_id } => f
2350                .debug_struct("Effect::ModelNotification")
2351                .field("model_id", model_id)
2352                .finish(),
2353            Effect::ViewNotification { window_id, view_id } => f
2354                .debug_struct("Effect::ViewNotification")
2355                .field("window_id", window_id)
2356                .field("view_id", view_id)
2357                .finish(),
2358            Effect::GlobalNotification { type_id } => f
2359                .debug_struct("Effect::GlobalNotification")
2360                .field("type_id", type_id)
2361                .finish(),
2362            Effect::Deferred { .. } => f.debug_struct("Effect::Deferred").finish(),
2363            Effect::ModelRelease { model_id, .. } => f
2364                .debug_struct("Effect::ModelRelease")
2365                .field("model_id", model_id)
2366                .finish(),
2367            Effect::ViewRelease { view_id, .. } => f
2368                .debug_struct("Effect::ViewRelease")
2369                .field("view_id", view_id)
2370                .finish(),
2371            Effect::Focus(focus) => f.debug_tuple("Effect::Focus").field(focus).finish(),
2372            Effect::FocusObservation {
2373                view_id,
2374                subscription_id,
2375                ..
2376            } => f
2377                .debug_struct("Effect::FocusObservation")
2378                .field("view_id", view_id)
2379                .field("subscription_id", subscription_id)
2380                .finish(),
2381            Effect::ActionDispatchNotification { action_id, .. } => f
2382                .debug_struct("Effect::ActionDispatchNotification")
2383                .field("action_id", action_id)
2384                .finish(),
2385            Effect::ResizeWindow { window_id } => f
2386                .debug_struct("Effect::RefreshWindow")
2387                .field("window_id", window_id)
2388                .finish(),
2389            Effect::MoveWindow { window_id } => f
2390                .debug_struct("Effect::MoveWindow")
2391                .field("window_id", window_id)
2392                .finish(),
2393            Effect::WindowActivationObservation {
2394                window_id,
2395                subscription_id,
2396                ..
2397            } => f
2398                .debug_struct("Effect::WindowActivationObservation")
2399                .field("window_id", window_id)
2400                .field("subscription_id", subscription_id)
2401                .finish(),
2402            Effect::ActivateWindow {
2403                window_id,
2404                is_active,
2405            } => f
2406                .debug_struct("Effect::ActivateWindow")
2407                .field("window_id", window_id)
2408                .field("is_active", is_active)
2409                .finish(),
2410            Effect::FullscreenWindow {
2411                window_id,
2412                is_fullscreen,
2413            } => f
2414                .debug_struct("Effect::FullscreenWindow")
2415                .field("window_id", window_id)
2416                .field("is_fullscreen", is_fullscreen)
2417                .finish(),
2418            Effect::WindowFullscreenObservation {
2419                window_id,
2420                subscription_id,
2421                callback: _,
2422            } => f
2423                .debug_struct("Effect::WindowFullscreenObservation")
2424                .field("window_id", window_id)
2425                .field("subscription_id", subscription_id)
2426                .finish(),
2427
2428            Effect::WindowBoundsObservation {
2429                window_id,
2430                subscription_id,
2431                callback: _,
2432            } => f
2433                .debug_struct("Effect::WindowBoundsObservation")
2434                .field("window_id", window_id)
2435                .field("subscription_id", subscription_id)
2436                .finish(),
2437            Effect::RefreshWindows => f.debug_struct("Effect::FullViewRefresh").finish(),
2438            Effect::WindowShouldCloseSubscription { window_id, .. } => f
2439                .debug_struct("Effect::WindowShouldCloseSubscription")
2440                .field("window_id", window_id)
2441                .finish(),
2442            Effect::Keystroke {
2443                window_id,
2444                keystroke,
2445                handled_by,
2446                result,
2447            } => f
2448                .debug_struct("Effect::Keystroke")
2449                .field("window_id", window_id)
2450                .field("keystroke", keystroke)
2451                .field(
2452                    "keystroke",
2453                    &handled_by.as_ref().map(|handled_by| handled_by.name()),
2454                )
2455                .field("result", result)
2456                .finish(),
2457            Effect::ActiveLabeledTasksChanged => {
2458                f.debug_struct("Effect::ActiveLabeledTasksChanged").finish()
2459            }
2460            Effect::ActiveLabeledTasksObservation {
2461                subscription_id,
2462                callback: _,
2463            } => f
2464                .debug_struct("Effect::ActiveLabeledTasksObservation")
2465                .field("subscription_id", subscription_id)
2466                .finish(),
2467        }
2468    }
2469}
2470
2471pub trait AnyModel {
2472    fn as_any(&self) -> &dyn Any;
2473    fn as_any_mut(&mut self) -> &mut dyn Any;
2474    fn release(&mut self, cx: &mut AppContext);
2475    fn app_will_quit(
2476        &mut self,
2477        cx: &mut AppContext,
2478    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2479}
2480
2481impl<T> AnyModel for T
2482where
2483    T: Entity,
2484{
2485    fn as_any(&self) -> &dyn Any {
2486        self
2487    }
2488
2489    fn as_any_mut(&mut self) -> &mut dyn Any {
2490        self
2491    }
2492
2493    fn release(&mut self, cx: &mut AppContext) {
2494        self.release(cx);
2495    }
2496
2497    fn app_will_quit(
2498        &mut self,
2499        cx: &mut AppContext,
2500    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2501        self.app_will_quit(cx)
2502    }
2503}
2504
2505pub trait AnyView {
2506    fn as_any(&self) -> &dyn Any;
2507    fn as_any_mut(&mut self) -> &mut dyn Any;
2508    fn release(&mut self, cx: &mut AppContext);
2509    fn app_will_quit(
2510        &mut self,
2511        cx: &mut AppContext,
2512    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2513    fn ui_name(&self) -> &'static str;
2514    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement>;
2515    fn focus_in<'a, 'b>(&mut self, focused_id: usize, cx: &mut WindowContext<'a>, view_id: usize);
2516    fn focus_out(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize);
2517    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2518    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2519    fn modifiers_changed(
2520        &mut self,
2521        event: &ModifiersChangedEvent,
2522        cx: &mut WindowContext,
2523        view_id: usize,
2524    ) -> bool;
2525    fn update_keymap_context(&self, keymap: &mut KeymapContext, cx: &AppContext);
2526    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value;
2527
2528    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String>;
2529    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2530    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2531    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize);
2532    fn replace_text_in_range(
2533        &mut self,
2534        range: Option<Range<usize>>,
2535        text: &str,
2536        cx: &mut WindowContext,
2537        view_id: usize,
2538    );
2539    fn replace_and_mark_text_in_range(
2540        &mut self,
2541        range: Option<Range<usize>>,
2542        new_text: &str,
2543        new_selected_range: Option<Range<usize>>,
2544        cx: &mut WindowContext,
2545        view_id: usize,
2546    );
2547    fn any_handle(&self, window_id: usize, view_id: usize, cx: &AppContext) -> AnyViewHandle {
2548        AnyViewHandle::new(
2549            window_id,
2550            view_id,
2551            self.as_any().type_id(),
2552            cx.ref_counts.clone(),
2553        )
2554    }
2555}
2556
2557impl<V> AnyView for V
2558where
2559    V: View,
2560{
2561    fn as_any(&self) -> &dyn Any {
2562        self
2563    }
2564
2565    fn as_any_mut(&mut self) -> &mut dyn Any {
2566        self
2567    }
2568
2569    fn release(&mut self, cx: &mut AppContext) {
2570        self.release(cx);
2571    }
2572
2573    fn app_will_quit(
2574        &mut self,
2575        cx: &mut AppContext,
2576    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2577        self.app_will_quit(cx)
2578    }
2579
2580    fn ui_name(&self) -> &'static str {
2581        V::ui_name()
2582    }
2583
2584    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement> {
2585        let mut view_context = ViewContext::mutable(cx, view_id);
2586        let element = V::render(self, &mut view_context);
2587        let view = WeakViewHandle::new(cx.window_id, view_id);
2588        Box::new(RootElement::new(element, view))
2589    }
2590
2591    fn focus_in(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize) {
2592        let mut cx = ViewContext::mutable(cx, view_id);
2593        let focused_view_handle: AnyViewHandle = if view_id == focused_id {
2594            cx.handle().into_any()
2595        } else {
2596            let focused_type = cx
2597                .views_metadata
2598                .get(&(cx.window_id, focused_id))
2599                .unwrap()
2600                .type_id;
2601            AnyViewHandle::new(
2602                cx.window_id,
2603                focused_id,
2604                focused_type,
2605                cx.ref_counts.clone(),
2606            )
2607        };
2608        View::focus_in(self, focused_view_handle, &mut cx);
2609    }
2610
2611    fn focus_out(&mut self, blurred_id: usize, cx: &mut WindowContext, view_id: usize) {
2612        let mut cx = ViewContext::mutable(cx, view_id);
2613        let blurred_view_handle: AnyViewHandle = if view_id == blurred_id {
2614            cx.handle().into_any()
2615        } else {
2616            let blurred_type = cx
2617                .views_metadata
2618                .get(&(cx.window_id, blurred_id))
2619                .unwrap()
2620                .type_id;
2621            AnyViewHandle::new(
2622                cx.window_id,
2623                blurred_id,
2624                blurred_type,
2625                cx.ref_counts.clone(),
2626            )
2627        };
2628        View::focus_out(self, blurred_view_handle, &mut cx);
2629    }
2630
2631    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2632        let mut cx = ViewContext::mutable(cx, view_id);
2633        View::key_down(self, event, &mut cx)
2634    }
2635
2636    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2637        let mut cx = ViewContext::mutable(cx, view_id);
2638        View::key_up(self, event, &mut cx)
2639    }
2640
2641    fn modifiers_changed(
2642        &mut self,
2643        event: &ModifiersChangedEvent,
2644        cx: &mut WindowContext,
2645        view_id: usize,
2646    ) -> bool {
2647        let mut cx = ViewContext::mutable(cx, view_id);
2648        View::modifiers_changed(self, event, &mut cx)
2649    }
2650
2651    fn update_keymap_context(&self, keymap: &mut KeymapContext, cx: &AppContext) {
2652        View::update_keymap_context(self, keymap, cx)
2653    }
2654
2655    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value {
2656        View::debug_json(self, cx)
2657    }
2658
2659    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String> {
2660        View::text_for_range(self, range, cx)
2661    }
2662
2663    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2664        View::selected_text_range(self, cx)
2665    }
2666
2667    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2668        View::marked_text_range(self, cx)
2669    }
2670
2671    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize) {
2672        let mut cx = ViewContext::mutable(cx, view_id);
2673        View::unmark_text(self, &mut cx)
2674    }
2675
2676    fn replace_text_in_range(
2677        &mut self,
2678        range: Option<Range<usize>>,
2679        text: &str,
2680        cx: &mut WindowContext,
2681        view_id: usize,
2682    ) {
2683        let mut cx = ViewContext::mutable(cx, view_id);
2684        View::replace_text_in_range(self, range, text, &mut cx)
2685    }
2686
2687    fn replace_and_mark_text_in_range(
2688        &mut self,
2689        range: Option<Range<usize>>,
2690        new_text: &str,
2691        new_selected_range: Option<Range<usize>>,
2692        cx: &mut WindowContext,
2693        view_id: usize,
2694    ) {
2695        let mut cx = ViewContext::mutable(cx, view_id);
2696        View::replace_and_mark_text_in_range(self, range, new_text, new_selected_range, &mut cx)
2697    }
2698}
2699
2700pub struct ModelContext<'a, T: ?Sized> {
2701    app: &'a mut AppContext,
2702    model_id: usize,
2703    model_type: PhantomData<T>,
2704    halt_stream: bool,
2705}
2706
2707impl<'a, T: Entity> ModelContext<'a, T> {
2708    fn new(app: &'a mut AppContext, model_id: usize) -> Self {
2709        Self {
2710            app,
2711            model_id,
2712            model_type: PhantomData,
2713            halt_stream: false,
2714        }
2715    }
2716
2717    pub fn background(&self) -> &Arc<executor::Background> {
2718        &self.app.background
2719    }
2720
2721    pub fn halt_stream(&mut self) {
2722        self.halt_stream = true;
2723    }
2724
2725    pub fn model_id(&self) -> usize {
2726        self.model_id
2727    }
2728
2729    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
2730    where
2731        S: Entity,
2732        F: FnOnce(&mut ModelContext<S>) -> S,
2733    {
2734        self.app.add_model(build_model)
2735    }
2736
2737    pub fn emit(&mut self, payload: T::Event) {
2738        self.app.pending_effects.push_back(Effect::Event {
2739            entity_id: self.model_id,
2740            payload: Box::new(payload),
2741        });
2742    }
2743
2744    pub fn notify(&mut self) {
2745        self.app.notify_model(self.model_id);
2746    }
2747
2748    pub fn subscribe<S: Entity, F>(
2749        &mut self,
2750        handle: &ModelHandle<S>,
2751        mut callback: F,
2752    ) -> Subscription
2753    where
2754        S::Event: 'static,
2755        F: 'static + FnMut(&mut T, ModelHandle<S>, &S::Event, &mut ModelContext<T>),
2756    {
2757        let subscriber = self.weak_handle();
2758        self.app
2759            .subscribe_internal(handle, move |emitter, event, cx| {
2760                if let Some(subscriber) = subscriber.upgrade(cx) {
2761                    subscriber.update(cx, |subscriber, cx| {
2762                        callback(subscriber, emitter, event, cx);
2763                    });
2764                    true
2765                } else {
2766                    false
2767                }
2768            })
2769    }
2770
2771    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F) -> Subscription
2772    where
2773        S: Entity,
2774        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
2775    {
2776        let observer = self.weak_handle();
2777        self.app.observe_internal(handle, move |observed, cx| {
2778            if let Some(observer) = observer.upgrade(cx) {
2779                observer.update(cx, |observer, cx| {
2780                    callback(observer, observed, cx);
2781                });
2782                true
2783            } else {
2784                false
2785            }
2786        })
2787    }
2788
2789    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
2790    where
2791        G: Any,
2792        F: 'static + FnMut(&mut T, &mut ModelContext<T>),
2793    {
2794        let observer = self.weak_handle();
2795        self.app.observe_global::<G, _>(move |cx| {
2796            if let Some(observer) = observer.upgrade(cx) {
2797                observer.update(cx, |observer, cx| callback(observer, cx));
2798            }
2799        })
2800    }
2801
2802    pub fn observe_release<S, F>(
2803        &mut self,
2804        handle: &ModelHandle<S>,
2805        mut callback: F,
2806    ) -> Subscription
2807    where
2808        S: Entity,
2809        F: 'static + FnMut(&mut T, &S, &mut ModelContext<T>),
2810    {
2811        let observer = self.weak_handle();
2812        self.app.observe_release(handle, move |released, cx| {
2813            if let Some(observer) = observer.upgrade(cx) {
2814                observer.update(cx, |observer, cx| {
2815                    callback(observer, released, cx);
2816                });
2817            }
2818        })
2819    }
2820
2821    pub fn handle(&self) -> ModelHandle<T> {
2822        ModelHandle::new(self.model_id, &self.app.ref_counts)
2823    }
2824
2825    pub fn weak_handle(&self) -> WeakModelHandle<T> {
2826        WeakModelHandle::new(self.model_id)
2827    }
2828
2829    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
2830    where
2831        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
2832        Fut: 'static + Future<Output = S>,
2833        S: 'static,
2834    {
2835        let handle = self.handle();
2836        self.app.spawn(|cx| f(handle, cx))
2837    }
2838
2839    pub fn spawn_weak<F, Fut, S>(&mut self, f: F) -> Task<S>
2840    where
2841        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
2842        Fut: 'static + Future<Output = S>,
2843        S: 'static,
2844    {
2845        let handle = self.weak_handle();
2846        self.app.spawn(|cx| f(handle, cx))
2847    }
2848}
2849
2850impl<M> AsRef<AppContext> for ModelContext<'_, M> {
2851    fn as_ref(&self) -> &AppContext {
2852        &self.app
2853    }
2854}
2855
2856impl<M> AsMut<AppContext> for ModelContext<'_, M> {
2857    fn as_mut(&mut self) -> &mut AppContext {
2858        self.app
2859    }
2860}
2861
2862impl<M> BorrowAppContext for ModelContext<'_, M> {
2863    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
2864        self.app.read_with(f)
2865    }
2866
2867    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
2868        self.app.update(f)
2869    }
2870}
2871
2872impl<M> Deref for ModelContext<'_, M> {
2873    type Target = AppContext;
2874
2875    fn deref(&self) -> &Self::Target {
2876        self.app
2877    }
2878}
2879
2880impl<M> DerefMut for ModelContext<'_, M> {
2881    fn deref_mut(&mut self) -> &mut Self::Target {
2882        &mut self.app
2883    }
2884}
2885
2886pub struct ViewContext<'a, 'b, T: ?Sized> {
2887    window_context: Reference<'b, WindowContext<'a>>,
2888    view_id: usize,
2889    view_type: PhantomData<T>,
2890}
2891
2892impl<'a, 'b, T: View> Deref for ViewContext<'a, 'b, T> {
2893    type Target = WindowContext<'a>;
2894
2895    fn deref(&self) -> &Self::Target {
2896        &self.window_context
2897    }
2898}
2899
2900impl<T: View> DerefMut for ViewContext<'_, '_, T> {
2901    fn deref_mut(&mut self) -> &mut Self::Target {
2902        &mut self.window_context
2903    }
2904}
2905
2906impl<'a, 'b, V: View> ViewContext<'a, 'b, V> {
2907    pub(crate) fn mutable(window_context: &'b mut WindowContext<'a>, view_id: usize) -> Self {
2908        Self {
2909            window_context: Reference::Mutable(window_context),
2910            view_id,
2911            view_type: PhantomData,
2912        }
2913    }
2914
2915    pub(crate) fn immutable(window_context: &'b WindowContext<'a>, view_id: usize) -> Self {
2916        Self {
2917            window_context: Reference::Immutable(window_context),
2918            view_id,
2919            view_type: PhantomData,
2920        }
2921    }
2922
2923    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2924        &mut self.window_context
2925    }
2926
2927    pub fn handle(&self) -> ViewHandle<V> {
2928        ViewHandle::new(
2929            self.window_id,
2930            self.view_id,
2931            &self.window_context.ref_counts,
2932        )
2933    }
2934
2935    pub fn weak_handle(&self) -> WeakViewHandle<V> {
2936        WeakViewHandle::new(self.window_id, self.view_id)
2937    }
2938
2939    pub fn window_id(&self) -> usize {
2940        self.window_id
2941    }
2942
2943    pub fn view_id(&self) -> usize {
2944        self.view_id
2945    }
2946
2947    pub fn foreground(&self) -> &Rc<executor::Foreground> {
2948        self.window_context.foreground()
2949    }
2950
2951    pub fn background_executor(&self) -> &Arc<executor::Background> {
2952        &self.window_context.background
2953    }
2954
2955    pub fn platform(&self) -> &Arc<dyn Platform> {
2956        self.window_context.platform()
2957    }
2958
2959    pub fn prompt_for_paths(
2960        &self,
2961        options: PathPromptOptions,
2962    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
2963        self.window_context.prompt_for_paths(options)
2964    }
2965
2966    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
2967        self.window_context.prompt_for_new_path(directory)
2968    }
2969
2970    pub fn reveal_path(&self, path: &Path) {
2971        self.window_context.reveal_path(path)
2972    }
2973
2974    pub fn focus(&mut self, handle: &AnyViewHandle) {
2975        self.window_context.focus(Some(handle.view_id));
2976    }
2977
2978    pub fn focus_self(&mut self) {
2979        let view_id = self.view_id;
2980        self.window_context.focus(Some(view_id));
2981    }
2982
2983    pub fn is_self_focused(&self) -> bool {
2984        self.window.focused_view_id == Some(self.view_id)
2985    }
2986
2987    pub fn focus_parent(&mut self) {
2988        let window_id = self.window_id;
2989        let view_id = self.view_id;
2990        self.pending_effects
2991            .push_back(Effect::Focus(FocusEffect::ViewParent {
2992                window_id,
2993                view_id,
2994                is_forced: false,
2995            }));
2996    }
2997
2998    pub fn blur(&mut self) {
2999        self.window_context.focus(None);
3000    }
3001
3002    pub fn on_window_should_close<F>(&mut self, mut callback: F)
3003    where
3004        F: 'static + FnMut(&mut V, &mut ViewContext<V>) -> bool,
3005    {
3006        let window_id = self.window_id;
3007        let view = self.weak_handle();
3008        self.pending_effects
3009            .push_back(Effect::WindowShouldCloseSubscription {
3010                window_id,
3011                callback: Box::new(move |cx| {
3012                    cx.update_window(window_id, |cx| {
3013                        if let Some(view) = view.upgrade(cx) {
3014                            view.update(cx, |view, cx| callback(view, cx))
3015                        } else {
3016                            true
3017                        }
3018                    })
3019                    .unwrap_or(true)
3020                }),
3021            });
3022    }
3023
3024    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
3025    where
3026        E: Entity,
3027        E::Event: 'static,
3028        H: Handle<E>,
3029        F: 'static + FnMut(&mut V, H, &E::Event, &mut ViewContext<V>),
3030    {
3031        let subscriber = self.weak_handle();
3032        self.window_context
3033            .subscribe_internal(handle, move |emitter, event, cx| {
3034                if let Some(subscriber) = subscriber.upgrade(cx) {
3035                    subscriber.update(cx, |subscriber, cx| {
3036                        callback(subscriber, emitter, event, cx);
3037                    });
3038                    true
3039                } else {
3040                    false
3041                }
3042            })
3043    }
3044
3045    pub fn observe<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3046    where
3047        E: Entity,
3048        H: Handle<E>,
3049        F: 'static + FnMut(&mut V, H, &mut ViewContext<V>),
3050    {
3051        let window_id = self.window_id;
3052        let observer = self.weak_handle();
3053        self.window_context
3054            .observe_internal(handle, move |observed, cx| {
3055                cx.update_window(window_id, |cx| {
3056                    if let Some(observer) = observer.upgrade(cx) {
3057                        observer.update(cx, |observer, cx| {
3058                            callback(observer, observed, cx);
3059                        });
3060                        true
3061                    } else {
3062                        false
3063                    }
3064                })
3065                .unwrap_or(false)
3066            })
3067    }
3068
3069    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
3070    where
3071        G: Any,
3072        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
3073    {
3074        let window_id = self.window_id;
3075        let observer = self.weak_handle();
3076        self.window_context.observe_global::<G, _>(move |cx| {
3077            cx.update_window(window_id, |cx| {
3078                if let Some(observer) = observer.upgrade(cx) {
3079                    observer.update(cx, |observer, cx| callback(observer, cx));
3080                }
3081            });
3082        })
3083    }
3084
3085    pub fn observe_focus<F, W>(&mut self, handle: &ViewHandle<W>, mut callback: F) -> Subscription
3086    where
3087        F: 'static + FnMut(&mut V, ViewHandle<W>, bool, &mut ViewContext<V>),
3088        W: View,
3089    {
3090        let observer = self.weak_handle();
3091        self.window_context
3092            .observe_focus(handle, move |observed, focused, cx| {
3093                if let Some(observer) = observer.upgrade(cx) {
3094                    observer.update(cx, |observer, cx| {
3095                        callback(observer, observed, focused, cx);
3096                    });
3097                    true
3098                } else {
3099                    false
3100                }
3101            })
3102    }
3103
3104    pub fn observe_release<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3105    where
3106        E: Entity,
3107        H: Handle<E>,
3108        F: 'static + FnMut(&mut V, &E, &mut ViewContext<V>),
3109    {
3110        let window_id = self.window_id;
3111        let observer = self.weak_handle();
3112        self.window_context
3113            .observe_release(handle, move |released, cx| {
3114                cx.update_window(window_id, |cx| {
3115                    if let Some(observer) = observer.upgrade(cx) {
3116                        observer.update(cx, |observer, cx| {
3117                            callback(observer, released, cx);
3118                        });
3119                    }
3120                });
3121            })
3122    }
3123
3124    pub fn observe_actions<F>(&mut self, mut callback: F) -> Subscription
3125    where
3126        F: 'static + FnMut(&mut V, TypeId, &mut ViewContext<V>),
3127    {
3128        let window_id = self.window_id;
3129        let observer = self.weak_handle();
3130        self.window_context.observe_actions(move |action_id, cx| {
3131            cx.update_window(window_id, |cx| {
3132                if let Some(observer) = observer.upgrade(cx) {
3133                    observer.update(cx, |observer, cx| {
3134                        callback(observer, action_id, cx);
3135                    });
3136                }
3137            });
3138        })
3139    }
3140
3141    pub fn observe_window_activation<F>(&mut self, mut callback: F) -> Subscription
3142    where
3143        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3144    {
3145        let observer = self.weak_handle();
3146        self.window_context
3147            .observe_window_activation(move |active, cx| {
3148                if let Some(observer) = observer.upgrade(cx) {
3149                    observer.update(cx, |observer, cx| {
3150                        callback(observer, active, cx);
3151                    });
3152                    true
3153                } else {
3154                    false
3155                }
3156            })
3157    }
3158
3159    pub fn observe_fullscreen<F>(&mut self, mut callback: F) -> Subscription
3160    where
3161        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3162    {
3163        let observer = self.weak_handle();
3164        self.window_context.observe_fullscreen(move |active, cx| {
3165            if let Some(observer) = observer.upgrade(cx) {
3166                observer.update(cx, |observer, cx| {
3167                    callback(observer, active, cx);
3168                });
3169                true
3170            } else {
3171                false
3172            }
3173        })
3174    }
3175
3176    pub fn observe_keystrokes<F>(&mut self, mut callback: F) -> Subscription
3177    where
3178        F: 'static
3179            + FnMut(
3180                &mut V,
3181                &Keystroke,
3182                Option<&Box<dyn Action>>,
3183                &MatchResult,
3184                &mut ViewContext<V>,
3185            ) -> bool,
3186    {
3187        let observer = self.weak_handle();
3188        self.window_context
3189            .observe_keystrokes(move |keystroke, result, handled_by, cx| {
3190                if let Some(observer) = observer.upgrade(cx) {
3191                    observer.update(cx, |observer, cx| {
3192                        callback(observer, keystroke, handled_by, result, cx);
3193                    });
3194                    true
3195                } else {
3196                    false
3197                }
3198            })
3199    }
3200
3201    pub fn observe_window_bounds<F>(&mut self, mut callback: F) -> Subscription
3202    where
3203        F: 'static + FnMut(&mut V, WindowBounds, Uuid, &mut ViewContext<V>),
3204    {
3205        let observer = self.weak_handle();
3206        self.window_context
3207            .observe_window_bounds(move |bounds, display, cx| {
3208                if let Some(observer) = observer.upgrade(cx) {
3209                    observer.update(cx, |observer, cx| {
3210                        callback(observer, bounds, display, cx);
3211                    });
3212                    true
3213                } else {
3214                    false
3215                }
3216            })
3217    }
3218
3219    pub fn observe_active_labeled_tasks<F>(&mut self, mut callback: F) -> Subscription
3220    where
3221        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
3222    {
3223        let window_id = self.window_id;
3224        let observer = self.weak_handle();
3225        self.window_context.observe_active_labeled_tasks(move |cx| {
3226            cx.update_window(window_id, |cx| {
3227                if let Some(observer) = observer.upgrade(cx) {
3228                    observer.update(cx, |observer, cx| {
3229                        callback(observer, cx);
3230                    });
3231                    true
3232                } else {
3233                    false
3234                }
3235            })
3236            .unwrap_or(false)
3237        })
3238    }
3239
3240    pub fn emit(&mut self, payload: V::Event) {
3241        self.window_context
3242            .pending_effects
3243            .push_back(Effect::Event {
3244                entity_id: self.view_id,
3245                payload: Box::new(payload),
3246            });
3247    }
3248
3249    pub fn notify(&mut self) {
3250        let window_id = self.window_id;
3251        let view_id = self.view_id;
3252        self.window_context.notify_view(window_id, view_id);
3253    }
3254
3255    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>)) {
3256        let handle = self.handle();
3257        self.window_context
3258            .defer(move |cx| handle.update(cx, |view, cx| callback(view, cx)))
3259    }
3260
3261    pub fn after_window_update(
3262        &mut self,
3263        callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>),
3264    ) {
3265        let window_id = self.window_id;
3266        let handle = self.handle();
3267        self.window_context.after_window_update(move |cx| {
3268            cx.update_window(window_id, |cx| {
3269                handle.update(cx, |view, cx| {
3270                    callback(view, cx);
3271                })
3272            });
3273        })
3274    }
3275
3276    pub fn propagate_action(&mut self) {
3277        self.window_context.halt_action_dispatch = false;
3278    }
3279
3280    pub fn spawn_labeled<F, Fut, S>(&mut self, task_label: &'static str, f: F) -> Task<S>
3281    where
3282        F: FnOnce(WeakViewHandle<V>, AsyncAppContext) -> Fut,
3283        Fut: 'static + Future<Output = S>,
3284        S: 'static,
3285    {
3286        let handle = self.weak_handle();
3287        self.window_context
3288            .spawn_labeled(task_label, |cx| f(handle, cx))
3289    }
3290
3291    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
3292    where
3293        F: FnOnce(WeakViewHandle<V>, AsyncAppContext) -> Fut,
3294        Fut: 'static + Future<Output = S>,
3295        S: 'static,
3296    {
3297        let handle = self.weak_handle();
3298        self.window_context.spawn(|cx| f(handle, cx))
3299    }
3300
3301    pub fn mouse_state<Tag: 'static>(&self, region_id: usize) -> MouseState {
3302        let region_id = MouseRegionId::new::<Tag>(self.view_id, region_id);
3303        MouseState {
3304            hovered: self.window.hovered_region_ids.contains(&region_id),
3305            clicked: if let Some((clicked_region_id, button)) = self.window.clicked_region {
3306                if region_id == clicked_region_id {
3307                    Some(button)
3308                } else {
3309                    None
3310                }
3311            } else {
3312                None
3313            },
3314            accessed_hovered: false,
3315            accessed_clicked: false,
3316        }
3317    }
3318
3319    pub fn element_state<Tag: 'static, T: 'static>(
3320        &mut self,
3321        element_id: usize,
3322        initial: T,
3323    ) -> ElementStateHandle<T> {
3324        let id = ElementStateId {
3325            view_id: self.view_id(),
3326            element_id,
3327            tag: TypeId::of::<Tag>(),
3328        };
3329        self.element_states
3330            .entry(id)
3331            .or_insert_with(|| Box::new(initial));
3332        ElementStateHandle::new(id, self.frame_count, &self.ref_counts)
3333    }
3334
3335    pub fn default_element_state<Tag: 'static, T: 'static + Default>(
3336        &mut self,
3337        element_id: usize,
3338    ) -> ElementStateHandle<T> {
3339        self.element_state::<Tag, T>(element_id, T::default())
3340    }
3341
3342    pub fn rem_pixels(&self) -> f32 {
3343        16.
3344    }
3345}
3346
3347impl<V> BorrowAppContext for ViewContext<'_, '_, V> {
3348    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3349        BorrowAppContext::read_with(&*self.window_context, f)
3350    }
3351
3352    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3353        BorrowAppContext::update(&mut *self.window_context, f)
3354    }
3355}
3356
3357impl<V> BorrowWindowContext for ViewContext<'_, '_, V> {
3358    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3359        BorrowWindowContext::read_with(&*self.window_context, window_id, f)
3360    }
3361
3362    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3363        BorrowWindowContext::update(&mut *self.window_context, window_id, f)
3364    }
3365}
3366
3367pub struct LayoutContext<'a, 'b, 'c, V: View> {
3368    view_context: &'c mut ViewContext<'a, 'b, V>,
3369    new_parents: &'c mut HashMap<usize, usize>,
3370    views_to_notify_if_ancestors_change: &'c mut HashMap<usize, SmallVec<[usize; 2]>>,
3371    text_style_stack: Vec<Arc<TextStyle>>,
3372    pub refreshing: bool,
3373}
3374
3375impl<'a, 'b, 'c, V: View> LayoutContext<'a, 'b, 'c, V> {
3376    pub fn new(
3377        view_context: &'c mut ViewContext<'a, 'b, V>,
3378        new_parents: &'c mut HashMap<usize, usize>,
3379        views_to_notify_if_ancestors_change: &'c mut HashMap<usize, SmallVec<[usize; 2]>>,
3380        refreshing: bool,
3381    ) -> Self {
3382        Self {
3383            view_context,
3384            new_parents,
3385            views_to_notify_if_ancestors_change,
3386            text_style_stack: Vec::new(),
3387            refreshing,
3388        }
3389    }
3390
3391    pub fn view_context(&mut self) -> &mut ViewContext<'a, 'b, V> {
3392        self.view_context
3393    }
3394
3395    /// Return keystrokes that would dispatch the given action on the given view.
3396    pub(crate) fn keystrokes_for_action(
3397        &mut self,
3398        view_id: usize,
3399        action: &dyn Action,
3400    ) -> Option<SmallVec<[Keystroke; 2]>> {
3401        self.notify_if_view_ancestors_change(view_id);
3402
3403        let window_id = self.window_id;
3404        let mut contexts = Vec::new();
3405        let mut handler_depth = None;
3406        for (i, view_id) in self.ancestors(view_id).enumerate() {
3407            if let Some(view_metadata) = self.views_metadata.get(&(window_id, view_id)) {
3408                if let Some(actions) = self.actions.get(&view_metadata.type_id) {
3409                    if actions.contains_key(&action.id()) {
3410                        handler_depth = Some(i);
3411                    }
3412                }
3413                contexts.push(view_metadata.keymap_context.clone());
3414            }
3415        }
3416
3417        if self.global_actions.contains_key(&action.id()) {
3418            handler_depth = Some(contexts.len())
3419        }
3420
3421        let action_contexts = if let Some(depth) = handler_depth {
3422            &contexts[depth..]
3423        } else {
3424            &contexts
3425        };
3426
3427        self.keystroke_matcher
3428            .keystrokes_for_action(action, action_contexts)
3429    }
3430
3431    fn notify_if_view_ancestors_change(&mut self, view_id: usize) {
3432        let self_view_id = self.view_id;
3433        self.views_to_notify_if_ancestors_change
3434            .entry(view_id)
3435            .or_default()
3436            .push(self_view_id);
3437    }
3438
3439    pub fn text_style(&self) -> Arc<TextStyle> {
3440        self.text_style_stack
3441            .last()
3442            .cloned()
3443            .unwrap_or(Default::default())
3444    }
3445
3446    pub fn with_text_style<S, F, T>(&mut self, style: S, f: F) -> T
3447    where
3448        S: Into<Arc<TextStyle>>,
3449        F: FnOnce(&mut Self) -> T,
3450    {
3451        self.text_style_stack.push(style.into());
3452        let result = f(self);
3453        self.text_style_stack.pop();
3454        result
3455    }
3456}
3457
3458impl<'a, 'b, 'c, V: View> Deref for LayoutContext<'a, 'b, 'c, V> {
3459    type Target = ViewContext<'a, 'b, V>;
3460
3461    fn deref(&self) -> &Self::Target {
3462        &self.view_context
3463    }
3464}
3465
3466impl<V: View> DerefMut for LayoutContext<'_, '_, '_, V> {
3467    fn deref_mut(&mut self) -> &mut Self::Target {
3468        &mut self.view_context
3469    }
3470}
3471
3472impl<V: View> BorrowAppContext for LayoutContext<'_, '_, '_, V> {
3473    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3474        BorrowAppContext::read_with(&*self.view_context, f)
3475    }
3476
3477    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3478        BorrowAppContext::update(&mut *self.view_context, f)
3479    }
3480}
3481
3482impl<V: View> BorrowWindowContext for LayoutContext<'_, '_, '_, V> {
3483    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3484        BorrowWindowContext::read_with(&*self.view_context, window_id, f)
3485    }
3486
3487    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3488        BorrowWindowContext::update(&mut *self.view_context, window_id, f)
3489    }
3490}
3491
3492pub struct PaintContext<'a, 'b, 'c, V: View> {
3493    view_context: &'c mut ViewContext<'a, 'b, V>,
3494    text_style_stack: Vec<Arc<TextStyle>>,
3495}
3496
3497impl<'a, 'b, 'c, V: View> PaintContext<'a, 'b, 'c, V> {
3498    pub fn new(view_context: &'c mut ViewContext<'a, 'b, V>) -> Self {
3499        Self {
3500            view_context,
3501            text_style_stack: Vec::new(),
3502        }
3503    }
3504
3505    pub fn text_style(&self) -> Arc<TextStyle> {
3506        self.text_style_stack
3507            .last()
3508            .cloned()
3509            .unwrap_or(Default::default())
3510    }
3511
3512    pub fn with_text_style<S, F, T>(&mut self, style: S, f: F) -> T
3513    where
3514        S: Into<Arc<TextStyle>>,
3515        F: FnOnce(&mut Self) -> T,
3516    {
3517        self.text_style_stack.push(style.into());
3518        let result = f(self);
3519        self.text_style_stack.pop();
3520        result
3521    }
3522}
3523
3524impl<'a, 'b, 'c, V: View> Deref for PaintContext<'a, 'b, 'c, V> {
3525    type Target = ViewContext<'a, 'b, V>;
3526
3527    fn deref(&self) -> &Self::Target {
3528        &self.view_context
3529    }
3530}
3531
3532impl<V: View> DerefMut for PaintContext<'_, '_, '_, V> {
3533    fn deref_mut(&mut self) -> &mut Self::Target {
3534        &mut self.view_context
3535    }
3536}
3537
3538impl<V: View> BorrowAppContext for PaintContext<'_, '_, '_, V> {
3539    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3540        BorrowAppContext::read_with(&*self.view_context, f)
3541    }
3542
3543    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3544        BorrowAppContext::update(&mut *self.view_context, f)
3545    }
3546}
3547
3548impl<V: View> BorrowWindowContext for PaintContext<'_, '_, '_, V> {
3549    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3550        BorrowWindowContext::read_with(&*self.view_context, window_id, f)
3551    }
3552
3553    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3554        BorrowWindowContext::update(&mut *self.view_context, window_id, f)
3555    }
3556}
3557
3558pub struct EventContext<'a, 'b, 'c, V: View> {
3559    view_context: &'c mut ViewContext<'a, 'b, V>,
3560    pub(crate) handled: bool,
3561}
3562
3563impl<'a, 'b, 'c, V: View> EventContext<'a, 'b, 'c, V> {
3564    pub(crate) fn new(view_context: &'c mut ViewContext<'a, 'b, V>) -> Self {
3565        EventContext {
3566            view_context,
3567            handled: true,
3568        }
3569    }
3570
3571    pub fn propagate_event(&mut self) {
3572        self.handled = false;
3573    }
3574}
3575
3576impl<'a, 'b, 'c, V: View> Deref for EventContext<'a, 'b, 'c, V> {
3577    type Target = ViewContext<'a, 'b, V>;
3578
3579    fn deref(&self) -> &Self::Target {
3580        &self.view_context
3581    }
3582}
3583
3584impl<V: View> DerefMut for EventContext<'_, '_, '_, V> {
3585    fn deref_mut(&mut self) -> &mut Self::Target {
3586        &mut self.view_context
3587    }
3588}
3589
3590impl<V: View> BorrowAppContext for EventContext<'_, '_, '_, V> {
3591    fn read_with<T, F: FnOnce(&AppContext) -> T>(&self, f: F) -> T {
3592        BorrowAppContext::read_with(&*self.view_context, f)
3593    }
3594
3595    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, f: F) -> T {
3596        BorrowAppContext::update(&mut *self.view_context, f)
3597    }
3598}
3599
3600impl<V: View> BorrowWindowContext for EventContext<'_, '_, '_, V> {
3601    fn read_with<T, F: FnOnce(&WindowContext) -> T>(&self, window_id: usize, f: F) -> T {
3602        BorrowWindowContext::read_with(&*self.view_context, window_id, f)
3603    }
3604
3605    fn update<T, F: FnOnce(&mut WindowContext) -> T>(&mut self, window_id: usize, f: F) -> T {
3606        BorrowWindowContext::update(&mut *self.view_context, window_id, f)
3607    }
3608}
3609
3610pub(crate) enum Reference<'a, T> {
3611    Immutable(&'a T),
3612    Mutable(&'a mut T),
3613}
3614
3615impl<'a, T> Deref for Reference<'a, T> {
3616    type Target = T;
3617
3618    fn deref(&self) -> &Self::Target {
3619        match self {
3620            Reference::Immutable(target) => target,
3621            Reference::Mutable(target) => target,
3622        }
3623    }
3624}
3625
3626impl<'a, T> DerefMut for Reference<'a, T> {
3627    fn deref_mut(&mut self) -> &mut Self::Target {
3628        match self {
3629            Reference::Immutable(_) => {
3630                panic!("cannot mutably deref an immutable reference. this is a bug in GPUI.");
3631            }
3632            Reference::Mutable(target) => target,
3633        }
3634    }
3635}
3636
3637#[derive(Debug, Clone, Default)]
3638pub struct MouseState {
3639    pub(crate) hovered: bool,
3640    pub(crate) clicked: Option<MouseButton>,
3641    pub(crate) accessed_hovered: bool,
3642    pub(crate) accessed_clicked: bool,
3643}
3644
3645impl MouseState {
3646    pub fn hovered(&mut self) -> bool {
3647        self.accessed_hovered = true;
3648        self.hovered
3649    }
3650
3651    pub fn clicked(&mut self) -> Option<MouseButton> {
3652        self.accessed_clicked = true;
3653        self.clicked
3654    }
3655
3656    pub fn accessed_hovered(&self) -> bool {
3657        self.accessed_hovered
3658    }
3659
3660    pub fn accessed_clicked(&self) -> bool {
3661        self.accessed_clicked
3662    }
3663}
3664
3665pub trait Handle<T> {
3666    type Weak: 'static;
3667    fn id(&self) -> usize;
3668    fn location(&self) -> EntityLocation;
3669    fn downgrade(&self) -> Self::Weak;
3670    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3671    where
3672        Self: Sized;
3673}
3674
3675pub trait WeakHandle {
3676    fn id(&self) -> usize;
3677}
3678
3679#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
3680pub enum EntityLocation {
3681    Model(usize),
3682    View(usize, usize),
3683}
3684
3685pub struct ModelHandle<T: Entity> {
3686    any_handle: AnyModelHandle,
3687    model_type: PhantomData<T>,
3688}
3689
3690impl<T: Entity> Deref for ModelHandle<T> {
3691    type Target = AnyModelHandle;
3692
3693    fn deref(&self) -> &Self::Target {
3694        &self.any_handle
3695    }
3696}
3697
3698impl<T: Entity> ModelHandle<T> {
3699    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3700        Self {
3701            any_handle: AnyModelHandle::new(model_id, TypeId::of::<T>(), ref_counts.clone()),
3702            model_type: PhantomData,
3703        }
3704    }
3705
3706    pub fn downgrade(&self) -> WeakModelHandle<T> {
3707        WeakModelHandle::new(self.model_id)
3708    }
3709
3710    pub fn id(&self) -> usize {
3711        self.model_id
3712    }
3713
3714    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
3715        cx.read_model(self)
3716    }
3717
3718    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
3719    where
3720        C: BorrowAppContext,
3721        F: FnOnce(&T, &AppContext) -> S,
3722    {
3723        cx.read_with(|cx| read(self.read(cx), cx))
3724    }
3725
3726    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
3727    where
3728        C: BorrowAppContext,
3729        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
3730    {
3731        let mut update = Some(update);
3732        cx.update(|cx| {
3733            cx.update_model(self, &mut |model, cx| {
3734                let update = update.take().unwrap();
3735                update(model, cx)
3736            })
3737        })
3738    }
3739}
3740
3741impl<T: Entity> Clone for ModelHandle<T> {
3742    fn clone(&self) -> Self {
3743        Self::new(self.model_id, &self.ref_counts)
3744    }
3745}
3746
3747impl<T: Entity> PartialEq for ModelHandle<T> {
3748    fn eq(&self, other: &Self) -> bool {
3749        self.model_id == other.model_id
3750    }
3751}
3752
3753impl<T: Entity> Eq for ModelHandle<T> {}
3754
3755impl<T: Entity> PartialEq<WeakModelHandle<T>> for ModelHandle<T> {
3756    fn eq(&self, other: &WeakModelHandle<T>) -> bool {
3757        self.model_id == other.model_id
3758    }
3759}
3760
3761impl<T: Entity> Hash for ModelHandle<T> {
3762    fn hash<H: Hasher>(&self, state: &mut H) {
3763        self.model_id.hash(state);
3764    }
3765}
3766
3767impl<T: Entity> std::borrow::Borrow<usize> for ModelHandle<T> {
3768    fn borrow(&self) -> &usize {
3769        &self.model_id
3770    }
3771}
3772
3773impl<T: Entity> Debug for ModelHandle<T> {
3774    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
3775        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
3776            .field(&self.model_id)
3777            .finish()
3778    }
3779}
3780
3781unsafe impl<T: Entity> Send for ModelHandle<T> {}
3782unsafe impl<T: Entity> Sync for ModelHandle<T> {}
3783
3784impl<T: Entity> Handle<T> for ModelHandle<T> {
3785    type Weak = WeakModelHandle<T>;
3786
3787    fn id(&self) -> usize {
3788        self.model_id
3789    }
3790
3791    fn location(&self) -> EntityLocation {
3792        EntityLocation::Model(self.model_id)
3793    }
3794
3795    fn downgrade(&self) -> Self::Weak {
3796        self.downgrade()
3797    }
3798
3799    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3800    where
3801        Self: Sized,
3802    {
3803        weak.upgrade(cx)
3804    }
3805}
3806
3807pub struct WeakModelHandle<T> {
3808    any_handle: AnyWeakModelHandle,
3809    model_type: PhantomData<T>,
3810}
3811
3812impl<T> WeakModelHandle<T> {
3813    pub fn into_any(self) -> AnyWeakModelHandle {
3814        self.any_handle
3815    }
3816}
3817
3818impl<T> Deref for WeakModelHandle<T> {
3819    type Target = AnyWeakModelHandle;
3820
3821    fn deref(&self) -> &Self::Target {
3822        &self.any_handle
3823    }
3824}
3825
3826impl<T> WeakHandle for WeakModelHandle<T> {
3827    fn id(&self) -> usize {
3828        self.model_id
3829    }
3830}
3831
3832unsafe impl<T> Send for WeakModelHandle<T> {}
3833unsafe impl<T> Sync for WeakModelHandle<T> {}
3834
3835impl<T: Entity> WeakModelHandle<T> {
3836    fn new(model_id: usize) -> Self {
3837        Self {
3838            any_handle: AnyWeakModelHandle {
3839                model_id,
3840                model_type: TypeId::of::<T>(),
3841            },
3842            model_type: PhantomData,
3843        }
3844    }
3845
3846    pub fn id(&self) -> usize {
3847        self.model_id
3848    }
3849
3850    pub fn is_upgradable(&self, cx: &impl BorrowAppContext) -> bool {
3851        cx.read_with(|cx| cx.model_handle_is_upgradable(self))
3852    }
3853
3854    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<ModelHandle<T>> {
3855        cx.read_with(|cx| cx.upgrade_model_handle(self))
3856    }
3857}
3858
3859impl<T> Hash for WeakModelHandle<T> {
3860    fn hash<H: Hasher>(&self, state: &mut H) {
3861        self.model_id.hash(state)
3862    }
3863}
3864
3865impl<T> PartialEq for WeakModelHandle<T> {
3866    fn eq(&self, other: &Self) -> bool {
3867        self.model_id == other.model_id
3868    }
3869}
3870
3871impl<T> Eq for WeakModelHandle<T> {}
3872
3873impl<T: Entity> PartialEq<ModelHandle<T>> for WeakModelHandle<T> {
3874    fn eq(&self, other: &ModelHandle<T>) -> bool {
3875        self.model_id == other.model_id
3876    }
3877}
3878
3879impl<T> Clone for WeakModelHandle<T> {
3880    fn clone(&self) -> Self {
3881        Self {
3882            any_handle: self.any_handle.clone(),
3883            model_type: PhantomData,
3884        }
3885    }
3886}
3887
3888impl<T> Copy for WeakModelHandle<T> {}
3889
3890#[repr(transparent)]
3891pub struct ViewHandle<T> {
3892    any_handle: AnyViewHandle,
3893    view_type: PhantomData<T>,
3894}
3895
3896impl<T> Deref for ViewHandle<T> {
3897    type Target = AnyViewHandle;
3898
3899    fn deref(&self) -> &Self::Target {
3900        &self.any_handle
3901    }
3902}
3903
3904impl<T: View> ViewHandle<T> {
3905    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3906        Self {
3907            any_handle: AnyViewHandle::new(
3908                window_id,
3909                view_id,
3910                TypeId::of::<T>(),
3911                ref_counts.clone(),
3912            ),
3913            view_type: PhantomData,
3914        }
3915    }
3916
3917    pub fn downgrade(&self) -> WeakViewHandle<T> {
3918        WeakViewHandle::new(self.window_id, self.view_id)
3919    }
3920
3921    pub fn into_any(self) -> AnyViewHandle {
3922        self.any_handle
3923    }
3924
3925    pub fn window_id(&self) -> usize {
3926        self.window_id
3927    }
3928
3929    pub fn id(&self) -> usize {
3930        self.view_id
3931    }
3932
3933    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
3934        cx.read_view(self)
3935    }
3936
3937    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
3938    where
3939        C: BorrowWindowContext,
3940        F: FnOnce(&T, &ViewContext<T>) -> S,
3941    {
3942        cx.read_with(self.window_id, |cx| {
3943            let cx = ViewContext::immutable(cx, self.view_id);
3944            read(cx.read_view(self), &cx)
3945        })
3946    }
3947
3948    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
3949    where
3950        C: BorrowWindowContext,
3951        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
3952    {
3953        let mut update = Some(update);
3954
3955        cx.update(self.window_id, |cx| {
3956            cx.update_view(self, &mut |view, cx| {
3957                let update = update.take().unwrap();
3958                update(view, cx)
3959            })
3960        })
3961    }
3962
3963    pub fn is_focused(&self, cx: &WindowContext) -> bool {
3964        cx.focused_view_id() == Some(self.view_id)
3965    }
3966}
3967
3968impl<T: View> Clone for ViewHandle<T> {
3969    fn clone(&self) -> Self {
3970        ViewHandle::new(self.window_id, self.view_id, &self.ref_counts)
3971    }
3972}
3973
3974impl<T> PartialEq for ViewHandle<T> {
3975    fn eq(&self, other: &Self) -> bool {
3976        self.window_id == other.window_id && self.view_id == other.view_id
3977    }
3978}
3979
3980impl<T> PartialEq<AnyViewHandle> for ViewHandle<T> {
3981    fn eq(&self, other: &AnyViewHandle) -> bool {
3982        self.window_id == other.window_id && self.view_id == other.view_id
3983    }
3984}
3985
3986impl<T> PartialEq<WeakViewHandle<T>> for ViewHandle<T> {
3987    fn eq(&self, other: &WeakViewHandle<T>) -> bool {
3988        self.window_id == other.window_id && self.view_id == other.view_id
3989    }
3990}
3991
3992impl<T> PartialEq<ViewHandle<T>> for WeakViewHandle<T> {
3993    fn eq(&self, other: &ViewHandle<T>) -> bool {
3994        self.window_id == other.window_id && self.view_id == other.view_id
3995    }
3996}
3997
3998impl<T> Eq for ViewHandle<T> {}
3999
4000impl<T> Hash for ViewHandle<T> {
4001    fn hash<H: Hasher>(&self, state: &mut H) {
4002        self.window_id.hash(state);
4003        self.view_id.hash(state);
4004    }
4005}
4006
4007impl<T> Debug for ViewHandle<T> {
4008    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4009        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
4010            .field("window_id", &self.window_id)
4011            .field("view_id", &self.view_id)
4012            .finish()
4013    }
4014}
4015
4016impl<T: View> Handle<T> for ViewHandle<T> {
4017    type Weak = WeakViewHandle<T>;
4018
4019    fn id(&self) -> usize {
4020        self.view_id
4021    }
4022
4023    fn location(&self) -> EntityLocation {
4024        EntityLocation::View(self.window_id, self.view_id)
4025    }
4026
4027    fn downgrade(&self) -> Self::Weak {
4028        self.downgrade()
4029    }
4030
4031    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
4032    where
4033        Self: Sized,
4034    {
4035        weak.upgrade(cx)
4036    }
4037}
4038
4039pub struct AnyViewHandle {
4040    window_id: usize,
4041    view_id: usize,
4042    view_type: TypeId,
4043    ref_counts: Arc<Mutex<RefCounts>>,
4044
4045    #[cfg(any(test, feature = "test-support"))]
4046    handle_id: usize,
4047}
4048
4049impl AnyViewHandle {
4050    fn new(
4051        window_id: usize,
4052        view_id: usize,
4053        view_type: TypeId,
4054        ref_counts: Arc<Mutex<RefCounts>>,
4055    ) -> Self {
4056        ref_counts.lock().inc_view(window_id, view_id);
4057
4058        #[cfg(any(test, feature = "test-support"))]
4059        let handle_id = ref_counts
4060            .lock()
4061            .leak_detector
4062            .lock()
4063            .handle_created(None, view_id);
4064
4065        Self {
4066            window_id,
4067            view_id,
4068            view_type,
4069            ref_counts,
4070            #[cfg(any(test, feature = "test-support"))]
4071            handle_id,
4072        }
4073    }
4074
4075    pub fn window_id(&self) -> usize {
4076        self.window_id
4077    }
4078
4079    pub fn id(&self) -> usize {
4080        self.view_id
4081    }
4082
4083    pub fn is<T: 'static>(&self) -> bool {
4084        TypeId::of::<T>() == self.view_type
4085    }
4086
4087    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
4088        if self.is::<T>() {
4089            Some(ViewHandle {
4090                any_handle: self,
4091                view_type: PhantomData,
4092            })
4093        } else {
4094            None
4095        }
4096    }
4097
4098    pub fn downcast_ref<T: View>(&self) -> Option<&ViewHandle<T>> {
4099        if self.is::<T>() {
4100            Some(unsafe { mem::transmute(self) })
4101        } else {
4102            None
4103        }
4104    }
4105
4106    pub fn downgrade(&self) -> AnyWeakViewHandle {
4107        AnyWeakViewHandle {
4108            window_id: self.window_id,
4109            view_id: self.view_id,
4110            view_type: self.view_type,
4111        }
4112    }
4113
4114    pub fn view_type(&self) -> TypeId {
4115        self.view_type
4116    }
4117
4118    pub fn debug_json<'a, 'b>(&self, cx: &'b WindowContext<'a>) -> serde_json::Value {
4119        cx.views
4120            .get(&(self.window_id, self.view_id))
4121            .map_or_else(|| serde_json::Value::Null, |view| view.debug_json(cx))
4122    }
4123}
4124
4125impl Clone for AnyViewHandle {
4126    fn clone(&self) -> Self {
4127        Self::new(
4128            self.window_id,
4129            self.view_id,
4130            self.view_type,
4131            self.ref_counts.clone(),
4132        )
4133    }
4134}
4135
4136impl PartialEq for AnyViewHandle {
4137    fn eq(&self, other: &Self) -> bool {
4138        self.window_id == other.window_id && self.view_id == other.view_id
4139    }
4140}
4141
4142impl<T> PartialEq<ViewHandle<T>> for AnyViewHandle {
4143    fn eq(&self, other: &ViewHandle<T>) -> bool {
4144        self.window_id == other.window_id && self.view_id == other.view_id
4145    }
4146}
4147
4148impl Drop for AnyViewHandle {
4149    fn drop(&mut self) {
4150        self.ref_counts
4151            .lock()
4152            .dec_view(self.window_id, self.view_id);
4153        #[cfg(any(test, feature = "test-support"))]
4154        self.ref_counts
4155            .lock()
4156            .leak_detector
4157            .lock()
4158            .handle_dropped(self.view_id, self.handle_id);
4159    }
4160}
4161
4162impl Debug for AnyViewHandle {
4163    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4164        f.debug_struct("AnyViewHandle")
4165            .field("window_id", &self.window_id)
4166            .field("view_id", &self.view_id)
4167            .finish()
4168    }
4169}
4170
4171pub struct AnyModelHandle {
4172    model_id: usize,
4173    model_type: TypeId,
4174    ref_counts: Arc<Mutex<RefCounts>>,
4175
4176    #[cfg(any(test, feature = "test-support"))]
4177    handle_id: usize,
4178}
4179
4180impl AnyModelHandle {
4181    fn new(model_id: usize, model_type: TypeId, ref_counts: Arc<Mutex<RefCounts>>) -> Self {
4182        ref_counts.lock().inc_model(model_id);
4183
4184        #[cfg(any(test, feature = "test-support"))]
4185        let handle_id = ref_counts
4186            .lock()
4187            .leak_detector
4188            .lock()
4189            .handle_created(None, model_id);
4190
4191        Self {
4192            model_id,
4193            model_type,
4194            ref_counts,
4195
4196            #[cfg(any(test, feature = "test-support"))]
4197            handle_id,
4198        }
4199    }
4200
4201    pub fn downcast<T: Entity>(self) -> Option<ModelHandle<T>> {
4202        if self.is::<T>() {
4203            Some(ModelHandle {
4204                any_handle: self,
4205                model_type: PhantomData,
4206            })
4207        } else {
4208            None
4209        }
4210    }
4211
4212    pub fn downgrade(&self) -> AnyWeakModelHandle {
4213        AnyWeakModelHandle {
4214            model_id: self.model_id,
4215            model_type: self.model_type,
4216        }
4217    }
4218
4219    pub fn is<T: Entity>(&self) -> bool {
4220        self.model_type == TypeId::of::<T>()
4221    }
4222
4223    pub fn model_type(&self) -> TypeId {
4224        self.model_type
4225    }
4226}
4227
4228impl Clone for AnyModelHandle {
4229    fn clone(&self) -> Self {
4230        Self::new(self.model_id, self.model_type, self.ref_counts.clone())
4231    }
4232}
4233
4234impl Drop for AnyModelHandle {
4235    fn drop(&mut self) {
4236        let mut ref_counts = self.ref_counts.lock();
4237        ref_counts.dec_model(self.model_id);
4238
4239        #[cfg(any(test, feature = "test-support"))]
4240        ref_counts
4241            .leak_detector
4242            .lock()
4243            .handle_dropped(self.model_id, self.handle_id);
4244    }
4245}
4246
4247#[derive(Hash, PartialEq, Eq, Debug, Clone, Copy)]
4248pub struct AnyWeakModelHandle {
4249    model_id: usize,
4250    model_type: TypeId,
4251}
4252
4253impl AnyWeakModelHandle {
4254    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<AnyModelHandle> {
4255        cx.read_with(|cx| cx.upgrade_any_model_handle(self))
4256    }
4257
4258    pub fn model_type(&self) -> TypeId {
4259        self.model_type
4260    }
4261
4262    fn is<T: 'static>(&self) -> bool {
4263        TypeId::of::<T>() == self.model_type
4264    }
4265
4266    pub fn downcast<T: Entity>(self) -> Option<WeakModelHandle<T>> {
4267        if self.is::<T>() {
4268            let result = Some(WeakModelHandle {
4269                any_handle: self,
4270                model_type: PhantomData,
4271            });
4272
4273            result
4274        } else {
4275            None
4276        }
4277    }
4278}
4279
4280#[derive(Copy)]
4281pub struct WeakViewHandle<T> {
4282    any_handle: AnyWeakViewHandle,
4283    view_type: PhantomData<T>,
4284}
4285
4286impl<T> Debug for WeakViewHandle<T> {
4287    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4288        f.debug_struct(&format!("WeakViewHandle<{}>", type_name::<T>()))
4289            .field("any_handle", &self.any_handle)
4290            .finish()
4291    }
4292}
4293
4294impl<T> WeakHandle for WeakViewHandle<T> {
4295    fn id(&self) -> usize {
4296        self.view_id
4297    }
4298}
4299
4300impl<V: View> WeakViewHandle<V> {
4301    fn new(window_id: usize, view_id: usize) -> Self {
4302        Self {
4303            any_handle: AnyWeakViewHandle {
4304                window_id,
4305                view_id,
4306                view_type: TypeId::of::<V>(),
4307            },
4308            view_type: PhantomData,
4309        }
4310    }
4311
4312    pub fn id(&self) -> usize {
4313        self.view_id
4314    }
4315
4316    pub fn window_id(&self) -> usize {
4317        self.window_id
4318    }
4319
4320    pub fn into_any(self) -> AnyWeakViewHandle {
4321        self.any_handle
4322    }
4323
4324    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<ViewHandle<V>> {
4325        cx.read_with(|cx| cx.upgrade_view_handle(self))
4326    }
4327
4328    pub fn read_with<T>(
4329        &self,
4330        cx: &AsyncAppContext,
4331        read: impl FnOnce(&V, &ViewContext<V>) -> T,
4332    ) -> Result<T> {
4333        cx.read(|cx| {
4334            let handle = cx
4335                .upgrade_view_handle(self)
4336                .ok_or_else(|| anyhow!("view {} was dropped", V::ui_name()))?;
4337            cx.read_window(self.window_id, |cx| handle.read_with(cx, read))
4338                .ok_or_else(|| anyhow!("window was removed"))
4339        })
4340    }
4341
4342    pub fn update<T>(
4343        &self,
4344        cx: &mut AsyncAppContext,
4345        update: impl FnOnce(&mut V, &mut ViewContext<V>) -> T,
4346    ) -> Result<T> {
4347        cx.update(|cx| {
4348            let handle = cx
4349                .upgrade_view_handle(self)
4350                .ok_or_else(|| anyhow!("view {} was dropped", V::ui_name()))?;
4351            cx.update_window(self.window_id, |cx| handle.update(cx, update))
4352                .ok_or_else(|| anyhow!("window was removed"))
4353        })
4354    }
4355}
4356
4357impl<T> Deref for WeakViewHandle<T> {
4358    type Target = AnyWeakViewHandle;
4359
4360    fn deref(&self) -> &Self::Target {
4361        &self.any_handle
4362    }
4363}
4364
4365impl<T> Clone for WeakViewHandle<T> {
4366    fn clone(&self) -> Self {
4367        Self {
4368            any_handle: self.any_handle.clone(),
4369            view_type: PhantomData,
4370        }
4371    }
4372}
4373
4374impl<T> PartialEq for WeakViewHandle<T> {
4375    fn eq(&self, other: &Self) -> bool {
4376        self.window_id == other.window_id && self.view_id == other.view_id
4377    }
4378}
4379
4380impl<T> Eq for WeakViewHandle<T> {}
4381
4382impl<T> Hash for WeakViewHandle<T> {
4383    fn hash<H: Hasher>(&self, state: &mut H) {
4384        self.any_handle.hash(state);
4385    }
4386}
4387
4388#[derive(Debug, Clone, Copy, Eq, PartialEq)]
4389pub struct AnyWeakViewHandle {
4390    window_id: usize,
4391    view_id: usize,
4392    view_type: TypeId,
4393}
4394
4395impl AnyWeakViewHandle {
4396    pub fn id(&self) -> usize {
4397        self.view_id
4398    }
4399
4400    fn is<T: 'static>(&self) -> bool {
4401        TypeId::of::<T>() == self.view_type
4402    }
4403
4404    pub fn upgrade(&self, cx: &impl BorrowAppContext) -> Option<AnyViewHandle> {
4405        cx.read_with(|cx| cx.upgrade_any_view_handle(self))
4406    }
4407
4408    pub fn downcast<T: View>(self) -> Option<WeakViewHandle<T>> {
4409        if self.is::<T>() {
4410            Some(WeakViewHandle {
4411                any_handle: self,
4412                view_type: PhantomData,
4413            })
4414        } else {
4415            None
4416        }
4417    }
4418}
4419
4420impl Hash for AnyWeakViewHandle {
4421    fn hash<H: Hasher>(&self, state: &mut H) {
4422        self.window_id.hash(state);
4423        self.view_id.hash(state);
4424        self.view_type.hash(state);
4425    }
4426}
4427
4428#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
4429pub struct ElementStateId {
4430    view_id: usize,
4431    element_id: usize,
4432    tag: TypeId,
4433}
4434
4435pub struct ElementStateHandle<T> {
4436    value_type: PhantomData<T>,
4437    id: ElementStateId,
4438    ref_counts: Weak<Mutex<RefCounts>>,
4439}
4440
4441impl<T: 'static> ElementStateHandle<T> {
4442    fn new(id: ElementStateId, frame_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
4443        ref_counts.lock().inc_element_state(id, frame_id);
4444        Self {
4445            value_type: PhantomData,
4446            id,
4447            ref_counts: Arc::downgrade(ref_counts),
4448        }
4449    }
4450
4451    pub fn id(&self) -> ElementStateId {
4452        self.id
4453    }
4454
4455    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
4456        cx.element_states
4457            .get(&self.id)
4458            .unwrap()
4459            .downcast_ref()
4460            .unwrap()
4461    }
4462
4463    pub fn update<C, D, R>(&self, cx: &mut C, f: impl FnOnce(&mut T, &mut C) -> R) -> R
4464    where
4465        C: DerefMut<Target = D>,
4466        D: DerefMut<Target = AppContext>,
4467    {
4468        let mut element_state = cx.deref_mut().element_states.remove(&self.id).unwrap();
4469        let result = f(element_state.downcast_mut().unwrap(), cx);
4470        cx.deref_mut().element_states.insert(self.id, element_state);
4471        result
4472    }
4473}
4474
4475impl<T> Drop for ElementStateHandle<T> {
4476    fn drop(&mut self) {
4477        if let Some(ref_counts) = self.ref_counts.upgrade() {
4478            ref_counts.lock().dec_element_state(self.id);
4479        }
4480    }
4481}
4482
4483#[must_use]
4484pub enum Subscription {
4485    Subscription(callback_collection::Subscription<usize, SubscriptionCallback>),
4486    Observation(callback_collection::Subscription<usize, ObservationCallback>),
4487    GlobalSubscription(callback_collection::Subscription<TypeId, GlobalSubscriptionCallback>),
4488    GlobalObservation(callback_collection::Subscription<TypeId, GlobalObservationCallback>),
4489    FocusObservation(callback_collection::Subscription<usize, FocusObservationCallback>),
4490    WindowActivationObservation(callback_collection::Subscription<usize, WindowActivationCallback>),
4491    WindowFullscreenObservation(callback_collection::Subscription<usize, WindowFullscreenCallback>),
4492    WindowBoundsObservation(callback_collection::Subscription<usize, WindowBoundsCallback>),
4493    KeystrokeObservation(callback_collection::Subscription<usize, KeystrokeCallback>),
4494    ReleaseObservation(callback_collection::Subscription<usize, ReleaseObservationCallback>),
4495    ActionObservation(callback_collection::Subscription<(), ActionObservationCallback>),
4496    ActiveLabeledTasksObservation(
4497        callback_collection::Subscription<(), ActiveLabeledTasksCallback>,
4498    ),
4499}
4500
4501impl Subscription {
4502    pub fn id(&self) -> usize {
4503        match self {
4504            Subscription::Subscription(subscription) => subscription.id(),
4505            Subscription::Observation(subscription) => subscription.id(),
4506            Subscription::GlobalSubscription(subscription) => subscription.id(),
4507            Subscription::GlobalObservation(subscription) => subscription.id(),
4508            Subscription::FocusObservation(subscription) => subscription.id(),
4509            Subscription::WindowActivationObservation(subscription) => subscription.id(),
4510            Subscription::WindowFullscreenObservation(subscription) => subscription.id(),
4511            Subscription::WindowBoundsObservation(subscription) => subscription.id(),
4512            Subscription::KeystrokeObservation(subscription) => subscription.id(),
4513            Subscription::ReleaseObservation(subscription) => subscription.id(),
4514            Subscription::ActionObservation(subscription) => subscription.id(),
4515            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.id(),
4516        }
4517    }
4518
4519    pub fn detach(&mut self) {
4520        match self {
4521            Subscription::Subscription(subscription) => subscription.detach(),
4522            Subscription::GlobalSubscription(subscription) => subscription.detach(),
4523            Subscription::Observation(subscription) => subscription.detach(),
4524            Subscription::GlobalObservation(subscription) => subscription.detach(),
4525            Subscription::FocusObservation(subscription) => subscription.detach(),
4526            Subscription::KeystrokeObservation(subscription) => subscription.detach(),
4527            Subscription::WindowActivationObservation(subscription) => subscription.detach(),
4528            Subscription::WindowFullscreenObservation(subscription) => subscription.detach(),
4529            Subscription::WindowBoundsObservation(subscription) => subscription.detach(),
4530            Subscription::ReleaseObservation(subscription) => subscription.detach(),
4531            Subscription::ActionObservation(subscription) => subscription.detach(),
4532            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.detach(),
4533        }
4534    }
4535}
4536
4537#[cfg(test)]
4538mod tests {
4539    use super::*;
4540    use crate::{
4541        actions,
4542        elements::*,
4543        impl_actions,
4544        platform::{MouseButton, MouseButtonEvent},
4545        window::ChildView,
4546    };
4547    use itertools::Itertools;
4548    use postage::{sink::Sink, stream::Stream};
4549    use serde::Deserialize;
4550    use smol::future::poll_once;
4551    use std::{
4552        cell::Cell,
4553        sync::atomic::{AtomicBool, AtomicUsize, Ordering::SeqCst},
4554    };
4555
4556    #[crate::test(self)]
4557    fn test_model_handles(cx: &mut AppContext) {
4558        struct Model {
4559            other: Option<ModelHandle<Model>>,
4560            events: Vec<String>,
4561        }
4562
4563        impl Entity for Model {
4564            type Event = usize;
4565        }
4566
4567        impl Model {
4568            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
4569                if let Some(other) = other.as_ref() {
4570                    cx.observe(other, |me, _, _| {
4571                        me.events.push("notified".into());
4572                    })
4573                    .detach();
4574                    cx.subscribe(other, |me, _, event, _| {
4575                        me.events.push(format!("observed event {}", event));
4576                    })
4577                    .detach();
4578                }
4579
4580                Self {
4581                    other,
4582                    events: Vec::new(),
4583                }
4584            }
4585        }
4586
4587        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
4588        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
4589        assert_eq!(cx.models.len(), 2);
4590
4591        handle_1.update(cx, |model, cx| {
4592            model.events.push("updated".into());
4593            cx.emit(1);
4594            cx.notify();
4595            cx.emit(2);
4596        });
4597        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
4598        assert_eq!(
4599            handle_2.read(cx).events,
4600            vec![
4601                "observed event 1".to_string(),
4602                "notified".to_string(),
4603                "observed event 2".to_string(),
4604            ]
4605        );
4606
4607        handle_2.update(cx, |model, _| {
4608            drop(handle_1);
4609            model.other.take();
4610        });
4611
4612        assert_eq!(cx.models.len(), 1);
4613        assert!(cx.subscriptions.is_empty());
4614        assert!(cx.observations.is_empty());
4615    }
4616
4617    #[crate::test(self)]
4618    fn test_model_events(cx: &mut AppContext) {
4619        #[derive(Default)]
4620        struct Model {
4621            events: Vec<usize>,
4622        }
4623
4624        impl Entity for Model {
4625            type Event = usize;
4626        }
4627
4628        let handle_1 = cx.add_model(|_| Model::default());
4629        let handle_2 = cx.add_model(|_| Model::default());
4630
4631        handle_1.update(cx, |_, cx| {
4632            cx.subscribe(&handle_2, move |model: &mut Model, emitter, event, cx| {
4633                model.events.push(*event);
4634
4635                cx.subscribe(&emitter, |model, _, event, _| {
4636                    model.events.push(*event * 2);
4637                })
4638                .detach();
4639            })
4640            .detach();
4641        });
4642
4643        handle_2.update(cx, |_, c| c.emit(7));
4644        assert_eq!(handle_1.read(cx).events, vec![7]);
4645
4646        handle_2.update(cx, |_, c| c.emit(5));
4647        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
4648    }
4649
4650    #[crate::test(self)]
4651    fn test_model_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
4652        #[derive(Default)]
4653        struct Model;
4654
4655        impl Entity for Model {
4656            type Event = ();
4657        }
4658
4659        let events = Rc::new(RefCell::new(Vec::new()));
4660        cx.add_model(|cx| {
4661            drop(cx.subscribe(&cx.handle(), {
4662                let events = events.clone();
4663                move |_, _, _, _| events.borrow_mut().push("dropped before flush")
4664            }));
4665            cx.subscribe(&cx.handle(), {
4666                let events = events.clone();
4667                move |_, _, _, _| events.borrow_mut().push("before emit")
4668            })
4669            .detach();
4670            cx.emit(());
4671            cx.subscribe(&cx.handle(), {
4672                let events = events.clone();
4673                move |_, _, _, _| events.borrow_mut().push("after emit")
4674            })
4675            .detach();
4676            Model
4677        });
4678        assert_eq!(*events.borrow(), ["before emit"]);
4679    }
4680
4681    #[crate::test(self)]
4682    fn test_observe_and_notify_from_model(cx: &mut AppContext) {
4683        #[derive(Default)]
4684        struct Model {
4685            count: usize,
4686            events: Vec<usize>,
4687        }
4688
4689        impl Entity for Model {
4690            type Event = ();
4691        }
4692
4693        let handle_1 = cx.add_model(|_| Model::default());
4694        let handle_2 = cx.add_model(|_| Model::default());
4695
4696        handle_1.update(cx, |_, c| {
4697            c.observe(&handle_2, move |model, observed, c| {
4698                model.events.push(observed.read(c).count);
4699                c.observe(&observed, |model, observed, c| {
4700                    model.events.push(observed.read(c).count * 2);
4701                })
4702                .detach();
4703            })
4704            .detach();
4705        });
4706
4707        handle_2.update(cx, |model, c| {
4708            model.count = 7;
4709            c.notify()
4710        });
4711        assert_eq!(handle_1.read(cx).events, vec![7]);
4712
4713        handle_2.update(cx, |model, c| {
4714            model.count = 5;
4715            c.notify()
4716        });
4717        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10])
4718    }
4719
4720    #[crate::test(self)]
4721    fn test_model_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
4722        #[derive(Default)]
4723        struct Model;
4724
4725        impl Entity for Model {
4726            type Event = ();
4727        }
4728
4729        let events = Rc::new(RefCell::new(Vec::new()));
4730        cx.add_model(|cx| {
4731            drop(cx.observe(&cx.handle(), {
4732                let events = events.clone();
4733                move |_, _, _| events.borrow_mut().push("dropped before flush")
4734            }));
4735            cx.observe(&cx.handle(), {
4736                let events = events.clone();
4737                move |_, _, _| events.borrow_mut().push("before notify")
4738            })
4739            .detach();
4740            cx.notify();
4741            cx.observe(&cx.handle(), {
4742                let events = events.clone();
4743                move |_, _, _| events.borrow_mut().push("after notify")
4744            })
4745            .detach();
4746            Model
4747        });
4748        assert_eq!(*events.borrow(), ["before notify"]);
4749    }
4750
4751    #[crate::test(self)]
4752    fn test_defer_and_after_window_update(cx: &mut TestAppContext) {
4753        struct View {
4754            render_count: usize,
4755        }
4756
4757        impl Entity for View {
4758            type Event = usize;
4759        }
4760
4761        impl super::View for View {
4762            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4763                post_inc(&mut self.render_count);
4764                Empty::new().into_any()
4765            }
4766
4767            fn ui_name() -> &'static str {
4768                "View"
4769            }
4770        }
4771
4772        let (_, view) = cx.add_window(|_| View { render_count: 0 });
4773        let called_defer = Rc::new(AtomicBool::new(false));
4774        let called_after_window_update = Rc::new(AtomicBool::new(false));
4775
4776        view.update(cx, |this, cx| {
4777            assert_eq!(this.render_count, 1);
4778            cx.defer({
4779                let called_defer = called_defer.clone();
4780                move |this, _| {
4781                    assert_eq!(this.render_count, 1);
4782                    called_defer.store(true, SeqCst);
4783                }
4784            });
4785            cx.after_window_update({
4786                let called_after_window_update = called_after_window_update.clone();
4787                move |this, cx| {
4788                    assert_eq!(this.render_count, 2);
4789                    called_after_window_update.store(true, SeqCst);
4790                    cx.notify();
4791                }
4792            });
4793            assert!(!called_defer.load(SeqCst));
4794            assert!(!called_after_window_update.load(SeqCst));
4795            cx.notify();
4796        });
4797
4798        assert!(called_defer.load(SeqCst));
4799        assert!(called_after_window_update.load(SeqCst));
4800        assert_eq!(view.read_with(cx, |view, _| view.render_count), 3);
4801    }
4802
4803    #[crate::test(self)]
4804    fn test_view_handles(cx: &mut TestAppContext) {
4805        struct View {
4806            other: Option<ViewHandle<View>>,
4807            events: Vec<String>,
4808        }
4809
4810        impl Entity for View {
4811            type Event = usize;
4812        }
4813
4814        impl super::View for View {
4815            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4816                Empty::new().into_any()
4817            }
4818
4819            fn ui_name() -> &'static str {
4820                "View"
4821            }
4822        }
4823
4824        impl View {
4825            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
4826                if let Some(other) = other.as_ref() {
4827                    cx.subscribe(other, |me, _, event, _| {
4828                        me.events.push(format!("observed event {}", event));
4829                    })
4830                    .detach();
4831                }
4832                Self {
4833                    other,
4834                    events: Vec::new(),
4835                }
4836            }
4837        }
4838
4839        let (window_id, _root_view) = cx.add_window(|cx| View::new(None, cx));
4840        let handle_1 = cx.add_view(window_id, |cx| View::new(None, cx));
4841        let handle_2 = cx.add_view(window_id, |cx| View::new(Some(handle_1.clone()), cx));
4842        assert_eq!(cx.read(|cx| cx.views.len()), 3);
4843
4844        handle_1.update(cx, |view, cx| {
4845            view.events.push("updated".into());
4846            cx.emit(1);
4847            cx.emit(2);
4848        });
4849        handle_1.read_with(cx, |view, _| {
4850            assert_eq!(view.events, vec!["updated".to_string()]);
4851        });
4852        handle_2.read_with(cx, |view, _| {
4853            assert_eq!(
4854                view.events,
4855                vec![
4856                    "observed event 1".to_string(),
4857                    "observed event 2".to_string(),
4858                ]
4859            );
4860        });
4861
4862        handle_2.update(cx, |view, _| {
4863            drop(handle_1);
4864            view.other.take();
4865        });
4866
4867        cx.read(|cx| {
4868            assert_eq!(cx.views.len(), 2);
4869            assert!(cx.subscriptions.is_empty());
4870            assert!(cx.observations.is_empty());
4871        });
4872    }
4873
4874    #[crate::test(self)]
4875    fn test_add_window(cx: &mut AppContext) {
4876        struct View {
4877            mouse_down_count: Arc<AtomicUsize>,
4878        }
4879
4880        impl Entity for View {
4881            type Event = ();
4882        }
4883
4884        impl super::View for View {
4885            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
4886                enum Handler {}
4887                let mouse_down_count = self.mouse_down_count.clone();
4888                MouseEventHandler::<Handler, _>::new(0, cx, |_, _| Empty::new())
4889                    .on_down(MouseButton::Left, move |_, _, _| {
4890                        mouse_down_count.fetch_add(1, SeqCst);
4891                    })
4892                    .into_any()
4893            }
4894
4895            fn ui_name() -> &'static str {
4896                "View"
4897            }
4898        }
4899
4900        let mouse_down_count = Arc::new(AtomicUsize::new(0));
4901        let (window_id, _) = cx.add_window(Default::default(), |_| View {
4902            mouse_down_count: mouse_down_count.clone(),
4903        });
4904
4905        cx.update_window(window_id, |cx| {
4906            // Ensure window's root element is in a valid lifecycle state.
4907            cx.dispatch_event(
4908                Event::MouseDown(MouseButtonEvent {
4909                    position: Default::default(),
4910                    button: MouseButton::Left,
4911                    modifiers: Default::default(),
4912                    click_count: 1,
4913                }),
4914                false,
4915            );
4916            assert_eq!(mouse_down_count.load(SeqCst), 1);
4917        });
4918    }
4919
4920    #[crate::test(self)]
4921    fn test_entity_release_hooks(cx: &mut AppContext) {
4922        struct Model {
4923            released: Rc<Cell<bool>>,
4924        }
4925
4926        struct View {
4927            released: Rc<Cell<bool>>,
4928        }
4929
4930        impl Entity for Model {
4931            type Event = ();
4932
4933            fn release(&mut self, _: &mut AppContext) {
4934                self.released.set(true);
4935            }
4936        }
4937
4938        impl Entity for View {
4939            type Event = ();
4940
4941            fn release(&mut self, _: &mut AppContext) {
4942                self.released.set(true);
4943            }
4944        }
4945
4946        impl super::View for View {
4947            fn ui_name() -> &'static str {
4948                "View"
4949            }
4950
4951            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
4952                Empty::new().into_any()
4953            }
4954        }
4955
4956        let model_released = Rc::new(Cell::new(false));
4957        let model_release_observed = Rc::new(Cell::new(false));
4958        let view_released = Rc::new(Cell::new(false));
4959        let view_release_observed = Rc::new(Cell::new(false));
4960
4961        let model = cx.add_model(|_| Model {
4962            released: model_released.clone(),
4963        });
4964        let (window_id, view) = cx.add_window(Default::default(), |_| View {
4965            released: view_released.clone(),
4966        });
4967        assert!(!model_released.get());
4968        assert!(!view_released.get());
4969
4970        cx.observe_release(&model, {
4971            let model_release_observed = model_release_observed.clone();
4972            move |_, _| model_release_observed.set(true)
4973        })
4974        .detach();
4975        cx.observe_release(&view, {
4976            let view_release_observed = view_release_observed.clone();
4977            move |_, _| view_release_observed.set(true)
4978        })
4979        .detach();
4980
4981        cx.update(move |_| {
4982            drop(model);
4983        });
4984        assert!(model_released.get());
4985        assert!(model_release_observed.get());
4986
4987        drop(view);
4988        cx.update_window(window_id, |cx| cx.remove_window());
4989        assert!(view_released.get());
4990        assert!(view_release_observed.get());
4991    }
4992
4993    #[crate::test(self)]
4994    fn test_view_events(cx: &mut TestAppContext) {
4995        struct Model;
4996
4997        impl Entity for Model {
4998            type Event = String;
4999        }
5000
5001        let (window_id, handle_1) = cx.add_window(|_| TestView::default());
5002        let handle_2 = cx.add_view(window_id, |_| TestView::default());
5003        let handle_3 = cx.add_model(|_| Model);
5004
5005        handle_1.update(cx, |_, cx| {
5006            cx.subscribe(&handle_2, move |me, emitter, event, cx| {
5007                me.events.push(event.clone());
5008
5009                cx.subscribe(&emitter, |me, _, event, _| {
5010                    me.events.push(format!("{event} from inner"));
5011                })
5012                .detach();
5013            })
5014            .detach();
5015
5016            cx.subscribe(&handle_3, |me, _, event, _| {
5017                me.events.push(event.clone());
5018            })
5019            .detach();
5020        });
5021
5022        handle_2.update(cx, |_, c| c.emit("7".into()));
5023        handle_1.read_with(cx, |view, _| assert_eq!(view.events, ["7"]));
5024
5025        handle_2.update(cx, |_, c| c.emit("5".into()));
5026        handle_1.read_with(cx, |view, _| {
5027            assert_eq!(view.events, ["7", "5", "5 from inner"])
5028        });
5029
5030        handle_3.update(cx, |_, c| c.emit("9".into()));
5031        handle_1.read_with(cx, |view, _| {
5032            assert_eq!(view.events, ["7", "5", "5 from inner", "9"])
5033        });
5034    }
5035
5036    #[crate::test(self)]
5037    fn test_global_events(cx: &mut AppContext) {
5038        #[derive(Clone, Debug, Eq, PartialEq)]
5039        struct GlobalEvent(u64);
5040
5041        let events = Rc::new(RefCell::new(Vec::new()));
5042        let first_subscription;
5043        let second_subscription;
5044
5045        {
5046            let events = events.clone();
5047            first_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
5048                events.borrow_mut().push(("First", e.clone()));
5049            });
5050        }
5051
5052        {
5053            let events = events.clone();
5054            second_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
5055                events.borrow_mut().push(("Second", e.clone()));
5056            });
5057        }
5058
5059        cx.update(|cx| {
5060            cx.emit_global(GlobalEvent(1));
5061            cx.emit_global(GlobalEvent(2));
5062        });
5063
5064        drop(first_subscription);
5065
5066        cx.update(|cx| {
5067            cx.emit_global(GlobalEvent(3));
5068        });
5069
5070        drop(second_subscription);
5071
5072        cx.update(|cx| {
5073            cx.emit_global(GlobalEvent(4));
5074        });
5075
5076        assert_eq!(
5077            &*events.borrow(),
5078            &[
5079                ("First", GlobalEvent(1)),
5080                ("Second", GlobalEvent(1)),
5081                ("First", GlobalEvent(2)),
5082                ("Second", GlobalEvent(2)),
5083                ("Second", GlobalEvent(3)),
5084            ]
5085        );
5086    }
5087
5088    #[crate::test(self)]
5089    fn test_global_events_emitted_before_subscription_in_same_update_cycle(cx: &mut AppContext) {
5090        let events = Rc::new(RefCell::new(Vec::new()));
5091        cx.update(|cx| {
5092            {
5093                let events = events.clone();
5094                drop(cx.subscribe_global(move |_: &(), _| {
5095                    events.borrow_mut().push("dropped before emit");
5096                }));
5097            }
5098
5099            {
5100                let events = events.clone();
5101                cx.subscribe_global(move |_: &(), _| {
5102                    events.borrow_mut().push("before emit");
5103                })
5104                .detach();
5105            }
5106
5107            cx.emit_global(());
5108
5109            {
5110                let events = events.clone();
5111                cx.subscribe_global(move |_: &(), _| {
5112                    events.borrow_mut().push("after emit");
5113                })
5114                .detach();
5115            }
5116        });
5117
5118        assert_eq!(*events.borrow(), ["before emit"]);
5119    }
5120
5121    #[crate::test(self)]
5122    fn test_global_nested_events(cx: &mut AppContext) {
5123        #[derive(Clone, Debug, Eq, PartialEq)]
5124        struct GlobalEvent(u64);
5125
5126        let events = Rc::new(RefCell::new(Vec::new()));
5127
5128        {
5129            let events = events.clone();
5130            cx.subscribe_global(move |e: &GlobalEvent, cx| {
5131                events.borrow_mut().push(("Outer", e.clone()));
5132
5133                if e.0 == 1 {
5134                    let events = events.clone();
5135                    cx.subscribe_global(move |e: &GlobalEvent, _| {
5136                        events.borrow_mut().push(("Inner", e.clone()));
5137                    })
5138                    .detach();
5139                }
5140            })
5141            .detach();
5142        }
5143
5144        cx.update(|cx| {
5145            cx.emit_global(GlobalEvent(1));
5146            cx.emit_global(GlobalEvent(2));
5147            cx.emit_global(GlobalEvent(3));
5148        });
5149        cx.update(|cx| {
5150            cx.emit_global(GlobalEvent(4));
5151        });
5152
5153        assert_eq!(
5154            &*events.borrow(),
5155            &[
5156                ("Outer", GlobalEvent(1)),
5157                ("Outer", GlobalEvent(2)),
5158                ("Outer", GlobalEvent(3)),
5159                ("Outer", GlobalEvent(4)),
5160                ("Inner", GlobalEvent(4)),
5161            ]
5162        );
5163    }
5164
5165    #[crate::test(self)]
5166    fn test_global(cx: &mut AppContext) {
5167        type Global = usize;
5168
5169        let observation_count = Rc::new(RefCell::new(0));
5170        let subscription = cx.observe_global::<Global, _>({
5171            let observation_count = observation_count.clone();
5172            move |_| {
5173                *observation_count.borrow_mut() += 1;
5174            }
5175        });
5176
5177        assert!(!cx.has_global::<Global>());
5178        assert_eq!(cx.default_global::<Global>(), &0);
5179        assert_eq!(*observation_count.borrow(), 1);
5180        assert!(cx.has_global::<Global>());
5181        assert_eq!(
5182            cx.update_global::<Global, _, _>(|global, _| {
5183                *global = 1;
5184                "Update Result"
5185            }),
5186            "Update Result"
5187        );
5188        assert_eq!(*observation_count.borrow(), 2);
5189        assert_eq!(cx.global::<Global>(), &1);
5190
5191        drop(subscription);
5192        cx.update_global::<Global, _, _>(|global, _| {
5193            *global = 2;
5194        });
5195        assert_eq!(*observation_count.borrow(), 2);
5196
5197        type OtherGlobal = f32;
5198
5199        let observation_count = Rc::new(RefCell::new(0));
5200        cx.observe_global::<OtherGlobal, _>({
5201            let observation_count = observation_count.clone();
5202            move |_| {
5203                *observation_count.borrow_mut() += 1;
5204            }
5205        })
5206        .detach();
5207
5208        assert_eq!(
5209            cx.update_default_global::<OtherGlobal, _, _>(|global, _| {
5210                assert_eq!(global, &0.0);
5211                *global = 2.0;
5212                "Default update result"
5213            }),
5214            "Default update result"
5215        );
5216        assert_eq!(cx.global::<OtherGlobal>(), &2.0);
5217        assert_eq!(*observation_count.borrow(), 1);
5218    }
5219
5220    #[crate::test(self)]
5221    fn test_dropping_subscribers(cx: &mut TestAppContext) {
5222        struct Model;
5223
5224        impl Entity for Model {
5225            type Event = ();
5226        }
5227
5228        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
5229        let observing_view = cx.add_view(window_id, |_| TestView::default());
5230        let emitting_view = cx.add_view(window_id, |_| TestView::default());
5231        let observing_model = cx.add_model(|_| Model);
5232        let observed_model = cx.add_model(|_| Model);
5233
5234        observing_view.update(cx, |_, cx| {
5235            cx.subscribe(&emitting_view, |_, _, _, _| {}).detach();
5236            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5237        });
5238        observing_model.update(cx, |_, cx| {
5239            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5240        });
5241
5242        cx.update(|_| {
5243            drop(observing_view);
5244            drop(observing_model);
5245        });
5246
5247        emitting_view.update(cx, |_, cx| cx.emit(Default::default()));
5248        observed_model.update(cx, |_, cx| cx.emit(()));
5249    }
5250
5251    #[crate::test(self)]
5252    fn test_view_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
5253        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5254            drop(cx.subscribe(&cx.handle(), {
5255                move |this, _, _, _| this.events.push("dropped before flush".into())
5256            }));
5257            cx.subscribe(&cx.handle(), {
5258                move |this, _, _, _| this.events.push("before emit".into())
5259            })
5260            .detach();
5261            cx.emit("the event".into());
5262            cx.subscribe(&cx.handle(), {
5263                move |this, _, _, _| this.events.push("after emit".into())
5264            })
5265            .detach();
5266            TestView { events: Vec::new() }
5267        });
5268
5269        assert_eq!(view.read(cx).events, ["before emit"]);
5270    }
5271
5272    #[crate::test(self)]
5273    fn test_observe_and_notify_from_view(cx: &mut TestAppContext) {
5274        #[derive(Default)]
5275        struct Model {
5276            state: String,
5277        }
5278
5279        impl Entity for Model {
5280            type Event = ();
5281        }
5282
5283        let (_, view) = cx.add_window(|_| TestView::default());
5284        let model = cx.add_model(|_| Model {
5285            state: "old-state".into(),
5286        });
5287
5288        view.update(cx, |_, c| {
5289            c.observe(&model, |me, observed, cx| {
5290                me.events.push(observed.read(cx).state.clone())
5291            })
5292            .detach();
5293        });
5294
5295        model.update(cx, |model, cx| {
5296            model.state = "new-state".into();
5297            cx.notify();
5298        });
5299        view.read_with(cx, |view, _| assert_eq!(view.events, ["new-state"]));
5300    }
5301
5302    #[crate::test(self)]
5303    fn test_view_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
5304        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5305            drop(cx.observe(&cx.handle(), {
5306                move |this, _, _| this.events.push("dropped before flush".into())
5307            }));
5308            cx.observe(&cx.handle(), {
5309                move |this, _, _| this.events.push("before notify".into())
5310            })
5311            .detach();
5312            cx.notify();
5313            cx.observe(&cx.handle(), {
5314                move |this, _, _| this.events.push("after notify".into())
5315            })
5316            .detach();
5317            TestView { events: Vec::new() }
5318        });
5319
5320        assert_eq!(view.read(cx).events, ["before notify"]);
5321    }
5322
5323    #[crate::test(self)]
5324    fn test_notify_and_drop_observe_subscription_in_same_update_cycle(cx: &mut TestAppContext) {
5325        struct Model;
5326        impl Entity for Model {
5327            type Event = ();
5328        }
5329
5330        let model = cx.add_model(|_| Model);
5331        let (_, view) = cx.add_window(|_| TestView::default());
5332
5333        view.update(cx, |_, cx| {
5334            model.update(cx, |_, cx| cx.notify());
5335            drop(cx.observe(&model, move |this, _, _| {
5336                this.events.push("model notified".into());
5337            }));
5338            model.update(cx, |_, cx| cx.notify());
5339        });
5340
5341        for _ in 0..3 {
5342            model.update(cx, |_, cx| cx.notify());
5343        }
5344        view.read_with(cx, |view, _| assert_eq!(view.events, Vec::<&str>::new()));
5345    }
5346
5347    #[crate::test(self)]
5348    fn test_dropping_observers(cx: &mut TestAppContext) {
5349        struct Model;
5350
5351        impl Entity for Model {
5352            type Event = ();
5353        }
5354
5355        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
5356        let observing_view = cx.add_view(window_id, |_| TestView::default());
5357        let observing_model = cx.add_model(|_| Model);
5358        let observed_model = cx.add_model(|_| Model);
5359
5360        observing_view.update(cx, |_, cx| {
5361            cx.observe(&observed_model, |_, _, _| {}).detach();
5362        });
5363        observing_model.update(cx, |_, cx| {
5364            cx.observe(&observed_model, |_, _, _| {}).detach();
5365        });
5366
5367        cx.update(|_| {
5368            drop(observing_view);
5369            drop(observing_model);
5370        });
5371
5372        observed_model.update(cx, |_, cx| cx.notify());
5373    }
5374
5375    #[crate::test(self)]
5376    fn test_dropping_subscriptions_during_callback(cx: &mut TestAppContext) {
5377        struct Model;
5378
5379        impl Entity for Model {
5380            type Event = u64;
5381        }
5382
5383        // Events
5384        let observing_model = cx.add_model(|_| Model);
5385        let observed_model = cx.add_model(|_| Model);
5386
5387        let events = Rc::new(RefCell::new(Vec::new()));
5388
5389        observing_model.update(cx, |_, cx| {
5390            let events = events.clone();
5391            let subscription = Rc::new(RefCell::new(None));
5392            *subscription.borrow_mut() = Some(cx.subscribe(&observed_model, {
5393                let subscription = subscription.clone();
5394                move |_, _, e, _| {
5395                    subscription.borrow_mut().take();
5396                    events.borrow_mut().push(*e);
5397                }
5398            }));
5399        });
5400
5401        observed_model.update(cx, |_, cx| {
5402            cx.emit(1);
5403            cx.emit(2);
5404        });
5405
5406        assert_eq!(*events.borrow(), [1]);
5407
5408        // Global Events
5409        #[derive(Clone, Debug, Eq, PartialEq)]
5410        struct GlobalEvent(u64);
5411
5412        let events = Rc::new(RefCell::new(Vec::new()));
5413
5414        {
5415            let events = events.clone();
5416            let subscription = Rc::new(RefCell::new(None));
5417            *subscription.borrow_mut() = Some(cx.subscribe_global({
5418                let subscription = subscription.clone();
5419                move |e: &GlobalEvent, _| {
5420                    subscription.borrow_mut().take();
5421                    events.borrow_mut().push(e.clone());
5422                }
5423            }));
5424        }
5425
5426        cx.update(|cx| {
5427            cx.emit_global(GlobalEvent(1));
5428            cx.emit_global(GlobalEvent(2));
5429        });
5430
5431        assert_eq!(*events.borrow(), [GlobalEvent(1)]);
5432
5433        // Model Observation
5434        let observing_model = cx.add_model(|_| Model);
5435        let observed_model = cx.add_model(|_| Model);
5436
5437        let observation_count = Rc::new(RefCell::new(0));
5438
5439        observing_model.update(cx, |_, cx| {
5440            let observation_count = observation_count.clone();
5441            let subscription = Rc::new(RefCell::new(None));
5442            *subscription.borrow_mut() = Some(cx.observe(&observed_model, {
5443                let subscription = subscription.clone();
5444                move |_, _, _| {
5445                    subscription.borrow_mut().take();
5446                    *observation_count.borrow_mut() += 1;
5447                }
5448            }));
5449        });
5450
5451        observed_model.update(cx, |_, cx| {
5452            cx.notify();
5453        });
5454
5455        observed_model.update(cx, |_, cx| {
5456            cx.notify();
5457        });
5458
5459        assert_eq!(*observation_count.borrow(), 1);
5460
5461        // View Observation
5462        struct View;
5463
5464        impl Entity for View {
5465            type Event = ();
5466        }
5467
5468        impl super::View for View {
5469            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
5470                Empty::new().into_any()
5471            }
5472
5473            fn ui_name() -> &'static str {
5474                "View"
5475            }
5476        }
5477
5478        let (window_id, _root_view) = cx.add_window(|_| View);
5479        let observing_view = cx.add_view(window_id, |_| View);
5480        let observed_view = cx.add_view(window_id, |_| View);
5481
5482        let observation_count = Rc::new(RefCell::new(0));
5483        observing_view.update(cx, |_, cx| {
5484            let observation_count = observation_count.clone();
5485            let subscription = Rc::new(RefCell::new(None));
5486            *subscription.borrow_mut() = Some(cx.observe(&observed_view, {
5487                let subscription = subscription.clone();
5488                move |_, _, _| {
5489                    subscription.borrow_mut().take();
5490                    *observation_count.borrow_mut() += 1;
5491                }
5492            }));
5493        });
5494
5495        observed_view.update(cx, |_, cx| {
5496            cx.notify();
5497        });
5498
5499        observed_view.update(cx, |_, cx| {
5500            cx.notify();
5501        });
5502
5503        assert_eq!(*observation_count.borrow(), 1);
5504
5505        // Global Observation
5506        let observation_count = Rc::new(RefCell::new(0));
5507        let subscription = Rc::new(RefCell::new(None));
5508        *subscription.borrow_mut() = Some(cx.observe_global::<(), _>({
5509            let observation_count = observation_count.clone();
5510            let subscription = subscription.clone();
5511            move |_| {
5512                subscription.borrow_mut().take();
5513                *observation_count.borrow_mut() += 1;
5514            }
5515        }));
5516
5517        cx.update(|cx| {
5518            cx.default_global::<()>();
5519            cx.set_global(());
5520        });
5521        assert_eq!(*observation_count.borrow(), 1);
5522    }
5523
5524    #[crate::test(self)]
5525    fn test_focus(cx: &mut TestAppContext) {
5526        struct View {
5527            name: String,
5528            events: Arc<Mutex<Vec<String>>>,
5529            child: Option<AnyViewHandle>,
5530        }
5531
5532        impl Entity for View {
5533            type Event = ();
5534        }
5535
5536        impl super::View for View {
5537            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5538                self.child
5539                    .as_ref()
5540                    .map(|child| ChildView::new(child, cx).into_any())
5541                    .unwrap_or(Empty::new().into_any())
5542            }
5543
5544            fn ui_name() -> &'static str {
5545                "View"
5546            }
5547
5548            fn focus_in(&mut self, focused: AnyViewHandle, cx: &mut ViewContext<Self>) {
5549                if cx.handle().id() == focused.id() {
5550                    self.events.lock().push(format!("{} focused", &self.name));
5551                }
5552            }
5553
5554            fn focus_out(&mut self, blurred: AnyViewHandle, cx: &mut ViewContext<Self>) {
5555                if cx.handle().id() == blurred.id() {
5556                    self.events.lock().push(format!("{} blurred", &self.name));
5557                }
5558            }
5559        }
5560
5561        let view_events: Arc<Mutex<Vec<String>>> = Default::default();
5562        let (window_id, view_1) = cx.add_window(|_| View {
5563            events: view_events.clone(),
5564            name: "view 1".to_string(),
5565            child: None,
5566        });
5567        let view_2 = cx
5568            .update_window(window_id, |cx| {
5569                let view_2 = cx.add_view(|_| View {
5570                    events: view_events.clone(),
5571                    name: "view 2".to_string(),
5572                    child: None,
5573                });
5574                view_1.update(cx, |view_1, cx| {
5575                    view_1.child = Some(view_2.clone().into_any());
5576                    cx.notify();
5577                });
5578                view_2
5579            })
5580            .unwrap();
5581
5582        let observed_events: Arc<Mutex<Vec<String>>> = Default::default();
5583        view_1.update(cx, |_, cx| {
5584            cx.observe_focus(&view_2, {
5585                let observed_events = observed_events.clone();
5586                move |this, view, focused, cx| {
5587                    let label = if focused { "focus" } else { "blur" };
5588                    observed_events.lock().push(format!(
5589                        "{} observed {}'s {}",
5590                        this.name,
5591                        view.read(cx).name,
5592                        label
5593                    ))
5594                }
5595            })
5596            .detach();
5597        });
5598        view_2.update(cx, |_, cx| {
5599            cx.observe_focus(&view_1, {
5600                let observed_events = observed_events.clone();
5601                move |this, view, focused, cx| {
5602                    let label = if focused { "focus" } else { "blur" };
5603                    observed_events.lock().push(format!(
5604                        "{} observed {}'s {}",
5605                        this.name,
5606                        view.read(cx).name,
5607                        label
5608                    ))
5609                }
5610            })
5611            .detach();
5612        });
5613        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5614        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5615
5616        view_1.update(cx, |_, cx| {
5617            // Ensure only the last focus event is honored.
5618            cx.focus(&view_2);
5619            cx.focus(&view_1);
5620            cx.focus(&view_2);
5621        });
5622
5623        assert_eq!(
5624            mem::take(&mut *view_events.lock()),
5625            ["view 1 blurred", "view 2 focused"],
5626        );
5627        assert_eq!(
5628            mem::take(&mut *observed_events.lock()),
5629            [
5630                "view 2 observed view 1's blur",
5631                "view 1 observed view 2's focus"
5632            ]
5633        );
5634
5635        view_1.update(cx, |_, cx| cx.focus(&view_1));
5636        assert_eq!(
5637            mem::take(&mut *view_events.lock()),
5638            ["view 2 blurred", "view 1 focused"],
5639        );
5640        assert_eq!(
5641            mem::take(&mut *observed_events.lock()),
5642            [
5643                "view 1 observed view 2's blur",
5644                "view 2 observed view 1's focus"
5645            ]
5646        );
5647
5648        view_1.update(cx, |_, cx| cx.focus(&view_2));
5649        assert_eq!(
5650            mem::take(&mut *view_events.lock()),
5651            ["view 1 blurred", "view 2 focused"],
5652        );
5653        assert_eq!(
5654            mem::take(&mut *observed_events.lock()),
5655            [
5656                "view 2 observed view 1's blur",
5657                "view 1 observed view 2's focus"
5658            ]
5659        );
5660
5661        println!("=====================");
5662        view_1.update(cx, |view, _| {
5663            drop(view_2);
5664            view.child = None;
5665        });
5666        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5667        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5668    }
5669
5670    #[crate::test(self)]
5671    fn test_deserialize_actions(cx: &mut AppContext) {
5672        #[derive(Clone, Debug, Deserialize, PartialEq, Eq)]
5673        pub struct ComplexAction {
5674            arg: String,
5675            count: usize,
5676        }
5677
5678        actions!(test::something, [SimpleAction]);
5679        impl_actions!(test::something, [ComplexAction]);
5680
5681        cx.add_global_action(move |_: &SimpleAction, _: &mut AppContext| {});
5682        cx.add_global_action(move |_: &ComplexAction, _: &mut AppContext| {});
5683
5684        let action1 = cx
5685            .deserialize_action(
5686                "test::something::ComplexAction",
5687                Some(serde_json::from_str(r#"{"arg": "a", "count": 5}"#).unwrap()),
5688            )
5689            .unwrap();
5690        let action2 = cx
5691            .deserialize_action("test::something::SimpleAction", None)
5692            .unwrap();
5693        assert_eq!(
5694            action1.as_any().downcast_ref::<ComplexAction>().unwrap(),
5695            &ComplexAction {
5696                arg: "a".to_string(),
5697                count: 5,
5698            }
5699        );
5700        assert_eq!(
5701            action2.as_any().downcast_ref::<SimpleAction>().unwrap(),
5702            &SimpleAction
5703        );
5704    }
5705
5706    #[crate::test(self)]
5707    fn test_dispatch_action(cx: &mut AppContext) {
5708        struct ViewA {
5709            id: usize,
5710            child: Option<AnyViewHandle>,
5711        }
5712
5713        impl Entity for ViewA {
5714            type Event = ();
5715        }
5716
5717        impl View for ViewA {
5718            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5719                self.child
5720                    .as_ref()
5721                    .map(|child| ChildView::new(child, cx).into_any())
5722                    .unwrap_or(Empty::new().into_any())
5723            }
5724
5725            fn ui_name() -> &'static str {
5726                "View"
5727            }
5728        }
5729
5730        struct ViewB {
5731            id: usize,
5732            child: Option<AnyViewHandle>,
5733        }
5734
5735        impl Entity for ViewB {
5736            type Event = ();
5737        }
5738
5739        impl View for ViewB {
5740            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5741                self.child
5742                    .as_ref()
5743                    .map(|child| ChildView::new(child, cx).into_any())
5744                    .unwrap_or(Empty::new().into_any())
5745            }
5746
5747            fn ui_name() -> &'static str {
5748                "View"
5749            }
5750        }
5751
5752        #[derive(Clone, Default, Deserialize, PartialEq)]
5753        pub struct Action(pub String);
5754
5755        impl_actions!(test, [Action]);
5756
5757        let actions = Rc::new(RefCell::new(Vec::new()));
5758
5759        cx.add_global_action({
5760            let actions = actions.clone();
5761            move |_: &Action, _: &mut AppContext| {
5762                actions.borrow_mut().push("global".to_string());
5763            }
5764        });
5765
5766        cx.add_action({
5767            let actions = actions.clone();
5768            move |view: &mut ViewA, action: &Action, cx| {
5769                assert_eq!(action.0, "bar");
5770                cx.propagate_action();
5771                actions.borrow_mut().push(format!("{} a", view.id));
5772            }
5773        });
5774
5775        cx.add_action({
5776            let actions = actions.clone();
5777            move |view: &mut ViewA, _: &Action, cx| {
5778                if view.id != 1 {
5779                    cx.add_view(|cx| {
5780                        cx.propagate_action(); // Still works on a nested ViewContext
5781                        ViewB { id: 5, child: None }
5782                    });
5783                }
5784                actions.borrow_mut().push(format!("{} b", view.id));
5785            }
5786        });
5787
5788        cx.add_action({
5789            let actions = actions.clone();
5790            move |view: &mut ViewB, _: &Action, cx| {
5791                cx.propagate_action();
5792                actions.borrow_mut().push(format!("{} c", view.id));
5793            }
5794        });
5795
5796        cx.add_action({
5797            let actions = actions.clone();
5798            move |view: &mut ViewB, _: &Action, cx| {
5799                cx.propagate_action();
5800                actions.borrow_mut().push(format!("{} d", view.id));
5801            }
5802        });
5803
5804        cx.capture_action({
5805            let actions = actions.clone();
5806            move |view: &mut ViewA, _: &Action, cx| {
5807                cx.propagate_action();
5808                actions.borrow_mut().push(format!("{} capture", view.id));
5809            }
5810        });
5811
5812        let observed_actions = Rc::new(RefCell::new(Vec::new()));
5813        cx.observe_actions({
5814            let observed_actions = observed_actions.clone();
5815            move |action_id, _| observed_actions.borrow_mut().push(action_id)
5816        })
5817        .detach();
5818
5819        let (window_id, view_1) =
5820            cx.add_window(Default::default(), |_| ViewA { id: 1, child: None });
5821        let view_2 = cx
5822            .update_window(window_id, |cx| {
5823                let child = cx.add_view(|_| ViewB { id: 2, child: None });
5824                view_1.update(cx, |view, cx| {
5825                    view.child = Some(child.clone().into_any());
5826                    cx.notify();
5827                });
5828                child
5829            })
5830            .unwrap();
5831        let view_3 = cx
5832            .update_window(window_id, |cx| {
5833                let child = cx.add_view(|_| ViewA { id: 3, child: None });
5834                view_2.update(cx, |view, cx| {
5835                    view.child = Some(child.clone().into_any());
5836                    cx.notify();
5837                });
5838                child
5839            })
5840            .unwrap();
5841        let view_4 = cx
5842            .update_window(window_id, |cx| {
5843                let child = cx.add_view(|_| ViewB { id: 4, child: None });
5844                view_3.update(cx, |view, cx| {
5845                    view.child = Some(child.clone().into_any());
5846                    cx.notify();
5847                });
5848                child
5849            })
5850            .unwrap();
5851
5852        cx.update_window(window_id, |cx| {
5853            cx.dispatch_action(Some(view_4.id()), &Action("bar".to_string()))
5854        });
5855
5856        assert_eq!(
5857            *actions.borrow(),
5858            vec![
5859                "1 capture",
5860                "3 capture",
5861                "4 d",
5862                "4 c",
5863                "3 b",
5864                "3 a",
5865                "2 d",
5866                "2 c",
5867                "1 b"
5868            ]
5869        );
5870        assert_eq!(*observed_actions.borrow(), [Action::default().id()]);
5871
5872        // Remove view_1, which doesn't propagate the action
5873
5874        let (window_id, view_2) =
5875            cx.add_window(Default::default(), |_| ViewB { id: 2, child: None });
5876        let view_3 = cx
5877            .update_window(window_id, |cx| {
5878                let child = cx.add_view(|_| ViewA { id: 3, child: None });
5879                view_2.update(cx, |view, cx| {
5880                    view.child = Some(child.clone().into_any());
5881                    cx.notify();
5882                });
5883                child
5884            })
5885            .unwrap();
5886        let view_4 = cx
5887            .update_window(window_id, |cx| {
5888                let child = cx.add_view(|_| ViewB { id: 4, child: None });
5889                view_3.update(cx, |view, cx| {
5890                    view.child = Some(child.clone().into_any());
5891                    cx.notify();
5892                });
5893                child
5894            })
5895            .unwrap();
5896
5897        actions.borrow_mut().clear();
5898        cx.update_window(window_id, |cx| {
5899            cx.dispatch_action(Some(view_4.id()), &Action("bar".to_string()))
5900        });
5901
5902        assert_eq!(
5903            *actions.borrow(),
5904            vec![
5905                "3 capture",
5906                "4 d",
5907                "4 c",
5908                "3 b",
5909                "3 a",
5910                "2 d",
5911                "2 c",
5912                "global"
5913            ]
5914        );
5915        assert_eq!(
5916            *observed_actions.borrow(),
5917            [Action::default().id(), Action::default().id()]
5918        );
5919    }
5920
5921    #[crate::test(self)]
5922    fn test_dispatch_keystroke(cx: &mut AppContext) {
5923        #[derive(Clone, Deserialize, PartialEq)]
5924        pub struct Action(String);
5925
5926        impl_actions!(test, [Action]);
5927
5928        struct View {
5929            id: usize,
5930            keymap_context: KeymapContext,
5931            child: Option<AnyViewHandle>,
5932        }
5933
5934        impl Entity for View {
5935            type Event = ();
5936        }
5937
5938        impl super::View for View {
5939            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
5940                self.child
5941                    .as_ref()
5942                    .map(|child| ChildView::new(child, cx).into_any())
5943                    .unwrap_or(Empty::new().into_any())
5944            }
5945
5946            fn ui_name() -> &'static str {
5947                "View"
5948            }
5949
5950            fn update_keymap_context(&self, keymap: &mut KeymapContext, _: &AppContext) {
5951                *keymap = self.keymap_context.clone();
5952            }
5953        }
5954
5955        impl View {
5956            fn new(id: usize) -> Self {
5957                View {
5958                    id,
5959                    keymap_context: KeymapContext::default(),
5960                    child: None,
5961                }
5962            }
5963        }
5964
5965        let mut view_1 = View::new(1);
5966        let mut view_2 = View::new(2);
5967        let mut view_3 = View::new(3);
5968        view_1.keymap_context.add_identifier("a");
5969        view_2.keymap_context.add_identifier("a");
5970        view_2.keymap_context.add_identifier("b");
5971        view_3.keymap_context.add_identifier("a");
5972        view_3.keymap_context.add_identifier("b");
5973        view_3.keymap_context.add_identifier("c");
5974
5975        let (window_id, _view_1) = cx.add_window(Default::default(), |cx| {
5976            let view_2 = cx.add_view(|cx| {
5977                let view_3 = cx.add_view(|cx| {
5978                    cx.focus_self();
5979                    view_3
5980                });
5981                view_2.child = Some(view_3.into_any());
5982                view_2
5983            });
5984            view_1.child = Some(view_2.into_any());
5985            view_1
5986        });
5987
5988        // This binding only dispatches an action on view 2 because that view will have
5989        // "a" and "b" in its context, but not "c".
5990        cx.add_bindings(vec![Binding::new(
5991            "a",
5992            Action("a".to_string()),
5993            Some("a && b && !c"),
5994        )]);
5995
5996        cx.add_bindings(vec![Binding::new("b", Action("b".to_string()), None)]);
5997
5998        // This binding only dispatches an action on views 2 and 3, because they have
5999        // a parent view with a in its context
6000        cx.add_bindings(vec![Binding::new(
6001            "c",
6002            Action("c".to_string()),
6003            Some("b > c"),
6004        )]);
6005
6006        // This binding only dispatches an action on view 2, because they have
6007        // a parent view with a in its context
6008        cx.add_bindings(vec![Binding::new(
6009            "d",
6010            Action("d".to_string()),
6011            Some("a && !b > b"),
6012        )]);
6013
6014        let actions = Rc::new(RefCell::new(Vec::new()));
6015        cx.add_action({
6016            let actions = actions.clone();
6017            move |view: &mut View, action: &Action, cx| {
6018                actions
6019                    .borrow_mut()
6020                    .push(format!("{} {}", view.id, action.0));
6021
6022                if action.0 == "b" {
6023                    cx.propagate_action();
6024                }
6025            }
6026        });
6027
6028        cx.add_global_action({
6029            let actions = actions.clone();
6030            move |action: &Action, _| {
6031                actions.borrow_mut().push(format!("global {}", action.0));
6032            }
6033        });
6034
6035        cx.update_window(window_id, |cx| {
6036            cx.dispatch_keystroke(&Keystroke::parse("a").unwrap())
6037        });
6038        assert_eq!(&*actions.borrow(), &["2 a"]);
6039        actions.borrow_mut().clear();
6040
6041        cx.update_window(window_id, |cx| {
6042            cx.dispatch_keystroke(&Keystroke::parse("b").unwrap());
6043        });
6044
6045        assert_eq!(&*actions.borrow(), &["3 b", "2 b", "1 b", "global b"]);
6046        actions.borrow_mut().clear();
6047
6048        cx.update_window(window_id, |cx| {
6049            cx.dispatch_keystroke(&Keystroke::parse("c").unwrap());
6050        });
6051        assert_eq!(&*actions.borrow(), &["3 c"]);
6052        actions.borrow_mut().clear();
6053
6054        cx.update_window(window_id, |cx| {
6055            cx.dispatch_keystroke(&Keystroke::parse("d").unwrap());
6056        });
6057        assert_eq!(&*actions.borrow(), &["2 d"]);
6058        actions.borrow_mut().clear();
6059    }
6060
6061    #[crate::test(self)]
6062    fn test_keystrokes_for_action(cx: &mut TestAppContext) {
6063        actions!(test, [Action1, Action2, GlobalAction]);
6064
6065        struct View1 {
6066            child: ViewHandle<View2>,
6067        }
6068        struct View2 {}
6069
6070        impl Entity for View1 {
6071            type Event = ();
6072        }
6073        impl Entity for View2 {
6074            type Event = ();
6075        }
6076
6077        impl super::View for View1 {
6078            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
6079                ChildView::new(&self.child, cx).into_any()
6080            }
6081            fn ui_name() -> &'static str {
6082                "View1"
6083            }
6084        }
6085        impl super::View for View2 {
6086            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6087                Empty::new().into_any()
6088            }
6089            fn ui_name() -> &'static str {
6090                "View2"
6091            }
6092        }
6093
6094        let (window_id, view_1) = cx.add_window(|cx| {
6095            let view_2 = cx.add_view(|cx| {
6096                cx.focus_self();
6097                View2 {}
6098            });
6099            View1 { child: view_2 }
6100        });
6101        let view_2 = view_1.read_with(cx, |view, _| view.child.clone());
6102
6103        cx.update(|cx| {
6104            cx.add_action(|_: &mut View1, _: &Action1, _cx| {});
6105            cx.add_action(|_: &mut View2, _: &Action2, _cx| {});
6106            cx.add_global_action(|_: &GlobalAction, _| {});
6107            cx.add_bindings(vec![
6108                Binding::new("a", Action1, Some("View1")),
6109                Binding::new("b", Action2, Some("View1 > View2")),
6110                Binding::new("c", GlobalAction, Some("View3")), // View 3 does not exist
6111            ]);
6112        });
6113
6114        let view_1_id = view_1.id();
6115        view_1.update(cx, |_, cx| {
6116            view_2.update(cx, |_, cx| {
6117                // Sanity check
6118                let mut new_parents = Default::default();
6119                let mut notify_views_if_parents_change = Default::default();
6120                let mut layout_cx = LayoutContext::new(
6121                    cx,
6122                    &mut new_parents,
6123                    &mut notify_views_if_parents_change,
6124                    false,
6125                );
6126                assert_eq!(
6127                    layout_cx
6128                        .keystrokes_for_action(view_1_id, &Action1)
6129                        .unwrap()
6130                        .as_slice(),
6131                    &[Keystroke::parse("a").unwrap()]
6132                );
6133                assert_eq!(
6134                    layout_cx
6135                        .keystrokes_for_action(view_2.id(), &Action2)
6136                        .unwrap()
6137                        .as_slice(),
6138                    &[Keystroke::parse("b").unwrap()]
6139                );
6140
6141                // The 'a' keystroke propagates up the view tree from view_2
6142                // to view_1. The action, Action1, is handled by view_1.
6143                assert_eq!(
6144                    layout_cx
6145                        .keystrokes_for_action(view_2.id(), &Action1)
6146                        .unwrap()
6147                        .as_slice(),
6148                    &[Keystroke::parse("a").unwrap()]
6149                );
6150
6151                // Actions that are handled below the current view don't have bindings
6152                assert_eq!(layout_cx.keystrokes_for_action(view_1_id, &Action2), None);
6153
6154                // Actions that are handled in other branches of the tree should not have a binding
6155                assert_eq!(
6156                    layout_cx.keystrokes_for_action(view_2.id(), &GlobalAction),
6157                    None
6158                );
6159            });
6160        });
6161
6162        // Check that global actions do not have a binding, even if a binding does exist in another view
6163        assert_eq!(
6164            &available_actions(window_id, view_1.id(), cx),
6165            &[
6166                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
6167                ("test::GlobalAction", vec![])
6168            ],
6169        );
6170
6171        // Check that view 1 actions and bindings are available even when called from view 2
6172        assert_eq!(
6173            &available_actions(window_id, view_2.id(), cx),
6174            &[
6175                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
6176                ("test::Action2", vec![Keystroke::parse("b").unwrap()]),
6177                ("test::GlobalAction", vec![]),
6178            ],
6179        );
6180
6181        // Produces a list of actions and key bindings
6182        fn available_actions(
6183            window_id: usize,
6184            view_id: usize,
6185            cx: &TestAppContext,
6186        ) -> Vec<(&'static str, Vec<Keystroke>)> {
6187            cx.available_actions(window_id, view_id)
6188                .into_iter()
6189                .map(|(action_name, _, bindings)| {
6190                    (
6191                        action_name,
6192                        bindings
6193                            .iter()
6194                            .map(|binding| binding.keystrokes()[0].clone())
6195                            .collect::<Vec<_>>(),
6196                    )
6197                })
6198                .sorted_by(|(name1, _), (name2, _)| name1.cmp(name2))
6199                .collect()
6200        }
6201    }
6202
6203    #[crate::test(self)]
6204    fn test_keystrokes_for_action_with_data(cx: &mut TestAppContext) {
6205        #[derive(Clone, Debug, Deserialize, PartialEq)]
6206        struct ActionWithArg {
6207            #[serde(default)]
6208            arg: bool,
6209        }
6210
6211        struct View;
6212        impl super::Entity for View {
6213            type Event = ();
6214        }
6215        impl super::View for View {
6216            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6217                Empty::new().into_any()
6218            }
6219            fn ui_name() -> &'static str {
6220                "View"
6221            }
6222        }
6223
6224        impl_actions!(test, [ActionWithArg]);
6225
6226        let (window_id, view) = cx.add_window(|_| View);
6227        cx.update(|cx| {
6228            cx.add_global_action(|_: &ActionWithArg, _| {});
6229            cx.add_bindings(vec![
6230                Binding::new("a", ActionWithArg { arg: false }, None),
6231                Binding::new("shift-a", ActionWithArg { arg: true }, None),
6232            ]);
6233        });
6234
6235        let actions = cx.available_actions(window_id, view.id());
6236        assert_eq!(
6237            actions[0].1.as_any().downcast_ref::<ActionWithArg>(),
6238            Some(&ActionWithArg { arg: false })
6239        );
6240        assert_eq!(
6241            actions[0]
6242                .2
6243                .iter()
6244                .map(|b| b.keystrokes()[0].clone())
6245                .collect::<Vec<_>>(),
6246            vec![Keystroke::parse("a").unwrap()],
6247        );
6248    }
6249
6250    #[crate::test(self)]
6251    async fn test_model_condition(cx: &mut TestAppContext) {
6252        struct Counter(usize);
6253
6254        impl super::Entity for Counter {
6255            type Event = ();
6256        }
6257
6258        impl Counter {
6259            fn inc(&mut self, cx: &mut ModelContext<Self>) {
6260                self.0 += 1;
6261                cx.notify();
6262            }
6263        }
6264
6265        let model = cx.add_model(|_| Counter(0));
6266
6267        let condition1 = model.condition(cx, |model, _| model.0 == 2);
6268        let condition2 = model.condition(cx, |model, _| model.0 == 3);
6269        smol::pin!(condition1, condition2);
6270
6271        model.update(cx, |model, cx| model.inc(cx));
6272        assert_eq!(poll_once(&mut condition1).await, None);
6273        assert_eq!(poll_once(&mut condition2).await, None);
6274
6275        model.update(cx, |model, cx| model.inc(cx));
6276        assert_eq!(poll_once(&mut condition1).await, Some(()));
6277        assert_eq!(poll_once(&mut condition2).await, None);
6278
6279        model.update(cx, |model, cx| model.inc(cx));
6280        assert_eq!(poll_once(&mut condition2).await, Some(()));
6281
6282        model.update(cx, |_, cx| cx.notify());
6283    }
6284
6285    #[crate::test(self)]
6286    #[should_panic]
6287    async fn test_model_condition_timeout(cx: &mut TestAppContext) {
6288        struct Model;
6289
6290        impl super::Entity for Model {
6291            type Event = ();
6292        }
6293
6294        let model = cx.add_model(|_| Model);
6295        model.condition(cx, |_, _| false).await;
6296    }
6297
6298    #[crate::test(self)]
6299    #[should_panic(expected = "model dropped with pending condition")]
6300    async fn test_model_condition_panic_on_drop(cx: &mut TestAppContext) {
6301        struct Model;
6302
6303        impl super::Entity for Model {
6304            type Event = ();
6305        }
6306
6307        let model = cx.add_model(|_| Model);
6308        let condition = model.condition(cx, |_, _| false);
6309        cx.update(|_| drop(model));
6310        condition.await;
6311    }
6312
6313    #[crate::test(self)]
6314    async fn test_view_condition(cx: &mut TestAppContext) {
6315        struct Counter(usize);
6316
6317        impl super::Entity for Counter {
6318            type Event = ();
6319        }
6320
6321        impl super::View for Counter {
6322            fn ui_name() -> &'static str {
6323                "test view"
6324            }
6325
6326            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6327                Empty::new().into_any()
6328            }
6329        }
6330
6331        impl Counter {
6332            fn inc(&mut self, cx: &mut ViewContext<Self>) {
6333                self.0 += 1;
6334                cx.notify();
6335            }
6336        }
6337
6338        let (_, view) = cx.add_window(|_| Counter(0));
6339
6340        let condition1 = view.condition(cx, |view, _| view.0 == 2);
6341        let condition2 = view.condition(cx, |view, _| view.0 == 3);
6342        smol::pin!(condition1, condition2);
6343
6344        view.update(cx, |view, cx| view.inc(cx));
6345        assert_eq!(poll_once(&mut condition1).await, None);
6346        assert_eq!(poll_once(&mut condition2).await, None);
6347
6348        view.update(cx, |view, cx| view.inc(cx));
6349        assert_eq!(poll_once(&mut condition1).await, Some(()));
6350        assert_eq!(poll_once(&mut condition2).await, None);
6351
6352        view.update(cx, |view, cx| view.inc(cx));
6353        assert_eq!(poll_once(&mut condition2).await, Some(()));
6354        view.update(cx, |_, cx| cx.notify());
6355    }
6356
6357    #[crate::test(self)]
6358    #[should_panic]
6359    async fn test_view_condition_timeout(cx: &mut TestAppContext) {
6360        let (_, view) = cx.add_window(|_| TestView::default());
6361        view.condition(cx, |_, _| false).await;
6362    }
6363
6364    #[crate::test(self)]
6365    #[should_panic(expected = "view dropped with pending condition")]
6366    async fn test_view_condition_panic_on_drop(cx: &mut TestAppContext) {
6367        let (window_id, _root_view) = cx.add_window(|_| TestView::default());
6368        let view = cx.add_view(window_id, |_| TestView::default());
6369
6370        let condition = view.condition(cx, |_, _| false);
6371        cx.update(|_| drop(view));
6372        condition.await;
6373    }
6374
6375    #[crate::test(self)]
6376    fn test_refresh_windows(cx: &mut AppContext) {
6377        struct View(usize);
6378
6379        impl super::Entity for View {
6380            type Event = ();
6381        }
6382
6383        impl super::View for View {
6384            fn ui_name() -> &'static str {
6385                "test view"
6386            }
6387
6388            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6389                Empty::new().into_any_named(format!("render count: {}", post_inc(&mut self.0)))
6390            }
6391        }
6392
6393        let (window_id, root_view) = cx.add_window(Default::default(), |_| View(0));
6394        cx.update_window(window_id, |cx| {
6395            assert_eq!(
6396                cx.window.rendered_views[&root_view.id()].name(),
6397                Some("render count: 0")
6398            );
6399        });
6400
6401        let view = cx
6402            .update_window(window_id, |cx| {
6403                cx.refresh_windows();
6404                cx.add_view(|_| View(0))
6405            })
6406            .unwrap();
6407
6408        cx.update_window(window_id, |cx| {
6409            assert_eq!(
6410                cx.window.rendered_views[&root_view.id()].name(),
6411                Some("render count: 1")
6412            );
6413            assert_eq!(
6414                cx.window.rendered_views[&view.id()].name(),
6415                Some("render count: 0")
6416            );
6417        });
6418
6419        cx.update(|cx| cx.refresh_windows());
6420
6421        cx.update_window(window_id, |cx| {
6422            assert_eq!(
6423                cx.window.rendered_views[&root_view.id()].name(),
6424                Some("render count: 2")
6425            );
6426            assert_eq!(
6427                cx.window.rendered_views[&view.id()].name(),
6428                Some("render count: 1")
6429            );
6430        });
6431
6432        cx.update(|cx| {
6433            cx.refresh_windows();
6434            drop(view);
6435        });
6436
6437        cx.update_window(window_id, |cx| {
6438            assert_eq!(
6439                cx.window.rendered_views[&root_view.id()].name(),
6440                Some("render count: 3")
6441            );
6442            assert_eq!(cx.window.rendered_views.len(), 1);
6443        });
6444    }
6445
6446    #[crate::test(self)]
6447    async fn test_labeled_tasks(cx: &mut TestAppContext) {
6448        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6449        let (mut sender, mut receiver) = postage::oneshot::channel::<()>();
6450        let task = cx
6451            .update(|cx| cx.spawn_labeled("Test Label", |_| async move { receiver.recv().await }));
6452
6453        assert_eq!(
6454            Some("Test Label"),
6455            cx.update(|cx| cx.active_labeled_tasks().next())
6456        );
6457        sender
6458            .send(())
6459            .await
6460            .expect("Could not send message to complete task");
6461        task.await;
6462
6463        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6464    }
6465
6466    #[crate::test(self)]
6467    async fn test_window_activation(cx: &mut TestAppContext) {
6468        struct View(&'static str);
6469
6470        impl super::Entity for View {
6471            type Event = ();
6472        }
6473
6474        impl super::View for View {
6475            fn ui_name() -> &'static str {
6476                "test view"
6477            }
6478
6479            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6480                Empty::new().into_any()
6481            }
6482        }
6483
6484        let events = Rc::new(RefCell::new(Vec::new()));
6485        let (window_1, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6486            cx.observe_window_activation({
6487                let events = events.clone();
6488                move |this, active, _| events.borrow_mut().push((this.0, active))
6489            })
6490            .detach();
6491            View("window 1")
6492        });
6493        assert_eq!(mem::take(&mut *events.borrow_mut()), [("window 1", true)]);
6494
6495        let (window_2, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6496            cx.observe_window_activation({
6497                let events = events.clone();
6498                move |this, active, _| events.borrow_mut().push((this.0, active))
6499            })
6500            .detach();
6501            View("window 2")
6502        });
6503        assert_eq!(
6504            mem::take(&mut *events.borrow_mut()),
6505            [("window 1", false), ("window 2", true)]
6506        );
6507
6508        let (window_3, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6509            cx.observe_window_activation({
6510                let events = events.clone();
6511                move |this, active, _| events.borrow_mut().push((this.0, active))
6512            })
6513            .detach();
6514            View("window 3")
6515        });
6516        assert_eq!(
6517            mem::take(&mut *events.borrow_mut()),
6518            [("window 2", false), ("window 3", true)]
6519        );
6520
6521        cx.simulate_window_activation(Some(window_2));
6522        assert_eq!(
6523            mem::take(&mut *events.borrow_mut()),
6524            [("window 3", false), ("window 2", true)]
6525        );
6526
6527        cx.simulate_window_activation(Some(window_1));
6528        assert_eq!(
6529            mem::take(&mut *events.borrow_mut()),
6530            [("window 2", false), ("window 1", true)]
6531        );
6532
6533        cx.simulate_window_activation(Some(window_3));
6534        assert_eq!(
6535            mem::take(&mut *events.borrow_mut()),
6536            [("window 1", false), ("window 3", true)]
6537        );
6538
6539        cx.simulate_window_activation(Some(window_3));
6540        assert_eq!(mem::take(&mut *events.borrow_mut()), []);
6541    }
6542
6543    #[crate::test(self)]
6544    fn test_child_view(cx: &mut TestAppContext) {
6545        struct Child {
6546            rendered: Rc<Cell<bool>>,
6547            dropped: Rc<Cell<bool>>,
6548        }
6549
6550        impl super::Entity for Child {
6551            type Event = ();
6552        }
6553
6554        impl super::View for Child {
6555            fn ui_name() -> &'static str {
6556                "child view"
6557            }
6558
6559            fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6560                self.rendered.set(true);
6561                Empty::new().into_any()
6562            }
6563        }
6564
6565        impl Drop for Child {
6566            fn drop(&mut self) {
6567                self.dropped.set(true);
6568            }
6569        }
6570
6571        struct Parent {
6572            child: Option<ViewHandle<Child>>,
6573        }
6574
6575        impl super::Entity for Parent {
6576            type Event = ();
6577        }
6578
6579        impl super::View for Parent {
6580            fn ui_name() -> &'static str {
6581                "parent view"
6582            }
6583
6584            fn render(&mut self, cx: &mut ViewContext<Self>) -> AnyElement<Self> {
6585                if let Some(child) = self.child.as_ref() {
6586                    ChildView::new(child, cx).into_any()
6587                } else {
6588                    Empty::new().into_any()
6589                }
6590            }
6591        }
6592
6593        let child_rendered = Rc::new(Cell::new(false));
6594        let child_dropped = Rc::new(Cell::new(false));
6595        let (_, root_view) = cx.add_window(|cx| Parent {
6596            child: Some(cx.add_view(|_| Child {
6597                rendered: child_rendered.clone(),
6598                dropped: child_dropped.clone(),
6599            })),
6600        });
6601        assert!(child_rendered.take());
6602        assert!(!child_dropped.take());
6603
6604        root_view.update(cx, |view, cx| {
6605            view.child.take();
6606            cx.notify();
6607        });
6608        assert!(!child_rendered.take());
6609        assert!(child_dropped.take());
6610    }
6611
6612    #[derive(Default)]
6613    struct TestView {
6614        events: Vec<String>,
6615    }
6616
6617    impl Entity for TestView {
6618        type Event = String;
6619    }
6620
6621    impl View for TestView {
6622        fn ui_name() -> &'static str {
6623            "TestView"
6624        }
6625
6626        fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
6627            Empty::new().into_any()
6628        }
6629    }
6630}