app.rs

  1mod async_context;
  2mod entity_map;
  3mod model_context;
  4
  5pub use async_context::*;
  6pub use entity_map::*;
  7pub use model_context::*;
  8use refineable::Refineable;
  9use smallvec::SmallVec;
 10
 11use crate::{
 12    current_platform, image_cache::ImageCache, Action, AppMetadata, AssetSource, Context,
 13    DispatchPhase, DisplayId, Executor, FocusEvent, FocusHandle, FocusId, KeyBinding, Keymap,
 14    LayoutId, MainThread, MainThreadOnly, Platform, SharedString, SubscriberSet, Subscription,
 15    SvgRenderer, Task, TextStyle, TextStyleRefinement, TextSystem, View, Window, WindowContext,
 16    WindowHandle, WindowId,
 17};
 18use anyhow::{anyhow, Result};
 19use collections::{HashMap, HashSet, VecDeque};
 20use futures::{future::BoxFuture, Future};
 21use parking_lot::{Mutex, RwLock};
 22use slotmap::SlotMap;
 23use std::{
 24    any::{type_name, Any, TypeId},
 25    mem,
 26    sync::{atomic::Ordering::SeqCst, Arc, Weak},
 27    time::Duration,
 28};
 29use util::http::{self, HttpClient};
 30
 31pub struct App(Arc<Mutex<AppContext>>);
 32
 33impl App {
 34    pub fn production(asset_source: Arc<dyn AssetSource>) -> Self {
 35        let http_client = http::client();
 36        Self::new(current_platform(), asset_source, http_client)
 37    }
 38
 39    #[cfg(any(test, feature = "test"))]
 40    pub fn test() -> Self {
 41        let platform = Arc::new(super::TestPlatform::new());
 42        let asset_source = Arc::new(());
 43        let http_client = util::http::FakeHttpClient::with_404_response();
 44        Self::new(platform, asset_source, http_client)
 45    }
 46
 47    fn new(
 48        platform: Arc<dyn Platform>,
 49        asset_source: Arc<dyn AssetSource>,
 50        http_client: Arc<dyn HttpClient>,
 51    ) -> Self {
 52        let executor = platform.executor();
 53        assert!(
 54            executor.is_main_thread(),
 55            "must construct App on main thread"
 56        );
 57
 58        let text_system = Arc::new(TextSystem::new(platform.text_system()));
 59        let entities = EntityMap::new();
 60        let unit_entity = entities.insert(entities.reserve(), ());
 61        let app_metadata = AppMetadata {
 62            os_name: platform.os_name(),
 63            os_version: platform.os_version().ok(),
 64            app_version: platform.app_version().ok(),
 65        };
 66        Self(Arc::new_cyclic(|this| {
 67            Mutex::new(AppContext {
 68                this: this.clone(),
 69                text_system,
 70                platform: MainThreadOnly::new(platform, executor.clone()),
 71                app_metadata,
 72                flushing_effects: false,
 73                pending_updates: 0,
 74                next_frame_callbacks: Default::default(),
 75                executor,
 76                svg_renderer: SvgRenderer::new(asset_source),
 77                image_cache: ImageCache::new(http_client),
 78                text_style_stack: Vec::new(),
 79                globals_by_type: HashMap::default(),
 80                unit_entity,
 81                entities,
 82                windows: SlotMap::with_key(),
 83                keymap: Arc::new(RwLock::new(Keymap::default())),
 84                global_action_listeners: HashMap::default(),
 85                action_builders: HashMap::default(),
 86                pending_effects: VecDeque::new(),
 87                pending_notifications: HashSet::default(),
 88                pending_global_notifications: HashSet::default(),
 89                observers: SubscriberSet::new(),
 90                event_listeners: SubscriberSet::new(),
 91                release_listeners: SubscriberSet::new(),
 92                global_observers: SubscriberSet::new(),
 93                quit_observers: SubscriberSet::new(),
 94                layout_id_buffer: Default::default(),
 95                propagate_event: true,
 96            })
 97        }))
 98    }
 99
100    pub fn run<F>(self, on_finish_launching: F)
101    where
102        F: 'static + FnOnce(&mut MainThread<AppContext>),
103    {
104        let this = self.0.clone();
105        let platform = self.0.lock().platform.clone();
106        platform.borrow_on_main_thread().run(Box::new(move || {
107            let cx = &mut *this.lock();
108            let cx = unsafe { mem::transmute::<&mut AppContext, &mut MainThread<AppContext>>(cx) };
109            on_finish_launching(cx);
110        }));
111    }
112
113    pub fn on_open_urls<F>(&self, mut callback: F) -> &Self
114    where
115        F: 'static + FnMut(Vec<String>, &mut AppContext),
116    {
117        let this = Arc::downgrade(&self.0);
118        self.0
119            .lock()
120            .platform
121            .borrow_on_main_thread()
122            .on_open_urls(Box::new(move |urls| {
123                if let Some(app) = this.upgrade() {
124                    callback(urls, &mut app.lock());
125                }
126            }));
127        self
128    }
129
130    pub fn on_reopen<F>(&self, mut callback: F) -> &Self
131    where
132        F: 'static + FnMut(&mut AppContext),
133    {
134        let this = Arc::downgrade(&self.0);
135        self.0
136            .lock()
137            .platform
138            .borrow_on_main_thread()
139            .on_reopen(Box::new(move || {
140                if let Some(app) = this.upgrade() {
141                    callback(&mut app.lock());
142                }
143            }));
144        self
145    }
146
147    pub fn metadata(&self) -> AppMetadata {
148        self.0.lock().app_metadata.clone()
149    }
150
151    pub fn executor(&self) -> Executor {
152        self.0.lock().executor.clone()
153    }
154
155    pub fn text_system(&self) -> Arc<TextSystem> {
156        self.0.lock().text_system.clone()
157    }
158}
159
160type ActionBuilder = fn(json: Option<serde_json::Value>) -> anyhow::Result<Box<dyn Action>>;
161type FrameCallback = Box<dyn FnOnce(&mut WindowContext) + Send>;
162type Handler = Box<dyn Fn(&mut AppContext) -> bool + Send + Sync + 'static>;
163type Listener = Box<dyn Fn(&dyn Any, &mut AppContext) -> bool + Send + Sync + 'static>;
164type QuitHandler = Box<dyn Fn(&mut AppContext) -> BoxFuture<'static, ()> + Send + Sync + 'static>;
165type ReleaseListener = Box<dyn Fn(&mut dyn Any, &mut AppContext) + Send + Sync + 'static>;
166
167pub struct AppContext {
168    this: Weak<Mutex<AppContext>>,
169    pub(crate) platform: MainThreadOnly<dyn Platform>,
170    app_metadata: AppMetadata,
171    text_system: Arc<TextSystem>,
172    flushing_effects: bool,
173    pending_updates: usize,
174    pub(crate) next_frame_callbacks: HashMap<DisplayId, Vec<FrameCallback>>,
175    pub(crate) executor: Executor,
176    pub(crate) svg_renderer: SvgRenderer,
177    pub(crate) image_cache: ImageCache,
178    pub(crate) text_style_stack: Vec<TextStyleRefinement>,
179    pub(crate) globals_by_type: HashMap<TypeId, Box<dyn Any + Send + Sync>>,
180    pub(crate) unit_entity: Handle<()>,
181    pub(crate) entities: EntityMap,
182    pub(crate) windows: SlotMap<WindowId, Option<Window>>,
183    pub(crate) keymap: Arc<RwLock<Keymap>>,
184    pub(crate) global_action_listeners:
185        HashMap<TypeId, Vec<Box<dyn Fn(&dyn Action, DispatchPhase, &mut Self) + Send + Sync>>>,
186    action_builders: HashMap<SharedString, ActionBuilder>,
187    pending_effects: VecDeque<Effect>,
188    pub(crate) pending_notifications: HashSet<EntityId>,
189    pub(crate) pending_global_notifications: HashSet<TypeId>,
190    pub(crate) observers: SubscriberSet<EntityId, Handler>,
191    pub(crate) event_listeners: SubscriberSet<EntityId, Listener>,
192    pub(crate) release_listeners: SubscriberSet<EntityId, ReleaseListener>,
193    pub(crate) global_observers: SubscriberSet<TypeId, Listener>,
194    pub(crate) quit_observers: SubscriberSet<(), QuitHandler>,
195    pub(crate) layout_id_buffer: Vec<LayoutId>, // We recycle this memory across layout requests.
196    pub(crate) propagate_event: bool,
197}
198
199impl AppContext {
200    pub fn quit(&mut self) {
201        let mut futures = Vec::new();
202
203        self.quit_observers.clone().retain(&(), |observer| {
204            futures.push(observer(self));
205            true
206        });
207
208        self.windows.clear();
209        self.flush_effects();
210
211        let futures = futures::future::join_all(futures);
212        if self
213            .executor
214            .block_with_timeout(Duration::from_millis(100), futures)
215            .is_err()
216        {
217            log::error!("timed out waiting on app_will_quit");
218        }
219    }
220
221    pub fn app_metadata(&self) -> AppMetadata {
222        self.app_metadata.clone()
223    }
224
225    pub fn refresh(&mut self) {
226        self.pending_effects.push_back(Effect::Refresh);
227    }
228
229    pub(crate) fn update<R>(&mut self, update: impl FnOnce(&mut Self) -> R) -> R {
230        self.pending_updates += 1;
231        let result = update(self);
232        if !self.flushing_effects && self.pending_updates == 1 {
233            self.flushing_effects = true;
234            self.flush_effects();
235            self.flushing_effects = false;
236        }
237        self.pending_updates -= 1;
238        result
239    }
240
241    pub(crate) fn read_window<R>(
242        &mut self,
243        id: WindowId,
244        read: impl FnOnce(&WindowContext) -> R,
245    ) -> Result<R> {
246        let window = self
247            .windows
248            .get(id)
249            .ok_or_else(|| anyhow!("window not found"))?
250            .as_ref()
251            .unwrap();
252        Ok(read(&WindowContext::immutable(self, &window)))
253    }
254
255    pub(crate) fn update_window<R>(
256        &mut self,
257        id: WindowId,
258        update: impl FnOnce(&mut WindowContext) -> R,
259    ) -> Result<R> {
260        self.update(|cx| {
261            let mut window = cx
262                .windows
263                .get_mut(id)
264                .ok_or_else(|| anyhow!("window not found"))?
265                .take()
266                .unwrap();
267
268            let result = update(&mut WindowContext::mutable(cx, &mut window));
269
270            cx.windows
271                .get_mut(id)
272                .ok_or_else(|| anyhow!("window not found"))?
273                .replace(window);
274
275            Ok(result)
276        })
277    }
278
279    pub(crate) fn push_effect(&mut self, effect: Effect) {
280        match &effect {
281            Effect::Notify { emitter } => {
282                if !self.pending_notifications.insert(*emitter) {
283                    return;
284                }
285            }
286            Effect::NotifyGlobalObservers { global_type } => {
287                if !self.pending_global_notifications.insert(*global_type) {
288                    return;
289                }
290            }
291            _ => {}
292        };
293
294        self.pending_effects.push_back(effect);
295    }
296
297    fn flush_effects(&mut self) {
298        loop {
299            self.release_dropped_entities();
300            self.release_dropped_focus_handles();
301            if let Some(effect) = self.pending_effects.pop_front() {
302                match effect {
303                    Effect::Notify { emitter } => {
304                        self.apply_notify_effect(emitter);
305                    }
306                    Effect::Emit { emitter, event } => self.apply_emit_effect(emitter, event),
307                    Effect::FocusChanged { window_id, focused } => {
308                        self.apply_focus_changed_effect(window_id, focused);
309                    }
310                    Effect::Refresh => {
311                        self.apply_refresh_effect();
312                    }
313                    Effect::NotifyGlobalObservers { global_type } => {
314                        self.apply_notify_global_observers_effect(global_type);
315                    }
316                }
317            } else {
318                break;
319            }
320        }
321
322        let dirty_window_ids = self
323            .windows
324            .iter()
325            .filter_map(|(window_id, window)| {
326                let window = window.as_ref().unwrap();
327                if window.dirty {
328                    Some(window_id)
329                } else {
330                    None
331                }
332            })
333            .collect::<SmallVec<[_; 8]>>();
334
335        for dirty_window_id in dirty_window_ids {
336            self.update_window(dirty_window_id, |cx| cx.draw()).unwrap();
337        }
338    }
339
340    fn release_dropped_entities(&mut self) {
341        loop {
342            let dropped = self.entities.take_dropped();
343            if dropped.is_empty() {
344                break;
345            }
346
347            for (entity_id, mut entity) in dropped {
348                self.observers.remove(&entity_id);
349                self.event_listeners.remove(&entity_id);
350                for release_callback in self.release_listeners.remove(&entity_id) {
351                    release_callback(&mut entity, self);
352                }
353            }
354        }
355    }
356
357    fn release_dropped_focus_handles(&mut self) {
358        let window_ids = self.windows.keys().collect::<SmallVec<[_; 8]>>();
359        for window_id in window_ids {
360            self.update_window(window_id, |cx| {
361                let mut blur_window = false;
362                let focus = cx.window.focus;
363                cx.window.focus_handles.write().retain(|handle_id, count| {
364                    if count.load(SeqCst) == 0 {
365                        if focus == Some(handle_id) {
366                            blur_window = true;
367                        }
368                        false
369                    } else {
370                        true
371                    }
372                });
373
374                if blur_window {
375                    cx.blur();
376                }
377            })
378            .unwrap();
379        }
380    }
381
382    fn apply_notify_effect(&mut self, emitter: EntityId) {
383        self.pending_notifications.remove(&emitter);
384        self.observers
385            .clone()
386            .retain(&emitter, |handler| handler(self));
387    }
388
389    fn apply_emit_effect(&mut self, emitter: EntityId, event: Box<dyn Any>) {
390        self.event_listeners
391            .clone()
392            .retain(&emitter, |handler| handler(&event, self));
393    }
394
395    fn apply_focus_changed_effect(&mut self, window_id: WindowId, focused: Option<FocusId>) {
396        self.update_window(window_id, |cx| {
397            if cx.window.focus == focused {
398                let mut listeners = mem::take(&mut cx.window.focus_listeners);
399                let focused =
400                    focused.map(|id| FocusHandle::for_id(id, &cx.window.focus_handles).unwrap());
401                let blurred = cx
402                    .window
403                    .last_blur
404                    .take()
405                    .unwrap()
406                    .and_then(|id| FocusHandle::for_id(id, &cx.window.focus_handles));
407                if focused.is_some() || blurred.is_some() {
408                    let event = FocusEvent { focused, blurred };
409                    for listener in &listeners {
410                        listener(&event, cx);
411                    }
412                }
413
414                listeners.extend(cx.window.focus_listeners.drain(..));
415                cx.window.focus_listeners = listeners;
416            }
417        })
418        .ok();
419    }
420
421    fn apply_refresh_effect(&mut self) {
422        for window in self.windows.values_mut() {
423            if let Some(window) = window.as_mut() {
424                window.dirty = true;
425            }
426        }
427    }
428
429    fn apply_notify_global_observers_effect(&mut self, type_id: TypeId) {
430        self.pending_global_notifications.insert(type_id);
431        let global = self.globals_by_type.remove(&type_id).unwrap();
432        self.global_observers
433            .clone()
434            .retain(&type_id, |observer| observer(global.as_ref(), self));
435        self.globals_by_type.insert(type_id, global);
436    }
437
438    pub fn to_async(&self) -> AsyncAppContext {
439        AsyncAppContext {
440            app: unsafe { mem::transmute(self.this.clone()) },
441            executor: self.executor.clone(),
442        }
443    }
444
445    pub fn executor(&self) -> &Executor {
446        &self.executor
447    }
448
449    pub fn run_on_main<R>(
450        &mut self,
451        f: impl FnOnce(&mut MainThread<AppContext>) -> R + Send + 'static,
452    ) -> Task<R>
453    where
454        R: Send + 'static,
455    {
456        if self.executor.is_main_thread() {
457            Task::ready(f(unsafe {
458                mem::transmute::<&mut AppContext, &mut MainThread<AppContext>>(self)
459            }))
460        } else {
461            let this = self.this.upgrade().unwrap();
462            self.executor.run_on_main(move || {
463                let cx = &mut *this.lock();
464                cx.update(|cx| f(unsafe { mem::transmute::<&mut Self, &mut MainThread<Self>>(cx) }))
465            })
466        }
467    }
468
469    pub fn spawn_on_main<F, R>(
470        &self,
471        f: impl FnOnce(&mut MainThread<AppContext>) -> F + Send + 'static,
472    ) -> Task<R>
473    where
474        F: Future<Output = R> + 'static,
475        R: Send + 'static,
476    {
477        let this = self.this.upgrade().unwrap();
478        self.executor.spawn_on_main(move || {
479            let cx = &mut *this.lock();
480            cx.update(|cx| {
481                f(unsafe { mem::transmute::<&mut AppContext, &mut MainThread<AppContext>>(cx) })
482            })
483        })
484    }
485
486    pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut + Send + 'static) -> Task<R>
487    where
488        Fut: Future<Output = R> + Send + 'static,
489        R: Send + 'static,
490    {
491        let cx = self.to_async();
492        self.executor.spawn(async move {
493            let future = f(cx);
494            future.await
495        })
496    }
497
498    pub fn text_system(&self) -> &Arc<TextSystem> {
499        &self.text_system
500    }
501
502    pub fn text_style(&self) -> TextStyle {
503        let mut style = TextStyle::default();
504        for refinement in &self.text_style_stack {
505            style.refine(refinement);
506        }
507        style
508    }
509
510    pub fn has_global<G: 'static>(&self) -> bool {
511        self.globals_by_type.contains_key(&TypeId::of::<G>())
512    }
513
514    pub fn global<G: 'static>(&self) -> &G {
515        self.globals_by_type
516            .get(&TypeId::of::<G>())
517            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
518            .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
519            .unwrap()
520    }
521
522    pub fn try_global<G: 'static>(&self) -> Option<&G> {
523        self.globals_by_type
524            .get(&TypeId::of::<G>())
525            .map(|any_state| any_state.downcast_ref::<G>().unwrap())
526    }
527
528    pub fn global_mut<G: 'static>(&mut self) -> &mut G {
529        let global_type = TypeId::of::<G>();
530        self.push_effect(Effect::NotifyGlobalObservers { global_type });
531        self.globals_by_type
532            .get_mut(&global_type)
533            .and_then(|any_state| any_state.downcast_mut::<G>())
534            .ok_or_else(|| anyhow!("no state of type {} exists", type_name::<G>()))
535            .unwrap()
536    }
537
538    pub fn default_global_mut<G: 'static + Default + Sync + Send>(&mut self) -> &mut G {
539        let global_type = TypeId::of::<G>();
540        self.push_effect(Effect::NotifyGlobalObservers { global_type });
541        self.globals_by_type
542            .entry(global_type)
543            .or_insert_with(|| Box::new(G::default()))
544            .downcast_mut::<G>()
545            .unwrap()
546    }
547
548    pub fn set_global<T: Send + Sync + 'static>(&mut self, global: T) {
549        let global_type = TypeId::of::<T>();
550        self.push_effect(Effect::NotifyGlobalObservers { global_type });
551        self.globals_by_type.insert(global_type, Box::new(global));
552    }
553
554    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
555    where
556        G: 'static + Send + Sync,
557    {
558        let mut global = self.lease_global::<G>();
559        let result = f(global.as_mut(), self);
560        self.restore_global(global);
561        result
562    }
563
564    pub fn observe_global<G: 'static>(
565        &mut self,
566        f: impl Fn(&G, &mut Self) + Send + Sync + 'static,
567    ) -> Subscription {
568        self.global_observers.insert(
569            TypeId::of::<G>(),
570            Box::new(move |global, cx| {
571                f(global.downcast_ref::<G>().unwrap(), cx);
572                true
573            }),
574        )
575    }
576
577    pub(crate) fn lease_global<G: 'static + Send + Sync>(&mut self) -> Box<G> {
578        self.globals_by_type
579            .remove(&TypeId::of::<G>())
580            .ok_or_else(|| anyhow!("no global registered of type {}", type_name::<G>()))
581            .unwrap()
582            .downcast()
583            .unwrap()
584    }
585
586    pub(crate) fn restore_global<G: 'static + Send + Sync>(&mut self, global: Box<G>) {
587        let global_type = TypeId::of::<G>();
588        self.push_effect(Effect::NotifyGlobalObservers { global_type });
589        self.globals_by_type.insert(global_type, global);
590    }
591
592    pub(crate) fn push_text_style(&mut self, text_style: TextStyleRefinement) {
593        self.text_style_stack.push(text_style);
594    }
595
596    pub(crate) fn pop_text_style(&mut self) {
597        self.text_style_stack.pop();
598    }
599
600    pub fn bind_keys(&mut self, bindings: impl IntoIterator<Item = KeyBinding>) {
601        self.keymap.write().add_bindings(bindings);
602        self.pending_effects.push_back(Effect::Refresh);
603    }
604
605    pub fn on_action<A: Action>(
606        &mut self,
607        listener: impl Fn(&A, &mut Self) + Send + Sync + 'static,
608    ) {
609        self.global_action_listeners
610            .entry(TypeId::of::<A>())
611            .or_default()
612            .push(Box::new(move |action, phase, cx| {
613                if phase == DispatchPhase::Bubble {
614                    let action = action.as_any().downcast_ref().unwrap();
615                    listener(action, cx)
616                }
617            }));
618    }
619
620    pub fn register_action_type<A: Action>(&mut self) {
621        self.action_builders.insert(A::qualified_name(), A::build);
622    }
623
624    pub fn build_action(
625        &mut self,
626        name: &str,
627        params: Option<serde_json::Value>,
628    ) -> Result<Box<dyn Action>> {
629        let build = self
630            .action_builders
631            .get(name)
632            .ok_or_else(|| anyhow!("no action type registered for {}", name))?;
633        (build)(params)
634    }
635
636    pub fn stop_propagation(&mut self) {
637        self.propagate_event = false;
638    }
639}
640
641impl Context for AppContext {
642    type EntityContext<'a, 'w, T: Send + Sync + 'static> = ModelContext<'a, T>;
643    type Result<T> = T;
644
645    fn entity<T: Send + Sync + 'static>(
646        &mut self,
647        build_entity: impl FnOnce(&mut Self::EntityContext<'_, '_, T>) -> T,
648    ) -> Handle<T> {
649        self.update(|cx| {
650            let slot = cx.entities.reserve();
651            let entity = build_entity(&mut ModelContext::mutable(cx, slot.id));
652            cx.entities.insert(slot, entity)
653        })
654    }
655
656    fn update_entity<T: Send + Sync + 'static, R>(
657        &mut self,
658        handle: &Handle<T>,
659        update: impl FnOnce(&mut T, &mut Self::EntityContext<'_, '_, T>) -> R,
660    ) -> R {
661        self.update(|cx| {
662            let mut entity = cx.entities.lease(handle);
663            let result = update(&mut entity, &mut ModelContext::mutable(cx, handle.id));
664            cx.entities.end_lease(entity);
665            result
666        })
667    }
668}
669
670impl MainThread<AppContext> {
671    fn update<R>(&mut self, update: impl FnOnce(&mut Self) -> R) -> R {
672        self.0.update(|cx| {
673            update(unsafe {
674                std::mem::transmute::<&mut AppContext, &mut MainThread<AppContext>>(cx)
675            })
676        })
677    }
678
679    pub(crate) fn update_window<R>(
680        &mut self,
681        id: WindowId,
682        update: impl FnOnce(&mut MainThread<WindowContext>) -> R,
683    ) -> Result<R> {
684        self.0.update_window(id, |cx| {
685            update(unsafe {
686                std::mem::transmute::<&mut WindowContext, &mut MainThread<WindowContext>>(cx)
687            })
688        })
689    }
690
691    pub(crate) fn platform(&self) -> &dyn Platform {
692        self.platform.borrow_on_main_thread()
693    }
694
695    pub fn activate(&self, ignoring_other_apps: bool) {
696        self.platform().activate(ignoring_other_apps);
697    }
698
699    pub fn write_credentials(&self, url: &str, username: &str, password: &[u8]) -> Result<()> {
700        self.platform().write_credentials(url, username, password)
701    }
702
703    pub fn read_credentials(&self, url: &str) -> Result<Option<(String, Vec<u8>)>> {
704        self.platform().read_credentials(url)
705    }
706
707    pub fn delete_credentials(&self, url: &str) -> Result<()> {
708        self.platform().delete_credentials(url)
709    }
710
711    pub fn open_url(&self, url: &str) {
712        self.platform().open_url(url);
713    }
714
715    pub fn open_window<S: 'static + Send + Sync>(
716        &mut self,
717        options: crate::WindowOptions,
718        build_root_view: impl FnOnce(&mut WindowContext) -> View<S> + Send + 'static,
719    ) -> WindowHandle<S> {
720        self.update(|cx| {
721            let id = cx.windows.insert(None);
722            let handle = WindowHandle::new(id);
723            let mut window = Window::new(handle.into(), options, cx);
724            let root_view = build_root_view(&mut WindowContext::mutable(cx, &mut window));
725            window.root_view.replace(root_view.into_any());
726            cx.windows.get_mut(id).unwrap().replace(window);
727            handle
728        })
729    }
730
731    pub fn update_global<G: 'static + Send + Sync, R>(
732        &mut self,
733        update: impl FnOnce(&mut G, &mut MainThread<AppContext>) -> R,
734    ) -> R {
735        self.0.update_global(|global, cx| {
736            let cx = unsafe { mem::transmute::<&mut AppContext, &mut MainThread<AppContext>>(cx) };
737            update(global, cx)
738        })
739    }
740}
741
742pub(crate) enum Effect {
743    Notify {
744        emitter: EntityId,
745    },
746    Emit {
747        emitter: EntityId,
748        event: Box<dyn Any + Send + Sync + 'static>,
749    },
750    FocusChanged {
751        window_id: WindowId,
752        focused: Option<FocusId>,
753    },
754    Refresh,
755    NotifyGlobalObservers {
756        global_type: TypeId,
757    },
758}
759
760#[cfg(test)]
761mod tests {
762    use super::AppContext;
763
764    #[test]
765    fn test_app_context_send_sync() {
766        // This will not compile if `AppContext` does not implement `Send`
767        fn assert_send<T: Send>() {}
768        assert_send::<AppContext>();
769    }
770}