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 uuid::Uuid;
  31
  32pub use action::*;
  33use callback_collection::CallbackCollection;
  34use collections::{hash_map::Entry, BTreeMap, HashMap, HashSet, VecDeque};
  35pub use menu::*;
  36use platform::Event;
  37#[cfg(any(test, feature = "test-support"))]
  38use ref_counts::LeakDetector;
  39#[cfg(any(test, feature = "test-support"))]
  40pub use test_app_context::{ContextHandle, TestAppContext};
  41use window_input_handler::WindowInputHandler;
  42
  43use crate::{
  44    elements::{AnyRootElement, Element, RootElement},
  45    executor::{self, Task},
  46    keymap_matcher::{self, Binding, KeymapContext, KeymapMatcher, Keystroke, MatchResult},
  47    platform::{
  48        self, FontSystem, KeyDownEvent, KeyUpEvent, ModifiersChangedEvent, MouseButton,
  49        PathPromptOptions, Platform, PromptLevel, WindowBounds, WindowOptions,
  50    },
  51    util::post_inc,
  52    window::{Window, WindowContext},
  53    AssetCache, AssetSource, ClipboardItem, FontCache, MouseRegionId,
  54};
  55
  56use self::ref_counts::RefCounts;
  57
  58pub trait Entity: 'static {
  59    type Event;
  60
  61    fn release(&mut self, _: &mut AppContext) {}
  62    fn app_will_quit(
  63        &mut self,
  64        _: &mut AppContext,
  65    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
  66        None
  67    }
  68}
  69
  70pub trait View: Entity + Sized {
  71    fn ui_name() -> &'static str;
  72    fn render(&mut self, cx: &mut ViewContext<'_, '_, '_, Self>) -> Element<Self>;
  73    fn focus_in(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  74    fn focus_out(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {}
  75    fn key_down(&mut self, _: &KeyDownEvent, _: &mut ViewContext<Self>) -> bool {
  76        false
  77    }
  78    fn key_up(&mut self, _: &KeyUpEvent, _: &mut ViewContext<Self>) -> bool {
  79        false
  80    }
  81    fn modifiers_changed(&mut self, _: &ModifiersChangedEvent, _: &mut ViewContext<Self>) -> bool {
  82        false
  83    }
  84
  85    fn keymap_context(&self, _: &AppContext) -> keymap_matcher::KeymapContext {
  86        Self::default_keymap_context()
  87    }
  88    fn default_keymap_context() -> keymap_matcher::KeymapContext {
  89        let mut cx = keymap_matcher::KeymapContext::default();
  90        cx.add_identifier(Self::ui_name());
  91        cx
  92    }
  93    fn debug_json(&self, _: &AppContext) -> serde_json::Value {
  94        serde_json::Value::Null
  95    }
  96
  97    fn text_for_range(&self, _: Range<usize>, _: &AppContext) -> Option<String> {
  98        None
  99    }
 100    fn selected_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 101        None
 102    }
 103    fn marked_text_range(&self, _: &AppContext) -> Option<Range<usize>> {
 104        None
 105    }
 106    fn unmark_text(&mut self, _: &mut ViewContext<Self>) {}
 107    fn replace_text_in_range(
 108        &mut self,
 109        _: Option<Range<usize>>,
 110        _: &str,
 111        _: &mut ViewContext<Self>,
 112    ) {
 113    }
 114    fn replace_and_mark_text_in_range(
 115        &mut self,
 116        _: Option<Range<usize>>,
 117        _: &str,
 118        _: Option<Range<usize>>,
 119        _: &mut ViewContext<Self>,
 120    ) {
 121    }
 122}
 123
 124pub trait ReadModel {
 125    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T;
 126}
 127
 128pub trait ReadModelWith {
 129    fn read_model_with<E: Entity, T>(
 130        &self,
 131        handle: &ModelHandle<E>,
 132        read: &mut dyn FnMut(&E, &AppContext) -> T,
 133    ) -> T;
 134}
 135
 136pub trait UpdateModel {
 137    fn update_model<T: Entity, O>(
 138        &mut self,
 139        handle: &ModelHandle<T>,
 140        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
 141    ) -> O;
 142}
 143
 144pub trait UpgradeModelHandle {
 145    fn upgrade_model_handle<T: Entity>(
 146        &self,
 147        handle: &WeakModelHandle<T>,
 148    ) -> Option<ModelHandle<T>>;
 149
 150    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool;
 151
 152    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle>;
 153}
 154
 155pub trait UpgradeViewHandle {
 156    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>>;
 157
 158    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle>;
 159}
 160
 161pub trait ReadView {
 162    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T;
 163}
 164
 165pub trait ReadViewWith {
 166    fn read_view_with<V, T>(
 167        &self,
 168        handle: &ViewHandle<V>,
 169        read: &mut dyn FnMut(&V, &AppContext) -> T,
 170    ) -> T
 171    where
 172        V: View;
 173}
 174
 175pub trait UpdateView {
 176    fn update_view<T, S>(
 177        &mut self,
 178        handle: &ViewHandle<T>,
 179        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 180    ) -> S
 181    where
 182        T: View;
 183}
 184
 185#[derive(Clone)]
 186pub struct App(Rc<RefCell<AppContext>>);
 187
 188#[derive(Clone)]
 189pub struct AsyncAppContext(Rc<RefCell<AppContext>>);
 190
 191impl App {
 192    pub fn new(asset_source: impl AssetSource) -> Result<Self> {
 193        let platform = platform::current::platform();
 194        let foreground = Rc::new(executor::Foreground::platform(platform.dispatcher())?);
 195        let foreground_platform = platform::current::foreground_platform(foreground.clone());
 196        let app = Self(Rc::new(RefCell::new(AppContext::new(
 197            foreground,
 198            Arc::new(executor::Background::new()),
 199            platform.clone(),
 200            foreground_platform.clone(),
 201            Arc::new(FontCache::new(platform.fonts())),
 202            Default::default(),
 203            asset_source,
 204        ))));
 205
 206        foreground_platform.on_quit(Box::new({
 207            let cx = app.0.clone();
 208            move || {
 209                cx.borrow_mut().quit();
 210            }
 211        }));
 212        setup_menu_handlers(foreground_platform.as_ref(), &app);
 213
 214        app.0.borrow_mut().weak_self = Some(Rc::downgrade(&app.0));
 215        Ok(app)
 216    }
 217
 218    pub fn background(&self) -> Arc<executor::Background> {
 219        self.0.borrow().background().clone()
 220    }
 221
 222    pub fn on_become_active<F>(self, mut callback: F) -> Self
 223    where
 224        F: 'static + FnMut(&mut AppContext),
 225    {
 226        let cx = self.0.clone();
 227        self.0
 228            .borrow_mut()
 229            .foreground_platform
 230            .on_become_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 231        self
 232    }
 233
 234    pub fn on_resign_active<F>(self, mut callback: F) -> Self
 235    where
 236        F: 'static + FnMut(&mut AppContext),
 237    {
 238        let cx = self.0.clone();
 239        self.0
 240            .borrow_mut()
 241            .foreground_platform
 242            .on_resign_active(Box::new(move || callback(&mut *cx.borrow_mut())));
 243        self
 244    }
 245
 246    pub fn on_quit<F>(&mut self, mut callback: F) -> &mut Self
 247    where
 248        F: 'static + FnMut(&mut AppContext),
 249    {
 250        let cx = self.0.clone();
 251        self.0
 252            .borrow_mut()
 253            .foreground_platform
 254            .on_quit(Box::new(move || callback(&mut *cx.borrow_mut())));
 255        self
 256    }
 257
 258    /// Handle the application being re-activated when no windows are open.
 259    pub fn on_reopen<F>(&mut self, mut callback: F) -> &mut Self
 260    where
 261        F: 'static + FnMut(&mut AppContext),
 262    {
 263        let cx = self.0.clone();
 264        self.0
 265            .borrow_mut()
 266            .foreground_platform
 267            .on_reopen(Box::new(move || callback(&mut *cx.borrow_mut())));
 268        self
 269    }
 270
 271    pub fn on_event<F>(&mut self, mut callback: F) -> &mut Self
 272    where
 273        F: 'static + FnMut(Event, &mut AppContext) -> bool,
 274    {
 275        let cx = self.0.clone();
 276        self.0
 277            .borrow_mut()
 278            .foreground_platform
 279            .on_event(Box::new(move |event| {
 280                callback(event, &mut *cx.borrow_mut())
 281            }));
 282        self
 283    }
 284
 285    pub fn on_open_urls<F>(&mut self, mut callback: F) -> &mut Self
 286    where
 287        F: 'static + FnMut(Vec<String>, &mut AppContext),
 288    {
 289        let cx = self.0.clone();
 290        self.0
 291            .borrow_mut()
 292            .foreground_platform
 293            .on_open_urls(Box::new(move |urls| callback(urls, &mut *cx.borrow_mut())));
 294        self
 295    }
 296
 297    pub fn run<F>(self, on_finish_launching: F)
 298    where
 299        F: 'static + FnOnce(&mut AppContext),
 300    {
 301        let platform = self.0.borrow().foreground_platform.clone();
 302        platform.run(Box::new(move || {
 303            let mut cx = self.0.borrow_mut();
 304            let cx = &mut *cx;
 305            crate::views::init(cx);
 306            on_finish_launching(cx);
 307        }))
 308    }
 309
 310    pub fn platform(&self) -> Arc<dyn Platform> {
 311        self.0.borrow().platform.clone()
 312    }
 313
 314    pub fn font_cache(&self) -> Arc<FontCache> {
 315        self.0.borrow().font_cache.clone()
 316    }
 317
 318    fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 319        let mut state = self.0.borrow_mut();
 320        let result = state.update(callback);
 321        state.pending_notifications.clear();
 322        result
 323    }
 324
 325    fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 326        &mut self,
 327        window_id: usize,
 328        callback: F,
 329    ) -> Option<T> {
 330        let mut state = self.0.borrow_mut();
 331        let result = state.update_window(window_id, callback);
 332        state.pending_notifications.clear();
 333        result
 334    }
 335}
 336
 337impl AsyncAppContext {
 338    pub fn spawn<F, Fut, T>(&self, f: F) -> Task<T>
 339    where
 340        F: FnOnce(AsyncAppContext) -> Fut,
 341        Fut: 'static + Future<Output = T>,
 342        T: 'static,
 343    {
 344        self.0.borrow().foreground.spawn(f(self.clone()))
 345    }
 346
 347    pub fn read<T, F: FnOnce(&AppContext) -> T>(&self, callback: F) -> T {
 348        callback(&*self.0.borrow())
 349    }
 350
 351    pub fn update<T, F: FnOnce(&mut AppContext) -> T>(&mut self, callback: F) -> T {
 352        self.0.borrow_mut().update(callback)
 353    }
 354
 355    fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 356        &mut self,
 357        window_id: usize,
 358        callback: F,
 359    ) -> Option<T> {
 360        self.0.borrow_mut().update_window(window_id, callback)
 361    }
 362
 363    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
 364    where
 365        T: Entity,
 366        F: FnOnce(&mut ModelContext<T>) -> T,
 367    {
 368        self.update(|cx| cx.add_model(build_model))
 369    }
 370
 371    pub fn add_window<T, F>(
 372        &mut self,
 373        window_options: WindowOptions,
 374        build_root_view: F,
 375    ) -> (usize, ViewHandle<T>)
 376    where
 377        T: View,
 378        F: FnOnce(&mut ViewContext<T>) -> T,
 379    {
 380        self.update(|cx| cx.add_window(window_options, build_root_view))
 381    }
 382
 383    pub fn remove_window(&mut self, window_id: usize) {
 384        self.update(|cx| cx.remove_window(window_id))
 385    }
 386
 387    pub fn activate_window(&mut self, window_id: usize) {
 388        self.update_window(window_id, |cx| cx.activate_window());
 389    }
 390
 391    // TODO: Can we eliminate this method and move it to WindowContext then call it with update_window?s
 392    pub fn prompt(
 393        &mut self,
 394        window_id: usize,
 395        level: PromptLevel,
 396        msg: &str,
 397        answers: &[&str],
 398    ) -> Option<oneshot::Receiver<usize>> {
 399        self.update_window(window_id, |cx| cx.prompt(level, msg, answers))
 400    }
 401
 402    pub fn platform(&self) -> Arc<dyn Platform> {
 403        self.0.borrow().platform().clone()
 404    }
 405
 406    pub fn foreground(&self) -> Rc<executor::Foreground> {
 407        self.0.borrow().foreground.clone()
 408    }
 409
 410    pub fn background(&self) -> Arc<executor::Background> {
 411        self.0.borrow().background.clone()
 412    }
 413}
 414
 415impl UpdateModel for AsyncAppContext {
 416    fn update_model<E: Entity, O>(
 417        &mut self,
 418        handle: &ModelHandle<E>,
 419        update: &mut dyn FnMut(&mut E, &mut ModelContext<E>) -> O,
 420    ) -> O {
 421        self.0.borrow_mut().update_model(handle, update)
 422    }
 423}
 424
 425impl UpgradeModelHandle for AsyncAppContext {
 426    fn upgrade_model_handle<T: Entity>(
 427        &self,
 428        handle: &WeakModelHandle<T>,
 429    ) -> Option<ModelHandle<T>> {
 430        self.0.borrow().upgrade_model_handle(handle)
 431    }
 432
 433    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
 434        self.0.borrow().model_handle_is_upgradable(handle)
 435    }
 436
 437    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
 438        self.0.borrow().upgrade_any_model_handle(handle)
 439    }
 440}
 441
 442impl UpgradeViewHandle for AsyncAppContext {
 443    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
 444        self.0.borrow_mut().upgrade_view_handle(handle)
 445    }
 446
 447    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
 448        self.0.borrow_mut().upgrade_any_view_handle(handle)
 449    }
 450}
 451
 452impl ReadModelWith for AsyncAppContext {
 453    fn read_model_with<E: Entity, T>(
 454        &self,
 455        handle: &ModelHandle<E>,
 456        read: &mut dyn FnMut(&E, &AppContext) -> T,
 457    ) -> T {
 458        let cx = self.0.borrow();
 459        let cx = &*cx;
 460        read(handle.read(cx), cx)
 461    }
 462}
 463
 464impl UpdateView for AsyncAppContext {
 465    fn update_view<T, S>(
 466        &mut self,
 467        handle: &ViewHandle<T>,
 468        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
 469    ) -> S
 470    where
 471        T: View,
 472    {
 473        self.0.borrow_mut().update_view(handle, update)
 474    }
 475}
 476
 477impl ReadViewWith for AsyncAppContext {
 478    fn read_view_with<V, T>(
 479        &self,
 480        handle: &ViewHandle<V>,
 481        read: &mut dyn FnMut(&V, &AppContext) -> T,
 482    ) -> T
 483    where
 484        V: View,
 485    {
 486        let cx = self.0.borrow();
 487        let cx = &*cx;
 488        read(handle.read(cx), cx)
 489    }
 490}
 491
 492type ActionCallback = dyn FnMut(&mut dyn AnyView, &dyn Action, &mut WindowContext, usize);
 493type GlobalActionCallback = dyn FnMut(&dyn Action, &mut AppContext);
 494
 495type SubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool>;
 496type GlobalSubscriptionCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 497type ObservationCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 498type GlobalObservationCallback = Box<dyn FnMut(&mut AppContext)>;
 499type FocusObservationCallback = Box<dyn FnMut(bool, &mut AppContext) -> bool>;
 500type ReleaseObservationCallback = Box<dyn FnMut(&dyn Any, &mut AppContext)>;
 501type ActionObservationCallback = Box<dyn FnMut(TypeId, &mut AppContext)>;
 502type WindowActivationCallback = Box<dyn FnMut(bool, &mut AppContext) -> bool>;
 503type WindowFullscreenCallback = Box<dyn FnMut(bool, &mut AppContext) -> bool>;
 504type WindowBoundsCallback = Box<dyn FnMut(WindowBounds, Uuid, &mut AppContext) -> bool>;
 505type KeystrokeCallback =
 506    Box<dyn FnMut(&Keystroke, &MatchResult, Option<&Box<dyn Action>>, &mut AppContext) -> bool>;
 507type ActiveLabeledTasksCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 508type DeserializeActionCallback = fn(json: &str) -> anyhow::Result<Box<dyn Action>>;
 509type WindowShouldCloseSubscriptionCallback = Box<dyn FnMut(&mut AppContext) -> bool>;
 510
 511pub struct AppContext {
 512    models: HashMap<usize, Box<dyn AnyModel>>,
 513    views: HashMap<(usize, usize), Box<dyn AnyView>>,
 514    pub(crate) parents: HashMap<(usize, usize), ParentId>,
 515    windows: HashMap<usize, Window>,
 516    globals: HashMap<TypeId, Box<dyn Any>>,
 517    element_states: HashMap<ElementStateId, Box<dyn Any>>,
 518    background: Arc<executor::Background>,
 519    ref_counts: Arc<Mutex<RefCounts>>,
 520
 521    weak_self: Option<rc::Weak<RefCell<Self>>>,
 522    platform: Arc<dyn Platform>,
 523    foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 524    pub asset_cache: Arc<AssetCache>,
 525    font_system: Arc<dyn FontSystem>,
 526    pub font_cache: Arc<FontCache>,
 527    action_deserializers: HashMap<&'static str, (TypeId, DeserializeActionCallback)>,
 528    capture_actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 529    // Entity Types -> { Action Types -> Action Handlers }
 530    actions: HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>>,
 531    // Action Types -> Action Handlers
 532    global_actions: HashMap<TypeId, Box<GlobalActionCallback>>,
 533    keystroke_matcher: KeymapMatcher,
 534    next_entity_id: usize,
 535    next_window_id: usize,
 536    next_subscription_id: usize,
 537    frame_count: usize,
 538
 539    subscriptions: CallbackCollection<usize, SubscriptionCallback>,
 540    global_subscriptions: CallbackCollection<TypeId, GlobalSubscriptionCallback>,
 541    observations: CallbackCollection<usize, ObservationCallback>,
 542    global_observations: CallbackCollection<TypeId, GlobalObservationCallback>,
 543    focus_observations: CallbackCollection<usize, FocusObservationCallback>,
 544    release_observations: CallbackCollection<usize, ReleaseObservationCallback>,
 545    action_dispatch_observations: CallbackCollection<(), ActionObservationCallback>,
 546    window_activation_observations: CallbackCollection<usize, WindowActivationCallback>,
 547    window_fullscreen_observations: CallbackCollection<usize, WindowFullscreenCallback>,
 548    window_bounds_observations: CallbackCollection<usize, WindowBoundsCallback>,
 549    keystroke_observations: CallbackCollection<usize, KeystrokeCallback>,
 550    active_labeled_task_observations: CallbackCollection<(), ActiveLabeledTasksCallback>,
 551
 552    foreground: Rc<executor::Foreground>,
 553    pending_effects: VecDeque<Effect>,
 554    pending_notifications: HashSet<usize>,
 555    pending_global_notifications: HashSet<TypeId>,
 556    pending_flushes: usize,
 557    flushing_effects: bool,
 558    halt_action_dispatch: bool,
 559    next_labeled_task_id: usize,
 560    active_labeled_tasks: BTreeMap<usize, &'static str>,
 561}
 562
 563impl AppContext {
 564    fn new(
 565        foreground: Rc<executor::Foreground>,
 566        background: Arc<executor::Background>,
 567        platform: Arc<dyn platform::Platform>,
 568        foreground_platform: Rc<dyn platform::ForegroundPlatform>,
 569        font_cache: Arc<FontCache>,
 570        ref_counts: RefCounts,
 571        asset_source: impl AssetSource,
 572    ) -> Self {
 573        Self {
 574            models: Default::default(),
 575            views: Default::default(),
 576            parents: Default::default(),
 577            windows: Default::default(),
 578            globals: Default::default(),
 579            element_states: Default::default(),
 580            ref_counts: Arc::new(Mutex::new(ref_counts)),
 581            background,
 582
 583            weak_self: None,
 584            font_system: platform.fonts(),
 585            platform,
 586            foreground_platform,
 587            font_cache,
 588            asset_cache: Arc::new(AssetCache::new(asset_source)),
 589            action_deserializers: Default::default(),
 590            capture_actions: Default::default(),
 591            actions: Default::default(),
 592            global_actions: Default::default(),
 593            keystroke_matcher: KeymapMatcher::default(),
 594            next_entity_id: 0,
 595            next_window_id: 0,
 596            next_subscription_id: 0,
 597            frame_count: 0,
 598            subscriptions: Default::default(),
 599            global_subscriptions: Default::default(),
 600            observations: Default::default(),
 601            focus_observations: Default::default(),
 602            release_observations: Default::default(),
 603            global_observations: Default::default(),
 604            window_activation_observations: Default::default(),
 605            window_fullscreen_observations: Default::default(),
 606            window_bounds_observations: Default::default(),
 607            keystroke_observations: Default::default(),
 608            action_dispatch_observations: Default::default(),
 609            active_labeled_task_observations: Default::default(),
 610            foreground,
 611            pending_effects: VecDeque::new(),
 612            pending_notifications: Default::default(),
 613            pending_global_notifications: Default::default(),
 614            pending_flushes: 0,
 615            flushing_effects: false,
 616            halt_action_dispatch: false,
 617            next_labeled_task_id: 0,
 618            active_labeled_tasks: Default::default(),
 619        }
 620    }
 621
 622    pub fn background(&self) -> &Arc<executor::Background> {
 623        &self.background
 624    }
 625
 626    pub fn font_cache(&self) -> &Arc<FontCache> {
 627        &self.font_cache
 628    }
 629
 630    pub fn platform(&self) -> &Arc<dyn Platform> {
 631        &self.platform
 632    }
 633
 634    pub fn has_global<T: 'static>(&self) -> bool {
 635        self.globals.contains_key(&TypeId::of::<T>())
 636    }
 637
 638    pub fn global<T: 'static>(&self) -> &T {
 639        if let Some(global) = self.globals.get(&TypeId::of::<T>()) {
 640            global.downcast_ref().unwrap()
 641        } else {
 642            panic!("no global has been added for {}", type_name::<T>());
 643        }
 644    }
 645
 646    pub fn upgrade(&self) -> App {
 647        App(self.weak_self.as_ref().unwrap().upgrade().unwrap())
 648    }
 649
 650    pub fn quit(&mut self) {
 651        let mut futures = Vec::new();
 652
 653        self.update(|cx| {
 654            for model_id in cx.models.keys().copied().collect::<Vec<_>>() {
 655                let mut model = cx.models.remove(&model_id).unwrap();
 656                futures.extend(model.app_will_quit(cx));
 657                cx.models.insert(model_id, model);
 658            }
 659
 660            for view_id in cx.views.keys().copied().collect::<Vec<_>>() {
 661                let mut view = cx.views.remove(&view_id).unwrap();
 662                futures.extend(view.app_will_quit(cx));
 663                cx.views.insert(view_id, view);
 664            }
 665        });
 666
 667        self.remove_all_windows();
 668
 669        let futures = futures::future::join_all(futures);
 670        if self
 671            .background
 672            .block_with_timeout(Duration::from_millis(100), futures)
 673            .is_err()
 674        {
 675            log::error!("timed out waiting on app_will_quit");
 676        }
 677    }
 678
 679    pub fn remove_all_windows(&mut self) {
 680        self.windows.clear();
 681        self.flush_effects();
 682    }
 683
 684    pub fn foreground(&self) -> &Rc<executor::Foreground> {
 685        &self.foreground
 686    }
 687
 688    pub fn deserialize_action(
 689        &self,
 690        name: &str,
 691        argument: Option<&str>,
 692    ) -> Result<Box<dyn Action>> {
 693        let callback = self
 694            .action_deserializers
 695            .get(name)
 696            .ok_or_else(|| anyhow!("unknown action {}", name))?
 697            .1;
 698        callback(argument.unwrap_or("{}"))
 699            .with_context(|| format!("invalid data for action {}", name))
 700    }
 701
 702    pub fn add_action<A, V, F, R>(&mut self, handler: F)
 703    where
 704        A: Action,
 705        V: View,
 706        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 707    {
 708        self.add_action_internal(handler, false)
 709    }
 710
 711    pub fn capture_action<A, V, F>(&mut self, handler: F)
 712    where
 713        A: Action,
 714        V: View,
 715        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>),
 716    {
 717        self.add_action_internal(handler, true)
 718    }
 719
 720    fn add_action_internal<A, V, F, R>(&mut self, mut handler: F, capture: bool)
 721    where
 722        A: Action,
 723        V: View,
 724        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> R,
 725    {
 726        let handler = Box::new(
 727            move |view: &mut dyn AnyView,
 728                  action: &dyn Action,
 729                  cx: &mut WindowContext,
 730                  view_id: usize| {
 731                let action = action.as_any().downcast_ref().unwrap();
 732                let mut cx = ViewContext::mutable(cx, view_id);
 733                handler(
 734                    view.as_any_mut()
 735                        .downcast_mut()
 736                        .expect("downcast is type safe"),
 737                    action,
 738                    &mut cx,
 739                );
 740            },
 741        );
 742
 743        self.action_deserializers
 744            .entry(A::qualified_name())
 745            .or_insert((TypeId::of::<A>(), A::from_json_str));
 746
 747        let actions = if capture {
 748            &mut self.capture_actions
 749        } else {
 750            &mut self.actions
 751        };
 752
 753        actions
 754            .entry(TypeId::of::<V>())
 755            .or_default()
 756            .entry(TypeId::of::<A>())
 757            .or_default()
 758            .push(handler);
 759    }
 760
 761    pub fn add_async_action<A, V, F>(&mut self, mut handler: F)
 762    where
 763        A: Action,
 764        V: View,
 765        F: 'static + FnMut(&mut V, &A, &mut ViewContext<V>) -> Option<Task<Result<()>>>,
 766    {
 767        self.add_action(move |view, action, cx| {
 768            if let Some(task) = handler(view, action, cx) {
 769                task.detach_and_log_err(cx);
 770            }
 771        })
 772    }
 773
 774    pub fn add_global_action<A, F>(&mut self, mut handler: F)
 775    where
 776        A: Action,
 777        F: 'static + FnMut(&A, &mut AppContext),
 778    {
 779        let handler = Box::new(move |action: &dyn Action, cx: &mut AppContext| {
 780            let action = action.as_any().downcast_ref().unwrap();
 781            handler(action, cx);
 782        });
 783
 784        self.action_deserializers
 785            .entry(A::qualified_name())
 786            .or_insert((TypeId::of::<A>(), A::from_json_str));
 787
 788        if self
 789            .global_actions
 790            .insert(TypeId::of::<A>(), handler)
 791            .is_some()
 792        {
 793            panic!(
 794                "registered multiple global handlers for {}",
 795                type_name::<A>()
 796            );
 797        }
 798    }
 799
 800    pub fn has_window(&self, window_id: usize) -> bool {
 801        self.window_ids()
 802            .find(|window| window == &window_id)
 803            .is_some()
 804    }
 805
 806    pub fn window_is_active(&self, window_id: usize) -> bool {
 807        self.windows.get(&window_id).map_or(false, |w| w.is_active)
 808    }
 809
 810    pub fn root_view(&self, window_id: usize) -> Option<&AnyViewHandle> {
 811        self.windows.get(&window_id).map(|w| w.root_view())
 812    }
 813
 814    pub fn window_ids(&self) -> impl Iterator<Item = usize> + '_ {
 815        self.windows.keys().copied()
 816    }
 817
 818    pub fn view_ui_name(&self, window_id: usize, view_id: usize) -> Option<&'static str> {
 819        Some(self.views.get(&(window_id, view_id))?.ui_name())
 820    }
 821
 822    pub fn view_type_id(&self, window_id: usize, view_id: usize) -> Option<TypeId> {
 823        self.views
 824            .get(&(window_id, view_id))
 825            .map(|view| view.as_any().type_id())
 826    }
 827
 828    /// Returns an iterator over all of the view ids from the passed view up to the root of the window
 829    /// Includes the passed view itself
 830    fn ancestors(&self, window_id: usize, mut view_id: usize) -> impl Iterator<Item = usize> + '_ {
 831        std::iter::once(view_id)
 832            .into_iter()
 833            .chain(std::iter::from_fn(move || {
 834                if let Some(ParentId::View(parent_id)) = self.parents.get(&(window_id, view_id)) {
 835                    view_id = *parent_id;
 836                    Some(view_id)
 837                } else {
 838                    None
 839                }
 840            }))
 841    }
 842
 843    /// Returns the id of the parent of the given view, or none if the given
 844    /// view is the root.
 845    pub fn parent(&self, window_id: usize, view_id: usize) -> Option<usize> {
 846        if let Some(ParentId::View(view_id)) = self.parents.get(&(window_id, view_id)) {
 847            Some(*view_id)
 848        } else {
 849            None
 850        }
 851    }
 852
 853    fn focused_view_id(&self, window_id: usize) -> Option<usize> {
 854        self.windows
 855            .get(&window_id)
 856            .and_then(|window| window.focused_view_id)
 857    }
 858
 859    pub fn is_child_focused(&self, view: &AnyViewHandle) -> bool {
 860        if let Some(focused_view_id) = self.focused_view_id(view.window_id) {
 861            self.ancestors(view.window_id, focused_view_id)
 862                .skip(1) // Skip self id
 863                .any(|parent| parent == view.view_id)
 864        } else {
 865            false
 866        }
 867    }
 868
 869    pub fn active_labeled_tasks<'a>(
 870        &'a self,
 871    ) -> impl DoubleEndedIterator<Item = &'static str> + 'a {
 872        self.active_labeled_tasks.values().cloned()
 873    }
 874
 875    pub(crate) fn start_frame(&mut self) {
 876        self.frame_count += 1;
 877    }
 878
 879    pub fn update<T, F: FnOnce(&mut Self) -> T>(&mut self, callback: F) -> T {
 880        self.pending_flushes += 1;
 881        let result = callback(self);
 882        self.flush_effects();
 883        result
 884    }
 885
 886    pub fn read_window<T, F: FnOnce(&WindowContext) -> T>(
 887        &self,
 888        window_id: usize,
 889        callback: F,
 890    ) -> Option<T> {
 891        let window = self.windows.get(&window_id)?;
 892        let window_context = WindowContext::immutable(self, &window, window_id);
 893        Some(callback(&window_context))
 894    }
 895
 896    pub fn update_window<T, F: FnOnce(&mut WindowContext) -> T>(
 897        &mut self,
 898        window_id: usize,
 899        callback: F,
 900    ) -> Option<T> {
 901        self.update(|app_context| {
 902            let mut window = app_context.windows.remove(&window_id)?;
 903            let mut window_context = WindowContext::mutable(app_context, &mut window, window_id);
 904            let result = callback(&mut window_context);
 905            app_context.windows.insert(window_id, window);
 906            Some(result)
 907        })
 908    }
 909
 910    pub fn prompt_for_paths(
 911        &self,
 912        options: PathPromptOptions,
 913    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
 914        self.foreground_platform.prompt_for_paths(options)
 915    }
 916
 917    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
 918        self.foreground_platform.prompt_for_new_path(directory)
 919    }
 920
 921    pub fn reveal_path(&self, path: &Path) {
 922        self.foreground_platform.reveal_path(path)
 923    }
 924
 925    pub fn emit_global<E: Any>(&mut self, payload: E) {
 926        self.pending_effects.push_back(Effect::GlobalEvent {
 927            payload: Box::new(payload),
 928        });
 929    }
 930
 931    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 932    where
 933        E: Entity,
 934        E::Event: 'static,
 935        H: Handle<E>,
 936        F: 'static + FnMut(H, &E::Event, &mut Self),
 937    {
 938        self.subscribe_internal(handle, move |handle, event, cx| {
 939            callback(handle, event, cx);
 940            true
 941        })
 942    }
 943
 944    pub fn subscribe_global<E, F>(&mut self, mut callback: F) -> Subscription
 945    where
 946        E: Any,
 947        F: 'static + FnMut(&E, &mut Self),
 948    {
 949        let subscription_id = post_inc(&mut self.next_subscription_id);
 950        let type_id = TypeId::of::<E>();
 951        self.pending_effects.push_back(Effect::GlobalSubscription {
 952            type_id,
 953            subscription_id,
 954            callback: Box::new(move |payload, cx| {
 955                let payload = payload.downcast_ref().expect("downcast is type safe");
 956                callback(payload, cx)
 957            }),
 958        });
 959        Subscription::GlobalSubscription(
 960            self.global_subscriptions
 961                .subscribe(type_id, subscription_id),
 962        )
 963    }
 964
 965    pub fn observe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 966    where
 967        E: Entity,
 968        E::Event: 'static,
 969        H: Handle<E>,
 970        F: 'static + FnMut(H, &mut Self),
 971    {
 972        self.observe_internal(handle, move |handle, cx| {
 973            callback(handle, cx);
 974            true
 975        })
 976    }
 977
 978    pub fn subscribe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
 979    where
 980        E: Entity,
 981        E::Event: 'static,
 982        H: Handle<E>,
 983        F: 'static + FnMut(H, &E::Event, &mut Self) -> bool,
 984    {
 985        let subscription_id = post_inc(&mut self.next_subscription_id);
 986        let emitter = handle.downgrade();
 987        self.pending_effects.push_back(Effect::Subscription {
 988            entity_id: handle.id(),
 989            subscription_id,
 990            callback: Box::new(move |payload, cx| {
 991                if let Some(emitter) = H::upgrade_from(&emitter, cx) {
 992                    let payload = payload.downcast_ref().expect("downcast is type safe");
 993                    callback(emitter, payload, cx)
 994                } else {
 995                    false
 996                }
 997            }),
 998        });
 999        Subscription::Subscription(self.subscriptions.subscribe(handle.id(), subscription_id))
1000    }
1001
1002    fn observe_internal<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
1003    where
1004        E: Entity,
1005        E::Event: 'static,
1006        H: Handle<E>,
1007        F: 'static + FnMut(H, &mut Self) -> bool,
1008    {
1009        let subscription_id = post_inc(&mut self.next_subscription_id);
1010        let observed = handle.downgrade();
1011        let entity_id = handle.id();
1012        self.pending_effects.push_back(Effect::Observation {
1013            entity_id,
1014            subscription_id,
1015            callback: Box::new(move |cx| {
1016                if let Some(observed) = H::upgrade_from(&observed, cx) {
1017                    callback(observed, cx)
1018                } else {
1019                    false
1020                }
1021            }),
1022        });
1023        Subscription::Observation(self.observations.subscribe(entity_id, subscription_id))
1024    }
1025
1026    fn observe_focus<F, V>(&mut self, handle: &ViewHandle<V>, mut callback: F) -> Subscription
1027    where
1028        F: 'static + FnMut(ViewHandle<V>, bool, &mut AppContext) -> bool,
1029        V: View,
1030    {
1031        let subscription_id = post_inc(&mut self.next_subscription_id);
1032        let observed = handle.downgrade();
1033        let view_id = handle.id();
1034
1035        self.pending_effects.push_back(Effect::FocusObservation {
1036            view_id,
1037            subscription_id,
1038            callback: Box::new(move |focused, cx| {
1039                if let Some(observed) = observed.upgrade(cx) {
1040                    callback(observed, focused, cx)
1041                } else {
1042                    false
1043                }
1044            }),
1045        });
1046        Subscription::FocusObservation(self.focus_observations.subscribe(view_id, subscription_id))
1047    }
1048
1049    pub fn observe_global<G, F>(&mut self, mut observe: F) -> Subscription
1050    where
1051        G: Any,
1052        F: 'static + FnMut(&mut AppContext),
1053    {
1054        let type_id = TypeId::of::<G>();
1055        let id = post_inc(&mut self.next_subscription_id);
1056
1057        self.global_observations.add_callback(
1058            type_id,
1059            id,
1060            Box::new(move |cx: &mut AppContext| observe(cx)),
1061        );
1062        Subscription::GlobalObservation(self.global_observations.subscribe(type_id, id))
1063    }
1064
1065    pub fn observe_default_global<G, F>(&mut self, observe: F) -> Subscription
1066    where
1067        G: Any + Default,
1068        F: 'static + FnMut(&mut AppContext),
1069    {
1070        if !self.has_global::<G>() {
1071            self.set_global(G::default());
1072        }
1073        self.observe_global::<G, F>(observe)
1074    }
1075
1076    pub fn observe_release<E, H, F>(&mut self, handle: &H, callback: F) -> Subscription
1077    where
1078        E: Entity,
1079        E::Event: 'static,
1080        H: Handle<E>,
1081        F: 'static + FnOnce(&E, &mut Self),
1082    {
1083        let id = post_inc(&mut self.next_subscription_id);
1084        let mut callback = Some(callback);
1085        self.release_observations.add_callback(
1086            handle.id(),
1087            id,
1088            Box::new(move |released, cx| {
1089                let released = released.downcast_ref().unwrap();
1090                if let Some(callback) = callback.take() {
1091                    callback(released, cx)
1092                }
1093            }),
1094        );
1095        Subscription::ReleaseObservation(self.release_observations.subscribe(handle.id(), id))
1096    }
1097
1098    pub fn observe_actions<F>(&mut self, callback: F) -> Subscription
1099    where
1100        F: 'static + FnMut(TypeId, &mut AppContext),
1101    {
1102        let subscription_id = post_inc(&mut self.next_subscription_id);
1103        self.action_dispatch_observations
1104            .add_callback((), subscription_id, Box::new(callback));
1105        Subscription::ActionObservation(
1106            self.action_dispatch_observations
1107                .subscribe((), subscription_id),
1108        )
1109    }
1110
1111    fn observe_window_activation<F>(&mut self, window_id: usize, callback: F) -> Subscription
1112    where
1113        F: 'static + FnMut(bool, &mut AppContext) -> bool,
1114    {
1115        let subscription_id = post_inc(&mut self.next_subscription_id);
1116        self.pending_effects
1117            .push_back(Effect::WindowActivationObservation {
1118                window_id,
1119                subscription_id,
1120                callback: Box::new(callback),
1121            });
1122        Subscription::WindowActivationObservation(
1123            self.window_activation_observations
1124                .subscribe(window_id, subscription_id),
1125        )
1126    }
1127
1128    fn observe_fullscreen<F>(&mut self, window_id: usize, callback: F) -> Subscription
1129    where
1130        F: 'static + FnMut(bool, &mut AppContext) -> bool,
1131    {
1132        let subscription_id = post_inc(&mut self.next_subscription_id);
1133        self.pending_effects
1134            .push_back(Effect::WindowFullscreenObservation {
1135                window_id,
1136                subscription_id,
1137                callback: Box::new(callback),
1138            });
1139        Subscription::WindowActivationObservation(
1140            self.window_activation_observations
1141                .subscribe(window_id, subscription_id),
1142        )
1143    }
1144
1145    fn observe_window_bounds<F>(&mut self, window_id: usize, callback: F) -> Subscription
1146    where
1147        F: 'static + FnMut(WindowBounds, Uuid, &mut AppContext) -> bool,
1148    {
1149        let subscription_id = post_inc(&mut self.next_subscription_id);
1150        self.pending_effects
1151            .push_back(Effect::WindowBoundsObservation {
1152                window_id,
1153                subscription_id,
1154                callback: Box::new(callback),
1155            });
1156        Subscription::WindowBoundsObservation(
1157            self.window_bounds_observations
1158                .subscribe(window_id, subscription_id),
1159        )
1160    }
1161
1162    pub fn observe_keystrokes<F>(&mut self, window_id: usize, callback: F) -> Subscription
1163    where
1164        F: 'static
1165            + FnMut(&Keystroke, &MatchResult, Option<&Box<dyn Action>>, &mut AppContext) -> bool,
1166    {
1167        let subscription_id = post_inc(&mut self.next_subscription_id);
1168        self.keystroke_observations
1169            .add_callback(window_id, subscription_id, Box::new(callback));
1170        Subscription::KeystrokeObservation(
1171            self.keystroke_observations
1172                .subscribe(window_id, subscription_id),
1173        )
1174    }
1175
1176    pub fn observe_active_labeled_tasks<F>(&mut self, callback: F) -> Subscription
1177    where
1178        F: 'static + FnMut(&mut AppContext) -> bool,
1179    {
1180        let subscription_id = post_inc(&mut self.next_subscription_id);
1181        self.active_labeled_task_observations
1182            .add_callback((), subscription_id, Box::new(callback));
1183        Subscription::ActiveLabeledTasksObservation(
1184            self.active_labeled_task_observations
1185                .subscribe((), subscription_id),
1186        )
1187    }
1188
1189    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1190        self.pending_effects.push_back(Effect::Deferred {
1191            callback: Box::new(callback),
1192            after_window_update: false,
1193        })
1194    }
1195
1196    pub fn after_window_update(&mut self, callback: impl 'static + FnOnce(&mut AppContext)) {
1197        self.pending_effects.push_back(Effect::Deferred {
1198            callback: Box::new(callback),
1199            after_window_update: true,
1200        })
1201    }
1202
1203    pub(crate) fn notify_model(&mut self, model_id: usize) {
1204        if self.pending_notifications.insert(model_id) {
1205            self.pending_effects
1206                .push_back(Effect::ModelNotification { model_id });
1207        }
1208    }
1209
1210    pub(crate) fn notify_view(&mut self, window_id: usize, view_id: usize) {
1211        if self.pending_notifications.insert(view_id) {
1212            self.pending_effects
1213                .push_back(Effect::ViewNotification { window_id, view_id });
1214        }
1215    }
1216
1217    pub(crate) fn notify_global(&mut self, type_id: TypeId) {
1218        if self.pending_global_notifications.insert(type_id) {
1219            self.pending_effects
1220                .push_back(Effect::GlobalNotification { type_id });
1221        }
1222    }
1223
1224    pub(crate) fn name_for_view(&self, window_id: usize, view_id: usize) -> Option<&str> {
1225        self.views
1226            .get(&(window_id, view_id))
1227            .map(|view| view.ui_name())
1228    }
1229
1230    pub fn all_action_names<'a>(&'a self) -> impl Iterator<Item = &'static str> + 'a {
1231        self.action_deserializers.keys().copied()
1232    }
1233
1234    /// Return keystrokes that would dispatch the given action on the given view.
1235    pub(crate) fn keystrokes_for_action(
1236        &mut self,
1237        window_id: usize,
1238        view_id: usize,
1239        action: &dyn Action,
1240    ) -> Option<SmallVec<[Keystroke; 2]>> {
1241        let mut contexts = Vec::new();
1242        let mut handler_depth = None;
1243        for (i, view_id) in self.ancestors(window_id, view_id).enumerate() {
1244            if let Some(view) = self.views.get(&(window_id, view_id)) {
1245                if let Some(actions) = self.actions.get(&view.as_any().type_id()) {
1246                    if actions.contains_key(&action.as_any().type_id()) {
1247                        handler_depth = Some(i);
1248                    }
1249                }
1250                contexts.push(view.keymap_context(self));
1251            }
1252        }
1253
1254        if self.global_actions.contains_key(&action.as_any().type_id()) {
1255            handler_depth = Some(contexts.len())
1256        }
1257
1258        self.keystroke_matcher
1259            .bindings_for_action_type(action.as_any().type_id())
1260            .find_map(|b| {
1261                handler_depth
1262                    .map(|highest_handler| {
1263                        if (0..=highest_handler).any(|depth| b.match_context(&contexts[depth..])) {
1264                            Some(b.keystrokes().into())
1265                        } else {
1266                            None
1267                        }
1268                    })
1269                    .flatten()
1270            })
1271    }
1272
1273    pub fn available_actions(
1274        &self,
1275        window_id: usize,
1276        view_id: usize,
1277    ) -> impl Iterator<Item = (&'static str, Box<dyn Action>, SmallVec<[&Binding; 1]>)> {
1278        let mut contexts = Vec::new();
1279        let mut handler_depths_by_action_type = HashMap::<TypeId, usize>::default();
1280        for (depth, view_id) in self.ancestors(window_id, view_id).enumerate() {
1281            if let Some(view) = self.views.get(&(window_id, view_id)) {
1282                contexts.push(view.keymap_context(self));
1283                let view_type = view.as_any().type_id();
1284                if let Some(actions) = self.actions.get(&view_type) {
1285                    handler_depths_by_action_type.extend(
1286                        actions
1287                            .keys()
1288                            .copied()
1289                            .map(|action_type| (action_type, depth)),
1290                    );
1291                }
1292            }
1293        }
1294
1295        handler_depths_by_action_type.extend(
1296            self.global_actions
1297                .keys()
1298                .copied()
1299                .map(|action_type| (action_type, contexts.len())),
1300        );
1301
1302        self.action_deserializers
1303            .iter()
1304            .filter_map(move |(name, (type_id, deserialize))| {
1305                if let Some(action_depth) = handler_depths_by_action_type.get(type_id).copied() {
1306                    Some((
1307                        *name,
1308                        deserialize("{}").ok()?,
1309                        self.keystroke_matcher
1310                            .bindings_for_action_type(*type_id)
1311                            .filter(|b| {
1312                                (0..=action_depth).any(|depth| b.match_context(&contexts[depth..]))
1313                            })
1314                            .collect(),
1315                    ))
1316                } else {
1317                    None
1318                }
1319            })
1320    }
1321
1322    pub fn is_action_available(&self, action: &dyn Action) -> bool {
1323        let action_type = action.as_any().type_id();
1324        if let Some(window_id) = self.platform.main_window_id() {
1325            if let Some(focused_view_id) = self.focused_view_id(window_id) {
1326                for view_id in self.ancestors(window_id, focused_view_id) {
1327                    if let Some(view) = self.views.get(&(window_id, view_id)) {
1328                        let view_type = view.as_any().type_id();
1329                        if let Some(actions) = self.actions.get(&view_type) {
1330                            if actions.contains_key(&action_type) {
1331                                return true;
1332                            }
1333                        }
1334                    }
1335                }
1336            }
1337        }
1338        self.global_actions.contains_key(&action_type)
1339    }
1340
1341    // Traverses the parent tree. Walks down the tree toward the passed
1342    // view calling visit with true. Then walks back up the tree calling visit with false.
1343    // If `visit` returns false this function will immediately return.
1344    // Returns a bool indicating if the traversal was completed early.
1345    fn visit_dispatch_path(
1346        &mut self,
1347        window_id: usize,
1348        view_id: usize,
1349        mut visit: impl FnMut(usize, bool, &mut AppContext) -> bool,
1350    ) -> bool {
1351        // List of view ids from the leaf to the root of the window
1352        let path = self.ancestors(window_id, view_id).collect::<Vec<_>>();
1353
1354        // Walk down from the root to the leaf calling visit with capture_phase = true
1355        for view_id in path.iter().rev() {
1356            if !visit(*view_id, true, self) {
1357                return false;
1358            }
1359        }
1360
1361        // Walk up from the leaf to the root calling visit with capture_phase = false
1362        for view_id in path.iter() {
1363            if !visit(*view_id, false, self) {
1364                return false;
1365            }
1366        }
1367
1368        true
1369    }
1370
1371    fn actions_mut(
1372        &mut self,
1373        capture_phase: bool,
1374    ) -> &mut HashMap<TypeId, HashMap<TypeId, Vec<Box<ActionCallback>>>> {
1375        if capture_phase {
1376            &mut self.capture_actions
1377        } else {
1378            &mut self.actions
1379        }
1380    }
1381
1382    pub fn dispatch_global_action<A: Action>(&mut self, action: A) {
1383        self.dispatch_global_action_any(&action);
1384    }
1385
1386    fn dispatch_global_action_any(&mut self, action: &dyn Action) -> bool {
1387        self.update(|this| {
1388            if let Some((name, mut handler)) = this.global_actions.remove_entry(&action.id()) {
1389                handler(action, this);
1390                this.global_actions.insert(name, handler);
1391                true
1392            } else {
1393                false
1394            }
1395        })
1396    }
1397
1398    pub fn add_bindings<T: IntoIterator<Item = Binding>>(&mut self, bindings: T) {
1399        self.keystroke_matcher.add_bindings(bindings);
1400    }
1401
1402    pub fn clear_bindings(&mut self) {
1403        self.keystroke_matcher.clear_bindings();
1404    }
1405
1406    pub fn default_global<T: 'static + Default>(&mut self) -> &T {
1407        let type_id = TypeId::of::<T>();
1408        self.update(|this| {
1409            if let Entry::Vacant(entry) = this.globals.entry(type_id) {
1410                entry.insert(Box::new(T::default()));
1411                this.notify_global(type_id);
1412            }
1413        });
1414        self.globals.get(&type_id).unwrap().downcast_ref().unwrap()
1415    }
1416
1417    pub fn set_global<T: 'static>(&mut self, state: T) {
1418        self.update(|this| {
1419            let type_id = TypeId::of::<T>();
1420            this.globals.insert(type_id, Box::new(state));
1421            this.notify_global(type_id);
1422        });
1423    }
1424
1425    pub fn update_default_global<T, F, U>(&mut self, update: F) -> U
1426    where
1427        T: 'static + Default,
1428        F: FnOnce(&mut T, &mut AppContext) -> U,
1429    {
1430        self.update(|this| {
1431            let type_id = TypeId::of::<T>();
1432            let mut state = this
1433                .globals
1434                .remove(&type_id)
1435                .unwrap_or_else(|| Box::new(T::default()));
1436            let result = update(state.downcast_mut().unwrap(), this);
1437            this.globals.insert(type_id, state);
1438            this.notify_global(type_id);
1439            result
1440        })
1441    }
1442
1443    pub fn update_global<T, F, U>(&mut self, update: F) -> U
1444    where
1445        T: 'static,
1446        F: FnOnce(&mut T, &mut AppContext) -> U,
1447    {
1448        self.update(|this| {
1449            let type_id = TypeId::of::<T>();
1450            if let Some(mut state) = this.globals.remove(&type_id) {
1451                let result = update(state.downcast_mut().unwrap(), this);
1452                this.globals.insert(type_id, state);
1453                this.notify_global(type_id);
1454                result
1455            } else {
1456                panic!("No global added for {}", std::any::type_name::<T>());
1457            }
1458        })
1459    }
1460
1461    pub fn clear_globals(&mut self) {
1462        self.globals.clear();
1463    }
1464
1465    pub fn add_model<T, F>(&mut self, build_model: F) -> ModelHandle<T>
1466    where
1467        T: Entity,
1468        F: FnOnce(&mut ModelContext<T>) -> T,
1469    {
1470        self.update(|this| {
1471            let model_id = post_inc(&mut this.next_entity_id);
1472            let handle = ModelHandle::new(model_id, &this.ref_counts);
1473            let mut cx = ModelContext::new(this, model_id);
1474            let model = build_model(&mut cx);
1475            this.models.insert(model_id, Box::new(model));
1476            handle
1477        })
1478    }
1479
1480    pub fn add_window<V, F>(
1481        &mut self,
1482        window_options: WindowOptions,
1483        build_root_view: F,
1484    ) -> (usize, ViewHandle<V>)
1485    where
1486        V: View,
1487        F: FnOnce(&mut ViewContext<V>) -> V,
1488    {
1489        self.update(|this| {
1490            let window_id = post_inc(&mut this.next_window_id);
1491            let platform_window =
1492                this.platform
1493                    .open_window(window_id, window_options, this.foreground.clone());
1494            let window = this.build_window(window_id, platform_window, build_root_view);
1495            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1496
1497            this.windows.insert(window_id, window);
1498            root_view.update(this, |view, cx| view.focus_in(cx.handle().into_any(), cx));
1499
1500            (window_id, root_view)
1501        })
1502    }
1503
1504    pub fn add_status_bar_item<V, F>(&mut self, build_root_view: F) -> (usize, ViewHandle<V>)
1505    where
1506        V: View,
1507        F: FnOnce(&mut ViewContext<V>) -> V,
1508    {
1509        self.update(|this| {
1510            let window_id = post_inc(&mut this.next_window_id);
1511            let platform_window = this.platform.add_status_item();
1512            let window = this.build_window(window_id, platform_window, build_root_view);
1513            let root_view = window.root_view().clone().downcast::<V>().unwrap();
1514
1515            this.windows.insert(window_id, window);
1516            root_view.update(this, |view, cx| view.focus_in(cx.handle().into_any(), cx));
1517
1518            (window_id, root_view)
1519        })
1520    }
1521
1522    pub fn remove_status_bar_item(&mut self, id: usize) {
1523        self.remove_window(id);
1524    }
1525
1526    pub fn remove_window(&mut self, window_id: usize) {
1527        self.windows.remove(&window_id);
1528        self.flush_effects();
1529    }
1530
1531    pub fn build_window<V, F>(
1532        &mut self,
1533        window_id: usize,
1534        mut platform_window: Box<dyn platform::Window>,
1535        build_root_view: F,
1536    ) -> Window
1537    where
1538        V: View,
1539        F: FnOnce(&mut ViewContext<V>) -> V,
1540    {
1541        {
1542            let mut app = self.upgrade();
1543
1544            platform_window.on_event(Box::new(move |event| {
1545                app.update_window(window_id, |cx| {
1546                    if let Event::KeyDown(KeyDownEvent { keystroke, .. }) = &event {
1547                        if cx.dispatch_keystroke(keystroke) {
1548                            return true;
1549                        }
1550                    }
1551
1552                    cx.dispatch_event(event, false)
1553                })
1554                .unwrap_or(false)
1555            }));
1556        }
1557
1558        {
1559            let mut app = self.upgrade();
1560            platform_window.on_active_status_change(Box::new(move |is_active| {
1561                app.update(|cx| cx.window_changed_active_status(window_id, is_active))
1562            }));
1563        }
1564
1565        {
1566            let mut app = self.upgrade();
1567            platform_window.on_resize(Box::new(move || {
1568                app.update(|cx| cx.window_was_resized(window_id))
1569            }));
1570        }
1571
1572        {
1573            let mut app = self.upgrade();
1574            platform_window.on_moved(Box::new(move || {
1575                app.update(|cx| cx.window_was_moved(window_id))
1576            }));
1577        }
1578
1579        {
1580            let mut app = self.upgrade();
1581            platform_window.on_fullscreen(Box::new(move |is_fullscreen| {
1582                app.update(|cx| cx.window_was_fullscreen_changed(window_id, is_fullscreen))
1583            }));
1584        }
1585
1586        {
1587            let mut app = self.upgrade();
1588            platform_window.on_close(Box::new(move || {
1589                app.update(|cx| cx.remove_window(window_id));
1590            }));
1591        }
1592
1593        {
1594            let mut app = self.upgrade();
1595            platform_window
1596                .on_appearance_changed(Box::new(move || app.update(|cx| cx.refresh_windows())));
1597        }
1598
1599        platform_window.set_input_handler(Box::new(WindowInputHandler {
1600            app: self.upgrade().0,
1601            window_id,
1602        }));
1603
1604        let mut window = Window::new(window_id, platform_window, self, build_root_view);
1605        let scene = WindowContext::mutable(self, &mut window, window_id).build_scene();
1606        window.platform_window.present_scene(scene);
1607        window
1608    }
1609
1610    pub fn replace_root_view<V, F>(
1611        &mut self,
1612        window_id: usize,
1613        build_root_view: F,
1614    ) -> Option<ViewHandle<V>>
1615    where
1616        V: View,
1617        F: FnOnce(&mut ViewContext<V>) -> V,
1618    {
1619        self.update_window(window_id, |cx| cx.replace_root_view(build_root_view))
1620    }
1621
1622    pub fn add_view<S, F>(&mut self, parent: &AnyViewHandle, build_view: F) -> ViewHandle<S>
1623    where
1624        S: View,
1625        F: FnOnce(&mut ViewContext<S>) -> S,
1626    {
1627        self.update_window(parent.window_id, |cx| {
1628            cx.build_and_insert_view(ParentId::View(parent.view_id), |cx| Some(build_view(cx)))
1629                .unwrap()
1630        })
1631        .unwrap()
1632    }
1633
1634    fn remove_dropped_entities(&mut self) {
1635        loop {
1636            let (dropped_models, dropped_views, dropped_element_states) =
1637                self.ref_counts.lock().take_dropped();
1638            if dropped_models.is_empty()
1639                && dropped_views.is_empty()
1640                && dropped_element_states.is_empty()
1641            {
1642                break;
1643            }
1644
1645            for model_id in dropped_models {
1646                self.subscriptions.remove(model_id);
1647                self.observations.remove(model_id);
1648                let mut model = self.models.remove(&model_id).unwrap();
1649                model.release(self);
1650                self.pending_effects
1651                    .push_back(Effect::ModelRelease { model_id, model });
1652            }
1653
1654            for (window_id, view_id) in dropped_views {
1655                self.subscriptions.remove(view_id);
1656                self.observations.remove(view_id);
1657                let mut view = self.views.remove(&(window_id, view_id)).unwrap();
1658                view.release(self);
1659                let change_focus_to = self.windows.get_mut(&window_id).and_then(|window| {
1660                    window
1661                        .invalidation
1662                        .get_or_insert_with(Default::default)
1663                        .removed
1664                        .push(view_id);
1665                    if window.focused_view_id == Some(view_id) {
1666                        Some(window.root_view().id())
1667                    } else {
1668                        None
1669                    }
1670                });
1671                self.parents.remove(&(window_id, view_id));
1672
1673                if let Some(view_id) = change_focus_to {
1674                    self.handle_focus_effect(window_id, Some(view_id));
1675                }
1676
1677                self.pending_effects
1678                    .push_back(Effect::ViewRelease { view_id, view });
1679            }
1680
1681            for key in dropped_element_states {
1682                self.element_states.remove(&key);
1683            }
1684        }
1685    }
1686
1687    fn flush_effects(&mut self) {
1688        self.pending_flushes = self.pending_flushes.saturating_sub(1);
1689        let mut after_window_update_callbacks = Vec::new();
1690
1691        if !self.flushing_effects && self.pending_flushes == 0 {
1692            self.flushing_effects = true;
1693
1694            let mut refreshing = false;
1695            loop {
1696                if let Some(effect) = self.pending_effects.pop_front() {
1697                    match effect {
1698                        Effect::Subscription {
1699                            entity_id,
1700                            subscription_id,
1701                            callback,
1702                        } => self
1703                            .subscriptions
1704                            .add_callback(entity_id, subscription_id, callback),
1705
1706                        Effect::Event { entity_id, payload } => {
1707                            let mut subscriptions = self.subscriptions.clone();
1708                            subscriptions.emit(entity_id, self, |callback, this| {
1709                                callback(payload.as_ref(), this)
1710                            })
1711                        }
1712
1713                        Effect::GlobalSubscription {
1714                            type_id,
1715                            subscription_id,
1716                            callback,
1717                        } => self.global_subscriptions.add_callback(
1718                            type_id,
1719                            subscription_id,
1720                            callback,
1721                        ),
1722
1723                        Effect::GlobalEvent { payload } => self.emit_global_event(payload),
1724
1725                        Effect::Observation {
1726                            entity_id,
1727                            subscription_id,
1728                            callback,
1729                        } => self
1730                            .observations
1731                            .add_callback(entity_id, subscription_id, callback),
1732
1733                        Effect::ModelNotification { model_id } => {
1734                            let mut observations = self.observations.clone();
1735                            observations.emit(model_id, self, |callback, this| callback(this));
1736                        }
1737
1738                        Effect::ViewNotification { window_id, view_id } => {
1739                            self.handle_view_notification_effect(window_id, view_id)
1740                        }
1741
1742                        Effect::GlobalNotification { type_id } => {
1743                            let mut subscriptions = self.global_observations.clone();
1744                            subscriptions.emit(type_id, self, |callback, this| {
1745                                callback(this);
1746                                true
1747                            });
1748                        }
1749
1750                        Effect::Deferred {
1751                            callback,
1752                            after_window_update,
1753                        } => {
1754                            if after_window_update {
1755                                after_window_update_callbacks.push(callback);
1756                            } else {
1757                                callback(self)
1758                            }
1759                        }
1760
1761                        Effect::ModelRelease { model_id, model } => {
1762                            self.handle_entity_release_effect(model_id, model.as_any())
1763                        }
1764
1765                        Effect::ViewRelease { view_id, view } => {
1766                            self.handle_entity_release_effect(view_id, view.as_any())
1767                        }
1768
1769                        Effect::Focus { window_id, view_id } => {
1770                            self.handle_focus_effect(window_id, view_id);
1771                        }
1772
1773                        Effect::FocusObservation {
1774                            view_id,
1775                            subscription_id,
1776                            callback,
1777                        } => {
1778                            self.focus_observations.add_callback(
1779                                view_id,
1780                                subscription_id,
1781                                callback,
1782                            );
1783                        }
1784
1785                        Effect::ResizeWindow { window_id } => {
1786                            if let Some(window) = self.windows.get_mut(&window_id) {
1787                                window
1788                                    .invalidation
1789                                    .get_or_insert(WindowInvalidation::default());
1790                            }
1791                            self.handle_window_moved(window_id);
1792                        }
1793
1794                        Effect::MoveWindow { window_id } => {
1795                            self.handle_window_moved(window_id);
1796                        }
1797
1798                        Effect::WindowActivationObservation {
1799                            window_id,
1800                            subscription_id,
1801                            callback,
1802                        } => self.window_activation_observations.add_callback(
1803                            window_id,
1804                            subscription_id,
1805                            callback,
1806                        ),
1807
1808                        Effect::ActivateWindow {
1809                            window_id,
1810                            is_active,
1811                        } => self.handle_window_activation_effect(window_id, is_active),
1812
1813                        Effect::WindowFullscreenObservation {
1814                            window_id,
1815                            subscription_id,
1816                            callback,
1817                        } => self.window_fullscreen_observations.add_callback(
1818                            window_id,
1819                            subscription_id,
1820                            callback,
1821                        ),
1822
1823                        Effect::FullscreenWindow {
1824                            window_id,
1825                            is_fullscreen,
1826                        } => self.handle_fullscreen_effect(window_id, is_fullscreen),
1827
1828                        Effect::WindowBoundsObservation {
1829                            window_id,
1830                            subscription_id,
1831                            callback,
1832                        } => self.window_bounds_observations.add_callback(
1833                            window_id,
1834                            subscription_id,
1835                            callback,
1836                        ),
1837
1838                        Effect::RefreshWindows => {
1839                            refreshing = true;
1840                        }
1841                        Effect::DispatchActionFrom {
1842                            window_id,
1843                            view_id,
1844                            action,
1845                        } => {
1846                            self.handle_dispatch_action_from_effect(
1847                                window_id,
1848                                Some(view_id),
1849                                action.as_ref(),
1850                            );
1851                        }
1852                        Effect::ActionDispatchNotification { action_id } => {
1853                            self.handle_action_dispatch_notification_effect(action_id)
1854                        }
1855                        Effect::WindowShouldCloseSubscription {
1856                            window_id,
1857                            callback,
1858                        } => {
1859                            self.handle_window_should_close_subscription_effect(window_id, callback)
1860                        }
1861                        Effect::Keystroke {
1862                            window_id,
1863                            keystroke,
1864                            handled_by,
1865                            result,
1866                        } => self.handle_keystroke_effect(window_id, keystroke, handled_by, result),
1867                        Effect::ActiveLabeledTasksChanged => {
1868                            self.handle_active_labeled_tasks_changed_effect()
1869                        }
1870                        Effect::ActiveLabeledTasksObservation {
1871                            subscription_id,
1872                            callback,
1873                        } => self.active_labeled_task_observations.add_callback(
1874                            (),
1875                            subscription_id,
1876                            callback,
1877                        ),
1878                    }
1879                    self.pending_notifications.clear();
1880                    self.remove_dropped_entities();
1881                } else {
1882                    self.remove_dropped_entities();
1883
1884                    if refreshing {
1885                        self.perform_window_refresh();
1886                    } else {
1887                        self.update_windows();
1888                    }
1889
1890                    if self.pending_effects.is_empty() {
1891                        for callback in after_window_update_callbacks.drain(..) {
1892                            callback(self);
1893                        }
1894
1895                        if self.pending_effects.is_empty() {
1896                            self.flushing_effects = false;
1897                            self.pending_notifications.clear();
1898                            self.pending_global_notifications.clear();
1899                            break;
1900                        }
1901                    }
1902
1903                    refreshing = false;
1904                }
1905            }
1906        }
1907    }
1908
1909    fn update_windows(&mut self) {
1910        let window_ids = self.windows.keys().cloned().collect::<Vec<_>>();
1911        for window_id in window_ids {
1912            self.update_window(window_id, |cx| {
1913                if let Some(mut invalidation) = cx.window.invalidation.take() {
1914                    let appearance = cx.window.platform_window.appearance();
1915                    cx.invalidate(&mut invalidation, appearance);
1916                    let scene = cx.build_scene();
1917                    cx.window.platform_window.present_scene(scene);
1918                }
1919            });
1920        }
1921    }
1922
1923    fn window_was_resized(&mut self, window_id: usize) {
1924        self.pending_effects
1925            .push_back(Effect::ResizeWindow { window_id });
1926    }
1927
1928    fn window_was_moved(&mut self, window_id: usize) {
1929        self.pending_effects
1930            .push_back(Effect::MoveWindow { window_id });
1931    }
1932
1933    fn window_was_fullscreen_changed(&mut self, window_id: usize, is_fullscreen: bool) {
1934        self.pending_effects.push_back(Effect::FullscreenWindow {
1935            window_id,
1936            is_fullscreen,
1937        });
1938    }
1939
1940    fn window_changed_active_status(&mut self, window_id: usize, is_active: bool) {
1941        self.pending_effects.push_back(Effect::ActivateWindow {
1942            window_id,
1943            is_active,
1944        });
1945    }
1946
1947    fn keystroke(
1948        &mut self,
1949        window_id: usize,
1950        keystroke: Keystroke,
1951        handled_by: Option<Box<dyn Action>>,
1952        result: MatchResult,
1953    ) {
1954        self.pending_effects.push_back(Effect::Keystroke {
1955            window_id,
1956            keystroke,
1957            handled_by,
1958            result,
1959        });
1960    }
1961
1962    pub fn refresh_windows(&mut self) {
1963        self.pending_effects.push_back(Effect::RefreshWindows);
1964    }
1965
1966    pub fn dispatch_action_at(&mut self, window_id: usize, view_id: usize, action: impl Action) {
1967        self.dispatch_any_action_at(window_id, view_id, Box::new(action));
1968    }
1969
1970    pub fn dispatch_any_action_at(
1971        &mut self,
1972        window_id: usize,
1973        view_id: usize,
1974        action: Box<dyn Action>,
1975    ) {
1976        self.pending_effects.push_back(Effect::DispatchActionFrom {
1977            window_id,
1978            view_id,
1979            action,
1980        });
1981    }
1982
1983    fn perform_window_refresh(&mut self) {
1984        let window_ids = self.windows.keys().cloned().collect::<Vec<_>>();
1985        for window_id in window_ids {
1986            self.update_window(window_id, |cx| {
1987                let mut invalidation = cx.window.invalidation.take().unwrap_or_default();
1988                invalidation
1989                    .updated
1990                    .extend(cx.window.rendered_views.keys().copied());
1991                cx.invalidate(&mut invalidation, cx.window.platform_window.appearance());
1992                cx.refreshing = true;
1993                let scene = cx.build_scene();
1994                cx.window.platform_window.present_scene(scene);
1995            });
1996        }
1997    }
1998
1999    fn emit_global_event(&mut self, payload: Box<dyn Any>) {
2000        let type_id = (&*payload).type_id();
2001
2002        let mut subscriptions = self.global_subscriptions.clone();
2003        subscriptions.emit(type_id, self, |callback, this| {
2004            callback(payload.as_ref(), this);
2005            true //Always alive
2006        });
2007    }
2008
2009    fn handle_view_notification_effect(
2010        &mut self,
2011        observed_window_id: usize,
2012        observed_view_id: usize,
2013    ) {
2014        if self
2015            .views
2016            .contains_key(&(observed_window_id, observed_view_id))
2017        {
2018            if let Some(window) = self.windows.get_mut(&observed_window_id) {
2019                window
2020                    .invalidation
2021                    .get_or_insert_with(Default::default)
2022                    .updated
2023                    .insert(observed_view_id);
2024            }
2025
2026            let mut observations = self.observations.clone();
2027            observations.emit(observed_view_id, self, |callback, this| callback(this));
2028        }
2029    }
2030
2031    fn handle_entity_release_effect(&mut self, entity_id: usize, entity: &dyn Any) {
2032        self.release_observations
2033            .clone()
2034            .emit(entity_id, self, |callback, this| {
2035                callback(entity, this);
2036                // Release observations happen one time. So clear the callback by returning false
2037                false
2038            })
2039    }
2040
2041    fn handle_fullscreen_effect(&mut self, window_id: usize, is_fullscreen: bool) {
2042        self.update_window(window_id, |cx| {
2043            cx.window.is_fullscreen = is_fullscreen;
2044
2045            let mut fullscreen_observations = cx.window_fullscreen_observations.clone();
2046            fullscreen_observations.emit(window_id, cx, |callback, this| {
2047                callback(is_fullscreen, this)
2048            });
2049
2050            if let Some(uuid) = cx.window_display_uuid() {
2051                let bounds = cx.window_bounds();
2052                let mut bounds_observations = cx.window_bounds_observations.clone();
2053                bounds_observations
2054                    .emit(window_id, cx, |callback, this| callback(bounds, uuid, this));
2055            }
2056
2057            Some(())
2058        });
2059    }
2060
2061    fn handle_keystroke_effect(
2062        &mut self,
2063        window_id: usize,
2064        keystroke: Keystroke,
2065        handled_by: Option<Box<dyn Action>>,
2066        result: MatchResult,
2067    ) {
2068        self.update(|this| {
2069            let mut observations = this.keystroke_observations.clone();
2070            observations.emit(window_id, this, {
2071                move |callback, this| callback(&keystroke, &result, handled_by.as_ref(), this)
2072            });
2073        });
2074    }
2075
2076    fn handle_window_activation_effect(&mut self, window_id: usize, active: bool) {
2077        //Short circuit evaluation if we're already g2g
2078        if self
2079            .windows
2080            .get(&window_id)
2081            .map(|w| w.is_active == active)
2082            .unwrap_or(false)
2083        {
2084            return;
2085        }
2086
2087        self.update(|cx| {
2088            cx.update_window(window_id, |cx| {
2089                let Some(focused_id) = cx.window.focused_view_id else {
2090                    return;
2091                };
2092
2093                for view_id in cx.ancestors(window_id, focused_id).collect::<Vec<_>>() {
2094                    cx.update_any_view(focused_id, |view, cx| {
2095                        if active {
2096                            view.focus_in(focused_id, cx, view_id);
2097                        } else {
2098                            view.focus_out(focused_id, cx, view_id);
2099                        }
2100                    });
2101                }
2102            });
2103
2104            let mut observations = cx.window_activation_observations.clone();
2105            observations.emit(window_id, cx, |callback, this| callback(active, this));
2106
2107            Some(())
2108        });
2109    }
2110
2111    fn handle_focus_effect(&mut self, window_id: usize, focused_id: Option<usize>) {
2112        todo!()
2113        // if self
2114        //     .windows
2115        //     .get(&window_id)
2116        //     .map(|w| w.focused_view_id)
2117        //     .map_or(false, |cur_focused| cur_focused == focused_id)
2118        // {
2119        //     return;
2120        // }
2121
2122        // self.update(|this| {
2123        //     let blurred_id = this.windows.get_mut(&window_id).and_then(|window| {
2124        //         let blurred_id = window.focused_view_id;
2125        //         window.focused_view_id = focused_id;
2126        //         blurred_id
2127        //     });
2128
2129        //     let blurred_parents = blurred_id
2130        //         .map(|blurred_id| this.ancestors(window_id, blurred_id).collect::<Vec<_>>())
2131        //         .unwrap_or_default();
2132        //     let focused_parents = focused_id
2133        //         .map(|focused_id| this.ancestors(window_id, focused_id).collect::<Vec<_>>())
2134        //         .unwrap_or_default();
2135
2136        //     if let Some(blurred_id) = blurred_id {
2137        //         for view_id in blurred_parents.iter().copied() {
2138        //             if let Some(mut view) = this.views.remove(&(window_id, view_id)) {
2139        //                 view.focus_out(this, window_id, view_id, blurred_id);
2140        //                 this.views.insert((window_id, view_id), view);
2141        //             }
2142        //         }
2143
2144        //         let mut subscriptions = this.focus_observations.clone();
2145        //         subscriptions.emit(blurred_id, this, |callback, this| callback(false, this));
2146        //     }
2147
2148        //     if let Some(focused_id) = focused_id {
2149        //         for view_id in focused_parents {
2150        //             if let Some(mut view) = this.views.remove(&(window_id, view_id)) {
2151        //                 view.focus_in(this, window_id, view_id, focused_id);
2152        //                 this.views.insert((window_id, view_id), view);
2153        //             }
2154        //         }
2155
2156        //         let mut subscriptions = this.focus_observations.clone();
2157        //         subscriptions.emit(focused_id, this, |callback, this| callback(true, this));
2158        //     }
2159        // })
2160    }
2161
2162    fn handle_dispatch_action_from_effect(
2163        &mut self,
2164        window_id: usize,
2165        view_id: Option<usize>,
2166        action: &dyn Action,
2167    ) -> bool {
2168        self.update(|this| {
2169            if let Some(view_id) = view_id {
2170                this.halt_action_dispatch = false;
2171                this.visit_dispatch_path(window_id, view_id, |view_id, capture_phase, this| {
2172                    this.update_window(window_id, |cx| {
2173                        cx.update_any_view(view_id, |view, cx| {
2174                            let type_id = view.as_any().type_id();
2175                            if let Some((name, mut handlers)) = cx
2176                                .actions_mut(capture_phase)
2177                                .get_mut(&type_id)
2178                                .and_then(|h| h.remove_entry(&action.id()))
2179                            {
2180                                for handler in handlers.iter_mut().rev() {
2181                                    cx.halt_action_dispatch = true;
2182                                    handler(view, action, cx, view_id);
2183                                    if cx.halt_action_dispatch {
2184                                        break;
2185                                    }
2186                                }
2187                                cx.actions_mut(capture_phase)
2188                                    .get_mut(&type_id)
2189                                    .unwrap()
2190                                    .insert(name, handlers);
2191                            }
2192                        })
2193                    });
2194
2195                    !this.halt_action_dispatch
2196                });
2197            }
2198
2199            if !this.halt_action_dispatch {
2200                this.halt_action_dispatch = this.dispatch_global_action_any(action);
2201            }
2202
2203            this.pending_effects
2204                .push_back(Effect::ActionDispatchNotification {
2205                    action_id: action.id(),
2206                });
2207            this.halt_action_dispatch
2208        })
2209    }
2210
2211    fn handle_action_dispatch_notification_effect(&mut self, action_id: TypeId) {
2212        self.action_dispatch_observations
2213            .clone()
2214            .emit((), self, |callback, this| {
2215                callback(action_id, this);
2216                true
2217            });
2218    }
2219
2220    fn handle_window_should_close_subscription_effect(
2221        &mut self,
2222        window_id: usize,
2223        mut callback: WindowShouldCloseSubscriptionCallback,
2224    ) {
2225        let mut app = self.upgrade();
2226        if let Some(window) = self.windows.get_mut(&window_id) {
2227            window
2228                .platform_window
2229                .on_should_close(Box::new(move || app.update(|cx| callback(cx))))
2230        }
2231    }
2232
2233    fn handle_window_moved(&mut self, window_id: usize) {
2234        self.update_window(window_id, |cx| {
2235            if let Some(display) = cx.window_display_uuid() {
2236                let bounds = cx.window_bounds();
2237                cx.window_bounds_observations
2238                    .clone()
2239                    .emit(window_id, cx, move |callback, this| {
2240                        callback(bounds, display, this);
2241                        true
2242                    });
2243            }
2244        });
2245    }
2246
2247    fn handle_active_labeled_tasks_changed_effect(&mut self) {
2248        self.active_labeled_task_observations
2249            .clone()
2250            .emit((), self, move |callback, this| {
2251                callback(this);
2252                true
2253            });
2254    }
2255
2256    pub fn focus(&mut self, window_id: usize, view_id: Option<usize>) {
2257        self.pending_effects
2258            .push_back(Effect::Focus { window_id, view_id });
2259    }
2260
2261    fn spawn_internal<F, Fut, T>(&mut self, task_name: Option<&'static str>, f: F) -> Task<T>
2262    where
2263        F: FnOnce(AsyncAppContext) -> Fut,
2264        Fut: 'static + Future<Output = T>,
2265        T: 'static,
2266    {
2267        let label_id = task_name.map(|task_name| {
2268            let id = post_inc(&mut self.next_labeled_task_id);
2269            self.active_labeled_tasks.insert(id, task_name);
2270            self.pending_effects
2271                .push_back(Effect::ActiveLabeledTasksChanged);
2272            id
2273        });
2274
2275        let future = f(self.to_async());
2276        let cx = self.to_async();
2277        self.foreground.spawn(async move {
2278            let result = future.await;
2279            let mut cx = cx.0.borrow_mut();
2280
2281            if let Some(completed_label_id) = label_id {
2282                cx.active_labeled_tasks.remove(&completed_label_id);
2283                cx.pending_effects
2284                    .push_back(Effect::ActiveLabeledTasksChanged);
2285            }
2286            cx.flush_effects();
2287            result
2288        })
2289    }
2290
2291    pub fn spawn_labeled<F, Fut, T>(&mut self, task_name: &'static str, f: F) -> Task<T>
2292    where
2293        F: FnOnce(AsyncAppContext) -> Fut,
2294        Fut: 'static + Future<Output = T>,
2295        T: 'static,
2296    {
2297        self.spawn_internal(Some(task_name), f)
2298    }
2299
2300    pub fn spawn<F, Fut, T>(&mut self, f: F) -> Task<T>
2301    where
2302        F: FnOnce(AsyncAppContext) -> Fut,
2303        Fut: 'static + Future<Output = T>,
2304        T: 'static,
2305    {
2306        self.spawn_internal(None, f)
2307    }
2308
2309    pub fn to_async(&self) -> AsyncAppContext {
2310        AsyncAppContext(self.weak_self.as_ref().unwrap().upgrade().unwrap())
2311    }
2312
2313    pub fn write_to_clipboard(&self, item: ClipboardItem) {
2314        self.platform.write_to_clipboard(item);
2315    }
2316
2317    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
2318        self.platform.read_from_clipboard()
2319    }
2320
2321    #[cfg(any(test, feature = "test-support"))]
2322    pub fn leak_detector(&self) -> Arc<Mutex<LeakDetector>> {
2323        self.ref_counts.lock().leak_detector.clone()
2324    }
2325}
2326
2327impl ReadModel for AppContext {
2328    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
2329        if let Some(model) = self.models.get(&handle.model_id) {
2330            model
2331                .as_any()
2332                .downcast_ref()
2333                .expect("downcast is type safe")
2334        } else {
2335            panic!("circular model reference");
2336        }
2337    }
2338}
2339
2340impl UpdateModel for AppContext {
2341    fn update_model<T: Entity, V>(
2342        &mut self,
2343        handle: &ModelHandle<T>,
2344        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
2345    ) -> V {
2346        if let Some(mut model) = self.models.remove(&handle.model_id) {
2347            self.update(|this| {
2348                let mut cx = ModelContext::new(this, handle.model_id);
2349                let result = update(
2350                    model
2351                        .as_any_mut()
2352                        .downcast_mut()
2353                        .expect("downcast is type safe"),
2354                    &mut cx,
2355                );
2356                this.models.insert(handle.model_id, model);
2357                result
2358            })
2359        } else {
2360            panic!("circular model update");
2361        }
2362    }
2363}
2364
2365impl UpgradeModelHandle for AppContext {
2366    fn upgrade_model_handle<T: Entity>(
2367        &self,
2368        handle: &WeakModelHandle<T>,
2369    ) -> Option<ModelHandle<T>> {
2370        if self.models.contains_key(&handle.model_id) {
2371            Some(ModelHandle::new(handle.model_id, &self.ref_counts))
2372        } else {
2373            None
2374        }
2375    }
2376
2377    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
2378        self.models.contains_key(&handle.model_id)
2379    }
2380
2381    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
2382        if self.models.contains_key(&handle.model_id) {
2383            Some(AnyModelHandle::new(
2384                handle.model_id,
2385                handle.model_type,
2386                self.ref_counts.clone(),
2387            ))
2388        } else {
2389            None
2390        }
2391    }
2392}
2393
2394impl UpgradeViewHandle for AppContext {
2395    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
2396        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
2397            Some(ViewHandle::new(
2398                handle.window_id,
2399                handle.view_id,
2400                &self.ref_counts,
2401            ))
2402        } else {
2403            None
2404        }
2405    }
2406
2407    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
2408        if self.ref_counts.lock().is_entity_alive(handle.view_id) {
2409            Some(AnyViewHandle::new(
2410                handle.window_id,
2411                handle.view_id,
2412                handle.view_type,
2413                self.ref_counts.clone(),
2414            ))
2415        } else {
2416            None
2417        }
2418    }
2419}
2420
2421impl ReadView for AppContext {
2422    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
2423        if let Some(view) = self.views.get(&(handle.window_id, handle.view_id)) {
2424            view.as_any().downcast_ref().expect("downcast is type safe")
2425        } else {
2426            panic!("circular view reference for type {}", type_name::<T>());
2427        }
2428    }
2429}
2430
2431impl UpdateView for AppContext {
2432    fn update_view<T, S>(
2433        &mut self,
2434        handle: &ViewHandle<T>,
2435        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
2436    ) -> S
2437    where
2438        T: View,
2439    {
2440        self.update_window(handle.window_id, |cx| cx.update_view(handle, update))
2441            .unwrap() // TODO: Is this unwrap safe?
2442    }
2443}
2444
2445#[derive(Debug)]
2446pub enum ParentId {
2447    View(usize),
2448    Root,
2449}
2450
2451#[derive(Default, Clone)]
2452pub struct WindowInvalidation {
2453    pub updated: HashSet<usize>,
2454    pub removed: Vec<usize>,
2455}
2456
2457pub enum Effect {
2458    Subscription {
2459        entity_id: usize,
2460        subscription_id: usize,
2461        callback: SubscriptionCallback,
2462    },
2463    Event {
2464        entity_id: usize,
2465        payload: Box<dyn Any>,
2466    },
2467    GlobalSubscription {
2468        type_id: TypeId,
2469        subscription_id: usize,
2470        callback: GlobalSubscriptionCallback,
2471    },
2472    GlobalEvent {
2473        payload: Box<dyn Any>,
2474    },
2475    Observation {
2476        entity_id: usize,
2477        subscription_id: usize,
2478        callback: ObservationCallback,
2479    },
2480    ModelNotification {
2481        model_id: usize,
2482    },
2483    ViewNotification {
2484        window_id: usize,
2485        view_id: usize,
2486    },
2487    Deferred {
2488        callback: Box<dyn FnOnce(&mut AppContext)>,
2489        after_window_update: bool,
2490    },
2491    GlobalNotification {
2492        type_id: TypeId,
2493    },
2494    ModelRelease {
2495        model_id: usize,
2496        model: Box<dyn AnyModel>,
2497    },
2498    ViewRelease {
2499        view_id: usize,
2500        view: Box<dyn AnyView>,
2501    },
2502    Focus {
2503        window_id: usize,
2504        view_id: Option<usize>,
2505    },
2506    FocusObservation {
2507        view_id: usize,
2508        subscription_id: usize,
2509        callback: FocusObservationCallback,
2510    },
2511    ResizeWindow {
2512        window_id: usize,
2513    },
2514    MoveWindow {
2515        window_id: usize,
2516    },
2517    ActivateWindow {
2518        window_id: usize,
2519        is_active: bool,
2520    },
2521    WindowActivationObservation {
2522        window_id: usize,
2523        subscription_id: usize,
2524        callback: WindowActivationCallback,
2525    },
2526    FullscreenWindow {
2527        window_id: usize,
2528        is_fullscreen: bool,
2529    },
2530    WindowFullscreenObservation {
2531        window_id: usize,
2532        subscription_id: usize,
2533        callback: WindowFullscreenCallback,
2534    },
2535    WindowBoundsObservation {
2536        window_id: usize,
2537        subscription_id: usize,
2538        callback: WindowBoundsCallback,
2539    },
2540    Keystroke {
2541        window_id: usize,
2542        keystroke: Keystroke,
2543        handled_by: Option<Box<dyn Action>>,
2544        result: MatchResult,
2545    },
2546    RefreshWindows,
2547    DispatchActionFrom {
2548        window_id: usize,
2549        view_id: usize,
2550        action: Box<dyn Action>,
2551    },
2552    ActionDispatchNotification {
2553        action_id: TypeId,
2554    },
2555    WindowShouldCloseSubscription {
2556        window_id: usize,
2557        callback: WindowShouldCloseSubscriptionCallback,
2558    },
2559    ActiveLabeledTasksChanged,
2560    ActiveLabeledTasksObservation {
2561        subscription_id: usize,
2562        callback: ActiveLabeledTasksCallback,
2563    },
2564}
2565
2566impl Debug for Effect {
2567    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2568        match self {
2569            Effect::Subscription {
2570                entity_id,
2571                subscription_id,
2572                ..
2573            } => f
2574                .debug_struct("Effect::Subscribe")
2575                .field("entity_id", entity_id)
2576                .field("subscription_id", subscription_id)
2577                .finish(),
2578            Effect::Event { entity_id, .. } => f
2579                .debug_struct("Effect::Event")
2580                .field("entity_id", entity_id)
2581                .finish(),
2582            Effect::GlobalSubscription {
2583                type_id,
2584                subscription_id,
2585                ..
2586            } => f
2587                .debug_struct("Effect::Subscribe")
2588                .field("type_id", type_id)
2589                .field("subscription_id", subscription_id)
2590                .finish(),
2591            Effect::GlobalEvent { payload, .. } => f
2592                .debug_struct("Effect::GlobalEvent")
2593                .field("type_id", &(&*payload).type_id())
2594                .finish(),
2595            Effect::Observation {
2596                entity_id,
2597                subscription_id,
2598                ..
2599            } => f
2600                .debug_struct("Effect::Observation")
2601                .field("entity_id", entity_id)
2602                .field("subscription_id", subscription_id)
2603                .finish(),
2604            Effect::ModelNotification { model_id } => f
2605                .debug_struct("Effect::ModelNotification")
2606                .field("model_id", model_id)
2607                .finish(),
2608            Effect::ViewNotification { window_id, view_id } => f
2609                .debug_struct("Effect::ViewNotification")
2610                .field("window_id", window_id)
2611                .field("view_id", view_id)
2612                .finish(),
2613            Effect::GlobalNotification { type_id } => f
2614                .debug_struct("Effect::GlobalNotification")
2615                .field("type_id", type_id)
2616                .finish(),
2617            Effect::Deferred { .. } => f.debug_struct("Effect::Deferred").finish(),
2618            Effect::ModelRelease { model_id, .. } => f
2619                .debug_struct("Effect::ModelRelease")
2620                .field("model_id", model_id)
2621                .finish(),
2622            Effect::ViewRelease { view_id, .. } => f
2623                .debug_struct("Effect::ViewRelease")
2624                .field("view_id", view_id)
2625                .finish(),
2626            Effect::Focus { window_id, view_id } => f
2627                .debug_struct("Effect::Focus")
2628                .field("window_id", window_id)
2629                .field("view_id", view_id)
2630                .finish(),
2631            Effect::FocusObservation {
2632                view_id,
2633                subscription_id,
2634                ..
2635            } => f
2636                .debug_struct("Effect::FocusObservation")
2637                .field("view_id", view_id)
2638                .field("subscription_id", subscription_id)
2639                .finish(),
2640            Effect::DispatchActionFrom {
2641                window_id, view_id, ..
2642            } => f
2643                .debug_struct("Effect::DispatchActionFrom")
2644                .field("window_id", window_id)
2645                .field("view_id", view_id)
2646                .finish(),
2647            Effect::ActionDispatchNotification { action_id, .. } => f
2648                .debug_struct("Effect::ActionDispatchNotification")
2649                .field("action_id", action_id)
2650                .finish(),
2651            Effect::ResizeWindow { window_id } => f
2652                .debug_struct("Effect::RefreshWindow")
2653                .field("window_id", window_id)
2654                .finish(),
2655            Effect::MoveWindow { window_id } => f
2656                .debug_struct("Effect::MoveWindow")
2657                .field("window_id", window_id)
2658                .finish(),
2659            Effect::WindowActivationObservation {
2660                window_id,
2661                subscription_id,
2662                ..
2663            } => f
2664                .debug_struct("Effect::WindowActivationObservation")
2665                .field("window_id", window_id)
2666                .field("subscription_id", subscription_id)
2667                .finish(),
2668            Effect::ActivateWindow {
2669                window_id,
2670                is_active,
2671            } => f
2672                .debug_struct("Effect::ActivateWindow")
2673                .field("window_id", window_id)
2674                .field("is_active", is_active)
2675                .finish(),
2676            Effect::FullscreenWindow {
2677                window_id,
2678                is_fullscreen,
2679            } => f
2680                .debug_struct("Effect::FullscreenWindow")
2681                .field("window_id", window_id)
2682                .field("is_fullscreen", is_fullscreen)
2683                .finish(),
2684            Effect::WindowFullscreenObservation {
2685                window_id,
2686                subscription_id,
2687                callback: _,
2688            } => f
2689                .debug_struct("Effect::WindowFullscreenObservation")
2690                .field("window_id", window_id)
2691                .field("subscription_id", subscription_id)
2692                .finish(),
2693
2694            Effect::WindowBoundsObservation {
2695                window_id,
2696                subscription_id,
2697                callback: _,
2698            } => f
2699                .debug_struct("Effect::WindowBoundsObservation")
2700                .field("window_id", window_id)
2701                .field("subscription_id", subscription_id)
2702                .finish(),
2703            Effect::RefreshWindows => f.debug_struct("Effect::FullViewRefresh").finish(),
2704            Effect::WindowShouldCloseSubscription { window_id, .. } => f
2705                .debug_struct("Effect::WindowShouldCloseSubscription")
2706                .field("window_id", window_id)
2707                .finish(),
2708            Effect::Keystroke {
2709                window_id,
2710                keystroke,
2711                handled_by,
2712                result,
2713            } => f
2714                .debug_struct("Effect::Keystroke")
2715                .field("window_id", window_id)
2716                .field("keystroke", keystroke)
2717                .field(
2718                    "keystroke",
2719                    &handled_by.as_ref().map(|handled_by| handled_by.name()),
2720                )
2721                .field("result", result)
2722                .finish(),
2723            Effect::ActiveLabeledTasksChanged => {
2724                f.debug_struct("Effect::ActiveLabeledTasksChanged").finish()
2725            }
2726            Effect::ActiveLabeledTasksObservation {
2727                subscription_id,
2728                callback: _,
2729            } => f
2730                .debug_struct("Effect::ActiveLabeledTasksObservation")
2731                .field("subscription_id", subscription_id)
2732                .finish(),
2733        }
2734    }
2735}
2736
2737pub trait AnyModel {
2738    fn as_any(&self) -> &dyn Any;
2739    fn as_any_mut(&mut self) -> &mut dyn Any;
2740    fn release(&mut self, cx: &mut AppContext);
2741    fn app_will_quit(
2742        &mut self,
2743        cx: &mut AppContext,
2744    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2745}
2746
2747impl<T> AnyModel for T
2748where
2749    T: Entity,
2750{
2751    fn as_any(&self) -> &dyn Any {
2752        self
2753    }
2754
2755    fn as_any_mut(&mut self) -> &mut dyn Any {
2756        self
2757    }
2758
2759    fn release(&mut self, cx: &mut AppContext) {
2760        self.release(cx);
2761    }
2762
2763    fn app_will_quit(
2764        &mut self,
2765        cx: &mut AppContext,
2766    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2767        self.app_will_quit(cx)
2768    }
2769}
2770
2771pub trait AnyView {
2772    fn as_any(&self) -> &dyn Any;
2773    fn as_any_mut(&mut self) -> &mut dyn Any;
2774    fn release(&mut self, cx: &mut AppContext);
2775    fn app_will_quit(
2776        &mut self,
2777        cx: &mut AppContext,
2778    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>>;
2779    fn ui_name(&self) -> &'static str;
2780    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement>;
2781    fn focus_in<'a, 'b>(
2782        &mut self,
2783        focused_id: usize,
2784        cx: &mut WindowContext<'a, 'b>,
2785        view_id: usize,
2786    );
2787    fn focus_out(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize);
2788    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2789    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool;
2790    fn modifiers_changed(
2791        &mut self,
2792        event: &ModifiersChangedEvent,
2793        cx: &mut WindowContext,
2794        view_id: usize,
2795    ) -> bool;
2796    fn keymap_context(&self, cx: &AppContext) -> KeymapContext;
2797    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value;
2798
2799    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String>;
2800    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2801    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>>;
2802    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize);
2803    fn replace_text_in_range(
2804        &mut self,
2805        range: Option<Range<usize>>,
2806        text: &str,
2807        cx: &mut WindowContext,
2808        view_id: usize,
2809    );
2810    fn replace_and_mark_text_in_range(
2811        &mut self,
2812        range: Option<Range<usize>>,
2813        new_text: &str,
2814        new_selected_range: Option<Range<usize>>,
2815        cx: &mut WindowContext,
2816        view_id: usize,
2817    );
2818    fn any_handle(&self, window_id: usize, view_id: usize, cx: &AppContext) -> AnyViewHandle {
2819        AnyViewHandle::new(
2820            window_id,
2821            view_id,
2822            self.as_any().type_id(),
2823            cx.ref_counts.clone(),
2824        )
2825    }
2826}
2827
2828impl<V> AnyView for V
2829where
2830    V: View,
2831{
2832    fn as_any(&self) -> &dyn Any {
2833        self
2834    }
2835
2836    fn as_any_mut(&mut self) -> &mut dyn Any {
2837        self
2838    }
2839
2840    fn release(&mut self, cx: &mut AppContext) {
2841        self.release(cx);
2842    }
2843
2844    fn app_will_quit(
2845        &mut self,
2846        cx: &mut AppContext,
2847    ) -> Option<Pin<Box<dyn 'static + Future<Output = ()>>>> {
2848        self.app_will_quit(cx)
2849    }
2850
2851    fn ui_name(&self) -> &'static str {
2852        V::ui_name()
2853    }
2854
2855    fn render(&mut self, cx: &mut WindowContext, view_id: usize) -> Box<dyn AnyRootElement> {
2856        let mut view_context = ViewContext::mutable(cx, view_id);
2857        let element = V::render(self, &mut view_context);
2858        let view = WeakViewHandle::new(cx.window_id, view_id);
2859        Box::new(RootElement::new(element, view))
2860    }
2861
2862    fn focus_in(&mut self, focused_id: usize, cx: &mut WindowContext, view_id: usize) {
2863        let mut cx = ViewContext::mutable(cx, view_id);
2864        let focused_view_handle: AnyViewHandle = if view_id == focused_id {
2865            cx.handle().into_any()
2866        } else {
2867            let focused_type = cx
2868                .views
2869                .get(&(cx.window_id, focused_id))
2870                .unwrap()
2871                .as_any()
2872                .type_id();
2873            AnyViewHandle::new(
2874                cx.window_id,
2875                focused_id,
2876                focused_type,
2877                cx.ref_counts.clone(),
2878            )
2879        };
2880        View::focus_in(self, focused_view_handle, &mut cx);
2881    }
2882
2883    fn focus_out(&mut self, blurred_id: usize, cx: &mut WindowContext, view_id: usize) {
2884        let mut cx = ViewContext::mutable(cx, view_id);
2885        let blurred_view_handle: AnyViewHandle = if view_id == blurred_id {
2886            cx.handle().into_any()
2887        } else {
2888            let blurred_type = cx
2889                .views
2890                .get(&(cx.window_id, blurred_id))
2891                .unwrap()
2892                .as_any()
2893                .type_id();
2894            AnyViewHandle::new(
2895                cx.window_id,
2896                blurred_id,
2897                blurred_type,
2898                cx.ref_counts.clone(),
2899            )
2900        };
2901        View::focus_out(self, blurred_view_handle, &mut cx);
2902    }
2903
2904    fn key_down(&mut self, event: &KeyDownEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2905        let mut cx = ViewContext::mutable(cx, view_id);
2906        View::key_down(self, event, &mut cx)
2907    }
2908
2909    fn key_up(&mut self, event: &KeyUpEvent, cx: &mut WindowContext, view_id: usize) -> bool {
2910        let mut cx = ViewContext::mutable(cx, view_id);
2911        View::key_up(self, event, &mut cx)
2912    }
2913
2914    fn modifiers_changed(
2915        &mut self,
2916        event: &ModifiersChangedEvent,
2917        cx: &mut WindowContext,
2918        view_id: usize,
2919    ) -> bool {
2920        let mut cx = ViewContext::mutable(cx, view_id);
2921        View::modifiers_changed(self, event, &mut cx)
2922    }
2923
2924    fn keymap_context(&self, cx: &AppContext) -> KeymapContext {
2925        View::keymap_context(self, cx)
2926    }
2927
2928    fn debug_json(&self, cx: &WindowContext) -> serde_json::Value {
2929        View::debug_json(self, cx)
2930    }
2931
2932    fn text_for_range(&self, range: Range<usize>, cx: &WindowContext) -> Option<String> {
2933        View::text_for_range(self, range, cx)
2934    }
2935
2936    fn selected_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2937        View::selected_text_range(self, cx)
2938    }
2939
2940    fn marked_text_range(&self, cx: &WindowContext) -> Option<Range<usize>> {
2941        View::marked_text_range(self, cx)
2942    }
2943
2944    fn unmark_text(&mut self, cx: &mut WindowContext, view_id: usize) {
2945        let mut cx = ViewContext::mutable(cx, view_id);
2946        View::unmark_text(self, &mut cx)
2947    }
2948
2949    fn replace_text_in_range(
2950        &mut self,
2951        range: Option<Range<usize>>,
2952        text: &str,
2953        cx: &mut WindowContext,
2954        view_id: usize,
2955    ) {
2956        let mut cx = ViewContext::mutable(cx, view_id);
2957        View::replace_text_in_range(self, range, text, &mut cx)
2958    }
2959
2960    fn replace_and_mark_text_in_range(
2961        &mut self,
2962        range: Option<Range<usize>>,
2963        new_text: &str,
2964        new_selected_range: Option<Range<usize>>,
2965        cx: &mut WindowContext,
2966        view_id: usize,
2967    ) {
2968        let mut cx = ViewContext::mutable(cx, view_id);
2969        View::replace_and_mark_text_in_range(self, range, new_text, new_selected_range, &mut cx)
2970    }
2971}
2972
2973pub struct ModelContext<'a, T: ?Sized> {
2974    app: &'a mut AppContext,
2975    model_id: usize,
2976    model_type: PhantomData<T>,
2977    halt_stream: bool,
2978}
2979
2980impl<'a, T: Entity> ModelContext<'a, T> {
2981    fn new(app: &'a mut AppContext, model_id: usize) -> Self {
2982        Self {
2983            app,
2984            model_id,
2985            model_type: PhantomData,
2986            halt_stream: false,
2987        }
2988    }
2989
2990    pub fn background(&self) -> &Arc<executor::Background> {
2991        &self.app.background
2992    }
2993
2994    pub fn halt_stream(&mut self) {
2995        self.halt_stream = true;
2996    }
2997
2998    pub fn model_id(&self) -> usize {
2999        self.model_id
3000    }
3001
3002    pub fn add_model<S, F>(&mut self, build_model: F) -> ModelHandle<S>
3003    where
3004        S: Entity,
3005        F: FnOnce(&mut ModelContext<S>) -> S,
3006    {
3007        self.app.add_model(build_model)
3008    }
3009
3010    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut T, &mut ModelContext<T>)) {
3011        let handle = self.handle();
3012        self.app.defer(move |cx| {
3013            handle.update(cx, |model, cx| {
3014                callback(model, cx);
3015            })
3016        })
3017    }
3018
3019    pub fn emit(&mut self, payload: T::Event) {
3020        self.app.pending_effects.push_back(Effect::Event {
3021            entity_id: self.model_id,
3022            payload: Box::new(payload),
3023        });
3024    }
3025
3026    pub fn notify(&mut self) {
3027        self.app.notify_model(self.model_id);
3028    }
3029
3030    pub fn subscribe<S: Entity, F>(
3031        &mut self,
3032        handle: &ModelHandle<S>,
3033        mut callback: F,
3034    ) -> Subscription
3035    where
3036        S::Event: 'static,
3037        F: 'static + FnMut(&mut T, ModelHandle<S>, &S::Event, &mut ModelContext<T>),
3038    {
3039        let subscriber = self.weak_handle();
3040        self.app
3041            .subscribe_internal(handle, move |emitter, event, cx| {
3042                if let Some(subscriber) = subscriber.upgrade(cx) {
3043                    subscriber.update(cx, |subscriber, cx| {
3044                        callback(subscriber, emitter, event, cx);
3045                    });
3046                    true
3047                } else {
3048                    false
3049                }
3050            })
3051    }
3052
3053    pub fn observe<S, F>(&mut self, handle: &ModelHandle<S>, mut callback: F) -> Subscription
3054    where
3055        S: Entity,
3056        F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
3057    {
3058        let observer = self.weak_handle();
3059        self.app.observe_internal(handle, move |observed, cx| {
3060            if let Some(observer) = observer.upgrade(cx) {
3061                observer.update(cx, |observer, cx| {
3062                    callback(observer, observed, cx);
3063                });
3064                true
3065            } else {
3066                false
3067            }
3068        })
3069    }
3070
3071    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
3072    where
3073        G: Any,
3074        F: 'static + FnMut(&mut T, &mut ModelContext<T>),
3075    {
3076        let observer = self.weak_handle();
3077        self.app.observe_global::<G, _>(move |cx| {
3078            if let Some(observer) = observer.upgrade(cx) {
3079                observer.update(cx, |observer, cx| callback(observer, cx));
3080            }
3081        })
3082    }
3083
3084    pub fn observe_release<S, F>(
3085        &mut self,
3086        handle: &ModelHandle<S>,
3087        mut callback: F,
3088    ) -> Subscription
3089    where
3090        S: Entity,
3091        F: 'static + FnMut(&mut T, &S, &mut ModelContext<T>),
3092    {
3093        let observer = self.weak_handle();
3094        self.app.observe_release(handle, move |released, cx| {
3095            if let Some(observer) = observer.upgrade(cx) {
3096                observer.update(cx, |observer, cx| {
3097                    callback(observer, released, cx);
3098                });
3099            }
3100        })
3101    }
3102
3103    pub fn handle(&self) -> ModelHandle<T> {
3104        ModelHandle::new(self.model_id, &self.app.ref_counts)
3105    }
3106
3107    pub fn weak_handle(&self) -> WeakModelHandle<T> {
3108        WeakModelHandle::new(self.model_id)
3109    }
3110
3111    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
3112    where
3113        F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
3114        Fut: 'static + Future<Output = S>,
3115        S: 'static,
3116    {
3117        let handle = self.handle();
3118        self.app.spawn(|cx| f(handle, cx))
3119    }
3120
3121    pub fn spawn_weak<F, Fut, S>(&mut self, f: F) -> Task<S>
3122    where
3123        F: FnOnce(WeakModelHandle<T>, AsyncAppContext) -> Fut,
3124        Fut: 'static + Future<Output = S>,
3125        S: 'static,
3126    {
3127        let handle = self.weak_handle();
3128        self.app.spawn(|cx| f(handle, cx))
3129    }
3130}
3131
3132impl<M> AsRef<AppContext> for ModelContext<'_, M> {
3133    fn as_ref(&self) -> &AppContext {
3134        &self.app
3135    }
3136}
3137
3138impl<M> AsMut<AppContext> for ModelContext<'_, M> {
3139    fn as_mut(&mut self) -> &mut AppContext {
3140        self.app
3141    }
3142}
3143
3144impl<M> ReadModel for ModelContext<'_, M> {
3145    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
3146        self.app.read_model(handle)
3147    }
3148}
3149
3150impl<M> UpdateModel for ModelContext<'_, M> {
3151    fn update_model<T: Entity, V>(
3152        &mut self,
3153        handle: &ModelHandle<T>,
3154        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
3155    ) -> V {
3156        self.app.update_model(handle, update)
3157    }
3158}
3159
3160impl<M> UpgradeModelHandle for ModelContext<'_, M> {
3161    fn upgrade_model_handle<T: Entity>(
3162        &self,
3163        handle: &WeakModelHandle<T>,
3164    ) -> Option<ModelHandle<T>> {
3165        self.app.upgrade_model_handle(handle)
3166    }
3167
3168    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
3169        self.app.model_handle_is_upgradable(handle)
3170    }
3171
3172    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
3173        self.app.upgrade_any_model_handle(handle)
3174    }
3175}
3176
3177impl<M> Deref for ModelContext<'_, M> {
3178    type Target = AppContext;
3179
3180    fn deref(&self) -> &Self::Target {
3181        self.app
3182    }
3183}
3184
3185impl<M> DerefMut for ModelContext<'_, M> {
3186    fn deref_mut(&mut self) -> &mut Self::Target {
3187        &mut self.app
3188    }
3189}
3190
3191pub struct ViewContext<'a, 'b, 'c, T: ?Sized> {
3192    window_context: Reference<'c, WindowContext<'a, 'b>>,
3193    view_id: usize,
3194    view_type: PhantomData<T>,
3195}
3196
3197impl<'a, 'b, 'c, T: View> Deref for ViewContext<'a, 'b, 'c, T> {
3198    type Target = WindowContext<'a, 'b>;
3199
3200    fn deref(&self) -> &Self::Target {
3201        &self.window_context
3202    }
3203}
3204
3205impl<T: View> DerefMut for ViewContext<'_, '_, '_, T> {
3206    fn deref_mut(&mut self) -> &mut Self::Target {
3207        &mut self.window_context
3208    }
3209}
3210
3211impl<'a, 'b, 'c, V: View> ViewContext<'a, 'b, 'c, V> {
3212    pub(crate) fn mutable(window_context: &'c mut WindowContext<'a, 'b>, view_id: usize) -> Self {
3213        Self {
3214            window_context: Reference::Mutable(window_context),
3215            view_id,
3216            view_type: PhantomData,
3217        }
3218    }
3219
3220    pub(crate) fn immutable(window_context: &'c WindowContext<'a, 'b>, view_id: usize) -> Self {
3221        Self {
3222            window_context: Reference::Immutable(window_context),
3223            view_id,
3224            view_type: PhantomData,
3225        }
3226    }
3227
3228    pub fn handle(&self) -> ViewHandle<V> {
3229        ViewHandle::new(
3230            self.window_id,
3231            self.view_id,
3232            &self.window_context.ref_counts,
3233        )
3234    }
3235
3236    pub fn weak_handle(&self) -> WeakViewHandle<V> {
3237        WeakViewHandle::new(self.window_id, self.view_id)
3238    }
3239
3240    pub fn parent(&self) -> Option<usize> {
3241        self.window_context.parent(self.window_id, self.view_id)
3242    }
3243
3244    pub fn window_id(&self) -> usize {
3245        self.window_id
3246    }
3247
3248    pub fn view_id(&self) -> usize {
3249        self.view_id
3250    }
3251
3252    pub fn foreground(&self) -> &Rc<executor::Foreground> {
3253        self.window_context.foreground()
3254    }
3255
3256    pub fn background_executor(&self) -> &Arc<executor::Background> {
3257        &self.window_context.background
3258    }
3259
3260    pub fn platform(&self) -> &Arc<dyn Platform> {
3261        self.window_context.platform()
3262    }
3263
3264    pub fn prompt_for_paths(
3265        &self,
3266        options: PathPromptOptions,
3267    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
3268        self.window_context.prompt_for_paths(options)
3269    }
3270
3271    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
3272        self.window_context.prompt_for_new_path(directory)
3273    }
3274
3275    pub fn reveal_path(&self, path: &Path) {
3276        self.window_context.reveal_path(path)
3277    }
3278
3279    pub fn focus(&mut self, handle: &AnyViewHandle) {
3280        self.window_context
3281            .focus(handle.window_id, Some(handle.view_id));
3282    }
3283
3284    pub fn focus_self(&mut self) {
3285        let window_id = self.window_id;
3286        let view_id = self.view_id;
3287        self.window_context.focus(window_id, Some(view_id));
3288    }
3289
3290    pub fn is_self_focused(&self) -> bool {
3291        self.window.focused_view_id == Some(self.view_id)
3292    }
3293
3294    pub fn is_parent_view_focused(&self) -> bool {
3295        if let Some(parent_view_id) = self.ancestors(self.window_id, self.view_id).next().clone() {
3296            self.focused_view_id() == Some(parent_view_id)
3297        } else {
3298            false
3299        }
3300    }
3301
3302    pub fn focus_parent_view(&mut self) {
3303        let next = self.ancestors(self.window_id, self.view_id).next().clone();
3304        if let Some(parent_view_id) = next {
3305            let window_id = self.window_id;
3306            self.window_context.focus(window_id, Some(parent_view_id));
3307        }
3308    }
3309
3310    pub fn is_child(&self, view: impl Into<AnyViewHandle>) -> bool {
3311        let view = view.into();
3312        if self.window_id != view.window_id {
3313            return false;
3314        }
3315        self.ancestors(view.window_id, view.view_id)
3316            .skip(1) // Skip self id
3317            .any(|parent| parent == self.view_id)
3318    }
3319
3320    pub fn blur(&mut self) {
3321        let window_id = self.window_id;
3322        self.window_context.focus(window_id, None);
3323    }
3324
3325    pub fn on_window_should_close<F>(&mut self, mut callback: F)
3326    where
3327        F: 'static + FnMut(&mut V, &mut ViewContext<V>) -> bool,
3328    {
3329        let window_id = self.window_id();
3330        let view = self.weak_handle();
3331        self.pending_effects
3332            .push_back(Effect::WindowShouldCloseSubscription {
3333                window_id,
3334                callback: Box::new(move |cx| {
3335                    if let Some(view) = view.upgrade(cx) {
3336                        view.update(cx, |view, cx| callback(view, cx))
3337                    } else {
3338                        true
3339                    }
3340                }),
3341            });
3342    }
3343
3344    pub fn add_view<S, F>(&mut self, build_view: F) -> ViewHandle<S>
3345    where
3346        S: View,
3347        F: FnOnce(&mut ViewContext<S>) -> S,
3348    {
3349        self.window_context
3350            .build_and_insert_view(ParentId::View(self.view_id), |cx| Some(build_view(cx)))
3351            .unwrap()
3352    }
3353
3354    pub fn add_option_view<S, F>(&mut self, build_view: F) -> Option<ViewHandle<S>>
3355    where
3356        S: View,
3357        F: FnOnce(&mut ViewContext<S>) -> Option<S>,
3358    {
3359        self.window_context
3360            .build_and_insert_view(ParentId::View(self.view_id), build_view)
3361    }
3362
3363    pub fn reparent(&mut self, view_handle: &AnyViewHandle) {
3364        if self.window_id != view_handle.window_id {
3365            panic!("Can't reparent view to a view from a different window");
3366        }
3367        self.parents
3368            .remove(&(view_handle.window_id, view_handle.view_id));
3369        let new_parent_id = self.view_id;
3370        self.parents.insert(
3371            (view_handle.window_id, view_handle.view_id),
3372            ParentId::View(new_parent_id),
3373        );
3374    }
3375
3376    pub fn subscribe<E, H, F>(&mut self, handle: &H, mut callback: F) -> Subscription
3377    where
3378        E: Entity,
3379        E::Event: 'static,
3380        H: Handle<E>,
3381        F: 'static + FnMut(&mut V, H, &E::Event, &mut ViewContext<V>),
3382    {
3383        let subscriber = self.weak_handle();
3384        self.window_context
3385            .subscribe_internal(handle, move |emitter, event, cx| {
3386                if let Some(subscriber) = subscriber.upgrade(cx) {
3387                    subscriber.update(cx, |subscriber, cx| {
3388                        callback(subscriber, emitter, event, cx);
3389                    });
3390                    true
3391                } else {
3392                    false
3393                }
3394            })
3395    }
3396
3397    pub fn observe<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3398    where
3399        E: Entity,
3400        H: Handle<E>,
3401        F: 'static + FnMut(&mut V, H, &mut ViewContext<V>),
3402    {
3403        let observer = self.weak_handle();
3404        self.window_context
3405            .observe_internal(handle, move |observed, cx| {
3406                if let Some(observer) = observer.upgrade(cx) {
3407                    observer.update(cx, |observer, cx| {
3408                        callback(observer, observed, cx);
3409                    });
3410                    true
3411                } else {
3412                    false
3413                }
3414            })
3415    }
3416
3417    pub fn observe_global<G, F>(&mut self, mut callback: F) -> Subscription
3418    where
3419        G: Any,
3420        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
3421    {
3422        let observer = self.weak_handle();
3423        self.window_context.observe_global::<G, _>(move |cx| {
3424            if let Some(observer) = observer.upgrade(cx) {
3425                observer.update(cx, |observer, cx| callback(observer, cx));
3426            }
3427        })
3428    }
3429
3430    pub fn observe_focus<F, W>(&mut self, handle: &ViewHandle<W>, mut callback: F) -> Subscription
3431    where
3432        F: 'static + FnMut(&mut V, ViewHandle<W>, bool, &mut ViewContext<V>),
3433        W: View,
3434    {
3435        let observer = self.weak_handle();
3436        self.window_context
3437            .observe_focus(handle, move |observed, focused, cx| {
3438                if let Some(observer) = observer.upgrade(cx) {
3439                    observer.update(cx, |observer, cx| {
3440                        callback(observer, observed, focused, cx);
3441                    });
3442                    true
3443                } else {
3444                    false
3445                }
3446            })
3447    }
3448
3449    pub fn observe_release<E, F, H>(&mut self, handle: &H, mut callback: F) -> Subscription
3450    where
3451        E: Entity,
3452        H: Handle<E>,
3453        F: 'static + FnMut(&mut V, &E, &mut ViewContext<V>),
3454    {
3455        let observer = self.weak_handle();
3456        self.window_context
3457            .observe_release(handle, move |released, cx| {
3458                if let Some(observer) = observer.upgrade(cx) {
3459                    observer.update(cx, |observer, cx| {
3460                        callback(observer, released, cx);
3461                    });
3462                }
3463            })
3464    }
3465
3466    pub fn observe_actions<F>(&mut self, mut callback: F) -> Subscription
3467    where
3468        F: 'static + FnMut(&mut V, TypeId, &mut ViewContext<V>),
3469    {
3470        let observer = self.weak_handle();
3471        self.window_context.observe_actions(move |action_id, cx| {
3472            if let Some(observer) = observer.upgrade(cx) {
3473                observer.update(cx, |observer, cx| {
3474                    callback(observer, action_id, cx);
3475                });
3476            }
3477        })
3478    }
3479
3480    pub fn observe_window_activation<F>(&mut self, mut callback: F) -> Subscription
3481    where
3482        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3483    {
3484        let observer = self.weak_handle();
3485        let window_id = self.window_id;
3486        self.window_context
3487            .observe_window_activation(window_id, move |active, cx| {
3488                if let Some(observer) = observer.upgrade(cx) {
3489                    observer.update(cx, |observer, cx| {
3490                        callback(observer, active, cx);
3491                    });
3492                    true
3493                } else {
3494                    false
3495                }
3496            })
3497    }
3498
3499    pub fn observe_fullscreen<F>(&mut self, mut callback: F) -> Subscription
3500    where
3501        F: 'static + FnMut(&mut V, bool, &mut ViewContext<V>),
3502    {
3503        let observer = self.weak_handle();
3504        let window_id = self.window_id;
3505        self.window_context
3506            .observe_fullscreen(window_id, move |active, cx| {
3507                if let Some(observer) = observer.upgrade(cx) {
3508                    observer.update(cx, |observer, cx| {
3509                        callback(observer, active, cx);
3510                    });
3511                    true
3512                } else {
3513                    false
3514                }
3515            })
3516    }
3517
3518    pub fn observe_keystrokes<F>(&mut self, mut callback: F) -> Subscription
3519    where
3520        F: 'static
3521            + FnMut(
3522                &mut V,
3523                &Keystroke,
3524                Option<&Box<dyn Action>>,
3525                &MatchResult,
3526                &mut ViewContext<V>,
3527            ) -> bool,
3528    {
3529        let observer = self.weak_handle();
3530        let window_id = self.window_id;
3531        self.window_context.observe_keystrokes(
3532            window_id,
3533            move |keystroke, result, handled_by, cx| {
3534                if let Some(observer) = observer.upgrade(cx) {
3535                    observer.update(cx, |observer, cx| {
3536                        callback(observer, keystroke, handled_by, result, cx);
3537                    });
3538                    true
3539                } else {
3540                    false
3541                }
3542            },
3543        )
3544    }
3545
3546    pub fn observe_window_bounds<F>(&mut self, mut callback: F) -> Subscription
3547    where
3548        F: 'static + FnMut(&mut V, WindowBounds, Uuid, &mut ViewContext<V>),
3549    {
3550        let observer = self.weak_handle();
3551        let window_id = self.window_id;
3552        self.window_context
3553            .observe_window_bounds(window_id, move |bounds, display, cx| {
3554                if let Some(observer) = observer.upgrade(cx) {
3555                    observer.update(cx, |observer, cx| {
3556                        callback(observer, bounds, display, cx);
3557                    });
3558                    true
3559                } else {
3560                    false
3561                }
3562            })
3563    }
3564
3565    pub fn observe_active_labeled_tasks<F>(&mut self, mut callback: F) -> Subscription
3566    where
3567        F: 'static + FnMut(&mut V, &mut ViewContext<V>),
3568    {
3569        let observer = self.weak_handle();
3570        self.window_context.observe_active_labeled_tasks(move |cx| {
3571            if let Some(observer) = observer.upgrade(cx) {
3572                observer.update(cx, |observer, cx| {
3573                    callback(observer, cx);
3574                });
3575                true
3576            } else {
3577                false
3578            }
3579        })
3580    }
3581
3582    pub fn emit(&mut self, payload: V::Event) {
3583        self.window_context
3584            .pending_effects
3585            .push_back(Effect::Event {
3586                entity_id: self.view_id,
3587                payload: Box::new(payload),
3588            });
3589    }
3590
3591    pub fn notify(&mut self) {
3592        let window_id = self.window_id;
3593        let view_id = self.view_id;
3594        self.window_context.notify_view(window_id, view_id);
3595    }
3596
3597    pub fn dispatch_action(&mut self, action: impl Action) {
3598        let window_id = self.window_id;
3599        let view_id = self.view_id;
3600        self.window_context
3601            .dispatch_action_at(window_id, view_id, action)
3602    }
3603
3604    pub fn dispatch_any_action(&mut self, action: Box<dyn Action>) {
3605        let window_id = self.window_id;
3606        let view_id = self.view_id;
3607        self.window_context
3608            .dispatch_any_action_at(window_id, view_id, action)
3609    }
3610
3611    pub fn defer(&mut self, callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>)) {
3612        let handle = self.handle();
3613        self.window_context.defer(move |cx| {
3614            handle.update(cx, |view, cx| {
3615                callback(view, cx);
3616            })
3617        })
3618    }
3619
3620    pub fn after_window_update(
3621        &mut self,
3622        callback: impl 'static + FnOnce(&mut V, &mut ViewContext<V>),
3623    ) {
3624        let handle = self.handle();
3625        self.window_context.after_window_update(move |cx| {
3626            handle.update(cx, |view, cx| {
3627                callback(view, cx);
3628            })
3629        })
3630    }
3631
3632    pub fn propagate_action(&mut self) {
3633        self.window_context.halt_action_dispatch = false;
3634    }
3635
3636    pub fn spawn_labeled<F, Fut, S>(&mut self, task_label: &'static str, f: F) -> Task<S>
3637    where
3638        F: FnOnce(ViewHandle<V>, AsyncAppContext) -> Fut,
3639        Fut: 'static + Future<Output = S>,
3640        S: 'static,
3641    {
3642        let handle = self.handle();
3643        self.window_context
3644            .spawn_labeled(task_label, |cx| f(handle, cx))
3645    }
3646
3647    pub fn spawn<F, Fut, S>(&mut self, f: F) -> Task<S>
3648    where
3649        F: FnOnce(ViewHandle<V>, AsyncAppContext) -> Fut,
3650        Fut: 'static + Future<Output = S>,
3651        S: 'static,
3652    {
3653        let handle = self.handle();
3654        self.window_context.spawn(|cx| f(handle, cx))
3655    }
3656
3657    pub fn spawn_weak<F, Fut, S>(&mut self, f: F) -> Task<S>
3658    where
3659        F: FnOnce(WeakViewHandle<V>, AsyncAppContext) -> Fut,
3660        Fut: 'static + Future<Output = S>,
3661        S: 'static,
3662    {
3663        let handle = self.weak_handle();
3664        self.window_context.spawn(|cx| f(handle, cx))
3665    }
3666
3667    pub fn mouse_state<Tag: 'static>(&self, region_id: usize) -> MouseState {
3668        let region_id = MouseRegionId::new::<Tag>(self.view_id, region_id);
3669        MouseState {
3670            hovered: self.window.hovered_region_ids.contains(&region_id),
3671            clicked: self
3672                .window
3673                .clicked_region_ids
3674                .get(&region_id)
3675                .and_then(|_| self.window.clicked_button),
3676            accessed_hovered: false,
3677            accessed_clicked: false,
3678        }
3679    }
3680
3681    pub fn element_state<Tag: 'static, T: 'static>(
3682        &mut self,
3683        element_id: usize,
3684        initial: T,
3685    ) -> ElementStateHandle<T> {
3686        let id = ElementStateId {
3687            view_id: self.view_id(),
3688            element_id,
3689            tag: TypeId::of::<Tag>(),
3690        };
3691        self.element_states
3692            .entry(id)
3693            .or_insert_with(|| Box::new(initial));
3694        ElementStateHandle::new(id, self.frame_count, &self.ref_counts)
3695    }
3696
3697    pub fn default_element_state<Tag: 'static, T: 'static + Default>(
3698        &mut self,
3699        element_id: usize,
3700    ) -> ElementStateHandle<T> {
3701        self.element_state::<Tag, T>(element_id, T::default())
3702    }
3703}
3704
3705impl<V> UpgradeModelHandle for ViewContext<'_, '_, '_, V> {
3706    fn upgrade_model_handle<T: Entity>(
3707        &self,
3708        handle: &WeakModelHandle<T>,
3709    ) -> Option<ModelHandle<T>> {
3710        self.window_context.upgrade_model_handle(handle)
3711    }
3712
3713    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
3714        self.window_context.model_handle_is_upgradable(handle)
3715    }
3716
3717    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
3718        self.window_context.upgrade_any_model_handle(handle)
3719    }
3720}
3721
3722impl<V> UpgradeViewHandle for ViewContext<'_, '_, '_, V> {
3723    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
3724        self.window_context.upgrade_view_handle(handle)
3725    }
3726
3727    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
3728        self.window_context.upgrade_any_view_handle(handle)
3729    }
3730}
3731
3732impl<V: View> ReadModel for ViewContext<'_, '_, '_, V> {
3733    fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
3734        self.window_context.read_model(handle)
3735    }
3736}
3737
3738impl<V: View> UpdateModel for ViewContext<'_, '_, '_, V> {
3739    fn update_model<T: Entity, O>(
3740        &mut self,
3741        handle: &ModelHandle<T>,
3742        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
3743    ) -> O {
3744        self.window_context.update_model(handle, update)
3745    }
3746}
3747
3748impl<V: View> ReadView for ViewContext<'_, '_, '_, V> {
3749    fn read_view<T: View>(&self, handle: &ViewHandle<T>) -> &T {
3750        self.window_context.read_view(handle)
3751    }
3752}
3753
3754impl<V: View> UpdateView for ViewContext<'_, '_, '_, V> {
3755    fn update_view<T, S>(
3756        &mut self,
3757        handle: &ViewHandle<T>,
3758        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
3759    ) -> S
3760    where
3761        T: View,
3762    {
3763        self.window_context.update_view(handle, update)
3764    }
3765}
3766
3767pub struct EventContext<'a, 'b, 'c, 'd, V: View> {
3768    view_context: &'d mut ViewContext<'a, 'b, 'c, V>,
3769    pub(crate) handled: bool,
3770}
3771
3772impl<'a, 'b, 'c, 'd, V: View> EventContext<'a, 'b, 'c, 'd, V> {
3773    pub(crate) fn new(view_context: &'d mut ViewContext<'a, 'b, 'c, V>) -> Self {
3774        EventContext {
3775            view_context,
3776            handled: true,
3777        }
3778    }
3779
3780    pub fn propagate_event(&mut self) {
3781        self.handled = false;
3782    }
3783}
3784
3785impl<'a, 'b, 'c, 'd, V: View> Deref for EventContext<'a, 'b, 'c, 'd, V> {
3786    type Target = ViewContext<'a, 'b, 'c, V>;
3787
3788    fn deref(&self) -> &Self::Target {
3789        &self.view_context
3790    }
3791}
3792
3793impl<V: View> DerefMut for EventContext<'_, '_, '_, '_, V> {
3794    fn deref_mut(&mut self) -> &mut Self::Target {
3795        &mut self.view_context
3796    }
3797}
3798
3799impl<V: View> UpdateModel for EventContext<'_, '_, '_, '_, V> {
3800    fn update_model<T: Entity, O>(
3801        &mut self,
3802        handle: &ModelHandle<T>,
3803        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
3804    ) -> O {
3805        self.view_context.update_model(handle, update)
3806    }
3807}
3808
3809impl<V: View> ReadView for EventContext<'_, '_, '_, '_, V> {
3810    fn read_view<W: View>(&self, handle: &crate::ViewHandle<W>) -> &W {
3811        self.view_context.read_view(handle)
3812    }
3813}
3814
3815impl<V: View> UpdateView for EventContext<'_, '_, '_, '_, V> {
3816    fn update_view<T, S>(
3817        &mut self,
3818        handle: &ViewHandle<T>,
3819        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
3820    ) -> S
3821    where
3822        T: View,
3823    {
3824        self.view_context.update_view(handle, update)
3825    }
3826}
3827
3828impl<V: View> UpgradeModelHandle for EventContext<'_, '_, '_, '_, V> {
3829    fn upgrade_model_handle<T: Entity>(
3830        &self,
3831        handle: &WeakModelHandle<T>,
3832    ) -> Option<ModelHandle<T>> {
3833        self.view_context.upgrade_model_handle(handle)
3834    }
3835
3836    fn model_handle_is_upgradable<T: Entity>(&self, handle: &WeakModelHandle<T>) -> bool {
3837        self.view_context.model_handle_is_upgradable(handle)
3838    }
3839
3840    fn upgrade_any_model_handle(&self, handle: &AnyWeakModelHandle) -> Option<AnyModelHandle> {
3841        self.view_context.upgrade_any_model_handle(handle)
3842    }
3843}
3844
3845impl<V: View> UpgradeViewHandle for EventContext<'_, '_, '_, '_, V> {
3846    fn upgrade_view_handle<T: View>(&self, handle: &WeakViewHandle<T>) -> Option<ViewHandle<T>> {
3847        self.view_context.upgrade_view_handle(handle)
3848    }
3849
3850    fn upgrade_any_view_handle(&self, handle: &AnyWeakViewHandle) -> Option<AnyViewHandle> {
3851        self.view_context.upgrade_any_view_handle(handle)
3852    }
3853}
3854
3855pub(crate) enum Reference<'a, T> {
3856    Immutable(&'a T),
3857    Mutable(&'a mut T),
3858}
3859
3860impl<'a, T> Deref for Reference<'a, T> {
3861    type Target = T;
3862
3863    fn deref(&self) -> &Self::Target {
3864        match self {
3865            Reference::Immutable(target) => target,
3866            Reference::Mutable(target) => target,
3867        }
3868    }
3869}
3870
3871impl<'a, T> DerefMut for Reference<'a, T> {
3872    fn deref_mut(&mut self) -> &mut Self::Target {
3873        match self {
3874            Reference::Immutable(_) => {
3875                panic!("cannot mutably deref an immutable reference. this is a bug in GPUI.");
3876            }
3877            Reference::Mutable(target) => target,
3878        }
3879    }
3880}
3881
3882#[derive(Debug, Clone, Default)]
3883pub struct MouseState {
3884    pub(crate) hovered: bool,
3885    pub(crate) clicked: Option<MouseButton>,
3886    pub(crate) accessed_hovered: bool,
3887    pub(crate) accessed_clicked: bool,
3888}
3889
3890impl MouseState {
3891    pub fn hovered(&mut self) -> bool {
3892        self.accessed_hovered = true;
3893        self.hovered
3894    }
3895
3896    pub fn clicked(&mut self) -> Option<MouseButton> {
3897        self.accessed_clicked = true;
3898        self.clicked
3899    }
3900
3901    pub fn accessed_hovered(&self) -> bool {
3902        self.accessed_hovered
3903    }
3904
3905    pub fn accessed_clicked(&self) -> bool {
3906        self.accessed_clicked
3907    }
3908}
3909
3910pub trait Handle<T> {
3911    type Weak: 'static;
3912    fn id(&self) -> usize;
3913    fn location(&self) -> EntityLocation;
3914    fn downgrade(&self) -> Self::Weak;
3915    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
3916    where
3917        Self: Sized;
3918}
3919
3920pub trait WeakHandle {
3921    fn id(&self) -> usize;
3922}
3923
3924#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
3925pub enum EntityLocation {
3926    Model(usize),
3927    View(usize, usize),
3928}
3929
3930pub struct ModelHandle<T: Entity> {
3931    any_handle: AnyModelHandle,
3932    model_type: PhantomData<T>,
3933}
3934
3935impl<T: Entity> Deref for ModelHandle<T> {
3936    type Target = AnyModelHandle;
3937
3938    fn deref(&self) -> &Self::Target {
3939        &self.any_handle
3940    }
3941}
3942
3943impl<T: Entity> ModelHandle<T> {
3944    fn new(model_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
3945        Self {
3946            any_handle: AnyModelHandle::new(model_id, TypeId::of::<T>(), ref_counts.clone()),
3947            model_type: PhantomData,
3948        }
3949    }
3950
3951    pub fn downgrade(&self) -> WeakModelHandle<T> {
3952        WeakModelHandle::new(self.model_id)
3953    }
3954
3955    pub fn id(&self) -> usize {
3956        self.model_id
3957    }
3958
3959    pub fn read<'a, C: ReadModel>(&self, cx: &'a C) -> &'a T {
3960        cx.read_model(self)
3961    }
3962
3963    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
3964    where
3965        C: ReadModelWith,
3966        F: FnOnce(&T, &AppContext) -> S,
3967    {
3968        let mut read = Some(read);
3969        cx.read_model_with(self, &mut |model, cx| {
3970            let read = read.take().unwrap();
3971            read(model, cx)
3972        })
3973    }
3974
3975    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
3976    where
3977        C: UpdateModel,
3978        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
3979    {
3980        let mut update = Some(update);
3981        cx.update_model(self, &mut |model, cx| {
3982            let update = update.take().unwrap();
3983            update(model, cx)
3984        })
3985    }
3986}
3987
3988impl<T: Entity> Clone for ModelHandle<T> {
3989    fn clone(&self) -> Self {
3990        Self::new(self.model_id, &self.ref_counts)
3991    }
3992}
3993
3994impl<T: Entity> PartialEq for ModelHandle<T> {
3995    fn eq(&self, other: &Self) -> bool {
3996        self.model_id == other.model_id
3997    }
3998}
3999
4000impl<T: Entity> Eq for ModelHandle<T> {}
4001
4002impl<T: Entity> PartialEq<WeakModelHandle<T>> for ModelHandle<T> {
4003    fn eq(&self, other: &WeakModelHandle<T>) -> bool {
4004        self.model_id == other.model_id
4005    }
4006}
4007
4008impl<T: Entity> Hash for ModelHandle<T> {
4009    fn hash<H: Hasher>(&self, state: &mut H) {
4010        self.model_id.hash(state);
4011    }
4012}
4013
4014impl<T: Entity> std::borrow::Borrow<usize> for ModelHandle<T> {
4015    fn borrow(&self) -> &usize {
4016        &self.model_id
4017    }
4018}
4019
4020impl<T: Entity> Debug for ModelHandle<T> {
4021    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4022        f.debug_tuple(&format!("ModelHandle<{}>", type_name::<T>()))
4023            .field(&self.model_id)
4024            .finish()
4025    }
4026}
4027
4028unsafe impl<T: Entity> Send for ModelHandle<T> {}
4029unsafe impl<T: Entity> Sync for ModelHandle<T> {}
4030
4031impl<T: Entity> Handle<T> for ModelHandle<T> {
4032    type Weak = WeakModelHandle<T>;
4033
4034    fn id(&self) -> usize {
4035        self.model_id
4036    }
4037
4038    fn location(&self) -> EntityLocation {
4039        EntityLocation::Model(self.model_id)
4040    }
4041
4042    fn downgrade(&self) -> Self::Weak {
4043        self.downgrade()
4044    }
4045
4046    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
4047    where
4048        Self: Sized,
4049    {
4050        weak.upgrade(cx)
4051    }
4052}
4053
4054pub struct WeakModelHandle<T> {
4055    any_handle: AnyWeakModelHandle,
4056    model_type: PhantomData<T>,
4057}
4058
4059impl<T> WeakModelHandle<T> {
4060    pub fn into_any(self) -> AnyWeakModelHandle {
4061        self.any_handle
4062    }
4063}
4064
4065impl<T> Deref for WeakModelHandle<T> {
4066    type Target = AnyWeakModelHandle;
4067
4068    fn deref(&self) -> &Self::Target {
4069        &self.any_handle
4070    }
4071}
4072
4073impl<T> WeakHandle for WeakModelHandle<T> {
4074    fn id(&self) -> usize {
4075        self.model_id
4076    }
4077}
4078
4079unsafe impl<T> Send for WeakModelHandle<T> {}
4080unsafe impl<T> Sync for WeakModelHandle<T> {}
4081
4082impl<T: Entity> WeakModelHandle<T> {
4083    fn new(model_id: usize) -> Self {
4084        Self {
4085            any_handle: AnyWeakModelHandle {
4086                model_id,
4087                model_type: TypeId::of::<T>(),
4088            },
4089            model_type: PhantomData,
4090        }
4091    }
4092
4093    pub fn id(&self) -> usize {
4094        self.model_id
4095    }
4096
4097    pub fn is_upgradable(&self, cx: &impl UpgradeModelHandle) -> bool {
4098        cx.model_handle_is_upgradable(self)
4099    }
4100
4101    pub fn upgrade(&self, cx: &impl UpgradeModelHandle) -> Option<ModelHandle<T>> {
4102        cx.upgrade_model_handle(self)
4103    }
4104}
4105
4106impl<T> Hash for WeakModelHandle<T> {
4107    fn hash<H: Hasher>(&self, state: &mut H) {
4108        self.model_id.hash(state)
4109    }
4110}
4111
4112impl<T> PartialEq for WeakModelHandle<T> {
4113    fn eq(&self, other: &Self) -> bool {
4114        self.model_id == other.model_id
4115    }
4116}
4117
4118impl<T> Eq for WeakModelHandle<T> {}
4119
4120impl<T: Entity> PartialEq<ModelHandle<T>> for WeakModelHandle<T> {
4121    fn eq(&self, other: &ModelHandle<T>) -> bool {
4122        self.model_id == other.model_id
4123    }
4124}
4125
4126impl<T> Clone for WeakModelHandle<T> {
4127    fn clone(&self) -> Self {
4128        Self {
4129            any_handle: self.any_handle.clone(),
4130            model_type: PhantomData,
4131        }
4132    }
4133}
4134
4135impl<T> Copy for WeakModelHandle<T> {}
4136
4137#[repr(transparent)]
4138pub struct ViewHandle<T> {
4139    any_handle: AnyViewHandle,
4140    view_type: PhantomData<T>,
4141}
4142
4143impl<T> Deref for ViewHandle<T> {
4144    type Target = AnyViewHandle;
4145
4146    fn deref(&self) -> &Self::Target {
4147        &self.any_handle
4148    }
4149}
4150
4151impl<T: View> ViewHandle<T> {
4152    fn new(window_id: usize, view_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
4153        Self {
4154            any_handle: AnyViewHandle::new(
4155                window_id,
4156                view_id,
4157                TypeId::of::<T>(),
4158                ref_counts.clone(),
4159            ),
4160            view_type: PhantomData,
4161        }
4162    }
4163
4164    pub fn downgrade(&self) -> WeakViewHandle<T> {
4165        WeakViewHandle::new(self.window_id, self.view_id)
4166    }
4167
4168    pub fn into_any(self) -> AnyViewHandle {
4169        self.any_handle
4170    }
4171
4172    pub fn window_id(&self) -> usize {
4173        self.window_id
4174    }
4175
4176    pub fn id(&self) -> usize {
4177        self.view_id
4178    }
4179
4180    pub fn read<'a, C: ReadView>(&self, cx: &'a C) -> &'a T {
4181        cx.read_view(self)
4182    }
4183
4184    pub fn read_with<C, F, S>(&self, cx: &C, read: F) -> S
4185    where
4186        C: ReadViewWith,
4187        F: FnOnce(&T, &AppContext) -> S,
4188    {
4189        let mut read = Some(read);
4190        cx.read_view_with(self, &mut |view, cx| {
4191            let read = read.take().unwrap();
4192            read(view, cx)
4193        })
4194    }
4195
4196    pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
4197    where
4198        C: UpdateView,
4199        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
4200    {
4201        let mut update = Some(update);
4202        cx.update_view(self, &mut |view, cx| {
4203            let update = update.take().unwrap();
4204            update(view, cx)
4205        })
4206    }
4207
4208    pub fn defer<C, F>(&self, cx: &mut C, update: F)
4209    where
4210        C: AsMut<AppContext>,
4211        F: 'static + FnOnce(&mut T, &mut ViewContext<T>),
4212    {
4213        let this = self.clone();
4214        cx.as_mut().defer(move |cx| {
4215            this.update(cx, |view, cx| update(view, cx));
4216        });
4217    }
4218
4219    pub fn is_focused(&self, cx: &AppContext) -> bool {
4220        cx.focused_view_id(self.window_id)
4221            .map_or(false, |focused_id| focused_id == self.view_id)
4222    }
4223}
4224
4225impl<T: View> Clone for ViewHandle<T> {
4226    fn clone(&self) -> Self {
4227        ViewHandle::new(self.window_id, self.view_id, &self.ref_counts)
4228    }
4229}
4230
4231impl<T> PartialEq for ViewHandle<T> {
4232    fn eq(&self, other: &Self) -> bool {
4233        self.window_id == other.window_id && self.view_id == other.view_id
4234    }
4235}
4236
4237impl<T> PartialEq<WeakViewHandle<T>> for ViewHandle<T> {
4238    fn eq(&self, other: &WeakViewHandle<T>) -> bool {
4239        self.window_id == other.window_id && self.view_id == other.view_id
4240    }
4241}
4242
4243impl<T> PartialEq<ViewHandle<T>> for WeakViewHandle<T> {
4244    fn eq(&self, other: &ViewHandle<T>) -> bool {
4245        self.window_id == other.window_id && self.view_id == other.view_id
4246    }
4247}
4248
4249impl<T> Eq for ViewHandle<T> {}
4250
4251impl<T> Hash for ViewHandle<T> {
4252    fn hash<H: Hasher>(&self, state: &mut H) {
4253        self.window_id.hash(state);
4254        self.view_id.hash(state);
4255    }
4256}
4257
4258impl<T> Debug for ViewHandle<T> {
4259    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
4260        f.debug_struct(&format!("ViewHandle<{}>", type_name::<T>()))
4261            .field("window_id", &self.window_id)
4262            .field("view_id", &self.view_id)
4263            .finish()
4264    }
4265}
4266
4267impl<T: View> Handle<T> for ViewHandle<T> {
4268    type Weak = WeakViewHandle<T>;
4269
4270    fn id(&self) -> usize {
4271        self.view_id
4272    }
4273
4274    fn location(&self) -> EntityLocation {
4275        EntityLocation::View(self.window_id, self.view_id)
4276    }
4277
4278    fn downgrade(&self) -> Self::Weak {
4279        self.downgrade()
4280    }
4281
4282    fn upgrade_from(weak: &Self::Weak, cx: &AppContext) -> Option<Self>
4283    where
4284        Self: Sized,
4285    {
4286        weak.upgrade(cx)
4287    }
4288}
4289
4290pub struct AnyViewHandle {
4291    window_id: usize,
4292    view_id: usize,
4293    view_type: TypeId,
4294    ref_counts: Arc<Mutex<RefCounts>>,
4295
4296    #[cfg(any(test, feature = "test-support"))]
4297    handle_id: usize,
4298}
4299
4300impl AnyViewHandle {
4301    fn new(
4302        window_id: usize,
4303        view_id: usize,
4304        view_type: TypeId,
4305        ref_counts: Arc<Mutex<RefCounts>>,
4306    ) -> Self {
4307        ref_counts.lock().inc_view(window_id, view_id);
4308
4309        #[cfg(any(test, feature = "test-support"))]
4310        let handle_id = ref_counts
4311            .lock()
4312            .leak_detector
4313            .lock()
4314            .handle_created(None, view_id);
4315
4316        Self {
4317            window_id,
4318            view_id,
4319            view_type,
4320            ref_counts,
4321            #[cfg(any(test, feature = "test-support"))]
4322            handle_id,
4323        }
4324    }
4325
4326    pub fn window_id(&self) -> usize {
4327        self.window_id
4328    }
4329
4330    pub fn id(&self) -> usize {
4331        self.view_id
4332    }
4333
4334    pub fn is<T: 'static>(&self) -> bool {
4335        TypeId::of::<T>() == self.view_type
4336    }
4337
4338    pub fn is_focused(&self, cx: &AppContext) -> bool {
4339        cx.focused_view_id(self.window_id)
4340            .map_or(false, |focused_id| focused_id == self.view_id)
4341    }
4342
4343    pub fn downcast<T: View>(self) -> Option<ViewHandle<T>> {
4344        if self.is::<T>() {
4345            Some(ViewHandle {
4346                any_handle: self,
4347                view_type: PhantomData,
4348            })
4349        } else {
4350            None
4351        }
4352    }
4353
4354    pub fn downcast_ref<T: View>(&self) -> Option<&ViewHandle<T>> {
4355        if self.is::<T>() {
4356            Some(unsafe { mem::transmute(self) })
4357        } else {
4358            None
4359        }
4360    }
4361
4362    pub fn downgrade(&self) -> AnyWeakViewHandle {
4363        AnyWeakViewHandle {
4364            window_id: self.window_id,
4365            view_id: self.view_id,
4366            view_type: self.view_type,
4367        }
4368    }
4369
4370    pub fn view_type(&self) -> TypeId {
4371        self.view_type
4372    }
4373
4374    pub fn debug_json<'a, 'b>(&self, cx: &'b WindowContext<'a, 'b>) -> serde_json::Value {
4375        cx.views
4376            .get(&(self.window_id, self.view_id))
4377            .map_or_else(|| serde_json::Value::Null, |view| view.debug_json(cx))
4378    }
4379}
4380
4381impl Clone for AnyViewHandle {
4382    fn clone(&self) -> Self {
4383        Self::new(
4384            self.window_id,
4385            self.view_id,
4386            self.view_type,
4387            self.ref_counts.clone(),
4388        )
4389    }
4390}
4391
4392impl<T> PartialEq<ViewHandle<T>> for AnyViewHandle {
4393    fn eq(&self, other: &ViewHandle<T>) -> bool {
4394        self.window_id == other.window_id && self.view_id == other.view_id
4395    }
4396}
4397
4398impl Drop for AnyViewHandle {
4399    fn drop(&mut self) {
4400        self.ref_counts
4401            .lock()
4402            .dec_view(self.window_id, self.view_id);
4403        #[cfg(any(test, feature = "test-support"))]
4404        self.ref_counts
4405            .lock()
4406            .leak_detector
4407            .lock()
4408            .handle_dropped(self.view_id, self.handle_id);
4409    }
4410}
4411
4412pub struct AnyModelHandle {
4413    model_id: usize,
4414    model_type: TypeId,
4415    ref_counts: Arc<Mutex<RefCounts>>,
4416
4417    #[cfg(any(test, feature = "test-support"))]
4418    handle_id: usize,
4419}
4420
4421impl AnyModelHandle {
4422    fn new(model_id: usize, model_type: TypeId, ref_counts: Arc<Mutex<RefCounts>>) -> Self {
4423        ref_counts.lock().inc_model(model_id);
4424
4425        #[cfg(any(test, feature = "test-support"))]
4426        let handle_id = ref_counts
4427            .lock()
4428            .leak_detector
4429            .lock()
4430            .handle_created(None, model_id);
4431
4432        Self {
4433            model_id,
4434            model_type,
4435            ref_counts,
4436
4437            #[cfg(any(test, feature = "test-support"))]
4438            handle_id,
4439        }
4440    }
4441
4442    pub fn downcast<T: Entity>(self) -> Option<ModelHandle<T>> {
4443        if self.is::<T>() {
4444            Some(ModelHandle {
4445                any_handle: self,
4446                model_type: PhantomData,
4447            })
4448        } else {
4449            None
4450        }
4451    }
4452
4453    pub fn downgrade(&self) -> AnyWeakModelHandle {
4454        AnyWeakModelHandle {
4455            model_id: self.model_id,
4456            model_type: self.model_type,
4457        }
4458    }
4459
4460    pub fn is<T: Entity>(&self) -> bool {
4461        self.model_type == TypeId::of::<T>()
4462    }
4463
4464    pub fn model_type(&self) -> TypeId {
4465        self.model_type
4466    }
4467}
4468
4469impl Clone for AnyModelHandle {
4470    fn clone(&self) -> Self {
4471        Self::new(self.model_id, self.model_type, self.ref_counts.clone())
4472    }
4473}
4474
4475impl Drop for AnyModelHandle {
4476    fn drop(&mut self) {
4477        let mut ref_counts = self.ref_counts.lock();
4478        ref_counts.dec_model(self.model_id);
4479
4480        #[cfg(any(test, feature = "test-support"))]
4481        ref_counts
4482            .leak_detector
4483            .lock()
4484            .handle_dropped(self.model_id, self.handle_id);
4485    }
4486}
4487
4488#[derive(Hash, PartialEq, Eq, Debug, Clone, Copy)]
4489pub struct AnyWeakModelHandle {
4490    model_id: usize,
4491    model_type: TypeId,
4492}
4493
4494impl AnyWeakModelHandle {
4495    pub fn upgrade(&self, cx: &impl UpgradeModelHandle) -> Option<AnyModelHandle> {
4496        cx.upgrade_any_model_handle(self)
4497    }
4498    pub fn model_type(&self) -> TypeId {
4499        self.model_type
4500    }
4501
4502    fn is<T: 'static>(&self) -> bool {
4503        TypeId::of::<T>() == self.model_type
4504    }
4505
4506    pub fn downcast<T: Entity>(self) -> Option<WeakModelHandle<T>> {
4507        if self.is::<T>() {
4508            let result = Some(WeakModelHandle {
4509                any_handle: self,
4510                model_type: PhantomData,
4511            });
4512
4513            result
4514        } else {
4515            None
4516        }
4517    }
4518}
4519
4520#[derive(Debug, Copy)]
4521pub struct WeakViewHandle<T> {
4522    any_handle: AnyWeakViewHandle,
4523    view_type: PhantomData<T>,
4524}
4525
4526impl<T> WeakHandle for WeakViewHandle<T> {
4527    fn id(&self) -> usize {
4528        self.view_id
4529    }
4530}
4531
4532impl<T: View> WeakViewHandle<T> {
4533    fn new(window_id: usize, view_id: usize) -> Self {
4534        Self {
4535            any_handle: AnyWeakViewHandle {
4536                window_id,
4537                view_id,
4538                view_type: TypeId::of::<T>(),
4539            },
4540            view_type: PhantomData,
4541        }
4542    }
4543
4544    pub fn id(&self) -> usize {
4545        self.view_id
4546    }
4547
4548    pub fn window_id(&self) -> usize {
4549        self.window_id
4550    }
4551
4552    pub fn into_any(self) -> AnyWeakViewHandle {
4553        self.any_handle
4554    }
4555
4556    pub fn upgrade(&self, cx: &impl UpgradeViewHandle) -> Option<ViewHandle<T>> {
4557        cx.upgrade_view_handle(self)
4558    }
4559}
4560
4561impl<T> Deref for WeakViewHandle<T> {
4562    type Target = AnyWeakViewHandle;
4563
4564    fn deref(&self) -> &Self::Target {
4565        &self.any_handle
4566    }
4567}
4568
4569impl<T> Clone for WeakViewHandle<T> {
4570    fn clone(&self) -> Self {
4571        Self {
4572            any_handle: self.any_handle.clone(),
4573            view_type: PhantomData,
4574        }
4575    }
4576}
4577
4578impl<T> PartialEq for WeakViewHandle<T> {
4579    fn eq(&self, other: &Self) -> bool {
4580        self.window_id == other.window_id && self.view_id == other.view_id
4581    }
4582}
4583
4584impl<T> Eq for WeakViewHandle<T> {}
4585
4586impl<T> Hash for WeakViewHandle<T> {
4587    fn hash<H: Hasher>(&self, state: &mut H) {
4588        self.any_handle.hash(state);
4589    }
4590}
4591
4592#[derive(Debug, Clone, Copy)]
4593pub struct AnyWeakViewHandle {
4594    window_id: usize,
4595    view_id: usize,
4596    view_type: TypeId,
4597}
4598
4599impl AnyWeakViewHandle {
4600    pub fn id(&self) -> usize {
4601        self.view_id
4602    }
4603
4604    pub fn upgrade(&self, cx: &impl UpgradeViewHandle) -> Option<AnyViewHandle> {
4605        cx.upgrade_any_view_handle(self)
4606    }
4607}
4608
4609impl Hash for AnyWeakViewHandle {
4610    fn hash<H: Hasher>(&self, state: &mut H) {
4611        self.window_id.hash(state);
4612        self.view_id.hash(state);
4613        self.view_type.hash(state);
4614    }
4615}
4616
4617#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
4618pub struct ElementStateId {
4619    view_id: usize,
4620    element_id: usize,
4621    tag: TypeId,
4622}
4623
4624pub struct ElementStateHandle<T> {
4625    value_type: PhantomData<T>,
4626    id: ElementStateId,
4627    ref_counts: Weak<Mutex<RefCounts>>,
4628}
4629
4630impl<T: 'static> ElementStateHandle<T> {
4631    fn new(id: ElementStateId, frame_id: usize, ref_counts: &Arc<Mutex<RefCounts>>) -> Self {
4632        ref_counts.lock().inc_element_state(id, frame_id);
4633        Self {
4634            value_type: PhantomData,
4635            id,
4636            ref_counts: Arc::downgrade(ref_counts),
4637        }
4638    }
4639
4640    pub fn id(&self) -> ElementStateId {
4641        self.id
4642    }
4643
4644    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a T {
4645        cx.element_states
4646            .get(&self.id)
4647            .unwrap()
4648            .downcast_ref()
4649            .unwrap()
4650    }
4651
4652    pub fn update<C, D, R>(&self, cx: &mut C, f: impl FnOnce(&mut T, &mut C) -> R) -> R
4653    where
4654        C: DerefMut<Target = D>,
4655        D: DerefMut<Target = AppContext>,
4656    {
4657        let mut element_state = cx.deref_mut().element_states.remove(&self.id).unwrap();
4658        let result = f(element_state.downcast_mut().unwrap(), cx);
4659        cx.deref_mut().element_states.insert(self.id, element_state);
4660        result
4661    }
4662}
4663
4664impl<T> Drop for ElementStateHandle<T> {
4665    fn drop(&mut self) {
4666        if let Some(ref_counts) = self.ref_counts.upgrade() {
4667            ref_counts.lock().dec_element_state(self.id);
4668        }
4669    }
4670}
4671
4672#[must_use]
4673pub enum Subscription {
4674    Subscription(callback_collection::Subscription<usize, SubscriptionCallback>),
4675    Observation(callback_collection::Subscription<usize, ObservationCallback>),
4676    GlobalSubscription(callback_collection::Subscription<TypeId, GlobalSubscriptionCallback>),
4677    GlobalObservation(callback_collection::Subscription<TypeId, GlobalObservationCallback>),
4678    FocusObservation(callback_collection::Subscription<usize, FocusObservationCallback>),
4679    WindowActivationObservation(callback_collection::Subscription<usize, WindowActivationCallback>),
4680    WindowFullscreenObservation(callback_collection::Subscription<usize, WindowFullscreenCallback>),
4681    WindowBoundsObservation(callback_collection::Subscription<usize, WindowBoundsCallback>),
4682    KeystrokeObservation(callback_collection::Subscription<usize, KeystrokeCallback>),
4683    ReleaseObservation(callback_collection::Subscription<usize, ReleaseObservationCallback>),
4684    ActionObservation(callback_collection::Subscription<(), ActionObservationCallback>),
4685    ActiveLabeledTasksObservation(
4686        callback_collection::Subscription<(), ActiveLabeledTasksCallback>,
4687    ),
4688}
4689
4690impl Subscription {
4691    pub fn id(&self) -> usize {
4692        match self {
4693            Subscription::Subscription(subscription) => subscription.id(),
4694            Subscription::Observation(subscription) => subscription.id(),
4695            Subscription::GlobalSubscription(subscription) => subscription.id(),
4696            Subscription::GlobalObservation(subscription) => subscription.id(),
4697            Subscription::FocusObservation(subscription) => subscription.id(),
4698            Subscription::WindowActivationObservation(subscription) => subscription.id(),
4699            Subscription::WindowFullscreenObservation(subscription) => subscription.id(),
4700            Subscription::WindowBoundsObservation(subscription) => subscription.id(),
4701            Subscription::KeystrokeObservation(subscription) => subscription.id(),
4702            Subscription::ReleaseObservation(subscription) => subscription.id(),
4703            Subscription::ActionObservation(subscription) => subscription.id(),
4704            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.id(),
4705        }
4706    }
4707
4708    pub fn detach(&mut self) {
4709        match self {
4710            Subscription::Subscription(subscription) => subscription.detach(),
4711            Subscription::GlobalSubscription(subscription) => subscription.detach(),
4712            Subscription::Observation(subscription) => subscription.detach(),
4713            Subscription::GlobalObservation(subscription) => subscription.detach(),
4714            Subscription::FocusObservation(subscription) => subscription.detach(),
4715            Subscription::KeystrokeObservation(subscription) => subscription.detach(),
4716            Subscription::WindowActivationObservation(subscription) => subscription.detach(),
4717            Subscription::WindowFullscreenObservation(subscription) => subscription.detach(),
4718            Subscription::WindowBoundsObservation(subscription) => subscription.detach(),
4719            Subscription::ReleaseObservation(subscription) => subscription.detach(),
4720            Subscription::ActionObservation(subscription) => subscription.detach(),
4721            Subscription::ActiveLabeledTasksObservation(subscription) => subscription.detach(),
4722        }
4723    }
4724}
4725
4726#[cfg(test)]
4727mod tests {
4728    use super::*;
4729    use crate::{
4730        actions,
4731        elements::*,
4732        impl_actions,
4733        platform::{MouseButton, MouseButtonEvent},
4734        window::ChildView,
4735    };
4736    use itertools::Itertools;
4737    use postage::{sink::Sink, stream::Stream};
4738    use serde::Deserialize;
4739    use smol::future::poll_once;
4740    use std::{
4741        cell::Cell,
4742        sync::atomic::{AtomicBool, AtomicUsize, Ordering::SeqCst},
4743    };
4744
4745    #[crate::test(self)]
4746    fn test_model_handles(cx: &mut AppContext) {
4747        struct Model {
4748            other: Option<ModelHandle<Model>>,
4749            events: Vec<String>,
4750        }
4751
4752        impl Entity for Model {
4753            type Event = usize;
4754        }
4755
4756        impl Model {
4757            fn new(other: Option<ModelHandle<Self>>, cx: &mut ModelContext<Self>) -> Self {
4758                if let Some(other) = other.as_ref() {
4759                    cx.observe(other, |me, _, _| {
4760                        me.events.push("notified".into());
4761                    })
4762                    .detach();
4763                    cx.subscribe(other, |me, _, event, _| {
4764                        me.events.push(format!("observed event {}", event));
4765                    })
4766                    .detach();
4767                }
4768
4769                Self {
4770                    other,
4771                    events: Vec::new(),
4772                }
4773            }
4774        }
4775
4776        let handle_1 = cx.add_model(|cx| Model::new(None, cx));
4777        let handle_2 = cx.add_model(|cx| Model::new(Some(handle_1.clone()), cx));
4778        assert_eq!(cx.models.len(), 2);
4779
4780        handle_1.update(cx, |model, cx| {
4781            model.events.push("updated".into());
4782            cx.emit(1);
4783            cx.notify();
4784            cx.emit(2);
4785        });
4786        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
4787        assert_eq!(
4788            handle_2.read(cx).events,
4789            vec![
4790                "observed event 1".to_string(),
4791                "notified".to_string(),
4792                "observed event 2".to_string(),
4793            ]
4794        );
4795
4796        handle_2.update(cx, |model, _| {
4797            drop(handle_1);
4798            model.other.take();
4799        });
4800
4801        assert_eq!(cx.models.len(), 1);
4802        assert!(cx.subscriptions.is_empty());
4803        assert!(cx.observations.is_empty());
4804    }
4805
4806    #[crate::test(self)]
4807    fn test_model_events(cx: &mut AppContext) {
4808        #[derive(Default)]
4809        struct Model {
4810            events: Vec<usize>,
4811        }
4812
4813        impl Entity for Model {
4814            type Event = usize;
4815        }
4816
4817        let handle_1 = cx.add_model(|_| Model::default());
4818        let handle_2 = cx.add_model(|_| Model::default());
4819
4820        handle_1.update(cx, |_, cx| {
4821            cx.subscribe(&handle_2, move |model: &mut Model, emitter, event, cx| {
4822                model.events.push(*event);
4823
4824                cx.subscribe(&emitter, |model, _, event, _| {
4825                    model.events.push(*event * 2);
4826                })
4827                .detach();
4828            })
4829            .detach();
4830        });
4831
4832        handle_2.update(cx, |_, c| c.emit(7));
4833        assert_eq!(handle_1.read(cx).events, vec![7]);
4834
4835        handle_2.update(cx, |_, c| c.emit(5));
4836        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10]);
4837    }
4838
4839    #[crate::test(self)]
4840    fn test_model_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
4841        #[derive(Default)]
4842        struct Model;
4843
4844        impl Entity for Model {
4845            type Event = ();
4846        }
4847
4848        let events = Rc::new(RefCell::new(Vec::new()));
4849        cx.add_model(|cx| {
4850            drop(cx.subscribe(&cx.handle(), {
4851                let events = events.clone();
4852                move |_, _, _, _| events.borrow_mut().push("dropped before flush")
4853            }));
4854            cx.subscribe(&cx.handle(), {
4855                let events = events.clone();
4856                move |_, _, _, _| events.borrow_mut().push("before emit")
4857            })
4858            .detach();
4859            cx.emit(());
4860            cx.subscribe(&cx.handle(), {
4861                let events = events.clone();
4862                move |_, _, _, _| events.borrow_mut().push("after emit")
4863            })
4864            .detach();
4865            Model
4866        });
4867        assert_eq!(*events.borrow(), ["before emit"]);
4868    }
4869
4870    #[crate::test(self)]
4871    fn test_observe_and_notify_from_model(cx: &mut AppContext) {
4872        #[derive(Default)]
4873        struct Model {
4874            count: usize,
4875            events: Vec<usize>,
4876        }
4877
4878        impl Entity for Model {
4879            type Event = ();
4880        }
4881
4882        let handle_1 = cx.add_model(|_| Model::default());
4883        let handle_2 = cx.add_model(|_| Model::default());
4884
4885        handle_1.update(cx, |_, c| {
4886            c.observe(&handle_2, move |model, observed, c| {
4887                model.events.push(observed.read(c).count);
4888                c.observe(&observed, |model, observed, c| {
4889                    model.events.push(observed.read(c).count * 2);
4890                })
4891                .detach();
4892            })
4893            .detach();
4894        });
4895
4896        handle_2.update(cx, |model, c| {
4897            model.count = 7;
4898            c.notify()
4899        });
4900        assert_eq!(handle_1.read(cx).events, vec![7]);
4901
4902        handle_2.update(cx, |model, c| {
4903            model.count = 5;
4904            c.notify()
4905        });
4906        assert_eq!(handle_1.read(cx).events, vec![7, 5, 10])
4907    }
4908
4909    #[crate::test(self)]
4910    fn test_model_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
4911        #[derive(Default)]
4912        struct Model;
4913
4914        impl Entity for Model {
4915            type Event = ();
4916        }
4917
4918        let events = Rc::new(RefCell::new(Vec::new()));
4919        cx.add_model(|cx| {
4920            drop(cx.observe(&cx.handle(), {
4921                let events = events.clone();
4922                move |_, _, _| events.borrow_mut().push("dropped before flush")
4923            }));
4924            cx.observe(&cx.handle(), {
4925                let events = events.clone();
4926                move |_, _, _| events.borrow_mut().push("before notify")
4927            })
4928            .detach();
4929            cx.notify();
4930            cx.observe(&cx.handle(), {
4931                let events = events.clone();
4932                move |_, _, _| events.borrow_mut().push("after notify")
4933            })
4934            .detach();
4935            Model
4936        });
4937        assert_eq!(*events.borrow(), ["before notify"]);
4938    }
4939
4940    #[crate::test(self)]
4941    fn test_defer_and_after_window_update(cx: &mut AppContext) {
4942        struct View {
4943            render_count: usize,
4944        }
4945
4946        impl Entity for View {
4947            type Event = usize;
4948        }
4949
4950        impl super::View for View {
4951            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
4952                post_inc(&mut self.render_count);
4953                Empty::new().boxed()
4954            }
4955
4956            fn ui_name() -> &'static str {
4957                "View"
4958            }
4959        }
4960
4961        let (_, view) = cx.add_window(Default::default(), |_| View { render_count: 0 });
4962        let called_defer = Rc::new(AtomicBool::new(false));
4963        let called_after_window_update = Rc::new(AtomicBool::new(false));
4964
4965        view.update(cx, |this, cx| {
4966            assert_eq!(this.render_count, 1);
4967            cx.defer({
4968                let called_defer = called_defer.clone();
4969                move |this, _| {
4970                    assert_eq!(this.render_count, 1);
4971                    called_defer.store(true, SeqCst);
4972                }
4973            });
4974            cx.after_window_update({
4975                let called_after_window_update = called_after_window_update.clone();
4976                move |this, cx| {
4977                    assert_eq!(this.render_count, 2);
4978                    called_after_window_update.store(true, SeqCst);
4979                    cx.notify();
4980                }
4981            });
4982            assert!(!called_defer.load(SeqCst));
4983            assert!(!called_after_window_update.load(SeqCst));
4984            cx.notify();
4985        });
4986
4987        assert!(called_defer.load(SeqCst));
4988        assert!(called_after_window_update.load(SeqCst));
4989        assert_eq!(view.read(cx).render_count, 3);
4990    }
4991
4992    #[crate::test(self)]
4993    fn test_view_handles(cx: &mut AppContext) {
4994        struct View {
4995            other: Option<ViewHandle<View>>,
4996            events: Vec<String>,
4997        }
4998
4999        impl Entity for View {
5000            type Event = usize;
5001        }
5002
5003        impl super::View for View {
5004            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
5005                Empty::new().boxed()
5006            }
5007
5008            fn ui_name() -> &'static str {
5009                "View"
5010            }
5011        }
5012
5013        impl View {
5014            fn new(other: Option<ViewHandle<View>>, cx: &mut ViewContext<Self>) -> Self {
5015                if let Some(other) = other.as_ref() {
5016                    cx.subscribe(other, |me, _, event, _| {
5017                        me.events.push(format!("observed event {}", event));
5018                    })
5019                    .detach();
5020                }
5021                Self {
5022                    other,
5023                    events: Vec::new(),
5024                }
5025            }
5026        }
5027
5028        let (_, root_view) = cx.add_window(Default::default(), |cx| View::new(None, cx));
5029        let handle_1 = cx.add_view(&root_view, |cx| View::new(None, cx));
5030        let handle_2 = cx.add_view(&root_view, |cx| View::new(Some(handle_1.clone()), cx));
5031        assert_eq!(cx.views.len(), 3);
5032
5033        handle_1.update(cx, |view, cx| {
5034            view.events.push("updated".into());
5035            cx.emit(1);
5036            cx.emit(2);
5037        });
5038        assert_eq!(handle_1.read(cx).events, vec!["updated".to_string()]);
5039        assert_eq!(
5040            handle_2.read(cx).events,
5041            vec![
5042                "observed event 1".to_string(),
5043                "observed event 2".to_string(),
5044            ]
5045        );
5046
5047        handle_2.update(cx, |view, _| {
5048            drop(handle_1);
5049            view.other.take();
5050        });
5051
5052        assert_eq!(cx.views.len(), 2);
5053        assert!(cx.subscriptions.is_empty());
5054        assert!(cx.observations.is_empty());
5055    }
5056
5057    #[crate::test(self)]
5058    fn test_add_window(cx: &mut AppContext) {
5059        struct View {
5060            mouse_down_count: Arc<AtomicUsize>,
5061        }
5062
5063        impl Entity for View {
5064            type Event = ();
5065        }
5066
5067        impl super::View for View {
5068            fn render(&mut self, cx: &mut ViewContext<Self>) -> Element<Self> {
5069                enum Handler {}
5070                let mouse_down_count = self.mouse_down_count.clone();
5071                MouseEventHandler::<Handler, _>::new(0, cx, |_, _| Empty::new().boxed())
5072                    .on_down(MouseButton::Left, move |_, _, _| {
5073                        mouse_down_count.fetch_add(1, SeqCst);
5074                    })
5075                    .boxed()
5076            }
5077
5078            fn ui_name() -> &'static str {
5079                "View"
5080            }
5081        }
5082
5083        let mouse_down_count = Arc::new(AtomicUsize::new(0));
5084        let (window_id, _) = cx.add_window(Default::default(), |_| View {
5085            mouse_down_count: mouse_down_count.clone(),
5086        });
5087
5088        cx.update_window(window_id, |cx| {
5089            // Ensure window's root element is in a valid lifecycle state.
5090            cx.dispatch_event(
5091                Event::MouseDown(MouseButtonEvent {
5092                    position: Default::default(),
5093                    button: MouseButton::Left,
5094                    modifiers: Default::default(),
5095                    click_count: 1,
5096                }),
5097                false,
5098            );
5099            assert_eq!(mouse_down_count.load(SeqCst), 1);
5100        });
5101    }
5102
5103    #[crate::test(self)]
5104    fn test_entity_release_hooks(cx: &mut AppContext) {
5105        struct Model {
5106            released: Rc<Cell<bool>>,
5107        }
5108
5109        struct View {
5110            released: Rc<Cell<bool>>,
5111        }
5112
5113        impl Entity for Model {
5114            type Event = ();
5115
5116            fn release(&mut self, _: &mut AppContext) {
5117                self.released.set(true);
5118            }
5119        }
5120
5121        impl Entity for View {
5122            type Event = ();
5123
5124            fn release(&mut self, _: &mut AppContext) {
5125                self.released.set(true);
5126            }
5127        }
5128
5129        impl super::View for View {
5130            fn ui_name() -> &'static str {
5131                "View"
5132            }
5133
5134            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
5135                Empty::new().boxed()
5136            }
5137        }
5138
5139        let model_released = Rc::new(Cell::new(false));
5140        let model_release_observed = Rc::new(Cell::new(false));
5141        let view_released = Rc::new(Cell::new(false));
5142        let view_release_observed = Rc::new(Cell::new(false));
5143
5144        let model = cx.add_model(|_| Model {
5145            released: model_released.clone(),
5146        });
5147        let (window_id, view) = cx.add_window(Default::default(), |_| View {
5148            released: view_released.clone(),
5149        });
5150        assert!(!model_released.get());
5151        assert!(!view_released.get());
5152
5153        cx.observe_release(&model, {
5154            let model_release_observed = model_release_observed.clone();
5155            move |_, _| model_release_observed.set(true)
5156        })
5157        .detach();
5158        cx.observe_release(&view, {
5159            let view_release_observed = view_release_observed.clone();
5160            move |_, _| view_release_observed.set(true)
5161        })
5162        .detach();
5163
5164        cx.update(move |_| {
5165            drop(model);
5166        });
5167        assert!(model_released.get());
5168        assert!(model_release_observed.get());
5169
5170        drop(view);
5171        cx.remove_window(window_id);
5172        assert!(view_released.get());
5173        assert!(view_release_observed.get());
5174    }
5175
5176    #[crate::test(self)]
5177    fn test_view_events(cx: &mut AppContext) {
5178        struct Model;
5179
5180        impl Entity for Model {
5181            type Event = String;
5182        }
5183
5184        let (_, handle_1) = cx.add_window(Default::default(), |_| TestView::default());
5185        let handle_2 = cx.add_view(&handle_1, |_| TestView::default());
5186        let handle_3 = cx.add_model(|_| Model);
5187
5188        handle_1.update(cx, |_, cx| {
5189            cx.subscribe(&handle_2, move |me, emitter, event, cx| {
5190                me.events.push(event.clone());
5191
5192                cx.subscribe(&emitter, |me, _, event, _| {
5193                    me.events.push(format!("{event} from inner"));
5194                })
5195                .detach();
5196            })
5197            .detach();
5198
5199            cx.subscribe(&handle_3, |me, _, event, _| {
5200                me.events.push(event.clone());
5201            })
5202            .detach();
5203        });
5204
5205        handle_2.update(cx, |_, c| c.emit("7".into()));
5206        assert_eq!(handle_1.read(cx).events, vec!["7"]);
5207
5208        handle_2.update(cx, |_, c| c.emit("5".into()));
5209        assert_eq!(handle_1.read(cx).events, vec!["7", "5", "5 from inner"]);
5210
5211        handle_3.update(cx, |_, c| c.emit("9".into()));
5212        assert_eq!(
5213            handle_1.read(cx).events,
5214            vec!["7", "5", "5 from inner", "9"]
5215        );
5216    }
5217
5218    #[crate::test(self)]
5219    fn test_global_events(cx: &mut AppContext) {
5220        #[derive(Clone, Debug, Eq, PartialEq)]
5221        struct GlobalEvent(u64);
5222
5223        let events = Rc::new(RefCell::new(Vec::new()));
5224        let first_subscription;
5225        let second_subscription;
5226
5227        {
5228            let events = events.clone();
5229            first_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
5230                events.borrow_mut().push(("First", e.clone()));
5231            });
5232        }
5233
5234        {
5235            let events = events.clone();
5236            second_subscription = cx.subscribe_global(move |e: &GlobalEvent, _| {
5237                events.borrow_mut().push(("Second", e.clone()));
5238            });
5239        }
5240
5241        cx.update(|cx| {
5242            cx.emit_global(GlobalEvent(1));
5243            cx.emit_global(GlobalEvent(2));
5244        });
5245
5246        drop(first_subscription);
5247
5248        cx.update(|cx| {
5249            cx.emit_global(GlobalEvent(3));
5250        });
5251
5252        drop(second_subscription);
5253
5254        cx.update(|cx| {
5255            cx.emit_global(GlobalEvent(4));
5256        });
5257
5258        assert_eq!(
5259            &*events.borrow(),
5260            &[
5261                ("First", GlobalEvent(1)),
5262                ("Second", GlobalEvent(1)),
5263                ("First", GlobalEvent(2)),
5264                ("Second", GlobalEvent(2)),
5265                ("Second", GlobalEvent(3)),
5266            ]
5267        );
5268    }
5269
5270    #[crate::test(self)]
5271    fn test_global_events_emitted_before_subscription_in_same_update_cycle(cx: &mut AppContext) {
5272        let events = Rc::new(RefCell::new(Vec::new()));
5273        cx.update(|cx| {
5274            {
5275                let events = events.clone();
5276                drop(cx.subscribe_global(move |_: &(), _| {
5277                    events.borrow_mut().push("dropped before emit");
5278                }));
5279            }
5280
5281            {
5282                let events = events.clone();
5283                cx.subscribe_global(move |_: &(), _| {
5284                    events.borrow_mut().push("before emit");
5285                })
5286                .detach();
5287            }
5288
5289            cx.emit_global(());
5290
5291            {
5292                let events = events.clone();
5293                cx.subscribe_global(move |_: &(), _| {
5294                    events.borrow_mut().push("after emit");
5295                })
5296                .detach();
5297            }
5298        });
5299
5300        assert_eq!(*events.borrow(), ["before emit"]);
5301    }
5302
5303    #[crate::test(self)]
5304    fn test_global_nested_events(cx: &mut AppContext) {
5305        #[derive(Clone, Debug, Eq, PartialEq)]
5306        struct GlobalEvent(u64);
5307
5308        let events = Rc::new(RefCell::new(Vec::new()));
5309
5310        {
5311            let events = events.clone();
5312            cx.subscribe_global(move |e: &GlobalEvent, cx| {
5313                events.borrow_mut().push(("Outer", e.clone()));
5314
5315                if e.0 == 1 {
5316                    let events = events.clone();
5317                    cx.subscribe_global(move |e: &GlobalEvent, _| {
5318                        events.borrow_mut().push(("Inner", e.clone()));
5319                    })
5320                    .detach();
5321                }
5322            })
5323            .detach();
5324        }
5325
5326        cx.update(|cx| {
5327            cx.emit_global(GlobalEvent(1));
5328            cx.emit_global(GlobalEvent(2));
5329            cx.emit_global(GlobalEvent(3));
5330        });
5331        cx.update(|cx| {
5332            cx.emit_global(GlobalEvent(4));
5333        });
5334
5335        assert_eq!(
5336            &*events.borrow(),
5337            &[
5338                ("Outer", GlobalEvent(1)),
5339                ("Outer", GlobalEvent(2)),
5340                ("Outer", GlobalEvent(3)),
5341                ("Outer", GlobalEvent(4)),
5342                ("Inner", GlobalEvent(4)),
5343            ]
5344        );
5345    }
5346
5347    #[crate::test(self)]
5348    fn test_global(cx: &mut AppContext) {
5349        type Global = usize;
5350
5351        let observation_count = Rc::new(RefCell::new(0));
5352        let subscription = cx.observe_global::<Global, _>({
5353            let observation_count = observation_count.clone();
5354            move |_| {
5355                *observation_count.borrow_mut() += 1;
5356            }
5357        });
5358
5359        assert!(!cx.has_global::<Global>());
5360        assert_eq!(cx.default_global::<Global>(), &0);
5361        assert_eq!(*observation_count.borrow(), 1);
5362        assert!(cx.has_global::<Global>());
5363        assert_eq!(
5364            cx.update_global::<Global, _, _>(|global, _| {
5365                *global = 1;
5366                "Update Result"
5367            }),
5368            "Update Result"
5369        );
5370        assert_eq!(*observation_count.borrow(), 2);
5371        assert_eq!(cx.global::<Global>(), &1);
5372
5373        drop(subscription);
5374        cx.update_global::<Global, _, _>(|global, _| {
5375            *global = 2;
5376        });
5377        assert_eq!(*observation_count.borrow(), 2);
5378
5379        type OtherGlobal = f32;
5380
5381        let observation_count = Rc::new(RefCell::new(0));
5382        cx.observe_global::<OtherGlobal, _>({
5383            let observation_count = observation_count.clone();
5384            move |_| {
5385                *observation_count.borrow_mut() += 1;
5386            }
5387        })
5388        .detach();
5389
5390        assert_eq!(
5391            cx.update_default_global::<OtherGlobal, _, _>(|global, _| {
5392                assert_eq!(global, &0.0);
5393                *global = 2.0;
5394                "Default update result"
5395            }),
5396            "Default update result"
5397        );
5398        assert_eq!(cx.global::<OtherGlobal>(), &2.0);
5399        assert_eq!(*observation_count.borrow(), 1);
5400    }
5401
5402    #[crate::test(self)]
5403    fn test_dropping_subscribers(cx: &mut AppContext) {
5404        struct Model;
5405
5406        impl Entity for Model {
5407            type Event = ();
5408        }
5409
5410        let (_, root_view) = cx.add_window(Default::default(), |_| TestView::default());
5411        let observing_view = cx.add_view(&root_view, |_| TestView::default());
5412        let emitting_view = cx.add_view(&root_view, |_| TestView::default());
5413        let observing_model = cx.add_model(|_| Model);
5414        let observed_model = cx.add_model(|_| Model);
5415
5416        observing_view.update(cx, |_, cx| {
5417            cx.subscribe(&emitting_view, |_, _, _, _| {}).detach();
5418            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5419        });
5420        observing_model.update(cx, |_, cx| {
5421            cx.subscribe(&observed_model, |_, _, _, _| {}).detach();
5422        });
5423
5424        cx.update(|_| {
5425            drop(observing_view);
5426            drop(observing_model);
5427        });
5428
5429        emitting_view.update(cx, |_, cx| cx.emit(Default::default()));
5430        observed_model.update(cx, |_, cx| cx.emit(()));
5431    }
5432
5433    #[crate::test(self)]
5434    fn test_view_emit_before_subscribe_in_same_update_cycle(cx: &mut AppContext) {
5435        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5436            drop(cx.subscribe(&cx.handle(), {
5437                move |this, _, _, _| this.events.push("dropped before flush".into())
5438            }));
5439            cx.subscribe(&cx.handle(), {
5440                move |this, _, _, _| this.events.push("before emit".into())
5441            })
5442            .detach();
5443            cx.emit("the event".into());
5444            cx.subscribe(&cx.handle(), {
5445                move |this, _, _, _| this.events.push("after emit".into())
5446            })
5447            .detach();
5448            TestView { events: Vec::new() }
5449        });
5450
5451        assert_eq!(view.read(cx).events, ["before emit"]);
5452    }
5453
5454    #[crate::test(self)]
5455    fn test_observe_and_notify_from_view(cx: &mut AppContext) {
5456        #[derive(Default)]
5457        struct Model {
5458            state: String,
5459        }
5460
5461        impl Entity for Model {
5462            type Event = ();
5463        }
5464
5465        let (_, view) = cx.add_window(Default::default(), |_| TestView::default());
5466        let model = cx.add_model(|_| Model {
5467            state: "old-state".into(),
5468        });
5469
5470        view.update(cx, |_, c| {
5471            c.observe(&model, |me, observed, cx| {
5472                me.events.push(observed.read(cx).state.clone())
5473            })
5474            .detach();
5475        });
5476
5477        model.update(cx, |model, cx| {
5478            model.state = "new-state".into();
5479            cx.notify();
5480        });
5481        assert_eq!(view.read(cx).events, vec!["new-state"]);
5482    }
5483
5484    #[crate::test(self)]
5485    fn test_view_notify_before_observe_in_same_update_cycle(cx: &mut AppContext) {
5486        let (_, view) = cx.add_window::<TestView, _>(Default::default(), |cx| {
5487            drop(cx.observe(&cx.handle(), {
5488                move |this, _, _| this.events.push("dropped before flush".into())
5489            }));
5490            cx.observe(&cx.handle(), {
5491                move |this, _, _| this.events.push("before notify".into())
5492            })
5493            .detach();
5494            cx.notify();
5495            cx.observe(&cx.handle(), {
5496                move |this, _, _| this.events.push("after notify".into())
5497            })
5498            .detach();
5499            TestView { events: Vec::new() }
5500        });
5501
5502        assert_eq!(view.read(cx).events, ["before notify"]);
5503    }
5504
5505    #[crate::test(self)]
5506    fn test_notify_and_drop_observe_subscription_in_same_update_cycle(cx: &mut AppContext) {
5507        struct Model;
5508        impl Entity for Model {
5509            type Event = ();
5510        }
5511
5512        let model = cx.add_model(|_| Model);
5513        let (_, view) = cx.add_window(Default::default(), |_| TestView::default());
5514
5515        view.update(cx, |_, cx| {
5516            model.update(cx, |_, cx| cx.notify());
5517            drop(cx.observe(&model, move |this, _, _| {
5518                this.events.push("model notified".into());
5519            }));
5520            model.update(cx, |_, cx| cx.notify());
5521        });
5522
5523        for _ in 0..3 {
5524            model.update(cx, |_, cx| cx.notify());
5525        }
5526
5527        assert_eq!(view.read(cx).events, Vec::<String>::new());
5528    }
5529
5530    #[crate::test(self)]
5531    fn test_dropping_observers(cx: &mut AppContext) {
5532        struct Model;
5533
5534        impl Entity for Model {
5535            type Event = ();
5536        }
5537
5538        let (_, root_view) = cx.add_window(Default::default(), |_| TestView::default());
5539        let observing_view = cx.add_view(&root_view, |_| TestView::default());
5540        let observing_model = cx.add_model(|_| Model);
5541        let observed_model = cx.add_model(|_| Model);
5542
5543        observing_view.update(cx, |_, cx| {
5544            cx.observe(&observed_model, |_, _, _| {}).detach();
5545        });
5546        observing_model.update(cx, |_, cx| {
5547            cx.observe(&observed_model, |_, _, _| {}).detach();
5548        });
5549
5550        cx.update(|_| {
5551            drop(observing_view);
5552            drop(observing_model);
5553        });
5554
5555        observed_model.update(cx, |_, cx| cx.notify());
5556    }
5557
5558    #[crate::test(self)]
5559    fn test_dropping_subscriptions_during_callback(cx: &mut AppContext) {
5560        struct Model;
5561
5562        impl Entity for Model {
5563            type Event = u64;
5564        }
5565
5566        // Events
5567        let observing_model = cx.add_model(|_| Model);
5568        let observed_model = cx.add_model(|_| Model);
5569
5570        let events = Rc::new(RefCell::new(Vec::new()));
5571
5572        observing_model.update(cx, |_, cx| {
5573            let events = events.clone();
5574            let subscription = Rc::new(RefCell::new(None));
5575            *subscription.borrow_mut() = Some(cx.subscribe(&observed_model, {
5576                let subscription = subscription.clone();
5577                move |_, _, e, _| {
5578                    subscription.borrow_mut().take();
5579                    events.borrow_mut().push(*e);
5580                }
5581            }));
5582        });
5583
5584        observed_model.update(cx, |_, cx| {
5585            cx.emit(1);
5586            cx.emit(2);
5587        });
5588
5589        assert_eq!(*events.borrow(), [1]);
5590
5591        // Global Events
5592        #[derive(Clone, Debug, Eq, PartialEq)]
5593        struct GlobalEvent(u64);
5594
5595        let events = Rc::new(RefCell::new(Vec::new()));
5596
5597        {
5598            let events = events.clone();
5599            let subscription = Rc::new(RefCell::new(None));
5600            *subscription.borrow_mut() = Some(cx.subscribe_global({
5601                let subscription = subscription.clone();
5602                move |e: &GlobalEvent, _| {
5603                    subscription.borrow_mut().take();
5604                    events.borrow_mut().push(e.clone());
5605                }
5606            }));
5607        }
5608
5609        cx.update(|cx| {
5610            cx.emit_global(GlobalEvent(1));
5611            cx.emit_global(GlobalEvent(2));
5612        });
5613
5614        assert_eq!(*events.borrow(), [GlobalEvent(1)]);
5615
5616        // Model Observation
5617        let observing_model = cx.add_model(|_| Model);
5618        let observed_model = cx.add_model(|_| Model);
5619
5620        let observation_count = Rc::new(RefCell::new(0));
5621
5622        observing_model.update(cx, |_, cx| {
5623            let observation_count = observation_count.clone();
5624            let subscription = Rc::new(RefCell::new(None));
5625            *subscription.borrow_mut() = Some(cx.observe(&observed_model, {
5626                let subscription = subscription.clone();
5627                move |_, _, _| {
5628                    subscription.borrow_mut().take();
5629                    *observation_count.borrow_mut() += 1;
5630                }
5631            }));
5632        });
5633
5634        observed_model.update(cx, |_, cx| {
5635            cx.notify();
5636        });
5637
5638        observed_model.update(cx, |_, cx| {
5639            cx.notify();
5640        });
5641
5642        assert_eq!(*observation_count.borrow(), 1);
5643
5644        // View Observation
5645        struct View;
5646
5647        impl Entity for View {
5648            type Event = ();
5649        }
5650
5651        impl super::View for View {
5652            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
5653                Empty::new().boxed()
5654            }
5655
5656            fn ui_name() -> &'static str {
5657                "View"
5658            }
5659        }
5660
5661        let (_, root_view) = cx.add_window(Default::default(), |_| View);
5662        let observing_view = cx.add_view(&root_view, |_| View);
5663        let observed_view = cx.add_view(&root_view, |_| View);
5664
5665        let observation_count = Rc::new(RefCell::new(0));
5666        observing_view.update(cx, |_, cx| {
5667            let observation_count = observation_count.clone();
5668            let subscription = Rc::new(RefCell::new(None));
5669            *subscription.borrow_mut() = Some(cx.observe(&observed_view, {
5670                let subscription = subscription.clone();
5671                move |_, _, _| {
5672                    subscription.borrow_mut().take();
5673                    *observation_count.borrow_mut() += 1;
5674                }
5675            }));
5676        });
5677
5678        observed_view.update(cx, |_, cx| {
5679            cx.notify();
5680        });
5681
5682        observed_view.update(cx, |_, cx| {
5683            cx.notify();
5684        });
5685
5686        assert_eq!(*observation_count.borrow(), 1);
5687
5688        // Global Observation
5689        let observation_count = Rc::new(RefCell::new(0));
5690        let subscription = Rc::new(RefCell::new(None));
5691        *subscription.borrow_mut() = Some(cx.observe_global::<(), _>({
5692            let observation_count = observation_count.clone();
5693            let subscription = subscription.clone();
5694            move |_| {
5695                subscription.borrow_mut().take();
5696                *observation_count.borrow_mut() += 1;
5697            }
5698        }));
5699
5700        cx.default_global::<()>();
5701        cx.set_global(());
5702        assert_eq!(*observation_count.borrow(), 1);
5703    }
5704
5705    #[crate::test(self)]
5706    fn test_focus(cx: &mut AppContext) {
5707        struct View {
5708            name: String,
5709            events: Arc<Mutex<Vec<String>>>,
5710        }
5711
5712        impl Entity for View {
5713            type Event = ();
5714        }
5715
5716        impl super::View for View {
5717            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
5718                Empty::new().boxed()
5719            }
5720
5721            fn ui_name() -> &'static str {
5722                "View"
5723            }
5724
5725            fn focus_in(&mut self, focused: AnyViewHandle, cx: &mut ViewContext<Self>) {
5726                if cx.handle().id() == focused.id() {
5727                    self.events.lock().push(format!("{} focused", &self.name));
5728                }
5729            }
5730
5731            fn focus_out(&mut self, blurred: AnyViewHandle, cx: &mut ViewContext<Self>) {
5732                if cx.handle().id() == blurred.id() {
5733                    self.events.lock().push(format!("{} blurred", &self.name));
5734                }
5735            }
5736        }
5737
5738        let view_events: Arc<Mutex<Vec<String>>> = Default::default();
5739        let (_, view_1) = cx.add_window(Default::default(), |_| View {
5740            events: view_events.clone(),
5741            name: "view 1".to_string(),
5742        });
5743        let view_2 = cx.add_view(&view_1, |_| View {
5744            events: view_events.clone(),
5745            name: "view 2".to_string(),
5746        });
5747
5748        let observed_events: Arc<Mutex<Vec<String>>> = Default::default();
5749        view_1.update(cx, |_, cx| {
5750            cx.observe_focus(&view_2, {
5751                let observed_events = observed_events.clone();
5752                move |this, view, focused, cx| {
5753                    let label = if focused { "focus" } else { "blur" };
5754                    observed_events.lock().push(format!(
5755                        "{} observed {}'s {}",
5756                        this.name,
5757                        view.read(cx).name,
5758                        label
5759                    ))
5760                }
5761            })
5762            .detach();
5763        });
5764        view_2.update(cx, |_, cx| {
5765            cx.observe_focus(&view_1, {
5766                let observed_events = observed_events.clone();
5767                move |this, view, focused, cx| {
5768                    let label = if focused { "focus" } else { "blur" };
5769                    observed_events.lock().push(format!(
5770                        "{} observed {}'s {}",
5771                        this.name,
5772                        view.read(cx).name,
5773                        label
5774                    ))
5775                }
5776            })
5777            .detach();
5778        });
5779        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5780        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5781
5782        view_1.update(cx, |_, cx| {
5783            // Ensure focus events are sent for all intermediate focuses
5784            cx.focus(&view_2);
5785            cx.focus(&view_1);
5786            cx.focus(&view_2);
5787        });
5788        assert!(cx.is_child_focused(&view_1));
5789        assert!(!cx.is_child_focused(&view_2));
5790        assert_eq!(
5791            mem::take(&mut *view_events.lock()),
5792            [
5793                "view 1 blurred",
5794                "view 2 focused",
5795                "view 2 blurred",
5796                "view 1 focused",
5797                "view 1 blurred",
5798                "view 2 focused"
5799            ],
5800        );
5801        assert_eq!(
5802            mem::take(&mut *observed_events.lock()),
5803            [
5804                "view 2 observed view 1's blur",
5805                "view 1 observed view 2's focus",
5806                "view 1 observed view 2's blur",
5807                "view 2 observed view 1's focus",
5808                "view 2 observed view 1's blur",
5809                "view 1 observed view 2's focus"
5810            ]
5811        );
5812
5813        view_1.update(cx, |_, cx| cx.focus(&view_1));
5814        assert!(!cx.is_child_focused(&view_1));
5815        assert!(!cx.is_child_focused(&view_2));
5816        assert_eq!(
5817            mem::take(&mut *view_events.lock()),
5818            ["view 2 blurred", "view 1 focused"],
5819        );
5820        assert_eq!(
5821            mem::take(&mut *observed_events.lock()),
5822            [
5823                "view 1 observed view 2's blur",
5824                "view 2 observed view 1's focus"
5825            ]
5826        );
5827
5828        view_1.update(cx, |_, cx| cx.focus(&view_2));
5829        assert_eq!(
5830            mem::take(&mut *view_events.lock()),
5831            ["view 1 blurred", "view 2 focused"],
5832        );
5833        assert_eq!(
5834            mem::take(&mut *observed_events.lock()),
5835            [
5836                "view 2 observed view 1's blur",
5837                "view 1 observed view 2's focus"
5838            ]
5839        );
5840
5841        view_1.update(cx, |_, _| drop(view_2));
5842        assert_eq!(mem::take(&mut *view_events.lock()), ["view 1 focused"]);
5843        assert_eq!(mem::take(&mut *observed_events.lock()), Vec::<&str>::new());
5844    }
5845
5846    #[crate::test(self)]
5847    fn test_deserialize_actions(cx: &mut AppContext) {
5848        #[derive(Clone, Debug, Deserialize, PartialEq, Eq)]
5849        pub struct ComplexAction {
5850            arg: String,
5851            count: usize,
5852        }
5853
5854        actions!(test::something, [SimpleAction]);
5855        impl_actions!(test::something, [ComplexAction]);
5856
5857        cx.add_global_action(move |_: &SimpleAction, _: &mut AppContext| {});
5858        cx.add_global_action(move |_: &ComplexAction, _: &mut AppContext| {});
5859
5860        let action1 = cx
5861            .deserialize_action(
5862                "test::something::ComplexAction",
5863                Some(r#"{"arg": "a", "count": 5}"#),
5864            )
5865            .unwrap();
5866        let action2 = cx
5867            .deserialize_action("test::something::SimpleAction", None)
5868            .unwrap();
5869        assert_eq!(
5870            action1.as_any().downcast_ref::<ComplexAction>().unwrap(),
5871            &ComplexAction {
5872                arg: "a".to_string(),
5873                count: 5,
5874            }
5875        );
5876        assert_eq!(
5877            action2.as_any().downcast_ref::<SimpleAction>().unwrap(),
5878            &SimpleAction
5879        );
5880    }
5881
5882    #[crate::test(self)]
5883    fn test_dispatch_action(cx: &mut AppContext) {
5884        struct ViewA {
5885            id: usize,
5886        }
5887
5888        impl Entity for ViewA {
5889            type Event = ();
5890        }
5891
5892        impl View for ViewA {
5893            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
5894                Empty::new().boxed()
5895            }
5896
5897            fn ui_name() -> &'static str {
5898                "View"
5899            }
5900        }
5901
5902        struct ViewB {
5903            id: usize,
5904        }
5905
5906        impl Entity for ViewB {
5907            type Event = ();
5908        }
5909
5910        impl View for ViewB {
5911            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
5912                Empty::new().boxed()
5913            }
5914
5915            fn ui_name() -> &'static str {
5916                "View"
5917            }
5918        }
5919
5920        #[derive(Clone, Default, Deserialize, PartialEq)]
5921        pub struct Action(pub String);
5922
5923        impl_actions!(test, [Action]);
5924
5925        let actions = Rc::new(RefCell::new(Vec::new()));
5926
5927        cx.add_global_action({
5928            let actions = actions.clone();
5929            move |_: &Action, _: &mut AppContext| {
5930                actions.borrow_mut().push("global".to_string());
5931            }
5932        });
5933
5934        cx.add_action({
5935            let actions = actions.clone();
5936            move |view: &mut ViewA, action: &Action, cx| {
5937                assert_eq!(action.0, "bar");
5938                cx.propagate_action();
5939                actions.borrow_mut().push(format!("{} a", view.id));
5940            }
5941        });
5942
5943        cx.add_action({
5944            let actions = actions.clone();
5945            move |view: &mut ViewA, _: &Action, cx| {
5946                if view.id != 1 {
5947                    cx.add_view(|cx| {
5948                        cx.propagate_action(); // Still works on a nested ViewContext
5949                        ViewB { id: 5 }
5950                    });
5951                }
5952                actions.borrow_mut().push(format!("{} b", view.id));
5953            }
5954        });
5955
5956        cx.add_action({
5957            let actions = actions.clone();
5958            move |view: &mut ViewB, _: &Action, cx| {
5959                cx.propagate_action();
5960                actions.borrow_mut().push(format!("{} c", view.id));
5961            }
5962        });
5963
5964        cx.add_action({
5965            let actions = actions.clone();
5966            move |view: &mut ViewB, _: &Action, cx| {
5967                cx.propagate_action();
5968                actions.borrow_mut().push(format!("{} d", view.id));
5969            }
5970        });
5971
5972        cx.capture_action({
5973            let actions = actions.clone();
5974            move |view: &mut ViewA, _: &Action, cx| {
5975                cx.propagate_action();
5976                actions.borrow_mut().push(format!("{} capture", view.id));
5977            }
5978        });
5979
5980        let observed_actions = Rc::new(RefCell::new(Vec::new()));
5981        cx.observe_actions({
5982            let observed_actions = observed_actions.clone();
5983            move |action_id, _| observed_actions.borrow_mut().push(action_id)
5984        })
5985        .detach();
5986
5987        let (window_id, view_1) = cx.add_window(Default::default(), |_| ViewA { id: 1 });
5988        let view_2 = cx.add_view(&view_1, |_| ViewB { id: 2 });
5989        let view_3 = cx.add_view(&view_2, |_| ViewA { id: 3 });
5990        let view_4 = cx.add_view(&view_3, |_| ViewB { id: 4 });
5991
5992        cx.handle_dispatch_action_from_effect(
5993            window_id,
5994            Some(view_4.id()),
5995            &Action("bar".to_string()),
5996        );
5997
5998        assert_eq!(
5999            *actions.borrow(),
6000            vec![
6001                "1 capture",
6002                "3 capture",
6003                "4 d",
6004                "4 c",
6005                "3 b",
6006                "3 a",
6007                "2 d",
6008                "2 c",
6009                "1 b"
6010            ]
6011        );
6012        assert_eq!(*observed_actions.borrow(), [Action::default().id()]);
6013
6014        // Remove view_1, which doesn't propagate the action
6015
6016        let (window_id, view_2) = cx.add_window(Default::default(), |_| ViewB { id: 2 });
6017        let view_3 = cx.add_view(&view_2, |_| ViewA { id: 3 });
6018        let view_4 = cx.add_view(&view_3, |_| ViewB { id: 4 });
6019
6020        actions.borrow_mut().clear();
6021        cx.handle_dispatch_action_from_effect(
6022            window_id,
6023            Some(view_4.id()),
6024            &Action("bar".to_string()),
6025        );
6026
6027        assert_eq!(
6028            *actions.borrow(),
6029            vec![
6030                "3 capture",
6031                "4 d",
6032                "4 c",
6033                "3 b",
6034                "3 a",
6035                "2 d",
6036                "2 c",
6037                "global"
6038            ]
6039        );
6040        assert_eq!(
6041            *observed_actions.borrow(),
6042            [Action::default().id(), Action::default().id()]
6043        );
6044    }
6045
6046    #[crate::test(self)]
6047    fn test_dispatch_keystroke(cx: &mut AppContext) {
6048        #[derive(Clone, Deserialize, PartialEq)]
6049        pub struct Action(String);
6050
6051        impl_actions!(test, [Action]);
6052
6053        struct View {
6054            id: usize,
6055            keymap_context: KeymapContext,
6056        }
6057
6058        impl Entity for View {
6059            type Event = ();
6060        }
6061
6062        impl super::View for View {
6063            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6064                Empty::new().boxed()
6065            }
6066
6067            fn ui_name() -> &'static str {
6068                "View"
6069            }
6070
6071            fn keymap_context(&self, _: &AppContext) -> KeymapContext {
6072                self.keymap_context.clone()
6073            }
6074        }
6075
6076        impl View {
6077            fn new(id: usize) -> Self {
6078                View {
6079                    id,
6080                    keymap_context: KeymapContext::default(),
6081                }
6082            }
6083        }
6084
6085        let mut view_1 = View::new(1);
6086        let mut view_2 = View::new(2);
6087        let mut view_3 = View::new(3);
6088        view_1.keymap_context.add_identifier("a");
6089        view_2.keymap_context.add_identifier("a");
6090        view_2.keymap_context.add_identifier("b");
6091        view_3.keymap_context.add_identifier("a");
6092        view_3.keymap_context.add_identifier("b");
6093        view_3.keymap_context.add_identifier("c");
6094
6095        let (window_id, view_1) = cx.add_window(Default::default(), |_| view_1);
6096        let view_2 = cx.add_view(&view_1, |_| view_2);
6097        let _view_3 = cx.add_view(&view_2, |cx| {
6098            cx.focus_self();
6099            view_3
6100        });
6101
6102        // This binding only dispatches an action on view 2 because that view will have
6103        // "a" and "b" in its context, but not "c".
6104        cx.add_bindings(vec![Binding::new(
6105            "a",
6106            Action("a".to_string()),
6107            Some("a && b && !c"),
6108        )]);
6109
6110        cx.add_bindings(vec![Binding::new("b", Action("b".to_string()), None)]);
6111
6112        // This binding only dispatches an action on views 2 and 3, because they have
6113        // a parent view with a in its context
6114        cx.add_bindings(vec![Binding::new(
6115            "c",
6116            Action("c".to_string()),
6117            Some("b > c"),
6118        )]);
6119
6120        // This binding only dispatches an action on view 2, because they have
6121        // a parent view with a in its context
6122        cx.add_bindings(vec![Binding::new(
6123            "d",
6124            Action("d".to_string()),
6125            Some("a && !b > b"),
6126        )]);
6127
6128        let actions = Rc::new(RefCell::new(Vec::new()));
6129        cx.add_action({
6130            let actions = actions.clone();
6131            move |view: &mut View, action: &Action, cx| {
6132                actions
6133                    .borrow_mut()
6134                    .push(format!("{} {}", view.id, action.0));
6135
6136                if action.0 == "b" {
6137                    cx.propagate_action();
6138                }
6139            }
6140        });
6141
6142        cx.add_global_action({
6143            let actions = actions.clone();
6144            move |action: &Action, _| {
6145                actions.borrow_mut().push(format!("global {}", action.0));
6146            }
6147        });
6148
6149        cx.update_window(window_id, |cx| {
6150            cx.dispatch_keystroke(&Keystroke::parse("a").unwrap())
6151        });
6152        assert_eq!(&*actions.borrow(), &["2 a"]);
6153        actions.borrow_mut().clear();
6154
6155        cx.update_window(window_id, |cx| {
6156            cx.dispatch_keystroke(&Keystroke::parse("b").unwrap());
6157        });
6158
6159        assert_eq!(&*actions.borrow(), &["3 b", "2 b", "1 b", "global b"]);
6160        actions.borrow_mut().clear();
6161
6162        cx.update_window(window_id, |cx| {
6163            cx.dispatch_keystroke(&Keystroke::parse("c").unwrap());
6164        });
6165        assert_eq!(&*actions.borrow(), &["3 c"]);
6166        actions.borrow_mut().clear();
6167
6168        cx.update_window(window_id, |cx| {
6169            cx.dispatch_keystroke(&Keystroke::parse("d").unwrap());
6170        });
6171        assert_eq!(&*actions.borrow(), &["2 d"]);
6172        actions.borrow_mut().clear();
6173    }
6174
6175    #[crate::test(self)]
6176    fn test_keystrokes_for_action(cx: &mut AppContext) {
6177        actions!(test, [Action1, Action2, GlobalAction]);
6178
6179        struct View1 {}
6180        struct View2 {}
6181
6182        impl Entity for View1 {
6183            type Event = ();
6184        }
6185        impl Entity for View2 {
6186            type Event = ();
6187        }
6188
6189        impl super::View for View1 {
6190            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6191                Empty::new().boxed()
6192            }
6193            fn ui_name() -> &'static str {
6194                "View1"
6195            }
6196        }
6197        impl super::View for View2 {
6198            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6199                Empty::new().boxed()
6200            }
6201            fn ui_name() -> &'static str {
6202                "View2"
6203            }
6204        }
6205
6206        let (window_id, view_1) = cx.add_window(Default::default(), |_| View1 {});
6207        let view_2 = cx.add_view(&view_1, |cx| {
6208            cx.focus_self();
6209            View2 {}
6210        });
6211
6212        cx.add_action(|_: &mut View1, _: &Action1, _cx| {});
6213        cx.add_action(|_: &mut View2, _: &Action2, _cx| {});
6214        cx.add_global_action(|_: &GlobalAction, _| {});
6215
6216        cx.add_bindings(vec![
6217            Binding::new("a", Action1, Some("View1")),
6218            Binding::new("b", Action2, Some("View1 > View2")),
6219            Binding::new("c", GlobalAction, Some("View3")), // View 3 does not exist
6220        ]);
6221
6222        // Sanity check
6223        assert_eq!(
6224            cx.keystrokes_for_action(window_id, view_1.id(), &Action1)
6225                .unwrap()
6226                .as_slice(),
6227            &[Keystroke::parse("a").unwrap()]
6228        );
6229        assert_eq!(
6230            cx.keystrokes_for_action(window_id, view_2.id(), &Action2)
6231                .unwrap()
6232                .as_slice(),
6233            &[Keystroke::parse("b").unwrap()]
6234        );
6235
6236        // The 'a' keystroke propagates up the view tree from view_2
6237        // to view_1. The action, Action1, is handled by view_1.
6238        assert_eq!(
6239            cx.keystrokes_for_action(window_id, view_2.id(), &Action1)
6240                .unwrap()
6241                .as_slice(),
6242            &[Keystroke::parse("a").unwrap()]
6243        );
6244
6245        // Actions that are handled below the current view don't have bindings
6246        assert_eq!(
6247            cx.keystrokes_for_action(window_id, view_1.id(), &Action2),
6248            None
6249        );
6250
6251        // Actions that are handled in other branches of the tree should not have a binding
6252        assert_eq!(
6253            cx.keystrokes_for_action(window_id, view_2.id(), &GlobalAction),
6254            None
6255        );
6256
6257        // Produces a list of actions and key bindings
6258        fn available_actions(
6259            window_id: usize,
6260            view_id: usize,
6261            cx: &mut AppContext,
6262        ) -> Vec<(&'static str, Vec<Keystroke>)> {
6263            cx.available_actions(window_id, view_id)
6264                .map(|(action_name, _, bindings)| {
6265                    (
6266                        action_name,
6267                        bindings
6268                            .iter()
6269                            .map(|binding| binding.keystrokes()[0].clone())
6270                            .collect::<Vec<_>>(),
6271                    )
6272                })
6273                .sorted_by(|(name1, _), (name2, _)| name1.cmp(name2))
6274                .collect()
6275        }
6276
6277        // Check that global actions do not have a binding, even if a binding does exist in another view
6278        assert_eq!(
6279            &available_actions(window_id, view_1.id(), cx),
6280            &[
6281                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
6282                ("test::GlobalAction", vec![])
6283            ],
6284        );
6285
6286        // Check that view 1 actions and bindings are available even when called from view 2
6287        assert_eq!(
6288            &available_actions(window_id, view_2.id(), cx),
6289            &[
6290                ("test::Action1", vec![Keystroke::parse("a").unwrap()]),
6291                ("test::Action2", vec![Keystroke::parse("b").unwrap()]),
6292                ("test::GlobalAction", vec![]),
6293            ],
6294        );
6295    }
6296
6297    #[crate::test(self)]
6298    async fn test_model_condition(cx: &mut TestAppContext) {
6299        struct Counter(usize);
6300
6301        impl super::Entity for Counter {
6302            type Event = ();
6303        }
6304
6305        impl Counter {
6306            fn inc(&mut self, cx: &mut ModelContext<Self>) {
6307                self.0 += 1;
6308                cx.notify();
6309            }
6310        }
6311
6312        let model = cx.add_model(|_| Counter(0));
6313
6314        let condition1 = model.condition(cx, |model, _| model.0 == 2);
6315        let condition2 = model.condition(cx, |model, _| model.0 == 3);
6316        smol::pin!(condition1, condition2);
6317
6318        model.update(cx, |model, cx| model.inc(cx));
6319        assert_eq!(poll_once(&mut condition1).await, None);
6320        assert_eq!(poll_once(&mut condition2).await, None);
6321
6322        model.update(cx, |model, cx| model.inc(cx));
6323        assert_eq!(poll_once(&mut condition1).await, Some(()));
6324        assert_eq!(poll_once(&mut condition2).await, None);
6325
6326        model.update(cx, |model, cx| model.inc(cx));
6327        assert_eq!(poll_once(&mut condition2).await, Some(()));
6328
6329        model.update(cx, |_, cx| cx.notify());
6330    }
6331
6332    #[crate::test(self)]
6333    #[should_panic]
6334    async fn test_model_condition_timeout(cx: &mut TestAppContext) {
6335        struct Model;
6336
6337        impl super::Entity for Model {
6338            type Event = ();
6339        }
6340
6341        let model = cx.add_model(|_| Model);
6342        model.condition(cx, |_, _| false).await;
6343    }
6344
6345    #[crate::test(self)]
6346    #[should_panic(expected = "model dropped with pending condition")]
6347    async fn test_model_condition_panic_on_drop(cx: &mut TestAppContext) {
6348        struct Model;
6349
6350        impl super::Entity for Model {
6351            type Event = ();
6352        }
6353
6354        let model = cx.add_model(|_| Model);
6355        let condition = model.condition(cx, |_, _| false);
6356        cx.update(|_| drop(model));
6357        condition.await;
6358    }
6359
6360    #[crate::test(self)]
6361    async fn test_view_condition(cx: &mut TestAppContext) {
6362        struct Counter(usize);
6363
6364        impl super::Entity for Counter {
6365            type Event = ();
6366        }
6367
6368        impl super::View for Counter {
6369            fn ui_name() -> &'static str {
6370                "test view"
6371            }
6372
6373            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6374                Empty::new().boxed()
6375            }
6376        }
6377
6378        impl Counter {
6379            fn inc(&mut self, cx: &mut ViewContext<Self>) {
6380                self.0 += 1;
6381                cx.notify();
6382            }
6383        }
6384
6385        let (_, view) = cx.add_window(|_| Counter(0));
6386
6387        let condition1 = view.condition(cx, |view, _| view.0 == 2);
6388        let condition2 = view.condition(cx, |view, _| view.0 == 3);
6389        smol::pin!(condition1, condition2);
6390
6391        view.update(cx, |view, cx| view.inc(cx));
6392        assert_eq!(poll_once(&mut condition1).await, None);
6393        assert_eq!(poll_once(&mut condition2).await, None);
6394
6395        view.update(cx, |view, cx| view.inc(cx));
6396        assert_eq!(poll_once(&mut condition1).await, Some(()));
6397        assert_eq!(poll_once(&mut condition2).await, None);
6398
6399        view.update(cx, |view, cx| view.inc(cx));
6400        assert_eq!(poll_once(&mut condition2).await, Some(()));
6401        view.update(cx, |_, cx| cx.notify());
6402    }
6403
6404    #[crate::test(self)]
6405    #[should_panic]
6406    async fn test_view_condition_timeout(cx: &mut TestAppContext) {
6407        let (_, view) = cx.add_window(|_| TestView::default());
6408        view.condition(cx, |_, _| false).await;
6409    }
6410
6411    #[crate::test(self)]
6412    #[should_panic(expected = "view dropped with pending condition")]
6413    async fn test_view_condition_panic_on_drop(cx: &mut TestAppContext) {
6414        let (_, root_view) = cx.add_window(|_| TestView::default());
6415        let view = cx.add_view(&root_view, |_| TestView::default());
6416
6417        let condition = view.condition(cx, |_, _| false);
6418        cx.update(|_| drop(view));
6419        condition.await;
6420    }
6421
6422    #[crate::test(self)]
6423    fn test_refresh_windows(cx: &mut AppContext) {
6424        struct View(usize);
6425
6426        impl super::Entity for View {
6427            type Event = ();
6428        }
6429
6430        impl super::View for View {
6431            fn ui_name() -> &'static str {
6432                "test view"
6433            }
6434
6435            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6436                Empty::new().named(format!("render count: {}", post_inc(&mut self.0)))
6437            }
6438        }
6439
6440        let (window_id, root_view) = cx.add_window(Default::default(), |_| View(0));
6441        cx.update_window(window_id, |cx| {
6442            assert_eq!(
6443                cx.window.rendered_views[&root_view.id()].name(),
6444                Some("render count: 0")
6445            );
6446        });
6447
6448        let view = cx.add_view(&root_view, |cx| {
6449            cx.refresh_windows();
6450            View(0)
6451        });
6452
6453        cx.update_window(window_id, |cx| {
6454            assert_eq!(
6455                cx.window.rendered_views[&root_view.id()].name(),
6456                Some("render count: 1")
6457            );
6458            assert_eq!(
6459                cx.window.rendered_views[&view.id()].name(),
6460                Some("render count: 0")
6461            );
6462        });
6463
6464        cx.update(|cx| cx.refresh_windows());
6465
6466        cx.update_window(window_id, |cx| {
6467            assert_eq!(
6468                cx.window.rendered_views[&root_view.id()].name(),
6469                Some("render count: 2")
6470            );
6471            assert_eq!(
6472                cx.window.rendered_views[&view.id()].name(),
6473                Some("render count: 1")
6474            );
6475        });
6476
6477        cx.update(|cx| {
6478            cx.refresh_windows();
6479            drop(view);
6480        });
6481
6482        cx.update_window(window_id, |cx| {
6483            assert_eq!(
6484                cx.window.rendered_views[&root_view.id()].name(),
6485                Some("render count: 3")
6486            );
6487            assert_eq!(cx.window.rendered_views.len(), 1);
6488        });
6489    }
6490
6491    #[crate::test(self)]
6492    async fn test_labeled_tasks(cx: &mut TestAppContext) {
6493        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6494        let (mut sender, mut reciever) = postage::oneshot::channel::<()>();
6495        let task = cx
6496            .update(|cx| cx.spawn_labeled("Test Label", |_| async move { reciever.recv().await }));
6497
6498        assert_eq!(
6499            Some("Test Label"),
6500            cx.update(|cx| cx.active_labeled_tasks().next())
6501        );
6502        sender
6503            .send(())
6504            .await
6505            .expect("Could not send message to complete task");
6506        task.await;
6507
6508        assert_eq!(None, cx.update(|cx| cx.active_labeled_tasks().next()));
6509    }
6510
6511    #[crate::test(self)]
6512    async fn test_window_activation(cx: &mut TestAppContext) {
6513        struct View(&'static str);
6514
6515        impl super::Entity for View {
6516            type Event = ();
6517        }
6518
6519        impl super::View for View {
6520            fn ui_name() -> &'static str {
6521                "test view"
6522            }
6523
6524            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6525                Empty::new().boxed()
6526            }
6527        }
6528
6529        let events = Rc::new(RefCell::new(Vec::new()));
6530        let (window_1, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6531            cx.observe_window_activation({
6532                let events = events.clone();
6533                move |this, active, _| events.borrow_mut().push((this.0, active))
6534            })
6535            .detach();
6536            View("window 1")
6537        });
6538        assert_eq!(mem::take(&mut *events.borrow_mut()), [("window 1", true)]);
6539
6540        let (window_2, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6541            cx.observe_window_activation({
6542                let events = events.clone();
6543                move |this, active, _| events.borrow_mut().push((this.0, active))
6544            })
6545            .detach();
6546            View("window 2")
6547        });
6548        assert_eq!(
6549            mem::take(&mut *events.borrow_mut()),
6550            [("window 1", false), ("window 2", true)]
6551        );
6552
6553        let (window_3, _) = cx.add_window(|cx: &mut ViewContext<View>| {
6554            cx.observe_window_activation({
6555                let events = events.clone();
6556                move |this, active, _| events.borrow_mut().push((this.0, active))
6557            })
6558            .detach();
6559            View("window 3")
6560        });
6561        assert_eq!(
6562            mem::take(&mut *events.borrow_mut()),
6563            [("window 2", false), ("window 3", true)]
6564        );
6565
6566        cx.simulate_window_activation(Some(window_2));
6567        assert_eq!(
6568            mem::take(&mut *events.borrow_mut()),
6569            [("window 3", false), ("window 2", true)]
6570        );
6571
6572        cx.simulate_window_activation(Some(window_1));
6573        assert_eq!(
6574            mem::take(&mut *events.borrow_mut()),
6575            [("window 2", false), ("window 1", true)]
6576        );
6577
6578        cx.simulate_window_activation(Some(window_3));
6579        assert_eq!(
6580            mem::take(&mut *events.borrow_mut()),
6581            [("window 1", false), ("window 3", true)]
6582        );
6583
6584        cx.simulate_window_activation(Some(window_3));
6585        assert_eq!(mem::take(&mut *events.borrow_mut()), []);
6586    }
6587
6588    #[crate::test(self)]
6589    fn test_child_view(cx: &mut AppContext) {
6590        struct Child {
6591            rendered: Rc<Cell<bool>>,
6592            dropped: Rc<Cell<bool>>,
6593        }
6594
6595        impl super::Entity for Child {
6596            type Event = ();
6597        }
6598
6599        impl super::View for Child {
6600            fn ui_name() -> &'static str {
6601                "child view"
6602            }
6603
6604            fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6605                self.rendered.set(true);
6606                Empty::new().boxed()
6607            }
6608        }
6609
6610        impl Drop for Child {
6611            fn drop(&mut self) {
6612                self.dropped.set(true);
6613            }
6614        }
6615
6616        struct Parent {
6617            child: Option<ViewHandle<Child>>,
6618        }
6619
6620        impl super::Entity for Parent {
6621            type Event = ();
6622        }
6623
6624        impl super::View for Parent {
6625            fn ui_name() -> &'static str {
6626                "parent view"
6627            }
6628
6629            fn render(&mut self, cx: &mut ViewContext<Self>) -> Element<Self> {
6630                if let Some(child) = self.child.as_ref() {
6631                    ChildView::new(child, cx).boxed()
6632                } else {
6633                    Empty::new().boxed()
6634                }
6635            }
6636        }
6637
6638        let child_rendered = Rc::new(Cell::new(false));
6639        let child_dropped = Rc::new(Cell::new(false));
6640        let (_, root_view) = cx.add_window(Default::default(), |cx| Parent {
6641            child: Some(cx.add_view(|_| Child {
6642                rendered: child_rendered.clone(),
6643                dropped: child_dropped.clone(),
6644            })),
6645        });
6646        assert!(child_rendered.take());
6647        assert!(!child_dropped.take());
6648
6649        root_view.update(cx, |view, cx| {
6650            view.child.take();
6651            cx.notify();
6652        });
6653        assert!(!child_rendered.take());
6654        assert!(child_dropped.take());
6655    }
6656
6657    #[derive(Default)]
6658    struct TestView {
6659        events: Vec<String>,
6660    }
6661
6662    impl Entity for TestView {
6663        type Event = String;
6664    }
6665
6666    impl View for TestView {
6667        fn ui_name() -> &'static str {
6668            "TestView"
6669        }
6670
6671        fn render(&mut self, _: &mut ViewContext<Self>) -> Element<Self> {
6672            Empty::new().boxed()
6673        }
6674    }
6675}