window.rs

   1use crate::{
   2    key_dispatch::DispatchActionListener, px, size, Action, AnyDrag, AnyView, AppContext,
   3    AsyncWindowContext, AvailableSpace, Bounds, BoxShadow, Context, Corners, CursorStyle,
   4    DevicePixels, DispatchNodeId, DispatchTree, DisplayId, Edges, Effect, Entity, EntityId,
   5    EventEmitter, FileDropEvent, Flatten, FontId, GlobalElementId, GlyphId, Hsla, ImageData,
   6    InputEvent, IsZero, KeyBinding, KeyContext, KeyDownEvent, KeystrokeEvent, LayoutId, Model,
   7    ModelContext, Modifiers, MonochromeSprite, MouseButton, MouseMoveEvent, MouseUpEvent, Path,
   8    Pixels, PlatformAtlas, PlatformDisplay, PlatformInputHandler, PlatformWindow, Point,
   9    PolychromeSprite, PromptLevel, Quad, Render, RenderGlyphParams, RenderImageParams,
  10    RenderSvgParams, ScaledPixels, Scene, SceneBuilder, Shadow, SharedString, Size, Style,
  11    SubscriberSet, Subscription, Surface, TaffyLayoutEngine, Task, Underline, UnderlineStyle, View,
  12    VisualContext, WeakView, WindowBounds, WindowOptions, SUBPIXEL_VARIANTS,
  13};
  14use anyhow::{anyhow, Context as _, Result};
  15use collections::HashMap;
  16use derive_more::{Deref, DerefMut};
  17use futures::{
  18    channel::{mpsc, oneshot},
  19    StreamExt,
  20};
  21use media::core_video::CVImageBuffer;
  22use parking_lot::RwLock;
  23use slotmap::SlotMap;
  24use smallvec::SmallVec;
  25use std::{
  26    any::{Any, TypeId},
  27    borrow::{Borrow, BorrowMut, Cow},
  28    fmt::Debug,
  29    future::Future,
  30    hash::{Hash, Hasher},
  31    marker::PhantomData,
  32    mem,
  33    rc::Rc,
  34    sync::{
  35        atomic::{AtomicUsize, Ordering::SeqCst},
  36        Arc,
  37    },
  38};
  39use util::ResultExt;
  40
  41const ACTIVE_DRAG_Z_INDEX: u32 = 1;
  42
  43/// A global stacking order, which is created by stacking successive z-index values.
  44/// Each z-index will always be interpreted in the context of its parent z-index.
  45#[derive(Deref, DerefMut, Ord, PartialOrd, Eq, PartialEq, Clone, Default, Debug)]
  46pub struct StackingOrder(pub(crate) SmallVec<[u32; 16]>);
  47
  48/// Represents the two different phases when dispatching events.
  49#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  50pub enum DispatchPhase {
  51    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  52    /// invoked front to back and keyboard event listeners are invoked from the focused element
  53    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  54    /// registering event listeners.
  55    #[default]
  56    Bubble,
  57    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  58    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  59    /// is used for special purposes such as clearing the "pressed" state for click events. If
  60    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  61    /// outside of the immediate region may rely on detecting non-local events during this phase.
  62    Capture,
  63}
  64
  65impl DispatchPhase {
  66    pub fn bubble(self) -> bool {
  67        self == DispatchPhase::Bubble
  68    }
  69
  70    pub fn capture(self) -> bool {
  71        self == DispatchPhase::Capture
  72    }
  73}
  74
  75type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
  76type AnyMouseListener = Box<dyn FnMut(&dyn Any, DispatchPhase, &mut WindowContext) + 'static>;
  77type AnyWindowFocusListener = Box<dyn FnMut(&FocusEvent, &mut WindowContext) -> bool + 'static>;
  78
  79struct FocusEvent {
  80    previous_focus_path: SmallVec<[FocusId; 8]>,
  81    current_focus_path: SmallVec<[FocusId; 8]>,
  82}
  83
  84slotmap::new_key_type! { pub struct FocusId; }
  85
  86impl FocusId {
  87    /// Obtains whether the element associated with this handle is currently focused.
  88    pub fn is_focused(&self, cx: &WindowContext) -> bool {
  89        cx.window.focus == Some(*self)
  90    }
  91
  92    /// Obtains whether the element associated with this handle contains the focused
  93    /// element or is itself focused.
  94    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
  95        cx.focused()
  96            .map_or(false, |focused| self.contains(focused.id, cx))
  97    }
  98
  99    /// Obtains whether the element associated with this handle is contained within the
 100    /// focused element or is itself focused.
 101    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 102        let focused = cx.focused();
 103        focused.map_or(false, |focused| focused.id.contains(*self, cx))
 104    }
 105
 106    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 107    pub(crate) fn contains(&self, other: Self, cx: &WindowContext) -> bool {
 108        cx.window
 109            .rendered_frame
 110            .dispatch_tree
 111            .focus_contains(*self, other)
 112    }
 113}
 114
 115/// A handle which can be used to track and manipulate the focused element in a window.
 116pub struct FocusHandle {
 117    pub(crate) id: FocusId,
 118    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 119}
 120
 121impl std::fmt::Debug for FocusHandle {
 122    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 123        f.write_fmt(format_args!("FocusHandle({:?})", self.id))
 124    }
 125}
 126
 127impl FocusHandle {
 128    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
 129        let id = handles.write().insert(AtomicUsize::new(1));
 130        Self {
 131            id,
 132            handles: handles.clone(),
 133        }
 134    }
 135
 136    pub(crate) fn for_id(
 137        id: FocusId,
 138        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 139    ) -> Option<Self> {
 140        let lock = handles.read();
 141        let ref_count = lock.get(id)?;
 142        if ref_count.load(SeqCst) == 0 {
 143            None
 144        } else {
 145            ref_count.fetch_add(1, SeqCst);
 146            Some(Self {
 147                id,
 148                handles: handles.clone(),
 149            })
 150        }
 151    }
 152
 153    /// Moves the focus to the element associated with this handle.
 154    pub fn focus(&self, cx: &mut WindowContext) {
 155        cx.focus(self)
 156    }
 157
 158    /// Obtains whether the element associated with this handle is currently focused.
 159    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 160        self.id.is_focused(cx)
 161    }
 162
 163    /// Obtains whether the element associated with this handle contains the focused
 164    /// element or is itself focused.
 165    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 166        self.id.contains_focused(cx)
 167    }
 168
 169    /// Obtains whether the element associated with this handle is contained within the
 170    /// focused element or is itself focused.
 171    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 172        self.id.within_focused(cx)
 173    }
 174
 175    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 176    pub fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 177        self.id.contains(other.id, cx)
 178    }
 179}
 180
 181impl Clone for FocusHandle {
 182    fn clone(&self) -> Self {
 183        Self::for_id(self.id, &self.handles).unwrap()
 184    }
 185}
 186
 187impl PartialEq for FocusHandle {
 188    fn eq(&self, other: &Self) -> bool {
 189        self.id == other.id
 190    }
 191}
 192
 193impl Eq for FocusHandle {}
 194
 195impl Drop for FocusHandle {
 196    fn drop(&mut self) {
 197        self.handles
 198            .read()
 199            .get(self.id)
 200            .unwrap()
 201            .fetch_sub(1, SeqCst);
 202    }
 203}
 204
 205/// FocusableView allows users of your view to easily
 206/// focus it (using cx.focus_view(view))
 207pub trait FocusableView: 'static + Render {
 208    fn focus_handle(&self, cx: &AppContext) -> FocusHandle;
 209}
 210
 211/// ManagedView is a view (like a Modal, Popover, Menu, etc.)
 212/// where the lifecycle of the view is handled by another view.
 213pub trait ManagedView: FocusableView + EventEmitter<DismissEvent> {}
 214
 215impl<M: FocusableView + EventEmitter<DismissEvent>> ManagedView for M {}
 216
 217pub struct DismissEvent;
 218
 219// Holds the state for a specific window.
 220pub struct Window {
 221    pub(crate) handle: AnyWindowHandle,
 222    pub(crate) removed: bool,
 223    pub(crate) platform_window: Box<dyn PlatformWindow>,
 224    display_id: DisplayId,
 225    sprite_atlas: Arc<dyn PlatformAtlas>,
 226    rem_size: Pixels,
 227    viewport_size: Size<Pixels>,
 228    layout_engine: Option<TaffyLayoutEngine>,
 229    pub(crate) root_view: Option<AnyView>,
 230    pub(crate) element_id_stack: GlobalElementId,
 231    pub(crate) rendered_frame: Frame,
 232    pub(crate) next_frame: Frame,
 233    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 234    focus_listeners: SubscriberSet<(), AnyWindowFocusListener>,
 235    blur_listeners: SubscriberSet<(), AnyObserver>,
 236    default_prevented: bool,
 237    mouse_position: Point<Pixels>,
 238    requested_cursor_style: Option<CursorStyle>,
 239    scale_factor: f32,
 240    bounds: WindowBounds,
 241    bounds_observers: SubscriberSet<(), AnyObserver>,
 242    active: bool,
 243    pub(crate) dirty: bool,
 244    activation_observers: SubscriberSet<(), AnyObserver>,
 245    pub(crate) focus: Option<FocusId>,
 246}
 247
 248pub(crate) struct ElementStateBox {
 249    inner: Box<dyn Any>,
 250    #[cfg(debug_assertions)]
 251    type_name: &'static str,
 252}
 253
 254// #[derive(Default)]
 255pub(crate) struct Frame {
 256    focus: Option<FocusId>,
 257    pub(crate) element_states: HashMap<GlobalElementId, ElementStateBox>,
 258    mouse_listeners: HashMap<TypeId, Vec<(StackingOrder, AnyMouseListener)>>,
 259    pub(crate) dispatch_tree: DispatchTree,
 260    pub(crate) scene_builder: SceneBuilder,
 261    pub(crate) depth_map: Vec<(StackingOrder, Bounds<Pixels>)>,
 262    pub(crate) z_index_stack: StackingOrder,
 263    content_mask_stack: Vec<ContentMask<Pixels>>,
 264    element_offset_stack: Vec<Point<Pixels>>,
 265}
 266
 267impl Frame {
 268    fn new(dispatch_tree: DispatchTree) -> Self {
 269        Frame {
 270            focus: None,
 271            element_states: HashMap::default(),
 272            mouse_listeners: HashMap::default(),
 273            dispatch_tree,
 274            scene_builder: SceneBuilder::default(),
 275            z_index_stack: StackingOrder::default(),
 276            depth_map: Default::default(),
 277            content_mask_stack: Vec::new(),
 278            element_offset_stack: Vec::new(),
 279        }
 280    }
 281
 282    fn clear(&mut self) {
 283        self.element_states.clear();
 284        self.mouse_listeners.values_mut().for_each(Vec::clear);
 285        self.dispatch_tree.clear();
 286        self.depth_map.clear();
 287    }
 288
 289    fn focus_path(&self) -> SmallVec<[FocusId; 8]> {
 290        self.focus
 291            .map(|focus_id| self.dispatch_tree.focus_path(focus_id))
 292            .unwrap_or_default()
 293    }
 294}
 295
 296impl Window {
 297    pub(crate) fn new(
 298        handle: AnyWindowHandle,
 299        options: WindowOptions,
 300        cx: &mut AppContext,
 301    ) -> Self {
 302        let platform_window = cx.platform.open_window(
 303            handle,
 304            options,
 305            Box::new({
 306                let mut cx = cx.to_async();
 307                move || handle.update(&mut cx, |_, cx| cx.draw())
 308            }),
 309        );
 310        let display_id = platform_window.display().id();
 311        let sprite_atlas = platform_window.sprite_atlas();
 312        let mouse_position = platform_window.mouse_position();
 313        let content_size = platform_window.content_size();
 314        let scale_factor = platform_window.scale_factor();
 315        let bounds = platform_window.bounds();
 316
 317        platform_window.on_resize(Box::new({
 318            let mut cx = cx.to_async();
 319            move |_, _| {
 320                handle
 321                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 322                    .log_err();
 323            }
 324        }));
 325        platform_window.on_moved(Box::new({
 326            let mut cx = cx.to_async();
 327            move || {
 328                handle
 329                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 330                    .log_err();
 331            }
 332        }));
 333        platform_window.on_active_status_change(Box::new({
 334            let mut cx = cx.to_async();
 335            move |active| {
 336                handle
 337                    .update(&mut cx, |_, cx| {
 338                        cx.window.active = active;
 339                        cx.window
 340                            .activation_observers
 341                            .clone()
 342                            .retain(&(), |callback| callback(cx));
 343                    })
 344                    .log_err();
 345            }
 346        }));
 347
 348        platform_window.on_input({
 349            let mut cx = cx.to_async();
 350            Box::new(move |event| {
 351                handle
 352                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 353                    .log_err()
 354                    .unwrap_or(false)
 355            })
 356        });
 357
 358        Window {
 359            handle,
 360            removed: false,
 361            platform_window,
 362            display_id,
 363            sprite_atlas,
 364            rem_size: px(16.),
 365            viewport_size: content_size,
 366            layout_engine: Some(TaffyLayoutEngine::new()),
 367            root_view: None,
 368            element_id_stack: GlobalElementId::default(),
 369            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 370            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 371            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 372            focus_listeners: SubscriberSet::new(),
 373            blur_listeners: SubscriberSet::new(),
 374            default_prevented: true,
 375            mouse_position,
 376            requested_cursor_style: None,
 377            scale_factor,
 378            bounds,
 379            bounds_observers: SubscriberSet::new(),
 380            active: false,
 381            dirty: false,
 382            activation_observers: SubscriberSet::new(),
 383            focus: None,
 384        }
 385    }
 386}
 387
 388/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 389/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 390/// to leave room to support more complex shapes in the future.
 391#[derive(Clone, Debug, Default, PartialEq, Eq)]
 392#[repr(C)]
 393pub struct ContentMask<P: Clone + Default + Debug> {
 394    pub bounds: Bounds<P>,
 395}
 396
 397impl ContentMask<Pixels> {
 398    /// Scale the content mask's pixel units by the given scaling factor.
 399    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 400        ContentMask {
 401            bounds: self.bounds.scale(factor),
 402        }
 403    }
 404
 405    /// Intersect the content mask with the given content mask.
 406    pub fn intersect(&self, other: &Self) -> Self {
 407        let bounds = self.bounds.intersect(&other.bounds);
 408        ContentMask { bounds }
 409    }
 410}
 411
 412/// Provides access to application state in the context of a single window. Derefs
 413/// to an `AppContext`, so you can also pass a `WindowContext` to any method that takes
 414/// an `AppContext` and call any `AppContext` methods.
 415pub struct WindowContext<'a> {
 416    pub(crate) app: &'a mut AppContext,
 417    pub(crate) window: &'a mut Window,
 418}
 419
 420impl<'a> WindowContext<'a> {
 421    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 422        Self { app, window }
 423    }
 424
 425    /// Obtain a handle to the window that belongs to this context.
 426    pub fn window_handle(&self) -> AnyWindowHandle {
 427        self.window.handle
 428    }
 429
 430    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 431    pub fn notify(&mut self) {
 432        self.window.dirty = true;
 433    }
 434
 435    /// Close this window.
 436    pub fn remove_window(&mut self) {
 437        self.window.removed = true;
 438    }
 439
 440    /// Obtain a new `FocusHandle`, which allows you to track and manipulate the keyboard focus
 441    /// for elements rendered within this window.
 442    pub fn focus_handle(&mut self) -> FocusHandle {
 443        FocusHandle::new(&self.window.focus_handles)
 444    }
 445
 446    /// Obtain the currently focused `FocusHandle`. If no elements are focused, returns `None`.
 447    pub fn focused(&self) -> Option<FocusHandle> {
 448        self.window
 449            .focus
 450            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 451    }
 452
 453    /// Move focus to the element associated with the given `FocusHandle`.
 454    pub fn focus(&mut self, handle: &FocusHandle) {
 455        if self.window.focus == Some(handle.id) {
 456            return;
 457        }
 458
 459        self.window.focus = Some(handle.id);
 460        self.window
 461            .rendered_frame
 462            .dispatch_tree
 463            .clear_pending_keystrokes();
 464        self.notify();
 465    }
 466
 467    /// Remove focus from all elements within this context's window.
 468    pub fn blur(&mut self) {
 469        self.window.focus = None;
 470        self.notify();
 471    }
 472
 473    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 474        let focus_handle = self.focused();
 475
 476        self.defer(move |cx| {
 477            let node_id = focus_handle
 478                .and_then(|handle| {
 479                    cx.window
 480                        .rendered_frame
 481                        .dispatch_tree
 482                        .focusable_node_id(handle.id)
 483                })
 484                .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 485
 486            cx.propagate_event = true;
 487            cx.dispatch_action_on_node(node_id, action);
 488        })
 489    }
 490
 491    pub(crate) fn dispatch_keystroke_observers(
 492        &mut self,
 493        event: &dyn Any,
 494        action: Option<Box<dyn Action>>,
 495    ) {
 496        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 497            return;
 498        };
 499
 500        self.keystroke_observers
 501            .clone()
 502            .retain(&(), move |callback| {
 503                (callback)(
 504                    &KeystrokeEvent {
 505                        keystroke: key_down_event.keystroke.clone(),
 506                        action: action.as_ref().map(|action| action.boxed_clone()),
 507                    },
 508                    self,
 509                );
 510                true
 511            });
 512    }
 513
 514    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 515    /// that are currently on the stack to be returned to the app.
 516    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 517        let handle = self.window.handle;
 518        self.app.defer(move |cx| {
 519            handle.update(cx, |_, cx| f(cx)).ok();
 520        });
 521    }
 522
 523    pub fn subscribe<Emitter, E, Evt>(
 524        &mut self,
 525        entity: &E,
 526        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 527    ) -> Subscription
 528    where
 529        Emitter: EventEmitter<Evt>,
 530        E: Entity<Emitter>,
 531        Evt: 'static,
 532    {
 533        let entity_id = entity.entity_id();
 534        let entity = entity.downgrade();
 535        let window_handle = self.window.handle;
 536        let (subscription, activate) = self.app.event_listeners.insert(
 537            entity_id,
 538            (
 539                TypeId::of::<Evt>(),
 540                Box::new(move |event, cx| {
 541                    window_handle
 542                        .update(cx, |_, cx| {
 543                            if let Some(handle) = E::upgrade_from(&entity) {
 544                                let event = event.downcast_ref().expect("invalid event type");
 545                                on_event(handle, event, cx);
 546                                true
 547                            } else {
 548                                false
 549                            }
 550                        })
 551                        .unwrap_or(false)
 552                }),
 553            ),
 554        );
 555        self.app.defer(move |_| activate());
 556        subscription
 557    }
 558
 559    /// Create an `AsyncWindowContext`, which has a static lifetime and can be held across
 560    /// await points in async code.
 561    pub fn to_async(&self) -> AsyncWindowContext {
 562        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 563    }
 564
 565    /// Schedule the given closure to be run directly after the current frame is rendered.
 566    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 567        let handle = self.window.handle;
 568        let display_id = self.window.display_id;
 569
 570        if !self.frame_consumers.contains_key(&display_id) {
 571            let (tx, mut rx) = mpsc::unbounded::<()>();
 572            self.platform.set_display_link_output_callback(
 573                display_id,
 574                Box::new(move |_current_time, _output_time| _ = tx.unbounded_send(())),
 575            );
 576
 577            let consumer_task = self.app.spawn(|cx| async move {
 578                while rx.next().await.is_some() {
 579                    cx.update(|cx| {
 580                        for callback in cx
 581                            .next_frame_callbacks
 582                            .get_mut(&display_id)
 583                            .unwrap()
 584                            .drain(..)
 585                            .collect::<SmallVec<[_; 32]>>()
 586                        {
 587                            callback(cx);
 588                        }
 589                    })
 590                    .ok();
 591
 592                    // Flush effects, then stop the display link if no new next_frame_callbacks have been added.
 593
 594                    cx.update(|cx| {
 595                        if cx.next_frame_callbacks.is_empty() {
 596                            cx.platform.stop_display_link(display_id);
 597                        }
 598                    })
 599                    .ok();
 600                }
 601            });
 602            self.frame_consumers.insert(display_id, consumer_task);
 603        }
 604
 605        if self.next_frame_callbacks.is_empty() {
 606            self.platform.start_display_link(display_id);
 607        }
 608
 609        self.next_frame_callbacks
 610            .entry(display_id)
 611            .or_default()
 612            .push(Box::new(move |cx: &mut AppContext| {
 613                cx.update_window(handle, |_root_view, cx| callback(cx)).ok();
 614            }));
 615    }
 616
 617    /// Spawn the future returned by the given closure on the application thread pool.
 618    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 619    /// use within your future.
 620    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 621    where
 622        R: 'static,
 623        Fut: Future<Output = R> + 'static,
 624    {
 625        self.app
 626            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 627    }
 628
 629    /// Update the global of the given type. The given closure is given simultaneous mutable
 630    /// access both to the global and the context.
 631    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 632    where
 633        G: 'static,
 634    {
 635        let mut global = self.app.lease_global::<G>();
 636        let result = f(&mut global, self);
 637        self.app.end_global_lease(global);
 638        result
 639    }
 640
 641    #[must_use]
 642    /// Add a node to the layout tree for the current frame. Takes the `Style` of the element for which
 643    /// layout is being requested, along with the layout ids of any children. This method is called during
 644    /// calls to the `Element::layout` trait method and enables any element to participate in layout.
 645    pub fn request_layout(
 646        &mut self,
 647        style: &Style,
 648        children: impl IntoIterator<Item = LayoutId>,
 649    ) -> LayoutId {
 650        self.app.layout_id_buffer.clear();
 651        self.app.layout_id_buffer.extend(children.into_iter());
 652        let rem_size = self.rem_size();
 653
 654        self.window.layout_engine.as_mut().unwrap().request_layout(
 655            style,
 656            rem_size,
 657            &self.app.layout_id_buffer,
 658        )
 659    }
 660
 661    /// Add a node to the layout tree for the current frame. Instead of taking a `Style` and children,
 662    /// this variant takes a function that is invoked during layout so you can use arbitrary logic to
 663    /// determine the element's size. One place this is used internally is when measuring text.
 664    ///
 665    /// The given closure is invoked at layout time with the known dimensions and available space and
 666    /// returns a `Size`.
 667    pub fn request_measured_layout<
 668        F: FnMut(Size<Option<Pixels>>, Size<AvailableSpace>, &mut WindowContext) -> Size<Pixels>
 669            + 'static,
 670    >(
 671        &mut self,
 672        style: Style,
 673        measure: F,
 674    ) -> LayoutId {
 675        let rem_size = self.rem_size();
 676        self.window
 677            .layout_engine
 678            .as_mut()
 679            .unwrap()
 680            .request_measured_layout(style, rem_size, measure)
 681    }
 682
 683    pub fn compute_layout(&mut self, layout_id: LayoutId, available_space: Size<AvailableSpace>) {
 684        let mut layout_engine = self.window.layout_engine.take().unwrap();
 685        layout_engine.compute_layout(layout_id, available_space, self);
 686        self.window.layout_engine = Some(layout_engine);
 687    }
 688
 689    /// Obtain the bounds computed for the given LayoutId relative to the window. This method should not
 690    /// be invoked until the paint phase begins, and will usually be invoked by GPUI itself automatically
 691    /// in order to pass your element its `Bounds` automatically.
 692    pub fn layout_bounds(&mut self, layout_id: LayoutId) -> Bounds<Pixels> {
 693        let mut bounds = self
 694            .window
 695            .layout_engine
 696            .as_mut()
 697            .unwrap()
 698            .layout_bounds(layout_id)
 699            .map(Into::into);
 700        bounds.origin += self.element_offset();
 701        bounds
 702    }
 703
 704    fn window_bounds_changed(&mut self) {
 705        self.window.scale_factor = self.window.platform_window.scale_factor();
 706        self.window.viewport_size = self.window.platform_window.content_size();
 707        self.window.bounds = self.window.platform_window.bounds();
 708        self.window.display_id = self.window.platform_window.display().id();
 709        self.notify();
 710
 711        self.window
 712            .bounds_observers
 713            .clone()
 714            .retain(&(), |callback| callback(self));
 715    }
 716
 717    pub fn window_bounds(&self) -> WindowBounds {
 718        self.window.bounds
 719    }
 720
 721    pub fn viewport_size(&self) -> Size<Pixels> {
 722        self.window.viewport_size
 723    }
 724
 725    pub fn is_window_active(&self) -> bool {
 726        self.window.active
 727    }
 728
 729    pub fn zoom_window(&self) {
 730        self.window.platform_window.zoom();
 731    }
 732
 733    pub fn set_window_title(&mut self, title: &str) {
 734        self.window.platform_window.set_title(title);
 735    }
 736
 737    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 738        self.platform
 739            .displays()
 740            .into_iter()
 741            .find(|display| display.id() == self.window.display_id)
 742    }
 743
 744    pub fn show_character_palette(&self) {
 745        self.window.platform_window.show_character_palette();
 746    }
 747
 748    /// The scale factor of the display associated with the window. For example, it could
 749    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 750    /// be rendered as two pixels on screen.
 751    pub fn scale_factor(&self) -> f32 {
 752        self.window.scale_factor
 753    }
 754
 755    /// The size of an em for the base font of the application. Adjusting this value allows the
 756    /// UI to scale, just like zooming a web page.
 757    pub fn rem_size(&self) -> Pixels {
 758        self.window.rem_size
 759    }
 760
 761    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 762    /// UI to scale, just like zooming a web page.
 763    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 764        self.window.rem_size = rem_size.into();
 765    }
 766
 767    /// The line height associated with the current text style.
 768    pub fn line_height(&self) -> Pixels {
 769        let rem_size = self.rem_size();
 770        let text_style = self.text_style();
 771        text_style
 772            .line_height
 773            .to_pixels(text_style.font_size.into(), rem_size)
 774    }
 775
 776    /// Call to prevent the default action of an event. Currently only used to prevent
 777    /// parent elements from becoming focused on mouse down.
 778    pub fn prevent_default(&mut self) {
 779        self.window.default_prevented = true;
 780    }
 781
 782    /// Obtain whether default has been prevented for the event currently being dispatched.
 783    pub fn default_prevented(&self) -> bool {
 784        self.window.default_prevented
 785    }
 786
 787    /// Register a mouse event listener on the window for the next frame. The type of event
 788    /// is determined by the first parameter of the given listener. When the next frame is rendered
 789    /// the listener will be cleared.
 790    ///
 791    /// This is a fairly low-level method, so prefer using event handlers on elements unless you have
 792    /// a specific need to register a global listener.
 793    pub fn on_mouse_event<Event: 'static>(
 794        &mut self,
 795        handler: impl Fn(&Event, DispatchPhase, &mut WindowContext) + 'static,
 796    ) {
 797        let order = self.window.next_frame.z_index_stack.clone();
 798        self.window
 799            .next_frame
 800            .mouse_listeners
 801            .entry(TypeId::of::<Event>())
 802            .or_default()
 803            .push((
 804                order,
 805                Box::new(move |event: &dyn Any, phase, cx| {
 806                    handler(event.downcast_ref().unwrap(), phase, cx)
 807                }),
 808            ))
 809    }
 810
 811    /// Register a key event listener on the window for the next frame. The type of event
 812    /// is determined by the first parameter of the given listener. When the next frame is rendered
 813    /// the listener will be cleared.
 814    ///
 815    /// This is a fairly low-level method, so prefer using event handlers on elements unless you have
 816    /// a specific need to register a global listener.
 817    pub fn on_key_event<Event: 'static>(
 818        &mut self,
 819        handler: impl Fn(&Event, DispatchPhase, &mut WindowContext) + 'static,
 820    ) {
 821        self.window
 822            .next_frame
 823            .dispatch_tree
 824            .on_key_event(Rc::new(move |event, phase, cx| {
 825                if let Some(event) = event.downcast_ref::<Event>() {
 826                    handler(event, phase, cx)
 827                }
 828            }));
 829    }
 830
 831    /// Register an action listener on the window for the next frame. The type of action
 832    /// is determined by the first parameter of the given listener. When the next frame is rendered
 833    /// the listener will be cleared.
 834    ///
 835    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
 836    /// a specific need to register a global listener.
 837    pub fn on_action(
 838        &mut self,
 839        action_type: TypeId,
 840        handler: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
 841    ) {
 842        self.window.next_frame.dispatch_tree.on_action(
 843            action_type,
 844            Rc::new(move |action, phase, cx| handler(action, phase, cx)),
 845        );
 846    }
 847
 848    pub fn is_action_available(&self, action: &dyn Action) -> bool {
 849        let target = self
 850            .focused()
 851            .and_then(|focused_handle| {
 852                self.window
 853                    .rendered_frame
 854                    .dispatch_tree
 855                    .focusable_node_id(focused_handle.id)
 856            })
 857            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
 858        self.window
 859            .rendered_frame
 860            .dispatch_tree
 861            .is_action_available(action, target)
 862    }
 863
 864    /// The position of the mouse relative to the window.
 865    pub fn mouse_position(&self) -> Point<Pixels> {
 866        self.window.mouse_position
 867    }
 868
 869    pub fn set_cursor_style(&mut self, style: CursorStyle) {
 870        self.window.requested_cursor_style = Some(style)
 871    }
 872
 873    /// Called during painting to invoke the given closure in a new stacking context. The given
 874    /// z-index is interpreted relative to the previous call to `stack`.
 875    pub fn with_z_index<R>(&mut self, z_index: u32, f: impl FnOnce(&mut Self) -> R) -> R {
 876        self.window.next_frame.z_index_stack.push(z_index);
 877        let result = f(self);
 878        self.window.next_frame.z_index_stack.pop();
 879        result
 880    }
 881
 882    /// Called during painting to track which z-index is on top at each pixel position
 883    pub fn add_opaque_layer(&mut self, bounds: Bounds<Pixels>) {
 884        let stacking_order = self.window.next_frame.z_index_stack.clone();
 885        let depth_map = &mut self.window.next_frame.depth_map;
 886        match depth_map.binary_search_by(|(level, _)| stacking_order.cmp(&level)) {
 887            Ok(i) | Err(i) => depth_map.insert(i, (stacking_order, bounds)),
 888        }
 889    }
 890
 891    /// Returns true if the top-most opaque layer painted over this point was part of the
 892    /// same layer as the given stacking order.
 893    pub fn was_top_layer(&self, point: &Point<Pixels>, level: &StackingOrder) -> bool {
 894        for (stack, bounds) in self.window.rendered_frame.depth_map.iter() {
 895            if bounds.contains(point) {
 896                return level.starts_with(stack) || stack.starts_with(level);
 897            }
 898        }
 899
 900        false
 901    }
 902
 903    pub fn was_top_layer_under_active_drag(
 904        &self,
 905        point: &Point<Pixels>,
 906        level: &StackingOrder,
 907    ) -> bool {
 908        for (stack, bounds) in self.window.rendered_frame.depth_map.iter() {
 909            if stack.starts_with(&[ACTIVE_DRAG_Z_INDEX]) {
 910                continue;
 911            }
 912            if bounds.contains(point) {
 913                return level.starts_with(stack) || stack.starts_with(level);
 914            }
 915        }
 916
 917        false
 918    }
 919
 920    /// Called during painting to get the current stacking order.
 921    pub fn stacking_order(&self) -> &StackingOrder {
 922        &self.window.next_frame.z_index_stack
 923    }
 924
 925    /// Paint one or more drop shadows into the scene for the next frame at the current z-index.
 926    pub fn paint_shadows(
 927        &mut self,
 928        bounds: Bounds<Pixels>,
 929        corner_radii: Corners<Pixels>,
 930        shadows: &[BoxShadow],
 931    ) {
 932        let scale_factor = self.scale_factor();
 933        let content_mask = self.content_mask();
 934        let window = &mut *self.window;
 935        for shadow in shadows {
 936            let mut shadow_bounds = bounds;
 937            shadow_bounds.origin += shadow.offset;
 938            shadow_bounds.dilate(shadow.spread_radius);
 939            window.next_frame.scene_builder.insert(
 940                &window.next_frame.z_index_stack,
 941                Shadow {
 942                    order: 0,
 943                    bounds: shadow_bounds.scale(scale_factor),
 944                    content_mask: content_mask.scale(scale_factor),
 945                    corner_radii: corner_radii.scale(scale_factor),
 946                    color: shadow.color,
 947                    blur_radius: shadow.blur_radius.scale(scale_factor),
 948                },
 949            );
 950        }
 951    }
 952
 953    /// Paint one or more quads into the scene for the next frame at the current stacking context.
 954    /// Quads are colored rectangular regions with an optional background, border, and corner radius.
 955    pub fn paint_quad(
 956        &mut self,
 957        bounds: Bounds<Pixels>,
 958        corner_radii: Corners<Pixels>,
 959        background: impl Into<Hsla>,
 960        border_widths: Edges<Pixels>,
 961        border_color: impl Into<Hsla>,
 962    ) {
 963        let scale_factor = self.scale_factor();
 964        let content_mask = self.content_mask();
 965
 966        let window = &mut *self.window;
 967        window.next_frame.scene_builder.insert(
 968            &window.next_frame.z_index_stack,
 969            Quad {
 970                order: 0,
 971                bounds: bounds.scale(scale_factor),
 972                content_mask: content_mask.scale(scale_factor),
 973                background: background.into(),
 974                border_color: border_color.into(),
 975                corner_radii: corner_radii.scale(scale_factor),
 976                border_widths: border_widths.scale(scale_factor),
 977            },
 978        );
 979    }
 980
 981    /// Paint the given `Path` into the scene for the next frame at the current z-index.
 982    pub fn paint_path(&mut self, mut path: Path<Pixels>, color: impl Into<Hsla>) {
 983        let scale_factor = self.scale_factor();
 984        let content_mask = self.content_mask();
 985        path.content_mask = content_mask;
 986        path.color = color.into();
 987        let window = &mut *self.window;
 988        window
 989            .next_frame
 990            .scene_builder
 991            .insert(&window.next_frame.z_index_stack, path.scale(scale_factor));
 992    }
 993
 994    /// Paint an underline into the scene for the next frame at the current z-index.
 995    pub fn paint_underline(
 996        &mut self,
 997        origin: Point<Pixels>,
 998        width: Pixels,
 999        style: &UnderlineStyle,
1000    ) {
1001        let scale_factor = self.scale_factor();
1002        let height = if style.wavy {
1003            style.thickness * 3.
1004        } else {
1005            style.thickness
1006        };
1007        let bounds = Bounds {
1008            origin,
1009            size: size(width, height),
1010        };
1011        let content_mask = self.content_mask();
1012        let window = &mut *self.window;
1013        window.next_frame.scene_builder.insert(
1014            &window.next_frame.z_index_stack,
1015            Underline {
1016                order: 0,
1017                bounds: bounds.scale(scale_factor),
1018                content_mask: content_mask.scale(scale_factor),
1019                thickness: style.thickness.scale(scale_factor),
1020                color: style.color.unwrap_or_default(),
1021                wavy: style.wavy,
1022            },
1023        );
1024    }
1025
1026    /// Paint a monochrome (non-emoji) glyph into the scene for the next frame at the current z-index.
1027    /// The y component of the origin is the baseline of the glyph.
1028    pub fn paint_glyph(
1029        &mut self,
1030        origin: Point<Pixels>,
1031        font_id: FontId,
1032        glyph_id: GlyphId,
1033        font_size: Pixels,
1034        color: Hsla,
1035    ) -> Result<()> {
1036        let scale_factor = self.scale_factor();
1037        let glyph_origin = origin.scale(scale_factor);
1038        let subpixel_variant = Point {
1039            x: (glyph_origin.x.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
1040            y: (glyph_origin.y.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
1041        };
1042        let params = RenderGlyphParams {
1043            font_id,
1044            glyph_id,
1045            font_size,
1046            subpixel_variant,
1047            scale_factor,
1048            is_emoji: false,
1049        };
1050
1051        let raster_bounds = self.text_system().raster_bounds(&params)?;
1052        if !raster_bounds.is_zero() {
1053            let tile =
1054                self.window
1055                    .sprite_atlas
1056                    .get_or_insert_with(&params.clone().into(), &mut || {
1057                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
1058                        Ok((size, Cow::Owned(bytes)))
1059                    })?;
1060            let bounds = Bounds {
1061                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
1062                size: tile.bounds.size.map(Into::into),
1063            };
1064            let content_mask = self.content_mask().scale(scale_factor);
1065            let window = &mut *self.window;
1066            window.next_frame.scene_builder.insert(
1067                &window.next_frame.z_index_stack,
1068                MonochromeSprite {
1069                    order: 0,
1070                    bounds,
1071                    content_mask,
1072                    color,
1073                    tile,
1074                },
1075            );
1076        }
1077        Ok(())
1078    }
1079
1080    /// Paint an emoji glyph into the scene for the next frame at the current z-index.
1081    /// The y component of the origin is the baseline of the glyph.
1082    pub fn paint_emoji(
1083        &mut self,
1084        origin: Point<Pixels>,
1085        font_id: FontId,
1086        glyph_id: GlyphId,
1087        font_size: Pixels,
1088    ) -> Result<()> {
1089        let scale_factor = self.scale_factor();
1090        let glyph_origin = origin.scale(scale_factor);
1091        let params = RenderGlyphParams {
1092            font_id,
1093            glyph_id,
1094            font_size,
1095            // We don't render emojis with subpixel variants.
1096            subpixel_variant: Default::default(),
1097            scale_factor,
1098            is_emoji: true,
1099        };
1100
1101        let raster_bounds = self.text_system().raster_bounds(&params)?;
1102        if !raster_bounds.is_zero() {
1103            let tile =
1104                self.window
1105                    .sprite_atlas
1106                    .get_or_insert_with(&params.clone().into(), &mut || {
1107                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
1108                        Ok((size, Cow::Owned(bytes)))
1109                    })?;
1110            let bounds = Bounds {
1111                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
1112                size: tile.bounds.size.map(Into::into),
1113            };
1114            let content_mask = self.content_mask().scale(scale_factor);
1115            let window = &mut *self.window;
1116
1117            window.next_frame.scene_builder.insert(
1118                &window.next_frame.z_index_stack,
1119                PolychromeSprite {
1120                    order: 0,
1121                    bounds,
1122                    corner_radii: Default::default(),
1123                    content_mask,
1124                    tile,
1125                    grayscale: false,
1126                },
1127            );
1128        }
1129        Ok(())
1130    }
1131
1132    /// Paint a monochrome SVG into the scene for the next frame at the current stacking context.
1133    pub fn paint_svg(
1134        &mut self,
1135        bounds: Bounds<Pixels>,
1136        path: SharedString,
1137        color: Hsla,
1138    ) -> Result<()> {
1139        let scale_factor = self.scale_factor();
1140        let bounds = bounds.scale(scale_factor);
1141        // Render the SVG at twice the size to get a higher quality result.
1142        let params = RenderSvgParams {
1143            path,
1144            size: bounds
1145                .size
1146                .map(|pixels| DevicePixels::from((pixels.0 * 2.).ceil() as i32)),
1147        };
1148
1149        let tile =
1150            self.window
1151                .sprite_atlas
1152                .get_or_insert_with(&params.clone().into(), &mut || {
1153                    let bytes = self.svg_renderer.render(&params)?;
1154                    Ok((params.size, Cow::Owned(bytes)))
1155                })?;
1156        let content_mask = self.content_mask().scale(scale_factor);
1157
1158        let window = &mut *self.window;
1159        window.next_frame.scene_builder.insert(
1160            &window.next_frame.z_index_stack,
1161            MonochromeSprite {
1162                order: 0,
1163                bounds,
1164                content_mask,
1165                color,
1166                tile,
1167            },
1168        );
1169
1170        Ok(())
1171    }
1172
1173    /// Paint an image into the scene for the next frame at the current z-index.
1174    pub fn paint_image(
1175        &mut self,
1176        bounds: Bounds<Pixels>,
1177        corner_radii: Corners<Pixels>,
1178        data: Arc<ImageData>,
1179        grayscale: bool,
1180    ) -> Result<()> {
1181        let scale_factor = self.scale_factor();
1182        let bounds = bounds.scale(scale_factor);
1183        let params = RenderImageParams { image_id: data.id };
1184
1185        let tile = self
1186            .window
1187            .sprite_atlas
1188            .get_or_insert_with(&params.clone().into(), &mut || {
1189                Ok((data.size(), Cow::Borrowed(data.as_bytes())))
1190            })?;
1191        let content_mask = self.content_mask().scale(scale_factor);
1192        let corner_radii = corner_radii.scale(scale_factor);
1193
1194        let window = &mut *self.window;
1195        window.next_frame.scene_builder.insert(
1196            &window.next_frame.z_index_stack,
1197            PolychromeSprite {
1198                order: 0,
1199                bounds,
1200                content_mask,
1201                corner_radii,
1202                tile,
1203                grayscale,
1204            },
1205        );
1206        Ok(())
1207    }
1208
1209    /// Paint a surface into the scene for the next frame at the current z-index.
1210    pub fn paint_surface(&mut self, bounds: Bounds<Pixels>, image_buffer: CVImageBuffer) {
1211        let scale_factor = self.scale_factor();
1212        let bounds = bounds.scale(scale_factor);
1213        let content_mask = self.content_mask().scale(scale_factor);
1214        let window = &mut *self.window;
1215        window.next_frame.scene_builder.insert(
1216            &window.next_frame.z_index_stack,
1217            Surface {
1218                order: 0,
1219                bounds,
1220                content_mask,
1221                image_buffer,
1222            },
1223        );
1224    }
1225
1226    /// Draw pixels to the display for this window based on the contents of its scene.
1227    pub(crate) fn draw(&mut self) -> Scene {
1228        self.text_system().start_frame();
1229        self.window.platform_window.clear_input_handler();
1230        self.window.layout_engine.as_mut().unwrap().clear();
1231        self.window.next_frame.clear();
1232        let root_view = self.window.root_view.take().unwrap();
1233
1234        self.with_z_index(0, |cx| {
1235            cx.with_key_dispatch(Some(KeyContext::default()), None, |_, cx| {
1236                for (action_type, action_listeners) in &cx.app.global_action_listeners {
1237                    for action_listener in action_listeners.iter().cloned() {
1238                        cx.window.next_frame.dispatch_tree.on_action(
1239                            *action_type,
1240                            Rc::new(move |action, phase, cx| action_listener(action, phase, cx)),
1241                        )
1242                    }
1243                }
1244
1245                let available_space = cx.window.viewport_size.map(Into::into);
1246                root_view.draw(Point::default(), available_space, cx);
1247            })
1248        });
1249
1250        if let Some(active_drag) = self.app.active_drag.take() {
1251            self.with_z_index(ACTIVE_DRAG_Z_INDEX, |cx| {
1252                let offset = cx.mouse_position() - active_drag.cursor_offset;
1253                let available_space = size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1254                active_drag.view.draw(offset, available_space, cx);
1255            });
1256            self.active_drag = Some(active_drag);
1257        } else if let Some(active_tooltip) = self.app.active_tooltip.take() {
1258            self.with_z_index(1, |cx| {
1259                let available_space = size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1260                active_tooltip
1261                    .view
1262                    .draw(active_tooltip.cursor_offset, available_space, cx);
1263            });
1264        }
1265
1266        self.window
1267            .next_frame
1268            .dispatch_tree
1269            .preserve_pending_keystrokes(
1270                &mut self.window.rendered_frame.dispatch_tree,
1271                self.window.focus,
1272            );
1273        self.window.next_frame.focus = self.window.focus;
1274        self.window.root_view = Some(root_view);
1275
1276        let previous_focus_path = self.window.rendered_frame.focus_path();
1277
1278        let window = &mut self.window;
1279        mem::swap(&mut window.rendered_frame, &mut window.next_frame);
1280
1281        let current_focus_path = self.window.rendered_frame.focus_path();
1282
1283        if previous_focus_path != current_focus_path {
1284            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1285                self.window
1286                    .blur_listeners
1287                    .clone()
1288                    .retain(&(), |listener| listener(self));
1289            }
1290
1291            let event = FocusEvent {
1292                previous_focus_path,
1293                current_focus_path,
1294            };
1295            self.window
1296                .focus_listeners
1297                .clone()
1298                .retain(&(), |listener| listener(&event, self));
1299        }
1300
1301        let scene = self.window.rendered_frame.scene_builder.build();
1302
1303        // Set the cursor only if we're the active window.
1304        let cursor_style = self
1305            .window
1306            .requested_cursor_style
1307            .take()
1308            .unwrap_or(CursorStyle::Arrow);
1309        if self.is_window_active() {
1310            self.platform.set_cursor_style(cursor_style);
1311        }
1312
1313        self.window.dirty = false;
1314
1315        scene
1316    }
1317
1318    /// Dispatch a mouse or keyboard event on the window.
1319    pub fn dispatch_event(&mut self, event: InputEvent) -> bool {
1320        // Handlers may set this to false by calling `stop_propagation`.
1321        self.app.propagate_event = true;
1322        // Handlers may set this to true by calling `prevent_default`.
1323        self.window.default_prevented = false;
1324
1325        let event = match event {
1326            // Track the mouse position with our own state, since accessing the platform
1327            // API for the mouse position can only occur on the main thread.
1328            InputEvent::MouseMove(mouse_move) => {
1329                self.window.mouse_position = mouse_move.position;
1330                InputEvent::MouseMove(mouse_move)
1331            }
1332            InputEvent::MouseDown(mouse_down) => {
1333                self.window.mouse_position = mouse_down.position;
1334                InputEvent::MouseDown(mouse_down)
1335            }
1336            InputEvent::MouseUp(mouse_up) => {
1337                self.window.mouse_position = mouse_up.position;
1338                InputEvent::MouseUp(mouse_up)
1339            }
1340            // Translate dragging and dropping of external files from the operating system
1341            // to internal drag and drop events.
1342            InputEvent::FileDrop(file_drop) => match file_drop {
1343                FileDropEvent::Entered { position, files } => {
1344                    self.window.mouse_position = position;
1345                    if self.active_drag.is_none() {
1346                        self.active_drag = Some(AnyDrag {
1347                            view: self.build_view(|_| files).into(),
1348                            cursor_offset: position,
1349                        });
1350                    }
1351                    InputEvent::MouseMove(MouseMoveEvent {
1352                        position,
1353                        pressed_button: Some(MouseButton::Left),
1354                        modifiers: Modifiers::default(),
1355                    })
1356                }
1357                FileDropEvent::Pending { position } => {
1358                    self.window.mouse_position = position;
1359                    InputEvent::MouseMove(MouseMoveEvent {
1360                        position,
1361                        pressed_button: Some(MouseButton::Left),
1362                        modifiers: Modifiers::default(),
1363                    })
1364                }
1365                FileDropEvent::Submit { position } => {
1366                    self.activate(true);
1367                    self.window.mouse_position = position;
1368                    InputEvent::MouseUp(MouseUpEvent {
1369                        button: MouseButton::Left,
1370                        position,
1371                        modifiers: Modifiers::default(),
1372                        click_count: 1,
1373                    })
1374                }
1375                FileDropEvent::Exited => InputEvent::MouseUp(MouseUpEvent {
1376                    button: MouseButton::Left,
1377                    position: Point::default(),
1378                    modifiers: Modifiers::default(),
1379                    click_count: 1,
1380                }),
1381            },
1382            _ => event,
1383        };
1384
1385        if let Some(any_mouse_event) = event.mouse_event() {
1386            self.dispatch_mouse_event(any_mouse_event);
1387        } else if let Some(any_key_event) = event.keyboard_event() {
1388            self.dispatch_key_event(any_key_event);
1389        }
1390
1391        !self.app.propagate_event
1392    }
1393
1394    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1395        if let Some(mut handlers) = self
1396            .window
1397            .rendered_frame
1398            .mouse_listeners
1399            .remove(&event.type_id())
1400        {
1401            // Because handlers may add other handlers, we sort every time.
1402            handlers.sort_by(|(a, _), (b, _)| a.cmp(b));
1403
1404            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1405            // special purposes, such as detecting events outside of a given Bounds.
1406            for (_, handler) in &mut handlers {
1407                handler(event, DispatchPhase::Capture, self);
1408                if !self.app.propagate_event {
1409                    break;
1410                }
1411            }
1412
1413            // Bubble phase, where most normal handlers do their work.
1414            if self.app.propagate_event {
1415                for (_, handler) in handlers.iter_mut().rev() {
1416                    handler(event, DispatchPhase::Bubble, self);
1417                    if !self.app.propagate_event {
1418                        break;
1419                    }
1420                }
1421            }
1422
1423            if self.app.propagate_event && event.downcast_ref::<MouseUpEvent>().is_some() {
1424                self.active_drag = None;
1425            }
1426
1427            self.window
1428                .rendered_frame
1429                .mouse_listeners
1430                .insert(event.type_id(), handlers);
1431        }
1432    }
1433
1434    fn dispatch_key_event(&mut self, event: &dyn Any) {
1435        let node_id = self
1436            .window
1437            .focus
1438            .and_then(|focus_id| {
1439                self.window
1440                    .rendered_frame
1441                    .dispatch_tree
1442                    .focusable_node_id(focus_id)
1443            })
1444            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1445
1446        let dispatch_path = self
1447            .window
1448            .rendered_frame
1449            .dispatch_tree
1450            .dispatch_path(node_id);
1451
1452        let mut actions: Vec<Box<dyn Action>> = Vec::new();
1453
1454        // Capture phase
1455        let mut context_stack: SmallVec<[KeyContext; 16]> = SmallVec::new();
1456        self.propagate_event = true;
1457
1458        for node_id in &dispatch_path {
1459            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1460
1461            if let Some(context) = node.context.clone() {
1462                context_stack.push(context);
1463            }
1464
1465            for key_listener in node.key_listeners.clone() {
1466                key_listener(event, DispatchPhase::Capture, self);
1467                if !self.propagate_event {
1468                    return;
1469                }
1470            }
1471        }
1472
1473        // Bubble phase
1474        for node_id in dispatch_path.iter().rev() {
1475            // Handle low level key events
1476            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1477            for key_listener in node.key_listeners.clone() {
1478                key_listener(event, DispatchPhase::Bubble, self);
1479                if !self.propagate_event {
1480                    return;
1481                }
1482            }
1483
1484            // Match keystrokes
1485            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1486            if node.context.is_some() {
1487                if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1488                    let mut new_actions = self
1489                        .window
1490                        .rendered_frame
1491                        .dispatch_tree
1492                        .dispatch_key(&key_down_event.keystroke, &context_stack);
1493                    actions.append(&mut new_actions);
1494                }
1495
1496                context_stack.pop();
1497            }
1498        }
1499
1500        for action in actions {
1501            self.dispatch_action_on_node(node_id, action.boxed_clone());
1502            if !self.propagate_event {
1503                self.dispatch_keystroke_observers(event, Some(action));
1504                return;
1505            }
1506        }
1507        self.dispatch_keystroke_observers(event, None);
1508    }
1509
1510    pub fn has_pending_keystrokes(&self) -> bool {
1511        self.window
1512            .rendered_frame
1513            .dispatch_tree
1514            .has_pending_keystrokes()
1515    }
1516
1517    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: Box<dyn Action>) {
1518        let dispatch_path = self
1519            .window
1520            .rendered_frame
1521            .dispatch_tree
1522            .dispatch_path(node_id);
1523
1524        // Capture phase
1525        for node_id in &dispatch_path {
1526            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1527            for DispatchActionListener {
1528                action_type,
1529                listener,
1530            } in node.action_listeners.clone()
1531            {
1532                let any_action = action.as_any();
1533                if action_type == any_action.type_id() {
1534                    listener(any_action, DispatchPhase::Capture, self);
1535                    if !self.propagate_event {
1536                        return;
1537                    }
1538                }
1539            }
1540        }
1541        // Bubble phase
1542        for node_id in dispatch_path.iter().rev() {
1543            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1544            for DispatchActionListener {
1545                action_type,
1546                listener,
1547            } in node.action_listeners.clone()
1548            {
1549                let any_action = action.as_any();
1550                if action_type == any_action.type_id() {
1551                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1552                    listener(any_action, DispatchPhase::Bubble, self);
1553                    if !self.propagate_event {
1554                        return;
1555                    }
1556                }
1557            }
1558        }
1559    }
1560
1561    /// Register the given handler to be invoked whenever the global of the given type
1562    /// is updated.
1563    pub fn observe_global<G: 'static>(
1564        &mut self,
1565        f: impl Fn(&mut WindowContext<'_>) + 'static,
1566    ) -> Subscription {
1567        let window_handle = self.window.handle;
1568        let (subscription, activate) = self.global_observers.insert(
1569            TypeId::of::<G>(),
1570            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1571        );
1572        self.app.defer(move |_| activate());
1573        subscription
1574    }
1575
1576    pub fn activate_window(&self) {
1577        self.window.platform_window.activate();
1578    }
1579
1580    pub fn minimize_window(&self) {
1581        self.window.platform_window.minimize();
1582    }
1583
1584    pub fn toggle_full_screen(&self) {
1585        self.window.platform_window.toggle_full_screen();
1586    }
1587
1588    pub fn prompt(
1589        &self,
1590        level: PromptLevel,
1591        msg: &str,
1592        answers: &[&str],
1593    ) -> oneshot::Receiver<usize> {
1594        self.window.platform_window.prompt(level, msg, answers)
1595    }
1596
1597    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1598        let node_id = self
1599            .window
1600            .focus
1601            .and_then(|focus_id| {
1602                self.window
1603                    .rendered_frame
1604                    .dispatch_tree
1605                    .focusable_node_id(focus_id)
1606            })
1607            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1608
1609        self.window
1610            .rendered_frame
1611            .dispatch_tree
1612            .available_actions(node_id)
1613    }
1614
1615    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1616        self.window
1617            .rendered_frame
1618            .dispatch_tree
1619            .bindings_for_action(
1620                action,
1621                &self.window.rendered_frame.dispatch_tree.context_stack,
1622            )
1623    }
1624
1625    pub fn bindings_for_action_in(
1626        &self,
1627        action: &dyn Action,
1628        focus_handle: &FocusHandle,
1629    ) -> Vec<KeyBinding> {
1630        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1631
1632        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1633            return vec![];
1634        };
1635        let context_stack = dispatch_tree
1636            .dispatch_path(node_id)
1637            .into_iter()
1638            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1639            .collect();
1640        dispatch_tree.bindings_for_action(action, &context_stack)
1641    }
1642
1643    pub fn listener_for<V: Render, E>(
1644        &self,
1645        view: &View<V>,
1646        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1647    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1648        let view = view.downgrade();
1649        move |e: &E, cx: &mut WindowContext| {
1650            view.update(cx, |view, cx| f(view, e, cx)).ok();
1651        }
1652    }
1653
1654    pub fn handler_for<V: Render>(
1655        &self,
1656        view: &View<V>,
1657        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1658    ) -> impl Fn(&mut WindowContext) {
1659        let view = view.downgrade();
1660        move |cx: &mut WindowContext| {
1661            view.update(cx, |view, cx| f(view, cx)).ok();
1662        }
1663    }
1664
1665    //========== ELEMENT RELATED FUNCTIONS ===========
1666    pub fn with_key_dispatch<R>(
1667        &mut self,
1668        context: Option<KeyContext>,
1669        focus_handle: Option<FocusHandle>,
1670        f: impl FnOnce(Option<FocusHandle>, &mut Self) -> R,
1671    ) -> R {
1672        let window = &mut self.window;
1673        window.next_frame.dispatch_tree.push_node(context.clone());
1674        if let Some(focus_handle) = focus_handle.as_ref() {
1675            window
1676                .next_frame
1677                .dispatch_tree
1678                .make_focusable(focus_handle.id);
1679        }
1680        let result = f(focus_handle, self);
1681
1682        self.window.next_frame.dispatch_tree.pop_node();
1683
1684        result
1685    }
1686
1687    /// Set an input handler, such as [ElementInputHandler], which interfaces with the
1688    /// platform to receive textual input with proper integration with concerns such
1689    /// as IME interactions.
1690    pub fn handle_input(
1691        &mut self,
1692        focus_handle: &FocusHandle,
1693        input_handler: impl PlatformInputHandler,
1694    ) {
1695        if focus_handle.is_focused(self) {
1696            self.window
1697                .platform_window
1698                .set_input_handler(Box::new(input_handler));
1699        }
1700    }
1701
1702    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1703        let mut this = self.to_async();
1704        self.window
1705            .platform_window
1706            .on_should_close(Box::new(move || this.update(|_, cx| f(cx)).unwrap_or(true)))
1707    }
1708}
1709
1710impl Context for WindowContext<'_> {
1711    type Result<T> = T;
1712
1713    fn build_model<T>(
1714        &mut self,
1715        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
1716    ) -> Model<T>
1717    where
1718        T: 'static,
1719    {
1720        let slot = self.app.entities.reserve();
1721        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1722        self.entities.insert(slot, model)
1723    }
1724
1725    fn update_model<T: 'static, R>(
1726        &mut self,
1727        model: &Model<T>,
1728        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1729    ) -> R {
1730        let mut entity = self.entities.lease(model);
1731        let result = update(
1732            &mut *entity,
1733            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1734        );
1735        self.entities.end_lease(entity);
1736        result
1737    }
1738
1739    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1740    where
1741        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1742    {
1743        if window == self.window.handle {
1744            let root_view = self.window.root_view.clone().unwrap();
1745            Ok(update(root_view, self))
1746        } else {
1747            window.update(self.app, update)
1748        }
1749    }
1750
1751    fn read_model<T, R>(
1752        &self,
1753        handle: &Model<T>,
1754        read: impl FnOnce(&T, &AppContext) -> R,
1755    ) -> Self::Result<R>
1756    where
1757        T: 'static,
1758    {
1759        let entity = self.entities.read(handle);
1760        read(&*entity, &*self.app)
1761    }
1762
1763    fn read_window<T, R>(
1764        &self,
1765        window: &WindowHandle<T>,
1766        read: impl FnOnce(View<T>, &AppContext) -> R,
1767    ) -> Result<R>
1768    where
1769        T: 'static,
1770    {
1771        if window.any_handle == self.window.handle {
1772            let root_view = self
1773                .window
1774                .root_view
1775                .clone()
1776                .unwrap()
1777                .downcast::<T>()
1778                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1779            Ok(read(root_view, self))
1780        } else {
1781            self.app.read_window(window, read)
1782        }
1783    }
1784}
1785
1786impl VisualContext for WindowContext<'_> {
1787    fn build_view<V>(
1788        &mut self,
1789        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1790    ) -> Self::Result<View<V>>
1791    where
1792        V: 'static + Render,
1793    {
1794        let slot = self.app.entities.reserve();
1795        let view = View {
1796            model: slot.clone(),
1797        };
1798        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1799        let entity = build_view_state(&mut cx);
1800        cx.entities.insert(slot, entity);
1801
1802        cx.new_view_observers
1803            .clone()
1804            .retain(&TypeId::of::<V>(), |observer| {
1805                let any_view = AnyView::from(view.clone());
1806                (observer)(any_view, self);
1807                true
1808            });
1809
1810        view
1811    }
1812
1813    /// Update the given view. Prefer calling `View::update` instead, which calls this method.
1814    fn update_view<T: 'static, R>(
1815        &mut self,
1816        view: &View<T>,
1817        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1818    ) -> Self::Result<R> {
1819        let mut lease = self.app.entities.lease(&view.model);
1820        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1821        let result = update(&mut *lease, &mut cx);
1822        cx.app.entities.end_lease(lease);
1823        result
1824    }
1825
1826    fn replace_root_view<V>(
1827        &mut self,
1828        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1829    ) -> Self::Result<View<V>>
1830    where
1831        V: 'static + Render,
1832    {
1833        let slot = self.app.entities.reserve();
1834        let view = View {
1835            model: slot.clone(),
1836        };
1837        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1838        let entity = build_view(&mut cx);
1839        self.entities.insert(slot, entity);
1840        self.window.root_view = Some(view.clone().into());
1841        view
1842    }
1843
1844    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1845        self.update_view(view, |view, cx| {
1846            view.focus_handle(cx).clone().focus(cx);
1847        })
1848    }
1849
1850    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1851    where
1852        V: ManagedView,
1853    {
1854        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1855    }
1856}
1857
1858impl<'a> std::ops::Deref for WindowContext<'a> {
1859    type Target = AppContext;
1860
1861    fn deref(&self) -> &Self::Target {
1862        &self.app
1863    }
1864}
1865
1866impl<'a> std::ops::DerefMut for WindowContext<'a> {
1867    fn deref_mut(&mut self) -> &mut Self::Target {
1868        &mut self.app
1869    }
1870}
1871
1872impl<'a> Borrow<AppContext> for WindowContext<'a> {
1873    fn borrow(&self) -> &AppContext {
1874        &self.app
1875    }
1876}
1877
1878impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1879    fn borrow_mut(&mut self) -> &mut AppContext {
1880        &mut self.app
1881    }
1882}
1883
1884pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1885    fn app_mut(&mut self) -> &mut AppContext {
1886        self.borrow_mut()
1887    }
1888
1889    fn app(&self) -> &AppContext {
1890        self.borrow()
1891    }
1892
1893    fn window(&self) -> &Window {
1894        self.borrow()
1895    }
1896
1897    fn window_mut(&mut self) -> &mut Window {
1898        self.borrow_mut()
1899    }
1900
1901    /// Pushes the given element id onto the global stack and invokes the given closure
1902    /// with a `GlobalElementId`, which disambiguates the given id in the context of its ancestor
1903    /// ids. Because elements are discarded and recreated on each frame, the `GlobalElementId` is
1904    /// used to associate state with identified elements across separate frames.
1905    fn with_element_id<R>(
1906        &mut self,
1907        id: Option<impl Into<ElementId>>,
1908        f: impl FnOnce(&mut Self) -> R,
1909    ) -> R {
1910        if let Some(id) = id.map(Into::into) {
1911            let window = self.window_mut();
1912            window.element_id_stack.push(id.into());
1913            let result = f(self);
1914            let window: &mut Window = self.borrow_mut();
1915            window.element_id_stack.pop();
1916            result
1917        } else {
1918            f(self)
1919        }
1920    }
1921
1922    /// Invoke the given function with the given content mask after intersecting it
1923    /// with the current mask.
1924    fn with_content_mask<R>(
1925        &mut self,
1926        mask: Option<ContentMask<Pixels>>,
1927        f: impl FnOnce(&mut Self) -> R,
1928    ) -> R {
1929        if let Some(mask) = mask {
1930            let mask = mask.intersect(&self.content_mask());
1931            self.window_mut().next_frame.content_mask_stack.push(mask);
1932            let result = f(self);
1933            self.window_mut().next_frame.content_mask_stack.pop();
1934            result
1935        } else {
1936            f(self)
1937        }
1938    }
1939
1940    /// Invoke the given function with the content mask reset to that
1941    /// of the window.
1942    fn break_content_mask<R>(&mut self, f: impl FnOnce(&mut Self) -> R) -> R {
1943        let mask = ContentMask {
1944            bounds: Bounds {
1945                origin: Point::default(),
1946                size: self.window().viewport_size,
1947            },
1948        };
1949        self.window_mut().next_frame.content_mask_stack.push(mask);
1950        let result = f(self);
1951        self.window_mut().next_frame.content_mask_stack.pop();
1952        result
1953    }
1954
1955    /// Update the global element offset relative to the current offset. This is used to implement
1956    /// scrolling.
1957    fn with_element_offset<R>(
1958        &mut self,
1959        offset: Point<Pixels>,
1960        f: impl FnOnce(&mut Self) -> R,
1961    ) -> R {
1962        if offset.is_zero() {
1963            return f(self);
1964        };
1965
1966        let abs_offset = self.element_offset() + offset;
1967        self.with_absolute_element_offset(abs_offset, f)
1968    }
1969
1970    /// Update the global element offset based on the given offset. This is used to implement
1971    /// drag handles and other manual painting of elements.
1972    fn with_absolute_element_offset<R>(
1973        &mut self,
1974        offset: Point<Pixels>,
1975        f: impl FnOnce(&mut Self) -> R,
1976    ) -> R {
1977        self.window_mut()
1978            .next_frame
1979            .element_offset_stack
1980            .push(offset);
1981        let result = f(self);
1982        self.window_mut().next_frame.element_offset_stack.pop();
1983        result
1984    }
1985
1986    /// Obtain the current element offset.
1987    fn element_offset(&self) -> Point<Pixels> {
1988        self.window()
1989            .next_frame
1990            .element_offset_stack
1991            .last()
1992            .copied()
1993            .unwrap_or_default()
1994    }
1995
1996    /// Update or initialize state for an element with the given id that lives across multiple
1997    /// frames. If an element with this id existed in the rendered frame, its state will be passed
1998    /// to the given closure. The state returned by the closure will be stored so it can be referenced
1999    /// when drawing the next frame.
2000    fn with_element_state<S, R>(
2001        &mut self,
2002        id: ElementId,
2003        f: impl FnOnce(Option<S>, &mut Self) -> (R, S),
2004    ) -> R
2005    where
2006        S: 'static,
2007    {
2008        self.with_element_id(Some(id), |cx| {
2009            let global_id = cx.window().element_id_stack.clone();
2010
2011            if let Some(any) = cx
2012                .window_mut()
2013                .next_frame
2014                .element_states
2015                .remove(&global_id)
2016                .or_else(|| {
2017                    cx.window_mut()
2018                        .rendered_frame
2019                        .element_states
2020                        .remove(&global_id)
2021                })
2022            {
2023                let ElementStateBox {
2024                    inner,
2025
2026                    #[cfg(debug_assertions)]
2027                    type_name
2028                } = any;
2029                // Using the extra inner option to avoid needing to reallocate a new box.
2030                let mut state_box = inner
2031                    .downcast::<Option<S>>()
2032                    .map_err(|_| {
2033                        #[cfg(debug_assertions)]
2034                        {
2035                            anyhow!(
2036                                "invalid element state type for id, requested_type {:?}, actual type: {:?}",
2037                                std::any::type_name::<S>(),
2038                                type_name
2039                            )
2040                        }
2041
2042                        #[cfg(not(debug_assertions))]
2043                        {
2044                            anyhow!(
2045                                "invalid element state type for id, requested_type {:?}",
2046                                std::any::type_name::<S>(),
2047                            )
2048                        }
2049                    })
2050                    .unwrap();
2051
2052                // Actual: Option<AnyElement> <- View
2053                // Requested: () <- AnyElemet
2054                let state = state_box
2055                    .take()
2056                    .expect("element state is already on the stack");
2057                let (result, state) = f(Some(state), cx);
2058                state_box.replace(state);
2059                cx.window_mut()
2060                    .next_frame
2061                    .element_states
2062                    .insert(global_id, ElementStateBox {
2063                        inner: state_box,
2064
2065                        #[cfg(debug_assertions)]
2066                        type_name
2067                    });
2068                result
2069            } else {
2070                let (result, state) = f(None, cx);
2071                cx.window_mut()
2072                    .next_frame
2073                    .element_states
2074                    .insert(global_id,
2075                        ElementStateBox {
2076                            inner: Box::new(Some(state)),
2077
2078                            #[cfg(debug_assertions)]
2079                            type_name: std::any::type_name::<S>()
2080                        }
2081
2082                    );
2083                result
2084            }
2085        })
2086    }
2087
2088    /// Obtain the current content mask.
2089    fn content_mask(&self) -> ContentMask<Pixels> {
2090        self.window()
2091            .next_frame
2092            .content_mask_stack
2093            .last()
2094            .cloned()
2095            .unwrap_or_else(|| ContentMask {
2096                bounds: Bounds {
2097                    origin: Point::default(),
2098                    size: self.window().viewport_size,
2099                },
2100            })
2101    }
2102
2103    /// The size of an em for the base font of the application. Adjusting this value allows the
2104    /// UI to scale, just like zooming a web page.
2105    fn rem_size(&self) -> Pixels {
2106        self.window().rem_size
2107    }
2108}
2109
2110impl Borrow<Window> for WindowContext<'_> {
2111    fn borrow(&self) -> &Window {
2112        &self.window
2113    }
2114}
2115
2116impl BorrowMut<Window> for WindowContext<'_> {
2117    fn borrow_mut(&mut self) -> &mut Window {
2118        &mut self.window
2119    }
2120}
2121
2122impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
2123
2124pub struct ViewContext<'a, V> {
2125    window_cx: WindowContext<'a>,
2126    view: &'a View<V>,
2127}
2128
2129impl<V> Borrow<AppContext> for ViewContext<'_, V> {
2130    fn borrow(&self) -> &AppContext {
2131        &*self.window_cx.app
2132    }
2133}
2134
2135impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
2136    fn borrow_mut(&mut self) -> &mut AppContext {
2137        &mut *self.window_cx.app
2138    }
2139}
2140
2141impl<V> Borrow<Window> for ViewContext<'_, V> {
2142    fn borrow(&self) -> &Window {
2143        &*self.window_cx.window
2144    }
2145}
2146
2147impl<V> BorrowMut<Window> for ViewContext<'_, V> {
2148    fn borrow_mut(&mut self) -> &mut Window {
2149        &mut *self.window_cx.window
2150    }
2151}
2152
2153impl<'a, V: 'static> ViewContext<'a, V> {
2154    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
2155        Self {
2156            window_cx: WindowContext::new(app, window),
2157            view,
2158        }
2159    }
2160
2161    pub fn entity_id(&self) -> EntityId {
2162        self.view.entity_id()
2163    }
2164
2165    pub fn view(&self) -> &View<V> {
2166        self.view
2167    }
2168
2169    pub fn model(&self) -> &Model<V> {
2170        &self.view.model
2171    }
2172
2173    /// Access the underlying window context.
2174    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2175        &mut self.window_cx
2176    }
2177
2178    pub fn with_z_index<R>(&mut self, z_index: u32, f: impl FnOnce(&mut Self) -> R) -> R {
2179        self.window.next_frame.z_index_stack.push(z_index);
2180        let result = f(self);
2181        self.window.next_frame.z_index_stack.pop();
2182        result
2183    }
2184
2185    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
2186    where
2187        V: 'static,
2188    {
2189        let view = self.view().clone();
2190        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
2191    }
2192
2193    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
2194    /// that are currently on the stack to be returned to the app.
2195    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
2196        let view = self.view().downgrade();
2197        self.window_cx.defer(move |cx| {
2198            view.update(cx, f).ok();
2199        });
2200    }
2201
2202    pub fn observe<V2, E>(
2203        &mut self,
2204        entity: &E,
2205        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
2206    ) -> Subscription
2207    where
2208        V2: 'static,
2209        V: 'static,
2210        E: Entity<V2>,
2211    {
2212        let view = self.view().downgrade();
2213        let entity_id = entity.entity_id();
2214        let entity = entity.downgrade();
2215        let window_handle = self.window.handle;
2216        let (subscription, activate) = self.app.observers.insert(
2217            entity_id,
2218            Box::new(move |cx| {
2219                window_handle
2220                    .update(cx, |_, cx| {
2221                        if let Some(handle) = E::upgrade_from(&entity) {
2222                            view.update(cx, |this, cx| on_notify(this, handle, cx))
2223                                .is_ok()
2224                        } else {
2225                            false
2226                        }
2227                    })
2228                    .unwrap_or(false)
2229            }),
2230        );
2231        self.app.defer(move |_| activate());
2232        subscription
2233    }
2234
2235    pub fn subscribe<V2, E, Evt>(
2236        &mut self,
2237        entity: &E,
2238        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2239    ) -> Subscription
2240    where
2241        V2: EventEmitter<Evt>,
2242        E: Entity<V2>,
2243        Evt: 'static,
2244    {
2245        let view = self.view().downgrade();
2246        let entity_id = entity.entity_id();
2247        let handle = entity.downgrade();
2248        let window_handle = self.window.handle;
2249        let (subscription, activate) = self.app.event_listeners.insert(
2250            entity_id,
2251            (
2252                TypeId::of::<Evt>(),
2253                Box::new(move |event, cx| {
2254                    window_handle
2255                        .update(cx, |_, cx| {
2256                            if let Some(handle) = E::upgrade_from(&handle) {
2257                                let event = event.downcast_ref().expect("invalid event type");
2258                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2259                                    .is_ok()
2260                            } else {
2261                                false
2262                            }
2263                        })
2264                        .unwrap_or(false)
2265                }),
2266            ),
2267        );
2268        self.app.defer(move |_| activate());
2269        subscription
2270    }
2271
2272    pub fn on_release(
2273        &mut self,
2274        on_release: impl FnOnce(&mut V, &mut WindowContext) + 'static,
2275    ) -> Subscription {
2276        let window_handle = self.window.handle;
2277        let (subscription, activate) = self.app.release_listeners.insert(
2278            self.view.model.entity_id,
2279            Box::new(move |this, cx| {
2280                let this = this.downcast_mut().expect("invalid entity type");
2281                let _ = window_handle.update(cx, |_, cx| on_release(this, cx));
2282            }),
2283        );
2284        activate();
2285        subscription
2286    }
2287
2288    pub fn observe_release<V2, E>(
2289        &mut self,
2290        entity: &E,
2291        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2292    ) -> Subscription
2293    where
2294        V: 'static,
2295        V2: 'static,
2296        E: Entity<V2>,
2297    {
2298        let view = self.view().downgrade();
2299        let entity_id = entity.entity_id();
2300        let window_handle = self.window.handle;
2301        let (subscription, activate) = self.app.release_listeners.insert(
2302            entity_id,
2303            Box::new(move |entity, cx| {
2304                let entity = entity.downcast_mut().expect("invalid entity type");
2305                let _ = window_handle.update(cx, |_, cx| {
2306                    view.update(cx, |this, cx| on_release(this, entity, cx))
2307                });
2308            }),
2309        );
2310        activate();
2311        subscription
2312    }
2313
2314    pub fn notify(&mut self) {
2315        self.window_cx.notify();
2316        self.window_cx.app.push_effect(Effect::Notify {
2317            emitter: self.view.model.entity_id,
2318        });
2319    }
2320
2321    pub fn observe_window_bounds(
2322        &mut self,
2323        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2324    ) -> Subscription {
2325        let view = self.view.downgrade();
2326        let (subscription, activate) = self.window.bounds_observers.insert(
2327            (),
2328            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2329        );
2330        activate();
2331        subscription
2332    }
2333
2334    pub fn observe_window_activation(
2335        &mut self,
2336        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2337    ) -> Subscription {
2338        let view = self.view.downgrade();
2339        let (subscription, activate) = self.window.activation_observers.insert(
2340            (),
2341            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2342        );
2343        activate();
2344        subscription
2345    }
2346
2347    /// Register a listener to be called when the given focus handle receives focus.
2348    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2349    /// is dropped.
2350    pub fn on_focus(
2351        &mut self,
2352        handle: &FocusHandle,
2353        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2354    ) -> Subscription {
2355        let view = self.view.downgrade();
2356        let focus_id = handle.id;
2357        let (subscription, activate) = self.window.focus_listeners.insert(
2358            (),
2359            Box::new(move |event, cx| {
2360                view.update(cx, |view, cx| {
2361                    if event.previous_focus_path.last() != Some(&focus_id)
2362                        && event.current_focus_path.last() == Some(&focus_id)
2363                    {
2364                        listener(view, cx)
2365                    }
2366                })
2367                .is_ok()
2368            }),
2369        );
2370        self.app.defer(move |_| activate());
2371        subscription
2372    }
2373
2374    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2375    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2376    /// is dropped.
2377    pub fn on_focus_in(
2378        &mut self,
2379        handle: &FocusHandle,
2380        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2381    ) -> Subscription {
2382        let view = self.view.downgrade();
2383        let focus_id = handle.id;
2384        let (subscription, activate) = self.window.focus_listeners.insert(
2385            (),
2386            Box::new(move |event, cx| {
2387                view.update(cx, |view, cx| {
2388                    if !event.previous_focus_path.contains(&focus_id)
2389                        && event.current_focus_path.contains(&focus_id)
2390                    {
2391                        listener(view, cx)
2392                    }
2393                })
2394                .is_ok()
2395            }),
2396        );
2397        self.app.defer(move |_| activate());
2398        subscription
2399    }
2400
2401    /// Register a listener to be called when the given focus handle loses focus.
2402    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2403    /// is dropped.
2404    pub fn on_blur(
2405        &mut self,
2406        handle: &FocusHandle,
2407        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2408    ) -> Subscription {
2409        let view = self.view.downgrade();
2410        let focus_id = handle.id;
2411        let (subscription, activate) = self.window.focus_listeners.insert(
2412            (),
2413            Box::new(move |event, cx| {
2414                view.update(cx, |view, cx| {
2415                    if event.previous_focus_path.last() == Some(&focus_id)
2416                        && event.current_focus_path.last() != Some(&focus_id)
2417                    {
2418                        listener(view, cx)
2419                    }
2420                })
2421                .is_ok()
2422            }),
2423        );
2424        self.app.defer(move |_| activate());
2425        subscription
2426    }
2427
2428    /// Register a listener to be called when the window loses focus.
2429    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2430    /// is dropped.
2431    pub fn on_blur_window(
2432        &mut self,
2433        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2434    ) -> Subscription {
2435        let view = self.view.downgrade();
2436        let (subscription, activate) = self.window.blur_listeners.insert(
2437            (),
2438            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2439        );
2440        activate();
2441        subscription
2442    }
2443
2444    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2445    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2446    /// is dropped.
2447    pub fn on_focus_out(
2448        &mut self,
2449        handle: &FocusHandle,
2450        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2451    ) -> Subscription {
2452        let view = self.view.downgrade();
2453        let focus_id = handle.id;
2454        let (subscription, activate) = self.window.focus_listeners.insert(
2455            (),
2456            Box::new(move |event, cx| {
2457                view.update(cx, |view, cx| {
2458                    if event.previous_focus_path.contains(&focus_id)
2459                        && !event.current_focus_path.contains(&focus_id)
2460                    {
2461                        listener(view, cx)
2462                    }
2463                })
2464                .is_ok()
2465            }),
2466        );
2467        self.app.defer(move |_| activate());
2468        subscription
2469    }
2470
2471    pub fn spawn<Fut, R>(
2472        &mut self,
2473        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2474    ) -> Task<R>
2475    where
2476        R: 'static,
2477        Fut: Future<Output = R> + 'static,
2478    {
2479        let view = self.view().downgrade();
2480        self.window_cx.spawn(|cx| f(view, cx))
2481    }
2482
2483    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2484    where
2485        G: 'static,
2486    {
2487        let mut global = self.app.lease_global::<G>();
2488        let result = f(&mut global, self);
2489        self.app.end_global_lease(global);
2490        result
2491    }
2492
2493    pub fn observe_global<G: 'static>(
2494        &mut self,
2495        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2496    ) -> Subscription {
2497        let window_handle = self.window.handle;
2498        let view = self.view().downgrade();
2499        let (subscription, activate) = self.global_observers.insert(
2500            TypeId::of::<G>(),
2501            Box::new(move |cx| {
2502                window_handle
2503                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2504                    .unwrap_or(false)
2505            }),
2506        );
2507        self.app.defer(move |_| activate());
2508        subscription
2509    }
2510
2511    pub fn on_mouse_event<Event: 'static>(
2512        &mut self,
2513        handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
2514    ) {
2515        let handle = self.view().clone();
2516        self.window_cx.on_mouse_event(move |event, phase, cx| {
2517            handle.update(cx, |view, cx| {
2518                handler(view, event, phase, cx);
2519            })
2520        });
2521    }
2522
2523    pub fn on_key_event<Event: 'static>(
2524        &mut self,
2525        handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
2526    ) {
2527        let handle = self.view().clone();
2528        self.window_cx.on_key_event(move |event, phase, cx| {
2529            handle.update(cx, |view, cx| {
2530                handler(view, event, phase, cx);
2531            })
2532        });
2533    }
2534
2535    pub fn on_action(
2536        &mut self,
2537        action_type: TypeId,
2538        handler: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2539    ) {
2540        let handle = self.view().clone();
2541        self.window_cx
2542            .on_action(action_type, move |action, phase, cx| {
2543                handle.update(cx, |view, cx| {
2544                    handler(view, action, phase, cx);
2545                })
2546            });
2547    }
2548
2549    pub fn emit<Evt>(&mut self, event: Evt)
2550    where
2551        Evt: 'static,
2552        V: EventEmitter<Evt>,
2553    {
2554        let emitter = self.view.model.entity_id;
2555        self.app.push_effect(Effect::Emit {
2556            emitter,
2557            event_type: TypeId::of::<Evt>(),
2558            event: Box::new(event),
2559        });
2560    }
2561
2562    pub fn focus_self(&mut self)
2563    where
2564        V: FocusableView,
2565    {
2566        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2567    }
2568
2569    pub fn dismiss_self(&mut self)
2570    where
2571        V: ManagedView,
2572    {
2573        self.defer(|_, cx| cx.emit(DismissEvent))
2574    }
2575
2576    pub fn listener<E>(
2577        &self,
2578        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2579    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2580        let view = self.view().downgrade();
2581        move |e: &E, cx: &mut WindowContext| {
2582            view.update(cx, |view, cx| f(view, e, cx)).ok();
2583        }
2584    }
2585}
2586
2587impl<V> Context for ViewContext<'_, V> {
2588    type Result<U> = U;
2589
2590    fn build_model<T: 'static>(
2591        &mut self,
2592        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2593    ) -> Model<T> {
2594        self.window_cx.build_model(build_model)
2595    }
2596
2597    fn update_model<T: 'static, R>(
2598        &mut self,
2599        model: &Model<T>,
2600        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2601    ) -> R {
2602        self.window_cx.update_model(model, update)
2603    }
2604
2605    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2606    where
2607        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2608    {
2609        self.window_cx.update_window(window, update)
2610    }
2611
2612    fn read_model<T, R>(
2613        &self,
2614        handle: &Model<T>,
2615        read: impl FnOnce(&T, &AppContext) -> R,
2616    ) -> Self::Result<R>
2617    where
2618        T: 'static,
2619    {
2620        self.window_cx.read_model(handle, read)
2621    }
2622
2623    fn read_window<T, R>(
2624        &self,
2625        window: &WindowHandle<T>,
2626        read: impl FnOnce(View<T>, &AppContext) -> R,
2627    ) -> Result<R>
2628    where
2629        T: 'static,
2630    {
2631        self.window_cx.read_window(window, read)
2632    }
2633}
2634
2635impl<V: 'static> VisualContext for ViewContext<'_, V> {
2636    fn build_view<W: Render + 'static>(
2637        &mut self,
2638        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2639    ) -> Self::Result<View<W>> {
2640        self.window_cx.build_view(build_view_state)
2641    }
2642
2643    fn update_view<V2: 'static, R>(
2644        &mut self,
2645        view: &View<V2>,
2646        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2647    ) -> Self::Result<R> {
2648        self.window_cx.update_view(view, update)
2649    }
2650
2651    fn replace_root_view<W>(
2652        &mut self,
2653        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2654    ) -> Self::Result<View<W>>
2655    where
2656        W: 'static + Render,
2657    {
2658        self.window_cx.replace_root_view(build_view)
2659    }
2660
2661    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2662        self.window_cx.focus_view(view)
2663    }
2664
2665    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2666        self.window_cx.dismiss_view(view)
2667    }
2668}
2669
2670impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2671    type Target = WindowContext<'a>;
2672
2673    fn deref(&self) -> &Self::Target {
2674        &self.window_cx
2675    }
2676}
2677
2678impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2679    fn deref_mut(&mut self) -> &mut Self::Target {
2680        &mut self.window_cx
2681    }
2682}
2683
2684// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2685slotmap::new_key_type! { pub struct WindowId; }
2686
2687impl WindowId {
2688    pub fn as_u64(&self) -> u64 {
2689        self.0.as_ffi()
2690    }
2691}
2692
2693#[derive(Deref, DerefMut)]
2694pub struct WindowHandle<V> {
2695    #[deref]
2696    #[deref_mut]
2697    pub(crate) any_handle: AnyWindowHandle,
2698    state_type: PhantomData<V>,
2699}
2700
2701impl<V: 'static + Render> WindowHandle<V> {
2702    pub fn new(id: WindowId) -> Self {
2703        WindowHandle {
2704            any_handle: AnyWindowHandle {
2705                id,
2706                state_type: TypeId::of::<V>(),
2707            },
2708            state_type: PhantomData,
2709        }
2710    }
2711
2712    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2713    where
2714        C: Context,
2715    {
2716        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2717            root_view
2718                .downcast::<V>()
2719                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2720        }))
2721    }
2722
2723    pub fn update<C, R>(
2724        &self,
2725        cx: &mut C,
2726        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2727    ) -> Result<R>
2728    where
2729        C: Context,
2730    {
2731        cx.update_window(self.any_handle, |root_view, cx| {
2732            let view = root_view
2733                .downcast::<V>()
2734                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2735            Ok(cx.update_view(&view, update))
2736        })?
2737    }
2738
2739    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2740        let x = cx
2741            .windows
2742            .get(self.id)
2743            .and_then(|window| {
2744                window
2745                    .as_ref()
2746                    .and_then(|window| window.root_view.clone())
2747                    .map(|root_view| root_view.downcast::<V>())
2748            })
2749            .ok_or_else(|| anyhow!("window not found"))?
2750            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2751
2752        Ok(x.read(cx))
2753    }
2754
2755    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2756    where
2757        C: Context,
2758    {
2759        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2760    }
2761
2762    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2763    where
2764        C: Context,
2765    {
2766        cx.read_window(self, |root_view, _cx| root_view.clone())
2767    }
2768
2769    pub fn is_active(&self, cx: &AppContext) -> Option<bool> {
2770        cx.windows
2771            .get(self.id)
2772            .and_then(|window| window.as_ref().map(|window| window.active))
2773    }
2774}
2775
2776impl<V> Copy for WindowHandle<V> {}
2777
2778impl<V> Clone for WindowHandle<V> {
2779    fn clone(&self) -> Self {
2780        WindowHandle {
2781            any_handle: self.any_handle,
2782            state_type: PhantomData,
2783        }
2784    }
2785}
2786
2787impl<V> PartialEq for WindowHandle<V> {
2788    fn eq(&self, other: &Self) -> bool {
2789        self.any_handle == other.any_handle
2790    }
2791}
2792
2793impl<V> Eq for WindowHandle<V> {}
2794
2795impl<V> Hash for WindowHandle<V> {
2796    fn hash<H: Hasher>(&self, state: &mut H) {
2797        self.any_handle.hash(state);
2798    }
2799}
2800
2801impl<V: 'static> Into<AnyWindowHandle> for WindowHandle<V> {
2802    fn into(self) -> AnyWindowHandle {
2803        self.any_handle
2804    }
2805}
2806
2807#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2808pub struct AnyWindowHandle {
2809    pub(crate) id: WindowId,
2810    state_type: TypeId,
2811}
2812
2813impl AnyWindowHandle {
2814    pub fn window_id(&self) -> WindowId {
2815        self.id
2816    }
2817
2818    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2819        if TypeId::of::<T>() == self.state_type {
2820            Some(WindowHandle {
2821                any_handle: *self,
2822                state_type: PhantomData,
2823            })
2824        } else {
2825            None
2826        }
2827    }
2828
2829    pub fn update<C, R>(
2830        self,
2831        cx: &mut C,
2832        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2833    ) -> Result<R>
2834    where
2835        C: Context,
2836    {
2837        cx.update_window(self, update)
2838    }
2839
2840    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2841    where
2842        C: Context,
2843        T: 'static,
2844    {
2845        let view = self
2846            .downcast::<T>()
2847            .context("the type of the window's root view has changed")?;
2848
2849        cx.read_window(&view, read)
2850    }
2851}
2852
2853#[cfg(any(test, feature = "test-support"))]
2854impl From<SmallVec<[u32; 16]>> for StackingOrder {
2855    fn from(small_vec: SmallVec<[u32; 16]>) -> Self {
2856        StackingOrder(small_vec)
2857    }
2858}
2859
2860#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2861pub enum ElementId {
2862    View(EntityId),
2863    Integer(usize),
2864    Name(SharedString),
2865    FocusHandle(FocusId),
2866    NamedInteger(SharedString, usize),
2867}
2868
2869impl ElementId {
2870    pub(crate) fn from_entity_id(entity_id: EntityId) -> Self {
2871        ElementId::View(entity_id)
2872    }
2873}
2874
2875impl TryInto<SharedString> for ElementId {
2876    type Error = anyhow::Error;
2877
2878    fn try_into(self) -> anyhow::Result<SharedString> {
2879        if let ElementId::Name(name) = self {
2880            Ok(name)
2881        } else {
2882            Err(anyhow!("element id is not string"))
2883        }
2884    }
2885}
2886
2887impl From<usize> for ElementId {
2888    fn from(id: usize) -> Self {
2889        ElementId::Integer(id)
2890    }
2891}
2892
2893impl From<i32> for ElementId {
2894    fn from(id: i32) -> Self {
2895        Self::Integer(id as usize)
2896    }
2897}
2898
2899impl From<SharedString> for ElementId {
2900    fn from(name: SharedString) -> Self {
2901        ElementId::Name(name)
2902    }
2903}
2904
2905impl From<&'static str> for ElementId {
2906    fn from(name: &'static str) -> Self {
2907        ElementId::Name(name.into())
2908    }
2909}
2910
2911impl<'a> From<&'a FocusHandle> for ElementId {
2912    fn from(handle: &'a FocusHandle) -> Self {
2913        ElementId::FocusHandle(handle.id)
2914    }
2915}
2916
2917impl From<(&'static str, EntityId)> for ElementId {
2918    fn from((name, id): (&'static str, EntityId)) -> Self {
2919        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2920    }
2921}
2922
2923impl From<(&'static str, usize)> for ElementId {
2924    fn from((name, id): (&'static str, usize)) -> Self {
2925        ElementId::NamedInteger(name.into(), id)
2926    }
2927}
2928
2929impl From<(&'static str, u64)> for ElementId {
2930    fn from((name, id): (&'static str, u64)) -> Self {
2931        ElementId::NamedInteger(name.into(), id as usize)
2932    }
2933}