window.rs

   1#![deny(missing_docs)]
   2
   3use crate::{
   4    px, size, transparent_black, Action, AnyDrag, AnyTooltip, AnyView, AppContext, Arena,
   5    AsyncWindowContext, AvailableSpace, Bounds, BoxShadow, Context, Corners, CursorStyle,
   6    DevicePixels, DispatchActionListener, DispatchNodeId, DispatchTree, DisplayId, Edges, Effect,
   7    Entity, EntityId, EventEmitter, FileDropEvent, Flatten, FontId, GlobalElementId, GlyphId, Hsla,
   8    ImageData, IsZero, KeyBinding, KeyContext, KeyDownEvent, KeyEvent, KeystrokeEvent, LayoutId,
   9    Model, ModelContext, Modifiers, MonochromeSprite, MouseButton, MouseEvent, MouseMoveEvent,
  10    MouseUpEvent, Path, Pixels, PlatformAtlas, PlatformDisplay, PlatformInput,
  11    PlatformInputHandler, PlatformWindow, Point, PolychromeSprite, PromptLevel, Quad, Render,
  12    RenderGlyphParams, RenderImageParams, RenderSvgParams, ScaledPixels, Scene, Shadow,
  13    SharedString, Size, Style, SubscriberSet, Subscription, Surface, TaffyLayoutEngine, Task,
  14    Underline, UnderlineStyle, View, VisualContext, WeakView, WindowBounds, WindowOptions,
  15    SUBPIXEL_VARIANTS,
  16};
  17use anyhow::{anyhow, Context as _, Result};
  18use collections::{FxHashMap, FxHashSet};
  19use derive_more::{Deref, DerefMut};
  20use futures::{
  21    channel::{mpsc, oneshot},
  22    StreamExt,
  23};
  24use media::core_video::CVImageBuffer;
  25use parking_lot::RwLock;
  26use slotmap::SlotMap;
  27use smallvec::SmallVec;
  28use std::{
  29    any::{Any, TypeId},
  30    borrow::{Borrow, BorrowMut, Cow},
  31    cell::RefCell,
  32    collections::hash_map::Entry,
  33    fmt::Debug,
  34    future::Future,
  35    hash::{Hash, Hasher},
  36    marker::PhantomData,
  37    mem,
  38    rc::Rc,
  39    sync::{
  40        atomic::{AtomicUsize, Ordering::SeqCst},
  41        Arc,
  42    },
  43};
  44use util::{post_inc, ResultExt};
  45
  46const ACTIVE_DRAG_Z_INDEX: u8 = 1;
  47
  48/// A global stacking order, which is created by stacking successive z-index values.
  49/// Each z-index will always be interpreted in the context of its parent z-index.
  50#[derive(Deref, DerefMut, Clone, Ord, PartialOrd, PartialEq, Eq, Default)]
  51pub struct StackingOrder {
  52    #[deref]
  53    #[deref_mut]
  54    context_stack: SmallVec<[u8; 64]>,
  55    id: u32,
  56}
  57
  58impl std::fmt::Debug for StackingOrder {
  59    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  60        let mut stacks = self.context_stack.iter().peekable();
  61        write!(f, "[({}): ", self.id)?;
  62        while let Some(z_index) = stacks.next() {
  63            write!(f, "{z_index}")?;
  64            if stacks.peek().is_some() {
  65                write!(f, "->")?;
  66            }
  67        }
  68        write!(f, "]")?;
  69        Ok(())
  70    }
  71}
  72
  73/// Represents the two different phases when dispatching events.
  74#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  75pub enum DispatchPhase {
  76    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  77    /// invoked front to back and keyboard event listeners are invoked from the focused element
  78    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  79    /// registering event listeners.
  80    #[default]
  81    Bubble,
  82    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  83    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  84    /// is used for special purposes such as clearing the "pressed" state for click events. If
  85    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  86    /// outside of the immediate region may rely on detecting non-local events during this phase.
  87    Capture,
  88}
  89
  90impl DispatchPhase {
  91    /// Returns true if this represents the "bubble" phase.
  92    pub fn bubble(self) -> bool {
  93        self == DispatchPhase::Bubble
  94    }
  95
  96    /// Returns true if this represents the "capture" phase.
  97    pub fn capture(self) -> bool {
  98        self == DispatchPhase::Capture
  99    }
 100}
 101
 102type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
 103type AnyMouseListener = Box<dyn FnMut(&dyn Any, DispatchPhase, &mut WindowContext) + 'static>;
 104type AnyWindowFocusListener = Box<dyn FnMut(&FocusEvent, &mut WindowContext) -> bool + 'static>;
 105
 106struct FocusEvent {
 107    previous_focus_path: SmallVec<[FocusId; 8]>,
 108    current_focus_path: SmallVec<[FocusId; 8]>,
 109}
 110
 111slotmap::new_key_type! {
 112    /// A globally unique identifier for a focusable element.
 113    pub struct FocusId;
 114}
 115
 116thread_local! {
 117    pub(crate) static ELEMENT_ARENA: RefCell<Arena> = RefCell::new(Arena::new(4 * 1024 * 1024));
 118}
 119
 120impl FocusId {
 121    /// Obtains whether the element associated with this handle is currently focused.
 122    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 123        cx.window.focus == Some(*self)
 124    }
 125
 126    /// Obtains whether the element associated with this handle contains the focused
 127    /// element or is itself focused.
 128    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 129        cx.focused()
 130            .map_or(false, |focused| self.contains(focused.id, cx))
 131    }
 132
 133    /// Obtains whether the element associated with this handle is contained within the
 134    /// focused element or is itself focused.
 135    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 136        let focused = cx.focused();
 137        focused.map_or(false, |focused| focused.id.contains(*self, cx))
 138    }
 139
 140    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 141    pub(crate) fn contains(&self, other: Self, cx: &WindowContext) -> bool {
 142        cx.window
 143            .rendered_frame
 144            .dispatch_tree
 145            .focus_contains(*self, other)
 146    }
 147}
 148
 149/// A handle which can be used to track and manipulate the focused element in a window.
 150pub struct FocusHandle {
 151    pub(crate) id: FocusId,
 152    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 153}
 154
 155impl std::fmt::Debug for FocusHandle {
 156    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 157        f.write_fmt(format_args!("FocusHandle({:?})", self.id))
 158    }
 159}
 160
 161impl FocusHandle {
 162    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
 163        let id = handles.write().insert(AtomicUsize::new(1));
 164        Self {
 165            id,
 166            handles: handles.clone(),
 167        }
 168    }
 169
 170    pub(crate) fn for_id(
 171        id: FocusId,
 172        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 173    ) -> Option<Self> {
 174        let lock = handles.read();
 175        let ref_count = lock.get(id)?;
 176        if ref_count.load(SeqCst) == 0 {
 177            None
 178        } else {
 179            ref_count.fetch_add(1, SeqCst);
 180            Some(Self {
 181                id,
 182                handles: handles.clone(),
 183            })
 184        }
 185    }
 186
 187    /// Moves the focus to the element associated with this handle.
 188    pub fn focus(&self, cx: &mut WindowContext) {
 189        cx.focus(self)
 190    }
 191
 192    /// Obtains whether the element associated with this handle is currently focused.
 193    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 194        self.id.is_focused(cx)
 195    }
 196
 197    /// Obtains whether the element associated with this handle contains the focused
 198    /// element or is itself focused.
 199    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 200        self.id.contains_focused(cx)
 201    }
 202
 203    /// Obtains whether the element associated with this handle is contained within the
 204    /// focused element or is itself focused.
 205    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 206        self.id.within_focused(cx)
 207    }
 208
 209    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 210    pub fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 211        self.id.contains(other.id, cx)
 212    }
 213}
 214
 215impl Clone for FocusHandle {
 216    fn clone(&self) -> Self {
 217        Self::for_id(self.id, &self.handles).unwrap()
 218    }
 219}
 220
 221impl PartialEq for FocusHandle {
 222    fn eq(&self, other: &Self) -> bool {
 223        self.id == other.id
 224    }
 225}
 226
 227impl Eq for FocusHandle {}
 228
 229impl Drop for FocusHandle {
 230    fn drop(&mut self) {
 231        self.handles
 232            .read()
 233            .get(self.id)
 234            .unwrap()
 235            .fetch_sub(1, SeqCst);
 236    }
 237}
 238
 239/// FocusableView allows users of your view to easily
 240/// focus it (using cx.focus_view(view))
 241pub trait FocusableView: 'static + Render {
 242    /// Returns the focus handle associated with this view.
 243    fn focus_handle(&self, cx: &AppContext) -> FocusHandle;
 244}
 245
 246/// ManagedView is a view (like a Modal, Popover, Menu, etc.)
 247/// where the lifecycle of the view is handled by another view.
 248pub trait ManagedView: FocusableView + EventEmitter<DismissEvent> {}
 249
 250impl<M: FocusableView + EventEmitter<DismissEvent>> ManagedView for M {}
 251
 252/// Emitted by implementers of [`ManagedView`] to indicate the view should be dismissed, such as when a view is presented as a modal.
 253pub struct DismissEvent;
 254
 255// Holds the state for a specific window.
 256#[doc(hidden)]
 257pub struct Window {
 258    pub(crate) handle: AnyWindowHandle,
 259    pub(crate) removed: bool,
 260    pub(crate) platform_window: Box<dyn PlatformWindow>,
 261    display_id: DisplayId,
 262    sprite_atlas: Arc<dyn PlatformAtlas>,
 263    rem_size: Pixels,
 264    viewport_size: Size<Pixels>,
 265    layout_engine: Option<TaffyLayoutEngine>,
 266    pub(crate) root_view: Option<AnyView>,
 267    pub(crate) element_id_stack: GlobalElementId,
 268    pub(crate) rendered_frame: Frame,
 269    pub(crate) next_frame: Frame,
 270    pub(crate) dirty_views: FxHashSet<EntityId>,
 271    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 272    focus_listeners: SubscriberSet<(), AnyWindowFocusListener>,
 273    focus_lost_listeners: SubscriberSet<(), AnyObserver>,
 274    default_prevented: bool,
 275    mouse_position: Point<Pixels>,
 276    modifiers: Modifiers,
 277    scale_factor: f32,
 278    bounds: WindowBounds,
 279    bounds_observers: SubscriberSet<(), AnyObserver>,
 280    active: bool,
 281    pub(crate) dirty: bool,
 282    pub(crate) refreshing: bool,
 283    pub(crate) drawing: bool,
 284    activation_observers: SubscriberSet<(), AnyObserver>,
 285    pub(crate) focus: Option<FocusId>,
 286    focus_enabled: bool,
 287
 288    #[cfg(any(test, feature = "test-support"))]
 289    pub(crate) focus_invalidated: bool,
 290}
 291
 292pub(crate) struct ElementStateBox {
 293    inner: Box<dyn Any>,
 294    parent_view_id: EntityId,
 295    #[cfg(debug_assertions)]
 296    type_name: &'static str,
 297}
 298
 299struct RequestedInputHandler {
 300    view_id: EntityId,
 301    handler: Option<Box<dyn PlatformInputHandler>>,
 302}
 303
 304struct TooltipRequest {
 305    view_id: EntityId,
 306    tooltip: AnyTooltip,
 307}
 308
 309pub(crate) struct Frame {
 310    focus: Option<FocusId>,
 311    window_active: bool,
 312    pub(crate) element_states: FxHashMap<GlobalElementId, ElementStateBox>,
 313    mouse_listeners: FxHashMap<TypeId, Vec<(StackingOrder, EntityId, AnyMouseListener)>>,
 314    pub(crate) dispatch_tree: DispatchTree,
 315    pub(crate) scene: Scene,
 316    pub(crate) depth_map: Vec<(StackingOrder, EntityId, Bounds<Pixels>)>,
 317    pub(crate) z_index_stack: StackingOrder,
 318    pub(crate) next_stacking_order_id: u32,
 319    next_root_z_index: u8,
 320    content_mask_stack: Vec<ContentMask<Pixels>>,
 321    element_offset_stack: Vec<Point<Pixels>>,
 322    requested_input_handler: Option<RequestedInputHandler>,
 323    tooltip_request: Option<TooltipRequest>,
 324    cursor_styles: FxHashMap<EntityId, CursorStyle>,
 325    requested_cursor_style: Option<CursorStyle>,
 326    pub(crate) view_stack: Vec<EntityId>,
 327    pub(crate) reused_views: FxHashSet<EntityId>,
 328}
 329
 330impl Frame {
 331    fn new(dispatch_tree: DispatchTree) -> Self {
 332        Frame {
 333            focus: None,
 334            window_active: false,
 335            element_states: FxHashMap::default(),
 336            mouse_listeners: FxHashMap::default(),
 337            dispatch_tree,
 338            scene: Scene::default(),
 339            depth_map: Vec::new(),
 340            z_index_stack: StackingOrder::default(),
 341            next_stacking_order_id: 0,
 342            next_root_z_index: 0,
 343            content_mask_stack: Vec::new(),
 344            element_offset_stack: Vec::new(),
 345            requested_input_handler: None,
 346            tooltip_request: None,
 347            cursor_styles: FxHashMap::default(),
 348            requested_cursor_style: None,
 349            view_stack: Vec::new(),
 350            reused_views: FxHashSet::default(),
 351        }
 352    }
 353
 354    fn clear(&mut self) {
 355        self.element_states.clear();
 356        self.mouse_listeners.values_mut().for_each(Vec::clear);
 357        self.dispatch_tree.clear();
 358        self.depth_map.clear();
 359        self.next_stacking_order_id = 0;
 360        self.next_root_z_index = 0;
 361        self.reused_views.clear();
 362        self.scene.clear();
 363        self.requested_input_handler.take();
 364        self.tooltip_request.take();
 365        self.cursor_styles.clear();
 366        self.requested_cursor_style.take();
 367        debug_assert_eq!(self.view_stack.len(), 0);
 368    }
 369
 370    fn focus_path(&self) -> SmallVec<[FocusId; 8]> {
 371        self.focus
 372            .map(|focus_id| self.dispatch_tree.focus_path(focus_id))
 373            .unwrap_or_default()
 374    }
 375
 376    fn finish(&mut self, prev_frame: &mut Self) {
 377        // Reuse mouse listeners that didn't change since the last frame.
 378        for (type_id, listeners) in &mut prev_frame.mouse_listeners {
 379            let next_listeners = self.mouse_listeners.entry(*type_id).or_default();
 380            for (order, view_id, listener) in listeners.drain(..) {
 381                if self.reused_views.contains(&view_id) {
 382                    next_listeners.push((order, view_id, listener));
 383                }
 384            }
 385        }
 386
 387        // Reuse entries in the depth map that didn't change since the last frame.
 388        for (order, view_id, bounds) in prev_frame.depth_map.drain(..) {
 389            if self.reused_views.contains(&view_id) {
 390                match self
 391                    .depth_map
 392                    .binary_search_by(|(level, _, _)| order.cmp(level))
 393                {
 394                    Ok(i) | Err(i) => self.depth_map.insert(i, (order, view_id, bounds)),
 395                }
 396            }
 397        }
 398
 399        // Retain element states for views that didn't change since the last frame.
 400        for (element_id, state) in prev_frame.element_states.drain() {
 401            if self.reused_views.contains(&state.parent_view_id) {
 402                self.element_states.entry(element_id).or_insert(state);
 403            }
 404        }
 405
 406        // Reuse geometry that didn't change since the last frame.
 407        self.scene
 408            .reuse_views(&self.reused_views, &mut prev_frame.scene);
 409        self.scene.finish();
 410    }
 411}
 412
 413impl Window {
 414    pub(crate) fn new(
 415        handle: AnyWindowHandle,
 416        options: WindowOptions,
 417        cx: &mut AppContext,
 418    ) -> Self {
 419        let platform_window = cx.platform.open_window(handle, options);
 420        let display_id = platform_window.display().id();
 421        let sprite_atlas = platform_window.sprite_atlas();
 422        let mouse_position = platform_window.mouse_position();
 423        let modifiers = platform_window.modifiers();
 424        let content_size = platform_window.content_size();
 425        let scale_factor = platform_window.scale_factor();
 426        let bounds = platform_window.bounds();
 427
 428        platform_window.on_request_frame(Box::new({
 429            let mut cx = cx.to_async();
 430            move || {
 431                handle.update(&mut cx, |_, cx| cx.draw()).log_err();
 432            }
 433        }));
 434        platform_window.on_resize(Box::new({
 435            let mut cx = cx.to_async();
 436            move |_, _| {
 437                handle
 438                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 439                    .log_err();
 440            }
 441        }));
 442        platform_window.on_moved(Box::new({
 443            let mut cx = cx.to_async();
 444            move || {
 445                handle
 446                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 447                    .log_err();
 448            }
 449        }));
 450        platform_window.on_active_status_change(Box::new({
 451            let mut cx = cx.to_async();
 452            move |active| {
 453                handle
 454                    .update(&mut cx, |_, cx| {
 455                        cx.window.active = active;
 456                        cx.window
 457                            .activation_observers
 458                            .clone()
 459                            .retain(&(), |callback| callback(cx));
 460                    })
 461                    .log_err();
 462            }
 463        }));
 464
 465        platform_window.on_input({
 466            let mut cx = cx.to_async();
 467            Box::new(move |event| {
 468                handle
 469                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 470                    .log_err()
 471                    .unwrap_or(false)
 472            })
 473        });
 474
 475        Window {
 476            handle,
 477            removed: false,
 478            platform_window,
 479            display_id,
 480            sprite_atlas,
 481            rem_size: px(16.),
 482            viewport_size: content_size,
 483            layout_engine: Some(TaffyLayoutEngine::new()),
 484            root_view: None,
 485            element_id_stack: GlobalElementId::default(),
 486            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 487            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 488            dirty_views: FxHashSet::default(),
 489            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 490            focus_listeners: SubscriberSet::new(),
 491            focus_lost_listeners: SubscriberSet::new(),
 492            default_prevented: true,
 493            mouse_position,
 494            modifiers,
 495            scale_factor,
 496            bounds,
 497            bounds_observers: SubscriberSet::new(),
 498            active: false,
 499            dirty: false,
 500            refreshing: false,
 501            drawing: false,
 502            activation_observers: SubscriberSet::new(),
 503            focus: None,
 504            focus_enabled: true,
 505
 506            #[cfg(any(test, feature = "test-support"))]
 507            focus_invalidated: false,
 508        }
 509    }
 510}
 511
 512/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 513/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 514/// to leave room to support more complex shapes in the future.
 515#[derive(Clone, Debug, Default, PartialEq, Eq)]
 516#[repr(C)]
 517pub struct ContentMask<P: Clone + Default + Debug> {
 518    /// The bounds
 519    pub bounds: Bounds<P>,
 520}
 521
 522impl ContentMask<Pixels> {
 523    /// Scale the content mask's pixel units by the given scaling factor.
 524    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 525        ContentMask {
 526            bounds: self.bounds.scale(factor),
 527        }
 528    }
 529
 530    /// Intersect the content mask with the given content mask.
 531    pub fn intersect(&self, other: &Self) -> Self {
 532        let bounds = self.bounds.intersect(&other.bounds);
 533        ContentMask { bounds }
 534    }
 535}
 536
 537/// Provides access to application state in the context of a single window. Derefs
 538/// to an [`AppContext`], so you can also pass a [`WindowContext`] to any method that takes
 539/// an [`AppContext`] and call any [`AppContext`] methods.
 540pub struct WindowContext<'a> {
 541    pub(crate) app: &'a mut AppContext,
 542    pub(crate) window: &'a mut Window,
 543}
 544
 545impl<'a> WindowContext<'a> {
 546    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 547        Self { app, window }
 548    }
 549
 550    /// Obtain a handle to the window that belongs to this context.
 551    pub fn window_handle(&self) -> AnyWindowHandle {
 552        self.window.handle
 553    }
 554
 555    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 556    pub fn refresh(&mut self) {
 557        if !self.window.drawing {
 558            self.window.refreshing = true;
 559            self.window.dirty = true;
 560        }
 561    }
 562
 563    /// Close this window.
 564    pub fn remove_window(&mut self) {
 565        self.window.removed = true;
 566    }
 567
 568    /// Obtain a new [`FocusHandle`], which allows you to track and manipulate the keyboard focus
 569    /// for elements rendered within this window.
 570    pub fn focus_handle(&mut self) -> FocusHandle {
 571        FocusHandle::new(&self.window.focus_handles)
 572    }
 573
 574    /// Obtain the currently focused [`FocusHandle`]. If no elements are focused, returns `None`.
 575    pub fn focused(&self) -> Option<FocusHandle> {
 576        self.window
 577            .focus
 578            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 579    }
 580
 581    /// Move focus to the element associated with the given [`FocusHandle`].
 582    pub fn focus(&mut self, handle: &FocusHandle) {
 583        if !self.window.focus_enabled || self.window.focus == Some(handle.id) {
 584            return;
 585        }
 586
 587        self.window.focus = Some(handle.id);
 588        self.window
 589            .rendered_frame
 590            .dispatch_tree
 591            .clear_pending_keystrokes();
 592
 593        #[cfg(any(test, feature = "test-support"))]
 594        {
 595            self.window.focus_invalidated = true;
 596        }
 597
 598        self.refresh();
 599    }
 600
 601    /// Remove focus from all elements within this context's window.
 602    pub fn blur(&mut self) {
 603        if !self.window.focus_enabled {
 604            return;
 605        }
 606
 607        self.window.focus = None;
 608        self.refresh();
 609    }
 610
 611    /// Blur the window and don't allow anything in it to be focused again.
 612    pub fn disable_focus(&mut self) {
 613        self.blur();
 614        self.window.focus_enabled = false;
 615    }
 616
 617    /// Dispatch the given action on the currently focused element.
 618    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 619        let focus_handle = self.focused();
 620
 621        self.defer(move |cx| {
 622            let node_id = focus_handle
 623                .and_then(|handle| {
 624                    cx.window
 625                        .rendered_frame
 626                        .dispatch_tree
 627                        .focusable_node_id(handle.id)
 628                })
 629                .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 630
 631            cx.propagate_event = true;
 632            cx.dispatch_action_on_node(node_id, action);
 633        })
 634    }
 635
 636    pub(crate) fn dispatch_keystroke_observers(
 637        &mut self,
 638        event: &dyn Any,
 639        action: Option<Box<dyn Action>>,
 640    ) {
 641        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 642            return;
 643        };
 644
 645        self.keystroke_observers
 646            .clone()
 647            .retain(&(), move |callback| {
 648                (callback)(
 649                    &KeystrokeEvent {
 650                        keystroke: key_down_event.keystroke.clone(),
 651                        action: action.as_ref().map(|action| action.boxed_clone()),
 652                    },
 653                    self,
 654                );
 655                true
 656            });
 657    }
 658
 659    pub(crate) fn clear_pending_keystrokes(&mut self) {
 660        self.window
 661            .rendered_frame
 662            .dispatch_tree
 663            .clear_pending_keystrokes();
 664        self.window
 665            .next_frame
 666            .dispatch_tree
 667            .clear_pending_keystrokes();
 668    }
 669
 670    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 671    /// that are currently on the stack to be returned to the app.
 672    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 673        let handle = self.window.handle;
 674        self.app.defer(move |cx| {
 675            handle.update(cx, |_, cx| f(cx)).ok();
 676        });
 677    }
 678
 679    /// Subscribe to events emitted by a model or view.
 680    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
 681    /// The callback will be invoked a handle to the emitting entity (either a [`View`] or [`Model`]), the event, and a window context for the current window.
 682    pub fn subscribe<Emitter, E, Evt>(
 683        &mut self,
 684        entity: &E,
 685        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 686    ) -> Subscription
 687    where
 688        Emitter: EventEmitter<Evt>,
 689        E: Entity<Emitter>,
 690        Evt: 'static,
 691    {
 692        let entity_id = entity.entity_id();
 693        let entity = entity.downgrade();
 694        let window_handle = self.window.handle;
 695        let (subscription, activate) = self.app.event_listeners.insert(
 696            entity_id,
 697            (
 698                TypeId::of::<Evt>(),
 699                Box::new(move |event, cx| {
 700                    window_handle
 701                        .update(cx, |_, cx| {
 702                            if let Some(handle) = E::upgrade_from(&entity) {
 703                                let event = event.downcast_ref().expect("invalid event type");
 704                                on_event(handle, event, cx);
 705                                true
 706                            } else {
 707                                false
 708                            }
 709                        })
 710                        .unwrap_or(false)
 711                }),
 712            ),
 713        );
 714        self.app.defer(move |_| activate());
 715        subscription
 716    }
 717
 718    /// Create an `AsyncWindowContext`, which has a static lifetime and can be held across
 719    /// await points in async code.
 720    pub fn to_async(&self) -> AsyncWindowContext {
 721        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 722    }
 723
 724    /// Schedule the given closure to be run directly after the current frame is rendered.
 725    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 726        let handle = self.window.handle;
 727        let display_id = self.window.display_id;
 728
 729        let mut frame_consumers = std::mem::take(&mut self.app.frame_consumers);
 730        if let Entry::Vacant(e) = frame_consumers.entry(display_id) {
 731            let (tx, mut rx) = mpsc::unbounded::<()>();
 732            self.platform.set_display_link_output_callback(
 733                display_id,
 734                Box::new(move |_current_time, _output_time| _ = tx.unbounded_send(())),
 735            );
 736
 737            let consumer_task = self.app.spawn(|cx| async move {
 738                while rx.next().await.is_some() {
 739                    cx.update(|cx| {
 740                        for callback in cx
 741                            .next_frame_callbacks
 742                            .get_mut(&display_id)
 743                            .unwrap()
 744                            .drain(..)
 745                            .collect::<SmallVec<[_; 32]>>()
 746                        {
 747                            callback(cx);
 748                        }
 749                    })
 750                    .ok();
 751
 752                    // Flush effects, then stop the display link if no new next_frame_callbacks have been added.
 753
 754                    cx.update(|cx| {
 755                        if cx.next_frame_callbacks.is_empty() {
 756                            cx.platform.stop_display_link(display_id);
 757                        }
 758                    })
 759                    .ok();
 760                }
 761            });
 762            e.insert(consumer_task);
 763        }
 764        debug_assert!(self.app.frame_consumers.is_empty());
 765        self.app.frame_consumers = frame_consumers;
 766
 767        if self.next_frame_callbacks.is_empty() {
 768            self.platform.start_display_link(display_id);
 769        }
 770
 771        self.next_frame_callbacks
 772            .entry(display_id)
 773            .or_default()
 774            .push(Box::new(move |cx: &mut AppContext| {
 775                cx.update_window(handle, |_root_view, cx| callback(cx)).ok();
 776            }));
 777    }
 778
 779    /// Spawn the future returned by the given closure on the application thread pool.
 780    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 781    /// use within your future.
 782    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 783    where
 784        R: 'static,
 785        Fut: Future<Output = R> + 'static,
 786    {
 787        self.app
 788            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 789    }
 790
 791    /// Update the global of the given type. The given closure is given simultaneous mutable
 792    /// access both to the global and the context.
 793    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 794    where
 795        G: 'static,
 796    {
 797        let mut global = self.app.lease_global::<G>();
 798        let result = f(&mut global, self);
 799        self.app.end_global_lease(global);
 800        result
 801    }
 802
 803    #[must_use]
 804    /// Add a node to the layout tree for the current frame. Takes the `Style` of the element for which
 805    /// layout is being requested, along with the layout ids of any children. This method is called during
 806    /// calls to the `Element::layout` trait method and enables any element to participate in layout.
 807    pub fn request_layout(
 808        &mut self,
 809        style: &Style,
 810        children: impl IntoIterator<Item = LayoutId>,
 811    ) -> LayoutId {
 812        self.app.layout_id_buffer.clear();
 813        self.app.layout_id_buffer.extend(children);
 814        let rem_size = self.rem_size();
 815
 816        self.window.layout_engine.as_mut().unwrap().request_layout(
 817            style,
 818            rem_size,
 819            &self.app.layout_id_buffer,
 820        )
 821    }
 822
 823    /// Add a node to the layout tree for the current frame. Instead of taking a `Style` and children,
 824    /// this variant takes a function that is invoked during layout so you can use arbitrary logic to
 825    /// determine the element's size. One place this is used internally is when measuring text.
 826    ///
 827    /// The given closure is invoked at layout time with the known dimensions and available space and
 828    /// returns a `Size`.
 829    pub fn request_measured_layout<
 830        F: FnMut(Size<Option<Pixels>>, Size<AvailableSpace>, &mut WindowContext) -> Size<Pixels>
 831            + 'static,
 832    >(
 833        &mut self,
 834        style: Style,
 835        measure: F,
 836    ) -> LayoutId {
 837        let rem_size = self.rem_size();
 838        self.window
 839            .layout_engine
 840            .as_mut()
 841            .unwrap()
 842            .request_measured_layout(style, rem_size, measure)
 843    }
 844
 845    pub(crate) fn layout_style(&self, layout_id: LayoutId) -> Option<&Style> {
 846        self.window
 847            .layout_engine
 848            .as_ref()
 849            .unwrap()
 850            .requested_style(layout_id)
 851    }
 852
 853    /// Compute the layout for the given id within the given available space.
 854    /// This method is called for its side effect, typically by the framework prior to painting.
 855    /// After calling it, you can request the bounds of the given layout node id or any descendant.
 856    pub fn compute_layout(&mut self, layout_id: LayoutId, available_space: Size<AvailableSpace>) {
 857        let mut layout_engine = self.window.layout_engine.take().unwrap();
 858        layout_engine.compute_layout(layout_id, available_space, self);
 859        self.window.layout_engine = Some(layout_engine);
 860    }
 861
 862    /// Obtain the bounds computed for the given LayoutId relative to the window. This method should not
 863    /// be invoked until the paint phase begins, and will usually be invoked by GPUI itself automatically
 864    /// in order to pass your element its `Bounds` automatically.
 865    pub fn layout_bounds(&mut self, layout_id: LayoutId) -> Bounds<Pixels> {
 866        let mut bounds = self
 867            .window
 868            .layout_engine
 869            .as_mut()
 870            .unwrap()
 871            .layout_bounds(layout_id)
 872            .map(Into::into);
 873        bounds.origin += self.element_offset();
 874        bounds
 875    }
 876
 877    fn window_bounds_changed(&mut self) {
 878        self.window.scale_factor = self.window.platform_window.scale_factor();
 879        self.window.viewport_size = self.window.platform_window.content_size();
 880        self.window.bounds = self.window.platform_window.bounds();
 881        self.window.display_id = self.window.platform_window.display().id();
 882        self.refresh();
 883
 884        self.window
 885            .bounds_observers
 886            .clone()
 887            .retain(&(), |callback| callback(self));
 888    }
 889
 890    /// Returns the bounds of the current window in the global coordinate space, which could span across multiple displays.
 891    pub fn window_bounds(&self) -> WindowBounds {
 892        self.window.bounds
 893    }
 894
 895    /// Returns the size of the drawable area within the window.
 896    pub fn viewport_size(&self) -> Size<Pixels> {
 897        self.window.viewport_size
 898    }
 899
 900    /// Returns whether this window is focused by the operating system (receiving key events).
 901    pub fn is_window_active(&self) -> bool {
 902        self.window.active
 903    }
 904
 905    /// Toggle zoom on the window.
 906    pub fn zoom_window(&self) {
 907        self.window.platform_window.zoom();
 908    }
 909
 910    /// Update the window's title at the platform level.
 911    pub fn set_window_title(&mut self, title: &str) {
 912        self.window.platform_window.set_title(title);
 913    }
 914
 915    /// Mark the window as dirty at the platform level.
 916    pub fn set_window_edited(&mut self, edited: bool) {
 917        self.window.platform_window.set_edited(edited);
 918    }
 919
 920    /// Determine the display on which the window is visible.
 921    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 922        self.platform
 923            .displays()
 924            .into_iter()
 925            .find(|display| display.id() == self.window.display_id)
 926    }
 927
 928    /// Show the platform character palette.
 929    pub fn show_character_palette(&self) {
 930        self.window.platform_window.show_character_palette();
 931    }
 932
 933    /// The scale factor of the display associated with the window. For example, it could
 934    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 935    /// be rendered as two pixels on screen.
 936    pub fn scale_factor(&self) -> f32 {
 937        self.window.scale_factor
 938    }
 939
 940    /// The size of an em for the base font of the application. Adjusting this value allows the
 941    /// UI to scale, just like zooming a web page.
 942    pub fn rem_size(&self) -> Pixels {
 943        self.window.rem_size
 944    }
 945
 946    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 947    /// UI to scale, just like zooming a web page.
 948    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 949        self.window.rem_size = rem_size.into();
 950    }
 951
 952    /// The line height associated with the current text style.
 953    pub fn line_height(&self) -> Pixels {
 954        let rem_size = self.rem_size();
 955        let text_style = self.text_style();
 956        text_style
 957            .line_height
 958            .to_pixels(text_style.font_size, rem_size)
 959    }
 960
 961    /// Call to prevent the default action of an event. Currently only used to prevent
 962    /// parent elements from becoming focused on mouse down.
 963    pub fn prevent_default(&mut self) {
 964        self.window.default_prevented = true;
 965    }
 966
 967    /// Obtain whether default has been prevented for the event currently being dispatched.
 968    pub fn default_prevented(&self) -> bool {
 969        self.window.default_prevented
 970    }
 971
 972    /// Register a mouse event listener on the window for the next frame. The type of event
 973    /// is determined by the first parameter of the given listener. When the next frame is rendered
 974    /// the listener will be cleared.
 975    pub fn on_mouse_event<Event: MouseEvent>(
 976        &mut self,
 977        mut handler: impl FnMut(&Event, DispatchPhase, &mut WindowContext) + 'static,
 978    ) {
 979        let view_id = self.parent_view_id();
 980        let order = self.window.next_frame.z_index_stack.clone();
 981        self.window
 982            .next_frame
 983            .mouse_listeners
 984            .entry(TypeId::of::<Event>())
 985            .or_default()
 986            .push((
 987                order,
 988                view_id,
 989                Box::new(
 990                    move |event: &dyn Any, phase: DispatchPhase, cx: &mut WindowContext<'_>| {
 991                        handler(event.downcast_ref().unwrap(), phase, cx)
 992                    },
 993                ),
 994            ))
 995    }
 996
 997    /// Register a key event listener on the window for the next frame. The type of event
 998    /// is determined by the first parameter of the given listener. When the next frame is rendered
 999    /// the listener will be cleared.
1000    ///
1001    /// This is a fairly low-level method, so prefer using event handlers on elements unless you have
1002    /// a specific need to register a global listener.
1003    pub fn on_key_event<Event: KeyEvent>(
1004        &mut self,
1005        listener: impl Fn(&Event, DispatchPhase, &mut WindowContext) + 'static,
1006    ) {
1007        self.window.next_frame.dispatch_tree.on_key_event(Rc::new(
1008            move |event: &dyn Any, phase, cx: &mut WindowContext<'_>| {
1009                if let Some(event) = event.downcast_ref::<Event>() {
1010                    listener(event, phase, cx)
1011                }
1012            },
1013        ));
1014    }
1015
1016    /// Register an action listener on the window for the next frame. The type of action
1017    /// is determined by the first parameter of the given listener. When the next frame is rendered
1018    /// the listener will be cleared.
1019    ///
1020    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
1021    /// a specific need to register a global listener.
1022    pub fn on_action(
1023        &mut self,
1024        action_type: TypeId,
1025        listener: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
1026    ) {
1027        self.window
1028            .next_frame
1029            .dispatch_tree
1030            .on_action(action_type, Rc::new(listener));
1031    }
1032
1033    /// Determine whether the given action is available along the dispatch path to the currently focused element.
1034    pub fn is_action_available(&self, action: &dyn Action) -> bool {
1035        let target = self
1036            .focused()
1037            .and_then(|focused_handle| {
1038                self.window
1039                    .rendered_frame
1040                    .dispatch_tree
1041                    .focusable_node_id(focused_handle.id)
1042            })
1043            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1044        self.window
1045            .rendered_frame
1046            .dispatch_tree
1047            .is_action_available(action, target)
1048    }
1049
1050    /// The position of the mouse relative to the window.
1051    pub fn mouse_position(&self) -> Point<Pixels> {
1052        self.window.mouse_position
1053    }
1054
1055    /// The current state of the keyboard's modifiers
1056    pub fn modifiers(&self) -> Modifiers {
1057        self.window.modifiers
1058    }
1059
1060    /// Update the cursor style at the platform level.
1061    pub fn set_cursor_style(&mut self, style: CursorStyle) {
1062        let view_id = self.parent_view_id();
1063        self.window.next_frame.cursor_styles.insert(view_id, style);
1064        self.window.next_frame.requested_cursor_style = Some(style);
1065    }
1066
1067    /// Set a tooltip to be rendered for the upcoming frame
1068    pub fn set_tooltip(&mut self, tooltip: AnyTooltip) {
1069        let view_id = self.parent_view_id();
1070        self.window.next_frame.tooltip_request = Some(TooltipRequest { view_id, tooltip });
1071    }
1072
1073    /// Called during painting to track which z-index is on top at each pixel position
1074    pub fn add_opaque_layer(&mut self, bounds: Bounds<Pixels>) {
1075        let stacking_order = self.window.next_frame.z_index_stack.clone();
1076        let view_id = self.parent_view_id();
1077        let depth_map = &mut self.window.next_frame.depth_map;
1078        match depth_map.binary_search_by(|(level, _, _)| stacking_order.cmp(level)) {
1079            Ok(i) | Err(i) => depth_map.insert(i, (stacking_order, view_id, bounds)),
1080        }
1081    }
1082
1083    /// Returns true if there is no opaque layer containing the given point
1084    /// on top of the given level. Layers whose level is an extension of the
1085    /// level are not considered to be on top of the level.
1086    pub fn was_top_layer(&self, point: &Point<Pixels>, level: &StackingOrder) -> bool {
1087        for (opaque_level, _, bounds) in self.window.rendered_frame.depth_map.iter() {
1088            if level >= opaque_level {
1089                break;
1090            }
1091
1092            if bounds.contains(point) && !opaque_level.starts_with(level) {
1093                return false;
1094            }
1095        }
1096        true
1097    }
1098
1099    pub(crate) fn was_top_layer_under_active_drag(
1100        &self,
1101        point: &Point<Pixels>,
1102        level: &StackingOrder,
1103    ) -> bool {
1104        for (opaque_level, _, bounds) in self.window.rendered_frame.depth_map.iter() {
1105            if level >= opaque_level {
1106                break;
1107            }
1108            if opaque_level.starts_with(&[ACTIVE_DRAG_Z_INDEX]) {
1109                continue;
1110            }
1111
1112            if bounds.contains(point) && !opaque_level.starts_with(level) {
1113                return false;
1114            }
1115        }
1116        true
1117    }
1118
1119    /// Called during painting to get the current stacking order.
1120    pub fn stacking_order(&self) -> &StackingOrder {
1121        &self.window.next_frame.z_index_stack
1122    }
1123
1124    /// Paint one or more drop shadows into the scene for the next frame at the current z-index.
1125    pub fn paint_shadows(
1126        &mut self,
1127        bounds: Bounds<Pixels>,
1128        corner_radii: Corners<Pixels>,
1129        shadows: &[BoxShadow],
1130    ) {
1131        let scale_factor = self.scale_factor();
1132        let content_mask = self.content_mask();
1133        let view_id = self.parent_view_id();
1134        let window = &mut *self.window;
1135        for shadow in shadows {
1136            let mut shadow_bounds = bounds;
1137            shadow_bounds.origin += shadow.offset;
1138            shadow_bounds.dilate(shadow.spread_radius);
1139            window.next_frame.scene.insert(
1140                &window.next_frame.z_index_stack,
1141                Shadow {
1142                    view_id: view_id.into(),
1143                    layer_id: 0,
1144                    order: 0,
1145                    bounds: shadow_bounds.scale(scale_factor),
1146                    content_mask: content_mask.scale(scale_factor),
1147                    corner_radii: corner_radii.scale(scale_factor),
1148                    color: shadow.color,
1149                    blur_radius: shadow.blur_radius.scale(scale_factor),
1150                },
1151            );
1152        }
1153    }
1154
1155    /// Paint one or more quads into the scene for the next frame at the current stacking context.
1156    /// Quads are colored rectangular regions with an optional background, border, and corner radius.
1157    /// see [`fill`], [`outline`], and [`quad`] to construct this type.
1158    pub fn paint_quad(&mut self, quad: PaintQuad) {
1159        let scale_factor = self.scale_factor();
1160        let content_mask = self.content_mask();
1161        let view_id = self.parent_view_id();
1162
1163        let window = &mut *self.window;
1164        window.next_frame.scene.insert(
1165            &window.next_frame.z_index_stack,
1166            Quad {
1167                view_id: view_id.into(),
1168                layer_id: 0,
1169                order: 0,
1170                bounds: quad.bounds.scale(scale_factor),
1171                content_mask: content_mask.scale(scale_factor),
1172                background: quad.background,
1173                border_color: quad.border_color,
1174                corner_radii: quad.corner_radii.scale(scale_factor),
1175                border_widths: quad.border_widths.scale(scale_factor),
1176            },
1177        );
1178    }
1179
1180    /// Paint the given `Path` into the scene for the next frame at the current z-index.
1181    pub fn paint_path(&mut self, mut path: Path<Pixels>, color: impl Into<Hsla>) {
1182        let scale_factor = self.scale_factor();
1183        let content_mask = self.content_mask();
1184        let view_id = self.parent_view_id();
1185
1186        path.content_mask = content_mask;
1187        path.color = color.into();
1188        path.view_id = view_id.into();
1189        let window = &mut *self.window;
1190        window
1191            .next_frame
1192            .scene
1193            .insert(&window.next_frame.z_index_stack, path.scale(scale_factor));
1194    }
1195
1196    /// Paint an underline into the scene for the next frame at the current z-index.
1197    pub fn paint_underline(
1198        &mut self,
1199        origin: Point<Pixels>,
1200        width: Pixels,
1201        style: &UnderlineStyle,
1202    ) {
1203        let scale_factor = self.scale_factor();
1204        let height = if style.wavy {
1205            style.thickness * 3.
1206        } else {
1207            style.thickness
1208        };
1209        let bounds = Bounds {
1210            origin,
1211            size: size(width, height),
1212        };
1213        let content_mask = self.content_mask();
1214        let view_id = self.parent_view_id();
1215
1216        let window = &mut *self.window;
1217        window.next_frame.scene.insert(
1218            &window.next_frame.z_index_stack,
1219            Underline {
1220                view_id: view_id.into(),
1221                layer_id: 0,
1222                order: 0,
1223                bounds: bounds.scale(scale_factor),
1224                content_mask: content_mask.scale(scale_factor),
1225                thickness: style.thickness.scale(scale_factor),
1226                color: style.color.unwrap_or_default(),
1227                wavy: style.wavy,
1228            },
1229        );
1230    }
1231
1232    /// Paint a monochrome (non-emoji) glyph into the scene for the next frame at the current z-index.
1233    /// The y component of the origin is the baseline of the glyph.
1234    pub fn paint_glyph(
1235        &mut self,
1236        origin: Point<Pixels>,
1237        font_id: FontId,
1238        glyph_id: GlyphId,
1239        font_size: Pixels,
1240        color: Hsla,
1241    ) -> Result<()> {
1242        let scale_factor = self.scale_factor();
1243        let glyph_origin = origin.scale(scale_factor);
1244        let subpixel_variant = Point {
1245            x: (glyph_origin.x.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
1246            y: (glyph_origin.y.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
1247        };
1248        let params = RenderGlyphParams {
1249            font_id,
1250            glyph_id,
1251            font_size,
1252            subpixel_variant,
1253            scale_factor,
1254            is_emoji: false,
1255        };
1256
1257        let raster_bounds = self.text_system().raster_bounds(&params)?;
1258        if !raster_bounds.is_zero() {
1259            let tile =
1260                self.window
1261                    .sprite_atlas
1262                    .get_or_insert_with(&params.clone().into(), &mut || {
1263                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
1264                        Ok((size, Cow::Owned(bytes)))
1265                    })?;
1266            let bounds = Bounds {
1267                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
1268                size: tile.bounds.size.map(Into::into),
1269            };
1270            let content_mask = self.content_mask().scale(scale_factor);
1271            let view_id = self.parent_view_id();
1272            let window = &mut *self.window;
1273            window.next_frame.scene.insert(
1274                &window.next_frame.z_index_stack,
1275                MonochromeSprite {
1276                    view_id: view_id.into(),
1277                    layer_id: 0,
1278                    order: 0,
1279                    bounds,
1280                    content_mask,
1281                    color,
1282                    tile,
1283                },
1284            );
1285        }
1286        Ok(())
1287    }
1288
1289    /// Paint an emoji glyph into the scene for the next frame at the current z-index.
1290    /// The y component of the origin is the baseline of the glyph.
1291    pub fn paint_emoji(
1292        &mut self,
1293        origin: Point<Pixels>,
1294        font_id: FontId,
1295        glyph_id: GlyphId,
1296        font_size: Pixels,
1297    ) -> Result<()> {
1298        let scale_factor = self.scale_factor();
1299        let glyph_origin = origin.scale(scale_factor);
1300        let params = RenderGlyphParams {
1301            font_id,
1302            glyph_id,
1303            font_size,
1304            // We don't render emojis with subpixel variants.
1305            subpixel_variant: Default::default(),
1306            scale_factor,
1307            is_emoji: true,
1308        };
1309
1310        let raster_bounds = self.text_system().raster_bounds(&params)?;
1311        if !raster_bounds.is_zero() {
1312            let tile =
1313                self.window
1314                    .sprite_atlas
1315                    .get_or_insert_with(&params.clone().into(), &mut || {
1316                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
1317                        Ok((size, Cow::Owned(bytes)))
1318                    })?;
1319            let bounds = Bounds {
1320                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
1321                size: tile.bounds.size.map(Into::into),
1322            };
1323            let content_mask = self.content_mask().scale(scale_factor);
1324            let view_id = self.parent_view_id();
1325            let window = &mut *self.window;
1326
1327            window.next_frame.scene.insert(
1328                &window.next_frame.z_index_stack,
1329                PolychromeSprite {
1330                    view_id: view_id.into(),
1331                    layer_id: 0,
1332                    order: 0,
1333                    bounds,
1334                    corner_radii: Default::default(),
1335                    content_mask,
1336                    tile,
1337                    grayscale: false,
1338                },
1339            );
1340        }
1341        Ok(())
1342    }
1343
1344    /// Paint a monochrome SVG into the scene for the next frame at the current stacking context.
1345    pub fn paint_svg(
1346        &mut self,
1347        bounds: Bounds<Pixels>,
1348        path: SharedString,
1349        color: Hsla,
1350    ) -> Result<()> {
1351        let scale_factor = self.scale_factor();
1352        let bounds = bounds.scale(scale_factor);
1353        // Render the SVG at twice the size to get a higher quality result.
1354        let params = RenderSvgParams {
1355            path,
1356            size: bounds
1357                .size
1358                .map(|pixels| DevicePixels::from((pixels.0 * 2.).ceil() as i32)),
1359        };
1360
1361        let tile =
1362            self.window
1363                .sprite_atlas
1364                .get_or_insert_with(&params.clone().into(), &mut || {
1365                    let bytes = self.svg_renderer.render(&params)?;
1366                    Ok((params.size, Cow::Owned(bytes)))
1367                })?;
1368        let content_mask = self.content_mask().scale(scale_factor);
1369        let view_id = self.parent_view_id();
1370
1371        let window = &mut *self.window;
1372        window.next_frame.scene.insert(
1373            &window.next_frame.z_index_stack,
1374            MonochromeSprite {
1375                view_id: view_id.into(),
1376                layer_id: 0,
1377                order: 0,
1378                bounds,
1379                content_mask,
1380                color,
1381                tile,
1382            },
1383        );
1384
1385        Ok(())
1386    }
1387
1388    /// Paint an image into the scene for the next frame at the current z-index.
1389    pub fn paint_image(
1390        &mut self,
1391        bounds: Bounds<Pixels>,
1392        corner_radii: Corners<Pixels>,
1393        data: Arc<ImageData>,
1394        grayscale: bool,
1395    ) -> Result<()> {
1396        let scale_factor = self.scale_factor();
1397        let bounds = bounds.scale(scale_factor);
1398        let params = RenderImageParams { image_id: data.id };
1399
1400        let tile = self
1401            .window
1402            .sprite_atlas
1403            .get_or_insert_with(&params.clone().into(), &mut || {
1404                Ok((data.size(), Cow::Borrowed(data.as_bytes())))
1405            })?;
1406        let content_mask = self.content_mask().scale(scale_factor);
1407        let corner_radii = corner_radii.scale(scale_factor);
1408        let view_id = self.parent_view_id();
1409
1410        let window = &mut *self.window;
1411        window.next_frame.scene.insert(
1412            &window.next_frame.z_index_stack,
1413            PolychromeSprite {
1414                view_id: view_id.into(),
1415                layer_id: 0,
1416                order: 0,
1417                bounds,
1418                content_mask,
1419                corner_radii,
1420                tile,
1421                grayscale,
1422            },
1423        );
1424        Ok(())
1425    }
1426
1427    /// Paint a surface into the scene for the next frame at the current z-index.
1428    pub fn paint_surface(&mut self, bounds: Bounds<Pixels>, image_buffer: CVImageBuffer) {
1429        let scale_factor = self.scale_factor();
1430        let bounds = bounds.scale(scale_factor);
1431        let content_mask = self.content_mask().scale(scale_factor);
1432        let view_id = self.parent_view_id();
1433        let window = &mut *self.window;
1434        window.next_frame.scene.insert(
1435            &window.next_frame.z_index_stack,
1436            Surface {
1437                view_id: view_id.into(),
1438                layer_id: 0,
1439                order: 0,
1440                bounds,
1441                content_mask,
1442                image_buffer,
1443            },
1444        );
1445    }
1446
1447    pub(crate) fn reuse_view(&mut self) {
1448        let view_id = self.parent_view_id();
1449        let grafted_view_ids = self
1450            .window
1451            .next_frame
1452            .dispatch_tree
1453            .reuse_view(view_id, &mut self.window.rendered_frame.dispatch_tree);
1454        for view_id in grafted_view_ids {
1455            assert!(self.window.next_frame.reused_views.insert(view_id));
1456
1457            // Reuse the previous input handler requested during painting of the reused view.
1458            if self
1459                .window
1460                .rendered_frame
1461                .requested_input_handler
1462                .as_ref()
1463                .map_or(false, |requested| requested.view_id == view_id)
1464            {
1465                self.window.next_frame.requested_input_handler =
1466                    self.window.rendered_frame.requested_input_handler.take();
1467            }
1468
1469            // Reuse the tooltip previously requested during painting of the reused view.
1470            if self
1471                .window
1472                .rendered_frame
1473                .tooltip_request
1474                .as_ref()
1475                .map_or(false, |requested| requested.view_id == view_id)
1476            {
1477                self.window.next_frame.tooltip_request =
1478                    self.window.rendered_frame.tooltip_request.take();
1479            }
1480
1481            // Reuse the cursor styles previously requested during painting of the reused view.
1482            if let Some(style) = self.window.rendered_frame.cursor_styles.remove(&view_id) {
1483                self.window.next_frame.cursor_styles.insert(view_id, style);
1484                self.window.next_frame.requested_cursor_style = Some(style);
1485            }
1486        }
1487    }
1488
1489    /// Draw pixels to the display for this window based on the contents of its scene.
1490    pub(crate) fn draw(&mut self) {
1491        self.window.dirty = false;
1492        self.window.drawing = true;
1493
1494        #[cfg(any(test, feature = "test-support"))]
1495        {
1496            self.window.focus_invalidated = false;
1497        }
1498
1499        if let Some(requested_handler) = self.window.rendered_frame.requested_input_handler.as_mut()
1500        {
1501            requested_handler.handler = self.window.platform_window.take_input_handler();
1502        }
1503
1504        let root_view = self.window.root_view.take().unwrap();
1505
1506        self.with_z_index(0, |cx| {
1507            cx.with_key_dispatch(Some(KeyContext::default()), None, |_, cx| {
1508                for (action_type, action_listeners) in &cx.app.global_action_listeners {
1509                    for action_listener in action_listeners.iter().cloned() {
1510                        cx.window.next_frame.dispatch_tree.on_action(
1511                            *action_type,
1512                            Rc::new(move |action: &dyn Any, phase, cx: &mut WindowContext<'_>| {
1513                                action_listener(action, phase, cx)
1514                            }),
1515                        )
1516                    }
1517                }
1518
1519                let available_space = cx.window.viewport_size.map(Into::into);
1520                root_view.draw(Point::default(), available_space, cx);
1521            })
1522        });
1523
1524        if let Some(active_drag) = self.app.active_drag.take() {
1525            self.with_z_index(ACTIVE_DRAG_Z_INDEX, |cx| {
1526                let offset = cx.mouse_position() - active_drag.cursor_offset;
1527                let available_space = size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1528                active_drag.view.draw(offset, available_space, cx);
1529            });
1530            self.active_drag = Some(active_drag);
1531        } else if let Some(tooltip_request) = self.window.next_frame.tooltip_request.take() {
1532            self.with_z_index(1, |cx| {
1533                let available_space = size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1534                tooltip_request.tooltip.view.draw(
1535                    tooltip_request.tooltip.cursor_offset,
1536                    available_space,
1537                    cx,
1538                );
1539            });
1540            self.window.next_frame.tooltip_request = Some(tooltip_request);
1541        }
1542        self.window.dirty_views.clear();
1543
1544        self.window
1545            .next_frame
1546            .dispatch_tree
1547            .preserve_pending_keystrokes(
1548                &mut self.window.rendered_frame.dispatch_tree,
1549                self.window.focus,
1550            );
1551        self.window.next_frame.focus = self.window.focus;
1552        self.window.next_frame.window_active = self.window.active;
1553        self.window.root_view = Some(root_view);
1554
1555        // Set the cursor only if we're the active window.
1556        let cursor_style = self
1557            .window
1558            .next_frame
1559            .requested_cursor_style
1560            .take()
1561            .unwrap_or(CursorStyle::Arrow);
1562        if self.is_window_active() {
1563            self.platform.set_cursor_style(cursor_style);
1564        }
1565
1566        // Register requested input handler with the platform window.
1567        if let Some(requested_input) = self.window.next_frame.requested_input_handler.as_mut() {
1568            if let Some(handler) = requested_input.handler.take() {
1569                self.window.platform_window.set_input_handler(handler);
1570            }
1571        }
1572
1573        self.window.layout_engine.as_mut().unwrap().clear();
1574        self.text_system()
1575            .finish_frame(&self.window.next_frame.reused_views);
1576        self.window
1577            .next_frame
1578            .finish(&mut self.window.rendered_frame);
1579        ELEMENT_ARENA.with_borrow_mut(|element_arena| element_arena.clear());
1580
1581        let previous_focus_path = self.window.rendered_frame.focus_path();
1582        let previous_window_active = self.window.rendered_frame.window_active;
1583        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1584        self.window.next_frame.clear();
1585        let current_focus_path = self.window.rendered_frame.focus_path();
1586        let current_window_active = self.window.rendered_frame.window_active;
1587
1588        if previous_focus_path != current_focus_path
1589            || previous_window_active != current_window_active
1590        {
1591            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1592                self.window
1593                    .focus_lost_listeners
1594                    .clone()
1595                    .retain(&(), |listener| listener(self));
1596            }
1597
1598            let event = FocusEvent {
1599                previous_focus_path: if previous_window_active {
1600                    previous_focus_path
1601                } else {
1602                    Default::default()
1603                },
1604                current_focus_path: if current_window_active {
1605                    current_focus_path
1606                } else {
1607                    Default::default()
1608                },
1609            };
1610            self.window
1611                .focus_listeners
1612                .clone()
1613                .retain(&(), |listener| listener(&event, self));
1614        }
1615
1616        self.window
1617            .platform_window
1618            .draw(&self.window.rendered_frame.scene);
1619        self.window.refreshing = false;
1620        self.window.drawing = false;
1621    }
1622
1623    /// Dispatch a mouse or keyboard event on the window.
1624    pub fn dispatch_event(&mut self, event: PlatformInput) -> bool {
1625        // Handlers may set this to false by calling `stop_propagation`.
1626        self.app.propagate_event = true;
1627        // Handlers may set this to true by calling `prevent_default`.
1628        self.window.default_prevented = false;
1629
1630        let event = match event {
1631            // Track the mouse position with our own state, since accessing the platform
1632            // API for the mouse position can only occur on the main thread.
1633            PlatformInput::MouseMove(mouse_move) => {
1634                self.window.mouse_position = mouse_move.position;
1635                self.window.modifiers = mouse_move.modifiers;
1636                PlatformInput::MouseMove(mouse_move)
1637            }
1638            PlatformInput::MouseDown(mouse_down) => {
1639                self.window.mouse_position = mouse_down.position;
1640                self.window.modifiers = mouse_down.modifiers;
1641                PlatformInput::MouseDown(mouse_down)
1642            }
1643            PlatformInput::MouseUp(mouse_up) => {
1644                self.window.mouse_position = mouse_up.position;
1645                self.window.modifiers = mouse_up.modifiers;
1646                PlatformInput::MouseUp(mouse_up)
1647            }
1648            PlatformInput::MouseExited(mouse_exited) => {
1649                self.window.modifiers = mouse_exited.modifiers;
1650                PlatformInput::MouseExited(mouse_exited)
1651            }
1652            PlatformInput::ModifiersChanged(modifiers_changed) => {
1653                self.window.modifiers = modifiers_changed.modifiers;
1654                PlatformInput::ModifiersChanged(modifiers_changed)
1655            }
1656            PlatformInput::ScrollWheel(scroll_wheel) => {
1657                self.window.mouse_position = scroll_wheel.position;
1658                self.window.modifiers = scroll_wheel.modifiers;
1659                PlatformInput::ScrollWheel(scroll_wheel)
1660            }
1661            // Translate dragging and dropping of external files from the operating system
1662            // to internal drag and drop events.
1663            PlatformInput::FileDrop(file_drop) => match file_drop {
1664                FileDropEvent::Entered { position, paths } => {
1665                    self.window.mouse_position = position;
1666                    if self.active_drag.is_none() {
1667                        self.active_drag = Some(AnyDrag {
1668                            value: Box::new(paths.clone()),
1669                            view: self.new_view(|_| paths).into(),
1670                            cursor_offset: position,
1671                        });
1672                    }
1673                    PlatformInput::MouseMove(MouseMoveEvent {
1674                        position,
1675                        pressed_button: Some(MouseButton::Left),
1676                        modifiers: Modifiers::default(),
1677                    })
1678                }
1679                FileDropEvent::Pending { position } => {
1680                    self.window.mouse_position = position;
1681                    PlatformInput::MouseMove(MouseMoveEvent {
1682                        position,
1683                        pressed_button: Some(MouseButton::Left),
1684                        modifiers: Modifiers::default(),
1685                    })
1686                }
1687                FileDropEvent::Submit { position } => {
1688                    self.activate(true);
1689                    self.window.mouse_position = position;
1690                    PlatformInput::MouseUp(MouseUpEvent {
1691                        button: MouseButton::Left,
1692                        position,
1693                        modifiers: Modifiers::default(),
1694                        click_count: 1,
1695                    })
1696                }
1697                FileDropEvent::Exited => PlatformInput::MouseUp(MouseUpEvent {
1698                    button: MouseButton::Left,
1699                    position: Point::default(),
1700                    modifiers: Modifiers::default(),
1701                    click_count: 1,
1702                }),
1703            },
1704            PlatformInput::KeyDown(_) | PlatformInput::KeyUp(_) => event,
1705        };
1706
1707        if let Some(any_mouse_event) = event.mouse_event() {
1708            self.dispatch_mouse_event(any_mouse_event);
1709        } else if let Some(any_key_event) = event.keyboard_event() {
1710            self.dispatch_key_event(any_key_event);
1711        }
1712
1713        !self.app.propagate_event
1714    }
1715
1716    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1717        if let Some(mut handlers) = self
1718            .window
1719            .rendered_frame
1720            .mouse_listeners
1721            .remove(&event.type_id())
1722        {
1723            // Because handlers may add other handlers, we sort every time.
1724            handlers.sort_by(|(a, _, _), (b, _, _)| a.cmp(b));
1725
1726            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1727            // special purposes, such as detecting events outside of a given Bounds.
1728            for (_, _, handler) in &mut handlers {
1729                handler(event, DispatchPhase::Capture, self);
1730                if !self.app.propagate_event {
1731                    break;
1732                }
1733            }
1734
1735            // Bubble phase, where most normal handlers do their work.
1736            if self.app.propagate_event {
1737                for (_, _, handler) in handlers.iter_mut().rev() {
1738                    handler(event, DispatchPhase::Bubble, self);
1739                    if !self.app.propagate_event {
1740                        break;
1741                    }
1742                }
1743            }
1744
1745            self.window
1746                .rendered_frame
1747                .mouse_listeners
1748                .insert(event.type_id(), handlers);
1749        }
1750
1751        if self.app.propagate_event && self.has_active_drag() {
1752            if event.is::<MouseMoveEvent>() {
1753                // If this was a mouse move event, redraw the window so that the
1754                // active drag can follow the mouse cursor.
1755                self.refresh();
1756            } else if event.is::<MouseUpEvent>() {
1757                // If this was a mouse up event, cancel the active drag and redraw
1758                // the window.
1759                self.active_drag = None;
1760                self.refresh();
1761            }
1762        }
1763    }
1764
1765    fn dispatch_key_event(&mut self, event: &dyn Any) {
1766        let node_id = self
1767            .window
1768            .focus
1769            .and_then(|focus_id| {
1770                self.window
1771                    .rendered_frame
1772                    .dispatch_tree
1773                    .focusable_node_id(focus_id)
1774            })
1775            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1776
1777        let dispatch_path = self
1778            .window
1779            .rendered_frame
1780            .dispatch_tree
1781            .dispatch_path(node_id);
1782
1783        let mut actions: Vec<Box<dyn Action>> = Vec::new();
1784
1785        let mut context_stack: SmallVec<[KeyContext; 16]> = SmallVec::new();
1786        for node_id in &dispatch_path {
1787            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1788
1789            if let Some(context) = node.context.clone() {
1790                context_stack.push(context);
1791            }
1792        }
1793
1794        for node_id in dispatch_path.iter().rev() {
1795            // Match keystrokes
1796            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1797            if node.context.is_some() {
1798                if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1799                    let mut new_actions = self
1800                        .window
1801                        .rendered_frame
1802                        .dispatch_tree
1803                        .dispatch_key(&key_down_event.keystroke, &context_stack);
1804                    actions.append(&mut new_actions);
1805                }
1806
1807                context_stack.pop();
1808            }
1809        }
1810
1811        if !actions.is_empty() {
1812            self.clear_pending_keystrokes();
1813        }
1814
1815        self.propagate_event = true;
1816        for action in actions {
1817            self.dispatch_action_on_node(node_id, action.boxed_clone());
1818            if !self.propagate_event {
1819                self.dispatch_keystroke_observers(event, Some(action));
1820                return;
1821            }
1822        }
1823
1824        // Capture phase
1825        for node_id in &dispatch_path {
1826            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1827
1828            for key_listener in node.key_listeners.clone() {
1829                key_listener(event, DispatchPhase::Capture, self);
1830                if !self.propagate_event {
1831                    return;
1832                }
1833            }
1834        }
1835
1836        // Bubble phase
1837        for node_id in dispatch_path.iter().rev() {
1838            // Handle low level key events
1839            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1840            for key_listener in node.key_listeners.clone() {
1841                key_listener(event, DispatchPhase::Bubble, self);
1842                if !self.propagate_event {
1843                    return;
1844                }
1845            }
1846        }
1847
1848        self.dispatch_keystroke_observers(event, None);
1849    }
1850
1851    /// Determine whether a potential multi-stroke key binding is in progress on this window.
1852    pub fn has_pending_keystrokes(&self) -> bool {
1853        self.window
1854            .rendered_frame
1855            .dispatch_tree
1856            .has_pending_keystrokes()
1857    }
1858
1859    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: Box<dyn Action>) {
1860        let dispatch_path = self
1861            .window
1862            .rendered_frame
1863            .dispatch_tree
1864            .dispatch_path(node_id);
1865
1866        // Capture phase
1867        for node_id in &dispatch_path {
1868            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1869            for DispatchActionListener {
1870                action_type,
1871                listener,
1872            } in node.action_listeners.clone()
1873            {
1874                let any_action = action.as_any();
1875                if action_type == any_action.type_id() {
1876                    listener(any_action, DispatchPhase::Capture, self);
1877                    if !self.propagate_event {
1878                        return;
1879                    }
1880                }
1881            }
1882        }
1883        // Bubble phase
1884        for node_id in dispatch_path.iter().rev() {
1885            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1886            for DispatchActionListener {
1887                action_type,
1888                listener,
1889            } in node.action_listeners.clone()
1890            {
1891                let any_action = action.as_any();
1892                if action_type == any_action.type_id() {
1893                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1894                    listener(any_action, DispatchPhase::Bubble, self);
1895                    if !self.propagate_event {
1896                        return;
1897                    }
1898                }
1899            }
1900        }
1901    }
1902
1903    /// Register the given handler to be invoked whenever the global of the given type
1904    /// is updated.
1905    pub fn observe_global<G: 'static>(
1906        &mut self,
1907        f: impl Fn(&mut WindowContext<'_>) + 'static,
1908    ) -> Subscription {
1909        let window_handle = self.window.handle;
1910        let (subscription, activate) = self.global_observers.insert(
1911            TypeId::of::<G>(),
1912            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1913        );
1914        self.app.defer(move |_| activate());
1915        subscription
1916    }
1917
1918    /// Focus the current window and bring it to the foreground at the platform level.
1919    pub fn activate_window(&self) {
1920        self.window.platform_window.activate();
1921    }
1922
1923    /// Minimize the current window at the platform level.
1924    pub fn minimize_window(&self) {
1925        self.window.platform_window.minimize();
1926    }
1927
1928    /// Toggle full screen status on the current window at the platform level.
1929    pub fn toggle_full_screen(&self) {
1930        self.window.platform_window.toggle_full_screen();
1931    }
1932
1933    /// Present a platform dialog.
1934    /// The provided message will be presented, along with buttons for each answer.
1935    /// When a button is clicked, the returned Receiver will receive the index of the clicked button.
1936    pub fn prompt(
1937        &self,
1938        level: PromptLevel,
1939        message: &str,
1940        answers: &[&str],
1941    ) -> oneshot::Receiver<usize> {
1942        self.window.platform_window.prompt(level, message, answers)
1943    }
1944
1945    /// Returns all available actions for the focused element.
1946    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1947        let node_id = self
1948            .window
1949            .focus
1950            .and_then(|focus_id| {
1951                self.window
1952                    .rendered_frame
1953                    .dispatch_tree
1954                    .focusable_node_id(focus_id)
1955            })
1956            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1957
1958        self.window
1959            .rendered_frame
1960            .dispatch_tree
1961            .available_actions(node_id)
1962    }
1963
1964    /// Returns key bindings that invoke the given action on the currently focused element.
1965    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1966        self.window
1967            .rendered_frame
1968            .dispatch_tree
1969            .bindings_for_action(
1970                action,
1971                &self.window.rendered_frame.dispatch_tree.context_stack,
1972            )
1973    }
1974
1975    /// Returns any bindings that would invoke the given action on the given focus handle if it were focused.
1976    pub fn bindings_for_action_in(
1977        &self,
1978        action: &dyn Action,
1979        focus_handle: &FocusHandle,
1980    ) -> Vec<KeyBinding> {
1981        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1982
1983        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1984            return vec![];
1985        };
1986        let context_stack = dispatch_tree
1987            .dispatch_path(node_id)
1988            .into_iter()
1989            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1990            .collect();
1991        dispatch_tree.bindings_for_action(action, &context_stack)
1992    }
1993
1994    /// Returns a generic event listener that invokes the given listener with the view and context associated with the given view handle.
1995    pub fn listener_for<V: Render, E>(
1996        &self,
1997        view: &View<V>,
1998        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1999    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2000        let view = view.downgrade();
2001        move |e: &E, cx: &mut WindowContext| {
2002            view.update(cx, |view, cx| f(view, e, cx)).ok();
2003        }
2004    }
2005
2006    /// Returns a generic handler that invokes the given handler with the view and context associated with the given view handle.
2007    pub fn handler_for<V: Render>(
2008        &self,
2009        view: &View<V>,
2010        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
2011    ) -> impl Fn(&mut WindowContext) {
2012        let view = view.downgrade();
2013        move |cx: &mut WindowContext| {
2014            view.update(cx, |view, cx| f(view, cx)).ok();
2015        }
2016    }
2017
2018    /// Invoke the given function with the given focus handle present on the key dispatch stack.
2019    /// If you want an element to participate in key dispatch, use this method to push its key context and focus handle into the stack during paint.
2020    pub fn with_key_dispatch<R>(
2021        &mut self,
2022        context: Option<KeyContext>,
2023        focus_handle: Option<FocusHandle>,
2024        f: impl FnOnce(Option<FocusHandle>, &mut Self) -> R,
2025    ) -> R {
2026        let window = &mut self.window;
2027        let focus_id = focus_handle.as_ref().map(|handle| handle.id);
2028        window
2029            .next_frame
2030            .dispatch_tree
2031            .push_node(context.clone(), focus_id, None);
2032
2033        let result = f(focus_handle, self);
2034
2035        self.window.next_frame.dispatch_tree.pop_node();
2036
2037        result
2038    }
2039
2040    /// Invoke the given function with the given view id present on the view stack.
2041    /// This is a fairly low-level method used to layout views.
2042    pub fn with_view_id<R>(&mut self, view_id: EntityId, f: impl FnOnce(&mut Self) -> R) -> R {
2043        let text_system = self.text_system().clone();
2044        text_system.with_view(view_id, || {
2045            if self.window.next_frame.view_stack.last() == Some(&view_id) {
2046                return f(self);
2047            } else {
2048                self.window.next_frame.view_stack.push(view_id);
2049                let result = f(self);
2050                self.window.next_frame.view_stack.pop();
2051                result
2052            }
2053        })
2054    }
2055
2056    /// Invoke the given function with the given view id present on the view stack.
2057    /// This is a fairly low-level method used to paint views.
2058    pub fn paint_view<R>(&mut self, view_id: EntityId, f: impl FnOnce(&mut Self) -> R) -> R {
2059        let text_system = self.text_system().clone();
2060        text_system.with_view(view_id, || {
2061            if self.window.next_frame.view_stack.last() == Some(&view_id) {
2062                return f(self);
2063            } else {
2064                self.window.next_frame.view_stack.push(view_id);
2065                self.window
2066                    .next_frame
2067                    .dispatch_tree
2068                    .push_node(None, None, Some(view_id));
2069                let result = f(self);
2070                self.window.next_frame.dispatch_tree.pop_node();
2071                self.window.next_frame.view_stack.pop();
2072                result
2073            }
2074        })
2075    }
2076
2077    /// Update or initialize state for an element with the given id that lives across multiple
2078    /// frames. If an element with this id existed in the rendered frame, its state will be passed
2079    /// to the given closure. The state returned by the closure will be stored so it can be referenced
2080    /// when drawing the next frame.
2081    pub(crate) fn with_element_state<S, R>(
2082        &mut self,
2083        id: ElementId,
2084        f: impl FnOnce(Option<S>, &mut Self) -> (R, S),
2085    ) -> R
2086    where
2087        S: 'static,
2088    {
2089        self.with_element_id(Some(id), |cx| {
2090            let global_id = cx.window().element_id_stack.clone();
2091
2092            if let Some(any) = cx
2093                .window_mut()
2094                .next_frame
2095                .element_states
2096                .remove(&global_id)
2097                .or_else(|| {
2098                    cx.window_mut()
2099                        .rendered_frame
2100                        .element_states
2101                        .remove(&global_id)
2102                })
2103            {
2104                let ElementStateBox {
2105                    inner,
2106                    parent_view_id,
2107                    #[cfg(debug_assertions)]
2108                    type_name
2109                } = any;
2110                // Using the extra inner option to avoid needing to reallocate a new box.
2111                let mut state_box = inner
2112                    .downcast::<Option<S>>()
2113                    .map_err(|_| {
2114                        #[cfg(debug_assertions)]
2115                        {
2116                            anyhow!(
2117                                "invalid element state type for id, requested_type {:?}, actual type: {:?}",
2118                                std::any::type_name::<S>(),
2119                                type_name
2120                            )
2121                        }
2122
2123                        #[cfg(not(debug_assertions))]
2124                        {
2125                            anyhow!(
2126                                "invalid element state type for id, requested_type {:?}",
2127                                std::any::type_name::<S>(),
2128                            )
2129                        }
2130                    })
2131                    .unwrap();
2132
2133                // Actual: Option<AnyElement> <- View
2134                // Requested: () <- AnyElement
2135                let state = state_box
2136                    .take()
2137                    .expect("element state is already on the stack");
2138                let (result, state) = f(Some(state), cx);
2139                state_box.replace(state);
2140                cx.window_mut()
2141                    .next_frame
2142                    .element_states
2143                    .insert(global_id, ElementStateBox {
2144                        inner: state_box,
2145                        parent_view_id,
2146                        #[cfg(debug_assertions)]
2147                        type_name
2148                    });
2149                result
2150            } else {
2151                let (result, state) = f(None, cx);
2152                let parent_view_id = cx.parent_view_id();
2153                cx.window_mut()
2154                    .next_frame
2155                    .element_states
2156                    .insert(global_id,
2157                        ElementStateBox {
2158                            inner: Box::new(Some(state)),
2159                            parent_view_id,
2160                            #[cfg(debug_assertions)]
2161                            type_name: std::any::type_name::<S>()
2162                        }
2163
2164                    );
2165                result
2166            }
2167        })
2168    }
2169
2170    fn parent_view_id(&self) -> EntityId {
2171        *self
2172            .window
2173            .next_frame
2174            .view_stack
2175            .last()
2176            .expect("a view should always be on the stack while drawing")
2177    }
2178
2179    /// Set an input handler, such as [`ElementInputHandler`][element_input_handler], which interfaces with the
2180    /// platform to receive textual input with proper integration with concerns such
2181    /// as IME interactions. This handler will be active for the upcoming frame until the following frame is
2182    /// rendered.
2183    ///
2184    /// [element_input_handler]: crate::ElementInputHandler
2185    pub fn handle_input(
2186        &mut self,
2187        focus_handle: &FocusHandle,
2188        input_handler: impl PlatformInputHandler,
2189    ) {
2190        if focus_handle.is_focused(self) {
2191            let view_id = self.parent_view_id();
2192            self.window.next_frame.requested_input_handler = Some(RequestedInputHandler {
2193                view_id,
2194                handler: Some(Box::new(input_handler)),
2195            })
2196        }
2197    }
2198
2199    /// Register a callback that can interrupt the closing of the current window based the returned boolean.
2200    /// If the callback returns false, the window won't be closed.
2201    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
2202        let mut this = self.to_async();
2203        self.window
2204            .platform_window
2205            .on_should_close(Box::new(move || {
2206                this.update(|_, cx| {
2207                    // Ensure that the window is removed from the app if it's been closed
2208                    // by always pre-empting the system close event.
2209                    if f(cx) {
2210                        cx.remove_window();
2211                    }
2212                    false
2213                })
2214                .unwrap_or(true)
2215            }))
2216    }
2217}
2218
2219impl Context for WindowContext<'_> {
2220    type Result<T> = T;
2221
2222    fn new_model<T>(&mut self, build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T) -> Model<T>
2223    where
2224        T: 'static,
2225    {
2226        let slot = self.app.entities.reserve();
2227        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
2228        self.entities.insert(slot, model)
2229    }
2230
2231    fn update_model<T: 'static, R>(
2232        &mut self,
2233        model: &Model<T>,
2234        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2235    ) -> R {
2236        let mut entity = self.entities.lease(model);
2237        let result = update(
2238            &mut *entity,
2239            &mut ModelContext::new(&mut *self.app, model.downgrade()),
2240        );
2241        self.entities.end_lease(entity);
2242        result
2243    }
2244
2245    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2246    where
2247        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2248    {
2249        if window == self.window.handle {
2250            let root_view = self.window.root_view.clone().unwrap();
2251            Ok(update(root_view, self))
2252        } else {
2253            window.update(self.app, update)
2254        }
2255    }
2256
2257    fn read_model<T, R>(
2258        &self,
2259        handle: &Model<T>,
2260        read: impl FnOnce(&T, &AppContext) -> R,
2261    ) -> Self::Result<R>
2262    where
2263        T: 'static,
2264    {
2265        let entity = self.entities.read(handle);
2266        read(entity, &*self.app)
2267    }
2268
2269    fn read_window<T, R>(
2270        &self,
2271        window: &WindowHandle<T>,
2272        read: impl FnOnce(View<T>, &AppContext) -> R,
2273    ) -> Result<R>
2274    where
2275        T: 'static,
2276    {
2277        if window.any_handle == self.window.handle {
2278            let root_view = self
2279                .window
2280                .root_view
2281                .clone()
2282                .unwrap()
2283                .downcast::<T>()
2284                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2285            Ok(read(root_view, self))
2286        } else {
2287            self.app.read_window(window, read)
2288        }
2289    }
2290}
2291
2292impl VisualContext for WindowContext<'_> {
2293    fn new_view<V>(
2294        &mut self,
2295        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
2296    ) -> Self::Result<View<V>>
2297    where
2298        V: 'static + Render,
2299    {
2300        let slot = self.app.entities.reserve();
2301        let view = View {
2302            model: slot.clone(),
2303        };
2304        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
2305        let entity = build_view_state(&mut cx);
2306        cx.entities.insert(slot, entity);
2307
2308        cx.new_view_observers
2309            .clone()
2310            .retain(&TypeId::of::<V>(), |observer| {
2311                let any_view = AnyView::from(view.clone());
2312                (observer)(any_view, self);
2313                true
2314            });
2315
2316        view
2317    }
2318
2319    /// Update the given view. Prefer calling `View::update` instead, which calls this method.
2320    fn update_view<T: 'static, R>(
2321        &mut self,
2322        view: &View<T>,
2323        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
2324    ) -> Self::Result<R> {
2325        let mut lease = self.app.entities.lease(&view.model);
2326        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, view);
2327        let result = update(&mut *lease, &mut cx);
2328        cx.app.entities.end_lease(lease);
2329        result
2330    }
2331
2332    fn replace_root_view<V>(
2333        &mut self,
2334        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
2335    ) -> Self::Result<View<V>>
2336    where
2337        V: 'static + Render,
2338    {
2339        let view = self.new_view(build_view);
2340        self.window.root_view = Some(view.clone().into());
2341        self.refresh();
2342        view
2343    }
2344
2345    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
2346        self.update_view(view, |view, cx| {
2347            view.focus_handle(cx).clone().focus(cx);
2348        })
2349    }
2350
2351    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
2352    where
2353        V: ManagedView,
2354    {
2355        self.update_view(view, |_, cx| cx.emit(DismissEvent))
2356    }
2357}
2358
2359impl<'a> std::ops::Deref for WindowContext<'a> {
2360    type Target = AppContext;
2361
2362    fn deref(&self) -> &Self::Target {
2363        self.app
2364    }
2365}
2366
2367impl<'a> std::ops::DerefMut for WindowContext<'a> {
2368    fn deref_mut(&mut self) -> &mut Self::Target {
2369        self.app
2370    }
2371}
2372
2373impl<'a> Borrow<AppContext> for WindowContext<'a> {
2374    fn borrow(&self) -> &AppContext {
2375        self.app
2376    }
2377}
2378
2379impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
2380    fn borrow_mut(&mut self) -> &mut AppContext {
2381        self.app
2382    }
2383}
2384
2385/// This trait contains functionality that is shared across [`ViewContext`] and [`WindowContext`]
2386pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
2387    #[doc(hidden)]
2388    fn app_mut(&mut self) -> &mut AppContext {
2389        self.borrow_mut()
2390    }
2391
2392    #[doc(hidden)]
2393    fn app(&self) -> &AppContext {
2394        self.borrow()
2395    }
2396
2397    #[doc(hidden)]
2398    fn window(&self) -> &Window {
2399        self.borrow()
2400    }
2401
2402    #[doc(hidden)]
2403    fn window_mut(&mut self) -> &mut Window {
2404        self.borrow_mut()
2405    }
2406
2407    /// Pushes the given element id onto the global stack and invokes the given closure
2408    /// with a `GlobalElementId`, which disambiguates the given id in the context of its ancestor
2409    /// ids. Because elements are discarded and recreated on each frame, the `GlobalElementId` is
2410    /// used to associate state with identified elements across separate frames.
2411    fn with_element_id<R>(
2412        &mut self,
2413        id: Option<impl Into<ElementId>>,
2414        f: impl FnOnce(&mut Self) -> R,
2415    ) -> R {
2416        if let Some(id) = id.map(Into::into) {
2417            let window = self.window_mut();
2418            window.element_id_stack.push(id);
2419            let result = f(self);
2420            let window: &mut Window = self.borrow_mut();
2421            window.element_id_stack.pop();
2422            result
2423        } else {
2424            f(self)
2425        }
2426    }
2427
2428    /// Invoke the given function with the given content mask after intersecting it
2429    /// with the current mask.
2430    fn with_content_mask<R>(
2431        &mut self,
2432        mask: Option<ContentMask<Pixels>>,
2433        f: impl FnOnce(&mut Self) -> R,
2434    ) -> R {
2435        if let Some(mask) = mask {
2436            let mask = mask.intersect(&self.content_mask());
2437            self.window_mut().next_frame.content_mask_stack.push(mask);
2438            let result = f(self);
2439            self.window_mut().next_frame.content_mask_stack.pop();
2440            result
2441        } else {
2442            f(self)
2443        }
2444    }
2445
2446    /// Invoke the given function with the content mask reset to that
2447    /// of the window.
2448    fn break_content_mask<R>(&mut self, f: impl FnOnce(&mut Self) -> R) -> R {
2449        let mask = ContentMask {
2450            bounds: Bounds {
2451                origin: Point::default(),
2452                size: self.window().viewport_size,
2453            },
2454        };
2455        let new_stacking_order_id =
2456            post_inc(&mut self.window_mut().next_frame.next_stacking_order_id);
2457        let new_root_z_index = post_inc(&mut self.window_mut().next_frame.next_root_z_index);
2458        let old_stacking_order = mem::take(&mut self.window_mut().next_frame.z_index_stack);
2459        self.window_mut().next_frame.z_index_stack.id = new_stacking_order_id;
2460        self.window_mut()
2461            .next_frame
2462            .z_index_stack
2463            .push(new_root_z_index);
2464        self.window_mut().next_frame.content_mask_stack.push(mask);
2465        let result = f(self);
2466        self.window_mut().next_frame.content_mask_stack.pop();
2467        self.window_mut().next_frame.z_index_stack = old_stacking_order;
2468        result
2469    }
2470
2471    /// Called during painting to invoke the given closure in a new stacking context. The given
2472    /// z-index is interpreted relative to the previous call to `stack`.
2473    fn with_z_index<R>(&mut self, z_index: u8, f: impl FnOnce(&mut Self) -> R) -> R {
2474        let new_stacking_order_id =
2475            post_inc(&mut self.window_mut().next_frame.next_stacking_order_id);
2476        let old_stacking_order_id = mem::replace(
2477            &mut self.window_mut().next_frame.z_index_stack.id,
2478            new_stacking_order_id,
2479        );
2480        self.window_mut().next_frame.z_index_stack.id = new_stacking_order_id;
2481        self.window_mut().next_frame.z_index_stack.push(z_index);
2482        let result = f(self);
2483        self.window_mut().next_frame.z_index_stack.id = old_stacking_order_id;
2484        self.window_mut().next_frame.z_index_stack.pop();
2485        result
2486    }
2487
2488    /// Update the global element offset relative to the current offset. This is used to implement
2489    /// scrolling.
2490    fn with_element_offset<R>(
2491        &mut self,
2492        offset: Point<Pixels>,
2493        f: impl FnOnce(&mut Self) -> R,
2494    ) -> R {
2495        if offset.is_zero() {
2496            return f(self);
2497        };
2498
2499        let abs_offset = self.element_offset() + offset;
2500        self.with_absolute_element_offset(abs_offset, f)
2501    }
2502
2503    /// Update the global element offset based on the given offset. This is used to implement
2504    /// drag handles and other manual painting of elements.
2505    fn with_absolute_element_offset<R>(
2506        &mut self,
2507        offset: Point<Pixels>,
2508        f: impl FnOnce(&mut Self) -> R,
2509    ) -> R {
2510        self.window_mut()
2511            .next_frame
2512            .element_offset_stack
2513            .push(offset);
2514        let result = f(self);
2515        self.window_mut().next_frame.element_offset_stack.pop();
2516        result
2517    }
2518
2519    /// Obtain the current element offset.
2520    fn element_offset(&self) -> Point<Pixels> {
2521        self.window()
2522            .next_frame
2523            .element_offset_stack
2524            .last()
2525            .copied()
2526            .unwrap_or_default()
2527    }
2528
2529    /// Obtain the current content mask.
2530    fn content_mask(&self) -> ContentMask<Pixels> {
2531        self.window()
2532            .next_frame
2533            .content_mask_stack
2534            .last()
2535            .cloned()
2536            .unwrap_or_else(|| ContentMask {
2537                bounds: Bounds {
2538                    origin: Point::default(),
2539                    size: self.window().viewport_size,
2540                },
2541            })
2542    }
2543
2544    /// The size of an em for the base font of the application. Adjusting this value allows the
2545    /// UI to scale, just like zooming a web page.
2546    fn rem_size(&self) -> Pixels {
2547        self.window().rem_size
2548    }
2549}
2550
2551impl Borrow<Window> for WindowContext<'_> {
2552    fn borrow(&self) -> &Window {
2553        self.window
2554    }
2555}
2556
2557impl BorrowMut<Window> for WindowContext<'_> {
2558    fn borrow_mut(&mut self) -> &mut Window {
2559        self.window
2560    }
2561}
2562
2563impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
2564
2565/// Provides access to application state that is specialized for a particular [`View`].
2566/// Allows you to interact with focus, emit events, etc.
2567/// ViewContext also derefs to [`WindowContext`], giving you access to all of its methods as well.
2568/// When you call [`View::update`], you're passed a `&mut V` and an `&mut ViewContext<V>`.
2569pub struct ViewContext<'a, V> {
2570    window_cx: WindowContext<'a>,
2571    view: &'a View<V>,
2572}
2573
2574impl<V> Borrow<AppContext> for ViewContext<'_, V> {
2575    fn borrow(&self) -> &AppContext {
2576        &*self.window_cx.app
2577    }
2578}
2579
2580impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
2581    fn borrow_mut(&mut self) -> &mut AppContext {
2582        &mut *self.window_cx.app
2583    }
2584}
2585
2586impl<V> Borrow<Window> for ViewContext<'_, V> {
2587    fn borrow(&self) -> &Window {
2588        &*self.window_cx.window
2589    }
2590}
2591
2592impl<V> BorrowMut<Window> for ViewContext<'_, V> {
2593    fn borrow_mut(&mut self) -> &mut Window {
2594        &mut *self.window_cx.window
2595    }
2596}
2597
2598impl<'a, V: 'static> ViewContext<'a, V> {
2599    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
2600        Self {
2601            window_cx: WindowContext::new(app, window),
2602            view,
2603        }
2604    }
2605
2606    /// Get the entity_id of this view.
2607    pub fn entity_id(&self) -> EntityId {
2608        self.view.entity_id()
2609    }
2610
2611    /// Get the view pointer underlying this context.
2612    pub fn view(&self) -> &View<V> {
2613        self.view
2614    }
2615
2616    /// Get the model underlying this view.
2617    pub fn model(&self) -> &Model<V> {
2618        &self.view.model
2619    }
2620
2621    /// Access the underlying window context.
2622    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2623        &mut self.window_cx
2624    }
2625
2626    /// Set a given callback to be run on the next frame.
2627    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
2628    where
2629        V: 'static,
2630    {
2631        let view = self.view().clone();
2632        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
2633    }
2634
2635    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
2636    /// that are currently on the stack to be returned to the app.
2637    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
2638        let view = self.view().downgrade();
2639        self.window_cx.defer(move |cx| {
2640            view.update(cx, f).ok();
2641        });
2642    }
2643
2644    /// Observe another model or view for changes to its state, as tracked by [`ModelContext::notify`].
2645    pub fn observe<V2, E>(
2646        &mut self,
2647        entity: &E,
2648        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
2649    ) -> Subscription
2650    where
2651        V2: 'static,
2652        V: 'static,
2653        E: Entity<V2>,
2654    {
2655        let view = self.view().downgrade();
2656        let entity_id = entity.entity_id();
2657        let entity = entity.downgrade();
2658        let window_handle = self.window.handle;
2659        let (subscription, activate) = self.app.observers.insert(
2660            entity_id,
2661            Box::new(move |cx| {
2662                window_handle
2663                    .update(cx, |_, cx| {
2664                        if let Some(handle) = E::upgrade_from(&entity) {
2665                            view.update(cx, |this, cx| on_notify(this, handle, cx))
2666                                .is_ok()
2667                        } else {
2668                            false
2669                        }
2670                    })
2671                    .unwrap_or(false)
2672            }),
2673        );
2674        self.app.defer(move |_| activate());
2675        subscription
2676    }
2677
2678    /// Subscribe to events emitted by another model or view.
2679    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
2680    /// The callback will be invoked with a reference to the current view, a handle to the emitting entity (either a [`View`] or [`Model`]), the event, and a view context for the current view.
2681    pub fn subscribe<V2, E, Evt>(
2682        &mut self,
2683        entity: &E,
2684        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2685    ) -> Subscription
2686    where
2687        V2: EventEmitter<Evt>,
2688        E: Entity<V2>,
2689        Evt: 'static,
2690    {
2691        let view = self.view().downgrade();
2692        let entity_id = entity.entity_id();
2693        let handle = entity.downgrade();
2694        let window_handle = self.window.handle;
2695        let (subscription, activate) = self.app.event_listeners.insert(
2696            entity_id,
2697            (
2698                TypeId::of::<Evt>(),
2699                Box::new(move |event, cx| {
2700                    window_handle
2701                        .update(cx, |_, cx| {
2702                            if let Some(handle) = E::upgrade_from(&handle) {
2703                                let event = event.downcast_ref().expect("invalid event type");
2704                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2705                                    .is_ok()
2706                            } else {
2707                                false
2708                            }
2709                        })
2710                        .unwrap_or(false)
2711                }),
2712            ),
2713        );
2714        self.app.defer(move |_| activate());
2715        subscription
2716    }
2717
2718    /// Register a callback to be invoked when the view is released.
2719    ///
2720    /// The callback receives a handle to the view's window. This handle may be
2721    /// invalid, if the window was closed before the view was released.
2722    pub fn on_release(
2723        &mut self,
2724        on_release: impl FnOnce(&mut V, AnyWindowHandle, &mut AppContext) + 'static,
2725    ) -> Subscription {
2726        let window_handle = self.window.handle;
2727        let (subscription, activate) = self.app.release_listeners.insert(
2728            self.view.model.entity_id,
2729            Box::new(move |this, cx| {
2730                let this = this.downcast_mut().expect("invalid entity type");
2731                on_release(this, window_handle, cx)
2732            }),
2733        );
2734        activate();
2735        subscription
2736    }
2737
2738    /// Register a callback to be invoked when the given Model or View is released.
2739    pub fn observe_release<V2, E>(
2740        &mut self,
2741        entity: &E,
2742        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2743    ) -> Subscription
2744    where
2745        V: 'static,
2746        V2: 'static,
2747        E: Entity<V2>,
2748    {
2749        let view = self.view().downgrade();
2750        let entity_id = entity.entity_id();
2751        let window_handle = self.window.handle;
2752        let (subscription, activate) = self.app.release_listeners.insert(
2753            entity_id,
2754            Box::new(move |entity, cx| {
2755                let entity = entity.downcast_mut().expect("invalid entity type");
2756                let _ = window_handle.update(cx, |_, cx| {
2757                    view.update(cx, |this, cx| on_release(this, entity, cx))
2758                });
2759            }),
2760        );
2761        activate();
2762        subscription
2763    }
2764
2765    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
2766    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
2767    pub fn notify(&mut self) {
2768        for view_id in self
2769            .window
2770            .rendered_frame
2771            .dispatch_tree
2772            .view_path(self.view.entity_id())
2773            .into_iter()
2774            .rev()
2775        {
2776            if !self.window.dirty_views.insert(view_id) {
2777                break;
2778            }
2779        }
2780
2781        if !self.window.drawing {
2782            self.window_cx.window.dirty = true;
2783            self.window_cx.app.push_effect(Effect::Notify {
2784                emitter: self.view.model.entity_id,
2785            });
2786        }
2787    }
2788
2789    /// Register a callback to be invoked when the window is resized.
2790    pub fn observe_window_bounds(
2791        &mut self,
2792        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2793    ) -> Subscription {
2794        let view = self.view.downgrade();
2795        let (subscription, activate) = self.window.bounds_observers.insert(
2796            (),
2797            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2798        );
2799        activate();
2800        subscription
2801    }
2802
2803    /// Register a callback to be invoked when the window is activated or deactivated.
2804    pub fn observe_window_activation(
2805        &mut self,
2806        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2807    ) -> Subscription {
2808        let view = self.view.downgrade();
2809        let (subscription, activate) = self.window.activation_observers.insert(
2810            (),
2811            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2812        );
2813        activate();
2814        subscription
2815    }
2816
2817    /// Register a listener to be called when the given focus handle receives focus.
2818    /// Returns a subscription and persists until the subscription is dropped.
2819    pub fn on_focus(
2820        &mut self,
2821        handle: &FocusHandle,
2822        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2823    ) -> Subscription {
2824        let view = self.view.downgrade();
2825        let focus_id = handle.id;
2826        let (subscription, activate) = self.window.focus_listeners.insert(
2827            (),
2828            Box::new(move |event, cx| {
2829                view.update(cx, |view, cx| {
2830                    if event.previous_focus_path.last() != Some(&focus_id)
2831                        && event.current_focus_path.last() == Some(&focus_id)
2832                    {
2833                        listener(view, cx)
2834                    }
2835                })
2836                .is_ok()
2837            }),
2838        );
2839        self.app.defer(move |_| activate());
2840        subscription
2841    }
2842
2843    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2844    /// Returns a subscription and persists until the subscription is dropped.
2845    pub fn on_focus_in(
2846        &mut self,
2847        handle: &FocusHandle,
2848        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2849    ) -> Subscription {
2850        let view = self.view.downgrade();
2851        let focus_id = handle.id;
2852        let (subscription, activate) = self.window.focus_listeners.insert(
2853            (),
2854            Box::new(move |event, cx| {
2855                view.update(cx, |view, cx| {
2856                    if !event.previous_focus_path.contains(&focus_id)
2857                        && event.current_focus_path.contains(&focus_id)
2858                    {
2859                        listener(view, cx)
2860                    }
2861                })
2862                .is_ok()
2863            }),
2864        );
2865        self.app.defer(move |_| activate());
2866        subscription
2867    }
2868
2869    /// Register a listener to be called when the given focus handle loses focus.
2870    /// Returns a subscription and persists until the subscription is dropped.
2871    pub fn on_blur(
2872        &mut self,
2873        handle: &FocusHandle,
2874        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2875    ) -> Subscription {
2876        let view = self.view.downgrade();
2877        let focus_id = handle.id;
2878        let (subscription, activate) = self.window.focus_listeners.insert(
2879            (),
2880            Box::new(move |event, cx| {
2881                view.update(cx, |view, cx| {
2882                    if event.previous_focus_path.last() == Some(&focus_id)
2883                        && event.current_focus_path.last() != Some(&focus_id)
2884                    {
2885                        listener(view, cx)
2886                    }
2887                })
2888                .is_ok()
2889            }),
2890        );
2891        self.app.defer(move |_| activate());
2892        subscription
2893    }
2894
2895    /// Register a listener to be called when nothing in the window has focus.
2896    /// This typically happens when the node that was focused is removed from the tree,
2897    /// and this callback lets you chose a default place to restore the users focus.
2898    /// Returns a subscription and persists until the subscription is dropped.
2899    pub fn on_focus_lost(
2900        &mut self,
2901        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2902    ) -> Subscription {
2903        let view = self.view.downgrade();
2904        let (subscription, activate) = self.window.focus_lost_listeners.insert(
2905            (),
2906            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2907        );
2908        activate();
2909        subscription
2910    }
2911
2912    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2913    /// Returns a subscription and persists until the subscription is dropped.
2914    pub fn on_focus_out(
2915        &mut self,
2916        handle: &FocusHandle,
2917        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2918    ) -> Subscription {
2919        let view = self.view.downgrade();
2920        let focus_id = handle.id;
2921        let (subscription, activate) = self.window.focus_listeners.insert(
2922            (),
2923            Box::new(move |event, cx| {
2924                view.update(cx, |view, cx| {
2925                    if event.previous_focus_path.contains(&focus_id)
2926                        && !event.current_focus_path.contains(&focus_id)
2927                    {
2928                        listener(view, cx)
2929                    }
2930                })
2931                .is_ok()
2932            }),
2933        );
2934        self.app.defer(move |_| activate());
2935        subscription
2936    }
2937
2938    /// Schedule a future to be run asynchronously.
2939    /// The given callback is invoked with a [`WeakView<V>`] to avoid leaking the view for a long-running process.
2940    /// It's also given an [`AsyncWindowContext`], which can be used to access the state of the view across await points.
2941    /// The returned future will be polled on the main thread.
2942    pub fn spawn<Fut, R>(
2943        &mut self,
2944        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2945    ) -> Task<R>
2946    where
2947        R: 'static,
2948        Fut: Future<Output = R> + 'static,
2949    {
2950        let view = self.view().downgrade();
2951        self.window_cx.spawn(|cx| f(view, cx))
2952    }
2953
2954    /// Update the global state of the given type.
2955    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2956    where
2957        G: 'static,
2958    {
2959        let mut global = self.app.lease_global::<G>();
2960        let result = f(&mut global, self);
2961        self.app.end_global_lease(global);
2962        result
2963    }
2964
2965    /// Register a callback to be invoked when the given global state changes.
2966    pub fn observe_global<G: 'static>(
2967        &mut self,
2968        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2969    ) -> Subscription {
2970        let window_handle = self.window.handle;
2971        let view = self.view().downgrade();
2972        let (subscription, activate) = self.global_observers.insert(
2973            TypeId::of::<G>(),
2974            Box::new(move |cx| {
2975                window_handle
2976                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2977                    .unwrap_or(false)
2978            }),
2979        );
2980        self.app.defer(move |_| activate());
2981        subscription
2982    }
2983
2984    /// Add a listener for any mouse event that occurs in the window.
2985    /// This is a fairly low level method.
2986    /// Typically, you'll want to use methods on UI elements, which perform bounds checking etc.
2987    pub fn on_mouse_event<Event: MouseEvent>(
2988        &mut self,
2989        handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
2990    ) {
2991        let handle = self.view().clone();
2992        self.window_cx.on_mouse_event(move |event, phase, cx| {
2993            handle.update(cx, |view, cx| {
2994                handler(view, event, phase, cx);
2995            })
2996        });
2997    }
2998
2999    /// Register a callback to be invoked when the given Key Event is dispatched to the window.
3000    pub fn on_key_event<Event: KeyEvent>(
3001        &mut self,
3002        handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
3003    ) {
3004        let handle = self.view().clone();
3005        self.window_cx.on_key_event(move |event, phase, cx| {
3006            handle.update(cx, |view, cx| {
3007                handler(view, event, phase, cx);
3008            })
3009        });
3010    }
3011
3012    /// Register a callback to be invoked when the given Action type is dispatched to the window.
3013    pub fn on_action(
3014        &mut self,
3015        action_type: TypeId,
3016        listener: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
3017    ) {
3018        let handle = self.view().clone();
3019        self.window_cx
3020            .on_action(action_type, move |action, phase, cx| {
3021                handle.update(cx, |view, cx| {
3022                    listener(view, action, phase, cx);
3023                })
3024            });
3025    }
3026
3027    /// Emit an event to be handled any other views that have subscribed via [ViewContext::subscribe].
3028    pub fn emit<Evt>(&mut self, event: Evt)
3029    where
3030        Evt: 'static,
3031        V: EventEmitter<Evt>,
3032    {
3033        let emitter = self.view.model.entity_id;
3034        self.app.push_effect(Effect::Emit {
3035            emitter,
3036            event_type: TypeId::of::<Evt>(),
3037            event: Box::new(event),
3038        });
3039    }
3040
3041    /// Move focus to the current view, assuming it implements [`FocusableView`].
3042    pub fn focus_self(&mut self)
3043    where
3044        V: FocusableView,
3045    {
3046        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
3047    }
3048
3049    /// Convenience method for accessing view state in an event callback.
3050    ///
3051    /// Many GPUI callbacks take the form of `Fn(&E, &mut WindowContext)`,
3052    /// but it's often useful to be able to access view state in these
3053    /// callbacks. This method provides a convenient way to do so.
3054    pub fn listener<E>(
3055        &self,
3056        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
3057    ) -> impl Fn(&E, &mut WindowContext) + 'static {
3058        let view = self.view().downgrade();
3059        move |e: &E, cx: &mut WindowContext| {
3060            view.update(cx, |view, cx| f(view, e, cx)).ok();
3061        }
3062    }
3063}
3064
3065impl<V> Context for ViewContext<'_, V> {
3066    type Result<U> = U;
3067
3068    fn new_model<T: 'static>(
3069        &mut self,
3070        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
3071    ) -> Model<T> {
3072        self.window_cx.new_model(build_model)
3073    }
3074
3075    fn update_model<T: 'static, R>(
3076        &mut self,
3077        model: &Model<T>,
3078        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
3079    ) -> R {
3080        self.window_cx.update_model(model, update)
3081    }
3082
3083    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
3084    where
3085        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
3086    {
3087        self.window_cx.update_window(window, update)
3088    }
3089
3090    fn read_model<T, R>(
3091        &self,
3092        handle: &Model<T>,
3093        read: impl FnOnce(&T, &AppContext) -> R,
3094    ) -> Self::Result<R>
3095    where
3096        T: 'static,
3097    {
3098        self.window_cx.read_model(handle, read)
3099    }
3100
3101    fn read_window<T, R>(
3102        &self,
3103        window: &WindowHandle<T>,
3104        read: impl FnOnce(View<T>, &AppContext) -> R,
3105    ) -> Result<R>
3106    where
3107        T: 'static,
3108    {
3109        self.window_cx.read_window(window, read)
3110    }
3111}
3112
3113impl<V: 'static> VisualContext for ViewContext<'_, V> {
3114    fn new_view<W: Render + 'static>(
3115        &mut self,
3116        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
3117    ) -> Self::Result<View<W>> {
3118        self.window_cx.new_view(build_view_state)
3119    }
3120
3121    fn update_view<V2: 'static, R>(
3122        &mut self,
3123        view: &View<V2>,
3124        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
3125    ) -> Self::Result<R> {
3126        self.window_cx.update_view(view, update)
3127    }
3128
3129    fn replace_root_view<W>(
3130        &mut self,
3131        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
3132    ) -> Self::Result<View<W>>
3133    where
3134        W: 'static + Render,
3135    {
3136        self.window_cx.replace_root_view(build_view)
3137    }
3138
3139    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
3140        self.window_cx.focus_view(view)
3141    }
3142
3143    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
3144        self.window_cx.dismiss_view(view)
3145    }
3146}
3147
3148impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
3149    type Target = WindowContext<'a>;
3150
3151    fn deref(&self) -> &Self::Target {
3152        &self.window_cx
3153    }
3154}
3155
3156impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
3157    fn deref_mut(&mut self) -> &mut Self::Target {
3158        &mut self.window_cx
3159    }
3160}
3161
3162// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
3163slotmap::new_key_type! {
3164    /// A unique identifier for a window.
3165    pub struct WindowId;
3166}
3167
3168impl WindowId {
3169    /// Converts this window ID to a `u64`.
3170    pub fn as_u64(&self) -> u64 {
3171        self.0.as_ffi()
3172    }
3173}
3174
3175/// A handle to a window with a specific root view type.
3176/// Note that this does not keep the window alive on its own.
3177#[derive(Deref, DerefMut)]
3178pub struct WindowHandle<V> {
3179    #[deref]
3180    #[deref_mut]
3181    pub(crate) any_handle: AnyWindowHandle,
3182    state_type: PhantomData<V>,
3183}
3184
3185impl<V: 'static + Render> WindowHandle<V> {
3186    /// Create a new handle from a window ID.
3187    /// This does not check if the root type of the window is `V`.
3188    pub fn new(id: WindowId) -> Self {
3189        WindowHandle {
3190            any_handle: AnyWindowHandle {
3191                id,
3192                state_type: TypeId::of::<V>(),
3193            },
3194            state_type: PhantomData,
3195        }
3196    }
3197
3198    /// Get the root view out of this window.
3199    ///
3200    /// This will fail if the window is closed or if the root view's type does not match `V`.
3201    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
3202    where
3203        C: Context,
3204    {
3205        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
3206            root_view
3207                .downcast::<V>()
3208                .map_err(|_| anyhow!("the type of the window's root view has changed"))
3209        }))
3210    }
3211
3212    /// Update the root view of this window.
3213    ///
3214    /// This will fail if the window has been closed or if the root view's type does not match
3215    pub fn update<C, R>(
3216        &self,
3217        cx: &mut C,
3218        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
3219    ) -> Result<R>
3220    where
3221        C: Context,
3222    {
3223        cx.update_window(self.any_handle, |root_view, cx| {
3224            let view = root_view
3225                .downcast::<V>()
3226                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
3227            Ok(cx.update_view(&view, update))
3228        })?
3229    }
3230
3231    /// Read the root view out of this window.
3232    ///
3233    /// This will fail if the window is closed or if the root view's type does not match `V`.
3234    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
3235        let x = cx
3236            .windows
3237            .get(self.id)
3238            .and_then(|window| {
3239                window
3240                    .as_ref()
3241                    .and_then(|window| window.root_view.clone())
3242                    .map(|root_view| root_view.downcast::<V>())
3243            })
3244            .ok_or_else(|| anyhow!("window not found"))?
3245            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
3246
3247        Ok(x.read(cx))
3248    }
3249
3250    /// Read the root view out of this window, with a callback
3251    ///
3252    /// This will fail if the window is closed or if the root view's type does not match `V`.
3253    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
3254    where
3255        C: Context,
3256    {
3257        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
3258    }
3259
3260    /// Read the root view pointer off of this window.
3261    ///
3262    /// This will fail if the window is closed or if the root view's type does not match `V`.
3263    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
3264    where
3265        C: Context,
3266    {
3267        cx.read_window(self, |root_view, _cx| root_view.clone())
3268    }
3269
3270    /// Check if this window is 'active'.
3271    ///
3272    /// Will return `None` if the window is closed.
3273    pub fn is_active(&self, cx: &AppContext) -> Option<bool> {
3274        cx.windows
3275            .get(self.id)
3276            .and_then(|window| window.as_ref().map(|window| window.active))
3277    }
3278}
3279
3280impl<V> Copy for WindowHandle<V> {}
3281
3282impl<V> Clone for WindowHandle<V> {
3283    fn clone(&self) -> Self {
3284        *self
3285    }
3286}
3287
3288impl<V> PartialEq for WindowHandle<V> {
3289    fn eq(&self, other: &Self) -> bool {
3290        self.any_handle == other.any_handle
3291    }
3292}
3293
3294impl<V> Eq for WindowHandle<V> {}
3295
3296impl<V> Hash for WindowHandle<V> {
3297    fn hash<H: Hasher>(&self, state: &mut H) {
3298        self.any_handle.hash(state);
3299    }
3300}
3301
3302impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle {
3303    fn from(val: WindowHandle<V>) -> Self {
3304        val.any_handle
3305    }
3306}
3307
3308/// A handle to a window with any root view type, which can be downcast to a window with a specific root view type.
3309#[derive(Copy, Clone, PartialEq, Eq, Hash)]
3310pub struct AnyWindowHandle {
3311    pub(crate) id: WindowId,
3312    state_type: TypeId,
3313}
3314
3315impl AnyWindowHandle {
3316    /// Get the ID of this window.
3317    pub fn window_id(&self) -> WindowId {
3318        self.id
3319    }
3320
3321    /// Attempt to convert this handle to a window handle with a specific root view type.
3322    /// If the types do not match, this will return `None`.
3323    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
3324        if TypeId::of::<T>() == self.state_type {
3325            Some(WindowHandle {
3326                any_handle: *self,
3327                state_type: PhantomData,
3328            })
3329        } else {
3330            None
3331        }
3332    }
3333
3334    /// Update the state of the root view of this window.
3335    ///
3336    /// This will fail if the window has been closed.
3337    pub fn update<C, R>(
3338        self,
3339        cx: &mut C,
3340        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
3341    ) -> Result<R>
3342    where
3343        C: Context,
3344    {
3345        cx.update_window(self, update)
3346    }
3347
3348    /// Read the state of the root view of this window.
3349    ///
3350    /// This will fail if the window has been closed.
3351    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
3352    where
3353        C: Context,
3354        T: 'static,
3355    {
3356        let view = self
3357            .downcast::<T>()
3358            .context("the type of the window's root view has changed")?;
3359
3360        cx.read_window(&view, read)
3361    }
3362}
3363
3364/// An identifier for an [`Element`](crate::Element).
3365///
3366/// Can be constructed with a string, a number, or both, as well
3367/// as other internal representations.
3368#[derive(Clone, Debug, Eq, PartialEq, Hash)]
3369pub enum ElementId {
3370    /// The ID of a View element
3371    View(EntityId),
3372    /// An integer ID.
3373    Integer(usize),
3374    /// A string based ID.
3375    Name(SharedString),
3376    /// An ID that's equated with a focus handle.
3377    FocusHandle(FocusId),
3378    /// A combination of a name and an integer.
3379    NamedInteger(SharedString, usize),
3380}
3381
3382impl ElementId {
3383    pub(crate) fn from_entity_id(entity_id: EntityId) -> Self {
3384        ElementId::View(entity_id)
3385    }
3386}
3387
3388impl TryInto<SharedString> for ElementId {
3389    type Error = anyhow::Error;
3390
3391    fn try_into(self) -> anyhow::Result<SharedString> {
3392        if let ElementId::Name(name) = self {
3393            Ok(name)
3394        } else {
3395            Err(anyhow!("element id is not string"))
3396        }
3397    }
3398}
3399
3400impl From<usize> for ElementId {
3401    fn from(id: usize) -> Self {
3402        ElementId::Integer(id)
3403    }
3404}
3405
3406impl From<i32> for ElementId {
3407    fn from(id: i32) -> Self {
3408        Self::Integer(id as usize)
3409    }
3410}
3411
3412impl From<SharedString> for ElementId {
3413    fn from(name: SharedString) -> Self {
3414        ElementId::Name(name)
3415    }
3416}
3417
3418impl From<&'static str> for ElementId {
3419    fn from(name: &'static str) -> Self {
3420        ElementId::Name(name.into())
3421    }
3422}
3423
3424impl<'a> From<&'a FocusHandle> for ElementId {
3425    fn from(handle: &'a FocusHandle) -> Self {
3426        ElementId::FocusHandle(handle.id)
3427    }
3428}
3429
3430impl From<(&'static str, EntityId)> for ElementId {
3431    fn from((name, id): (&'static str, EntityId)) -> Self {
3432        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
3433    }
3434}
3435
3436impl From<(&'static str, usize)> for ElementId {
3437    fn from((name, id): (&'static str, usize)) -> Self {
3438        ElementId::NamedInteger(name.into(), id)
3439    }
3440}
3441
3442impl From<(&'static str, u64)> for ElementId {
3443    fn from((name, id): (&'static str, u64)) -> Self {
3444        ElementId::NamedInteger(name.into(), id as usize)
3445    }
3446}
3447
3448/// A rectangle to be rendered in the window at the given position and size.
3449/// Passed as an argument [`WindowContext::paint_quad`].
3450#[derive(Clone)]
3451pub struct PaintQuad {
3452    bounds: Bounds<Pixels>,
3453    corner_radii: Corners<Pixels>,
3454    background: Hsla,
3455    border_widths: Edges<Pixels>,
3456    border_color: Hsla,
3457}
3458
3459impl PaintQuad {
3460    /// Set the corner radii of the quad.
3461    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
3462        PaintQuad {
3463            corner_radii: corner_radii.into(),
3464            ..self
3465        }
3466    }
3467
3468    /// Set the border widths of the quad.
3469    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
3470        PaintQuad {
3471            border_widths: border_widths.into(),
3472            ..self
3473        }
3474    }
3475
3476    /// Set the border color of the quad.
3477    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
3478        PaintQuad {
3479            border_color: border_color.into(),
3480            ..self
3481        }
3482    }
3483
3484    /// Set the background color of the quad.
3485    pub fn background(self, background: impl Into<Hsla>) -> Self {
3486        PaintQuad {
3487            background: background.into(),
3488            ..self
3489        }
3490    }
3491}
3492
3493/// Create a quad with the given parameters.
3494pub fn quad(
3495    bounds: Bounds<Pixels>,
3496    corner_radii: impl Into<Corners<Pixels>>,
3497    background: impl Into<Hsla>,
3498    border_widths: impl Into<Edges<Pixels>>,
3499    border_color: impl Into<Hsla>,
3500) -> PaintQuad {
3501    PaintQuad {
3502        bounds,
3503        corner_radii: corner_radii.into(),
3504        background: background.into(),
3505        border_widths: border_widths.into(),
3506        border_color: border_color.into(),
3507    }
3508}
3509
3510/// Create a filled quad with the given bounds and background color.
3511pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
3512    PaintQuad {
3513        bounds: bounds.into(),
3514        corner_radii: (0.).into(),
3515        background: background.into(),
3516        border_widths: (0.).into(),
3517        border_color: transparent_black(),
3518    }
3519}
3520
3521/// Create a rectangle outline with the given bounds, border color, and a 1px border width
3522pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
3523    PaintQuad {
3524        bounds: bounds.into(),
3525        corner_radii: (0.).into(),
3526        background: transparent_black(),
3527        border_widths: (1.).into(),
3528        border_color: border_color.into(),
3529    }
3530}