1use crate::{
   2    px, size, Action, AnyBox, AnyDrag, AnyView, AppContext, AsyncWindowContext, AvailableSpace,
   3    Bounds, BoxShadow, Context, Corners, DevicePixels, DispatchContext, DisplayId, Edges, Effect,
   4    Entity, EntityId, EventEmitter, FileDropEvent, FocusEvent, FontId, GlobalElementId, GlyphId,
   5    Hsla, ImageData, InputEvent, IsZero, KeyListener, KeyMatch, KeyMatcher, Keystroke, LayoutId,
   6    Model, ModelContext, Modifiers, MonochromeSprite, MouseButton, MouseDownEvent, MouseMoveEvent,
   7    MouseUpEvent, Path, Pixels, PlatformAtlas, PlatformDisplay, PlatformWindow, Point,
   8    PolychromeSprite, PromptLevel, Quad, Render, RenderGlyphParams, RenderImageParams,
   9    RenderSvgParams, ScaledPixels, SceneBuilder, Shadow, SharedString, Size, Style, SubscriberSet,
  10    Subscription, TaffyLayoutEngine, Task, Underline, UnderlineStyle, View, VisualContext,
  11    WeakView, WindowBounds, WindowOptions, SUBPIXEL_VARIANTS,
  12};
  13use anyhow::{anyhow, Result};
  14use collections::HashMap;
  15use derive_more::{Deref, DerefMut};
  16use futures::channel::oneshot;
  17use parking_lot::RwLock;
  18use slotmap::SlotMap;
  19use smallvec::SmallVec;
  20use std::{
  21    any::{Any, TypeId},
  22    borrow::{Borrow, BorrowMut, Cow},
  23    fmt::Debug,
  24    future::Future,
  25    hash::{Hash, Hasher},
  26    marker::PhantomData,
  27    mem,
  28    rc::Rc,
  29    sync::{
  30        atomic::{AtomicUsize, Ordering::SeqCst},
  31        Arc,
  32    },
  33};
  34use util::ResultExt;
  35
  36/// A global stacking order, which is created by stacking successive z-index values.
  37/// Each z-index will always be interpreted in the context of its parent z-index.
  38#[derive(Deref, DerefMut, Ord, PartialOrd, Eq, PartialEq, Clone, Default)]
  39pub(crate) struct StackingOrder(pub(crate) SmallVec<[u32; 16]>);
  40
  41/// Represents the two different phases when dispatching events.
  42#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  43pub enum DispatchPhase {
  44    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  45    /// invoked front to back and keyboard event listeners are invoked from the focused element
  46    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  47    /// registering event listeners.
  48    #[default]
  49    Bubble,
  50    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  51    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  52    /// is used for special purposes such as clearing the "pressed" state for click events. If
  53    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  54    /// outside of the immediate region may rely on detecting non-local events during this phase.
  55    Capture,
  56}
  57
  58type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
  59type AnyListener = Box<dyn Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static>;
  60type AnyKeyListener = Box<
  61    dyn Fn(
  62            &dyn Any,
  63            &[&DispatchContext],
  64            DispatchPhase,
  65            &mut WindowContext,
  66        ) -> Option<Box<dyn Action>>
  67        + 'static,
  68>;
  69type AnyFocusListener = Box<dyn Fn(&FocusEvent, &mut WindowContext) + 'static>;
  70
  71slotmap::new_key_type! { pub struct FocusId; }
  72
  73/// A handle which can be used to track and manipulate the focused element in a window.
  74pub struct FocusHandle {
  75    pub(crate) id: FocusId,
  76    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
  77}
  78
  79impl FocusHandle {
  80    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
  81        let id = handles.write().insert(AtomicUsize::new(1));
  82        Self {
  83            id,
  84            handles: handles.clone(),
  85        }
  86    }
  87
  88    pub(crate) fn for_id(
  89        id: FocusId,
  90        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
  91    ) -> Option<Self> {
  92        let lock = handles.read();
  93        let ref_count = lock.get(id)?;
  94        if ref_count.load(SeqCst) == 0 {
  95            None
  96        } else {
  97            ref_count.fetch_add(1, SeqCst);
  98            Some(Self {
  99                id,
 100                handles: handles.clone(),
 101            })
 102        }
 103    }
 104
 105    /// Obtains whether the element associated with this handle is currently focused.
 106    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 107        cx.window.focus == Some(self.id)
 108    }
 109
 110    /// Obtains whether the element associated with this handle contains the focused
 111    /// element or is itself focused.
 112    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 113        cx.focused()
 114            .map_or(false, |focused| self.contains(&focused, cx))
 115    }
 116
 117    /// Obtains whether the element associated with this handle is contained within the
 118    /// focused element or is itself focused.
 119    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 120        let focused = cx.focused();
 121        focused.map_or(false, |focused| focused.contains(self, cx))
 122    }
 123
 124    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 125    pub(crate) fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 126        let mut ancestor = Some(other.id);
 127        while let Some(ancestor_id) = ancestor {
 128            if self.id == ancestor_id {
 129                return true;
 130            } else {
 131                ancestor = cx.window.focus_parents_by_child.get(&ancestor_id).copied();
 132            }
 133        }
 134        false
 135    }
 136}
 137
 138impl Clone for FocusHandle {
 139    fn clone(&self) -> Self {
 140        Self::for_id(self.id, &self.handles).unwrap()
 141    }
 142}
 143
 144impl PartialEq for FocusHandle {
 145    fn eq(&self, other: &Self) -> bool {
 146        self.id == other.id
 147    }
 148}
 149
 150impl Eq for FocusHandle {}
 151
 152impl Drop for FocusHandle {
 153    fn drop(&mut self) {
 154        self.handles
 155            .read()
 156            .get(self.id)
 157            .unwrap()
 158            .fetch_sub(1, SeqCst);
 159    }
 160}
 161
 162// Holds the state for a specific window.
 163pub struct Window {
 164    pub(crate) handle: AnyWindowHandle,
 165    pub(crate) removed: bool,
 166    platform_window: Box<dyn PlatformWindow>,
 167    display_id: DisplayId,
 168    sprite_atlas: Arc<dyn PlatformAtlas>,
 169    rem_size: Pixels,
 170    content_size: Size<Pixels>,
 171    pub(crate) layout_engine: TaffyLayoutEngine,
 172    pub(crate) root_view: Option<AnyView>,
 173    pub(crate) element_id_stack: GlobalElementId,
 174    prev_frame_element_states: HashMap<GlobalElementId, AnyBox>,
 175    element_states: HashMap<GlobalElementId, AnyBox>,
 176    prev_frame_key_matchers: HashMap<GlobalElementId, KeyMatcher>,
 177    key_matchers: HashMap<GlobalElementId, KeyMatcher>,
 178    z_index_stack: StackingOrder,
 179    content_mask_stack: Vec<ContentMask<Pixels>>,
 180    element_offset_stack: Vec<Point<Pixels>>,
 181    mouse_listeners: HashMap<TypeId, Vec<(StackingOrder, AnyListener)>>,
 182    key_dispatch_stack: Vec<KeyDispatchStackFrame>,
 183    freeze_key_dispatch_stack: bool,
 184    focus_stack: Vec<FocusId>,
 185    focus_parents_by_child: HashMap<FocusId, FocusId>,
 186    pub(crate) focus_listeners: Vec<AnyFocusListener>,
 187    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 188    default_prevented: bool,
 189    mouse_position: Point<Pixels>,
 190    scale_factor: f32,
 191    bounds: WindowBounds,
 192    bounds_observers: SubscriberSet<(), AnyObserver>,
 193    active: bool,
 194    activation_observers: SubscriberSet<(), AnyObserver>,
 195    pub(crate) scene_builder: SceneBuilder,
 196    pub(crate) dirty: bool,
 197    pub(crate) last_blur: Option<Option<FocusId>>,
 198    pub(crate) focus: Option<FocusId>,
 199}
 200
 201impl Window {
 202    pub(crate) fn new(
 203        handle: AnyWindowHandle,
 204        options: WindowOptions,
 205        cx: &mut AppContext,
 206    ) -> Self {
 207        let platform_window = cx.platform.open_window(handle, options);
 208        let display_id = platform_window.display().id();
 209        let sprite_atlas = platform_window.sprite_atlas();
 210        let mouse_position = platform_window.mouse_position();
 211        let content_size = platform_window.content_size();
 212        let scale_factor = platform_window.scale_factor();
 213        let bounds = platform_window.bounds();
 214
 215        platform_window.on_resize(Box::new({
 216            let mut cx = cx.to_async();
 217            move |_, _| {
 218                handle
 219                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 220                    .log_err();
 221            }
 222        }));
 223        platform_window.on_moved(Box::new({
 224            let mut cx = cx.to_async();
 225            move || {
 226                handle
 227                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 228                    .log_err();
 229            }
 230        }));
 231        platform_window.on_active_status_change(Box::new({
 232            let mut cx = cx.to_async();
 233            move |active| {
 234                handle
 235                    .update(&mut cx, |_, cx| {
 236                        cx.window.active = active;
 237                        cx.window
 238                            .activation_observers
 239                            .clone()
 240                            .retain(&(), |callback| callback(cx));
 241                    })
 242                    .log_err();
 243            }
 244        }));
 245
 246        platform_window.on_input({
 247            let mut cx = cx.to_async();
 248            Box::new(move |event| {
 249                handle
 250                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 251                    .log_err()
 252                    .unwrap_or(true)
 253            })
 254        });
 255
 256        Window {
 257            handle,
 258            removed: false,
 259            platform_window,
 260            display_id,
 261            sprite_atlas,
 262            rem_size: px(16.),
 263            content_size,
 264            layout_engine: TaffyLayoutEngine::new(),
 265            root_view: None,
 266            element_id_stack: GlobalElementId::default(),
 267            prev_frame_element_states: HashMap::default(),
 268            element_states: HashMap::default(),
 269            prev_frame_key_matchers: HashMap::default(),
 270            key_matchers: HashMap::default(),
 271            z_index_stack: StackingOrder(SmallVec::new()),
 272            content_mask_stack: Vec::new(),
 273            element_offset_stack: Vec::new(),
 274            mouse_listeners: HashMap::default(),
 275            key_dispatch_stack: Vec::new(),
 276            freeze_key_dispatch_stack: false,
 277            focus_stack: Vec::new(),
 278            focus_parents_by_child: HashMap::default(),
 279            focus_listeners: Vec::new(),
 280            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 281            default_prevented: true,
 282            mouse_position,
 283            scale_factor,
 284            bounds,
 285            bounds_observers: SubscriberSet::new(),
 286            active: false,
 287            activation_observers: SubscriberSet::new(),
 288            scene_builder: SceneBuilder::new(),
 289            dirty: true,
 290            last_blur: None,
 291            focus: None,
 292        }
 293    }
 294}
 295
 296/// When constructing the element tree, we maintain a stack of key dispatch frames until we
 297/// find the focused element. We interleave key listeners with dispatch contexts so we can use the
 298/// contexts when matching key events against the keymap.
 299enum KeyDispatchStackFrame {
 300    Listener {
 301        event_type: TypeId,
 302        listener: AnyKeyListener,
 303    },
 304    Context(DispatchContext),
 305}
 306
 307/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 308/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 309/// to leave room to support more complex shapes in the future.
 310#[derive(Clone, Debug, Default, PartialEq, Eq)]
 311#[repr(C)]
 312pub struct ContentMask<P: Clone + Default + Debug> {
 313    pub bounds: Bounds<P>,
 314}
 315
 316impl ContentMask<Pixels> {
 317    /// Scale the content mask's pixel units by the given scaling factor.
 318    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 319        ContentMask {
 320            bounds: self.bounds.scale(factor),
 321        }
 322    }
 323
 324    /// Intersect the content mask with the given content mask.
 325    pub fn intersect(&self, other: &Self) -> Self {
 326        let bounds = self.bounds.intersect(&other.bounds);
 327        ContentMask { bounds }
 328    }
 329}
 330
 331/// Provides access to application state in the context of a single window. Derefs
 332/// to an `AppContext`, so you can also pass a `WindowContext` to any method that takes
 333/// an `AppContext` and call any `AppContext` methods.
 334pub struct WindowContext<'a> {
 335    pub(crate) app: &'a mut AppContext,
 336    pub(crate) window: &'a mut Window,
 337}
 338
 339impl<'a> WindowContext<'a> {
 340    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 341        Self { app, window }
 342    }
 343
 344    /// Obtain a handle to the window that belongs to this context.
 345    pub fn window_handle(&self) -> AnyWindowHandle {
 346        self.window.handle
 347    }
 348
 349    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 350    pub fn notify(&mut self) {
 351        self.window.dirty = true;
 352    }
 353
 354    /// Close this window.
 355    pub fn remove_window(&mut self) {
 356        self.window.removed = true;
 357    }
 358
 359    /// Obtain a new `FocusHandle`, which allows you to track and manipulate the keyboard focus
 360    /// for elements rendered within this window.
 361    pub fn focus_handle(&mut self) -> FocusHandle {
 362        FocusHandle::new(&self.window.focus_handles)
 363    }
 364
 365    /// Obtain the currently focused `FocusHandle`. If no elements are focused, returns `None`.
 366    pub fn focused(&self) -> Option<FocusHandle> {
 367        self.window
 368            .focus
 369            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 370    }
 371
 372    /// Move focus to the element associated with the given `FocusHandle`.
 373    pub fn focus(&mut self, handle: &FocusHandle) {
 374        if self.window.last_blur.is_none() {
 375            self.window.last_blur = Some(self.window.focus);
 376        }
 377
 378        self.window.focus = Some(handle.id);
 379        self.app.push_effect(Effect::FocusChanged {
 380            window_handle: self.window.handle,
 381            focused: Some(handle.id),
 382        });
 383        self.notify();
 384    }
 385
 386    /// Remove focus from all elements within this context's window.
 387    pub fn blur(&mut self) {
 388        if self.window.last_blur.is_none() {
 389            self.window.last_blur = Some(self.window.focus);
 390        }
 391
 392        self.window.focus = None;
 393        self.app.push_effect(Effect::FocusChanged {
 394            window_handle: self.window.handle,
 395            focused: None,
 396        });
 397        self.notify();
 398    }
 399
 400    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 401    /// that are currently on the stack to be returned to the app.
 402    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 403        let handle = self.window.handle;
 404        self.app.defer(move |cx| {
 405            handle.update(cx, |_, cx| f(cx)).ok();
 406        });
 407    }
 408
 409    pub fn subscribe<Emitter, E>(
 410        &mut self,
 411        entity: &E,
 412        mut on_event: impl FnMut(E, &Emitter::Event, &mut WindowContext<'_>) + 'static,
 413    ) -> Subscription
 414    where
 415        Emitter: EventEmitter,
 416        E: Entity<Emitter>,
 417    {
 418        let entity_id = entity.entity_id();
 419        let entity = entity.downgrade();
 420        let window_handle = self.window.handle;
 421        self.app.event_listeners.insert(
 422            entity_id,
 423            Box::new(move |event, cx| {
 424                window_handle
 425                    .update(cx, |_, cx| {
 426                        if let Some(handle) = E::upgrade_from(&entity) {
 427                            let event = event.downcast_ref().expect("invalid event type");
 428                            on_event(handle, event, cx);
 429                            true
 430                        } else {
 431                            false
 432                        }
 433                    })
 434                    .unwrap_or(false)
 435            }),
 436        )
 437    }
 438
 439    /// Create an `AsyncWindowContext`, which has a static lifetime and can be held across
 440    /// await points in async code.
 441    pub fn to_async(&self) -> AsyncWindowContext {
 442        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 443    }
 444
 445    /// Schedule the given closure to be run directly after the current frame is rendered.
 446    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 447        let f = Box::new(f);
 448        let display_id = self.window.display_id;
 449
 450        if let Some(callbacks) = self.next_frame_callbacks.get_mut(&display_id) {
 451            callbacks.push(f);
 452            // If there was already a callback, it means that we already scheduled a frame.
 453            if callbacks.len() > 1 {
 454                return;
 455            }
 456        } else {
 457            let mut async_cx = self.to_async();
 458            self.next_frame_callbacks.insert(display_id, vec![f]);
 459            self.platform.set_display_link_output_callback(
 460                display_id,
 461                Box::new(move |_current_time, _output_time| {
 462                    let _ = async_cx.update(|_, cx| {
 463                        let callbacks = cx
 464                            .next_frame_callbacks
 465                            .get_mut(&display_id)
 466                            .unwrap()
 467                            .drain(..)
 468                            .collect::<Vec<_>>();
 469                        for callback in callbacks {
 470                            callback(cx);
 471                        }
 472
 473                        if cx.next_frame_callbacks.get(&display_id).unwrap().is_empty() {
 474                            cx.platform.stop_display_link(display_id);
 475                        }
 476                    });
 477                }),
 478            );
 479        }
 480
 481        self.platform.start_display_link(display_id);
 482    }
 483
 484    /// Spawn the future returned by the given closure on the application thread pool.
 485    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 486    /// use within your future.
 487    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 488    where
 489        R: 'static,
 490        Fut: Future<Output = R> + 'static,
 491    {
 492        self.app
 493            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 494    }
 495
 496    /// Update the global of the given type. The given closure is given simultaneous mutable
 497    /// access both to the global and the context.
 498    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 499    where
 500        G: 'static,
 501    {
 502        let mut global = self.app.lease_global::<G>();
 503        let result = f(&mut global, self);
 504        self.app.end_global_lease(global);
 505        result
 506    }
 507
 508    /// Add a node to the layout tree for the current frame. Takes the `Style` of the element for which
 509    /// layout is being requested, along with the layout ids of any children. This method is called during
 510    /// calls to the `Element::layout` trait method and enables any element to participate in layout.
 511    pub fn request_layout(
 512        &mut self,
 513        style: &Style,
 514        children: impl IntoIterator<Item = LayoutId>,
 515    ) -> LayoutId {
 516        self.app.layout_id_buffer.clear();
 517        self.app.layout_id_buffer.extend(children.into_iter());
 518        let rem_size = self.rem_size();
 519
 520        self.window
 521            .layout_engine
 522            .request_layout(style, rem_size, &self.app.layout_id_buffer)
 523    }
 524
 525    /// Add a node to the layout tree for the current frame. Instead of taking a `Style` and children,
 526    /// this variant takes a function that is invoked during layout so you can use arbitrary logic to
 527    /// determine the element's size. One place this is used internally is when measuring text.
 528    ///
 529    /// The given closure is invoked at layout time with the known dimensions and available space and
 530    /// returns a `Size`.
 531    pub fn request_measured_layout<
 532        F: Fn(Size<Option<Pixels>>, Size<AvailableSpace>) -> Size<Pixels> + Send + Sync + 'static,
 533    >(
 534        &mut self,
 535        style: Style,
 536        rem_size: Pixels,
 537        measure: F,
 538    ) -> LayoutId {
 539        self.window
 540            .layout_engine
 541            .request_measured_layout(style, rem_size, measure)
 542    }
 543
 544    /// Obtain the bounds computed for the given LayoutId relative to the window. This method should not
 545    /// be invoked until the paint phase begins, and will usually be invoked by GPUI itself automatically
 546    /// in order to pass your element its `Bounds` automatically.
 547    pub fn layout_bounds(&mut self, layout_id: LayoutId) -> Bounds<Pixels> {
 548        let mut bounds = self
 549            .window
 550            .layout_engine
 551            .layout_bounds(layout_id)
 552            .map(Into::into);
 553        bounds.origin += self.element_offset();
 554        bounds
 555    }
 556
 557    fn window_bounds_changed(&mut self) {
 558        self.window.scale_factor = self.window.platform_window.scale_factor();
 559        self.window.content_size = self.window.platform_window.content_size();
 560        self.window.bounds = self.window.platform_window.bounds();
 561        self.window.display_id = self.window.platform_window.display().id();
 562        self.window.dirty = true;
 563
 564        self.window
 565            .bounds_observers
 566            .clone()
 567            .retain(&(), |callback| callback(self));
 568    }
 569
 570    pub fn window_bounds(&self) -> WindowBounds {
 571        self.window.bounds
 572    }
 573
 574    pub fn is_window_active(&self) -> bool {
 575        self.window.active
 576    }
 577
 578    pub fn zoom_window(&self) {
 579        self.window.platform_window.zoom();
 580    }
 581
 582    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 583        self.platform
 584            .displays()
 585            .into_iter()
 586            .find(|display| display.id() == self.window.display_id)
 587    }
 588
 589    /// The scale factor of the display associated with the window. For example, it could
 590    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 591    /// be rendered as two pixels on screen.
 592    pub fn scale_factor(&self) -> f32 {
 593        self.window.scale_factor
 594    }
 595
 596    /// The size of an em for the base font of the application. Adjusting this value allows the
 597    /// UI to scale, just like zooming a web page.
 598    pub fn rem_size(&self) -> Pixels {
 599        self.window.rem_size
 600    }
 601
 602    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 603    /// UI to scale, just like zooming a web page.
 604    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 605        self.window.rem_size = rem_size.into();
 606    }
 607
 608    /// The line height associated with the current text style.
 609    pub fn line_height(&self) -> Pixels {
 610        let rem_size = self.rem_size();
 611        let text_style = self.text_style();
 612        text_style
 613            .line_height
 614            .to_pixels(text_style.font_size.into(), rem_size)
 615    }
 616
 617    /// Call to prevent the default action of an event. Currently only used to prevent
 618    /// parent elements from becoming focused on mouse down.
 619    pub fn prevent_default(&mut self) {
 620        self.window.default_prevented = true;
 621    }
 622
 623    /// Obtain whether default has been prevented for the event currently being dispatched.
 624    pub fn default_prevented(&self) -> bool {
 625        self.window.default_prevented
 626    }
 627
 628    /// Register a mouse event listener on the window for the current frame. The type of event
 629    /// is determined by the first parameter of the given listener. When the next frame is rendered
 630    /// the listener will be cleared.
 631    ///
 632    /// This is a fairly low-level method, so prefer using event handlers on elements unless you have
 633    /// a specific need to register a global listener.
 634    pub fn on_mouse_event<Event: 'static>(
 635        &mut self,
 636        handler: impl Fn(&Event, DispatchPhase, &mut WindowContext) + 'static,
 637    ) {
 638        let order = self.window.z_index_stack.clone();
 639        self.window
 640            .mouse_listeners
 641            .entry(TypeId::of::<Event>())
 642            .or_default()
 643            .push((
 644                order,
 645                Box::new(move |event: &dyn Any, phase, cx| {
 646                    handler(event.downcast_ref().unwrap(), phase, cx)
 647                }),
 648            ))
 649    }
 650
 651    /// The position of the mouse relative to the window.
 652    pub fn mouse_position(&self) -> Point<Pixels> {
 653        self.window.mouse_position
 654    }
 655
 656    /// Called during painting to invoke the given closure in a new stacking context. The given
 657    /// z-index is interpreted relative to the previous call to `stack`.
 658    pub fn stack<R>(&mut self, z_index: u32, f: impl FnOnce(&mut Self) -> R) -> R {
 659        self.window.z_index_stack.push(z_index);
 660        let result = f(self);
 661        self.window.z_index_stack.pop();
 662        result
 663    }
 664
 665    /// Paint one or more drop shadows into the scene for the current frame at the current z-index.
 666    pub fn paint_shadows(
 667        &mut self,
 668        bounds: Bounds<Pixels>,
 669        corner_radii: Corners<Pixels>,
 670        shadows: &[BoxShadow],
 671    ) {
 672        let scale_factor = self.scale_factor();
 673        let content_mask = self.content_mask();
 674        let window = &mut *self.window;
 675        for shadow in shadows {
 676            let mut shadow_bounds = bounds;
 677            shadow_bounds.origin += shadow.offset;
 678            shadow_bounds.dilate(shadow.spread_radius);
 679            window.scene_builder.insert(
 680                &window.z_index_stack,
 681                Shadow {
 682                    order: 0,
 683                    bounds: shadow_bounds.scale(scale_factor),
 684                    content_mask: content_mask.scale(scale_factor),
 685                    corner_radii: corner_radii.scale(scale_factor),
 686                    color: shadow.color,
 687                    blur_radius: shadow.blur_radius.scale(scale_factor),
 688                },
 689            );
 690        }
 691    }
 692
 693    /// Paint one or more quads into the scene for the current frame at the current stacking context.
 694    /// Quads are colored rectangular regions with an optional background, border, and corner radius.
 695    pub fn paint_quad(
 696        &mut self,
 697        bounds: Bounds<Pixels>,
 698        corner_radii: Corners<Pixels>,
 699        background: impl Into<Hsla>,
 700        border_widths: Edges<Pixels>,
 701        border_color: impl Into<Hsla>,
 702    ) {
 703        let scale_factor = self.scale_factor();
 704        let content_mask = self.content_mask();
 705
 706        let window = &mut *self.window;
 707        window.scene_builder.insert(
 708            &window.z_index_stack,
 709            Quad {
 710                order: 0,
 711                bounds: bounds.scale(scale_factor),
 712                content_mask: content_mask.scale(scale_factor),
 713                background: background.into(),
 714                border_color: border_color.into(),
 715                corner_radii: corner_radii.scale(scale_factor),
 716                border_widths: border_widths.scale(scale_factor),
 717            },
 718        );
 719    }
 720
 721    /// Paint the given `Path` into the scene for the current frame at the current z-index.
 722    pub fn paint_path(&mut self, mut path: Path<Pixels>, color: impl Into<Hsla>) {
 723        let scale_factor = self.scale_factor();
 724        let content_mask = self.content_mask();
 725        path.content_mask = content_mask;
 726        path.color = color.into();
 727        let window = &mut *self.window;
 728        window
 729            .scene_builder
 730            .insert(&window.z_index_stack, path.scale(scale_factor));
 731    }
 732
 733    /// Paint an underline into the scene for the current frame at the current z-index.
 734    pub fn paint_underline(
 735        &mut self,
 736        origin: Point<Pixels>,
 737        width: Pixels,
 738        style: &UnderlineStyle,
 739    ) -> Result<()> {
 740        let scale_factor = self.scale_factor();
 741        let height = if style.wavy {
 742            style.thickness * 3.
 743        } else {
 744            style.thickness
 745        };
 746        let bounds = Bounds {
 747            origin,
 748            size: size(width, height),
 749        };
 750        let content_mask = self.content_mask();
 751        let window = &mut *self.window;
 752        window.scene_builder.insert(
 753            &window.z_index_stack,
 754            Underline {
 755                order: 0,
 756                bounds: bounds.scale(scale_factor),
 757                content_mask: content_mask.scale(scale_factor),
 758                thickness: style.thickness.scale(scale_factor),
 759                color: style.color.unwrap_or_default(),
 760                wavy: style.wavy,
 761            },
 762        );
 763        Ok(())
 764    }
 765
 766    /// Paint a monochrome (non-emoji) glyph into the scene for the current frame at the current z-index.
 767    pub fn paint_glyph(
 768        &mut self,
 769        origin: Point<Pixels>,
 770        font_id: FontId,
 771        glyph_id: GlyphId,
 772        font_size: Pixels,
 773        color: Hsla,
 774    ) -> Result<()> {
 775        let scale_factor = self.scale_factor();
 776        let glyph_origin = origin.scale(scale_factor);
 777        let subpixel_variant = Point {
 778            x: (glyph_origin.x.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
 779            y: (glyph_origin.y.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
 780        };
 781        let params = RenderGlyphParams {
 782            font_id,
 783            glyph_id,
 784            font_size,
 785            subpixel_variant,
 786            scale_factor,
 787            is_emoji: false,
 788        };
 789
 790        let raster_bounds = self.text_system().raster_bounds(&params)?;
 791        if !raster_bounds.is_zero() {
 792            let tile =
 793                self.window
 794                    .sprite_atlas
 795                    .get_or_insert_with(&params.clone().into(), &mut || {
 796                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
 797                        Ok((size, Cow::Owned(bytes)))
 798                    })?;
 799            let bounds = Bounds {
 800                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
 801                size: tile.bounds.size.map(Into::into),
 802            };
 803            let content_mask = self.content_mask().scale(scale_factor);
 804            let window = &mut *self.window;
 805            window.scene_builder.insert(
 806                &window.z_index_stack,
 807                MonochromeSprite {
 808                    order: 0,
 809                    bounds,
 810                    content_mask,
 811                    color,
 812                    tile,
 813                },
 814            );
 815        }
 816        Ok(())
 817    }
 818
 819    /// Paint an emoji glyph into the scene for the current frame at the current z-index.
 820    pub fn paint_emoji(
 821        &mut self,
 822        origin: Point<Pixels>,
 823        font_id: FontId,
 824        glyph_id: GlyphId,
 825        font_size: Pixels,
 826    ) -> Result<()> {
 827        let scale_factor = self.scale_factor();
 828        let glyph_origin = origin.scale(scale_factor);
 829        let params = RenderGlyphParams {
 830            font_id,
 831            glyph_id,
 832            font_size,
 833            // We don't render emojis with subpixel variants.
 834            subpixel_variant: Default::default(),
 835            scale_factor,
 836            is_emoji: true,
 837        };
 838
 839        let raster_bounds = self.text_system().raster_bounds(&params)?;
 840        if !raster_bounds.is_zero() {
 841            let tile =
 842                self.window
 843                    .sprite_atlas
 844                    .get_or_insert_with(&params.clone().into(), &mut || {
 845                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
 846                        Ok((size, Cow::Owned(bytes)))
 847                    })?;
 848            let bounds = Bounds {
 849                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
 850                size: tile.bounds.size.map(Into::into),
 851            };
 852            let content_mask = self.content_mask().scale(scale_factor);
 853            let window = &mut *self.window;
 854
 855            window.scene_builder.insert(
 856                &window.z_index_stack,
 857                PolychromeSprite {
 858                    order: 0,
 859                    bounds,
 860                    corner_radii: Default::default(),
 861                    content_mask,
 862                    tile,
 863                    grayscale: false,
 864                },
 865            );
 866        }
 867        Ok(())
 868    }
 869
 870    /// Paint a monochrome SVG into the scene for the current frame at the current stacking context.
 871    pub fn paint_svg(
 872        &mut self,
 873        bounds: Bounds<Pixels>,
 874        path: SharedString,
 875        color: Hsla,
 876    ) -> Result<()> {
 877        let scale_factor = self.scale_factor();
 878        let bounds = bounds.scale(scale_factor);
 879        // Render the SVG at twice the size to get a higher quality result.
 880        let params = RenderSvgParams {
 881            path,
 882            size: bounds
 883                .size
 884                .map(|pixels| DevicePixels::from((pixels.0 * 2.).ceil() as i32)),
 885        };
 886
 887        let tile =
 888            self.window
 889                .sprite_atlas
 890                .get_or_insert_with(&params.clone().into(), &mut || {
 891                    let bytes = self.svg_renderer.render(&params)?;
 892                    Ok((params.size, Cow::Owned(bytes)))
 893                })?;
 894        let content_mask = self.content_mask().scale(scale_factor);
 895
 896        let window = &mut *self.window;
 897        window.scene_builder.insert(
 898            &window.z_index_stack,
 899            MonochromeSprite {
 900                order: 0,
 901                bounds,
 902                content_mask,
 903                color,
 904                tile,
 905            },
 906        );
 907
 908        Ok(())
 909    }
 910
 911    /// Paint an image into the scene for the current frame at the current z-index.
 912    pub fn paint_image(
 913        &mut self,
 914        bounds: Bounds<Pixels>,
 915        corner_radii: Corners<Pixels>,
 916        data: Arc<ImageData>,
 917        grayscale: bool,
 918    ) -> Result<()> {
 919        let scale_factor = self.scale_factor();
 920        let bounds = bounds.scale(scale_factor);
 921        let params = RenderImageParams { image_id: data.id };
 922
 923        let tile = self
 924            .window
 925            .sprite_atlas
 926            .get_or_insert_with(&params.clone().into(), &mut || {
 927                Ok((data.size(), Cow::Borrowed(data.as_bytes())))
 928            })?;
 929        let content_mask = self.content_mask().scale(scale_factor);
 930        let corner_radii = corner_radii.scale(scale_factor);
 931
 932        let window = &mut *self.window;
 933        window.scene_builder.insert(
 934            &window.z_index_stack,
 935            PolychromeSprite {
 936                order: 0,
 937                bounds,
 938                content_mask,
 939                corner_radii,
 940                tile,
 941                grayscale,
 942            },
 943        );
 944        Ok(())
 945    }
 946
 947    /// Draw pixels to the display for this window based on the contents of its scene.
 948    pub(crate) fn draw(&mut self) {
 949        let root_view = self.window.root_view.take().unwrap();
 950
 951        self.start_frame();
 952
 953        self.stack(0, |cx| {
 954            let available_space = cx.window.content_size.map(Into::into);
 955            root_view.draw(available_space, cx);
 956        });
 957
 958        if let Some(active_drag) = self.app.active_drag.take() {
 959            self.stack(1, |cx| {
 960                let offset = cx.mouse_position() - active_drag.cursor_offset;
 961                cx.with_element_offset(Some(offset), |cx| {
 962                    let available_space =
 963                        size(AvailableSpace::MinContent, AvailableSpace::MinContent);
 964                    active_drag.view.draw(available_space, cx);
 965                    cx.active_drag = Some(active_drag);
 966                });
 967            });
 968        }
 969
 970        self.window.root_view = Some(root_view);
 971        let scene = self.window.scene_builder.build();
 972
 973        self.window.platform_window.draw(scene);
 974        self.window.dirty = false;
 975    }
 976
 977    fn start_frame(&mut self) {
 978        self.text_system().start_frame();
 979
 980        let window = &mut *self.window;
 981
 982        // Move the current frame element states to the previous frame.
 983        // The new empty element states map will be populated for any element states we
 984        // reference during the upcoming frame.
 985        mem::swap(
 986            &mut window.element_states,
 987            &mut window.prev_frame_element_states,
 988        );
 989        window.element_states.clear();
 990
 991        // Make the current key matchers the previous, and then clear the current.
 992        // An empty key matcher map will be created for every identified element in the
 993        // upcoming frame.
 994        mem::swap(
 995            &mut window.key_matchers,
 996            &mut window.prev_frame_key_matchers,
 997        );
 998        window.key_matchers.clear();
 999
1000        // Clear mouse event listeners, because elements add new element listeners
1001        // when the upcoming frame is painted.
1002        window.mouse_listeners.values_mut().for_each(Vec::clear);
1003
1004        // Clear focus state, because we determine what is focused when the new elements
1005        // in the upcoming frame are initialized.
1006        window.focus_listeners.clear();
1007        window.key_dispatch_stack.clear();
1008        window.focus_parents_by_child.clear();
1009        window.freeze_key_dispatch_stack = false;
1010    }
1011
1012    /// Dispatch a mouse or keyboard event on the window.
1013    fn dispatch_event(&mut self, event: InputEvent) -> bool {
1014        let event = match event {
1015            // Track the mouse position with our own state, since accessing the platform
1016            // API for the mouse position can only occur on the main thread.
1017            InputEvent::MouseMove(mouse_move) => {
1018                self.window.mouse_position = mouse_move.position;
1019                InputEvent::MouseMove(mouse_move)
1020            }
1021            // Translate dragging and dropping of external files from the operating system
1022            // to internal drag and drop events.
1023            InputEvent::FileDrop(file_drop) => match file_drop {
1024                FileDropEvent::Entered { position, files } => {
1025                    self.window.mouse_position = position;
1026                    if self.active_drag.is_none() {
1027                        self.active_drag = Some(AnyDrag {
1028                            view: self.build_view(|_| files).into(),
1029                            cursor_offset: position,
1030                        });
1031                    }
1032                    InputEvent::MouseDown(MouseDownEvent {
1033                        position,
1034                        button: MouseButton::Left,
1035                        click_count: 1,
1036                        modifiers: Modifiers::default(),
1037                    })
1038                }
1039                FileDropEvent::Pending { position } => {
1040                    self.window.mouse_position = position;
1041                    InputEvent::MouseMove(MouseMoveEvent {
1042                        position,
1043                        pressed_button: Some(MouseButton::Left),
1044                        modifiers: Modifiers::default(),
1045                    })
1046                }
1047                FileDropEvent::Submit { position } => {
1048                    self.window.mouse_position = position;
1049                    InputEvent::MouseUp(MouseUpEvent {
1050                        button: MouseButton::Left,
1051                        position,
1052                        modifiers: Modifiers::default(),
1053                        click_count: 1,
1054                    })
1055                }
1056                FileDropEvent::Exited => InputEvent::MouseUp(MouseUpEvent {
1057                    button: MouseButton::Left,
1058                    position: Point::default(),
1059                    modifiers: Modifiers::default(),
1060                    click_count: 1,
1061                }),
1062            },
1063            _ => event,
1064        };
1065
1066        if let Some(any_mouse_event) = event.mouse_event() {
1067            // Handlers may set this to false by calling `stop_propagation`
1068            self.app.propagate_event = true;
1069            self.window.default_prevented = false;
1070
1071            if let Some(mut handlers) = self
1072                .window
1073                .mouse_listeners
1074                .remove(&any_mouse_event.type_id())
1075            {
1076                // Because handlers may add other handlers, we sort every time.
1077                handlers.sort_by(|(a, _), (b, _)| a.cmp(b));
1078
1079                // Capture phase, events bubble from back to front. Handlers for this phase are used for
1080                // special purposes, such as detecting events outside of a given Bounds.
1081                for (_, handler) in &handlers {
1082                    handler(any_mouse_event, DispatchPhase::Capture, self);
1083                    if !self.app.propagate_event {
1084                        break;
1085                    }
1086                }
1087
1088                // Bubble phase, where most normal handlers do their work.
1089                if self.app.propagate_event {
1090                    for (_, handler) in handlers.iter().rev() {
1091                        handler(any_mouse_event, DispatchPhase::Bubble, self);
1092                        if !self.app.propagate_event {
1093                            break;
1094                        }
1095                    }
1096                }
1097
1098                if self.app.propagate_event
1099                    && any_mouse_event.downcast_ref::<MouseUpEvent>().is_some()
1100                {
1101                    self.active_drag = None;
1102                }
1103
1104                // Just in case any handlers added new handlers, which is weird, but possible.
1105                handlers.extend(
1106                    self.window
1107                        .mouse_listeners
1108                        .get_mut(&any_mouse_event.type_id())
1109                        .into_iter()
1110                        .flat_map(|handlers| handlers.drain(..)),
1111                );
1112                self.window
1113                    .mouse_listeners
1114                    .insert(any_mouse_event.type_id(), handlers);
1115            }
1116        } else if let Some(any_key_event) = event.keyboard_event() {
1117            let key_dispatch_stack = mem::take(&mut self.window.key_dispatch_stack);
1118            let key_event_type = any_key_event.type_id();
1119            let mut context_stack = SmallVec::<[&DispatchContext; 16]>::new();
1120
1121            for (ix, frame) in key_dispatch_stack.iter().enumerate() {
1122                match frame {
1123                    KeyDispatchStackFrame::Listener {
1124                        event_type,
1125                        listener,
1126                    } => {
1127                        if key_event_type == *event_type {
1128                            if let Some(action) = listener(
1129                                any_key_event,
1130                                &context_stack,
1131                                DispatchPhase::Capture,
1132                                self,
1133                            ) {
1134                                self.dispatch_action(action, &key_dispatch_stack[..ix]);
1135                            }
1136                            if !self.app.propagate_event {
1137                                break;
1138                            }
1139                        }
1140                    }
1141                    KeyDispatchStackFrame::Context(context) => {
1142                        context_stack.push(&context);
1143                    }
1144                }
1145            }
1146
1147            if self.app.propagate_event {
1148                for (ix, frame) in key_dispatch_stack.iter().enumerate().rev() {
1149                    match frame {
1150                        KeyDispatchStackFrame::Listener {
1151                            event_type,
1152                            listener,
1153                        } => {
1154                            if key_event_type == *event_type {
1155                                if let Some(action) = listener(
1156                                    any_key_event,
1157                                    &context_stack,
1158                                    DispatchPhase::Bubble,
1159                                    self,
1160                                ) {
1161                                    self.dispatch_action(action, &key_dispatch_stack[..ix]);
1162                                }
1163
1164                                if !self.app.propagate_event {
1165                                    break;
1166                                }
1167                            }
1168                        }
1169                        KeyDispatchStackFrame::Context(_) => {
1170                            context_stack.pop();
1171                        }
1172                    }
1173                }
1174            }
1175
1176            drop(context_stack);
1177            self.window.key_dispatch_stack = key_dispatch_stack;
1178        }
1179
1180        true
1181    }
1182
1183    /// Attempt to map a keystroke to an action based on the keymap.
1184    pub fn match_keystroke(
1185        &mut self,
1186        element_id: &GlobalElementId,
1187        keystroke: &Keystroke,
1188        context_stack: &[&DispatchContext],
1189    ) -> KeyMatch {
1190        let key_match = self
1191            .window
1192            .key_matchers
1193            .get_mut(element_id)
1194            .unwrap()
1195            .match_keystroke(keystroke, context_stack);
1196
1197        if key_match.is_some() {
1198            for matcher in self.window.key_matchers.values_mut() {
1199                matcher.clear_pending();
1200            }
1201        }
1202
1203        key_match
1204    }
1205
1206    /// Register the given handler to be invoked whenever the global of the given type
1207    /// is updated.
1208    pub fn observe_global<G: 'static>(
1209        &mut self,
1210        f: impl Fn(&mut WindowContext<'_>) + 'static,
1211    ) -> Subscription {
1212        let window_handle = self.window.handle;
1213        self.global_observers.insert(
1214            TypeId::of::<G>(),
1215            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1216        )
1217    }
1218
1219    pub fn activate_window(&self) {
1220        self.window.platform_window.activate();
1221    }
1222
1223    pub fn prompt(
1224        &self,
1225        level: PromptLevel,
1226        msg: &str,
1227        answers: &[&str],
1228    ) -> oneshot::Receiver<usize> {
1229        self.window.platform_window.prompt(level, msg, answers)
1230    }
1231
1232    fn dispatch_action(
1233        &mut self,
1234        action: Box<dyn Action>,
1235        dispatch_stack: &[KeyDispatchStackFrame],
1236    ) {
1237        let action_type = action.as_any().type_id();
1238
1239        if let Some(mut global_listeners) = self.app.global_action_listeners.remove(&action_type) {
1240            for listener in &global_listeners {
1241                listener(action.as_ref(), DispatchPhase::Capture, self);
1242                if !self.app.propagate_event {
1243                    break;
1244                }
1245            }
1246            global_listeners.extend(
1247                self.global_action_listeners
1248                    .remove(&action_type)
1249                    .unwrap_or_default(),
1250            );
1251            self.global_action_listeners
1252                .insert(action_type, global_listeners);
1253        }
1254
1255        if self.app.propagate_event {
1256            for stack_frame in dispatch_stack {
1257                if let KeyDispatchStackFrame::Listener {
1258                    event_type,
1259                    listener,
1260                } = stack_frame
1261                {
1262                    if action_type == *event_type {
1263                        listener(action.as_any(), &[], DispatchPhase::Capture, self);
1264                        if !self.app.propagate_event {
1265                            break;
1266                        }
1267                    }
1268                }
1269            }
1270        }
1271
1272        if self.app.propagate_event {
1273            for stack_frame in dispatch_stack.iter().rev() {
1274                if let KeyDispatchStackFrame::Listener {
1275                    event_type,
1276                    listener,
1277                } = stack_frame
1278                {
1279                    if action_type == *event_type {
1280                        listener(action.as_any(), &[], DispatchPhase::Bubble, self);
1281                        if !self.app.propagate_event {
1282                            break;
1283                        }
1284                    }
1285                }
1286            }
1287        }
1288
1289        if self.app.propagate_event {
1290            if let Some(mut global_listeners) =
1291                self.app.global_action_listeners.remove(&action_type)
1292            {
1293                for listener in global_listeners.iter().rev() {
1294                    listener(action.as_ref(), DispatchPhase::Bubble, self);
1295                    if !self.app.propagate_event {
1296                        break;
1297                    }
1298                }
1299                global_listeners.extend(
1300                    self.global_action_listeners
1301                        .remove(&action_type)
1302                        .unwrap_or_default(),
1303                );
1304                self.global_action_listeners
1305                    .insert(action_type, global_listeners);
1306            }
1307        }
1308    }
1309}
1310
1311impl Context for WindowContext<'_> {
1312    type Result<T> = T;
1313
1314    fn build_model<T>(
1315        &mut self,
1316        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
1317    ) -> Model<T>
1318    where
1319        T: 'static,
1320    {
1321        let slot = self.app.entities.reserve();
1322        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1323        self.entities.insert(slot, model)
1324    }
1325
1326    fn update_model<T: 'static, R>(
1327        &mut self,
1328        model: &Model<T>,
1329        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1330    ) -> R {
1331        let mut entity = self.entities.lease(model);
1332        let result = update(
1333            &mut *entity,
1334            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1335        );
1336        self.entities.end_lease(entity);
1337        result
1338    }
1339
1340    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1341    where
1342        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1343    {
1344        if window == self.window.handle {
1345            let root_view = self.window.root_view.clone().unwrap();
1346            Ok(update(root_view, self))
1347        } else {
1348            window.update(self.app, update)
1349        }
1350    }
1351}
1352
1353impl VisualContext for WindowContext<'_> {
1354    fn build_view<V>(
1355        &mut self,
1356        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1357    ) -> Self::Result<View<V>>
1358    where
1359        V: 'static,
1360    {
1361        let slot = self.app.entities.reserve();
1362        let view = View {
1363            model: slot.clone(),
1364        };
1365        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1366        let entity = build_view_state(&mut cx);
1367        self.entities.insert(slot, entity);
1368        view
1369    }
1370
1371    /// Update the given view. Prefer calling `View::update` instead, which calls this method.
1372    fn update_view<T: 'static, R>(
1373        &mut self,
1374        view: &View<T>,
1375        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1376    ) -> Self::Result<R> {
1377        let mut lease = self.app.entities.lease(&view.model);
1378        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1379        let result = update(&mut *lease, &mut cx);
1380        cx.app.entities.end_lease(lease);
1381        result
1382    }
1383
1384    fn replace_root_view<V>(
1385        &mut self,
1386        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1387    ) -> Self::Result<View<V>>
1388    where
1389        V: Render,
1390    {
1391        let slot = self.app.entities.reserve();
1392        let view = View {
1393            model: slot.clone(),
1394        };
1395        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1396        let entity = build_view(&mut cx);
1397        self.entities.insert(slot, entity);
1398        self.window.root_view = Some(view.clone().into());
1399        view
1400    }
1401}
1402
1403impl<'a> std::ops::Deref for WindowContext<'a> {
1404    type Target = AppContext;
1405
1406    fn deref(&self) -> &Self::Target {
1407        &self.app
1408    }
1409}
1410
1411impl<'a> std::ops::DerefMut for WindowContext<'a> {
1412    fn deref_mut(&mut self) -> &mut Self::Target {
1413        &mut self.app
1414    }
1415}
1416
1417impl<'a> Borrow<AppContext> for WindowContext<'a> {
1418    fn borrow(&self) -> &AppContext {
1419        &self.app
1420    }
1421}
1422
1423impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1424    fn borrow_mut(&mut self) -> &mut AppContext {
1425        &mut self.app
1426    }
1427}
1428
1429pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1430    fn app_mut(&mut self) -> &mut AppContext {
1431        self.borrow_mut()
1432    }
1433
1434    fn window(&self) -> &Window {
1435        self.borrow()
1436    }
1437
1438    fn window_mut(&mut self) -> &mut Window {
1439        self.borrow_mut()
1440    }
1441
1442    /// Pushes the given element id onto the global stack and invokes the given closure
1443    /// with a `GlobalElementId`, which disambiguates the given id in the context of its ancestor
1444    /// ids. Because elements are discarded and recreated on each frame, the `GlobalElementId` is
1445    /// used to associate state with identified elements across separate frames.
1446    fn with_element_id<R>(
1447        &mut self,
1448        id: impl Into<ElementId>,
1449        f: impl FnOnce(GlobalElementId, &mut Self) -> R,
1450    ) -> R {
1451        let keymap = self.app_mut().keymap.clone();
1452        let window = self.window_mut();
1453        window.element_id_stack.push(id.into());
1454        let global_id = window.element_id_stack.clone();
1455
1456        if window.key_matchers.get(&global_id).is_none() {
1457            window.key_matchers.insert(
1458                global_id.clone(),
1459                window
1460                    .prev_frame_key_matchers
1461                    .remove(&global_id)
1462                    .unwrap_or_else(|| KeyMatcher::new(keymap)),
1463            );
1464        }
1465
1466        let result = f(global_id, self);
1467        let window: &mut Window = self.borrow_mut();
1468        window.element_id_stack.pop();
1469        result
1470    }
1471
1472    /// Invoke the given function with the given content mask after intersecting it
1473    /// with the current mask.
1474    fn with_content_mask<R>(
1475        &mut self,
1476        mask: ContentMask<Pixels>,
1477        f: impl FnOnce(&mut Self) -> R,
1478    ) -> R {
1479        let mask = mask.intersect(&self.content_mask());
1480        self.window_mut().content_mask_stack.push(mask);
1481        let result = f(self);
1482        self.window_mut().content_mask_stack.pop();
1483        result
1484    }
1485
1486    /// Update the global element offset based on the given offset. This is used to implement
1487    /// scrolling and position drag handles.
1488    fn with_element_offset<R>(
1489        &mut self,
1490        offset: Option<Point<Pixels>>,
1491        f: impl FnOnce(&mut Self) -> R,
1492    ) -> R {
1493        let Some(offset) = offset else {
1494            return f(self);
1495        };
1496
1497        let offset = self.element_offset() + offset;
1498        self.window_mut().element_offset_stack.push(offset);
1499        let result = f(self);
1500        self.window_mut().element_offset_stack.pop();
1501        result
1502    }
1503
1504    /// Obtain the current element offset.
1505    fn element_offset(&self) -> Point<Pixels> {
1506        self.window()
1507            .element_offset_stack
1508            .last()
1509            .copied()
1510            .unwrap_or_default()
1511    }
1512
1513    /// Update or intialize state for an element with the given id that lives across multiple
1514    /// frames. If an element with this id existed in the previous frame, its state will be passed
1515    /// to the given closure. The state returned by the closure will be stored so it can be referenced
1516    /// when drawing the next frame.
1517    fn with_element_state<S, R>(
1518        &mut self,
1519        id: ElementId,
1520        f: impl FnOnce(Option<S>, &mut Self) -> (R, S),
1521    ) -> R
1522    where
1523        S: 'static,
1524    {
1525        self.with_element_id(id, |global_id, cx| {
1526            if let Some(any) = cx
1527                .window_mut()
1528                .element_states
1529                .remove(&global_id)
1530                .or_else(|| cx.window_mut().prev_frame_element_states.remove(&global_id))
1531            {
1532                // Using the extra inner option to avoid needing to reallocate a new box.
1533                let mut state_box = any
1534                    .downcast::<Option<S>>()
1535                    .expect("invalid element state type for id");
1536                let state = state_box
1537                    .take()
1538                    .expect("element state is already on the stack");
1539                let (result, state) = f(Some(state), cx);
1540                state_box.replace(state);
1541                cx.window_mut().element_states.insert(global_id, state_box);
1542                result
1543            } else {
1544                let (result, state) = f(None, cx);
1545                cx.window_mut()
1546                    .element_states
1547                    .insert(global_id, Box::new(Some(state)));
1548                result
1549            }
1550        })
1551    }
1552
1553    /// Like `with_element_state`, but for situations where the element_id is optional. If the
1554    /// id is `None`, no state will be retrieved or stored.
1555    fn with_optional_element_state<S, R>(
1556        &mut self,
1557        element_id: Option<ElementId>,
1558        f: impl FnOnce(Option<S>, &mut Self) -> (R, S),
1559    ) -> R
1560    where
1561        S: 'static,
1562    {
1563        if let Some(element_id) = element_id {
1564            self.with_element_state(element_id, f)
1565        } else {
1566            f(None, self).0
1567        }
1568    }
1569
1570    /// Obtain the current content mask.
1571    fn content_mask(&self) -> ContentMask<Pixels> {
1572        self.window()
1573            .content_mask_stack
1574            .last()
1575            .cloned()
1576            .unwrap_or_else(|| ContentMask {
1577                bounds: Bounds {
1578                    origin: Point::default(),
1579                    size: self.window().content_size,
1580                },
1581            })
1582    }
1583
1584    /// The size of an em for the base font of the application. Adjusting this value allows the
1585    /// UI to scale, just like zooming a web page.
1586    fn rem_size(&self) -> Pixels {
1587        self.window().rem_size
1588    }
1589}
1590
1591impl Borrow<Window> for WindowContext<'_> {
1592    fn borrow(&self) -> &Window {
1593        &self.window
1594    }
1595}
1596
1597impl BorrowMut<Window> for WindowContext<'_> {
1598    fn borrow_mut(&mut self) -> &mut Window {
1599        &mut self.window
1600    }
1601}
1602
1603impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
1604
1605pub struct ViewContext<'a, V> {
1606    window_cx: WindowContext<'a>,
1607    view: &'a View<V>,
1608}
1609
1610impl<V> Borrow<AppContext> for ViewContext<'_, V> {
1611    fn borrow(&self) -> &AppContext {
1612        &*self.window_cx.app
1613    }
1614}
1615
1616impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
1617    fn borrow_mut(&mut self) -> &mut AppContext {
1618        &mut *self.window_cx.app
1619    }
1620}
1621
1622impl<V> Borrow<Window> for ViewContext<'_, V> {
1623    fn borrow(&self) -> &Window {
1624        &*self.window_cx.window
1625    }
1626}
1627
1628impl<V> BorrowMut<Window> for ViewContext<'_, V> {
1629    fn borrow_mut(&mut self) -> &mut Window {
1630        &mut *self.window_cx.window
1631    }
1632}
1633
1634impl<'a, V: 'static> ViewContext<'a, V> {
1635    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
1636        Self {
1637            window_cx: WindowContext::new(app, window),
1638            view,
1639        }
1640    }
1641
1642    pub fn view(&self) -> View<V> {
1643        self.view.clone()
1644    }
1645
1646    pub fn model(&self) -> Model<V> {
1647        self.view.model.clone()
1648    }
1649
1650    pub fn stack<R>(&mut self, order: u32, f: impl FnOnce(&mut Self) -> R) -> R {
1651        self.window.z_index_stack.push(order);
1652        let result = f(self);
1653        self.window.z_index_stack.pop();
1654        result
1655    }
1656
1657    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
1658    where
1659        V: 'static,
1660    {
1661        let view = self.view();
1662        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
1663    }
1664
1665    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
1666    /// that are currently on the stack to be returned to the app.
1667    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
1668        let view = self.view().downgrade();
1669        self.window_cx.defer(move |cx| {
1670            view.update(cx, f).ok();
1671        });
1672    }
1673
1674    pub fn observe<V2, E>(
1675        &mut self,
1676        entity: &E,
1677        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
1678    ) -> Subscription
1679    where
1680        V2: 'static,
1681        V: 'static,
1682        E: Entity<V2>,
1683    {
1684        let view = self.view().downgrade();
1685        let entity_id = entity.entity_id();
1686        let entity = entity.downgrade();
1687        let window_handle = self.window.handle;
1688        self.app.observers.insert(
1689            entity_id,
1690            Box::new(move |cx| {
1691                window_handle
1692                    .update(cx, |_, cx| {
1693                        if let Some(handle) = E::upgrade_from(&entity) {
1694                            view.update(cx, |this, cx| on_notify(this, handle, cx))
1695                                .is_ok()
1696                        } else {
1697                            false
1698                        }
1699                    })
1700                    .unwrap_or(false)
1701            }),
1702        )
1703    }
1704
1705    pub fn subscribe<V2, E>(
1706        &mut self,
1707        entity: &E,
1708        mut on_event: impl FnMut(&mut V, E, &V2::Event, &mut ViewContext<'_, V>) + 'static,
1709    ) -> Subscription
1710    where
1711        V2: EventEmitter,
1712        E: Entity<V2>,
1713    {
1714        let view = self.view().downgrade();
1715        let entity_id = entity.entity_id();
1716        let handle = entity.downgrade();
1717        let window_handle = self.window.handle;
1718        self.app.event_listeners.insert(
1719            entity_id,
1720            Box::new(move |event, cx| {
1721                window_handle
1722                    .update(cx, |_, cx| {
1723                        if let Some(handle) = E::upgrade_from(&handle) {
1724                            let event = event.downcast_ref().expect("invalid event type");
1725                            view.update(cx, |this, cx| on_event(this, handle, event, cx))
1726                                .is_ok()
1727                        } else {
1728                            false
1729                        }
1730                    })
1731                    .unwrap_or(false)
1732            }),
1733        )
1734    }
1735
1736    pub fn on_release(
1737        &mut self,
1738        on_release: impl FnOnce(&mut V, &mut WindowContext) + 'static,
1739    ) -> Subscription {
1740        let window_handle = self.window.handle;
1741        self.app.release_listeners.insert(
1742            self.view.model.entity_id,
1743            Box::new(move |this, cx| {
1744                let this = this.downcast_mut().expect("invalid entity type");
1745                let _ = window_handle.update(cx, |_, cx| on_release(this, cx));
1746            }),
1747        )
1748    }
1749
1750    pub fn observe_release<V2, E>(
1751        &mut self,
1752        entity: &E,
1753        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
1754    ) -> Subscription
1755    where
1756        V: 'static,
1757        V2: 'static,
1758        E: Entity<V2>,
1759    {
1760        let view = self.view().downgrade();
1761        let entity_id = entity.entity_id();
1762        let window_handle = self.window.handle;
1763        self.app.release_listeners.insert(
1764            entity_id,
1765            Box::new(move |entity, cx| {
1766                let entity = entity.downcast_mut().expect("invalid entity type");
1767                let _ = window_handle.update(cx, |_, cx| {
1768                    view.update(cx, |this, cx| on_release(this, entity, cx))
1769                });
1770            }),
1771        )
1772    }
1773
1774    pub fn notify(&mut self) {
1775        self.window_cx.notify();
1776        self.window_cx.app.push_effect(Effect::Notify {
1777            emitter: self.view.model.entity_id,
1778        });
1779    }
1780
1781    pub fn observe_window_bounds(
1782        &mut self,
1783        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
1784    ) -> Subscription {
1785        let view = self.view.downgrade();
1786        self.window.bounds_observers.insert(
1787            (),
1788            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
1789        )
1790    }
1791
1792    pub fn observe_window_activation(
1793        &mut self,
1794        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
1795    ) -> Subscription {
1796        let view = self.view.downgrade();
1797        self.window.activation_observers.insert(
1798            (),
1799            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
1800        )
1801    }
1802
1803    pub fn on_focus_changed(
1804        &mut self,
1805        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + 'static,
1806    ) {
1807        let handle = self.view().downgrade();
1808        self.window.focus_listeners.push(Box::new(move |event, cx| {
1809            handle
1810                .update(cx, |view, cx| listener(view, event, cx))
1811                .log_err();
1812        }));
1813    }
1814
1815    pub fn with_key_listeners<R>(
1816        &mut self,
1817        key_listeners: impl IntoIterator<Item = (TypeId, KeyListener<V>)>,
1818        f: impl FnOnce(&mut Self) -> R,
1819    ) -> R {
1820        let old_stack_len = self.window.key_dispatch_stack.len();
1821        if !self.window.freeze_key_dispatch_stack {
1822            for (event_type, listener) in key_listeners {
1823                let handle = self.view().downgrade();
1824                let listener = Box::new(
1825                    move |event: &dyn Any,
1826                          context_stack: &[&DispatchContext],
1827                          phase: DispatchPhase,
1828                          cx: &mut WindowContext<'_>| {
1829                        handle
1830                            .update(cx, |view, cx| {
1831                                listener(view, event, context_stack, phase, cx)
1832                            })
1833                            .log_err()
1834                            .flatten()
1835                    },
1836                );
1837                self.window
1838                    .key_dispatch_stack
1839                    .push(KeyDispatchStackFrame::Listener {
1840                        event_type,
1841                        listener,
1842                    });
1843            }
1844        }
1845
1846        let result = f(self);
1847
1848        if !self.window.freeze_key_dispatch_stack {
1849            self.window.key_dispatch_stack.truncate(old_stack_len);
1850        }
1851
1852        result
1853    }
1854
1855    pub fn with_key_dispatch_context<R>(
1856        &mut self,
1857        context: DispatchContext,
1858        f: impl FnOnce(&mut Self) -> R,
1859    ) -> R {
1860        if context.is_empty() {
1861            return f(self);
1862        }
1863
1864        if !self.window.freeze_key_dispatch_stack {
1865            self.window
1866                .key_dispatch_stack
1867                .push(KeyDispatchStackFrame::Context(context));
1868        }
1869
1870        let result = f(self);
1871
1872        if !self.window.freeze_key_dispatch_stack {
1873            self.window.key_dispatch_stack.pop();
1874        }
1875
1876        result
1877    }
1878
1879    pub fn with_focus<R>(
1880        &mut self,
1881        focus_handle: FocusHandle,
1882        f: impl FnOnce(&mut Self) -> R,
1883    ) -> R {
1884        if let Some(parent_focus_id) = self.window.focus_stack.last().copied() {
1885            self.window
1886                .focus_parents_by_child
1887                .insert(focus_handle.id, parent_focus_id);
1888        }
1889        self.window.focus_stack.push(focus_handle.id);
1890
1891        if Some(focus_handle.id) == self.window.focus {
1892            self.window.freeze_key_dispatch_stack = true;
1893        }
1894
1895        let result = f(self);
1896
1897        self.window.focus_stack.pop();
1898        result
1899    }
1900
1901    pub fn spawn<Fut, R>(
1902        &mut self,
1903        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
1904    ) -> Task<R>
1905    where
1906        R: 'static,
1907        Fut: Future<Output = R> + 'static,
1908    {
1909        let view = self.view().downgrade();
1910        self.window_cx.spawn(|cx| f(view, cx))
1911    }
1912
1913    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
1914    where
1915        G: 'static,
1916    {
1917        let mut global = self.app.lease_global::<G>();
1918        let result = f(&mut global, self);
1919        self.app.end_global_lease(global);
1920        result
1921    }
1922
1923    pub fn observe_global<G: 'static>(
1924        &mut self,
1925        f: impl Fn(&mut V, &mut ViewContext<'_, V>) + 'static,
1926    ) -> Subscription {
1927        let window_handle = self.window.handle;
1928        let view = self.view().downgrade();
1929        self.global_observers.insert(
1930            TypeId::of::<G>(),
1931            Box::new(move |cx| {
1932                window_handle
1933                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
1934                    .unwrap_or(false)
1935            }),
1936        )
1937    }
1938
1939    pub fn on_mouse_event<Event: 'static>(
1940        &mut self,
1941        handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
1942    ) {
1943        let handle = self.view();
1944        self.window_cx.on_mouse_event(move |event, phase, cx| {
1945            handle.update(cx, |view, cx| {
1946                handler(view, event, phase, cx);
1947            })
1948        });
1949    }
1950}
1951
1952impl<V> ViewContext<'_, V>
1953where
1954    V: EventEmitter,
1955    V::Event: 'static,
1956{
1957    pub fn emit(&mut self, event: V::Event) {
1958        let emitter = self.view.model.entity_id;
1959        self.app.push_effect(Effect::Emit {
1960            emitter,
1961            event: Box::new(event),
1962        });
1963    }
1964}
1965
1966impl<V> Context for ViewContext<'_, V> {
1967    type Result<U> = U;
1968
1969    fn build_model<T: 'static>(
1970        &mut self,
1971        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
1972    ) -> Model<T> {
1973        self.window_cx.build_model(build_model)
1974    }
1975
1976    fn update_model<T: 'static, R>(
1977        &mut self,
1978        model: &Model<T>,
1979        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1980    ) -> R {
1981        self.window_cx.update_model(model, update)
1982    }
1983
1984    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1985    where
1986        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1987    {
1988        self.window_cx.update_window(window, update)
1989    }
1990}
1991
1992impl<V: 'static> VisualContext for ViewContext<'_, V> {
1993    fn build_view<W: 'static>(
1994        &mut self,
1995        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
1996    ) -> Self::Result<View<W>> {
1997        self.window_cx.build_view(build_view)
1998    }
1999
2000    fn update_view<V2: 'static, R>(
2001        &mut self,
2002        view: &View<V2>,
2003        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2004    ) -> Self::Result<R> {
2005        self.window_cx.update_view(view, update)
2006    }
2007
2008    fn replace_root_view<W>(
2009        &mut self,
2010        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2011    ) -> Self::Result<View<W>>
2012    where
2013        W: Render,
2014    {
2015        self.window_cx.replace_root_view(build_view)
2016    }
2017}
2018
2019impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2020    type Target = WindowContext<'a>;
2021
2022    fn deref(&self) -> &Self::Target {
2023        &self.window_cx
2024    }
2025}
2026
2027impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2028    fn deref_mut(&mut self) -> &mut Self::Target {
2029        &mut self.window_cx
2030    }
2031}
2032
2033// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2034slotmap::new_key_type! { pub struct WindowId; }
2035
2036impl WindowId {
2037    pub fn as_u64(&self) -> u64 {
2038        self.0.as_ffi()
2039    }
2040}
2041
2042#[derive(Deref, DerefMut)]
2043pub struct WindowHandle<V> {
2044    #[deref]
2045    #[deref_mut]
2046    pub(crate) any_handle: AnyWindowHandle,
2047    state_type: PhantomData<V>,
2048}
2049
2050impl<V: 'static + Render> WindowHandle<V> {
2051    pub fn new(id: WindowId) -> Self {
2052        WindowHandle {
2053            any_handle: AnyWindowHandle {
2054                id,
2055                state_type: TypeId::of::<V>(),
2056            },
2057            state_type: PhantomData,
2058        }
2059    }
2060
2061    pub fn update<C, R>(
2062        self,
2063        cx: &mut C,
2064        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2065    ) -> Result<R>
2066    where
2067        C: Context,
2068    {
2069        cx.update_window(self.any_handle, |root_view, cx| {
2070            let view = root_view
2071                .downcast::<V>()
2072                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2073            Ok(cx.update_view(&view, update))
2074        })?
2075    }
2076}
2077
2078impl<V> Copy for WindowHandle<V> {}
2079
2080impl<V> Clone for WindowHandle<V> {
2081    fn clone(&self) -> Self {
2082        WindowHandle {
2083            any_handle: self.any_handle,
2084            state_type: PhantomData,
2085        }
2086    }
2087}
2088
2089impl<V> PartialEq for WindowHandle<V> {
2090    fn eq(&self, other: &Self) -> bool {
2091        self.any_handle == other.any_handle
2092    }
2093}
2094
2095impl<V> Eq for WindowHandle<V> {}
2096
2097impl<V> Hash for WindowHandle<V> {
2098    fn hash<H: Hasher>(&self, state: &mut H) {
2099        self.any_handle.hash(state);
2100    }
2101}
2102
2103impl<V: 'static> Into<AnyWindowHandle> for WindowHandle<V> {
2104    fn into(self) -> AnyWindowHandle {
2105        self.any_handle
2106    }
2107}
2108
2109#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2110pub struct AnyWindowHandle {
2111    pub(crate) id: WindowId,
2112    state_type: TypeId,
2113}
2114
2115impl AnyWindowHandle {
2116    pub fn window_id(&self) -> WindowId {
2117        self.id
2118    }
2119
2120    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2121        if TypeId::of::<T>() == self.state_type {
2122            Some(WindowHandle {
2123                any_handle: *self,
2124                state_type: PhantomData,
2125            })
2126        } else {
2127            None
2128        }
2129    }
2130
2131    pub fn update<C, R>(
2132        self,
2133        cx: &mut C,
2134        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2135    ) -> Result<R>
2136    where
2137        C: Context,
2138    {
2139        cx.update_window(self, update)
2140    }
2141}
2142
2143#[cfg(any(test, feature = "test-support"))]
2144impl From<SmallVec<[u32; 16]>> for StackingOrder {
2145    fn from(small_vec: SmallVec<[u32; 16]>) -> Self {
2146        StackingOrder(small_vec)
2147    }
2148}
2149
2150#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2151pub enum ElementId {
2152    View(EntityId),
2153    Number(usize),
2154    Name(SharedString),
2155    FocusHandle(FocusId),
2156}
2157
2158impl From<EntityId> for ElementId {
2159    fn from(id: EntityId) -> Self {
2160        ElementId::View(id)
2161    }
2162}
2163
2164impl From<usize> for ElementId {
2165    fn from(id: usize) -> Self {
2166        ElementId::Number(id)
2167    }
2168}
2169
2170impl From<i32> for ElementId {
2171    fn from(id: i32) -> Self {
2172        Self::Number(id as usize)
2173    }
2174}
2175
2176impl From<SharedString> for ElementId {
2177    fn from(name: SharedString) -> Self {
2178        ElementId::Name(name)
2179    }
2180}
2181
2182impl From<&'static str> for ElementId {
2183    fn from(name: &'static str) -> Self {
2184        ElementId::Name(name.into())
2185    }
2186}
2187
2188impl<'a> From<&'a FocusHandle> for ElementId {
2189    fn from(handle: &'a FocusHandle) -> Self {
2190        ElementId::FocusHandle(handle.id)
2191    }
2192}