app.rs

   1use std::{
   2    any::{type_name, TypeId},
   3    cell::{Ref, RefCell, RefMut},
   4    marker::PhantomData,
   5    ops::{Deref, DerefMut},
   6    path::{Path, PathBuf},
   7    rc::{Rc, Weak},
   8    sync::{atomic::Ordering::SeqCst, Arc},
   9    time::Duration,
  10};
  11
  12use anyhow::{anyhow, Result};
  13use derive_more::{Deref, DerefMut};
  14use futures::{channel::oneshot, future::LocalBoxFuture, Future};
  15use slotmap::SlotMap;
  16use smol::future::FutureExt;
  17use time::UtcOffset;
  18
  19pub use async_context::*;
  20use collections::{FxHashMap, FxHashSet, VecDeque};
  21pub use entity_map::*;
  22pub use model_context::*;
  23#[cfg(any(test, feature = "test-support"))]
  24pub use test_context::*;
  25use util::{
  26    http::{self, HttpClient},
  27    ResultExt,
  28};
  29
  30use crate::{
  31    current_platform, image_cache::ImageCache, init_app_menus, Action, ActionRegistry, Any,
  32    AnyView, AnyWindowHandle, AppMetadata, AssetSource, BackgroundExecutor, ClipboardItem, Context,
  33    DispatchPhase, DisplayId, Entity, EventEmitter, ForegroundExecutor, Global, KeyBinding, Keymap,
  34    Keystroke, LayoutId, Menu, PathPromptOptions, Pixels, Platform, PlatformDisplay, Point,
  35    PromptBuilder, PromptHandle, PromptLevel, Render, RenderablePromptHandle, SharedString,
  36    SubscriberSet, Subscription, SvgRenderer, Task, TextSystem, View, ViewContext, Window,
  37    WindowAppearance, WindowContext, WindowHandle, WindowId,
  38};
  39
  40mod async_context;
  41mod entity_map;
  42mod model_context;
  43#[cfg(any(test, feature = "test-support"))]
  44mod test_context;
  45
  46/// The duration for which futures returned from [AppContext::on_app_context] or [ModelContext::on_app_quit] can run before the application fully quits.
  47pub const SHUTDOWN_TIMEOUT: Duration = Duration::from_millis(100);
  48
  49/// Temporary(?) wrapper around [`RefCell<AppContext>`] to help us debug any double borrows.
  50/// Strongly consider removing after stabilization.
  51#[doc(hidden)]
  52pub struct AppCell {
  53    app: RefCell<AppContext>,
  54}
  55
  56impl AppCell {
  57    #[doc(hidden)]
  58    #[track_caller]
  59    pub fn borrow(&self) -> AppRef {
  60        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  61            let thread_id = std::thread::current().id();
  62            eprintln!("borrowed {thread_id:?}");
  63        }
  64        AppRef(self.app.borrow())
  65    }
  66
  67    #[doc(hidden)]
  68    #[track_caller]
  69    pub fn borrow_mut(&self) -> AppRefMut {
  70        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  71            let thread_id = std::thread::current().id();
  72            eprintln!("borrowed {thread_id:?}");
  73        }
  74        AppRefMut(self.app.borrow_mut())
  75    }
  76}
  77
  78#[doc(hidden)]
  79#[derive(Deref, DerefMut)]
  80pub struct AppRef<'a>(Ref<'a, AppContext>);
  81
  82impl<'a> Drop for AppRef<'a> {
  83    fn drop(&mut self) {
  84        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  85            let thread_id = std::thread::current().id();
  86            eprintln!("dropped borrow from {thread_id:?}");
  87        }
  88    }
  89}
  90
  91#[doc(hidden)]
  92#[derive(Deref, DerefMut)]
  93pub struct AppRefMut<'a>(RefMut<'a, AppContext>);
  94
  95impl<'a> Drop for AppRefMut<'a> {
  96    fn drop(&mut self) {
  97        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  98            let thread_id = std::thread::current().id();
  99            eprintln!("dropped {thread_id:?}");
 100        }
 101    }
 102}
 103
 104/// A reference to a GPUI application, typically constructed in the `main` function of your app.
 105/// You won't interact with this type much outside of initial configuration and startup.
 106pub struct App(Rc<AppCell>);
 107
 108/// Represents an application before it is fully launched. Once your app is
 109/// configured, you'll start the app with `App::run`.
 110impl App {
 111    /// Builds an app with the given asset source.
 112    #[allow(clippy::new_without_default)]
 113    pub fn new() -> Self {
 114        #[cfg(any(test, feature = "test-support"))]
 115        log::info!("GPUI was compiled in test mode");
 116
 117        Self(AppContext::new(
 118            current_platform(),
 119            Arc::new(()),
 120            http::client(),
 121        ))
 122    }
 123
 124    /// Assign
 125    pub fn with_assets(self, asset_source: impl AssetSource) -> Self {
 126        let mut context_lock = self.0.borrow_mut();
 127        let asset_source = Arc::new(asset_source);
 128        context_lock.asset_source = asset_source.clone();
 129        context_lock.svg_renderer = SvgRenderer::new(asset_source);
 130        drop(context_lock);
 131        self
 132    }
 133
 134    /// Start the application. The provided callback will be called once the
 135    /// app is fully launched.
 136    pub fn run<F>(self, on_finish_launching: F)
 137    where
 138        F: 'static + FnOnce(&mut AppContext),
 139    {
 140        let this = self.0.clone();
 141        let platform = self.0.borrow().platform.clone();
 142        platform.run(Box::new(move || {
 143            let cx = &mut *this.borrow_mut();
 144            on_finish_launching(cx);
 145        }));
 146    }
 147
 148    /// Register a handler to be invoked when the platform instructs the application
 149    /// to open one or more URLs.
 150    pub fn on_open_urls<F>(&self, mut callback: F) -> &Self
 151    where
 152        F: 'static + FnMut(Vec<String>),
 153    {
 154        self.0.borrow().platform.on_open_urls(Box::new(callback));
 155        self
 156    }
 157
 158    /// Invokes a handler when an already-running application is launched.
 159    /// On macOS, this can occur when the application icon is double-clicked or the app is launched via the dock.
 160    pub fn on_reopen<F>(&self, mut callback: F) -> &Self
 161    where
 162        F: 'static + FnMut(&mut AppContext),
 163    {
 164        let this = Rc::downgrade(&self.0);
 165        self.0.borrow_mut().platform.on_reopen(Box::new(move || {
 166            if let Some(app) = this.upgrade() {
 167                callback(&mut app.borrow_mut());
 168            }
 169        }));
 170        self
 171    }
 172
 173    /// Returns metadata associated with the application
 174    pub fn metadata(&self) -> AppMetadata {
 175        self.0.borrow().app_metadata.clone()
 176    }
 177
 178    /// Returns a handle to the [`BackgroundExecutor`] associated with this app, which can be used to spawn futures in the background.
 179    pub fn background_executor(&self) -> BackgroundExecutor {
 180        self.0.borrow().background_executor.clone()
 181    }
 182
 183    /// Returns a handle to the [`ForegroundExecutor`] associated with this app, which can be used to spawn futures in the foreground.
 184    pub fn foreground_executor(&self) -> ForegroundExecutor {
 185        self.0.borrow().foreground_executor.clone()
 186    }
 187
 188    /// Returns a reference to the [`TextSystem`] associated with this app.
 189    pub fn text_system(&self) -> Arc<TextSystem> {
 190        self.0.borrow().text_system.clone()
 191    }
 192
 193    /// Returns the file URL of the executable with the specified name in the application bundle
 194    pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
 195        self.0.borrow().path_for_auxiliary_executable(name)
 196    }
 197}
 198
 199type Handler = Box<dyn FnMut(&mut AppContext) -> bool + 'static>;
 200type Listener = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool + 'static>;
 201type KeystrokeObserver = Box<dyn FnMut(&KeystrokeEvent, &mut WindowContext) + 'static>;
 202type QuitHandler = Box<dyn FnOnce(&mut AppContext) -> LocalBoxFuture<'static, ()> + 'static>;
 203type ReleaseListener = Box<dyn FnOnce(&mut dyn Any, &mut AppContext) + 'static>;
 204type NewViewListener = Box<dyn FnMut(AnyView, &mut WindowContext) + 'static>;
 205
 206/// Contains the state of the full application, and passed as a reference to a variety of callbacks.
 207/// Other contexts such as [ModelContext], [WindowContext], and [ViewContext] deref to this type, making it the most general context type.
 208/// You need a reference to an `AppContext` to access the state of a [Model].
 209pub struct AppContext {
 210    pub(crate) this: Weak<AppCell>,
 211    pub(crate) platform: Rc<dyn Platform>,
 212    app_metadata: AppMetadata,
 213    text_system: Arc<TextSystem>,
 214    flushing_effects: bool,
 215    pending_updates: usize,
 216    pub(crate) actions: Rc<ActionRegistry>,
 217    pub(crate) active_drag: Option<AnyDrag>,
 218    pub(crate) background_executor: BackgroundExecutor,
 219    pub(crate) foreground_executor: ForegroundExecutor,
 220    pub(crate) svg_renderer: SvgRenderer,
 221    asset_source: Arc<dyn AssetSource>,
 222    pub(crate) image_cache: ImageCache,
 223    pub(crate) globals_by_type: FxHashMap<TypeId, Box<dyn Any>>,
 224    pub(crate) entities: EntityMap,
 225    pub(crate) new_view_observers: SubscriberSet<TypeId, NewViewListener>,
 226    pub(crate) windows: SlotMap<WindowId, Option<Window>>,
 227    pub(crate) window_handles: FxHashMap<WindowId, AnyWindowHandle>,
 228    pub(crate) keymap: Rc<RefCell<Keymap>>,
 229    pub(crate) global_action_listeners:
 230        FxHashMap<TypeId, Vec<Rc<dyn Fn(&dyn Any, DispatchPhase, &mut Self)>>>,
 231    pending_effects: VecDeque<Effect>,
 232    pub(crate) pending_notifications: FxHashSet<EntityId>,
 233    pub(crate) pending_global_notifications: FxHashSet<TypeId>,
 234    pub(crate) observers: SubscriberSet<EntityId, Handler>,
 235    // TypeId is the type of the event that the listener callback expects
 236    pub(crate) event_listeners: SubscriberSet<EntityId, (TypeId, Listener)>,
 237    pub(crate) keystroke_observers: SubscriberSet<(), KeystrokeObserver>,
 238    pub(crate) release_listeners: SubscriberSet<EntityId, ReleaseListener>,
 239    pub(crate) global_observers: SubscriberSet<TypeId, Handler>,
 240    pub(crate) quit_observers: SubscriberSet<(), QuitHandler>,
 241    pub(crate) layout_id_buffer: Vec<LayoutId>, // We recycle this memory across layout requests.
 242    pub(crate) propagate_event: bool,
 243    pub(crate) prompt_builder: Option<PromptBuilder>,
 244}
 245
 246impl AppContext {
 247    #[allow(clippy::new_ret_no_self)]
 248    pub(crate) fn new(
 249        platform: Rc<dyn Platform>,
 250        asset_source: Arc<dyn AssetSource>,
 251        http_client: Arc<dyn HttpClient>,
 252    ) -> Rc<AppCell> {
 253        let executor = platform.background_executor();
 254        let foreground_executor = platform.foreground_executor();
 255        assert!(
 256            executor.is_main_thread(),
 257            "must construct App on main thread"
 258        );
 259
 260        let text_system = Arc::new(TextSystem::new(platform.text_system()));
 261        let entities = EntityMap::new();
 262
 263        let app_metadata = AppMetadata {
 264            os_name: platform.os_name(),
 265            os_version: platform.os_version().ok(),
 266            app_version: platform.app_version().ok(),
 267        };
 268
 269        let app = Rc::new_cyclic(|this| AppCell {
 270            app: RefCell::new(AppContext {
 271                this: this.clone(),
 272                platform: platform.clone(),
 273                app_metadata,
 274                text_system,
 275                actions: Rc::new(ActionRegistry::default()),
 276                flushing_effects: false,
 277                pending_updates: 0,
 278                active_drag: None,
 279                background_executor: executor,
 280                foreground_executor,
 281                svg_renderer: SvgRenderer::new(asset_source.clone()),
 282                asset_source,
 283                image_cache: ImageCache::new(http_client),
 284                globals_by_type: FxHashMap::default(),
 285                entities,
 286                new_view_observers: SubscriberSet::new(),
 287                window_handles: FxHashMap::default(),
 288                windows: SlotMap::with_key(),
 289                keymap: Rc::new(RefCell::new(Keymap::default())),
 290                global_action_listeners: FxHashMap::default(),
 291                pending_effects: VecDeque::new(),
 292                pending_notifications: FxHashSet::default(),
 293                pending_global_notifications: FxHashSet::default(),
 294                observers: SubscriberSet::new(),
 295                event_listeners: SubscriberSet::new(),
 296                release_listeners: SubscriberSet::new(),
 297                keystroke_observers: SubscriberSet::new(),
 298                global_observers: SubscriberSet::new(),
 299                quit_observers: SubscriberSet::new(),
 300                layout_id_buffer: Default::default(),
 301                propagate_event: true,
 302                prompt_builder: Some(PromptBuilder::Default),
 303            }),
 304        });
 305
 306        init_app_menus(platform.as_ref(), &mut app.borrow_mut());
 307
 308        platform.on_quit(Box::new({
 309            let cx = app.clone();
 310            move || {
 311                cx.borrow_mut().shutdown();
 312            }
 313        }));
 314
 315        app
 316    }
 317
 318    /// Quit the application gracefully. Handlers registered with [`ModelContext::on_app_quit`]
 319    /// will be given 100ms to complete before exiting.
 320    pub fn shutdown(&mut self) {
 321        let mut futures = Vec::new();
 322
 323        for observer in self.quit_observers.remove(&()) {
 324            futures.push(observer(self));
 325        }
 326
 327        self.windows.clear();
 328        self.window_handles.clear();
 329        self.flush_effects();
 330
 331        let futures = futures::future::join_all(futures);
 332        if self
 333            .background_executor
 334            .block_with_timeout(SHUTDOWN_TIMEOUT, futures)
 335            .is_err()
 336        {
 337            log::error!("timed out waiting on app_will_quit");
 338        }
 339    }
 340
 341    /// Gracefully quit the application via the platform's standard routine.
 342    pub fn quit(&mut self) {
 343        self.platform.quit();
 344    }
 345
 346    /// Get metadata about the app and platform.
 347    pub fn app_metadata(&self) -> AppMetadata {
 348        self.app_metadata.clone()
 349    }
 350
 351    /// Schedules all windows in the application to be redrawn. This can be called
 352    /// multiple times in an update cycle and still result in a single redraw.
 353    pub fn refresh(&mut self) {
 354        self.pending_effects.push_back(Effect::Refresh);
 355    }
 356
 357    pub(crate) fn update<R>(&mut self, update: impl FnOnce(&mut Self) -> R) -> R {
 358        self.pending_updates += 1;
 359        let result = update(self);
 360        if !self.flushing_effects && self.pending_updates == 1 {
 361            self.flushing_effects = true;
 362            self.flush_effects();
 363            self.flushing_effects = false;
 364        }
 365        self.pending_updates -= 1;
 366        result
 367    }
 368
 369    /// Arrange a callback to be invoked when the given model or view calls `notify` on its respective context.
 370    pub fn observe<W, E>(
 371        &mut self,
 372        entity: &E,
 373        mut on_notify: impl FnMut(E, &mut AppContext) + 'static,
 374    ) -> Subscription
 375    where
 376        W: 'static,
 377        E: Entity<W>,
 378    {
 379        self.observe_internal(entity, move |e, cx| {
 380            on_notify(e, cx);
 381            true
 382        })
 383    }
 384
 385    pub(crate) fn new_observer(&mut self, key: EntityId, value: Handler) -> Subscription {
 386        let (subscription, activate) = self.observers.insert(key, value);
 387        self.defer(move |_| activate());
 388        subscription
 389    }
 390    pub(crate) fn observe_internal<W, E>(
 391        &mut self,
 392        entity: &E,
 393        mut on_notify: impl FnMut(E, &mut AppContext) -> bool + 'static,
 394    ) -> Subscription
 395    where
 396        W: 'static,
 397        E: Entity<W>,
 398    {
 399        let entity_id = entity.entity_id();
 400        let handle = entity.downgrade();
 401        self.new_observer(
 402            entity_id,
 403            Box::new(move |cx| {
 404                if let Some(handle) = E::upgrade_from(&handle) {
 405                    on_notify(handle, cx)
 406                } else {
 407                    false
 408                }
 409            }),
 410        )
 411    }
 412
 413    /// Arrange for the given callback to be invoked whenever the given model or view emits an event of a given type.
 414    /// The callback is provided a handle to the emitting entity and a reference to the emitted event.
 415    pub fn subscribe<T, E, Event>(
 416        &mut self,
 417        entity: &E,
 418        mut on_event: impl FnMut(E, &Event, &mut AppContext) + 'static,
 419    ) -> Subscription
 420    where
 421        T: 'static + EventEmitter<Event>,
 422        E: Entity<T>,
 423        Event: 'static,
 424    {
 425        self.subscribe_internal(entity, move |entity, event, cx| {
 426            on_event(entity, event, cx);
 427            true
 428        })
 429    }
 430
 431    pub(crate) fn new_subscription(
 432        &mut self,
 433        key: EntityId,
 434        value: (TypeId, Listener),
 435    ) -> Subscription {
 436        let (subscription, activate) = self.event_listeners.insert(key, value);
 437        self.defer(move |_| activate());
 438        subscription
 439    }
 440    pub(crate) fn subscribe_internal<T, E, Evt>(
 441        &mut self,
 442        entity: &E,
 443        mut on_event: impl FnMut(E, &Evt, &mut AppContext) -> bool + 'static,
 444    ) -> Subscription
 445    where
 446        T: 'static + EventEmitter<Evt>,
 447        E: Entity<T>,
 448        Evt: 'static,
 449    {
 450        let entity_id = entity.entity_id();
 451        let entity = entity.downgrade();
 452        self.new_subscription(
 453            entity_id,
 454            (
 455                TypeId::of::<Evt>(),
 456                Box::new(move |event, cx| {
 457                    let event: &Evt = event.downcast_ref().expect("invalid event type");
 458                    if let Some(handle) = E::upgrade_from(&entity) {
 459                        on_event(handle, event, cx)
 460                    } else {
 461                        false
 462                    }
 463                }),
 464            ),
 465        )
 466    }
 467
 468    /// Returns handles to all open windows in the application.
 469    /// Each handle could be downcast to a handle typed for the root view of that window.
 470    /// To find all windows of a given type, you could filter on
 471    pub fn windows(&self) -> Vec<AnyWindowHandle> {
 472        self.windows
 473            .keys()
 474            .flat_map(|window_id| self.window_handles.get(&window_id).copied())
 475            .collect()
 476    }
 477
 478    /// Returns a handle to the window that is currently focused at the platform level, if one exists.
 479    pub fn active_window(&self) -> Option<AnyWindowHandle> {
 480        self.platform.active_window()
 481    }
 482
 483    /// Opens a new window with the given option and the root view returned by the given function.
 484    /// The function is invoked with a `WindowContext`, which can be used to interact with window-specific
 485    /// functionality.
 486    pub fn open_window<V: 'static + Render>(
 487        &mut self,
 488        options: crate::WindowOptions,
 489        build_root_view: impl FnOnce(&mut WindowContext) -> View<V>,
 490    ) -> WindowHandle<V> {
 491        self.update(|cx| {
 492            let id = cx.windows.insert(None);
 493            let handle = WindowHandle::new(id);
 494            let mut window = Window::new(handle.into(), options, cx);
 495            let root_view = build_root_view(&mut WindowContext::new(cx, &mut window));
 496            window.root_view.replace(root_view.into());
 497            cx.window_handles.insert(id, window.handle);
 498            cx.windows.get_mut(id).unwrap().replace(window);
 499            handle
 500        })
 501    }
 502
 503    /// Instructs the platform to activate the application by bringing it to the foreground.
 504    pub fn activate(&self, ignoring_other_apps: bool) {
 505        self.platform.activate(ignoring_other_apps);
 506    }
 507
 508    /// Hide the application at the platform level.
 509    pub fn hide(&self) {
 510        self.platform.hide();
 511    }
 512
 513    /// Hide other applications at the platform level.
 514    pub fn hide_other_apps(&self) {
 515        self.platform.hide_other_apps();
 516    }
 517
 518    /// Unhide other applications at the platform level.
 519    pub fn unhide_other_apps(&self) {
 520        self.platform.unhide_other_apps();
 521    }
 522
 523    /// Returns the list of currently active displays.
 524    pub fn displays(&self) -> Vec<Rc<dyn PlatformDisplay>> {
 525        self.platform.displays()
 526    }
 527
 528    /// Returns the primary display that will be used for new windows.
 529    pub fn primary_display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 530        self.platform.primary_display()
 531    }
 532
 533    /// Returns the display with the given ID, if one exists.
 534    pub fn find_display(&self, id: DisplayId) -> Option<Rc<dyn PlatformDisplay>> {
 535        self.displays()
 536            .iter()
 537            .find(|display| display.id() == id)
 538            .cloned()
 539    }
 540
 541    /// Returns the appearance of the application's windows.
 542    pub fn window_appearance(&self) -> WindowAppearance {
 543        self.platform.window_appearance()
 544    }
 545
 546    /// Writes data to the platform clipboard.
 547    pub fn write_to_clipboard(&self, item: ClipboardItem) {
 548        self.platform.write_to_clipboard(item)
 549    }
 550
 551    /// Reads data from the platform clipboard.
 552    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
 553        self.platform.read_from_clipboard()
 554    }
 555
 556    /// Writes credentials to the platform keychain.
 557    pub fn write_credentials(
 558        &self,
 559        url: &str,
 560        username: &str,
 561        password: &[u8],
 562    ) -> Task<Result<()>> {
 563        self.platform.write_credentials(url, username, password)
 564    }
 565
 566    /// Reads credentials from the platform keychain.
 567    pub fn read_credentials(&self, url: &str) -> Task<Result<Option<(String, Vec<u8>)>>> {
 568        self.platform.read_credentials(url)
 569    }
 570
 571    /// Deletes credentials from the platform keychain.
 572    pub fn delete_credentials(&self, url: &str) -> Task<Result<()>> {
 573        self.platform.delete_credentials(url)
 574    }
 575
 576    /// Directs the platform's default browser to open the given URL.
 577    pub fn open_url(&self, url: &str) {
 578        self.platform.open_url(url);
 579    }
 580
 581    /// register_url_scheme requests that the given scheme (e.g. `zed` for `zed://` urls)
 582    /// is opened by the current app.
 583    /// On some platforms (e.g. macOS) you may be able to register URL schemes as part of app
 584    /// distribution, but this method exists to let you register schemes at runtime.
 585    pub fn register_url_scheme(&self, scheme: &str) -> Task<Result<()>> {
 586        self.platform.register_url_scheme(scheme)
 587    }
 588
 589    /// Returns the full pathname of the current app bundle.
 590    /// If the app is not being run from a bundle, returns an error.
 591    pub fn app_path(&self) -> Result<PathBuf> {
 592        self.platform.app_path()
 593    }
 594
 595    /// Returns the file URL of the executable with the specified name in the application bundle
 596    pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
 597        self.platform.path_for_auxiliary_executable(name)
 598    }
 599
 600    /// Displays a platform modal for selecting paths.
 601    /// When one or more paths are selected, they'll be relayed asynchronously via the returned oneshot channel.
 602    /// If cancelled, a `None` will be relayed instead.
 603    pub fn prompt_for_paths(
 604        &self,
 605        options: PathPromptOptions,
 606    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
 607        self.platform.prompt_for_paths(options)
 608    }
 609
 610    /// Displays a platform modal for selecting a new path where a file can be saved.
 611    /// The provided directory will be used to set the initial location.
 612    /// When a path is selected, it is relayed asynchronously via the returned oneshot channel.
 613    /// If cancelled, a `None` will be relayed instead.
 614    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
 615        self.platform.prompt_for_new_path(directory)
 616    }
 617
 618    /// Reveals the specified path at the platform level, such as in Finder on macOS.
 619    pub fn reveal_path(&self, path: &Path) {
 620        self.platform.reveal_path(path)
 621    }
 622
 623    /// Returns whether the user has configured scrollbars to auto-hide at the platform level.
 624    pub fn should_auto_hide_scrollbars(&self) -> bool {
 625        self.platform.should_auto_hide_scrollbars()
 626    }
 627
 628    /// Restart the application.
 629    pub fn restart(&self) {
 630        self.platform.restart()
 631    }
 632
 633    /// Returns the local timezone at the platform level.
 634    pub fn local_timezone(&self) -> UtcOffset {
 635        self.platform.local_timezone()
 636    }
 637
 638    pub(crate) fn push_effect(&mut self, effect: Effect) {
 639        match &effect {
 640            Effect::Notify { emitter } => {
 641                if !self.pending_notifications.insert(*emitter) {
 642                    return;
 643                }
 644            }
 645            Effect::NotifyGlobalObservers { global_type } => {
 646                if !self.pending_global_notifications.insert(*global_type) {
 647                    return;
 648                }
 649            }
 650            _ => {}
 651        };
 652
 653        self.pending_effects.push_back(effect);
 654    }
 655
 656    /// Called at the end of [`AppContext::update`] to complete any side effects
 657    /// such as notifying observers, emitting events, etc. Effects can themselves
 658    /// cause effects, so we continue looping until all effects are processed.
 659    fn flush_effects(&mut self) {
 660        loop {
 661            self.release_dropped_entities();
 662            self.release_dropped_focus_handles();
 663
 664            if let Some(effect) = self.pending_effects.pop_front() {
 665                match effect {
 666                    Effect::Notify { emitter } => {
 667                        self.apply_notify_effect(emitter);
 668                    }
 669
 670                    Effect::Emit {
 671                        emitter,
 672                        event_type,
 673                        event,
 674                    } => self.apply_emit_effect(emitter, event_type, event),
 675
 676                    Effect::Refresh => {
 677                        self.apply_refresh_effect();
 678                    }
 679
 680                    Effect::NotifyGlobalObservers { global_type } => {
 681                        self.apply_notify_global_observers_effect(global_type);
 682                    }
 683
 684                    Effect::Defer { callback } => {
 685                        self.apply_defer_effect(callback);
 686                    }
 687                }
 688            } else {
 689                #[cfg(any(test, feature = "test-support"))]
 690                for window in self
 691                    .windows
 692                    .values()
 693                    .filter_map(|window| {
 694                        let window = window.as_ref()?;
 695                        window.dirty.get().then_some(window.handle)
 696                    })
 697                    .collect::<Vec<_>>()
 698                {
 699                    self.update_window(window, |_, cx| cx.draw()).unwrap();
 700                }
 701
 702                if self.pending_effects.is_empty() {
 703                    break;
 704                }
 705            }
 706        }
 707    }
 708
 709    /// Repeatedly called during `flush_effects` to release any entities whose
 710    /// reference count has become zero. We invoke any release observers before dropping
 711    /// each entity.
 712    fn release_dropped_entities(&mut self) {
 713        loop {
 714            let dropped = self.entities.take_dropped();
 715            if dropped.is_empty() {
 716                break;
 717            }
 718
 719            for (entity_id, mut entity) in dropped {
 720                self.observers.remove(&entity_id);
 721                self.event_listeners.remove(&entity_id);
 722                for release_callback in self.release_listeners.remove(&entity_id) {
 723                    release_callback(entity.as_mut(), self);
 724                }
 725            }
 726        }
 727    }
 728
 729    /// Repeatedly called during `flush_effects` to handle a focused handle being dropped.
 730    fn release_dropped_focus_handles(&mut self) {
 731        for window_handle in self.windows() {
 732            window_handle
 733                .update(self, |_, cx| {
 734                    let mut blur_window = false;
 735                    let focus = cx.window.focus;
 736                    cx.window.focus_handles.write().retain(|handle_id, count| {
 737                        if count.load(SeqCst) == 0 {
 738                            if focus == Some(handle_id) {
 739                                blur_window = true;
 740                            }
 741                            false
 742                        } else {
 743                            true
 744                        }
 745                    });
 746
 747                    if blur_window {
 748                        cx.blur();
 749                    }
 750                })
 751                .unwrap();
 752        }
 753    }
 754
 755    fn apply_notify_effect(&mut self, emitter: EntityId) {
 756        self.pending_notifications.remove(&emitter);
 757
 758        self.observers
 759            .clone()
 760            .retain(&emitter, |handler| handler(self));
 761    }
 762
 763    fn apply_emit_effect(&mut self, emitter: EntityId, event_type: TypeId, event: Box<dyn Any>) {
 764        self.event_listeners
 765            .clone()
 766            .retain(&emitter, |(stored_type, handler)| {
 767                if *stored_type == event_type {
 768                    handler(event.as_ref(), self)
 769                } else {
 770                    true
 771                }
 772            });
 773    }
 774
 775    fn apply_refresh_effect(&mut self) {
 776        for window in self.windows.values_mut() {
 777            if let Some(window) = window.as_mut() {
 778                window.dirty.set(true);
 779            }
 780        }
 781    }
 782
 783    fn apply_notify_global_observers_effect(&mut self, type_id: TypeId) {
 784        self.pending_global_notifications.remove(&type_id);
 785        self.global_observers
 786            .clone()
 787            .retain(&type_id, |observer| observer(self));
 788    }
 789
 790    fn apply_defer_effect(&mut self, callback: Box<dyn FnOnce(&mut Self) + 'static>) {
 791        callback(self);
 792    }
 793
 794    /// Creates an `AsyncAppContext`, which can be cloned and has a static lifetime
 795    /// so it can be held across `await` points.
 796    pub fn to_async(&self) -> AsyncAppContext {
 797        AsyncAppContext {
 798            app: self.this.clone(),
 799            background_executor: self.background_executor.clone(),
 800            foreground_executor: self.foreground_executor.clone(),
 801        }
 802    }
 803
 804    /// Obtains a reference to the executor, which can be used to spawn futures.
 805    pub fn background_executor(&self) -> &BackgroundExecutor {
 806        &self.background_executor
 807    }
 808
 809    /// Obtains a reference to the executor, which can be used to spawn futures.
 810    pub fn foreground_executor(&self) -> &ForegroundExecutor {
 811        &self.foreground_executor
 812    }
 813
 814    /// Spawns the future returned by the given function on the thread pool. The closure will be invoked
 815    /// with [AsyncAppContext], which allows the application state to be accessed across await points.
 816    pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut) -> Task<R>
 817    where
 818        Fut: Future<Output = R> + 'static,
 819        R: 'static,
 820    {
 821        self.foreground_executor.spawn(f(self.to_async()))
 822    }
 823
 824    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 825    /// that are currently on the stack to be returned to the app.
 826    pub fn defer(&mut self, f: impl FnOnce(&mut AppContext) + 'static) {
 827        self.push_effect(Effect::Defer {
 828            callback: Box::new(f),
 829        });
 830    }
 831
 832    /// Accessor for the application's asset source, which is provided when constructing the `App`.
 833    pub fn asset_source(&self) -> &Arc<dyn AssetSource> {
 834        &self.asset_source
 835    }
 836
 837    /// Accessor for the text system.
 838    pub fn text_system(&self) -> &Arc<TextSystem> {
 839        &self.text_system
 840    }
 841
 842    /// Check whether a global of the given type has been assigned.
 843    pub fn has_global<G: Global>(&self) -> bool {
 844        self.globals_by_type.contains_key(&TypeId::of::<G>())
 845    }
 846
 847    /// Access the global of the given type. Panics if a global for that type has not been assigned.
 848    #[track_caller]
 849    pub fn global<G: Global>(&self) -> &G {
 850        self.globals_by_type
 851            .get(&TypeId::of::<G>())
 852            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
 853            .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
 854            .unwrap()
 855    }
 856
 857    /// Access the global of the given type if a value has been assigned.
 858    pub fn try_global<G: Global>(&self) -> Option<&G> {
 859        self.globals_by_type
 860            .get(&TypeId::of::<G>())
 861            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
 862    }
 863
 864    /// Access the global of the given type mutably. Panics if a global for that type has not been assigned.
 865    #[track_caller]
 866    pub fn global_mut<G: Global>(&mut self) -> &mut G {
 867        let global_type = TypeId::of::<G>();
 868        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 869        self.globals_by_type
 870            .get_mut(&global_type)
 871            .and_then(|any_state| any_state.downcast_mut::<G>())
 872            .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
 873            .unwrap()
 874    }
 875
 876    /// Access the global of the given type mutably. A default value is assigned if a global of this type has not
 877    /// yet been assigned.
 878    pub fn default_global<G: Global + Default>(&mut self) -> &mut G {
 879        let global_type = TypeId::of::<G>();
 880        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 881        self.globals_by_type
 882            .entry(global_type)
 883            .or_insert_with(|| Box::<G>::default())
 884            .downcast_mut::<G>()
 885            .unwrap()
 886    }
 887
 888    /// Sets the value of the global of the given type.
 889    pub fn set_global<G: Global>(&mut self, global: G) {
 890        let global_type = TypeId::of::<G>();
 891        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 892        self.globals_by_type.insert(global_type, Box::new(global));
 893    }
 894
 895    /// Clear all stored globals. Does not notify global observers.
 896    #[cfg(any(test, feature = "test-support"))]
 897    pub fn clear_globals(&mut self) {
 898        self.globals_by_type.drain();
 899    }
 900
 901    /// Remove the global of the given type from the app context. Does not notify global observers.
 902    pub fn remove_global<G: Global>(&mut self) -> G {
 903        let global_type = TypeId::of::<G>();
 904        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 905        *self
 906            .globals_by_type
 907            .remove(&global_type)
 908            .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<G>()))
 909            .downcast()
 910            .unwrap()
 911    }
 912
 913    /// Register a callback to be invoked when a global of the given type is updated.
 914    pub fn observe_global<G: Global>(
 915        &mut self,
 916        mut f: impl FnMut(&mut Self) + 'static,
 917    ) -> Subscription {
 918        let (subscription, activate) = self.global_observers.insert(
 919            TypeId::of::<G>(),
 920            Box::new(move |cx| {
 921                f(cx);
 922                true
 923            }),
 924        );
 925        self.defer(move |_| activate());
 926        subscription
 927    }
 928
 929    /// Move the global of the given type to the stack.
 930    pub(crate) fn lease_global<G: Global>(&mut self) -> GlobalLease<G> {
 931        GlobalLease::new(
 932            self.globals_by_type
 933                .remove(&TypeId::of::<G>())
 934                .ok_or_else(|| anyhow!("no global registered of type {}", type_name::<G>()))
 935                .unwrap(),
 936        )
 937    }
 938
 939    /// Restore the global of the given type after it is moved to the stack.
 940    pub(crate) fn end_global_lease<G: Global>(&mut self, lease: GlobalLease<G>) {
 941        let global_type = TypeId::of::<G>();
 942        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 943        self.globals_by_type.insert(global_type, lease.global);
 944    }
 945
 946    pub(crate) fn new_view_observer(
 947        &mut self,
 948        key: TypeId,
 949        value: NewViewListener,
 950    ) -> Subscription {
 951        let (subscription, activate) = self.new_view_observers.insert(key, value);
 952        activate();
 953        subscription
 954    }
 955    /// Arrange for the given function to be invoked whenever a view of the specified type is created.
 956    /// The function will be passed a mutable reference to the view along with an appropriate context.
 957    pub fn observe_new_views<V: 'static>(
 958        &mut self,
 959        on_new: impl 'static + Fn(&mut V, &mut ViewContext<V>),
 960    ) -> Subscription {
 961        self.new_view_observer(
 962            TypeId::of::<V>(),
 963            Box::new(move |any_view: AnyView, cx: &mut WindowContext| {
 964                any_view
 965                    .downcast::<V>()
 966                    .unwrap()
 967                    .update(cx, |view_state, cx| {
 968                        on_new(view_state, cx);
 969                    })
 970            }),
 971        )
 972    }
 973
 974    /// Observe the release of a model or view. The callback is invoked after the model or view
 975    /// has no more strong references but before it has been dropped.
 976    pub fn observe_release<E, T>(
 977        &mut self,
 978        handle: &E,
 979        on_release: impl FnOnce(&mut T, &mut AppContext) + 'static,
 980    ) -> Subscription
 981    where
 982        E: Entity<T>,
 983        T: 'static,
 984    {
 985        let (subscription, activate) = self.release_listeners.insert(
 986            handle.entity_id(),
 987            Box::new(move |entity, cx| {
 988                let entity = entity.downcast_mut().expect("invalid entity type");
 989                on_release(entity, cx)
 990            }),
 991        );
 992        activate();
 993        subscription
 994    }
 995
 996    /// Register a callback to be invoked when a keystroke is received by the application
 997    /// in any window. Note that this fires after all other action and event mechanisms have resolved
 998    /// and that this API will not be invoked if the event's propagation is stopped.
 999    pub fn observe_keystrokes(
1000        &mut self,
1001        f: impl FnMut(&KeystrokeEvent, &mut WindowContext) + 'static,
1002    ) -> Subscription {
1003        fn inner(
1004            keystroke_observers: &mut SubscriberSet<(), KeystrokeObserver>,
1005            handler: KeystrokeObserver,
1006        ) -> Subscription {
1007            let (subscription, activate) = keystroke_observers.insert((), handler);
1008            activate();
1009            subscription
1010        }
1011        inner(&mut self.keystroke_observers, Box::new(f))
1012    }
1013
1014    /// Register key bindings.
1015    pub fn bind_keys(&mut self, bindings: impl IntoIterator<Item = KeyBinding>) {
1016        self.keymap.borrow_mut().add_bindings(bindings);
1017        self.pending_effects.push_back(Effect::Refresh);
1018    }
1019
1020    /// Clear all key bindings in the app.
1021    pub fn clear_key_bindings(&mut self) {
1022        self.keymap.borrow_mut().clear();
1023        self.pending_effects.push_back(Effect::Refresh);
1024    }
1025
1026    /// Register a global listener for actions invoked via the keyboard.
1027    pub fn on_action<A: Action>(&mut self, listener: impl Fn(&A, &mut Self) + 'static) {
1028        self.global_action_listeners
1029            .entry(TypeId::of::<A>())
1030            .or_default()
1031            .push(Rc::new(move |action, phase, cx| {
1032                if phase == DispatchPhase::Bubble {
1033                    let action = action.downcast_ref().unwrap();
1034                    listener(action, cx)
1035                }
1036            }));
1037    }
1038
1039    /// Event handlers propagate events by default. Call this method to stop dispatching to
1040    /// event handlers with a lower z-index (mouse) or higher in the tree (keyboard). This is
1041    /// the opposite of [`Self::propagate`]. It's also possible to cancel a call to [`Self::propagate`] by
1042    /// calling this method before effects are flushed.
1043    pub fn stop_propagation(&mut self) {
1044        self.propagate_event = false;
1045    }
1046
1047    /// Action handlers stop propagation by default during the bubble phase of action dispatch
1048    /// dispatching to action handlers higher in the element tree. This is the opposite of
1049    /// [`Self::stop_propagation`]. It's also possible to cancel a call to [`Self::stop_propagation`] by calling
1050    /// this method before effects are flushed.
1051    pub fn propagate(&mut self) {
1052        self.propagate_event = true;
1053    }
1054
1055    /// Build an action from some arbitrary data, typically a keymap entry.
1056    pub fn build_action(
1057        &self,
1058        name: &str,
1059        data: Option<serde_json::Value>,
1060    ) -> Result<Box<dyn Action>> {
1061        self.actions.build_action(name, data)
1062    }
1063
1064    /// Get a list of all action names that have been registered.
1065    /// in the application. Note that registration only allows for
1066    /// actions to be built dynamically, and is unrelated to binding
1067    /// actions in the element tree.
1068    pub fn all_action_names(&self) -> &[SharedString] {
1069        self.actions.all_action_names()
1070    }
1071
1072    /// Register a callback to be invoked when the application is about to quit.
1073    /// It is not possible to cancel the quit event at this point.
1074    pub fn on_app_quit<Fut>(
1075        &mut self,
1076        mut on_quit: impl FnMut(&mut AppContext) -> Fut + 'static,
1077    ) -> Subscription
1078    where
1079        Fut: 'static + Future<Output = ()>,
1080    {
1081        let (subscription, activate) = self.quit_observers.insert(
1082            (),
1083            Box::new(move |cx| {
1084                let future = on_quit(cx);
1085                future.boxed_local()
1086            }),
1087        );
1088        activate();
1089        subscription
1090    }
1091
1092    pub(crate) fn clear_pending_keystrokes(&mut self) {
1093        for window in self.windows() {
1094            window
1095                .update(self, |_, cx| {
1096                    cx.window
1097                        .rendered_frame
1098                        .dispatch_tree
1099                        .clear_pending_keystrokes();
1100                    cx.window
1101                        .next_frame
1102                        .dispatch_tree
1103                        .clear_pending_keystrokes();
1104                })
1105                .ok();
1106        }
1107    }
1108
1109    /// Checks if the given action is bound in the current context, as defined by the app's current focus,
1110    /// the bindings in the element tree, and any global action listeners.
1111    pub fn is_action_available(&mut self, action: &dyn Action) -> bool {
1112        let mut action_available = false;
1113        if let Some(window) = self.active_window() {
1114            if let Ok(window_action_available) =
1115                window.update(self, |_, cx| cx.is_action_available(action))
1116            {
1117                action_available = window_action_available;
1118            }
1119        }
1120
1121        action_available
1122            || self
1123                .global_action_listeners
1124                .contains_key(&action.as_any().type_id())
1125    }
1126
1127    /// Sets the menu bar for this application. This will replace any existing menu bar.
1128    pub fn set_menus(&mut self, menus: Vec<Menu>) {
1129        self.platform.set_menus(menus, &self.keymap.borrow());
1130    }
1131
1132    /// Adds given path to list of recent paths for the application.
1133    /// The list is usually shown on the application icon's context menu in the dock,
1134    /// and allows to open the recent files via that context menu.
1135    pub fn add_recent_documents(&mut self, paths: &[PathBuf]) {
1136        self.platform.add_recent_documents(paths);
1137    }
1138
1139    /// Clears the list of recent paths from the application.
1140    pub fn clear_recent_documents(&mut self) {
1141        self.platform.clear_recent_documents();
1142    }
1143    /// Dispatch an action to the currently active window or global action handler
1144    /// See [action::Action] for more information on how actions work
1145    pub fn dispatch_action(&mut self, action: &dyn Action) {
1146        if let Some(active_window) = self.active_window() {
1147            active_window
1148                .update(self, |_, cx| cx.dispatch_action(action.boxed_clone()))
1149                .log_err();
1150        } else {
1151            self.dispatch_global_action(action);
1152        }
1153    }
1154
1155    fn dispatch_global_action(&mut self, action: &dyn Action) {
1156        self.propagate_event = true;
1157
1158        if let Some(mut global_listeners) = self
1159            .global_action_listeners
1160            .remove(&action.as_any().type_id())
1161        {
1162            for listener in &global_listeners {
1163                listener(action.as_any(), DispatchPhase::Capture, self);
1164                if !self.propagate_event {
1165                    break;
1166                }
1167            }
1168
1169            global_listeners.extend(
1170                self.global_action_listeners
1171                    .remove(&action.as_any().type_id())
1172                    .unwrap_or_default(),
1173            );
1174
1175            self.global_action_listeners
1176                .insert(action.as_any().type_id(), global_listeners);
1177        }
1178
1179        if self.propagate_event {
1180            if let Some(mut global_listeners) = self
1181                .global_action_listeners
1182                .remove(&action.as_any().type_id())
1183            {
1184                for listener in global_listeners.iter().rev() {
1185                    listener(action.as_any(), DispatchPhase::Bubble, self);
1186                    if !self.propagate_event {
1187                        break;
1188                    }
1189                }
1190
1191                global_listeners.extend(
1192                    self.global_action_listeners
1193                        .remove(&action.as_any().type_id())
1194                        .unwrap_or_default(),
1195                );
1196
1197                self.global_action_listeners
1198                    .insert(action.as_any().type_id(), global_listeners);
1199            }
1200        }
1201    }
1202
1203    /// Is there currently something being dragged?
1204    pub fn has_active_drag(&self) -> bool {
1205        self.active_drag.is_some()
1206    }
1207
1208    /// Set the prompt renderer for GPUI. This will replace the default or platform specific
1209    /// prompts with this custom implementation.
1210    pub fn set_prompt_builder(
1211        &mut self,
1212        renderer: impl Fn(
1213                PromptLevel,
1214                &str,
1215                Option<&str>,
1216                &[&str],
1217                PromptHandle,
1218                &mut WindowContext,
1219            ) -> RenderablePromptHandle
1220            + 'static,
1221    ) {
1222        self.prompt_builder = Some(PromptBuilder::Custom(Box::new(renderer)))
1223    }
1224}
1225
1226impl Context for AppContext {
1227    type Result<T> = T;
1228
1229    /// Build an entity that is owned by the application. The given function will be invoked with
1230    /// a `ModelContext` and must return an object representing the entity. A `Model` handle will be returned,
1231    /// which can be used to access the entity in a context.
1232    fn new_model<T: 'static>(
1233        &mut self,
1234        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
1235    ) -> Model<T> {
1236        self.update(|cx| {
1237            let slot = cx.entities.reserve();
1238            let entity = build_model(&mut ModelContext::new(cx, slot.downgrade()));
1239            cx.entities.insert(slot, entity)
1240        })
1241    }
1242
1243    /// Updates the entity referenced by the given model. The function is passed a mutable reference to the
1244    /// entity along with a `ModelContext` for the entity.
1245    fn update_model<T: 'static, R>(
1246        &mut self,
1247        model: &Model<T>,
1248        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1249    ) -> R {
1250        self.update(|cx| {
1251            let mut entity = cx.entities.lease(model);
1252            let result = update(&mut entity, &mut ModelContext::new(cx, model.downgrade()));
1253            cx.entities.end_lease(entity);
1254            result
1255        })
1256    }
1257
1258    fn update_window<T, F>(&mut self, handle: AnyWindowHandle, update: F) -> Result<T>
1259    where
1260        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1261    {
1262        self.update(|cx| {
1263            let mut window = cx
1264                .windows
1265                .get_mut(handle.id)
1266                .ok_or_else(|| anyhow!("window not found"))?
1267                .take()
1268                .ok_or_else(|| anyhow!("window not found"))?;
1269
1270            let root_view = window.root_view.clone().unwrap();
1271            let result = update(root_view, &mut WindowContext::new(cx, &mut window));
1272
1273            if window.removed {
1274                cx.window_handles.remove(&handle.id);
1275                cx.windows.remove(handle.id);
1276            } else {
1277                cx.windows
1278                    .get_mut(handle.id)
1279                    .ok_or_else(|| anyhow!("window not found"))?
1280                    .replace(window);
1281            }
1282
1283            Ok(result)
1284        })
1285    }
1286
1287    fn read_model<T, R>(
1288        &self,
1289        handle: &Model<T>,
1290        read: impl FnOnce(&T, &AppContext) -> R,
1291    ) -> Self::Result<R>
1292    where
1293        T: 'static,
1294    {
1295        let entity = self.entities.read(handle);
1296        read(entity, self)
1297    }
1298
1299    fn read_window<T, R>(
1300        &self,
1301        window: &WindowHandle<T>,
1302        read: impl FnOnce(View<T>, &AppContext) -> R,
1303    ) -> Result<R>
1304    where
1305        T: 'static,
1306    {
1307        let window = self
1308            .windows
1309            .get(window.id)
1310            .ok_or_else(|| anyhow!("window not found"))?
1311            .as_ref()
1312            .unwrap();
1313
1314        let root_view = window.root_view.clone().unwrap();
1315        let view = root_view
1316            .downcast::<T>()
1317            .map_err(|_| anyhow!("root view's type has changed"))?;
1318
1319        Ok(read(view, self))
1320    }
1321}
1322
1323/// These effects are processed at the end of each application update cycle.
1324pub(crate) enum Effect {
1325    Notify {
1326        emitter: EntityId,
1327    },
1328    Emit {
1329        emitter: EntityId,
1330        event_type: TypeId,
1331        event: Box<dyn Any>,
1332    },
1333    Refresh,
1334    NotifyGlobalObservers {
1335        global_type: TypeId,
1336    },
1337    Defer {
1338        callback: Box<dyn FnOnce(&mut AppContext) + 'static>,
1339    },
1340}
1341
1342/// Wraps a global variable value during `update_global` while the value has been moved to the stack.
1343pub(crate) struct GlobalLease<G: Global> {
1344    global: Box<dyn Any>,
1345    global_type: PhantomData<G>,
1346}
1347
1348impl<G: Global> GlobalLease<G> {
1349    fn new(global: Box<dyn Any>) -> Self {
1350        GlobalLease {
1351            global,
1352            global_type: PhantomData,
1353        }
1354    }
1355}
1356
1357impl<G: Global> Deref for GlobalLease<G> {
1358    type Target = G;
1359
1360    fn deref(&self) -> &Self::Target {
1361        self.global.downcast_ref().unwrap()
1362    }
1363}
1364
1365impl<G: Global> DerefMut for GlobalLease<G> {
1366    fn deref_mut(&mut self) -> &mut Self::Target {
1367        self.global.downcast_mut().unwrap()
1368    }
1369}
1370
1371/// Contains state associated with an active drag operation, started by dragging an element
1372/// within the window or by dragging into the app from the underlying platform.
1373pub struct AnyDrag {
1374    /// The view used to render this drag
1375    pub view: AnyView,
1376
1377    /// The value of the dragged item, to be dropped
1378    pub value: Box<dyn Any>,
1379
1380    /// This is used to render the dragged item in the same place
1381    /// on the original element that the drag was initiated
1382    pub cursor_offset: Point<Pixels>,
1383}
1384
1385/// Contains state associated with a tooltip. You'll only need this struct if you're implementing
1386/// tooltip behavior on a custom element. Otherwise, use [Div::tooltip].
1387#[derive(Clone)]
1388pub struct AnyTooltip {
1389    /// The view used to display the tooltip
1390    pub view: AnyView,
1391
1392    /// The offset from the cursor to use, relative to the parent view
1393    pub cursor_offset: Point<Pixels>,
1394}
1395
1396/// A keystroke event, and potentially the associated action
1397#[derive(Debug)]
1398pub struct KeystrokeEvent {
1399    /// The keystroke that occurred
1400    pub keystroke: Keystroke,
1401
1402    /// The action that was resolved for the keystroke, if any
1403    pub action: Option<Box<dyn Action>>,
1404}