app.rs

   1use std::{
   2    any::{TypeId, type_name},
   3    cell::{BorrowMutError, Ref, RefCell, RefMut},
   4    marker::PhantomData,
   5    mem,
   6    ops::{Deref, DerefMut},
   7    path::{Path, PathBuf},
   8    rc::{Rc, Weak},
   9    sync::{Arc, atomic::Ordering::SeqCst},
  10    time::Duration,
  11};
  12
  13use anyhow::{Context as _, Result, anyhow};
  14use derive_more::{Deref, DerefMut};
  15use futures::{
  16    Future, FutureExt,
  17    channel::oneshot,
  18    future::{LocalBoxFuture, Shared},
  19};
  20use parking_lot::RwLock;
  21use slotmap::SlotMap;
  22
  23pub use async_context::*;
  24use collections::{FxHashMap, FxHashSet, HashMap, VecDeque};
  25pub use context::*;
  26pub use entity_map::*;
  27use http_client::{HttpClient, Url};
  28use smallvec::SmallVec;
  29#[cfg(any(test, feature = "test-support"))]
  30pub use test_context::*;
  31use util::{ResultExt, debug_panic};
  32
  33#[cfg(any(feature = "inspector", debug_assertions))]
  34use crate::InspectorElementRegistry;
  35use crate::{
  36    Action, ActionBuildError, ActionRegistry, Any, AnyView, AnyWindowHandle, AppContext, Asset,
  37    AssetSource, BackgroundExecutor, Bounds, ClipboardItem, CursorStyle, DispatchPhase, DisplayId,
  38    EventEmitter, FocusHandle, FocusMap, ForegroundExecutor, Global, KeyBinding, KeyContext,
  39    Keymap, Keystroke, LayoutId, Menu, MenuItem, OwnedMenu, PathPromptOptions, Pixels, Platform,
  40    PlatformDisplay, PlatformKeyboardLayout, PlatformKeyboardMapper, Point, PromptBuilder,
  41    PromptButton, PromptHandle, PromptLevel, Render, RenderImage, RenderablePromptHandle,
  42    Reservation, ScreenCaptureSource, SubscriberSet, Subscription, SvgRenderer, Task, TextSystem,
  43    Window, WindowAppearance, WindowHandle, WindowId, WindowInvalidator,
  44    colors::{Colors, GlobalColors},
  45    current_platform, hash, init_app_menus,
  46};
  47
  48mod async_context;
  49mod context;
  50mod entity_map;
  51#[cfg(any(test, feature = "test-support"))]
  52mod test_context;
  53
  54/// The duration for which futures returned from [Context::on_app_quit] can run before the application fully quits.
  55pub const SHUTDOWN_TIMEOUT: Duration = Duration::from_millis(100);
  56
  57/// Temporary(?) wrapper around [`RefCell<App>`] to help us debug any double borrows.
  58/// Strongly consider removing after stabilization.
  59#[doc(hidden)]
  60pub struct AppCell {
  61    app: RefCell<App>,
  62}
  63
  64impl AppCell {
  65    #[doc(hidden)]
  66    #[track_caller]
  67    pub fn borrow(&self) -> AppRef<'_> {
  68        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  69            let thread_id = std::thread::current().id();
  70            eprintln!("borrowed {thread_id:?}");
  71        }
  72        AppRef(self.app.borrow())
  73    }
  74
  75    #[doc(hidden)]
  76    #[track_caller]
  77    pub fn borrow_mut(&self) -> AppRefMut<'_> {
  78        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  79            let thread_id = std::thread::current().id();
  80            eprintln!("borrowed {thread_id:?}");
  81        }
  82        AppRefMut(self.app.borrow_mut())
  83    }
  84
  85    #[doc(hidden)]
  86    #[track_caller]
  87    pub fn try_borrow_mut(&self) -> Result<AppRefMut<'_>, BorrowMutError> {
  88        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  89            let thread_id = std::thread::current().id();
  90            eprintln!("borrowed {thread_id:?}");
  91        }
  92        Ok(AppRefMut(self.app.try_borrow_mut()?))
  93    }
  94}
  95
  96#[doc(hidden)]
  97#[derive(Deref, DerefMut)]
  98pub struct AppRef<'a>(Ref<'a, App>);
  99
 100impl Drop for AppRef<'_> {
 101    fn drop(&mut self) {
 102        if option_env!("TRACK_THREAD_BORROWS").is_some() {
 103            let thread_id = std::thread::current().id();
 104            eprintln!("dropped borrow from {thread_id:?}");
 105        }
 106    }
 107}
 108
 109#[doc(hidden)]
 110#[derive(Deref, DerefMut)]
 111pub struct AppRefMut<'a>(RefMut<'a, App>);
 112
 113impl Drop for AppRefMut<'_> {
 114    fn drop(&mut self) {
 115        if option_env!("TRACK_THREAD_BORROWS").is_some() {
 116            let thread_id = std::thread::current().id();
 117            eprintln!("dropped {thread_id:?}");
 118        }
 119    }
 120}
 121
 122/// A reference to a GPUI application, typically constructed in the `main` function of your app.
 123/// You won't interact with this type much outside of initial configuration and startup.
 124pub struct Application(Rc<AppCell>);
 125
 126/// Represents an application before it is fully launched. Once your app is
 127/// configured, you'll start the app with `App::run`.
 128impl Application {
 129    /// Builds an app with the given asset source.
 130    #[allow(clippy::new_without_default)]
 131    pub fn new() -> Self {
 132        #[cfg(any(test, feature = "test-support"))]
 133        log::info!("GPUI was compiled in test mode");
 134
 135        Self(App::new_app(
 136            current_platform(false),
 137            Arc::new(()),
 138            Arc::new(NullHttpClient),
 139        ))
 140    }
 141
 142    /// Build an app in headless mode. This prevents opening windows,
 143    /// but makes it possible to run an application in an context like
 144    /// SSH, where GUI applications are not allowed.
 145    pub fn headless() -> Self {
 146        Self(App::new_app(
 147            current_platform(true),
 148            Arc::new(()),
 149            Arc::new(NullHttpClient),
 150        ))
 151    }
 152
 153    /// Assign
 154    pub fn with_assets(self, asset_source: impl AssetSource) -> Self {
 155        let mut context_lock = self.0.borrow_mut();
 156        let asset_source = Arc::new(asset_source);
 157        context_lock.asset_source = asset_source.clone();
 158        context_lock.svg_renderer = SvgRenderer::new(asset_source);
 159        drop(context_lock);
 160        self
 161    }
 162
 163    /// Sets the HTTP client for the application.
 164    pub fn with_http_client(self, http_client: Arc<dyn HttpClient>) -> Self {
 165        let mut context_lock = self.0.borrow_mut();
 166        context_lock.http_client = http_client;
 167        drop(context_lock);
 168        self
 169    }
 170
 171    /// Start the application. The provided callback will be called once the
 172    /// app is fully launched.
 173    pub fn run<F>(self, on_finish_launching: F)
 174    where
 175        F: 'static + FnOnce(&mut App),
 176    {
 177        let this = self.0.clone();
 178        let platform = self.0.borrow().platform.clone();
 179        platform.run(Box::new(move || {
 180            let cx = &mut *this.borrow_mut();
 181            on_finish_launching(cx);
 182        }));
 183    }
 184
 185    /// Register a handler to be invoked when the platform instructs the application
 186    /// to open one or more URLs.
 187    pub fn on_open_urls<F>(&self, mut callback: F) -> &Self
 188    where
 189        F: 'static + FnMut(Vec<String>),
 190    {
 191        self.0.borrow().platform.on_open_urls(Box::new(callback));
 192        self
 193    }
 194
 195    /// Invokes a handler when an already-running application is launched.
 196    /// On macOS, this can occur when the application icon is double-clicked or the app is launched via the dock.
 197    pub fn on_reopen<F>(&self, mut callback: F) -> &Self
 198    where
 199        F: 'static + FnMut(&mut App),
 200    {
 201        let this = Rc::downgrade(&self.0);
 202        self.0.borrow_mut().platform.on_reopen(Box::new(move || {
 203            if let Some(app) = this.upgrade() {
 204                callback(&mut app.borrow_mut());
 205            }
 206        }));
 207        self
 208    }
 209
 210    /// Returns a handle to the [`BackgroundExecutor`] associated with this app, which can be used to spawn futures in the background.
 211    pub fn background_executor(&self) -> BackgroundExecutor {
 212        self.0.borrow().background_executor.clone()
 213    }
 214
 215    /// Returns a handle to the [`ForegroundExecutor`] associated with this app, which can be used to spawn futures in the foreground.
 216    pub fn foreground_executor(&self) -> ForegroundExecutor {
 217        self.0.borrow().foreground_executor.clone()
 218    }
 219
 220    /// Returns a reference to the [`TextSystem`] associated with this app.
 221    pub fn text_system(&self) -> Arc<TextSystem> {
 222        self.0.borrow().text_system.clone()
 223    }
 224
 225    /// Returns the file URL of the executable with the specified name in the application bundle
 226    pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
 227        self.0.borrow().path_for_auxiliary_executable(name)
 228    }
 229}
 230
 231type Handler = Box<dyn FnMut(&mut App) -> bool + 'static>;
 232type Listener = Box<dyn FnMut(&dyn Any, &mut App) -> bool + 'static>;
 233pub(crate) type KeystrokeObserver =
 234    Box<dyn FnMut(&KeystrokeEvent, &mut Window, &mut App) -> bool + 'static>;
 235type QuitHandler = Box<dyn FnOnce(&mut App) -> LocalBoxFuture<'static, ()> + 'static>;
 236type WindowClosedHandler = Box<dyn FnMut(&mut App)>;
 237type ReleaseListener = Box<dyn FnOnce(&mut dyn Any, &mut App) + 'static>;
 238type NewEntityListener = Box<dyn FnMut(AnyEntity, &mut Option<&mut Window>, &mut App) + 'static>;
 239
 240/// Contains the state of the full application, and passed as a reference to a variety of callbacks.
 241/// Other [Context] derefs to this type.
 242/// You need a reference to an `App` to access the state of a [Entity].
 243pub struct App {
 244    pub(crate) this: Weak<AppCell>,
 245    pub(crate) platform: Rc<dyn Platform>,
 246    text_system: Arc<TextSystem>,
 247    flushing_effects: bool,
 248    pending_updates: usize,
 249    pub(crate) actions: Rc<ActionRegistry>,
 250    pub(crate) active_drag: Option<AnyDrag>,
 251    pub(crate) background_executor: BackgroundExecutor,
 252    pub(crate) foreground_executor: ForegroundExecutor,
 253    pub(crate) loading_assets: FxHashMap<(TypeId, u64), Box<dyn Any>>,
 254    asset_source: Arc<dyn AssetSource>,
 255    pub(crate) svg_renderer: SvgRenderer,
 256    http_client: Arc<dyn HttpClient>,
 257    pub(crate) globals_by_type: FxHashMap<TypeId, Box<dyn Any>>,
 258    pub(crate) entities: EntityMap,
 259    pub(crate) window_update_stack: Vec<WindowId>,
 260    pub(crate) new_entity_observers: SubscriberSet<TypeId, NewEntityListener>,
 261    pub(crate) windows: SlotMap<WindowId, Option<Window>>,
 262    pub(crate) window_handles: FxHashMap<WindowId, AnyWindowHandle>,
 263    pub(crate) focus_handles: Arc<FocusMap>,
 264    pub(crate) keymap: Rc<RefCell<Keymap>>,
 265    pub(crate) keyboard_layout: Box<dyn PlatformKeyboardLayout>,
 266    pub(crate) keyboard_mapper: Rc<dyn PlatformKeyboardMapper>,
 267    pub(crate) global_action_listeners:
 268        FxHashMap<TypeId, Vec<Rc<dyn Fn(&dyn Any, DispatchPhase, &mut Self)>>>,
 269    pending_effects: VecDeque<Effect>,
 270    pub(crate) pending_notifications: FxHashSet<EntityId>,
 271    pub(crate) pending_global_notifications: FxHashSet<TypeId>,
 272    pub(crate) observers: SubscriberSet<EntityId, Handler>,
 273    // TypeId is the type of the event that the listener callback expects
 274    pub(crate) event_listeners: SubscriberSet<EntityId, (TypeId, Listener)>,
 275    pub(crate) keystroke_observers: SubscriberSet<(), KeystrokeObserver>,
 276    pub(crate) keystroke_interceptors: SubscriberSet<(), KeystrokeObserver>,
 277    pub(crate) keyboard_layout_observers: SubscriberSet<(), Handler>,
 278    pub(crate) release_listeners: SubscriberSet<EntityId, ReleaseListener>,
 279    pub(crate) global_observers: SubscriberSet<TypeId, Handler>,
 280    pub(crate) quit_observers: SubscriberSet<(), QuitHandler>,
 281    pub(crate) restart_observers: SubscriberSet<(), Handler>,
 282    pub(crate) restart_path: Option<PathBuf>,
 283    pub(crate) window_closed_observers: SubscriberSet<(), WindowClosedHandler>,
 284    pub(crate) layout_id_buffer: Vec<LayoutId>, // We recycle this memory across layout requests.
 285    pub(crate) propagate_event: bool,
 286    pub(crate) prompt_builder: Option<PromptBuilder>,
 287    pub(crate) window_invalidators_by_entity:
 288        FxHashMap<EntityId, FxHashMap<WindowId, WindowInvalidator>>,
 289    pub(crate) tracked_entities: FxHashMap<WindowId, FxHashSet<EntityId>>,
 290    #[cfg(any(feature = "inspector", debug_assertions))]
 291    pub(crate) inspector_renderer: Option<crate::InspectorRenderer>,
 292    #[cfg(any(feature = "inspector", debug_assertions))]
 293    pub(crate) inspector_element_registry: InspectorElementRegistry,
 294    #[cfg(any(test, feature = "test-support", debug_assertions))]
 295    pub(crate) name: Option<&'static str>,
 296    quitting: bool,
 297}
 298
 299impl App {
 300    #[allow(clippy::new_ret_no_self)]
 301    pub(crate) fn new_app(
 302        platform: Rc<dyn Platform>,
 303        asset_source: Arc<dyn AssetSource>,
 304        http_client: Arc<dyn HttpClient>,
 305    ) -> Rc<AppCell> {
 306        let executor = platform.background_executor();
 307        let foreground_executor = platform.foreground_executor();
 308        assert!(
 309            executor.is_main_thread(),
 310            "must construct App on main thread"
 311        );
 312
 313        let text_system = Arc::new(TextSystem::new(platform.text_system()));
 314        let entities = EntityMap::new();
 315        let keyboard_layout = platform.keyboard_layout();
 316        let keyboard_mapper = platform.keyboard_mapper();
 317
 318        let app = Rc::new_cyclic(|this| AppCell {
 319            app: RefCell::new(App {
 320                this: this.clone(),
 321                platform: platform.clone(),
 322                text_system,
 323                actions: Rc::new(ActionRegistry::default()),
 324                flushing_effects: false,
 325                pending_updates: 0,
 326                active_drag: None,
 327                background_executor: executor,
 328                foreground_executor,
 329                svg_renderer: SvgRenderer::new(asset_source.clone()),
 330                loading_assets: Default::default(),
 331                asset_source,
 332                http_client,
 333                globals_by_type: FxHashMap::default(),
 334                entities,
 335                new_entity_observers: SubscriberSet::new(),
 336                windows: SlotMap::with_key(),
 337                window_update_stack: Vec::new(),
 338                window_handles: FxHashMap::default(),
 339                focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 340                keymap: Rc::new(RefCell::new(Keymap::default())),
 341                keyboard_layout,
 342                keyboard_mapper,
 343                global_action_listeners: FxHashMap::default(),
 344                pending_effects: VecDeque::new(),
 345                pending_notifications: FxHashSet::default(),
 346                pending_global_notifications: FxHashSet::default(),
 347                observers: SubscriberSet::new(),
 348                tracked_entities: FxHashMap::default(),
 349                window_invalidators_by_entity: FxHashMap::default(),
 350                event_listeners: SubscriberSet::new(),
 351                release_listeners: SubscriberSet::new(),
 352                keystroke_observers: SubscriberSet::new(),
 353                keystroke_interceptors: SubscriberSet::new(),
 354                keyboard_layout_observers: SubscriberSet::new(),
 355                global_observers: SubscriberSet::new(),
 356                quit_observers: SubscriberSet::new(),
 357                restart_observers: SubscriberSet::new(),
 358                restart_path: None,
 359                window_closed_observers: SubscriberSet::new(),
 360                layout_id_buffer: Default::default(),
 361                propagate_event: true,
 362                prompt_builder: Some(PromptBuilder::Default),
 363                #[cfg(any(feature = "inspector", debug_assertions))]
 364                inspector_renderer: None,
 365                #[cfg(any(feature = "inspector", debug_assertions))]
 366                inspector_element_registry: InspectorElementRegistry::default(),
 367                quitting: false,
 368
 369                #[cfg(any(test, feature = "test-support", debug_assertions))]
 370                name: None,
 371            }),
 372        });
 373
 374        init_app_menus(platform.as_ref(), &app.borrow());
 375
 376        platform.on_keyboard_layout_change(Box::new({
 377            let app = Rc::downgrade(&app);
 378            move || {
 379                if let Some(app) = app.upgrade() {
 380                    let cx = &mut app.borrow_mut();
 381                    cx.keyboard_layout = cx.platform.keyboard_layout();
 382                    cx.keyboard_mapper = cx.platform.keyboard_mapper();
 383                    cx.keyboard_layout_observers
 384                        .clone()
 385                        .retain(&(), move |callback| (callback)(cx));
 386                }
 387            }
 388        }));
 389
 390        platform.on_quit(Box::new({
 391            let cx = app.clone();
 392            move || {
 393                cx.borrow_mut().shutdown();
 394            }
 395        }));
 396
 397        app
 398    }
 399
 400    /// Quit the application gracefully. Handlers registered with [`Context::on_app_quit`]
 401    /// will be given 100ms to complete before exiting.
 402    pub fn shutdown(&mut self) {
 403        let mut futures = Vec::new();
 404
 405        for observer in self.quit_observers.remove(&()) {
 406            futures.push(observer(self));
 407        }
 408
 409        self.windows.clear();
 410        self.window_handles.clear();
 411        self.flush_effects();
 412        self.quitting = true;
 413
 414        let futures = futures::future::join_all(futures);
 415        if self
 416            .background_executor
 417            .block_with_timeout(SHUTDOWN_TIMEOUT, futures)
 418            .is_err()
 419        {
 420            log::error!("timed out waiting on app_will_quit");
 421        }
 422
 423        self.quitting = false;
 424    }
 425
 426    /// Get the id of the current keyboard layout
 427    pub fn keyboard_layout(&self) -> &dyn PlatformKeyboardLayout {
 428        self.keyboard_layout.as_ref()
 429    }
 430
 431    /// Get the current keyboard mapper.
 432    pub fn keyboard_mapper(&self) -> &Rc<dyn PlatformKeyboardMapper> {
 433        &self.keyboard_mapper
 434    }
 435
 436    /// Invokes a handler when the current keyboard layout changes
 437    pub fn on_keyboard_layout_change<F>(&self, mut callback: F) -> Subscription
 438    where
 439        F: 'static + FnMut(&mut App),
 440    {
 441        let (subscription, activate) = self.keyboard_layout_observers.insert(
 442            (),
 443            Box::new(move |cx| {
 444                callback(cx);
 445                true
 446            }),
 447        );
 448        activate();
 449        subscription
 450    }
 451
 452    /// Gracefully quit the application via the platform's standard routine.
 453    pub fn quit(&self) {
 454        self.platform.quit();
 455    }
 456
 457    /// Schedules all windows in the application to be redrawn. This can be called
 458    /// multiple times in an update cycle and still result in a single redraw.
 459    pub fn refresh_windows(&mut self) {
 460        self.pending_effects.push_back(Effect::RefreshWindows);
 461    }
 462
 463    pub(crate) fn update<R>(&mut self, update: impl FnOnce(&mut Self) -> R) -> R {
 464        self.start_update();
 465        let result = update(self);
 466        self.finish_update();
 467        result
 468    }
 469
 470    pub(crate) fn start_update(&mut self) {
 471        self.pending_updates += 1;
 472    }
 473
 474    pub(crate) fn finish_update(&mut self) {
 475        if !self.flushing_effects && self.pending_updates == 1 {
 476            self.flushing_effects = true;
 477            self.flush_effects();
 478            self.flushing_effects = false;
 479        }
 480        self.pending_updates -= 1;
 481    }
 482
 483    /// Arrange a callback to be invoked when the given entity calls `notify` on its respective context.
 484    pub fn observe<W>(
 485        &mut self,
 486        entity: &Entity<W>,
 487        mut on_notify: impl FnMut(Entity<W>, &mut App) + 'static,
 488    ) -> Subscription
 489    where
 490        W: 'static,
 491    {
 492        self.observe_internal(entity, move |e, cx| {
 493            on_notify(e, cx);
 494            true
 495        })
 496    }
 497
 498    pub(crate) fn detect_accessed_entities<R>(
 499        &mut self,
 500        callback: impl FnOnce(&mut App) -> R,
 501    ) -> (R, FxHashSet<EntityId>) {
 502        let accessed_entities_start = self.entities.accessed_entities.borrow().clone();
 503        let result = callback(self);
 504        let accessed_entities_end = self.entities.accessed_entities.borrow().clone();
 505        let entities_accessed_in_callback = accessed_entities_end
 506            .difference(&accessed_entities_start)
 507            .copied()
 508            .collect::<FxHashSet<EntityId>>();
 509        (result, entities_accessed_in_callback)
 510    }
 511
 512    pub(crate) fn record_entities_accessed(
 513        &mut self,
 514        window_handle: AnyWindowHandle,
 515        invalidator: WindowInvalidator,
 516        entities: &FxHashSet<EntityId>,
 517    ) {
 518        let mut tracked_entities =
 519            std::mem::take(self.tracked_entities.entry(window_handle.id).or_default());
 520        for entity in tracked_entities.iter() {
 521            self.window_invalidators_by_entity
 522                .entry(*entity)
 523                .and_modify(|windows| {
 524                    windows.remove(&window_handle.id);
 525                });
 526        }
 527        for entity in entities.iter() {
 528            self.window_invalidators_by_entity
 529                .entry(*entity)
 530                .or_default()
 531                .insert(window_handle.id, invalidator.clone());
 532        }
 533        tracked_entities.clear();
 534        tracked_entities.extend(entities.iter().copied());
 535        self.tracked_entities
 536            .insert(window_handle.id, tracked_entities);
 537    }
 538
 539    pub(crate) fn new_observer(&mut self, key: EntityId, value: Handler) -> Subscription {
 540        let (subscription, activate) = self.observers.insert(key, value);
 541        self.defer(move |_| activate());
 542        subscription
 543    }
 544
 545    pub(crate) fn observe_internal<W>(
 546        &mut self,
 547        entity: &Entity<W>,
 548        mut on_notify: impl FnMut(Entity<W>, &mut App) -> bool + 'static,
 549    ) -> Subscription
 550    where
 551        W: 'static,
 552    {
 553        let entity_id = entity.entity_id();
 554        let handle = entity.downgrade();
 555        self.new_observer(
 556            entity_id,
 557            Box::new(move |cx| {
 558                if let Some(entity) = handle.upgrade() {
 559                    on_notify(entity, cx)
 560                } else {
 561                    false
 562                }
 563            }),
 564        )
 565    }
 566
 567    /// Arrange for the given callback to be invoked whenever the given entity emits an event of a given type.
 568    /// The callback is provided a handle to the emitting entity and a reference to the emitted event.
 569    pub fn subscribe<T, Event>(
 570        &mut self,
 571        entity: &Entity<T>,
 572        mut on_event: impl FnMut(Entity<T>, &Event, &mut App) + 'static,
 573    ) -> Subscription
 574    where
 575        T: 'static + EventEmitter<Event>,
 576        Event: 'static,
 577    {
 578        self.subscribe_internal(entity, move |entity, event, cx| {
 579            on_event(entity, event, cx);
 580            true
 581        })
 582    }
 583
 584    pub(crate) fn new_subscription(
 585        &mut self,
 586        key: EntityId,
 587        value: (TypeId, Listener),
 588    ) -> Subscription {
 589        let (subscription, activate) = self.event_listeners.insert(key, value);
 590        self.defer(move |_| activate());
 591        subscription
 592    }
 593    pub(crate) fn subscribe_internal<T, Evt>(
 594        &mut self,
 595        entity: &Entity<T>,
 596        mut on_event: impl FnMut(Entity<T>, &Evt, &mut App) -> bool + 'static,
 597    ) -> Subscription
 598    where
 599        T: 'static + EventEmitter<Evt>,
 600        Evt: 'static,
 601    {
 602        let entity_id = entity.entity_id();
 603        let handle = entity.downgrade();
 604        self.new_subscription(
 605            entity_id,
 606            (
 607                TypeId::of::<Evt>(),
 608                Box::new(move |event, cx| {
 609                    let event: &Evt = event.downcast_ref().expect("invalid event type");
 610                    if let Some(entity) = handle.upgrade() {
 611                        on_event(entity, event, cx)
 612                    } else {
 613                        false
 614                    }
 615                }),
 616            ),
 617        )
 618    }
 619
 620    /// Returns handles to all open windows in the application.
 621    /// Each handle could be downcast to a handle typed for the root view of that window.
 622    /// To find all windows of a given type, you could filter on
 623    pub fn windows(&self) -> Vec<AnyWindowHandle> {
 624        self.windows
 625            .keys()
 626            .flat_map(|window_id| self.window_handles.get(&window_id).copied())
 627            .collect()
 628    }
 629
 630    /// Returns the window handles ordered by their appearance on screen, front to back.
 631    ///
 632    /// The first window in the returned list is the active/topmost window of the application.
 633    ///
 634    /// This method returns None if the platform doesn't implement the method yet.
 635    pub fn window_stack(&self) -> Option<Vec<AnyWindowHandle>> {
 636        self.platform.window_stack()
 637    }
 638
 639    /// Returns a handle to the window that is currently focused at the platform level, if one exists.
 640    pub fn active_window(&self) -> Option<AnyWindowHandle> {
 641        self.platform.active_window()
 642    }
 643
 644    /// Opens a new window with the given option and the root view returned by the given function.
 645    /// The function is invoked with a `Window`, which can be used to interact with window-specific
 646    /// functionality.
 647    pub fn open_window<V: 'static + Render>(
 648        &mut self,
 649        options: crate::WindowOptions,
 650        build_root_view: impl FnOnce(&mut Window, &mut App) -> Entity<V>,
 651    ) -> anyhow::Result<WindowHandle<V>> {
 652        self.update(|cx| {
 653            let id = cx.windows.insert(None);
 654            let handle = WindowHandle::new(id);
 655            match Window::new(handle.into(), options, cx) {
 656                Ok(mut window) => {
 657                    cx.window_update_stack.push(id);
 658                    let root_view = build_root_view(&mut window, cx);
 659                    cx.window_update_stack.pop();
 660                    window.root.replace(root_view.into());
 661                    window.defer(cx, |window: &mut Window, cx| window.appearance_changed(cx));
 662                    cx.window_handles.insert(id, window.handle);
 663                    cx.windows.get_mut(id).unwrap().replace(window);
 664                    Ok(handle)
 665                }
 666                Err(e) => {
 667                    cx.windows.remove(id);
 668                    Err(e)
 669                }
 670            }
 671        })
 672    }
 673
 674    /// Instructs the platform to activate the application by bringing it to the foreground.
 675    pub fn activate(&self, ignoring_other_apps: bool) {
 676        self.platform.activate(ignoring_other_apps);
 677    }
 678
 679    /// Hide the application at the platform level.
 680    pub fn hide(&self) {
 681        self.platform.hide();
 682    }
 683
 684    /// Hide other applications at the platform level.
 685    pub fn hide_other_apps(&self) {
 686        self.platform.hide_other_apps();
 687    }
 688
 689    /// Unhide other applications at the platform level.
 690    pub fn unhide_other_apps(&self) {
 691        self.platform.unhide_other_apps();
 692    }
 693
 694    /// Returns the list of currently active displays.
 695    pub fn displays(&self) -> Vec<Rc<dyn PlatformDisplay>> {
 696        self.platform.displays()
 697    }
 698
 699    /// Returns the primary display that will be used for new windows.
 700    pub fn primary_display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 701        self.platform.primary_display()
 702    }
 703
 704    /// Returns whether `screen_capture_sources` may work.
 705    pub fn is_screen_capture_supported(&self) -> bool {
 706        self.platform.is_screen_capture_supported()
 707    }
 708
 709    /// Returns a list of available screen capture sources.
 710    pub fn screen_capture_sources(
 711        &self,
 712    ) -> oneshot::Receiver<Result<Vec<Rc<dyn ScreenCaptureSource>>>> {
 713        self.platform.screen_capture_sources()
 714    }
 715
 716    /// Returns the display with the given ID, if one exists.
 717    pub fn find_display(&self, id: DisplayId) -> Option<Rc<dyn PlatformDisplay>> {
 718        self.displays()
 719            .iter()
 720            .find(|display| display.id() == id)
 721            .cloned()
 722    }
 723
 724    /// Returns the appearance of the application's windows.
 725    pub fn window_appearance(&self) -> WindowAppearance {
 726        self.platform.window_appearance()
 727    }
 728
 729    /// Writes data to the primary selection buffer.
 730    /// Only available on Linux.
 731    #[cfg(any(target_os = "linux", target_os = "freebsd"))]
 732    pub fn write_to_primary(&self, item: ClipboardItem) {
 733        self.platform.write_to_primary(item)
 734    }
 735
 736    /// Writes data to the platform clipboard.
 737    pub fn write_to_clipboard(&self, item: ClipboardItem) {
 738        self.platform.write_to_clipboard(item)
 739    }
 740
 741    /// Reads data from the primary selection buffer.
 742    /// Only available on Linux.
 743    #[cfg(any(target_os = "linux", target_os = "freebsd"))]
 744    pub fn read_from_primary(&self) -> Option<ClipboardItem> {
 745        self.platform.read_from_primary()
 746    }
 747
 748    /// Reads data from the platform clipboard.
 749    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
 750        self.platform.read_from_clipboard()
 751    }
 752
 753    /// Writes credentials to the platform keychain.
 754    pub fn write_credentials(
 755        &self,
 756        url: &str,
 757        username: &str,
 758        password: &[u8],
 759    ) -> Task<Result<()>> {
 760        self.platform.write_credentials(url, username, password)
 761    }
 762
 763    /// Reads credentials from the platform keychain.
 764    pub fn read_credentials(&self, url: &str) -> Task<Result<Option<(String, Vec<u8>)>>> {
 765        self.platform.read_credentials(url)
 766    }
 767
 768    /// Deletes credentials from the platform keychain.
 769    pub fn delete_credentials(&self, url: &str) -> Task<Result<()>> {
 770        self.platform.delete_credentials(url)
 771    }
 772
 773    /// Directs the platform's default browser to open the given URL.
 774    pub fn open_url(&self, url: &str) {
 775        self.platform.open_url(url);
 776    }
 777
 778    /// Registers the given URL scheme (e.g. `zed` for `zed://` urls) to be
 779    /// opened by the current app.
 780    ///
 781    /// On some platforms (e.g. macOS) you may be able to register URL schemes
 782    /// as part of app distribution, but this method exists to let you register
 783    /// schemes at runtime.
 784    pub fn register_url_scheme(&self, scheme: &str) -> Task<Result<()>> {
 785        self.platform.register_url_scheme(scheme)
 786    }
 787
 788    /// Returns the full pathname of the current app bundle.
 789    ///
 790    /// Returns an error if the app is not being run from a bundle.
 791    pub fn app_path(&self) -> Result<PathBuf> {
 792        self.platform.app_path()
 793    }
 794
 795    /// On Linux, returns the name of the compositor in use.
 796    ///
 797    /// Returns an empty string on other platforms.
 798    pub fn compositor_name(&self) -> &'static str {
 799        self.platform.compositor_name()
 800    }
 801
 802    /// Returns the file URL of the executable with the specified name in the application bundle
 803    pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
 804        self.platform.path_for_auxiliary_executable(name)
 805    }
 806
 807    /// Displays a platform modal for selecting paths.
 808    ///
 809    /// When one or more paths are selected, they'll be relayed asynchronously via the returned oneshot channel.
 810    /// If cancelled, a `None` will be relayed instead.
 811    /// May return an error on Linux if the file picker couldn't be opened.
 812    pub fn prompt_for_paths(
 813        &self,
 814        options: PathPromptOptions,
 815    ) -> oneshot::Receiver<Result<Option<Vec<PathBuf>>>> {
 816        self.platform.prompt_for_paths(options)
 817    }
 818
 819    /// Displays a platform modal for selecting a new path where a file can be saved.
 820    ///
 821    /// The provided directory will be used to set the initial location.
 822    /// When a path is selected, it is relayed asynchronously via the returned oneshot channel.
 823    /// If cancelled, a `None` will be relayed instead.
 824    /// May return an error on Linux if the file picker couldn't be opened.
 825    pub fn prompt_for_new_path(
 826        &self,
 827        directory: &Path,
 828        suggested_name: Option<&str>,
 829    ) -> oneshot::Receiver<Result<Option<PathBuf>>> {
 830        self.platform.prompt_for_new_path(directory, suggested_name)
 831    }
 832
 833    /// Reveals the specified path at the platform level, such as in Finder on macOS.
 834    pub fn reveal_path(&self, path: &Path) {
 835        self.platform.reveal_path(path)
 836    }
 837
 838    /// Opens the specified path with the system's default application.
 839    pub fn open_with_system(&self, path: &Path) {
 840        self.platform.open_with_system(path)
 841    }
 842
 843    /// Returns whether the user has configured scrollbars to auto-hide at the platform level.
 844    pub fn should_auto_hide_scrollbars(&self) -> bool {
 845        self.platform.should_auto_hide_scrollbars()
 846    }
 847
 848    /// Restarts the application.
 849    pub fn restart(&mut self) {
 850        self.restart_observers
 851            .clone()
 852            .retain(&(), |observer| observer(self));
 853        self.platform.restart(self.restart_path.take())
 854    }
 855
 856    /// Sets the path to use when restarting the application.
 857    pub fn set_restart_path(&mut self, path: PathBuf) {
 858        self.restart_path = Some(path);
 859    }
 860
 861    /// Returns the HTTP client for the application.
 862    pub fn http_client(&self) -> Arc<dyn HttpClient> {
 863        self.http_client.clone()
 864    }
 865
 866    /// Sets the HTTP client for the application.
 867    pub fn set_http_client(&mut self, new_client: Arc<dyn HttpClient>) {
 868        self.http_client = new_client;
 869    }
 870
 871    /// Returns the SVG renderer used by the application.
 872    pub fn svg_renderer(&self) -> SvgRenderer {
 873        self.svg_renderer.clone()
 874    }
 875
 876    pub(crate) fn push_effect(&mut self, effect: Effect) {
 877        match &effect {
 878            Effect::Notify { emitter } => {
 879                if !self.pending_notifications.insert(*emitter) {
 880                    return;
 881                }
 882            }
 883            Effect::NotifyGlobalObservers { global_type } => {
 884                if !self.pending_global_notifications.insert(*global_type) {
 885                    return;
 886                }
 887            }
 888            _ => {}
 889        };
 890
 891        self.pending_effects.push_back(effect);
 892    }
 893
 894    /// Called at the end of [`App::update`] to complete any side effects
 895    /// such as notifying observers, emitting events, etc. Effects can themselves
 896    /// cause effects, so we continue looping until all effects are processed.
 897    fn flush_effects(&mut self) {
 898        loop {
 899            self.release_dropped_entities();
 900            self.release_dropped_focus_handles();
 901            if let Some(effect) = self.pending_effects.pop_front() {
 902                match effect {
 903                    Effect::Notify { emitter } => {
 904                        self.apply_notify_effect(emitter);
 905                    }
 906
 907                    Effect::Emit {
 908                        emitter,
 909                        event_type,
 910                        event,
 911                    } => self.apply_emit_effect(emitter, event_type, event),
 912
 913                    Effect::RefreshWindows => {
 914                        self.apply_refresh_effect();
 915                    }
 916
 917                    Effect::NotifyGlobalObservers { global_type } => {
 918                        self.apply_notify_global_observers_effect(global_type);
 919                    }
 920
 921                    Effect::Defer { callback } => {
 922                        self.apply_defer_effect(callback);
 923                    }
 924                    Effect::EntityCreated {
 925                        entity,
 926                        tid,
 927                        window,
 928                    } => {
 929                        self.apply_entity_created_effect(entity, tid, window);
 930                    }
 931                }
 932            } else {
 933                #[cfg(any(test, feature = "test-support"))]
 934                for window in self
 935                    .windows
 936                    .values()
 937                    .filter_map(|window| {
 938                        let window = window.as_ref()?;
 939                        window.invalidator.is_dirty().then_some(window.handle)
 940                    })
 941                    .collect::<Vec<_>>()
 942                {
 943                    self.update_window(window, |_, window, cx| window.draw(cx).clear())
 944                        .unwrap();
 945                }
 946
 947                if self.pending_effects.is_empty() {
 948                    break;
 949                }
 950            }
 951        }
 952    }
 953
 954    /// Repeatedly called during `flush_effects` to release any entities whose
 955    /// reference count has become zero. We invoke any release observers before dropping
 956    /// each entity.
 957    fn release_dropped_entities(&mut self) {
 958        loop {
 959            let dropped = self.entities.take_dropped();
 960            if dropped.is_empty() {
 961                break;
 962            }
 963
 964            for (entity_id, mut entity) in dropped {
 965                self.observers.remove(&entity_id);
 966                self.event_listeners.remove(&entity_id);
 967                for release_callback in self.release_listeners.remove(&entity_id) {
 968                    release_callback(entity.as_mut(), self);
 969                }
 970            }
 971        }
 972    }
 973
 974    /// Repeatedly called during `flush_effects` to handle a focused handle being dropped.
 975    fn release_dropped_focus_handles(&mut self) {
 976        self.focus_handles
 977            .clone()
 978            .write()
 979            .retain(|handle_id, focus| {
 980                if focus.ref_count.load(SeqCst) == 0 {
 981                    for window_handle in self.windows() {
 982                        window_handle
 983                            .update(self, |_, window, _| {
 984                                if window.focus == Some(handle_id) {
 985                                    window.blur();
 986                                }
 987                            })
 988                            .unwrap();
 989                    }
 990                    false
 991                } else {
 992                    true
 993                }
 994            });
 995    }
 996
 997    fn apply_notify_effect(&mut self, emitter: EntityId) {
 998        self.pending_notifications.remove(&emitter);
 999
1000        self.observers
1001            .clone()
1002            .retain(&emitter, |handler| handler(self));
1003    }
1004
1005    fn apply_emit_effect(&mut self, emitter: EntityId, event_type: TypeId, event: Box<dyn Any>) {
1006        self.event_listeners
1007            .clone()
1008            .retain(&emitter, |(stored_type, handler)| {
1009                if *stored_type == event_type {
1010                    handler(event.as_ref(), self)
1011                } else {
1012                    true
1013                }
1014            });
1015    }
1016
1017    fn apply_refresh_effect(&mut self) {
1018        for window in self.windows.values_mut() {
1019            if let Some(window) = window.as_mut() {
1020                window.refreshing = true;
1021                window.invalidator.set_dirty(true);
1022            }
1023        }
1024    }
1025
1026    fn apply_notify_global_observers_effect(&mut self, type_id: TypeId) {
1027        self.pending_global_notifications.remove(&type_id);
1028        self.global_observers
1029            .clone()
1030            .retain(&type_id, |observer| observer(self));
1031    }
1032
1033    fn apply_defer_effect(&mut self, callback: Box<dyn FnOnce(&mut Self) + 'static>) {
1034        callback(self);
1035    }
1036
1037    fn apply_entity_created_effect(
1038        &mut self,
1039        entity: AnyEntity,
1040        tid: TypeId,
1041        window: Option<WindowId>,
1042    ) {
1043        self.new_entity_observers.clone().retain(&tid, |observer| {
1044            if let Some(id) = window {
1045                self.update_window_id(id, {
1046                    let entity = entity.clone();
1047                    |_, window, cx| (observer)(entity, &mut Some(window), cx)
1048                })
1049                .expect("All windows should be off the stack when flushing effects");
1050            } else {
1051                (observer)(entity.clone(), &mut None, self)
1052            }
1053            true
1054        });
1055    }
1056
1057    fn update_window_id<T, F>(&mut self, id: WindowId, update: F) -> Result<T>
1058    where
1059        F: FnOnce(AnyView, &mut Window, &mut App) -> T,
1060    {
1061        self.update(|cx| {
1062            let mut window = cx
1063                .windows
1064                .get_mut(id)
1065                .context("window not found")?
1066                .take()
1067                .context("window not found")?;
1068
1069            let root_view = window.root.clone().unwrap();
1070
1071            cx.window_update_stack.push(window.handle.id);
1072            let result = update(root_view, &mut window, cx);
1073            cx.window_update_stack.pop();
1074
1075            if window.removed {
1076                cx.window_handles.remove(&id);
1077                cx.windows.remove(id);
1078
1079                cx.window_closed_observers.clone().retain(&(), |callback| {
1080                    callback(cx);
1081                    true
1082                });
1083            } else {
1084                cx.windows
1085                    .get_mut(id)
1086                    .context("window not found")?
1087                    .replace(window);
1088            }
1089
1090            Ok(result)
1091        })
1092    }
1093    /// Creates an `AsyncApp`, which can be cloned and has a static lifetime
1094    /// so it can be held across `await` points.
1095    pub fn to_async(&self) -> AsyncApp {
1096        AsyncApp {
1097            app: self.this.clone(),
1098            background_executor: self.background_executor.clone(),
1099            foreground_executor: self.foreground_executor.clone(),
1100        }
1101    }
1102
1103    /// Obtains a reference to the executor, which can be used to spawn futures.
1104    pub fn background_executor(&self) -> &BackgroundExecutor {
1105        &self.background_executor
1106    }
1107
1108    /// Obtains a reference to the executor, which can be used to spawn futures.
1109    pub fn foreground_executor(&self) -> &ForegroundExecutor {
1110        if self.quitting {
1111            panic!("Can't spawn on main thread after on_app_quit")
1112        };
1113        &self.foreground_executor
1114    }
1115
1116    /// Spawns the future returned by the given function on the main thread. The closure will be invoked
1117    /// with [AsyncApp], which allows the application state to be accessed across await points.
1118    #[track_caller]
1119    pub fn spawn<AsyncFn, R>(&self, f: AsyncFn) -> Task<R>
1120    where
1121        AsyncFn: AsyncFnOnce(&mut AsyncApp) -> R + 'static,
1122        R: 'static,
1123    {
1124        if self.quitting {
1125            debug_panic!("Can't spawn on main thread after on_app_quit")
1126        };
1127
1128        let mut cx = self.to_async();
1129
1130        self.foreground_executor
1131            .spawn(async move { f(&mut cx).await })
1132    }
1133
1134    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
1135    /// that are currently on the stack to be returned to the app.
1136    pub fn defer(&mut self, f: impl FnOnce(&mut App) + 'static) {
1137        self.push_effect(Effect::Defer {
1138            callback: Box::new(f),
1139        });
1140    }
1141
1142    /// Accessor for the application's asset source, which is provided when constructing the `App`.
1143    pub fn asset_source(&self) -> &Arc<dyn AssetSource> {
1144        &self.asset_source
1145    }
1146
1147    /// Accessor for the text system.
1148    pub fn text_system(&self) -> &Arc<TextSystem> {
1149        &self.text_system
1150    }
1151
1152    /// Check whether a global of the given type has been assigned.
1153    pub fn has_global<G: Global>(&self) -> bool {
1154        self.globals_by_type.contains_key(&TypeId::of::<G>())
1155    }
1156
1157    /// Access the global of the given type. Panics if a global for that type has not been assigned.
1158    #[track_caller]
1159    pub fn global<G: Global>(&self) -> &G {
1160        self.globals_by_type
1161            .get(&TypeId::of::<G>())
1162            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
1163            .with_context(|| format!("no state of type {} exists", type_name::<G>()))
1164            .unwrap()
1165    }
1166
1167    /// Access the global of the given type if a value has been assigned.
1168    pub fn try_global<G: Global>(&self) -> Option<&G> {
1169        self.globals_by_type
1170            .get(&TypeId::of::<G>())
1171            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
1172    }
1173
1174    /// Access the global of the given type mutably. Panics if a global for that type has not been assigned.
1175    #[track_caller]
1176    pub fn global_mut<G: Global>(&mut self) -> &mut G {
1177        let global_type = TypeId::of::<G>();
1178        self.push_effect(Effect::NotifyGlobalObservers { global_type });
1179        self.globals_by_type
1180            .get_mut(&global_type)
1181            .and_then(|any_state| any_state.downcast_mut::<G>())
1182            .with_context(|| format!("no state of type {} exists", type_name::<G>()))
1183            .unwrap()
1184    }
1185
1186    /// Access the global of the given type mutably. A default value is assigned if a global of this type has not
1187    /// yet been assigned.
1188    pub fn default_global<G: Global + Default>(&mut self) -> &mut G {
1189        let global_type = TypeId::of::<G>();
1190        self.push_effect(Effect::NotifyGlobalObservers { global_type });
1191        self.globals_by_type
1192            .entry(global_type)
1193            .or_insert_with(|| Box::<G>::default())
1194            .downcast_mut::<G>()
1195            .unwrap()
1196    }
1197
1198    /// Sets the value of the global of the given type.
1199    pub fn set_global<G: Global>(&mut self, global: G) {
1200        let global_type = TypeId::of::<G>();
1201        self.push_effect(Effect::NotifyGlobalObservers { global_type });
1202        self.globals_by_type.insert(global_type, Box::new(global));
1203    }
1204
1205    /// Clear all stored globals. Does not notify global observers.
1206    #[cfg(any(test, feature = "test-support"))]
1207    pub fn clear_globals(&mut self) {
1208        self.globals_by_type.drain();
1209    }
1210
1211    /// Remove the global of the given type from the app context. Does not notify global observers.
1212    pub fn remove_global<G: Global>(&mut self) -> G {
1213        let global_type = TypeId::of::<G>();
1214        self.push_effect(Effect::NotifyGlobalObservers { global_type });
1215        *self
1216            .globals_by_type
1217            .remove(&global_type)
1218            .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<G>()))
1219            .downcast()
1220            .unwrap()
1221    }
1222
1223    /// Register a callback to be invoked when a global of the given type is updated.
1224    pub fn observe_global<G: Global>(
1225        &mut self,
1226        mut f: impl FnMut(&mut Self) + 'static,
1227    ) -> Subscription {
1228        let (subscription, activate) = self.global_observers.insert(
1229            TypeId::of::<G>(),
1230            Box::new(move |cx| {
1231                f(cx);
1232                true
1233            }),
1234        );
1235        self.defer(move |_| activate());
1236        subscription
1237    }
1238
1239    /// Move the global of the given type to the stack.
1240    #[track_caller]
1241    pub(crate) fn lease_global<G: Global>(&mut self) -> GlobalLease<G> {
1242        GlobalLease::new(
1243            self.globals_by_type
1244                .remove(&TypeId::of::<G>())
1245                .with_context(|| format!("no global registered of type {}", type_name::<G>()))
1246                .unwrap(),
1247        )
1248    }
1249
1250    /// Restore the global of the given type after it is moved to the stack.
1251    pub(crate) fn end_global_lease<G: Global>(&mut self, lease: GlobalLease<G>) {
1252        let global_type = TypeId::of::<G>();
1253
1254        self.push_effect(Effect::NotifyGlobalObservers { global_type });
1255        self.globals_by_type.insert(global_type, lease.global);
1256    }
1257
1258    pub(crate) fn new_entity_observer(
1259        &self,
1260        key: TypeId,
1261        value: NewEntityListener,
1262    ) -> Subscription {
1263        let (subscription, activate) = self.new_entity_observers.insert(key, value);
1264        activate();
1265        subscription
1266    }
1267
1268    /// Arrange for the given function to be invoked whenever a view of the specified type is created.
1269    /// The function will be passed a mutable reference to the view along with an appropriate context.
1270    pub fn observe_new<T: 'static>(
1271        &self,
1272        on_new: impl 'static + Fn(&mut T, Option<&mut Window>, &mut Context<T>),
1273    ) -> Subscription {
1274        self.new_entity_observer(
1275            TypeId::of::<T>(),
1276            Box::new(
1277                move |any_entity: AnyEntity, window: &mut Option<&mut Window>, cx: &mut App| {
1278                    any_entity
1279                        .downcast::<T>()
1280                        .unwrap()
1281                        .update(cx, |entity_state, cx| {
1282                            on_new(entity_state, window.as_deref_mut(), cx)
1283                        })
1284                },
1285            ),
1286        )
1287    }
1288
1289    /// Observe the release of a entity. The callback is invoked after the entity
1290    /// has no more strong references but before it has been dropped.
1291    pub fn observe_release<T>(
1292        &self,
1293        handle: &Entity<T>,
1294        on_release: impl FnOnce(&mut T, &mut App) + 'static,
1295    ) -> Subscription
1296    where
1297        T: 'static,
1298    {
1299        let (subscription, activate) = self.release_listeners.insert(
1300            handle.entity_id(),
1301            Box::new(move |entity, cx| {
1302                let entity = entity.downcast_mut().expect("invalid entity type");
1303                on_release(entity, cx)
1304            }),
1305        );
1306        activate();
1307        subscription
1308    }
1309
1310    /// Observe the release of a entity. The callback is invoked after the entity
1311    /// has no more strong references but before it has been dropped.
1312    pub fn observe_release_in<T>(
1313        &self,
1314        handle: &Entity<T>,
1315        window: &Window,
1316        on_release: impl FnOnce(&mut T, &mut Window, &mut App) + 'static,
1317    ) -> Subscription
1318    where
1319        T: 'static,
1320    {
1321        let window_handle = window.handle;
1322        self.observe_release(handle, move |entity, cx| {
1323            let _ = window_handle.update(cx, |_, window, cx| on_release(entity, window, cx));
1324        })
1325    }
1326
1327    /// Register a callback to be invoked when a keystroke is received by the application
1328    /// in any window. Note that this fires after all other action and event mechanisms have resolved
1329    /// and that this API will not be invoked if the event's propagation is stopped.
1330    pub fn observe_keystrokes(
1331        &mut self,
1332        mut f: impl FnMut(&KeystrokeEvent, &mut Window, &mut App) + 'static,
1333    ) -> Subscription {
1334        fn inner(
1335            keystroke_observers: &SubscriberSet<(), KeystrokeObserver>,
1336            handler: KeystrokeObserver,
1337        ) -> Subscription {
1338            let (subscription, activate) = keystroke_observers.insert((), handler);
1339            activate();
1340            subscription
1341        }
1342
1343        inner(
1344            &self.keystroke_observers,
1345            Box::new(move |event, window, cx| {
1346                f(event, window, cx);
1347                true
1348            }),
1349        )
1350    }
1351
1352    /// Register a callback to be invoked when a keystroke is received by the application
1353    /// in any window. Note that this fires _before_ all other action and event mechanisms have resolved
1354    /// unlike [`App::observe_keystrokes`] which fires after. This means that `cx.stop_propagation` calls
1355    /// within interceptors will prevent action dispatch
1356    pub fn intercept_keystrokes(
1357        &mut self,
1358        mut f: impl FnMut(&KeystrokeEvent, &mut Window, &mut App) + 'static,
1359    ) -> Subscription {
1360        fn inner(
1361            keystroke_interceptors: &SubscriberSet<(), KeystrokeObserver>,
1362            handler: KeystrokeObserver,
1363        ) -> Subscription {
1364            let (subscription, activate) = keystroke_interceptors.insert((), handler);
1365            activate();
1366            subscription
1367        }
1368
1369        inner(
1370            &self.keystroke_interceptors,
1371            Box::new(move |event, window, cx| {
1372                f(event, window, cx);
1373                true
1374            }),
1375        )
1376    }
1377
1378    /// Register key bindings.
1379    pub fn bind_keys(&mut self, bindings: impl IntoIterator<Item = KeyBinding>) {
1380        self.keymap.borrow_mut().add_bindings(bindings);
1381        self.pending_effects.push_back(Effect::RefreshWindows);
1382    }
1383
1384    /// Clear all key bindings in the app.
1385    pub fn clear_key_bindings(&mut self) {
1386        self.keymap.borrow_mut().clear();
1387        self.pending_effects.push_back(Effect::RefreshWindows);
1388    }
1389
1390    /// Get all key bindings in the app.
1391    pub fn key_bindings(&self) -> Rc<RefCell<Keymap>> {
1392        self.keymap.clone()
1393    }
1394
1395    /// Register a global handler for actions invoked via the keyboard. These handlers are run at
1396    /// the end of the bubble phase for actions, and so will only be invoked if there are no other
1397    /// handlers or if they called `cx.propagate()`.
1398    pub fn on_action<A: Action>(&mut self, listener: impl Fn(&A, &mut Self) + 'static) {
1399        self.global_action_listeners
1400            .entry(TypeId::of::<A>())
1401            .or_default()
1402            .push(Rc::new(move |action, phase, cx| {
1403                if phase == DispatchPhase::Bubble {
1404                    let action = action.downcast_ref().unwrap();
1405                    listener(action, cx)
1406                }
1407            }));
1408    }
1409
1410    /// Event handlers propagate events by default. Call this method to stop dispatching to
1411    /// event handlers with a lower z-index (mouse) or higher in the tree (keyboard). This is
1412    /// the opposite of [`Self::propagate`]. It's also possible to cancel a call to [`Self::propagate`] by
1413    /// calling this method before effects are flushed.
1414    pub fn stop_propagation(&mut self) {
1415        self.propagate_event = false;
1416    }
1417
1418    /// Action handlers stop propagation by default during the bubble phase of action dispatch
1419    /// dispatching to action handlers higher in the element tree. This is the opposite of
1420    /// [`Self::stop_propagation`]. It's also possible to cancel a call to [`Self::stop_propagation`] by calling
1421    /// this method before effects are flushed.
1422    pub fn propagate(&mut self) {
1423        self.propagate_event = true;
1424    }
1425
1426    /// Build an action from some arbitrary data, typically a keymap entry.
1427    pub fn build_action(
1428        &self,
1429        name: &str,
1430        data: Option<serde_json::Value>,
1431    ) -> std::result::Result<Box<dyn Action>, ActionBuildError> {
1432        self.actions.build_action(name, data)
1433    }
1434
1435    /// Get all action names that have been registered. Note that registration only allows for
1436    /// actions to be built dynamically, and is unrelated to binding actions in the element tree.
1437    pub fn all_action_names(&self) -> &[&'static str] {
1438        self.actions.all_action_names()
1439    }
1440
1441    /// Returns key bindings that invoke the given action on the currently focused element, without
1442    /// checking context. Bindings are returned in the order they were added. For display, the last
1443    /// binding should take precedence.
1444    pub fn all_bindings_for_input(&self, input: &[Keystroke]) -> Vec<KeyBinding> {
1445        RefCell::borrow(&self.keymap).all_bindings_for_input(input)
1446    }
1447
1448    /// Get all non-internal actions that have been registered, along with their schemas.
1449    pub fn action_schemas(
1450        &self,
1451        generator: &mut schemars::SchemaGenerator,
1452    ) -> Vec<(&'static str, Option<schemars::Schema>)> {
1453        self.actions.action_schemas(generator)
1454    }
1455
1456    /// Get a map from a deprecated action name to the canonical name.
1457    pub fn deprecated_actions_to_preferred_actions(&self) -> &HashMap<&'static str, &'static str> {
1458        self.actions.deprecated_aliases()
1459    }
1460
1461    /// Get a map from an action name to the deprecation messages.
1462    pub fn action_deprecation_messages(&self) -> &HashMap<&'static str, &'static str> {
1463        self.actions.deprecation_messages()
1464    }
1465
1466    /// Get a map from an action name to the documentation.
1467    pub fn action_documentation(&self) -> &HashMap<&'static str, &'static str> {
1468        self.actions.documentation()
1469    }
1470
1471    /// Register a callback to be invoked when the application is about to quit.
1472    /// It is not possible to cancel the quit event at this point.
1473    pub fn on_app_quit<Fut>(
1474        &self,
1475        mut on_quit: impl FnMut(&mut App) -> Fut + 'static,
1476    ) -> Subscription
1477    where
1478        Fut: 'static + Future<Output = ()>,
1479    {
1480        let (subscription, activate) = self.quit_observers.insert(
1481            (),
1482            Box::new(move |cx| {
1483                let future = on_quit(cx);
1484                future.boxed_local()
1485            }),
1486        );
1487        activate();
1488        subscription
1489    }
1490
1491    /// Register a callback to be invoked when the application is about to restart.
1492    ///
1493    /// These callbacks are called before any `on_app_quit` callbacks.
1494    pub fn on_app_restart(&self, mut on_restart: impl 'static + FnMut(&mut App)) -> Subscription {
1495        let (subscription, activate) = self.restart_observers.insert(
1496            (),
1497            Box::new(move |cx| {
1498                on_restart(cx);
1499                true
1500            }),
1501        );
1502        activate();
1503        subscription
1504    }
1505
1506    /// Register a callback to be invoked when a window is closed
1507    /// The window is no longer accessible at the point this callback is invoked.
1508    pub fn on_window_closed(&self, mut on_closed: impl FnMut(&mut App) + 'static) -> Subscription {
1509        let (subscription, activate) = self.window_closed_observers.insert((), Box::new(on_closed));
1510        activate();
1511        subscription
1512    }
1513
1514    pub(crate) fn clear_pending_keystrokes(&mut self) {
1515        for window in self.windows() {
1516            window
1517                .update(self, |_, window, _| {
1518                    window.clear_pending_keystrokes();
1519                })
1520                .ok();
1521        }
1522    }
1523
1524    /// Checks if the given action is bound in the current context, as defined by the app's current focus,
1525    /// the bindings in the element tree, and any global action listeners.
1526    pub fn is_action_available(&mut self, action: &dyn Action) -> bool {
1527        let mut action_available = false;
1528        if let Some(window) = self.active_window()
1529            && let Ok(window_action_available) =
1530                window.update(self, |_, window, cx| window.is_action_available(action, cx))
1531        {
1532            action_available = window_action_available;
1533        }
1534
1535        action_available
1536            || self
1537                .global_action_listeners
1538                .contains_key(&action.as_any().type_id())
1539    }
1540
1541    /// Sets the menu bar for this application. This will replace any existing menu bar.
1542    pub fn set_menus(&self, menus: Vec<Menu>) {
1543        self.platform.set_menus(menus, &self.keymap.borrow());
1544    }
1545
1546    /// Gets the menu bar for this application.
1547    pub fn get_menus(&self) -> Option<Vec<OwnedMenu>> {
1548        self.platform.get_menus()
1549    }
1550
1551    /// Sets the right click menu for the app icon in the dock
1552    pub fn set_dock_menu(&self, menus: Vec<MenuItem>) {
1553        self.platform.set_dock_menu(menus, &self.keymap.borrow())
1554    }
1555
1556    /// Performs the action associated with the given dock menu item, only used on Windows for now.
1557    pub fn perform_dock_menu_action(&self, action: usize) {
1558        self.platform.perform_dock_menu_action(action);
1559    }
1560
1561    /// Adds given path to the bottom of the list of recent paths for the application.
1562    /// The list is usually shown on the application icon's context menu in the dock,
1563    /// and allows to open the recent files via that context menu.
1564    /// If the path is already in the list, it will be moved to the bottom of the list.
1565    pub fn add_recent_document(&self, path: &Path) {
1566        self.platform.add_recent_document(path);
1567    }
1568
1569    /// Updates the jump list with the updated list of recent paths for the application, only used on Windows for now.
1570    /// Note that this also sets the dock menu on Windows.
1571    pub fn update_jump_list(
1572        &self,
1573        menus: Vec<MenuItem>,
1574        entries: Vec<SmallVec<[PathBuf; 2]>>,
1575    ) -> Vec<SmallVec<[PathBuf; 2]>> {
1576        self.platform.update_jump_list(menus, entries)
1577    }
1578
1579    /// Dispatch an action to the currently active window or global action handler
1580    /// See [`crate::Action`] for more information on how actions work
1581    pub fn dispatch_action(&mut self, action: &dyn Action) {
1582        if let Some(active_window) = self.active_window() {
1583            active_window
1584                .update(self, |_, window, cx| {
1585                    window.dispatch_action(action.boxed_clone(), cx)
1586                })
1587                .log_err();
1588        } else {
1589            self.dispatch_global_action(action);
1590        }
1591    }
1592
1593    fn dispatch_global_action(&mut self, action: &dyn Action) {
1594        self.propagate_event = true;
1595
1596        if let Some(mut global_listeners) = self
1597            .global_action_listeners
1598            .remove(&action.as_any().type_id())
1599        {
1600            for listener in &global_listeners {
1601                listener(action.as_any(), DispatchPhase::Capture, self);
1602                if !self.propagate_event {
1603                    break;
1604                }
1605            }
1606
1607            global_listeners.extend(
1608                self.global_action_listeners
1609                    .remove(&action.as_any().type_id())
1610                    .unwrap_or_default(),
1611            );
1612
1613            self.global_action_listeners
1614                .insert(action.as_any().type_id(), global_listeners);
1615        }
1616
1617        if self.propagate_event
1618            && let Some(mut global_listeners) = self
1619                .global_action_listeners
1620                .remove(&action.as_any().type_id())
1621        {
1622            for listener in global_listeners.iter().rev() {
1623                listener(action.as_any(), DispatchPhase::Bubble, self);
1624                if !self.propagate_event {
1625                    break;
1626                }
1627            }
1628
1629            global_listeners.extend(
1630                self.global_action_listeners
1631                    .remove(&action.as_any().type_id())
1632                    .unwrap_or_default(),
1633            );
1634
1635            self.global_action_listeners
1636                .insert(action.as_any().type_id(), global_listeners);
1637        }
1638    }
1639
1640    /// Is there currently something being dragged?
1641    pub fn has_active_drag(&self) -> bool {
1642        self.active_drag.is_some()
1643    }
1644
1645    /// Gets the cursor style of the currently active drag operation.
1646    pub fn active_drag_cursor_style(&self) -> Option<CursorStyle> {
1647        self.active_drag.as_ref().and_then(|drag| drag.cursor_style)
1648    }
1649
1650    /// Stops active drag and clears any related effects.
1651    pub fn stop_active_drag(&mut self, window: &mut Window) -> bool {
1652        if self.active_drag.is_some() {
1653            self.active_drag = None;
1654            window.refresh();
1655            true
1656        } else {
1657            false
1658        }
1659    }
1660
1661    /// Sets the cursor style for the currently active drag operation.
1662    pub fn set_active_drag_cursor_style(
1663        &mut self,
1664        cursor_style: CursorStyle,
1665        window: &mut Window,
1666    ) -> bool {
1667        if let Some(ref mut drag) = self.active_drag {
1668            drag.cursor_style = Some(cursor_style);
1669            window.refresh();
1670            true
1671        } else {
1672            false
1673        }
1674    }
1675
1676    /// Set the prompt renderer for GPUI. This will replace the default or platform specific
1677    /// prompts with this custom implementation.
1678    pub fn set_prompt_builder(
1679        &mut self,
1680        renderer: impl Fn(
1681            PromptLevel,
1682            &str,
1683            Option<&str>,
1684            &[PromptButton],
1685            PromptHandle,
1686            &mut Window,
1687            &mut App,
1688        ) -> RenderablePromptHandle
1689        + 'static,
1690    ) {
1691        self.prompt_builder = Some(PromptBuilder::Custom(Box::new(renderer)));
1692    }
1693
1694    /// Reset the prompt builder to the default implementation.
1695    pub fn reset_prompt_builder(&mut self) {
1696        self.prompt_builder = Some(PromptBuilder::Default);
1697    }
1698
1699    /// Remove an asset from GPUI's cache
1700    pub fn remove_asset<A: Asset>(&mut self, source: &A::Source) {
1701        let asset_id = (TypeId::of::<A>(), hash(source));
1702        self.loading_assets.remove(&asset_id);
1703    }
1704
1705    /// Asynchronously load an asset, if the asset hasn't finished loading this will return None.
1706    ///
1707    /// Note that the multiple calls to this method will only result in one `Asset::load` call at a
1708    /// time, and the results of this call will be cached
1709    pub fn fetch_asset<A: Asset>(&mut self, source: &A::Source) -> (Shared<Task<A::Output>>, bool) {
1710        let asset_id = (TypeId::of::<A>(), hash(source));
1711        let mut is_first = false;
1712        let task = self
1713            .loading_assets
1714            .remove(&asset_id)
1715            .map(|boxed_task| *boxed_task.downcast::<Shared<Task<A::Output>>>().unwrap())
1716            .unwrap_or_else(|| {
1717                is_first = true;
1718                let future = A::load(source.clone(), self);
1719
1720                self.background_executor().spawn(future).shared()
1721            });
1722
1723        self.loading_assets.insert(asset_id, Box::new(task.clone()));
1724
1725        (task, is_first)
1726    }
1727
1728    /// Obtain a new [`FocusHandle`], which allows you to track and manipulate the keyboard focus
1729    /// for elements rendered within this window.
1730    #[track_caller]
1731    pub fn focus_handle(&self) -> FocusHandle {
1732        FocusHandle::new(&self.focus_handles)
1733    }
1734
1735    /// Tell GPUI that an entity has changed and observers of it should be notified.
1736    pub fn notify(&mut self, entity_id: EntityId) {
1737        let window_invalidators = mem::take(
1738            self.window_invalidators_by_entity
1739                .entry(entity_id)
1740                .or_default(),
1741        );
1742
1743        if window_invalidators.is_empty() {
1744            if self.pending_notifications.insert(entity_id) {
1745                self.pending_effects
1746                    .push_back(Effect::Notify { emitter: entity_id });
1747            }
1748        } else {
1749            for invalidator in window_invalidators.values() {
1750                invalidator.invalidate_view(entity_id, self);
1751            }
1752        }
1753
1754        self.window_invalidators_by_entity
1755            .insert(entity_id, window_invalidators);
1756    }
1757
1758    /// Returns the name for this [`App`].
1759    #[cfg(any(test, feature = "test-support", debug_assertions))]
1760    pub fn get_name(&self) -> Option<&'static str> {
1761        self.name
1762    }
1763
1764    /// Returns `true` if the platform file picker supports selecting a mix of files and directories.
1765    pub fn can_select_mixed_files_and_dirs(&self) -> bool {
1766        self.platform.can_select_mixed_files_and_dirs()
1767    }
1768
1769    /// Removes an image from the sprite atlas on all windows.
1770    ///
1771    /// If the current window is being updated, it will be removed from `App.windows`, you can use `current_window` to specify the current window.
1772    /// This is a no-op if the image is not in the sprite atlas.
1773    pub fn drop_image(&mut self, image: Arc<RenderImage>, current_window: Option<&mut Window>) {
1774        // remove the texture from all other windows
1775        for window in self.windows.values_mut().flatten() {
1776            _ = window.drop_image(image.clone());
1777        }
1778
1779        // remove the texture from the current window
1780        if let Some(window) = current_window {
1781            _ = window.drop_image(image);
1782        }
1783    }
1784
1785    /// Sets the renderer for the inspector.
1786    #[cfg(any(feature = "inspector", debug_assertions))]
1787    pub fn set_inspector_renderer(&mut self, f: crate::InspectorRenderer) {
1788        self.inspector_renderer = Some(f);
1789    }
1790
1791    /// Registers a renderer specific to an inspector state.
1792    #[cfg(any(feature = "inspector", debug_assertions))]
1793    pub fn register_inspector_element<T: 'static, R: crate::IntoElement>(
1794        &mut self,
1795        f: impl 'static + Fn(crate::InspectorElementId, &T, &mut Window, &mut App) -> R,
1796    ) {
1797        self.inspector_element_registry.register(f);
1798    }
1799
1800    /// Initializes gpui's default colors for the application.
1801    ///
1802    /// These colors can be accessed through `cx.default_colors()`.
1803    pub fn init_colors(&mut self) {
1804        self.set_global(GlobalColors(Arc::new(Colors::default())));
1805    }
1806}
1807
1808impl AppContext for App {
1809    type Result<T> = T;
1810
1811    /// Builds an entity that is owned by the application.
1812    ///
1813    /// The given function will be invoked with a [`Context`] and must return an object representing the entity. An
1814    /// [`Entity`] handle will be returned, which can be used to access the entity in a context.
1815    fn new<T: 'static>(&mut self, build_entity: impl FnOnce(&mut Context<T>) -> T) -> Entity<T> {
1816        self.update(|cx| {
1817            let slot = cx.entities.reserve();
1818            let handle = slot.clone();
1819            let entity = build_entity(&mut Context::new_context(cx, slot.downgrade()));
1820
1821            cx.push_effect(Effect::EntityCreated {
1822                entity: handle.clone().into_any(),
1823                tid: TypeId::of::<T>(),
1824                window: cx.window_update_stack.last().cloned(),
1825            });
1826
1827            cx.entities.insert(slot, entity);
1828            handle
1829        })
1830    }
1831
1832    fn reserve_entity<T: 'static>(&mut self) -> Self::Result<Reservation<T>> {
1833        Reservation(self.entities.reserve())
1834    }
1835
1836    fn insert_entity<T: 'static>(
1837        &mut self,
1838        reservation: Reservation<T>,
1839        build_entity: impl FnOnce(&mut Context<T>) -> T,
1840    ) -> Self::Result<Entity<T>> {
1841        self.update(|cx| {
1842            let slot = reservation.0;
1843            let entity = build_entity(&mut Context::new_context(cx, slot.downgrade()));
1844            cx.entities.insert(slot, entity)
1845        })
1846    }
1847
1848    /// Updates the entity referenced by the given handle. The function is passed a mutable reference to the
1849    /// entity along with a `Context` for the entity.
1850    fn update_entity<T: 'static, R>(
1851        &mut self,
1852        handle: &Entity<T>,
1853        update: impl FnOnce(&mut T, &mut Context<T>) -> R,
1854    ) -> R {
1855        self.update(|cx| {
1856            let mut entity = cx.entities.lease(handle);
1857            let result = update(
1858                &mut entity,
1859                &mut Context::new_context(cx, handle.downgrade()),
1860            );
1861            cx.entities.end_lease(entity);
1862            result
1863        })
1864    }
1865
1866    fn as_mut<'a, T>(&'a mut self, handle: &Entity<T>) -> GpuiBorrow<'a, T>
1867    where
1868        T: 'static,
1869    {
1870        GpuiBorrow::new(handle.clone(), self)
1871    }
1872
1873    fn read_entity<T, R>(
1874        &self,
1875        handle: &Entity<T>,
1876        read: impl FnOnce(&T, &App) -> R,
1877    ) -> Self::Result<R>
1878    where
1879        T: 'static,
1880    {
1881        let entity = self.entities.read(handle);
1882        read(entity, self)
1883    }
1884
1885    fn update_window<T, F>(&mut self, handle: AnyWindowHandle, update: F) -> Result<T>
1886    where
1887        F: FnOnce(AnyView, &mut Window, &mut App) -> T,
1888    {
1889        self.update_window_id(handle.id, update)
1890    }
1891
1892    fn read_window<T, R>(
1893        &self,
1894        window: &WindowHandle<T>,
1895        read: impl FnOnce(Entity<T>, &App) -> R,
1896    ) -> Result<R>
1897    where
1898        T: 'static,
1899    {
1900        let window = self
1901            .windows
1902            .get(window.id)
1903            .context("window not found")?
1904            .as_ref()
1905            .expect("attempted to read a window that is already on the stack");
1906
1907        let root_view = window.root.clone().unwrap();
1908        let view = root_view
1909            .downcast::<T>()
1910            .map_err(|_| anyhow!("root view's type has changed"))?;
1911
1912        Ok(read(view, self))
1913    }
1914
1915    fn background_spawn<R>(&self, future: impl Future<Output = R> + Send + 'static) -> Task<R>
1916    where
1917        R: Send + 'static,
1918    {
1919        self.background_executor.spawn(future)
1920    }
1921
1922    fn read_global<G, R>(&self, callback: impl FnOnce(&G, &App) -> R) -> Self::Result<R>
1923    where
1924        G: Global,
1925    {
1926        let mut g = self.global::<G>();
1927        callback(g, self)
1928    }
1929}
1930
1931/// These effects are processed at the end of each application update cycle.
1932pub(crate) enum Effect {
1933    Notify {
1934        emitter: EntityId,
1935    },
1936    Emit {
1937        emitter: EntityId,
1938        event_type: TypeId,
1939        event: Box<dyn Any>,
1940    },
1941    RefreshWindows,
1942    NotifyGlobalObservers {
1943        global_type: TypeId,
1944    },
1945    Defer {
1946        callback: Box<dyn FnOnce(&mut App) + 'static>,
1947    },
1948    EntityCreated {
1949        entity: AnyEntity,
1950        tid: TypeId,
1951        window: Option<WindowId>,
1952    },
1953}
1954
1955impl std::fmt::Debug for Effect {
1956    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
1957        match self {
1958            Effect::Notify { emitter } => write!(f, "Notify({})", emitter),
1959            Effect::Emit { emitter, .. } => write!(f, "Emit({:?})", emitter),
1960            Effect::RefreshWindows => write!(f, "RefreshWindows"),
1961            Effect::NotifyGlobalObservers { global_type } => {
1962                write!(f, "NotifyGlobalObservers({:?})", global_type)
1963            }
1964            Effect::Defer { .. } => write!(f, "Defer(..)"),
1965            Effect::EntityCreated { entity, .. } => write!(f, "EntityCreated({:?})", entity),
1966        }
1967    }
1968}
1969
1970/// Wraps a global variable value during `update_global` while the value has been moved to the stack.
1971pub(crate) struct GlobalLease<G: Global> {
1972    global: Box<dyn Any>,
1973    global_type: PhantomData<G>,
1974}
1975
1976impl<G: Global> GlobalLease<G> {
1977    fn new(global: Box<dyn Any>) -> Self {
1978        GlobalLease {
1979            global,
1980            global_type: PhantomData,
1981        }
1982    }
1983}
1984
1985impl<G: Global> Deref for GlobalLease<G> {
1986    type Target = G;
1987
1988    fn deref(&self) -> &Self::Target {
1989        self.global.downcast_ref().unwrap()
1990    }
1991}
1992
1993impl<G: Global> DerefMut for GlobalLease<G> {
1994    fn deref_mut(&mut self) -> &mut Self::Target {
1995        self.global.downcast_mut().unwrap()
1996    }
1997}
1998
1999/// Contains state associated with an active drag operation, started by dragging an element
2000/// within the window or by dragging into the app from the underlying platform.
2001pub struct AnyDrag {
2002    /// The view used to render this drag
2003    pub view: AnyView,
2004
2005    /// The value of the dragged item, to be dropped
2006    pub value: Arc<dyn Any>,
2007
2008    /// This is used to render the dragged item in the same place
2009    /// on the original element that the drag was initiated
2010    pub cursor_offset: Point<Pixels>,
2011
2012    /// The cursor style to use while dragging
2013    pub cursor_style: Option<CursorStyle>,
2014}
2015
2016/// Contains state associated with a tooltip. You'll only need this struct if you're implementing
2017/// tooltip behavior on a custom element. Otherwise, use [Div::tooltip].
2018#[derive(Clone)]
2019pub struct AnyTooltip {
2020    /// The view used to display the tooltip
2021    pub view: AnyView,
2022
2023    /// The absolute position of the mouse when the tooltip was deployed.
2024    pub mouse_position: Point<Pixels>,
2025
2026    /// Given the bounds of the tooltip, checks whether the tooltip should still be visible and
2027    /// updates its state accordingly. This is needed atop the hovered element's mouse move handler
2028    /// to handle the case where the element is not painted (e.g. via use of `visible_on_hover`).
2029    pub check_visible_and_update: Rc<dyn Fn(Bounds<Pixels>, &mut Window, &mut App) -> bool>,
2030}
2031
2032/// A keystroke event, and potentially the associated action
2033#[derive(Debug)]
2034pub struct KeystrokeEvent {
2035    /// The keystroke that occurred
2036    pub keystroke: Keystroke,
2037
2038    /// The action that was resolved for the keystroke, if any
2039    pub action: Option<Box<dyn Action>>,
2040
2041    /// The context stack at the time
2042    pub context_stack: Vec<KeyContext>,
2043}
2044
2045struct NullHttpClient;
2046
2047impl HttpClient for NullHttpClient {
2048    fn send(
2049        &self,
2050        _req: http_client::Request<http_client::AsyncBody>,
2051    ) -> futures::future::BoxFuture<
2052        'static,
2053        anyhow::Result<http_client::Response<http_client::AsyncBody>>,
2054    > {
2055        async move {
2056            anyhow::bail!("No HttpClient available");
2057        }
2058        .boxed()
2059    }
2060
2061    fn user_agent(&self) -> Option<&http_client::http::HeaderValue> {
2062        None
2063    }
2064
2065    fn proxy(&self) -> Option<&Url> {
2066        None
2067    }
2068
2069    fn type_name(&self) -> &'static str {
2070        type_name::<Self>()
2071    }
2072}
2073
2074/// A mutable reference to an entity owned by GPUI
2075pub struct GpuiBorrow<'a, T> {
2076    inner: Option<Lease<T>>,
2077    app: &'a mut App,
2078}
2079
2080impl<'a, T: 'static> GpuiBorrow<'a, T> {
2081    fn new(inner: Entity<T>, app: &'a mut App) -> Self {
2082        app.start_update();
2083        let lease = app.entities.lease(&inner);
2084        Self {
2085            inner: Some(lease),
2086            app,
2087        }
2088    }
2089}
2090
2091impl<'a, T: 'static> std::borrow::Borrow<T> for GpuiBorrow<'a, T> {
2092    fn borrow(&self) -> &T {
2093        self.inner.as_ref().unwrap().borrow()
2094    }
2095}
2096
2097impl<'a, T: 'static> std::borrow::BorrowMut<T> for GpuiBorrow<'a, T> {
2098    fn borrow_mut(&mut self) -> &mut T {
2099        self.inner.as_mut().unwrap().borrow_mut()
2100    }
2101}
2102
2103impl<'a, T> Drop for GpuiBorrow<'a, T> {
2104    fn drop(&mut self) {
2105        let lease = self.inner.take().unwrap();
2106        self.app.notify(lease.id);
2107        self.app.entities.end_lease(lease);
2108        self.app.finish_update();
2109    }
2110}
2111
2112#[cfg(test)]
2113mod test {
2114    use std::{cell::RefCell, rc::Rc};
2115
2116    use crate::{AppContext, TestAppContext};
2117
2118    #[test]
2119    fn test_gpui_borrow() {
2120        let cx = TestAppContext::single();
2121        let observation_count = Rc::new(RefCell::new(0));
2122
2123        let state = cx.update(|cx| {
2124            let state = cx.new(|_| false);
2125            cx.observe(&state, {
2126                let observation_count = observation_count.clone();
2127                move |_, _| {
2128                    let mut count = observation_count.borrow_mut();
2129                    *count += 1;
2130                }
2131            })
2132            .detach();
2133
2134            state
2135        });
2136
2137        cx.update(|cx| {
2138            // Calling this like this so that we don't clobber the borrow_mut above
2139            *std::borrow::BorrowMut::borrow_mut(&mut state.as_mut(cx)) = true;
2140        });
2141
2142        cx.update(|cx| {
2143            state.write(cx, false);
2144        });
2145
2146        assert_eq!(*observation_count.borrow(), 2);
2147    }
2148}