1mod async_context;
2mod entity_map;
3mod model_context;
4#[cfg(any(test, feature = "test-support"))]
5mod test_context;
6
7pub use async_context::*;
8use derive_more::{Deref, DerefMut};
9pub use entity_map::*;
10pub use model_context::*;
11use refineable::Refineable;
12use smallvec::SmallVec;
13#[cfg(any(test, feature = "test-support"))]
14pub use test_context::*;
15
16use crate::{
17 current_platform, image_cache::ImageCache, Action, AnyBox, AnyView, AnyWindowHandle,
18 AppMetadata, AssetSource, BackgroundExecutor, ClipboardItem, Context, DispatchPhase, DisplayId,
19 Entity, EventEmitter, FocusEvent, FocusHandle, FocusId, ForegroundExecutor, KeyBinding, Keymap,
20 LayoutId, PathPromptOptions, Pixels, Platform, PlatformDisplay, Point, Render, SubscriberSet,
21 Subscription, SvgRenderer, Task, TextStyle, TextStyleRefinement, TextSystem, View, ViewContext,
22 Window, WindowContext, WindowHandle, WindowId,
23};
24use anyhow::{anyhow, Result};
25use collections::{HashMap, HashSet, VecDeque};
26use futures::{channel::oneshot, future::LocalBoxFuture, Future};
27use parking_lot::Mutex;
28use slotmap::SlotMap;
29use std::{
30 any::{type_name, Any, TypeId},
31 cell::{Ref, RefCell, RefMut},
32 marker::PhantomData,
33 mem,
34 ops::{Deref, DerefMut},
35 path::{Path, PathBuf},
36 rc::{Rc, Weak},
37 sync::{atomic::Ordering::SeqCst, Arc},
38 time::Duration,
39};
40use util::http::{self, HttpClient};
41
42/// Temporary(?) wrapper around RefCell<AppContext> to help us debug any double borrows.
43/// Strongly consider removing after stabilization.
44pub struct AppCell {
45 app: RefCell<AppContext>,
46}
47
48impl AppCell {
49 #[track_caller]
50 pub fn borrow(&self) -> AppRef {
51 if let Some(_) = option_env!("TRACK_THREAD_BORROWS") {
52 let thread_id = std::thread::current().id();
53 eprintln!("borrowed {thread_id:?}");
54 }
55 AppRef(self.app.borrow())
56 }
57
58 #[track_caller]
59 pub fn borrow_mut(&self) -> AppRefMut {
60 if let Some(_) = option_env!("TRACK_THREAD_BORROWS") {
61 let thread_id = std::thread::current().id();
62 eprintln!("borrowed {thread_id:?}");
63 }
64 AppRefMut(self.app.borrow_mut())
65 }
66}
67
68#[derive(Deref, DerefMut)]
69pub struct AppRef<'a>(Ref<'a, AppContext>);
70
71impl<'a> Drop for AppRef<'a> {
72 fn drop(&mut self) {
73 if let Some(_) = option_env!("TRACK_THREAD_BORROWS") {
74 let thread_id = std::thread::current().id();
75 eprintln!("dropped borrow from {thread_id:?}");
76 }
77 }
78}
79
80#[derive(Deref, DerefMut)]
81pub struct AppRefMut<'a>(RefMut<'a, AppContext>);
82
83impl<'a> Drop for AppRefMut<'a> {
84 fn drop(&mut self) {
85 if let Some(_) = option_env!("TRACK_THREAD_BORROWS") {
86 let thread_id = std::thread::current().id();
87 eprintln!("dropped {thread_id:?}");
88 }
89 }
90}
91
92pub struct App(Rc<AppCell>);
93
94/// Represents an application before it is fully launched. Once your app is
95/// configured, you'll start the app with `App::run`.
96impl App {
97 /// Builds an app with the given asset source.
98 pub fn production(asset_source: Arc<dyn AssetSource>) -> Self {
99 Self(AppContext::new(
100 current_platform(),
101 asset_source,
102 http::client(),
103 ))
104 }
105
106 /// Start the application. The provided callback will be called once the
107 /// app is fully launched.
108 pub fn run<F>(self, on_finish_launching: F)
109 where
110 F: 'static + FnOnce(&mut AppContext),
111 {
112 let this = self.0.clone();
113 let platform = self.0.borrow().platform.clone();
114 platform.run(Box::new(move || {
115 let cx = &mut *this.borrow_mut();
116 on_finish_launching(cx);
117 }));
118 }
119
120 /// Register a handler to be invoked when the platform instructs the application
121 /// to open one or more URLs.
122 pub fn on_open_urls<F>(&self, mut callback: F) -> &Self
123 where
124 F: 'static + FnMut(Vec<String>, &mut AppContext),
125 {
126 let this = Rc::downgrade(&self.0);
127 self.0.borrow().platform.on_open_urls(Box::new(move |urls| {
128 if let Some(app) = this.upgrade() {
129 callback(urls, &mut *app.borrow_mut());
130 }
131 }));
132 self
133 }
134
135 pub fn on_reopen<F>(&self, mut callback: F) -> &Self
136 where
137 F: 'static + FnMut(&mut AppContext),
138 {
139 let this = Rc::downgrade(&self.0);
140 self.0.borrow_mut().platform.on_reopen(Box::new(move || {
141 if let Some(app) = this.upgrade() {
142 callback(&mut app.borrow_mut());
143 }
144 }));
145 self
146 }
147
148 pub fn metadata(&self) -> AppMetadata {
149 self.0.borrow().app_metadata.clone()
150 }
151
152 pub fn background_executor(&self) -> BackgroundExecutor {
153 self.0.borrow().background_executor.clone()
154 }
155
156 pub fn foreground_executor(&self) -> ForegroundExecutor {
157 self.0.borrow().foreground_executor.clone()
158 }
159
160 pub fn text_system(&self) -> Arc<TextSystem> {
161 self.0.borrow().text_system.clone()
162 }
163}
164
165pub(crate) type FrameCallback = Box<dyn FnOnce(&mut AppContext)>;
166type Handler = Box<dyn FnMut(&mut AppContext) -> bool + 'static>;
167type Listener = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool + 'static>;
168type QuitHandler = Box<dyn FnOnce(&mut AppContext) -> LocalBoxFuture<'static, ()> + 'static>;
169type ReleaseListener = Box<dyn FnOnce(&mut dyn Any, &mut AppContext) + 'static>;
170type NewViewListener = Box<dyn FnMut(AnyView, &mut WindowContext) + 'static>;
171
172// struct FrameConsumer {
173// next_frame_callbacks: Vec<FrameCallback>,
174// task: Task<()>,
175// display_linker
176// }
177
178pub struct AppContext {
179 pub(crate) this: Weak<AppCell>,
180 pub(crate) platform: Rc<dyn Platform>,
181 app_metadata: AppMetadata,
182 text_system: Arc<TextSystem>,
183 flushing_effects: bool,
184 pending_updates: usize,
185 pub(crate) active_drag: Option<AnyDrag>,
186 pub(crate) active_tooltip: Option<AnyTooltip>,
187 pub(crate) next_frame_callbacks: HashMap<DisplayId, Vec<FrameCallback>>,
188 pub(crate) frame_consumers: HashMap<DisplayId, Task<()>>,
189 pub(crate) background_executor: BackgroundExecutor,
190 pub(crate) foreground_executor: ForegroundExecutor,
191 pub(crate) svg_renderer: SvgRenderer,
192 asset_source: Arc<dyn AssetSource>,
193 pub(crate) image_cache: ImageCache,
194 pub(crate) text_style_stack: Vec<TextStyleRefinement>,
195 pub(crate) globals_by_type: HashMap<TypeId, AnyBox>,
196 pub(crate) entities: EntityMap,
197 pub(crate) new_view_observers: SubscriberSet<TypeId, NewViewListener>,
198 pub(crate) windows: SlotMap<WindowId, Option<Window>>,
199 pub(crate) keymap: Arc<Mutex<Keymap>>,
200 pub(crate) global_action_listeners:
201 HashMap<TypeId, Vec<Box<dyn Fn(&dyn Action, DispatchPhase, &mut Self)>>>,
202 pending_effects: VecDeque<Effect>,
203 pub(crate) pending_notifications: HashSet<EntityId>,
204 pub(crate) pending_global_notifications: HashSet<TypeId>,
205 pub(crate) observers: SubscriberSet<EntityId, Handler>,
206 // TypeId is the type of the event that the listener callback expects
207 pub(crate) event_listeners: SubscriberSet<EntityId, (TypeId, Listener)>,
208 pub(crate) release_listeners: SubscriberSet<EntityId, ReleaseListener>,
209 pub(crate) global_observers: SubscriberSet<TypeId, Handler>,
210 pub(crate) quit_observers: SubscriberSet<(), QuitHandler>,
211 pub(crate) layout_id_buffer: Vec<LayoutId>, // We recycle this memory across layout requests.
212 pub(crate) propagate_event: bool,
213}
214
215impl AppContext {
216 pub(crate) fn new(
217 platform: Rc<dyn Platform>,
218 asset_source: Arc<dyn AssetSource>,
219 http_client: Arc<dyn HttpClient>,
220 ) -> Rc<AppCell> {
221 let executor = platform.background_executor();
222 let foreground_executor = platform.foreground_executor();
223 assert!(
224 executor.is_main_thread(),
225 "must construct App on main thread"
226 );
227
228 let text_system = Arc::new(TextSystem::new(platform.text_system()));
229 let entities = EntityMap::new();
230
231 let app_metadata = AppMetadata {
232 os_name: platform.os_name(),
233 os_version: platform.os_version().ok(),
234 app_version: platform.app_version().ok(),
235 };
236
237 let app = Rc::new_cyclic(|this| AppCell {
238 app: RefCell::new(AppContext {
239 this: this.clone(),
240 platform: platform.clone(),
241 app_metadata,
242 text_system,
243 flushing_effects: false,
244 pending_updates: 0,
245 active_drag: None,
246 active_tooltip: None,
247 next_frame_callbacks: HashMap::default(),
248 frame_consumers: HashMap::default(),
249 background_executor: executor,
250 foreground_executor,
251 svg_renderer: SvgRenderer::new(asset_source.clone()),
252 asset_source,
253 image_cache: ImageCache::new(http_client),
254 text_style_stack: Vec::new(),
255 globals_by_type: HashMap::default(),
256 entities,
257 new_view_observers: SubscriberSet::new(),
258 windows: SlotMap::with_key(),
259 keymap: Arc::new(Mutex::new(Keymap::default())),
260 global_action_listeners: HashMap::default(),
261 pending_effects: VecDeque::new(),
262 pending_notifications: HashSet::default(),
263 pending_global_notifications: HashSet::default(),
264 observers: SubscriberSet::new(),
265 event_listeners: SubscriberSet::new(),
266 release_listeners: SubscriberSet::new(),
267 global_observers: SubscriberSet::new(),
268 quit_observers: SubscriberSet::new(),
269 layout_id_buffer: Default::default(),
270 propagate_event: true,
271 }),
272 });
273
274 platform.on_quit(Box::new({
275 let cx = app.clone();
276 move || {
277 cx.borrow_mut().shutdown();
278 }
279 }));
280
281 app
282 }
283
284 /// Quit the application gracefully. Handlers registered with `ModelContext::on_app_quit`
285 /// will be given 100ms to complete before exiting.
286 pub fn shutdown(&mut self) {
287 let mut futures = Vec::new();
288
289 for observer in self.quit_observers.remove(&()) {
290 futures.push(observer(self));
291 }
292
293 self.windows.clear();
294 self.flush_effects();
295
296 let futures = futures::future::join_all(futures);
297 if self
298 .background_executor
299 .block_with_timeout(Duration::from_millis(100), futures)
300 .is_err()
301 {
302 log::error!("timed out waiting on app_will_quit");
303 }
304 }
305
306 pub fn quit(&mut self) {
307 self.platform.quit();
308 }
309
310 pub fn app_metadata(&self) -> AppMetadata {
311 self.app_metadata.clone()
312 }
313
314 /// Schedules all windows in the application to be redrawn. This can be called
315 /// multiple times in an update cycle and still result in a single redraw.
316 pub fn refresh(&mut self) {
317 self.pending_effects.push_back(Effect::Refresh);
318 }
319 pub(crate) fn update<R>(&mut self, update: impl FnOnce(&mut Self) -> R) -> R {
320 self.pending_updates += 1;
321 let result = update(self);
322 if !self.flushing_effects && self.pending_updates == 1 {
323 self.flushing_effects = true;
324 self.flush_effects();
325 self.flushing_effects = false;
326 }
327 self.pending_updates -= 1;
328 result
329 }
330
331 pub fn observe<W, E>(
332 &mut self,
333 entity: &E,
334 mut on_notify: impl FnMut(E, &mut AppContext) + 'static,
335 ) -> Subscription
336 where
337 W: 'static,
338 E: Entity<W>,
339 {
340 self.observe_internal(entity, move |e, cx| {
341 on_notify(e, cx);
342 true
343 })
344 }
345
346 pub fn observe_internal<W, E>(
347 &mut self,
348 entity: &E,
349 mut on_notify: impl FnMut(E, &mut AppContext) -> bool + 'static,
350 ) -> Subscription
351 where
352 W: 'static,
353 E: Entity<W>,
354 {
355 let entity_id = entity.entity_id();
356 let handle = entity.downgrade();
357 self.observers.insert(
358 entity_id,
359 Box::new(move |cx| {
360 if let Some(handle) = E::upgrade_from(&handle) {
361 on_notify(handle, cx)
362 } else {
363 false
364 }
365 }),
366 )
367 }
368
369 pub fn subscribe<T, E, Evt>(
370 &mut self,
371 entity: &E,
372 mut on_event: impl FnMut(E, &Evt, &mut AppContext) + 'static,
373 ) -> Subscription
374 where
375 T: 'static + EventEmitter<Evt>,
376 E: Entity<T>,
377 Evt: 'static,
378 {
379 self.subscribe_internal(entity, move |entity, event, cx| {
380 on_event(entity, event, cx);
381 true
382 })
383 }
384
385 pub(crate) fn subscribe_internal<T, E, Evt>(
386 &mut self,
387 entity: &E,
388 mut on_event: impl FnMut(E, &Evt, &mut AppContext) -> bool + 'static,
389 ) -> Subscription
390 where
391 T: 'static + EventEmitter<Evt>,
392 E: Entity<T>,
393 Evt: 'static,
394 {
395 let entity_id = entity.entity_id();
396 let entity = entity.downgrade();
397
398 self.event_listeners.insert(
399 entity_id,
400 (
401 TypeId::of::<Evt>(),
402 Box::new(move |event, cx| {
403 let event: &Evt = event.downcast_ref().expect("invalid event type");
404 if let Some(handle) = E::upgrade_from(&entity) {
405 on_event(handle, event, cx)
406 } else {
407 false
408 }
409 }),
410 ),
411 )
412 }
413
414 pub fn windows(&self) -> Vec<AnyWindowHandle> {
415 self.windows
416 .values()
417 .filter_map(|window| Some(window.as_ref()?.handle.clone()))
418 .collect()
419 }
420
421 /// Opens a new window with the given option and the root view returned by the given function.
422 /// The function is invoked with a `WindowContext`, which can be used to interact with window-specific
423 /// functionality.
424 pub fn open_window<V: Render>(
425 &mut self,
426 options: crate::WindowOptions,
427 build_root_view: impl FnOnce(&mut WindowContext) -> View<V>,
428 ) -> WindowHandle<V> {
429 self.update(|cx| {
430 let id = cx.windows.insert(None);
431 let handle = WindowHandle::new(id);
432 let mut window = Window::new(handle.into(), options, cx);
433 let root_view = build_root_view(&mut WindowContext::new(cx, &mut window));
434 window.root_view.replace(root_view.into());
435 cx.windows.get_mut(id).unwrap().replace(window);
436 handle
437 })
438 }
439
440 /// Instructs the platform to activate the application by bringing it to the foreground.
441 pub fn activate(&self, ignoring_other_apps: bool) {
442 self.platform.activate(ignoring_other_apps);
443 }
444
445 pub fn hide(&self) {
446 self.platform.hide();
447 }
448
449 pub fn hide_other_apps(&self) {
450 self.platform.hide_other_apps();
451 }
452
453 pub fn unhide_other_apps(&self) {
454 self.platform.unhide_other_apps();
455 }
456
457 /// Returns the list of currently active displays.
458 pub fn displays(&self) -> Vec<Rc<dyn PlatformDisplay>> {
459 self.platform.displays()
460 }
461
462 /// Writes data to the platform clipboard.
463 pub fn write_to_clipboard(&self, item: ClipboardItem) {
464 self.platform.write_to_clipboard(item)
465 }
466
467 /// Reads data from the platform clipboard.
468 pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
469 self.platform.read_from_clipboard()
470 }
471
472 /// Writes credentials to the platform keychain.
473 pub fn write_credentials(&self, url: &str, username: &str, password: &[u8]) -> Result<()> {
474 self.platform.write_credentials(url, username, password)
475 }
476
477 /// Reads credentials from the platform keychain.
478 pub fn read_credentials(&self, url: &str) -> Result<Option<(String, Vec<u8>)>> {
479 self.platform.read_credentials(url)
480 }
481
482 /// Deletes credentials from the platform keychain.
483 pub fn delete_credentials(&self, url: &str) -> Result<()> {
484 self.platform.delete_credentials(url)
485 }
486
487 /// Directs the platform's default browser to open the given URL.
488 pub fn open_url(&self, url: &str) {
489 self.platform.open_url(url);
490 }
491
492 pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
493 self.platform.path_for_auxiliary_executable(name)
494 }
495
496 pub fn prompt_for_paths(
497 &self,
498 options: PathPromptOptions,
499 ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
500 self.platform.prompt_for_paths(options)
501 }
502
503 pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
504 self.platform.prompt_for_new_path(directory)
505 }
506
507 pub fn reveal_path(&self, path: &Path) {
508 self.platform.reveal_path(path)
509 }
510
511 pub fn should_auto_hide_scrollbars(&self) -> bool {
512 self.platform.should_auto_hide_scrollbars()
513 }
514
515 pub(crate) fn push_effect(&mut self, effect: Effect) {
516 match &effect {
517 Effect::Notify { emitter } => {
518 if !self.pending_notifications.insert(*emitter) {
519 return;
520 }
521 }
522 Effect::NotifyGlobalObservers { global_type } => {
523 if !self.pending_global_notifications.insert(*global_type) {
524 return;
525 }
526 }
527 _ => {}
528 };
529
530 self.pending_effects.push_back(effect);
531 }
532
533 /// Called at the end of AppContext::update to complete any side effects
534 /// such as notifying observers, emitting events, etc. Effects can themselves
535 /// cause effects, so we continue looping until all effects are processed.
536 fn flush_effects(&mut self) {
537 loop {
538 self.release_dropped_entities();
539 self.release_dropped_focus_handles();
540 if let Some(effect) = self.pending_effects.pop_front() {
541 match effect {
542 Effect::Notify { emitter } => {
543 self.apply_notify_effect(emitter);
544 }
545 Effect::Emit {
546 emitter,
547 event_type,
548 event,
549 } => self.apply_emit_effect(emitter, event_type, event),
550 Effect::FocusChanged {
551 window_handle,
552 focused,
553 } => {
554 self.apply_focus_changed_effect(window_handle, focused);
555 }
556 Effect::Refresh => {
557 self.apply_refresh_effect();
558 }
559 Effect::NotifyGlobalObservers { global_type } => {
560 self.apply_notify_global_observers_effect(global_type);
561 }
562 Effect::Defer { callback } => {
563 self.apply_defer_effect(callback);
564 }
565 }
566 } else {
567 break;
568 }
569 }
570
571 let dirty_window_ids = self
572 .windows
573 .iter()
574 .filter_map(|(_, window)| {
575 let window = window.as_ref().unwrap();
576 if window.dirty {
577 Some(window.handle.clone())
578 } else {
579 None
580 }
581 })
582 .collect::<SmallVec<[_; 8]>>();
583
584 for dirty_window_handle in dirty_window_ids {
585 dirty_window_handle.update(self, |_, cx| cx.draw()).unwrap();
586 }
587 }
588
589 /// Repeatedly called during `flush_effects` to release any entities whose
590 /// reference count has become zero. We invoke any release observers before dropping
591 /// each entity.
592 fn release_dropped_entities(&mut self) {
593 loop {
594 let dropped = self.entities.take_dropped();
595 if dropped.is_empty() {
596 break;
597 }
598
599 for (entity_id, mut entity) in dropped {
600 self.observers.remove(&entity_id);
601 self.event_listeners.remove(&entity_id);
602 for release_callback in self.release_listeners.remove(&entity_id) {
603 release_callback(entity.as_mut(), self);
604 }
605 }
606 }
607 }
608
609 /// Repeatedly called during `flush_effects` to handle a focused handle being dropped.
610 /// For now, we simply blur the window if this happens, but we may want to support invoking
611 /// a window blur handler to restore focus to some logical element.
612 fn release_dropped_focus_handles(&mut self) {
613 for window_handle in self.windows() {
614 window_handle
615 .update(self, |_, cx| {
616 let mut blur_window = false;
617 let focus = cx.window.focus;
618 cx.window.focus_handles.write().retain(|handle_id, count| {
619 if count.load(SeqCst) == 0 {
620 if focus == Some(handle_id) {
621 blur_window = true;
622 }
623 false
624 } else {
625 true
626 }
627 });
628
629 if blur_window {
630 cx.blur();
631 }
632 })
633 .unwrap();
634 }
635 }
636
637 fn apply_notify_effect(&mut self, emitter: EntityId) {
638 self.pending_notifications.remove(&emitter);
639
640 self.observers
641 .clone()
642 .retain(&emitter, |handler| handler(self));
643 }
644
645 fn apply_emit_effect(&mut self, emitter: EntityId, event_type: TypeId, event: Box<dyn Any>) {
646 self.event_listeners
647 .clone()
648 .retain(&emitter, |(stored_type, handler)| {
649 if *stored_type == event_type {
650 handler(event.as_ref(), self)
651 } else {
652 true
653 }
654 });
655 }
656
657 fn apply_focus_changed_effect(
658 &mut self,
659 window_handle: AnyWindowHandle,
660 focused: Option<FocusId>,
661 ) {
662 window_handle
663 .update(self, |_, cx| {
664 // The window might change focus multiple times in an effect cycle.
665 // We only honor effects for the most recently focused handle.
666 if cx.window.focus == focused {
667 // if someone calls focus multiple times in one frame with the same handle
668 // the first apply_focus_changed_effect will have taken the last blur already
669 // and run the rest of this, so we can return.
670 let Some(last_blur) = cx.window.last_blur.take() else {
671 return;
672 };
673
674 let focused = focused
675 .map(|id| FocusHandle::for_id(id, &cx.window.focus_handles).unwrap());
676
677 let blurred =
678 last_blur.and_then(|id| FocusHandle::for_id(id, &cx.window.focus_handles));
679
680 let focus_changed = focused.is_some() || blurred.is_some();
681 let event = FocusEvent { focused, blurred };
682
683 let mut listeners = mem::take(&mut cx.window.current_frame.focus_listeners);
684 if focus_changed {
685 for listener in &mut listeners {
686 listener(&event, cx);
687 }
688 }
689 listeners.extend(cx.window.current_frame.focus_listeners.drain(..));
690 cx.window.current_frame.focus_listeners = listeners;
691
692 if focus_changed {
693 cx.window
694 .focus_listeners
695 .clone()
696 .retain(&(), |listener| listener(&event, cx));
697 }
698 }
699 })
700 .ok();
701 }
702
703 fn apply_refresh_effect(&mut self) {
704 for window in self.windows.values_mut() {
705 if let Some(window) = window.as_mut() {
706 window.dirty = true;
707 }
708 }
709 }
710
711 fn apply_notify_global_observers_effect(&mut self, type_id: TypeId) {
712 self.pending_global_notifications.remove(&type_id);
713 self.global_observers
714 .clone()
715 .retain(&type_id, |observer| observer(self));
716 }
717
718 fn apply_defer_effect(&mut self, callback: Box<dyn FnOnce(&mut Self) + 'static>) {
719 callback(self);
720 }
721
722 /// Creates an `AsyncAppContext`, which can be cloned and has a static lifetime
723 /// so it can be held across `await` points.
724 pub fn to_async(&self) -> AsyncAppContext {
725 AsyncAppContext {
726 app: unsafe { mem::transmute(self.this.clone()) },
727 background_executor: self.background_executor.clone(),
728 foreground_executor: self.foreground_executor.clone(),
729 }
730 }
731
732 /// Obtains a reference to the executor, which can be used to spawn futures.
733 pub fn background_executor(&self) -> &BackgroundExecutor {
734 &self.background_executor
735 }
736
737 /// Obtains a reference to the executor, which can be used to spawn futures.
738 pub fn foreground_executor(&self) -> &ForegroundExecutor {
739 &self.foreground_executor
740 }
741
742 /// Spawns the future returned by the given function on the thread pool. The closure will be invoked
743 /// with AsyncAppContext, which allows the application state to be accessed across await points.
744 pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut) -> Task<R>
745 where
746 Fut: Future<Output = R> + 'static,
747 R: 'static,
748 {
749 self.foreground_executor.spawn(f(self.to_async()))
750 }
751
752 /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
753 /// that are currently on the stack to be returned to the app.
754 pub fn defer(&mut self, f: impl FnOnce(&mut AppContext) + 'static) {
755 self.push_effect(Effect::Defer {
756 callback: Box::new(f),
757 });
758 }
759
760 /// Accessor for the application's asset source, which is provided when constructing the `App`.
761 pub fn asset_source(&self) -> &Arc<dyn AssetSource> {
762 &self.asset_source
763 }
764
765 /// Accessor for the text system.
766 pub fn text_system(&self) -> &Arc<TextSystem> {
767 &self.text_system
768 }
769
770 /// The current text style. Which is composed of all the style refinements provided to `with_text_style`.
771 pub fn text_style(&self) -> TextStyle {
772 let mut style = TextStyle::default();
773 for refinement in &self.text_style_stack {
774 style.refine(refinement);
775 }
776 style
777 }
778
779 /// Check whether a global of the given type has been assigned.
780 pub fn has_global<G: 'static>(&self) -> bool {
781 self.globals_by_type.contains_key(&TypeId::of::<G>())
782 }
783
784 /// Access the global of the given type. Panics if a global for that type has not been assigned.
785 #[track_caller]
786 pub fn global<G: 'static>(&self) -> &G {
787 self.globals_by_type
788 .get(&TypeId::of::<G>())
789 .map(|any_state| any_state.downcast_ref::<G>().unwrap())
790 .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
791 .unwrap()
792 }
793
794 /// Access the global of the given type if a value has been assigned.
795 pub fn try_global<G: 'static>(&self) -> Option<&G> {
796 self.globals_by_type
797 .get(&TypeId::of::<G>())
798 .map(|any_state| any_state.downcast_ref::<G>().unwrap())
799 }
800
801 /// Access the global of the given type mutably. Panics if a global for that type has not been assigned.
802 #[track_caller]
803 pub fn global_mut<G: 'static>(&mut self) -> &mut G {
804 let global_type = TypeId::of::<G>();
805 self.push_effect(Effect::NotifyGlobalObservers { global_type });
806 self.globals_by_type
807 .get_mut(&global_type)
808 .and_then(|any_state| any_state.downcast_mut::<G>())
809 .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
810 .unwrap()
811 }
812
813 /// Access the global of the given type mutably. A default value is assigned if a global of this type has not
814 /// yet been assigned.
815 pub fn default_global<G: 'static + Default>(&mut self) -> &mut G {
816 let global_type = TypeId::of::<G>();
817 self.push_effect(Effect::NotifyGlobalObservers { global_type });
818 self.globals_by_type
819 .entry(global_type)
820 .or_insert_with(|| Box::new(G::default()))
821 .downcast_mut::<G>()
822 .unwrap()
823 }
824
825 /// Set the value of the global of the given type.
826 pub fn set_global<G: Any>(&mut self, global: G) {
827 let global_type = TypeId::of::<G>();
828 self.push_effect(Effect::NotifyGlobalObservers { global_type });
829 self.globals_by_type.insert(global_type, Box::new(global));
830 }
831
832 /// Clear all stored globals. Does not notify global observers.
833 #[cfg(any(test, feature = "test-support"))]
834 pub fn clear_globals(&mut self) {
835 self.globals_by_type.drain();
836 }
837
838 /// Remove the global of the given type from the app context. Does not notify global observers.
839 #[cfg(any(test, feature = "test-support"))]
840 pub fn remove_global<G: Any>(&mut self) -> G {
841 let global_type = TypeId::of::<G>();
842 *self
843 .globals_by_type
844 .remove(&global_type)
845 .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<G>()))
846 .downcast()
847 .unwrap()
848 }
849
850 /// Update the global of the given type with a closure. Unlike `global_mut`, this method provides
851 /// your closure with mutable access to the `AppContext` and the global simultaneously.
852 pub fn update_global<G: 'static, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R {
853 let mut global = self.lease_global::<G>();
854 let result = f(&mut global, self);
855 self.end_global_lease(global);
856 result
857 }
858
859 /// Register a callback to be invoked when a global of the given type is updated.
860 pub fn observe_global<G: 'static>(
861 &mut self,
862 mut f: impl FnMut(&mut Self) + 'static,
863 ) -> Subscription {
864 self.global_observers.insert(
865 TypeId::of::<G>(),
866 Box::new(move |cx| {
867 f(cx);
868 true
869 }),
870 )
871 }
872
873 /// Move the global of the given type to the stack.
874 pub(crate) fn lease_global<G: 'static>(&mut self) -> GlobalLease<G> {
875 GlobalLease::new(
876 self.globals_by_type
877 .remove(&TypeId::of::<G>())
878 .ok_or_else(|| anyhow!("no global registered of type {}", type_name::<G>()))
879 .unwrap(),
880 )
881 }
882
883 /// Restore the global of the given type after it is moved to the stack.
884 pub(crate) fn end_global_lease<G: 'static>(&mut self, lease: GlobalLease<G>) {
885 let global_type = TypeId::of::<G>();
886 self.push_effect(Effect::NotifyGlobalObservers { global_type });
887 self.globals_by_type.insert(global_type, lease.global);
888 }
889
890 pub fn observe_new_views<V: 'static>(
891 &mut self,
892 on_new: impl 'static + Fn(&mut V, &mut ViewContext<V>),
893 ) -> Subscription {
894 self.new_view_observers.insert(
895 TypeId::of::<V>(),
896 Box::new(move |any_view: AnyView, cx: &mut WindowContext| {
897 any_view
898 .downcast::<V>()
899 .unwrap()
900 .update(cx, |view_state, cx| {
901 on_new(view_state, cx);
902 })
903 }),
904 )
905 }
906
907 pub fn observe_release<E, T>(
908 &mut self,
909 handle: &E,
910 on_release: impl FnOnce(&mut T, &mut AppContext) + 'static,
911 ) -> Subscription
912 where
913 E: Entity<T>,
914 T: 'static,
915 {
916 self.release_listeners.insert(
917 handle.entity_id(),
918 Box::new(move |entity, cx| {
919 let entity = entity.downcast_mut().expect("invalid entity type");
920 on_release(entity, cx)
921 }),
922 )
923 }
924
925 pub(crate) fn push_text_style(&mut self, text_style: TextStyleRefinement) {
926 self.text_style_stack.push(text_style);
927 }
928
929 pub(crate) fn pop_text_style(&mut self) {
930 self.text_style_stack.pop();
931 }
932
933 /// Register key bindings.
934 pub fn bind_keys(&mut self, bindings: impl IntoIterator<Item = KeyBinding>) {
935 self.keymap.lock().add_bindings(bindings);
936 self.pending_effects.push_back(Effect::Refresh);
937 }
938
939 /// Register a global listener for actions invoked via the keyboard.
940 pub fn on_action<A: Action>(&mut self, listener: impl Fn(&A, &mut Self) + 'static) {
941 self.global_action_listeners
942 .entry(TypeId::of::<A>())
943 .or_default()
944 .push(Box::new(move |action, phase, cx| {
945 if phase == DispatchPhase::Bubble {
946 let action = action.as_any().downcast_ref().unwrap();
947 listener(action, cx)
948 }
949 }));
950 }
951
952 /// Event handlers propagate events by default. Call this method to stop dispatching to
953 /// event handlers with a lower z-index (mouse) or higher in the tree (keyboard). This is
954 /// the opposite of [propagate]. It's also possible to cancel a call to [propagate] by
955 /// calling this method before effects are flushed.
956 pub fn stop_propagation(&mut self) {
957 self.propagate_event = false;
958 }
959
960 /// Action handlers stop propagation by default during the bubble phase of action dispatch
961 /// dispatching to action handlers higher in the element tree. This is the opposite of
962 /// [stop_propagation]. It's also possible to cancel a call to [stop_propagate] by calling
963 /// this method before effects are flushed.
964 pub fn propagate(&mut self) {
965 self.propagate_event = true;
966 }
967}
968
969impl Context for AppContext {
970 type Result<T> = T;
971
972 /// Build an entity that is owned by the application. The given function will be invoked with
973 /// a `ModelContext` and must return an object representing the entity. A `Model` will be returned
974 /// which can be used to access the entity in a context.
975 fn build_model<T: 'static>(
976 &mut self,
977 build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
978 ) -> Model<T> {
979 self.update(|cx| {
980 let slot = cx.entities.reserve();
981 let entity = build_model(&mut ModelContext::new(cx, slot.downgrade()));
982 cx.entities.insert(slot, entity)
983 })
984 }
985
986 /// Update the entity referenced by the given model. The function is passed a mutable reference to the
987 /// entity along with a `ModelContext` for the entity.
988 fn update_model<T: 'static, R>(
989 &mut self,
990 model: &Model<T>,
991 update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
992 ) -> R {
993 self.update(|cx| {
994 let mut entity = cx.entities.lease(model);
995 let result = update(&mut entity, &mut ModelContext::new(cx, model.downgrade()));
996 cx.entities.end_lease(entity);
997 result
998 })
999 }
1000
1001 fn update_window<T, F>(&mut self, handle: AnyWindowHandle, update: F) -> Result<T>
1002 where
1003 F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1004 {
1005 self.update(|cx| {
1006 let mut window = cx
1007 .windows
1008 .get_mut(handle.id)
1009 .ok_or_else(|| anyhow!("window not found"))?
1010 .take()
1011 .unwrap();
1012
1013 let root_view = window.root_view.clone().unwrap();
1014 let result = update(root_view, &mut WindowContext::new(cx, &mut window));
1015
1016 if !window.removed {
1017 cx.windows
1018 .get_mut(handle.id)
1019 .ok_or_else(|| anyhow!("window not found"))?
1020 .replace(window);
1021 }
1022
1023 Ok(result)
1024 })
1025 }
1026
1027 fn read_model<T, R>(
1028 &self,
1029 handle: &Model<T>,
1030 read: impl FnOnce(&T, &AppContext) -> R,
1031 ) -> Self::Result<R>
1032 where
1033 T: 'static,
1034 {
1035 let entity = self.entities.read(handle);
1036 read(entity, self)
1037 }
1038
1039 fn read_window<T, R>(
1040 &self,
1041 window: &WindowHandle<T>,
1042 read: impl FnOnce(View<T>, &AppContext) -> R,
1043 ) -> Result<R>
1044 where
1045 T: 'static,
1046 {
1047 let window = self
1048 .windows
1049 .get(window.id)
1050 .ok_or_else(|| anyhow!("window not found"))?
1051 .as_ref()
1052 .unwrap();
1053
1054 let root_view = window.root_view.clone().unwrap();
1055 let view = root_view
1056 .downcast::<T>()
1057 .map_err(|_| anyhow!("root view's type has changed"))?;
1058
1059 Ok(read(view, self))
1060 }
1061}
1062
1063/// These effects are processed at the end of each application update cycle.
1064pub(crate) enum Effect {
1065 Notify {
1066 emitter: EntityId,
1067 },
1068 Emit {
1069 emitter: EntityId,
1070 event_type: TypeId,
1071 event: Box<dyn Any>,
1072 },
1073 FocusChanged {
1074 window_handle: AnyWindowHandle,
1075 focused: Option<FocusId>,
1076 },
1077 Refresh,
1078 NotifyGlobalObservers {
1079 global_type: TypeId,
1080 },
1081 Defer {
1082 callback: Box<dyn FnOnce(&mut AppContext) + 'static>,
1083 },
1084}
1085
1086/// Wraps a global variable value during `update_global` while the value has been moved to the stack.
1087pub(crate) struct GlobalLease<G: 'static> {
1088 global: AnyBox,
1089 global_type: PhantomData<G>,
1090}
1091
1092impl<G: 'static> GlobalLease<G> {
1093 fn new(global: AnyBox) -> Self {
1094 GlobalLease {
1095 global,
1096 global_type: PhantomData,
1097 }
1098 }
1099}
1100
1101impl<G: 'static> Deref for GlobalLease<G> {
1102 type Target = G;
1103
1104 fn deref(&self) -> &Self::Target {
1105 self.global.downcast_ref().unwrap()
1106 }
1107}
1108
1109impl<G: 'static> DerefMut for GlobalLease<G> {
1110 fn deref_mut(&mut self) -> &mut Self::Target {
1111 self.global.downcast_mut().unwrap()
1112 }
1113}
1114
1115/// Contains state associated with an active drag operation, started by dragging an element
1116/// within the window or by dragging into the app from the underlying platform.
1117pub struct AnyDrag {
1118 pub view: AnyView,
1119 pub cursor_offset: Point<Pixels>,
1120}
1121
1122#[derive(Clone)]
1123pub(crate) struct AnyTooltip {
1124 pub view: AnyView,
1125 pub cursor_offset: Point<Pixels>,
1126}