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 Rc::new_cyclic(|this| AppCell {
238 app: RefCell::new(AppContext {
239 this: this.clone(),
240 platform,
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
275 /// Quit the application gracefully. Handlers registered with `ModelContext::on_app_quit`
276 /// will be given 100ms to complete before exiting.
277 pub fn quit(&mut self) {
278 let mut futures = Vec::new();
279
280 for observer in self.quit_observers.remove(&()) {
281 futures.push(observer(self));
282 }
283
284 self.windows.clear();
285 self.flush_effects();
286
287 let futures = futures::future::join_all(futures);
288 if self
289 .background_executor
290 .block_with_timeout(Duration::from_millis(100), futures)
291 .is_err()
292 {
293 log::error!("timed out waiting on app_will_quit");
294 }
295
296 self.globals_by_type.clear();
297 }
298
299 pub fn app_metadata(&self) -> AppMetadata {
300 self.app_metadata.clone()
301 }
302
303 /// Schedules all windows in the application to be redrawn. This can be called
304 /// multiple times in an update cycle and still result in a single redraw.
305 pub fn refresh(&mut self) {
306 self.pending_effects.push_back(Effect::Refresh);
307 }
308 pub(crate) fn update<R>(&mut self, update: impl FnOnce(&mut Self) -> R) -> R {
309 self.pending_updates += 1;
310 let result = update(self);
311 if !self.flushing_effects && self.pending_updates == 1 {
312 self.flushing_effects = true;
313 self.flush_effects();
314 self.flushing_effects = false;
315 }
316 self.pending_updates -= 1;
317 result
318 }
319
320 pub fn observe<W, E>(
321 &mut self,
322 entity: &E,
323 mut on_notify: impl FnMut(E, &mut AppContext) + 'static,
324 ) -> Subscription
325 where
326 W: 'static,
327 E: Entity<W>,
328 {
329 self.observe_internal(entity, move |e, cx| {
330 on_notify(e, cx);
331 true
332 })
333 }
334
335 pub fn observe_internal<W, E>(
336 &mut self,
337 entity: &E,
338 mut on_notify: impl FnMut(E, &mut AppContext) -> bool + 'static,
339 ) -> Subscription
340 where
341 W: 'static,
342 E: Entity<W>,
343 {
344 let entity_id = entity.entity_id();
345 let handle = entity.downgrade();
346 self.observers.insert(
347 entity_id,
348 Box::new(move |cx| {
349 if let Some(handle) = E::upgrade_from(&handle) {
350 on_notify(handle, cx)
351 } else {
352 false
353 }
354 }),
355 )
356 }
357
358 pub fn subscribe<T, E, Evt>(
359 &mut self,
360 entity: &E,
361 mut on_event: impl FnMut(E, &Evt, &mut AppContext) + 'static,
362 ) -> Subscription
363 where
364 T: 'static + EventEmitter<Evt>,
365 E: Entity<T>,
366 Evt: 'static,
367 {
368 self.subscribe_internal(entity, move |entity, event, cx| {
369 on_event(entity, event, cx);
370 true
371 })
372 }
373
374 pub(crate) fn subscribe_internal<T, E, Evt>(
375 &mut self,
376 entity: &E,
377 mut on_event: impl FnMut(E, &Evt, &mut AppContext) -> bool + 'static,
378 ) -> Subscription
379 where
380 T: 'static + EventEmitter<Evt>,
381 E: Entity<T>,
382 Evt: 'static,
383 {
384 let entity_id = entity.entity_id();
385 let entity = entity.downgrade();
386
387 self.event_listeners.insert(
388 entity_id,
389 (
390 TypeId::of::<Evt>(),
391 Box::new(move |event, cx| {
392 let event: &Evt = event.downcast_ref().expect("invalid event type");
393 if let Some(handle) = E::upgrade_from(&entity) {
394 on_event(handle, event, cx)
395 } else {
396 false
397 }
398 }),
399 ),
400 )
401 }
402
403 pub fn windows(&self) -> Vec<AnyWindowHandle> {
404 self.windows
405 .values()
406 .filter_map(|window| Some(window.as_ref()?.handle.clone()))
407 .collect()
408 }
409
410 /// Opens a new window with the given option and the root view returned by the given function.
411 /// The function is invoked with a `WindowContext`, which can be used to interact with window-specific
412 /// functionality.
413 pub fn open_window<V: Render>(
414 &mut self,
415 options: crate::WindowOptions,
416 build_root_view: impl FnOnce(&mut WindowContext) -> View<V>,
417 ) -> WindowHandle<V> {
418 self.update(|cx| {
419 let id = cx.windows.insert(None);
420 let handle = WindowHandle::new(id);
421 let mut window = Window::new(handle.into(), options, cx);
422 let root_view = build_root_view(&mut WindowContext::new(cx, &mut window));
423 window.root_view.replace(root_view.into());
424 cx.windows.get_mut(id).unwrap().replace(window);
425 handle
426 })
427 }
428
429 /// Instructs the platform to activate the application by bringing it to the foreground.
430 pub fn activate(&self, ignoring_other_apps: bool) {
431 self.platform.activate(ignoring_other_apps);
432 }
433
434 pub fn hide(&self) {
435 self.platform.hide();
436 }
437
438 pub fn hide_other_apps(&self) {
439 self.platform.hide_other_apps();
440 }
441
442 pub fn unhide_other_apps(&self) {
443 self.platform.unhide_other_apps();
444 }
445
446 /// Returns the list of currently active displays.
447 pub fn displays(&self) -> Vec<Rc<dyn PlatformDisplay>> {
448 self.platform.displays()
449 }
450
451 /// Writes data to the platform clipboard.
452 pub fn write_to_clipboard(&self, item: ClipboardItem) {
453 self.platform.write_to_clipboard(item)
454 }
455
456 /// Reads data from the platform clipboard.
457 pub fn read_from_clipboard(&self) -> Option<ClipboardItem> {
458 self.platform.read_from_clipboard()
459 }
460
461 /// Writes credentials to the platform keychain.
462 pub fn write_credentials(&self, url: &str, username: &str, password: &[u8]) -> Result<()> {
463 self.platform.write_credentials(url, username, password)
464 }
465
466 /// Reads credentials from the platform keychain.
467 pub fn read_credentials(&self, url: &str) -> Result<Option<(String, Vec<u8>)>> {
468 self.platform.read_credentials(url)
469 }
470
471 /// Deletes credentials from the platform keychain.
472 pub fn delete_credentials(&self, url: &str) -> Result<()> {
473 self.platform.delete_credentials(url)
474 }
475
476 /// Directs the platform's default browser to open the given URL.
477 pub fn open_url(&self, url: &str) {
478 self.platform.open_url(url);
479 }
480
481 pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
482 self.platform.path_for_auxiliary_executable(name)
483 }
484
485 pub fn prompt_for_paths(
486 &self,
487 options: PathPromptOptions,
488 ) -> oneshot::Receiver<Option<Vec<PathBuf>>> {
489 self.platform.prompt_for_paths(options)
490 }
491
492 pub fn prompt_for_new_path(&self, directory: &Path) -> oneshot::Receiver<Option<PathBuf>> {
493 self.platform.prompt_for_new_path(directory)
494 }
495
496 pub fn reveal_path(&self, path: &Path) {
497 self.platform.reveal_path(path)
498 }
499
500 pub fn should_auto_hide_scrollbars(&self) -> bool {
501 self.platform.should_auto_hide_scrollbars()
502 }
503
504 pub(crate) fn push_effect(&mut self, effect: Effect) {
505 match &effect {
506 Effect::Notify { emitter } => {
507 if !self.pending_notifications.insert(*emitter) {
508 return;
509 }
510 }
511 Effect::NotifyGlobalObservers { global_type } => {
512 if !self.pending_global_notifications.insert(*global_type) {
513 return;
514 }
515 }
516 _ => {}
517 };
518
519 self.pending_effects.push_back(effect);
520 }
521
522 /// Called at the end of AppContext::update to complete any side effects
523 /// such as notifying observers, emitting events, etc. Effects can themselves
524 /// cause effects, so we continue looping until all effects are processed.
525 fn flush_effects(&mut self) {
526 loop {
527 self.release_dropped_entities();
528 self.release_dropped_focus_handles();
529 if let Some(effect) = self.pending_effects.pop_front() {
530 match effect {
531 Effect::Notify { emitter } => {
532 self.apply_notify_effect(emitter);
533 }
534 Effect::Emit {
535 emitter,
536 event_type,
537 event,
538 } => self.apply_emit_effect(emitter, event_type, event),
539 Effect::FocusChanged {
540 window_handle,
541 focused,
542 } => {
543 self.apply_focus_changed_effect(window_handle, focused);
544 }
545 Effect::Refresh => {
546 self.apply_refresh_effect();
547 }
548 Effect::NotifyGlobalObservers { global_type } => {
549 self.apply_notify_global_observers_effect(global_type);
550 }
551 Effect::Defer { callback } => {
552 self.apply_defer_effect(callback);
553 }
554 }
555 } else {
556 break;
557 }
558 }
559
560 let dirty_window_ids = self
561 .windows
562 .iter()
563 .filter_map(|(_, window)| {
564 let window = window.as_ref().unwrap();
565 if window.dirty {
566 Some(window.handle.clone())
567 } else {
568 None
569 }
570 })
571 .collect::<SmallVec<[_; 8]>>();
572
573 for dirty_window_handle in dirty_window_ids {
574 dirty_window_handle.update(self, |_, cx| cx.draw()).unwrap();
575 }
576 }
577
578 /// Repeatedly called during `flush_effects` to release any entities whose
579 /// reference count has become zero. We invoke any release observers before dropping
580 /// each entity.
581 fn release_dropped_entities(&mut self) {
582 loop {
583 let dropped = self.entities.take_dropped();
584 if dropped.is_empty() {
585 break;
586 }
587
588 for (entity_id, mut entity) in dropped {
589 self.observers.remove(&entity_id);
590 self.event_listeners.remove(&entity_id);
591 for release_callback in self.release_listeners.remove(&entity_id) {
592 release_callback(entity.as_mut(), self);
593 }
594 }
595 }
596 }
597
598 /// Repeatedly called during `flush_effects` to handle a focused handle being dropped.
599 /// For now, we simply blur the window if this happens, but we may want to support invoking
600 /// a window blur handler to restore focus to some logical element.
601 fn release_dropped_focus_handles(&mut self) {
602 for window_handle in self.windows() {
603 window_handle
604 .update(self, |_, cx| {
605 let mut blur_window = false;
606 let focus = cx.window.focus;
607 cx.window.focus_handles.write().retain(|handle_id, count| {
608 if count.load(SeqCst) == 0 {
609 if focus == Some(handle_id) {
610 blur_window = true;
611 }
612 false
613 } else {
614 true
615 }
616 });
617
618 if blur_window {
619 cx.blur();
620 }
621 })
622 .unwrap();
623 }
624 }
625
626 fn apply_notify_effect(&mut self, emitter: EntityId) {
627 self.pending_notifications.remove(&emitter);
628
629 self.observers
630 .clone()
631 .retain(&emitter, |handler| handler(self));
632 }
633
634 fn apply_emit_effect(&mut self, emitter: EntityId, event_type: TypeId, event: Box<dyn Any>) {
635 self.event_listeners
636 .clone()
637 .retain(&emitter, |(stored_type, handler)| {
638 if *stored_type == event_type {
639 handler(event.as_ref(), self)
640 } else {
641 true
642 }
643 });
644 }
645
646 fn apply_focus_changed_effect(
647 &mut self,
648 window_handle: AnyWindowHandle,
649 focused: Option<FocusId>,
650 ) {
651 window_handle
652 .update(self, |_, cx| {
653 // The window might change focus multiple times in an effect cycle.
654 // We only honor effects for the most recently focused handle.
655 if cx.window.focus == focused {
656 // if someone calls focus multiple times in one frame with the same handle
657 // the first apply_focus_changed_effect will have taken the last blur already
658 // and run the rest of this, so we can return.
659 let Some(last_blur) = cx.window.last_blur.take() else {
660 return;
661 };
662
663 let focused = focused
664 .map(|id| FocusHandle::for_id(id, &cx.window.focus_handles).unwrap());
665
666 let blurred =
667 last_blur.and_then(|id| FocusHandle::for_id(id, &cx.window.focus_handles));
668
669 let focus_changed = focused.is_some() || blurred.is_some();
670 let event = FocusEvent { focused, blurred };
671
672 let mut listeners = mem::take(&mut cx.window.current_frame.focus_listeners);
673 if focus_changed {
674 for listener in &mut listeners {
675 listener(&event, cx);
676 }
677 }
678 listeners.extend(cx.window.current_frame.focus_listeners.drain(..));
679 cx.window.current_frame.focus_listeners = listeners;
680
681 if focus_changed {
682 cx.window
683 .focus_listeners
684 .clone()
685 .retain(&(), |listener| listener(&event, cx));
686 }
687 }
688 })
689 .ok();
690 }
691
692 fn apply_refresh_effect(&mut self) {
693 for window in self.windows.values_mut() {
694 if let Some(window) = window.as_mut() {
695 window.dirty = true;
696 }
697 }
698 }
699
700 fn apply_notify_global_observers_effect(&mut self, type_id: TypeId) {
701 self.pending_global_notifications.remove(&type_id);
702 self.global_observers
703 .clone()
704 .retain(&type_id, |observer| observer(self));
705 }
706
707 fn apply_defer_effect(&mut self, callback: Box<dyn FnOnce(&mut Self) + 'static>) {
708 callback(self);
709 }
710
711 /// Creates an `AsyncAppContext`, which can be cloned and has a static lifetime
712 /// so it can be held across `await` points.
713 pub fn to_async(&self) -> AsyncAppContext {
714 AsyncAppContext {
715 app: unsafe { mem::transmute(self.this.clone()) },
716 background_executor: self.background_executor.clone(),
717 foreground_executor: self.foreground_executor.clone(),
718 }
719 }
720
721 /// Obtains a reference to the executor, which can be used to spawn futures.
722 pub fn background_executor(&self) -> &BackgroundExecutor {
723 &self.background_executor
724 }
725
726 /// Obtains a reference to the executor, which can be used to spawn futures.
727 pub fn foreground_executor(&self) -> &ForegroundExecutor {
728 &self.foreground_executor
729 }
730
731 /// Spawns the future returned by the given function on the thread pool. The closure will be invoked
732 /// with AsyncAppContext, which allows the application state to be accessed across await points.
733 pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut) -> Task<R>
734 where
735 Fut: Future<Output = R> + 'static,
736 R: 'static,
737 {
738 self.foreground_executor.spawn(f(self.to_async()))
739 }
740
741 /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
742 /// that are currently on the stack to be returned to the app.
743 pub fn defer(&mut self, f: impl FnOnce(&mut AppContext) + 'static) {
744 self.push_effect(Effect::Defer {
745 callback: Box::new(f),
746 });
747 }
748
749 /// Accessor for the application's asset source, which is provided when constructing the `App`.
750 pub fn asset_source(&self) -> &Arc<dyn AssetSource> {
751 &self.asset_source
752 }
753
754 /// Accessor for the text system.
755 pub fn text_system(&self) -> &Arc<TextSystem> {
756 &self.text_system
757 }
758
759 /// The current text style. Which is composed of all the style refinements provided to `with_text_style`.
760 pub fn text_style(&self) -> TextStyle {
761 let mut style = TextStyle::default();
762 for refinement in &self.text_style_stack {
763 style.refine(refinement);
764 }
765 style
766 }
767
768 /// Check whether a global of the given type has been assigned.
769 pub fn has_global<G: 'static>(&self) -> bool {
770 self.globals_by_type.contains_key(&TypeId::of::<G>())
771 }
772
773 /// Access the global of the given type. Panics if a global for that type has not been assigned.
774 #[track_caller]
775 pub fn global<G: 'static>(&self) -> &G {
776 self.globals_by_type
777 .get(&TypeId::of::<G>())
778 .map(|any_state| any_state.downcast_ref::<G>().unwrap())
779 .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
780 .unwrap()
781 }
782
783 /// Access the global of the given type if a value has been assigned.
784 pub fn try_global<G: 'static>(&self) -> Option<&G> {
785 self.globals_by_type
786 .get(&TypeId::of::<G>())
787 .map(|any_state| any_state.downcast_ref::<G>().unwrap())
788 }
789
790 /// Access the global of the given type mutably. Panics if a global for that type has not been assigned.
791 #[track_caller]
792 pub fn global_mut<G: 'static>(&mut self) -> &mut G {
793 let global_type = TypeId::of::<G>();
794 self.push_effect(Effect::NotifyGlobalObservers { global_type });
795 self.globals_by_type
796 .get_mut(&global_type)
797 .and_then(|any_state| any_state.downcast_mut::<G>())
798 .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
799 .unwrap()
800 }
801
802 /// Access the global of the given type mutably. A default value is assigned if a global of this type has not
803 /// yet been assigned.
804 pub fn default_global<G: 'static + Default>(&mut self) -> &mut G {
805 let global_type = TypeId::of::<G>();
806 self.push_effect(Effect::NotifyGlobalObservers { global_type });
807 self.globals_by_type
808 .entry(global_type)
809 .or_insert_with(|| Box::new(G::default()))
810 .downcast_mut::<G>()
811 .unwrap()
812 }
813
814 /// Set the value of the global of the given type.
815 pub fn set_global<G: Any>(&mut self, global: G) {
816 let global_type = TypeId::of::<G>();
817 self.push_effect(Effect::NotifyGlobalObservers { global_type });
818 self.globals_by_type.insert(global_type, Box::new(global));
819 }
820
821 /// Clear all stored globals. Does not notify global observers.
822 #[cfg(any(test, feature = "test-support"))]
823 pub fn clear_globals(&mut self) {
824 self.globals_by_type.drain();
825 }
826
827 /// Remove the global of the given type from the app context. Does not notify global observers.
828 #[cfg(any(test, feature = "test-support"))]
829 pub fn remove_global<G: Any>(&mut self) -> G {
830 let global_type = TypeId::of::<G>();
831 *self
832 .globals_by_type
833 .remove(&global_type)
834 .unwrap_or_else(|| panic!("no global added for {}", std::any::type_name::<G>()))
835 .downcast()
836 .unwrap()
837 }
838
839 /// Update the global of the given type with a closure. Unlike `global_mut`, this method provides
840 /// your closure with mutable access to the `AppContext` and the global simultaneously.
841 pub fn update_global<G: 'static, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R {
842 let mut global = self.lease_global::<G>();
843 let result = f(&mut global, self);
844 self.end_global_lease(global);
845 result
846 }
847
848 /// Register a callback to be invoked when a global of the given type is updated.
849 pub fn observe_global<G: 'static>(
850 &mut self,
851 mut f: impl FnMut(&mut Self) + 'static,
852 ) -> Subscription {
853 self.global_observers.insert(
854 TypeId::of::<G>(),
855 Box::new(move |cx| {
856 f(cx);
857 true
858 }),
859 )
860 }
861
862 /// Move the global of the given type to the stack.
863 pub(crate) fn lease_global<G: 'static>(&mut self) -> GlobalLease<G> {
864 GlobalLease::new(
865 self.globals_by_type
866 .remove(&TypeId::of::<G>())
867 .ok_or_else(|| anyhow!("no global registered of type {}", type_name::<G>()))
868 .unwrap(),
869 )
870 }
871
872 /// Restore the global of the given type after it is moved to the stack.
873 pub(crate) fn end_global_lease<G: 'static>(&mut self, lease: GlobalLease<G>) {
874 let global_type = TypeId::of::<G>();
875 self.push_effect(Effect::NotifyGlobalObservers { global_type });
876 self.globals_by_type.insert(global_type, lease.global);
877 }
878
879 pub fn observe_new_views<V: 'static>(
880 &mut self,
881 on_new: impl 'static + Fn(&mut V, &mut ViewContext<V>),
882 ) -> Subscription {
883 self.new_view_observers.insert(
884 TypeId::of::<V>(),
885 Box::new(move |any_view: AnyView, cx: &mut WindowContext| {
886 any_view
887 .downcast::<V>()
888 .unwrap()
889 .update(cx, |view_state, cx| {
890 on_new(view_state, cx);
891 })
892 }),
893 )
894 }
895
896 pub fn observe_release<E, T>(
897 &mut self,
898 handle: &E,
899 on_release: impl FnOnce(&mut T, &mut AppContext) + 'static,
900 ) -> Subscription
901 where
902 E: Entity<T>,
903 T: 'static,
904 {
905 self.release_listeners.insert(
906 handle.entity_id(),
907 Box::new(move |entity, cx| {
908 let entity = entity.downcast_mut().expect("invalid entity type");
909 on_release(entity, cx)
910 }),
911 )
912 }
913
914 pub(crate) fn push_text_style(&mut self, text_style: TextStyleRefinement) {
915 self.text_style_stack.push(text_style);
916 }
917
918 pub(crate) fn pop_text_style(&mut self) {
919 self.text_style_stack.pop();
920 }
921
922 /// Register key bindings.
923 pub fn bind_keys(&mut self, bindings: impl IntoIterator<Item = KeyBinding>) {
924 self.keymap.lock().add_bindings(bindings);
925 self.pending_effects.push_back(Effect::Refresh);
926 }
927
928 /// Register a global listener for actions invoked via the keyboard.
929 pub fn on_action<A: Action>(&mut self, listener: impl Fn(&A, &mut Self) + 'static) {
930 self.global_action_listeners
931 .entry(TypeId::of::<A>())
932 .or_default()
933 .push(Box::new(move |action, phase, cx| {
934 if phase == DispatchPhase::Bubble {
935 let action = action.as_any().downcast_ref().unwrap();
936 listener(action, cx)
937 }
938 }));
939 }
940
941 /// Event handlers propagate events by default. Call this method to stop dispatching to
942 /// event handlers with a lower z-index (mouse) or higher in the tree (keyboard). This is
943 /// the opposite of [propagate]. It's also possible to cancel a call to [propagate] by
944 /// calling this method before effects are flushed.
945 pub fn stop_propagation(&mut self) {
946 self.propagate_event = false;
947 }
948
949 /// Action handlers stop propagation by default during the bubble phase of action dispatch
950 /// dispatching to action handlers higher in the element tree. This is the opposite of
951 /// [stop_propagation]. It's also possible to cancel a call to [stop_propagate] by calling
952 /// this method before effects are flushed.
953 pub fn propagate(&mut self) {
954 self.propagate_event = true;
955 }
956}
957
958impl Context for AppContext {
959 type Result<T> = T;
960
961 /// Build an entity that is owned by the application. The given function will be invoked with
962 /// a `ModelContext` and must return an object representing the entity. A `Model` will be returned
963 /// which can be used to access the entity in a context.
964 fn build_model<T: 'static>(
965 &mut self,
966 build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
967 ) -> Model<T> {
968 self.update(|cx| {
969 let slot = cx.entities.reserve();
970 let entity = build_model(&mut ModelContext::new(cx, slot.downgrade()));
971 cx.entities.insert(slot, entity)
972 })
973 }
974
975 /// Update the entity referenced by the given model. The function is passed a mutable reference to the
976 /// entity along with a `ModelContext` for the entity.
977 fn update_model<T: 'static, R>(
978 &mut self,
979 model: &Model<T>,
980 update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
981 ) -> R {
982 self.update(|cx| {
983 let mut entity = cx.entities.lease(model);
984 let result = update(&mut entity, &mut ModelContext::new(cx, model.downgrade()));
985 cx.entities.end_lease(entity);
986 result
987 })
988 }
989
990 fn update_window<T, F>(&mut self, handle: AnyWindowHandle, update: F) -> Result<T>
991 where
992 F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
993 {
994 self.update(|cx| {
995 let mut window = cx
996 .windows
997 .get_mut(handle.id)
998 .ok_or_else(|| anyhow!("window not found"))?
999 .take()
1000 .unwrap();
1001
1002 let root_view = window.root_view.clone().unwrap();
1003 let result = update(root_view, &mut WindowContext::new(cx, &mut window));
1004
1005 if !window.removed {
1006 cx.windows
1007 .get_mut(handle.id)
1008 .ok_or_else(|| anyhow!("window not found"))?
1009 .replace(window);
1010 }
1011
1012 Ok(result)
1013 })
1014 }
1015
1016 fn read_model<T, R>(
1017 &self,
1018 handle: &Model<T>,
1019 read: impl FnOnce(&T, &AppContext) -> R,
1020 ) -> Self::Result<R>
1021 where
1022 T: 'static,
1023 {
1024 let entity = self.entities.read(handle);
1025 read(entity, self)
1026 }
1027
1028 fn read_window<T, R>(
1029 &self,
1030 window: &WindowHandle<T>,
1031 read: impl FnOnce(View<T>, &AppContext) -> R,
1032 ) -> Result<R>
1033 where
1034 T: 'static,
1035 {
1036 let window = self
1037 .windows
1038 .get(window.id)
1039 .ok_or_else(|| anyhow!("window not found"))?
1040 .as_ref()
1041 .unwrap();
1042
1043 let root_view = window.root_view.clone().unwrap();
1044 let view = root_view
1045 .downcast::<T>()
1046 .map_err(|_| anyhow!("root view's type has changed"))?;
1047
1048 Ok(read(view, self))
1049 }
1050}
1051
1052/// These effects are processed at the end of each application update cycle.
1053pub(crate) enum Effect {
1054 Notify {
1055 emitter: EntityId,
1056 },
1057 Emit {
1058 emitter: EntityId,
1059 event_type: TypeId,
1060 event: Box<dyn Any>,
1061 },
1062 FocusChanged {
1063 window_handle: AnyWindowHandle,
1064 focused: Option<FocusId>,
1065 },
1066 Refresh,
1067 NotifyGlobalObservers {
1068 global_type: TypeId,
1069 },
1070 Defer {
1071 callback: Box<dyn FnOnce(&mut AppContext) + 'static>,
1072 },
1073}
1074
1075/// Wraps a global variable value during `update_global` while the value has been moved to the stack.
1076pub(crate) struct GlobalLease<G: 'static> {
1077 global: AnyBox,
1078 global_type: PhantomData<G>,
1079}
1080
1081impl<G: 'static> GlobalLease<G> {
1082 fn new(global: AnyBox) -> Self {
1083 GlobalLease {
1084 global,
1085 global_type: PhantomData,
1086 }
1087 }
1088}
1089
1090impl<G: 'static> Deref for GlobalLease<G> {
1091 type Target = G;
1092
1093 fn deref(&self) -> &Self::Target {
1094 self.global.downcast_ref().unwrap()
1095 }
1096}
1097
1098impl<G: 'static> DerefMut for GlobalLease<G> {
1099 fn deref_mut(&mut self) -> &mut Self::Target {
1100 self.global.downcast_mut().unwrap()
1101 }
1102}
1103
1104/// Contains state associated with an active drag operation, started by dragging an element
1105/// within the window or by dragging into the app from the underlying platform.
1106pub(crate) struct AnyDrag {
1107 pub view: AnyView,
1108 pub cursor_offset: Point<Pixels>,
1109}
1110
1111#[derive(Clone)]
1112pub(crate) struct AnyTooltip {
1113 pub view: AnyView,
1114 pub cursor_offset: Point<Pixels>,
1115}