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