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::*;
  22use http::{self, HttpClient};
  23pub use model_context::*;
  24#[cfg(any(test, feature = "test-support"))]
  25pub use test_context::*;
  26use util::ResultExt;
  27
  28use crate::{
  29    current_platform, init_app_menus, Action, ActionRegistry, Any, AnyView, AnyWindowHandle,
  30    AssetCache, AssetSource, BackgroundExecutor, ClipboardItem, Context, DispatchPhase, DisplayId,
  31    Entity, EventEmitter, ForegroundExecutor, Global, KeyBinding, Keymap, Keystroke, LayoutId,
  32    Menu, MenuItem, OwnedMenu, PathPromptOptions, Pixels, Platform, PlatformDisplay, Point,
  33    PromptBuilder, PromptHandle, PromptLevel, Render, RenderablePromptHandle, Reservation,
  34    SharedString, SubscriberSet, Subscription, SvgRenderer, Task, TextSystem, View, ViewContext,
  35    Window, WindowAppearance, WindowContext, WindowHandle, WindowId,
  36};
  37
  38mod async_context;
  39mod entity_map;
  40mod model_context;
  41#[cfg(any(test, feature = "test-support"))]
  42mod test_context;
  43
  44/// The duration for which futures returned from [AppContext::on_app_context] or [ModelContext::on_app_quit] can run before the application fully quits.
  45pub const SHUTDOWN_TIMEOUT: Duration = Duration::from_millis(100);
  46
  47/// Temporary(?) wrapper around [`RefCell<AppContext>`] to help us debug any double borrows.
  48/// Strongly consider removing after stabilization.
  49#[doc(hidden)]
  50pub struct AppCell {
  51    app: RefCell<AppContext>,
  52}
  53
  54impl AppCell {
  55    #[doc(hidden)]
  56    #[track_caller]
  57    pub fn borrow(&self) -> AppRef {
  58        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  59            let thread_id = std::thread::current().id();
  60            eprintln!("borrowed {thread_id:?}");
  61        }
  62        AppRef(self.app.borrow())
  63    }
  64
  65    #[doc(hidden)]
  66    #[track_caller]
  67    pub fn borrow_mut(&self) -> AppRefMut {
  68        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  69            let thread_id = std::thread::current().id();
  70            eprintln!("borrowed {thread_id:?}");
  71        }
  72        AppRefMut(self.app.borrow_mut())
  73    }
  74}
  75
  76#[doc(hidden)]
  77#[derive(Deref, DerefMut)]
  78pub struct AppRef<'a>(Ref<'a, AppContext>);
  79
  80impl<'a> Drop for AppRef<'a> {
  81    fn drop(&mut self) {
  82        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  83            let thread_id = std::thread::current().id();
  84            eprintln!("dropped borrow from {thread_id:?}");
  85        }
  86    }
  87}
  88
  89#[doc(hidden)]
  90#[derive(Deref, DerefMut)]
  91pub struct AppRefMut<'a>(RefMut<'a, AppContext>);
  92
  93impl<'a> Drop for AppRefMut<'a> {
  94    fn drop(&mut self) {
  95        if option_env!("TRACK_THREAD_BORROWS").is_some() {
  96            let thread_id = std::thread::current().id();
  97            eprintln!("dropped {thread_id:?}");
  98        }
  99    }
 100}
 101
 102/// A reference to a GPUI application, typically constructed in the `main` function of your app.
 103/// You won't interact with this type much outside of initial configuration and startup.
 104pub struct App(Rc<AppCell>);
 105
 106/// Represents an application before it is fully launched. Once your app is
 107/// configured, you'll start the app with `App::run`.
 108impl App {
 109    /// Builds an app with the given asset source.
 110    #[allow(clippy::new_without_default)]
 111    pub fn new() -> Self {
 112        #[cfg(any(test, feature = "test-support"))]
 113        log::info!("GPUI was compiled in test mode");
 114
 115        Self(AppContext::new(
 116            current_platform(),
 117            Arc::new(()),
 118            http::client(None),
 119        ))
 120    }
 121
 122    /// Assign
 123    pub fn with_assets(self, asset_source: impl AssetSource) -> Self {
 124        let mut context_lock = self.0.borrow_mut();
 125        let asset_source = Arc::new(asset_source);
 126        context_lock.asset_source = asset_source.clone();
 127        context_lock.svg_renderer = SvgRenderer::new(asset_source);
 128        drop(context_lock);
 129        self
 130    }
 131
 132    /// Start the application. The provided callback will be called once the
 133    /// app is fully launched.
 134    pub fn run<F>(self, on_finish_launching: F)
 135    where
 136        F: 'static + FnOnce(&mut AppContext),
 137    {
 138        let this = self.0.clone();
 139        let platform = self.0.borrow().platform.clone();
 140        platform.run(Box::new(move || {
 141            let cx = &mut *this.borrow_mut();
 142            on_finish_launching(cx);
 143        }));
 144    }
 145
 146    /// Register a handler to be invoked when the platform instructs the application
 147    /// to open one or more URLs.
 148    pub fn on_open_urls<F>(&self, mut callback: F) -> &Self
 149    where
 150        F: 'static + FnMut(Vec<String>),
 151    {
 152        self.0.borrow().platform.on_open_urls(Box::new(callback));
 153        self
 154    }
 155
 156    /// Invokes a handler when an already-running application is launched.
 157    /// On macOS, this can occur when the application icon is double-clicked or the app is launched via the dock.
 158    pub fn on_reopen<F>(&self, mut callback: F) -> &Self
 159    where
 160        F: 'static + FnMut(&mut AppContext),
 161    {
 162        let this = Rc::downgrade(&self.0);
 163        self.0.borrow_mut().platform.on_reopen(Box::new(move || {
 164            if let Some(app) = this.upgrade() {
 165                callback(&mut app.borrow_mut());
 166            }
 167        }));
 168        self
 169    }
 170
 171    /// Returns a handle to the [`BackgroundExecutor`] associated with this app, which can be used to spawn futures in the background.
 172    pub fn background_executor(&self) -> BackgroundExecutor {
 173        self.0.borrow().background_executor.clone()
 174    }
 175
 176    /// Returns a handle to the [`ForegroundExecutor`] associated with this app, which can be used to spawn futures in the foreground.
 177    pub fn foreground_executor(&self) -> ForegroundExecutor {
 178        self.0.borrow().foreground_executor.clone()
 179    }
 180
 181    /// Returns a reference to the [`TextSystem`] associated with this app.
 182    pub fn text_system(&self) -> Arc<TextSystem> {
 183        self.0.borrow().text_system.clone()
 184    }
 185
 186    /// Returns the file URL of the executable with the specified name in the application bundle
 187    pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
 188        self.0.borrow().path_for_auxiliary_executable(name)
 189    }
 190}
 191
 192type Handler = Box<dyn FnMut(&mut AppContext) -> bool + 'static>;
 193type Listener = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool + 'static>;
 194type KeystrokeObserver = Box<dyn FnMut(&KeystrokeEvent, &mut WindowContext) + 'static>;
 195type QuitHandler = Box<dyn FnOnce(&mut AppContext) -> LocalBoxFuture<'static, ()> + 'static>;
 196type ReleaseListener = Box<dyn FnOnce(&mut dyn Any, &mut AppContext) + 'static>;
 197type NewViewListener = Box<dyn FnMut(AnyView, &mut WindowContext) + 'static>;
 198
 199/// Contains the state of the full application, and passed as a reference to a variety of callbacks.
 200/// Other contexts such as [ModelContext], [WindowContext], and [ViewContext] deref to this type, making it the most general context type.
 201/// You need a reference to an `AppContext` to access the state of a [Model].
 202pub struct AppContext {
 203    pub(crate) this: Weak<AppCell>,
 204    pub(crate) platform: Rc<dyn Platform>,
 205    text_system: Arc<TextSystem>,
 206    flushing_effects: bool,
 207    pending_updates: usize,
 208    pub(crate) actions: Rc<ActionRegistry>,
 209    pub(crate) active_drag: Option<AnyDrag>,
 210    pub(crate) background_executor: BackgroundExecutor,
 211    pub(crate) foreground_executor: ForegroundExecutor,
 212    pub(crate) loading_assets: FxHashMap<(TypeId, u64), Box<dyn Any>>,
 213    pub(crate) asset_cache: AssetCache,
 214    asset_source: Arc<dyn AssetSource>,
 215    pub(crate) svg_renderer: SvgRenderer,
 216    http_client: Arc<dyn HttpClient>,
 217    pub(crate) globals_by_type: FxHashMap<TypeId, Box<dyn Any>>,
 218    pub(crate) entities: EntityMap,
 219    pub(crate) new_view_observers: SubscriberSet<TypeId, NewViewListener>,
 220    pub(crate) windows: SlotMap<WindowId, Option<Window>>,
 221    pub(crate) window_handles: FxHashMap<WindowId, AnyWindowHandle>,
 222    pub(crate) keymap: Rc<RefCell<Keymap>>,
 223    pub(crate) global_action_listeners:
 224        FxHashMap<TypeId, Vec<Rc<dyn Fn(&dyn Any, DispatchPhase, &mut Self)>>>,
 225    pending_effects: VecDeque<Effect>,
 226    pub(crate) pending_notifications: FxHashSet<EntityId>,
 227    pub(crate) pending_global_notifications: FxHashSet<TypeId>,
 228    pub(crate) observers: SubscriberSet<EntityId, Handler>,
 229    // TypeId is the type of the event that the listener callback expects
 230    pub(crate) event_listeners: SubscriberSet<EntityId, (TypeId, Listener)>,
 231    pub(crate) keystroke_observers: SubscriberSet<(), KeystrokeObserver>,
 232    pub(crate) release_listeners: SubscriberSet<EntityId, ReleaseListener>,
 233    pub(crate) global_observers: SubscriberSet<TypeId, Handler>,
 234    pub(crate) quit_observers: SubscriberSet<(), QuitHandler>,
 235    pub(crate) layout_id_buffer: Vec<LayoutId>, // We recycle this memory across layout requests.
 236    pub(crate) propagate_event: bool,
 237    pub(crate) prompt_builder: Option<PromptBuilder>,
 238}
 239
 240impl AppContext {
 241    #[allow(clippy::new_ret_no_self)]
 242    pub(crate) fn new(
 243        platform: Rc<dyn Platform>,
 244        asset_source: Arc<dyn AssetSource>,
 245        http_client: Arc<dyn HttpClient>,
 246    ) -> Rc<AppCell> {
 247        let executor = platform.background_executor();
 248        let foreground_executor = platform.foreground_executor();
 249        assert!(
 250            executor.is_main_thread(),
 251            "must construct App on main thread"
 252        );
 253
 254        let text_system = Arc::new(TextSystem::new(platform.text_system()));
 255        let entities = EntityMap::new();
 256
 257        let app = Rc::new_cyclic(|this| AppCell {
 258            app: RefCell::new(AppContext {
 259                this: this.clone(),
 260                platform: platform.clone(),
 261                text_system,
 262                actions: Rc::new(ActionRegistry::default()),
 263                flushing_effects: false,
 264                pending_updates: 0,
 265                active_drag: None,
 266                background_executor: executor,
 267                foreground_executor,
 268                svg_renderer: SvgRenderer::new(asset_source.clone()),
 269                asset_cache: AssetCache::new(),
 270                loading_assets: Default::default(),
 271                asset_source,
 272                http_client,
 273                globals_by_type: FxHashMap::default(),
 274                entities,
 275                new_view_observers: SubscriberSet::new(),
 276                window_handles: FxHashMap::default(),
 277                windows: SlotMap::with_key(),
 278                keymap: Rc::new(RefCell::new(Keymap::default())),
 279                global_action_listeners: FxHashMap::default(),
 280                pending_effects: VecDeque::new(),
 281                pending_notifications: FxHashSet::default(),
 282                pending_global_notifications: FxHashSet::default(),
 283                observers: SubscriberSet::new(),
 284                event_listeners: SubscriberSet::new(),
 285                release_listeners: SubscriberSet::new(),
 286                keystroke_observers: SubscriberSet::new(),
 287                global_observers: SubscriberSet::new(),
 288                quit_observers: SubscriberSet::new(),
 289                layout_id_buffer: Default::default(),
 290                propagate_event: true,
 291                prompt_builder: Some(PromptBuilder::Default),
 292            }),
 293        });
 294
 295        init_app_menus(platform.as_ref(), &mut app.borrow_mut());
 296
 297        platform.on_quit(Box::new({
 298            let cx = app.clone();
 299            move || {
 300                cx.borrow_mut().shutdown();
 301            }
 302        }));
 303
 304        app
 305    }
 306
 307    /// Quit the application gracefully. Handlers registered with [`ModelContext::on_app_quit`]
 308    /// will be given 100ms to complete before exiting.
 309    pub fn shutdown(&mut self) {
 310        let mut futures = Vec::new();
 311
 312        for observer in self.quit_observers.remove(&()) {
 313            futures.push(observer(self));
 314        }
 315
 316        self.windows.clear();
 317        self.window_handles.clear();
 318        self.flush_effects();
 319
 320        let futures = futures::future::join_all(futures);
 321        if self
 322            .background_executor
 323            .block_with_timeout(SHUTDOWN_TIMEOUT, futures)
 324            .is_err()
 325        {
 326            log::error!("timed out waiting on app_will_quit");
 327        }
 328    }
 329
 330    /// Gracefully quit the application via the platform's standard routine.
 331    pub fn quit(&mut self) {
 332        self.platform.quit();
 333    }
 334
 335    /// Schedules all windows in the application to be redrawn. This can be called
 336    /// multiple times in an update cycle and still result in a single redraw.
 337    pub fn refresh(&mut self) {
 338        self.pending_effects.push_back(Effect::Refresh);
 339    }
 340
 341    pub(crate) fn update<R>(&mut self, update: impl FnOnce(&mut Self) -> R) -> R {
 342        self.pending_updates += 1;
 343        let result = update(self);
 344        if !self.flushing_effects && self.pending_updates == 1 {
 345            self.flushing_effects = true;
 346            self.flush_effects();
 347            self.flushing_effects = false;
 348        }
 349        self.pending_updates -= 1;
 350        result
 351    }
 352
 353    /// Arrange a callback to be invoked when the given model or view calls `notify` on its respective context.
 354    pub fn observe<W, E>(
 355        &mut self,
 356        entity: &E,
 357        mut on_notify: impl FnMut(E, &mut AppContext) + 'static,
 358    ) -> Subscription
 359    where
 360        W: 'static,
 361        E: Entity<W>,
 362    {
 363        self.observe_internal(entity, move |e, cx| {
 364            on_notify(e, cx);
 365            true
 366        })
 367    }
 368
 369    pub(crate) fn new_observer(&mut self, key: EntityId, value: Handler) -> Subscription {
 370        let (subscription, activate) = self.observers.insert(key, value);
 371        self.defer(move |_| activate());
 372        subscription
 373    }
 374    pub(crate) fn observe_internal<W, E>(
 375        &mut self,
 376        entity: &E,
 377        mut on_notify: impl FnMut(E, &mut AppContext) -> bool + 'static,
 378    ) -> Subscription
 379    where
 380        W: 'static,
 381        E: Entity<W>,
 382    {
 383        let entity_id = entity.entity_id();
 384        let handle = entity.downgrade();
 385        self.new_observer(
 386            entity_id,
 387            Box::new(move |cx| {
 388                if let Some(handle) = E::upgrade_from(&handle) {
 389                    on_notify(handle, cx)
 390                } else {
 391                    false
 392                }
 393            }),
 394        )
 395    }
 396
 397    /// Arrange for the given callback to be invoked whenever the given model or view emits an event of a given type.
 398    /// The callback is provided a handle to the emitting entity and a reference to the emitted event.
 399    pub fn subscribe<T, E, Event>(
 400        &mut self,
 401        entity: &E,
 402        mut on_event: impl FnMut(E, &Event, &mut AppContext) + 'static,
 403    ) -> Subscription
 404    where
 405        T: 'static + EventEmitter<Event>,
 406        E: Entity<T>,
 407        Event: 'static,
 408    {
 409        self.subscribe_internal(entity, move |entity, event, cx| {
 410            on_event(entity, event, cx);
 411            true
 412        })
 413    }
 414
 415    pub(crate) fn new_subscription(
 416        &mut self,
 417        key: EntityId,
 418        value: (TypeId, Listener),
 419    ) -> Subscription {
 420        let (subscription, activate) = self.event_listeners.insert(key, value);
 421        self.defer(move |_| activate());
 422        subscription
 423    }
 424    pub(crate) fn subscribe_internal<T, E, Evt>(
 425        &mut self,
 426        entity: &E,
 427        mut on_event: impl FnMut(E, &Evt, &mut AppContext) -> bool + 'static,
 428    ) -> Subscription
 429    where
 430        T: 'static + EventEmitter<Evt>,
 431        E: Entity<T>,
 432        Evt: 'static,
 433    {
 434        let entity_id = entity.entity_id();
 435        let entity = entity.downgrade();
 436        self.new_subscription(
 437            entity_id,
 438            (
 439                TypeId::of::<Evt>(),
 440                Box::new(move |event, cx| {
 441                    let event: &Evt = event.downcast_ref().expect("invalid event type");
 442                    if let Some(handle) = E::upgrade_from(&entity) {
 443                        on_event(handle, event, cx)
 444                    } else {
 445                        false
 446                    }
 447                }),
 448            ),
 449        )
 450    }
 451
 452    /// Returns handles to all open windows in the application.
 453    /// Each handle could be downcast to a handle typed for the root view of that window.
 454    /// To find all windows of a given type, you could filter on
 455    pub fn windows(&self) -> Vec<AnyWindowHandle> {
 456        self.windows
 457            .keys()
 458            .flat_map(|window_id| self.window_handles.get(&window_id).copied())
 459            .collect()
 460    }
 461
 462    /// Returns a handle to the window that is currently focused at the platform level, if one exists.
 463    pub fn active_window(&self) -> Option<AnyWindowHandle> {
 464        self.platform.active_window()
 465    }
 466
 467    /// Opens a new window with the given option and the root view returned by the given function.
 468    /// The function is invoked with a `WindowContext`, which can be used to interact with window-specific
 469    /// functionality.
 470    pub fn open_window<V: 'static + Render>(
 471        &mut self,
 472        options: crate::WindowOptions,
 473        build_root_view: impl FnOnce(&mut WindowContext) -> View<V>,
 474    ) -> anyhow::Result<WindowHandle<V>> {
 475        self.update(|cx| {
 476            let id = cx.windows.insert(None);
 477            let handle = WindowHandle::new(id);
 478            match Window::new(handle.into(), options, cx) {
 479                Ok(mut window) => {
 480                    let root_view = build_root_view(&mut WindowContext::new(cx, &mut window));
 481                    window.root_view.replace(root_view.into());
 482                    WindowContext::new(cx, &mut window).defer(|cx| cx.appearance_changed());
 483                    cx.window_handles.insert(id, window.handle);
 484                    cx.windows.get_mut(id).unwrap().replace(window);
 485                    Ok(handle)
 486                }
 487                Err(e) => {
 488                    cx.windows.remove(id);
 489                    return Err(e);
 490                }
 491            }
 492        })
 493    }
 494
 495    /// Instructs the platform to activate the application by bringing it to the foreground.
 496    pub fn activate(&self, ignoring_other_apps: bool) {
 497        self.platform.activate(ignoring_other_apps);
 498    }
 499
 500    /// Hide the application at the platform level.
 501    pub fn hide(&self) {
 502        self.platform.hide();
 503    }
 504
 505    /// Hide other applications at the platform level.
 506    pub fn hide_other_apps(&self) {
 507        self.platform.hide_other_apps();
 508    }
 509
 510    /// Unhide other applications at the platform level.
 511    pub fn unhide_other_apps(&self) {
 512        self.platform.unhide_other_apps();
 513    }
 514
 515    /// Returns the list of currently active displays.
 516    pub fn displays(&self) -> Vec<Rc<dyn PlatformDisplay>> {
 517        self.platform.displays()
 518    }
 519
 520    /// Returns the primary display that will be used for new windows.
 521    pub fn primary_display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 522        self.platform.primary_display()
 523    }
 524
 525    /// Returns the display with the given ID, if one exists.
 526    pub fn find_display(&self, id: DisplayId) -> Option<Rc<dyn PlatformDisplay>> {
 527        self.displays()
 528            .iter()
 529            .find(|display| display.id() == id)
 530            .cloned()
 531    }
 532
 533    /// Returns the appearance of the application's windows.
 534    pub fn window_appearance(&self) -> WindowAppearance {
 535        self.platform.window_appearance()
 536    }
 537
 538    /// Writes data to the primary selection buffer.
 539    /// Only available on Linux.
 540    #[cfg(target_os = "linux")]
 541    pub fn write_to_primary(&self, item: ClipboardItem) {
 542        self.platform.write_to_primary(item)
 543    }
 544
 545    /// Writes data to the platform clipboard.
 546    pub fn write_to_clipboard(&self, item: ClipboardItem) {
 547        self.platform.write_to_clipboard(item)
 548    }
 549
 550    /// Reads data from the primary selection buffer.
 551    /// Only available on Linux.
 552    #[cfg(target_os = "linux")]
 553    pub fn read_from_primary(&self) -> Option<ClipboardItem> {
 554        self.platform.read_from_primary()
 555    }
 556
 557    /// Reads data from the platform clipboard.
 558    pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
 559        self.platform.read_from_clipboard()
 560    }
 561
 562    /// Writes credentials to the platform keychain.
 563    pub fn write_credentials(
 564        &self,
 565        url: &str,
 566        username: &str,
 567        password: &[u8],
 568    ) -> Task<Result<()>> {
 569        self.platform.write_credentials(url, username, password)
 570    }
 571
 572    /// Reads credentials from the platform keychain.
 573    pub fn read_credentials(&self, url: &str) -> Task<Result<Option<(String, Vec<u8>)>>> {
 574        self.platform.read_credentials(url)
 575    }
 576
 577    /// Deletes credentials from the platform keychain.
 578    pub fn delete_credentials(&self, url: &str) -> Task<Result<()>> {
 579        self.platform.delete_credentials(url)
 580    }
 581
 582    /// Directs the platform's default browser to open the given URL.
 583    pub fn open_url(&self, url: &str) {
 584        self.platform.open_url(url);
 585    }
 586
 587    /// register_url_scheme requests that the given scheme (e.g. `zed` for `zed://` urls)
 588    /// is opened by the current app.
 589    /// On some platforms (e.g. macOS) you may be able to register URL schemes as part of app
 590    /// distribution, but this method exists to let you register schemes at runtime.
 591    pub fn register_url_scheme(&self, scheme: &str) -> Task<Result<()>> {
 592        self.platform.register_url_scheme(scheme)
 593    }
 594
 595    /// Returns the full pathname of the current app bundle.
 596    /// If the app is not being run from a bundle, returns an error.
 597    pub fn app_path(&self) -> Result<PathBuf> {
 598        self.platform.app_path()
 599    }
 600
 601    /// On Linux, returns the name of the compositor in use.
 602    /// Is blank on other platforms.
 603    pub fn compositor_name(&self) -> &'static str {
 604        self.platform.compositor_name()
 605    }
 606
 607    /// Returns the file URL of the executable with the specified name in the application bundle
 608    pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
 609        self.platform.path_for_auxiliary_executable(name)
 610    }
 611
 612    /// Displays a platform modal for selecting paths.
 613    /// When one or more paths are selected, they'll be relayed asynchronously via the returned oneshot channel.
 614    /// If cancelled, a `None` will be relayed instead.
 615    pub fn prompt_for_paths(
 616        &self,
 617        options: PathPromptOptions,
 618    ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
 619        self.platform.prompt_for_paths(options)
 620    }
 621
 622    /// Displays a platform modal for selecting a new path where a file can be saved.
 623    /// The provided directory will be used to set the initial location.
 624    /// When a path is selected, it is relayed asynchronously via the returned oneshot channel.
 625    /// If cancelled, a `None` will be relayed instead.
 626    pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
 627        self.platform.prompt_for_new_path(directory)
 628    }
 629
 630    /// Reveals the specified path at the platform level, such as in Finder on macOS.
 631    pub fn reveal_path(&self, path: &Path) {
 632        self.platform.reveal_path(path)
 633    }
 634
 635    /// Returns whether the user has configured scrollbars to auto-hide at the platform level.
 636    pub fn should_auto_hide_scrollbars(&self) -> bool {
 637        self.platform.should_auto_hide_scrollbars()
 638    }
 639
 640    /// Restart the application.
 641    pub fn restart(&self, binary_path: Option<PathBuf>) {
 642        self.platform.restart(binary_path)
 643    }
 644
 645    /// Returns the local timezone at the platform level.
 646    pub fn local_timezone(&self) -> UtcOffset {
 647        self.platform.local_timezone()
 648    }
 649
 650    /// Updates the http client assigned to GPUI
 651    pub fn update_http_client(&mut self, new_client: Arc<dyn HttpClient>) {
 652        self.http_client = new_client;
 653    }
 654
 655    /// Returns the http client assigned to GPUI
 656    pub fn http_client(&self) -> Arc<dyn HttpClient> {
 657        self.http_client.clone()
 658    }
 659
 660    /// Returns the SVG renderer GPUI uses
 661    pub(crate) fn svg_renderer(&self) -> SvgRenderer {
 662        self.svg_renderer.clone()
 663    }
 664
 665    pub(crate) fn push_effect(&mut self, effect: Effect) {
 666        match &effect {
 667            Effect::Notify { emitter } => {
 668                if !self.pending_notifications.insert(*emitter) {
 669                    return;
 670                }
 671            }
 672            Effect::NotifyGlobalObservers { global_type } => {
 673                if !self.pending_global_notifications.insert(*global_type) {
 674                    return;
 675                }
 676            }
 677            _ => {}
 678        };
 679
 680        self.pending_effects.push_back(effect);
 681    }
 682
 683    /// Called at the end of [`AppContext::update`] to complete any side effects
 684    /// such as notifying observers, emitting events, etc. Effects can themselves
 685    /// cause effects, so we continue looping until all effects are processed.
 686    fn flush_effects(&mut self) {
 687        loop {
 688            self.release_dropped_entities();
 689            self.release_dropped_focus_handles();
 690
 691            if let Some(effect) = self.pending_effects.pop_front() {
 692                match effect {
 693                    Effect::Notify { emitter } => {
 694                        self.apply_notify_effect(emitter);
 695                    }
 696
 697                    Effect::Emit {
 698                        emitter,
 699                        event_type,
 700                        event,
 701                    } => self.apply_emit_effect(emitter, event_type, event),
 702
 703                    Effect::Refresh => {
 704                        self.apply_refresh_effect();
 705                    }
 706
 707                    Effect::NotifyGlobalObservers { global_type } => {
 708                        self.apply_notify_global_observers_effect(global_type);
 709                    }
 710
 711                    Effect::Defer { callback } => {
 712                        self.apply_defer_effect(callback);
 713                    }
 714                }
 715            } else {
 716                #[cfg(any(test, feature = "test-support"))]
 717                for window in self
 718                    .windows
 719                    .values()
 720                    .filter_map(|window| {
 721                        let window = window.as_ref()?;
 722                        window.dirty.get().then_some(window.handle)
 723                    })
 724                    .collect::<Vec<_>>()
 725                {
 726                    self.update_window(window, |_, cx| cx.draw()).unwrap();
 727                }
 728
 729                if self.pending_effects.is_empty() {
 730                    break;
 731                }
 732            }
 733        }
 734    }
 735
 736    /// Repeatedly called during `flush_effects` to release any entities whose
 737    /// reference count has become zero. We invoke any release observers before dropping
 738    /// each entity.
 739    fn release_dropped_entities(&mut self) {
 740        loop {
 741            let dropped = self.entities.take_dropped();
 742            if dropped.is_empty() {
 743                break;
 744            }
 745
 746            for (entity_id, mut entity) in dropped {
 747                self.observers.remove(&entity_id);
 748                self.event_listeners.remove(&entity_id);
 749                for release_callback in self.release_listeners.remove(&entity_id) {
 750                    release_callback(entity.as_mut(), self);
 751                }
 752            }
 753        }
 754    }
 755
 756    /// Repeatedly called during `flush_effects` to handle a focused handle being dropped.
 757    fn release_dropped_focus_handles(&mut self) {
 758        for window_handle in self.windows() {
 759            window_handle
 760                .update(self, |_, cx| {
 761                    let mut blur_window = false;
 762                    let focus = cx.window.focus;
 763                    cx.window.focus_handles.write().retain(|handle_id, count| {
 764                        if count.load(SeqCst) == 0 {
 765                            if focus == Some(handle_id) {
 766                                blur_window = true;
 767                            }
 768                            false
 769                        } else {
 770                            true
 771                        }
 772                    });
 773
 774                    if blur_window {
 775                        cx.blur();
 776                    }
 777                })
 778                .unwrap();
 779        }
 780    }
 781
 782    fn apply_notify_effect(&mut self, emitter: EntityId) {
 783        self.pending_notifications.remove(&emitter);
 784
 785        self.observers
 786            .clone()
 787            .retain(&emitter, |handler| handler(self));
 788    }
 789
 790    fn apply_emit_effect(&mut self, emitter: EntityId, event_type: TypeId, event: Box<dyn Any>) {
 791        self.event_listeners
 792            .clone()
 793            .retain(&emitter, |(stored_type, handler)| {
 794                if *stored_type == event_type {
 795                    handler(event.as_ref(), self)
 796                } else {
 797                    true
 798                }
 799            });
 800    }
 801
 802    fn apply_refresh_effect(&mut self) {
 803        for window in self.windows.values_mut() {
 804            if let Some(window) = window.as_mut() {
 805                window.dirty.set(true);
 806            }
 807        }
 808    }
 809
 810    fn apply_notify_global_observers_effect(&mut self, type_id: TypeId) {
 811        self.pending_global_notifications.remove(&type_id);
 812        self.global_observers
 813            .clone()
 814            .retain(&type_id, |observer| observer(self));
 815    }
 816
 817    fn apply_defer_effect(&mut self, callback: Box<dyn FnOnce(&mut Self) + 'static>) {
 818        callback(self);
 819    }
 820
 821    /// Creates an `AsyncAppContext`, which can be cloned and has a static lifetime
 822    /// so it can be held across `await` points.
 823    pub fn to_async(&self) -> AsyncAppContext {
 824        AsyncAppContext {
 825            app: self.this.clone(),
 826            background_executor: self.background_executor.clone(),
 827            foreground_executor: self.foreground_executor.clone(),
 828        }
 829    }
 830
 831    /// Obtains a reference to the executor, which can be used to spawn futures.
 832    pub fn background_executor(&self) -> &BackgroundExecutor {
 833        &self.background_executor
 834    }
 835
 836    /// Obtains a reference to the executor, which can be used to spawn futures.
 837    pub fn foreground_executor(&self) -> &ForegroundExecutor {
 838        &self.foreground_executor
 839    }
 840
 841    /// Spawns the future returned by the given function on the thread pool. The closure will be invoked
 842    /// with [AsyncAppContext], which allows the application state to be accessed across await points.
 843    pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut) -> Task<R>
 844    where
 845        Fut: Future<Output = R> + 'static,
 846        R: 'static,
 847    {
 848        self.foreground_executor.spawn(f(self.to_async()))
 849    }
 850
 851    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 852    /// that are currently on the stack to be returned to the app.
 853    pub fn defer(&mut self, f: impl FnOnce(&mut AppContext) + 'static) {
 854        self.push_effect(Effect::Defer {
 855            callback: Box::new(f),
 856        });
 857    }
 858
 859    /// Accessor for the application's asset source, which is provided when constructing the `App`.
 860    pub fn asset_source(&self) -> &Arc<dyn AssetSource> {
 861        &self.asset_source
 862    }
 863
 864    /// Accessor for the text system.
 865    pub fn text_system(&self) -> &Arc<TextSystem> {
 866        &self.text_system
 867    }
 868
 869    /// Check whether a global of the given type has been assigned.
 870    pub fn has_global<G: Global>(&self) -> bool {
 871        self.globals_by_type.contains_key(&TypeId::of::<G>())
 872    }
 873
 874    /// Access the global of the given type. Panics if a global for that type has not been assigned.
 875    #[track_caller]
 876    pub fn global<G: Global>(&self) -> &G {
 877        self.globals_by_type
 878            .get(&TypeId::of::<G>())
 879            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
 880            .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
 881            .unwrap()
 882    }
 883
 884    /// Access the global of the given type if a value has been assigned.
 885    pub fn try_global<G: Global>(&self) -> Option<&G> {
 886        self.globals_by_type
 887            .get(&TypeId::of::<G>())
 888            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
 889    }
 890
 891    /// Access the global of the given type mutably. Panics if a global for that type has not been assigned.
 892    #[track_caller]
 893    pub fn global_mut<G: Global>(&mut self) -> &mut G {
 894        let global_type = TypeId::of::<G>();
 895        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 896        self.globals_by_type
 897            .get_mut(&global_type)
 898            .and_then(|any_state| any_state.downcast_mut::<G>())
 899            .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
 900            .unwrap()
 901    }
 902
 903    /// Access the global of the given type mutably. A default value is assigned if a global of this type has not
 904    /// yet been assigned.
 905    pub fn default_global<G: Global + Default>(&mut self) -> &mut G {
 906        let global_type = TypeId::of::<G>();
 907        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 908        self.globals_by_type
 909            .entry(global_type)
 910            .or_insert_with(|| Box::<G>::default())
 911            .downcast_mut::<G>()
 912            .unwrap()
 913    }
 914
 915    /// Sets the value of the global of the given type.
 916    pub fn set_global<G: Global>(&mut self, global: G) {
 917        let global_type = TypeId::of::<G>();
 918        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 919        self.globals_by_type.insert(global_type, Box::new(global));
 920    }
 921
 922    /// Clear all stored globals. Does not notify global observers.
 923    #[cfg(any(test, feature = "test-support"))]
 924    pub fn clear_globals(&mut self) {
 925        self.globals_by_type.drain();
 926    }
 927
 928    /// Remove the global of the given type from the app context. Does not notify global observers.
 929    pub fn remove_global<G: Global>(&mut self) -> G {
 930        let global_type = TypeId::of::<G>();
 931        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 932        *self
 933            .globals_by_type
 934            .remove(&global_type)
 935            .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<G>()))
 936            .downcast()
 937            .unwrap()
 938    }
 939
 940    /// Register a callback to be invoked when a global of the given type is updated.
 941    pub fn observe_global<G: Global>(
 942        &mut self,
 943        mut f: impl FnMut(&mut Self) + 'static,
 944    ) -> Subscription {
 945        let (subscription, activate) = self.global_observers.insert(
 946            TypeId::of::<G>(),
 947            Box::new(move |cx| {
 948                f(cx);
 949                true
 950            }),
 951        );
 952        self.defer(move |_| activate());
 953        subscription
 954    }
 955
 956    /// Move the global of the given type to the stack.
 957    pub(crate) fn lease_global<G: Global>(&mut self) -> GlobalLease<G> {
 958        GlobalLease::new(
 959            self.globals_by_type
 960                .remove(&TypeId::of::<G>())
 961                .ok_or_else(|| anyhow!("no global registered of type {}", type_name::<G>()))
 962                .unwrap(),
 963        )
 964    }
 965
 966    /// Restore the global of the given type after it is moved to the stack.
 967    pub(crate) fn end_global_lease<G: Global>(&mut self, lease: GlobalLease<G>) {
 968        let global_type = TypeId::of::<G>();
 969        self.push_effect(Effect::NotifyGlobalObservers { global_type });
 970        self.globals_by_type.insert(global_type, lease.global);
 971    }
 972
 973    pub(crate) fn new_view_observer(
 974        &mut self,
 975        key: TypeId,
 976        value: NewViewListener,
 977    ) -> Subscription {
 978        let (subscription, activate) = self.new_view_observers.insert(key, value);
 979        activate();
 980        subscription
 981    }
 982    /// Arrange for the given function to be invoked whenever a view of the specified type is created.
 983    /// The function will be passed a mutable reference to the view along with an appropriate context.
 984    pub fn observe_new_views<V: 'static>(
 985        &mut self,
 986        on_new: impl 'static + Fn(&mut V, &mut ViewContext<V>),
 987    ) -> Subscription {
 988        self.new_view_observer(
 989            TypeId::of::<V>(),
 990            Box::new(move |any_view: AnyView, cx: &mut WindowContext| {
 991                any_view
 992                    .downcast::<V>()
 993                    .unwrap()
 994                    .update(cx, |view_state, cx| {
 995                        on_new(view_state, cx);
 996                    })
 997            }),
 998        )
 999    }
1000
1001    /// Observe the release of a model or view. The callback is invoked after the model or view
1002    /// has no more strong references but before it has been dropped.
1003    pub fn observe_release<E, T>(
1004        &mut self,
1005        handle: &E,
1006        on_release: impl FnOnce(&mut T, &mut AppContext) + 'static,
1007    ) -> Subscription
1008    where
1009        E: Entity<T>,
1010        T: 'static,
1011    {
1012        let (subscription, activate) = self.release_listeners.insert(
1013            handle.entity_id(),
1014            Box::new(move |entity, cx| {
1015                let entity = entity.downcast_mut().expect("invalid entity type");
1016                on_release(entity, cx)
1017            }),
1018        );
1019        activate();
1020        subscription
1021    }
1022
1023    /// Register a callback to be invoked when a keystroke is received by the application
1024    /// in any window. Note that this fires after all other action and event mechanisms have resolved
1025    /// and that this API will not be invoked if the event's propagation is stopped.
1026    pub fn observe_keystrokes(
1027        &mut self,
1028        f: impl FnMut(&KeystrokeEvent, &mut WindowContext) + 'static,
1029    ) -> Subscription {
1030        fn inner(
1031            keystroke_observers: &mut SubscriberSet<(), KeystrokeObserver>,
1032            handler: KeystrokeObserver,
1033        ) -> Subscription {
1034            let (subscription, activate) = keystroke_observers.insert((), handler);
1035            activate();
1036            subscription
1037        }
1038        inner(&mut self.keystroke_observers, Box::new(f))
1039    }
1040
1041    /// Register key bindings.
1042    pub fn bind_keys(&mut self, bindings: impl IntoIterator<Item = KeyBinding>) {
1043        self.keymap.borrow_mut().add_bindings(bindings);
1044        self.pending_effects.push_back(Effect::Refresh);
1045    }
1046
1047    /// Clear all key bindings in the app.
1048    pub fn clear_key_bindings(&mut self) {
1049        self.keymap.borrow_mut().clear();
1050        self.pending_effects.push_back(Effect::Refresh);
1051    }
1052
1053    /// Register a global listener for actions invoked via the keyboard.
1054    pub fn on_action<A: Action>(&mut self, listener: impl Fn(&A, &mut Self) + 'static) {
1055        self.global_action_listeners
1056            .entry(TypeId::of::<A>())
1057            .or_default()
1058            .push(Rc::new(move |action, phase, cx| {
1059                if phase == DispatchPhase::Bubble {
1060                    let action = action.downcast_ref().unwrap();
1061                    listener(action, cx)
1062                }
1063            }));
1064    }
1065
1066    /// Event handlers propagate events by default. Call this method to stop dispatching to
1067    /// event handlers with a lower z-index (mouse) or higher in the tree (keyboard). This is
1068    /// the opposite of [`Self::propagate`]. It's also possible to cancel a call to [`Self::propagate`] by
1069    /// calling this method before effects are flushed.
1070    pub fn stop_propagation(&mut self) {
1071        self.propagate_event = false;
1072    }
1073
1074    /// Action handlers stop propagation by default during the bubble phase of action dispatch
1075    /// dispatching to action handlers higher in the element tree. This is the opposite of
1076    /// [`Self::stop_propagation`]. It's also possible to cancel a call to [`Self::stop_propagation`] by calling
1077    /// this method before effects are flushed.
1078    pub fn propagate(&mut self) {
1079        self.propagate_event = true;
1080    }
1081
1082    /// Build an action from some arbitrary data, typically a keymap entry.
1083    pub fn build_action(
1084        &self,
1085        name: &str,
1086        data: Option<serde_json::Value>,
1087    ) -> Result<Box<dyn Action>> {
1088        self.actions.build_action(name, data)
1089    }
1090
1091    /// Get a list of all action names that have been registered.
1092    /// in the application. Note that registration only allows for
1093    /// actions to be built dynamically, and is unrelated to binding
1094    /// actions in the element tree.
1095    pub fn all_action_names(&self) -> &[SharedString] {
1096        self.actions.all_action_names()
1097    }
1098
1099    /// Register a callback to be invoked when the application is about to quit.
1100    /// It is not possible to cancel the quit event at this point.
1101    pub fn on_app_quit<Fut>(
1102        &mut self,
1103        mut on_quit: impl FnMut(&mut AppContext) -> Fut + 'static,
1104    ) -> Subscription
1105    where
1106        Fut: 'static + Future<Output = ()>,
1107    {
1108        let (subscription, activate) = self.quit_observers.insert(
1109            (),
1110            Box::new(move |cx| {
1111                let future = on_quit(cx);
1112                future.boxed_local()
1113            }),
1114        );
1115        activate();
1116        subscription
1117    }
1118
1119    pub(crate) fn clear_pending_keystrokes(&mut self) {
1120        for window in self.windows() {
1121            window
1122                .update(self, |_, cx| {
1123                    cx.window
1124                        .rendered_frame
1125                        .dispatch_tree
1126                        .clear_pending_keystrokes();
1127                    cx.window
1128                        .next_frame
1129                        .dispatch_tree
1130                        .clear_pending_keystrokes();
1131                })
1132                .ok();
1133        }
1134    }
1135
1136    /// Checks if the given action is bound in the current context, as defined by the app's current focus,
1137    /// the bindings in the element tree, and any global action listeners.
1138    pub fn is_action_available(&mut self, action: &dyn Action) -> bool {
1139        let mut action_available = false;
1140        if let Some(window) = self.active_window() {
1141            if let Ok(window_action_available) =
1142                window.update(self, |_, cx| cx.is_action_available(action))
1143            {
1144                action_available = window_action_available;
1145            }
1146        }
1147
1148        action_available
1149            || self
1150                .global_action_listeners
1151                .contains_key(&action.as_any().type_id())
1152    }
1153
1154    /// Sets the menu bar for this application. This will replace any existing menu bar.
1155    pub fn set_menus(&mut self, menus: Vec<Menu>) {
1156        self.platform.set_menus(menus, &self.keymap.borrow());
1157    }
1158
1159    /// Gets the menu bar for this application.
1160    pub fn get_menus(&self) -> Option<Vec<OwnedMenu>> {
1161        self.platform.get_menus()
1162    }
1163
1164    /// Sets the right click menu for the app icon in the dock
1165    pub fn set_dock_menu(&mut self, menus: Vec<MenuItem>) {
1166        self.platform.set_dock_menu(menus, &self.keymap.borrow());
1167    }
1168
1169    /// Adds given path to the bottom of the list of recent paths for the application.
1170    /// The list is usually shown on the application icon's context menu in the dock,
1171    /// and allows to open the recent files via that context menu.
1172    /// If the path is already in the list, it will be moved to the bottom of the list.
1173    pub fn add_recent_document(&mut self, path: &Path) {
1174        self.platform.add_recent_document(path);
1175    }
1176
1177    /// Dispatch an action to the currently active window or global action handler
1178    /// See [action::Action] for more information on how actions work
1179    pub fn dispatch_action(&mut self, action: &dyn Action) {
1180        if let Some(active_window) = self.active_window() {
1181            active_window
1182                .update(self, |_, cx| cx.dispatch_action(action.boxed_clone()))
1183                .log_err();
1184        } else {
1185            self.dispatch_global_action(action);
1186        }
1187    }
1188
1189    fn dispatch_global_action(&mut self, action: &dyn Action) {
1190        self.propagate_event = true;
1191
1192        if let Some(mut global_listeners) = self
1193            .global_action_listeners
1194            .remove(&action.as_any().type_id())
1195        {
1196            for listener in &global_listeners {
1197                listener(action.as_any(), DispatchPhase::Capture, self);
1198                if !self.propagate_event {
1199                    break;
1200                }
1201            }
1202
1203            global_listeners.extend(
1204                self.global_action_listeners
1205                    .remove(&action.as_any().type_id())
1206                    .unwrap_or_default(),
1207            );
1208
1209            self.global_action_listeners
1210                .insert(action.as_any().type_id(), global_listeners);
1211        }
1212
1213        if self.propagate_event {
1214            if let Some(mut global_listeners) = self
1215                .global_action_listeners
1216                .remove(&action.as_any().type_id())
1217            {
1218                for listener in global_listeners.iter().rev() {
1219                    listener(action.as_any(), DispatchPhase::Bubble, self);
1220                    if !self.propagate_event {
1221                        break;
1222                    }
1223                }
1224
1225                global_listeners.extend(
1226                    self.global_action_listeners
1227                        .remove(&action.as_any().type_id())
1228                        .unwrap_or_default(),
1229                );
1230
1231                self.global_action_listeners
1232                    .insert(action.as_any().type_id(), global_listeners);
1233            }
1234        }
1235    }
1236
1237    /// Is there currently something being dragged?
1238    pub fn has_active_drag(&self) -> bool {
1239        self.active_drag.is_some()
1240    }
1241
1242    /// Set the prompt renderer for GPUI. This will replace the default or platform specific
1243    /// prompts with this custom implementation.
1244    pub fn set_prompt_builder(
1245        &mut self,
1246        renderer: impl Fn(
1247                PromptLevel,
1248                &str,
1249                Option<&str>,
1250                &[&str],
1251                PromptHandle,
1252                &mut WindowContext,
1253            ) -> RenderablePromptHandle
1254            + 'static,
1255    ) {
1256        self.prompt_builder = Some(PromptBuilder::Custom(Box::new(renderer)))
1257    }
1258}
1259
1260impl Context for AppContext {
1261    type Result<T> = T;
1262
1263    /// Build an entity that is owned by the application. The given function will be invoked with
1264    /// a `ModelContext` and must return an object representing the entity. A `Model` handle will be returned,
1265    /// which can be used to access the entity in a context.
1266    fn new_model<T: 'static>(
1267        &mut self,
1268        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
1269    ) -> Model<T> {
1270        self.update(|cx| {
1271            let slot = cx.entities.reserve();
1272            let entity = build_model(&mut ModelContext::new(cx, slot.downgrade()));
1273            cx.entities.insert(slot, entity)
1274        })
1275    }
1276
1277    fn reserve_model<T: 'static>(&mut self) -> Self::Result<Reservation<T>> {
1278        Reservation(self.entities.reserve())
1279    }
1280
1281    fn insert_model<T: 'static>(
1282        &mut self,
1283        reservation: Reservation<T>,
1284        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
1285    ) -> Self::Result<Model<T>> {
1286        self.update(|cx| {
1287            let slot = reservation.0;
1288            let entity = build_model(&mut ModelContext::new(cx, slot.downgrade()));
1289            cx.entities.insert(slot, entity)
1290        })
1291    }
1292
1293    /// Updates the entity referenced by the given model. The function is passed a mutable reference to the
1294    /// entity along with a `ModelContext` for the entity.
1295    fn update_model<T: 'static, R>(
1296        &mut self,
1297        model: &Model<T>,
1298        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1299    ) -> R {
1300        self.update(|cx| {
1301            let mut entity = cx.entities.lease(model);
1302            let result = update(&mut entity, &mut ModelContext::new(cx, model.downgrade()));
1303            cx.entities.end_lease(entity);
1304            result
1305        })
1306    }
1307
1308    fn read_model<T, R>(
1309        &self,
1310        handle: &Model<T>,
1311        read: impl FnOnce(&T, &AppContext) -> R,
1312    ) -> Self::Result<R>
1313    where
1314        T: 'static,
1315    {
1316        let entity = self.entities.read(handle);
1317        read(entity, self)
1318    }
1319
1320    fn update_window<T, F>(&mut self, handle: AnyWindowHandle, update: F) -> Result<T>
1321    where
1322        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1323    {
1324        self.update(|cx| {
1325            let mut window = cx
1326                .windows
1327                .get_mut(handle.id)
1328                .ok_or_else(|| anyhow!("window not found"))?
1329                .take()
1330                .ok_or_else(|| anyhow!("window not found"))?;
1331
1332            let root_view = window.root_view.clone().unwrap();
1333            let result = update(root_view, &mut WindowContext::new(cx, &mut window));
1334
1335            if window.removed {
1336                cx.window_handles.remove(&handle.id);
1337                cx.windows.remove(handle.id);
1338            } else {
1339                cx.windows
1340                    .get_mut(handle.id)
1341                    .ok_or_else(|| anyhow!("window not found"))?
1342                    .replace(window);
1343            }
1344
1345            Ok(result)
1346        })
1347    }
1348
1349    fn read_window<T, R>(
1350        &self,
1351        window: &WindowHandle<T>,
1352        read: impl FnOnce(View<T>, &AppContext) -> R,
1353    ) -> Result<R>
1354    where
1355        T: 'static,
1356    {
1357        let window = self
1358            .windows
1359            .get(window.id)
1360            .ok_or_else(|| anyhow!("window not found"))?
1361            .as_ref()
1362            .unwrap();
1363
1364        let root_view = window.root_view.clone().unwrap();
1365        let view = root_view
1366            .downcast::<T>()
1367            .map_err(|_| anyhow!("root view's type has changed"))?;
1368
1369        Ok(read(view, self))
1370    }
1371}
1372
1373/// These effects are processed at the end of each application update cycle.
1374pub(crate) enum Effect {
1375    Notify {
1376        emitter: EntityId,
1377    },
1378    Emit {
1379        emitter: EntityId,
1380        event_type: TypeId,
1381        event: Box<dyn Any>,
1382    },
1383    Refresh,
1384    NotifyGlobalObservers {
1385        global_type: TypeId,
1386    },
1387    Defer {
1388        callback: Box<dyn FnOnce(&mut AppContext) + 'static>,
1389    },
1390}
1391
1392/// Wraps a global variable value during `update_global` while the value has been moved to the stack.
1393pub(crate) struct GlobalLease<G: Global> {
1394    global: Box<dyn Any>,
1395    global_type: PhantomData<G>,
1396}
1397
1398impl<G: Global> GlobalLease<G> {
1399    fn new(global: Box<dyn Any>) -> Self {
1400        GlobalLease {
1401            global,
1402            global_type: PhantomData,
1403        }
1404    }
1405}
1406
1407impl<G: Global> Deref for GlobalLease<G> {
1408    type Target = G;
1409
1410    fn deref(&self) -> &Self::Target {
1411        self.global.downcast_ref().unwrap()
1412    }
1413}
1414
1415impl<G: Global> DerefMut for GlobalLease<G> {
1416    fn deref_mut(&mut self) -> &mut Self::Target {
1417        self.global.downcast_mut().unwrap()
1418    }
1419}
1420
1421/// Contains state associated with an active drag operation, started by dragging an element
1422/// within the window or by dragging into the app from the underlying platform.
1423pub struct AnyDrag {
1424    /// The view used to render this drag
1425    pub view: AnyView,
1426
1427    /// The value of the dragged item, to be dropped
1428    pub value: Box<dyn Any>,
1429
1430    /// This is used to render the dragged item in the same place
1431    /// on the original element that the drag was initiated
1432    pub cursor_offset: Point<Pixels>,
1433}
1434
1435/// Contains state associated with a tooltip. You'll only need this struct if you're implementing
1436/// tooltip behavior on a custom element. Otherwise, use [Div::tooltip].
1437#[derive(Clone)]
1438pub struct AnyTooltip {
1439    /// The view used to display the tooltip
1440    pub view: AnyView,
1441
1442    /// The absolute position of the mouse when the tooltip was deployed.
1443    pub mouse_position: Point<Pixels>,
1444}
1445
1446/// A keystroke event, and potentially the associated action
1447#[derive(Debug)]
1448pub struct KeystrokeEvent {
1449    /// The keystroke that occurred
1450    pub keystroke: Keystroke,
1451
1452    /// The action that was resolved for the keystroke, if any
1453    pub action: Option<Box<dyn Action>>,
1454}