window.rs

   1use crate::{
   2    key_dispatch::DispatchActionListener, px, size, transparent_black, Action, AnyDrag, AnyView,
   3    AppContext, AsyncWindowContext, AvailableSpace, Bounds, BoxShadow, Context, Corners,
   4    CursorStyle, DevicePixels, DispatchNodeId, DispatchTree, DisplayId, Edges, Effect, Entity,
   5    EntityId, EventEmitter, FileDropEvent, Flatten, FontId, GlobalElementId, GlyphId, Hsla,
   6    ImageData, InputEvent, IsZero, KeyBinding, KeyContext, KeyDownEvent, KeystrokeEvent, LayoutId,
   7    Model, ModelContext, Modifiers, MonochromeSprite, MouseButton, MouseMoveEvent, MouseUpEvent,
   8    Path, Pixels, PlatformAtlas, PlatformDisplay, PlatformInputHandler, PlatformWindow, Point,
   9    PolychromeSprite, PromptLevel, Quad, Render, RenderGlyphParams, RenderImageParams,
  10    RenderSvgParams, ScaledPixels, Scene, SceneBuilder, Shadow, SharedString, Size, Style,
  11    SubscriberSet, Subscription, Surface, TaffyLayoutEngine, Task, Underline, UnderlineStyle, View,
  12    VisualContext, WeakView, WindowBounds, WindowOptions, SUBPIXEL_VARIANTS,
  13};
  14use anyhow::{anyhow, Context as _, Result};
  15use collections::FxHashMap;
  16use derive_more::{Deref, DerefMut};
  17use futures::{
  18    channel::{mpsc, oneshot},
  19    StreamExt,
  20};
  21use media::core_video::CVImageBuffer;
  22use parking_lot::RwLock;
  23use slotmap::SlotMap;
  24use smallvec::SmallVec;
  25use std::{
  26    any::{Any, TypeId},
  27    borrow::{Borrow, BorrowMut, Cow},
  28    fmt::Debug,
  29    future::Future,
  30    hash::{Hash, Hasher},
  31    marker::PhantomData,
  32    mem,
  33    rc::Rc,
  34    sync::{
  35        atomic::{AtomicUsize, Ordering::SeqCst},
  36        Arc,
  37    },
  38};
  39use util::ResultExt;
  40
  41const ACTIVE_DRAG_Z_INDEX: u8 = 1;
  42
  43/// A global stacking order, which is created by stacking successive z-index values.
  44/// Each z-index will always be interpreted in the context of its parent z-index.
  45#[derive(Deref, DerefMut, Clone, Debug, Ord, PartialOrd, PartialEq, Eq)]
  46pub struct StackingOrder {
  47    #[deref]
  48    #[deref_mut]
  49    z_indices: SmallVec<[u8; 64]>,
  50}
  51
  52impl Default for StackingOrder {
  53    fn default() -> Self {
  54        StackingOrder {
  55            z_indices: SmallVec::new(),
  56        }
  57    }
  58}
  59
  60/// Represents the two different phases when dispatching events.
  61#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  62pub enum DispatchPhase {
  63    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  64    /// invoked front to back and keyboard event listeners are invoked from the focused element
  65    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  66    /// registering event listeners.
  67    #[default]
  68    Bubble,
  69    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  70    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  71    /// is used for special purposes such as clearing the "pressed" state for click events. If
  72    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  73    /// outside of the immediate region may rely on detecting non-local events during this phase.
  74    Capture,
  75}
  76
  77impl DispatchPhase {
  78    pub fn bubble(self) -> bool {
  79        self == DispatchPhase::Bubble
  80    }
  81
  82    pub fn capture(self) -> bool {
  83        self == DispatchPhase::Capture
  84    }
  85}
  86
  87type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
  88type AnyMouseListener = Box<dyn FnMut(&dyn Any, DispatchPhase, &mut WindowContext) + 'static>;
  89type AnyWindowFocusListener = Box<dyn FnMut(&FocusEvent, &mut WindowContext) -> bool + 'static>;
  90
  91struct FocusEvent {
  92    previous_focus_path: SmallVec<[FocusId; 8]>,
  93    current_focus_path: SmallVec<[FocusId; 8]>,
  94}
  95
  96slotmap::new_key_type! { pub struct FocusId; }
  97
  98impl FocusId {
  99    /// Obtains whether the element associated with this handle is currently focused.
 100    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 101        cx.window.focus == Some(*self)
 102    }
 103
 104    /// Obtains whether the element associated with this handle contains the focused
 105    /// element or is itself focused.
 106    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 107        cx.focused()
 108            .map_or(false, |focused| self.contains(focused.id, cx))
 109    }
 110
 111    /// Obtains whether the element associated with this handle is contained within the
 112    /// focused element or is itself focused.
 113    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 114        let focused = cx.focused();
 115        focused.map_or(false, |focused| focused.id.contains(*self, cx))
 116    }
 117
 118    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 119    pub(crate) fn contains(&self, other: Self, cx: &WindowContext) -> bool {
 120        cx.window
 121            .rendered_frame
 122            .dispatch_tree
 123            .focus_contains(*self, other)
 124    }
 125}
 126
 127/// A handle which can be used to track and manipulate the focused element in a window.
 128pub struct FocusHandle {
 129    pub(crate) id: FocusId,
 130    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 131}
 132
 133impl std::fmt::Debug for FocusHandle {
 134    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 135        f.write_fmt(format_args!("FocusHandle({:?})", self.id))
 136    }
 137}
 138
 139impl FocusHandle {
 140    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
 141        let id = handles.write().insert(AtomicUsize::new(1));
 142        Self {
 143            id,
 144            handles: handles.clone(),
 145        }
 146    }
 147
 148    pub(crate) fn for_id(
 149        id: FocusId,
 150        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 151    ) -> Option<Self> {
 152        let lock = handles.read();
 153        let ref_count = lock.get(id)?;
 154        if ref_count.load(SeqCst) == 0 {
 155            None
 156        } else {
 157            ref_count.fetch_add(1, SeqCst);
 158            Some(Self {
 159                id,
 160                handles: handles.clone(),
 161            })
 162        }
 163    }
 164
 165    /// Moves the focus to the element associated with this handle.
 166    pub fn focus(&self, cx: &mut WindowContext) {
 167        cx.focus(self)
 168    }
 169
 170    /// Obtains whether the element associated with this handle is currently focused.
 171    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 172        self.id.is_focused(cx)
 173    }
 174
 175    /// Obtains whether the element associated with this handle contains the focused
 176    /// element or is itself focused.
 177    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 178        self.id.contains_focused(cx)
 179    }
 180
 181    /// Obtains whether the element associated with this handle is contained within the
 182    /// focused element or is itself focused.
 183    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 184        self.id.within_focused(cx)
 185    }
 186
 187    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 188    pub fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 189        self.id.contains(other.id, cx)
 190    }
 191}
 192
 193impl Clone for FocusHandle {
 194    fn clone(&self) -> Self {
 195        Self::for_id(self.id, &self.handles).unwrap()
 196    }
 197}
 198
 199impl PartialEq for FocusHandle {
 200    fn eq(&self, other: &Self) -> bool {
 201        self.id == other.id
 202    }
 203}
 204
 205impl Eq for FocusHandle {}
 206
 207impl Drop for FocusHandle {
 208    fn drop(&mut self) {
 209        self.handles
 210            .read()
 211            .get(self.id)
 212            .unwrap()
 213            .fetch_sub(1, SeqCst);
 214    }
 215}
 216
 217/// FocusableView allows users of your view to easily
 218/// focus it (using cx.focus_view(view))
 219pub trait FocusableView: 'static + Render {
 220    fn focus_handle(&self, cx: &AppContext) -> FocusHandle;
 221}
 222
 223/// ManagedView is a view (like a Modal, Popover, Menu, etc.)
 224/// where the lifecycle of the view is handled by another view.
 225pub trait ManagedView: FocusableView + EventEmitter<DismissEvent> {}
 226
 227impl<M: FocusableView + EventEmitter<DismissEvent>> ManagedView for M {}
 228
 229pub struct DismissEvent;
 230
 231// Holds the state for a specific window.
 232pub struct Window {
 233    pub(crate) handle: AnyWindowHandle,
 234    pub(crate) removed: bool,
 235    pub(crate) platform_window: Box<dyn PlatformWindow>,
 236    display_id: DisplayId,
 237    sprite_atlas: Arc<dyn PlatformAtlas>,
 238    rem_size: Pixels,
 239    viewport_size: Size<Pixels>,
 240    layout_engine: Option<TaffyLayoutEngine>,
 241    pub(crate) root_view: Option<AnyView>,
 242    pub(crate) element_id_stack: GlobalElementId,
 243    pub(crate) rendered_frame: Frame,
 244    pub(crate) next_frame: Frame,
 245    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 246    focus_listeners: SubscriberSet<(), AnyWindowFocusListener>,
 247    blur_listeners: SubscriberSet<(), AnyObserver>,
 248    default_prevented: bool,
 249    mouse_position: Point<Pixels>,
 250    modifiers: Modifiers,
 251    requested_cursor_style: Option<CursorStyle>,
 252    scale_factor: f32,
 253    bounds: WindowBounds,
 254    bounds_observers: SubscriberSet<(), AnyObserver>,
 255    active: bool,
 256    pub(crate) dirty: bool,
 257    pub(crate) drawing: bool,
 258    activation_observers: SubscriberSet<(), AnyObserver>,
 259    pub(crate) focus: Option<FocusId>,
 260
 261    #[cfg(any(test, feature = "test-support"))]
 262    pub(crate) focus_invalidated: bool,
 263}
 264
 265pub(crate) struct ElementStateBox {
 266    inner: Box<dyn Any>,
 267    #[cfg(debug_assertions)]
 268    type_name: &'static str,
 269}
 270
 271// #[derive(Default)]
 272pub(crate) struct Frame {
 273    focus: Option<FocusId>,
 274    pub(crate) element_states: FxHashMap<GlobalElementId, ElementStateBox>,
 275    mouse_listeners: FxHashMap<TypeId, Vec<(StackingOrder, AnyMouseListener)>>,
 276    pub(crate) dispatch_tree: DispatchTree,
 277    pub(crate) scene_builder: SceneBuilder,
 278    pub(crate) depth_map: Vec<(StackingOrder, Bounds<Pixels>)>,
 279    pub(crate) z_index_stack: StackingOrder,
 280    content_mask_stack: Vec<ContentMask<Pixels>>,
 281    element_offset_stack: Vec<Point<Pixels>>,
 282}
 283
 284impl Frame {
 285    fn new(dispatch_tree: DispatchTree) -> Self {
 286        Frame {
 287            focus: None,
 288            element_states: FxHashMap::default(),
 289            mouse_listeners: FxHashMap::default(),
 290            dispatch_tree,
 291            scene_builder: SceneBuilder::default(),
 292            z_index_stack: StackingOrder::default(),
 293            depth_map: Default::default(),
 294            content_mask_stack: Vec::new(),
 295            element_offset_stack: Vec::new(),
 296        }
 297    }
 298
 299    fn clear(&mut self) {
 300        self.element_states.clear();
 301        self.mouse_listeners.values_mut().for_each(Vec::clear);
 302        self.dispatch_tree.clear();
 303        self.depth_map.clear();
 304    }
 305
 306    fn focus_path(&self) -> SmallVec<[FocusId; 8]> {
 307        self.focus
 308            .map(|focus_id| self.dispatch_tree.focus_path(focus_id))
 309            .unwrap_or_default()
 310    }
 311}
 312
 313impl Window {
 314    pub(crate) fn new(
 315        handle: AnyWindowHandle,
 316        options: WindowOptions,
 317        cx: &mut AppContext,
 318    ) -> Self {
 319        let platform_window = cx.platform.open_window(
 320            handle,
 321            options,
 322            Box::new({
 323                let mut cx = cx.to_async();
 324                move || handle.update(&mut cx, |_, cx| cx.draw())
 325            }),
 326        );
 327        let display_id = platform_window.display().id();
 328        let sprite_atlas = platform_window.sprite_atlas();
 329        let mouse_position = platform_window.mouse_position();
 330        let modifiers = platform_window.modifiers();
 331        let content_size = platform_window.content_size();
 332        let scale_factor = platform_window.scale_factor();
 333        let bounds = platform_window.bounds();
 334
 335        platform_window.on_resize(Box::new({
 336            let mut cx = cx.to_async();
 337            move |_, _| {
 338                handle
 339                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 340                    .log_err();
 341            }
 342        }));
 343        platform_window.on_moved(Box::new({
 344            let mut cx = cx.to_async();
 345            move || {
 346                handle
 347                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 348                    .log_err();
 349            }
 350        }));
 351        platform_window.on_active_status_change(Box::new({
 352            let mut cx = cx.to_async();
 353            move |active| {
 354                handle
 355                    .update(&mut cx, |_, cx| {
 356                        cx.window.active = active;
 357                        cx.window
 358                            .activation_observers
 359                            .clone()
 360                            .retain(&(), |callback| callback(cx));
 361                    })
 362                    .log_err();
 363            }
 364        }));
 365
 366        platform_window.on_input({
 367            let mut cx = cx.to_async();
 368            Box::new(move |event| {
 369                handle
 370                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 371                    .log_err()
 372                    .unwrap_or(false)
 373            })
 374        });
 375
 376        Window {
 377            handle,
 378            removed: false,
 379            platform_window,
 380            display_id,
 381            sprite_atlas,
 382            rem_size: px(16.),
 383            viewport_size: content_size,
 384            layout_engine: Some(TaffyLayoutEngine::new()),
 385            root_view: None,
 386            element_id_stack: GlobalElementId::default(),
 387            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 388            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 389            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 390            focus_listeners: SubscriberSet::new(),
 391            blur_listeners: SubscriberSet::new(),
 392            default_prevented: true,
 393            mouse_position,
 394            modifiers,
 395            requested_cursor_style: None,
 396            scale_factor,
 397            bounds,
 398            bounds_observers: SubscriberSet::new(),
 399            active: false,
 400            dirty: false,
 401            drawing: false,
 402            activation_observers: SubscriberSet::new(),
 403            focus: None,
 404
 405            #[cfg(any(test, feature = "test-support"))]
 406            focus_invalidated: false,
 407        }
 408    }
 409}
 410
 411/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 412/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 413/// to leave room to support more complex shapes in the future.
 414#[derive(Clone, Debug, Default, PartialEq, Eq)]
 415#[repr(C)]
 416pub struct ContentMask<P: Clone + Default + Debug> {
 417    pub bounds: Bounds<P>,
 418}
 419
 420impl ContentMask<Pixels> {
 421    /// Scale the content mask's pixel units by the given scaling factor.
 422    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 423        ContentMask {
 424            bounds: self.bounds.scale(factor),
 425        }
 426    }
 427
 428    /// Intersect the content mask with the given content mask.
 429    pub fn intersect(&self, other: &Self) -> Self {
 430        let bounds = self.bounds.intersect(&other.bounds);
 431        ContentMask { bounds }
 432    }
 433}
 434
 435/// Provides access to application state in the context of a single window. Derefs
 436/// to an `AppContext`, so you can also pass a `WindowContext` to any method that takes
 437/// an `AppContext` and call any `AppContext` methods.
 438pub struct WindowContext<'a> {
 439    pub(crate) app: &'a mut AppContext,
 440    pub(crate) window: &'a mut Window,
 441}
 442
 443impl<'a> WindowContext<'a> {
 444    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 445        Self { app, window }
 446    }
 447
 448    /// Obtain a handle to the window that belongs to this context.
 449    pub fn window_handle(&self) -> AnyWindowHandle {
 450        self.window.handle
 451    }
 452
 453    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 454    pub fn notify(&mut self) {
 455        if !self.window.drawing {
 456            self.window.dirty = true;
 457        }
 458    }
 459
 460    /// Close this window.
 461    pub fn remove_window(&mut self) {
 462        self.window.removed = true;
 463    }
 464
 465    /// Obtain a new `FocusHandle`, which allows you to track and manipulate the keyboard focus
 466    /// for elements rendered within this window.
 467    pub fn focus_handle(&mut self) -> FocusHandle {
 468        FocusHandle::new(&self.window.focus_handles)
 469    }
 470
 471    /// Obtain the currently focused `FocusHandle`. If no elements are focused, returns `None`.
 472    pub fn focused(&self) -> Option<FocusHandle> {
 473        self.window
 474            .focus
 475            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 476    }
 477
 478    /// Move focus to the element associated with the given `FocusHandle`.
 479    pub fn focus(&mut self, handle: &FocusHandle) {
 480        if self.window.focus == Some(handle.id) {
 481            return;
 482        }
 483
 484        self.window.focus = Some(handle.id);
 485        self.window
 486            .rendered_frame
 487            .dispatch_tree
 488            .clear_pending_keystrokes();
 489
 490        #[cfg(any(test, feature = "test-support"))]
 491        {
 492            println!("invalidating focus");
 493            self.window.focus_invalidated = true;
 494        }
 495
 496        self.notify();
 497    }
 498
 499    /// Remove focus from all elements within this context's window.
 500    pub fn blur(&mut self) {
 501        self.window.focus = None;
 502        self.notify();
 503    }
 504
 505    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 506        let focus_handle = self.focused();
 507
 508        self.defer(move |cx| {
 509            let node_id = focus_handle
 510                .and_then(|handle| {
 511                    cx.window
 512                        .rendered_frame
 513                        .dispatch_tree
 514                        .focusable_node_id(handle.id)
 515                })
 516                .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 517
 518            cx.propagate_event = true;
 519            cx.dispatch_action_on_node(node_id, action);
 520        })
 521    }
 522
 523    pub(crate) fn dispatch_keystroke_observers(
 524        &mut self,
 525        event: &dyn Any,
 526        action: Option<Box<dyn Action>>,
 527    ) {
 528        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 529            return;
 530        };
 531
 532        self.keystroke_observers
 533            .clone()
 534            .retain(&(), move |callback| {
 535                (callback)(
 536                    &KeystrokeEvent {
 537                        keystroke: key_down_event.keystroke.clone(),
 538                        action: action.as_ref().map(|action| action.boxed_clone()),
 539                    },
 540                    self,
 541                );
 542                true
 543            });
 544    }
 545
 546    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 547    /// that are currently on the stack to be returned to the app.
 548    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 549        let handle = self.window.handle;
 550        self.app.defer(move |cx| {
 551            handle.update(cx, |_, cx| f(cx)).ok();
 552        });
 553    }
 554
 555    pub fn subscribe<Emitter, E, Evt>(
 556        &mut self,
 557        entity: &E,
 558        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 559    ) -> Subscription
 560    where
 561        Emitter: EventEmitter<Evt>,
 562        E: Entity<Emitter>,
 563        Evt: 'static,
 564    {
 565        let entity_id = entity.entity_id();
 566        let entity = entity.downgrade();
 567        let window_handle = self.window.handle;
 568        let (subscription, activate) = self.app.event_listeners.insert(
 569            entity_id,
 570            (
 571                TypeId::of::<Evt>(),
 572                Box::new(move |event, cx| {
 573                    window_handle
 574                        .update(cx, |_, cx| {
 575                            if let Some(handle) = E::upgrade_from(&entity) {
 576                                let event = event.downcast_ref().expect("invalid event type");
 577                                on_event(handle, event, cx);
 578                                true
 579                            } else {
 580                                false
 581                            }
 582                        })
 583                        .unwrap_or(false)
 584                }),
 585            ),
 586        );
 587        self.app.defer(move |_| activate());
 588        subscription
 589    }
 590
 591    /// Create an `AsyncWindowContext`, which has a static lifetime and can be held across
 592    /// await points in async code.
 593    pub fn to_async(&self) -> AsyncWindowContext {
 594        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 595    }
 596
 597    /// Schedule the given closure to be run directly after the current frame is rendered.
 598    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 599        let handle = self.window.handle;
 600        let display_id = self.window.display_id;
 601
 602        if !self.frame_consumers.contains_key(&display_id) {
 603            let (tx, mut rx) = mpsc::unbounded::<()>();
 604            self.platform.set_display_link_output_callback(
 605                display_id,
 606                Box::new(move |_current_time, _output_time| _ = tx.unbounded_send(())),
 607            );
 608
 609            let consumer_task = self.app.spawn(|cx| async move {
 610                while rx.next().await.is_some() {
 611                    cx.update(|cx| {
 612                        for callback in cx
 613                            .next_frame_callbacks
 614                            .get_mut(&display_id)
 615                            .unwrap()
 616                            .drain(..)
 617                            .collect::<SmallVec<[_; 32]>>()
 618                        {
 619                            callback(cx);
 620                        }
 621                    })
 622                    .ok();
 623
 624                    // Flush effects, then stop the display link if no new next_frame_callbacks have been added.
 625
 626                    cx.update(|cx| {
 627                        if cx.next_frame_callbacks.is_empty() {
 628                            cx.platform.stop_display_link(display_id);
 629                        }
 630                    })
 631                    .ok();
 632                }
 633            });
 634            self.frame_consumers.insert(display_id, consumer_task);
 635        }
 636
 637        if self.next_frame_callbacks.is_empty() {
 638            self.platform.start_display_link(display_id);
 639        }
 640
 641        self.next_frame_callbacks
 642            .entry(display_id)
 643            .or_default()
 644            .push(Box::new(move |cx: &mut AppContext| {
 645                cx.update_window(handle, |_root_view, cx| callback(cx)).ok();
 646            }));
 647    }
 648
 649    /// Spawn the future returned by the given closure on the application thread pool.
 650    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 651    /// use within your future.
 652    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 653    where
 654        R: 'static,
 655        Fut: Future<Output = R> + 'static,
 656    {
 657        self.app
 658            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 659    }
 660
 661    /// Update the global of the given type. The given closure is given simultaneous mutable
 662    /// access both to the global and the context.
 663    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 664    where
 665        G: 'static,
 666    {
 667        let mut global = self.app.lease_global::<G>();
 668        let result = f(&mut global, self);
 669        self.app.end_global_lease(global);
 670        result
 671    }
 672
 673    #[must_use]
 674    /// Add a node to the layout tree for the current frame. Takes the `Style` of the element for which
 675    /// layout is being requested, along with the layout ids of any children. This method is called during
 676    /// calls to the `Element::layout` trait method and enables any element to participate in layout.
 677    pub fn request_layout(
 678        &mut self,
 679        style: &Style,
 680        children: impl IntoIterator<Item = LayoutId>,
 681    ) -> LayoutId {
 682        self.app.layout_id_buffer.clear();
 683        self.app.layout_id_buffer.extend(children.into_iter());
 684        let rem_size = self.rem_size();
 685
 686        self.window.layout_engine.as_mut().unwrap().request_layout(
 687            style,
 688            rem_size,
 689            &self.app.layout_id_buffer,
 690        )
 691    }
 692
 693    /// Add a node to the layout tree for the current frame. Instead of taking a `Style` and children,
 694    /// this variant takes a function that is invoked during layout so you can use arbitrary logic to
 695    /// determine the element's size. One place this is used internally is when measuring text.
 696    ///
 697    /// The given closure is invoked at layout time with the known dimensions and available space and
 698    /// returns a `Size`.
 699    pub fn request_measured_layout<
 700        F: FnMut(Size<Option<Pixels>>, Size<AvailableSpace>, &mut WindowContext) -> Size<Pixels>
 701            + 'static,
 702    >(
 703        &mut self,
 704        style: Style,
 705        measure: F,
 706    ) -> LayoutId {
 707        let rem_size = self.rem_size();
 708        self.window
 709            .layout_engine
 710            .as_mut()
 711            .unwrap()
 712            .request_measured_layout(style, rem_size, measure)
 713    }
 714
 715    pub fn compute_layout(&mut self, layout_id: LayoutId, available_space: Size<AvailableSpace>) {
 716        let mut layout_engine = self.window.layout_engine.take().unwrap();
 717        layout_engine.compute_layout(layout_id, available_space, self);
 718        self.window.layout_engine = Some(layout_engine);
 719    }
 720
 721    /// Obtain the bounds computed for the given LayoutId relative to the window. This method should not
 722    /// be invoked until the paint phase begins, and will usually be invoked by GPUI itself automatically
 723    /// in order to pass your element its `Bounds` automatically.
 724    pub fn layout_bounds(&mut self, layout_id: LayoutId) -> Bounds<Pixels> {
 725        let mut bounds = self
 726            .window
 727            .layout_engine
 728            .as_mut()
 729            .unwrap()
 730            .layout_bounds(layout_id)
 731            .map(Into::into);
 732        bounds.origin += self.element_offset();
 733        bounds
 734    }
 735
 736    fn window_bounds_changed(&mut self) {
 737        self.window.scale_factor = self.window.platform_window.scale_factor();
 738        self.window.viewport_size = self.window.platform_window.content_size();
 739        self.window.bounds = self.window.platform_window.bounds();
 740        self.window.display_id = self.window.platform_window.display().id();
 741        self.notify();
 742
 743        self.window
 744            .bounds_observers
 745            .clone()
 746            .retain(&(), |callback| callback(self));
 747    }
 748
 749    pub fn window_bounds(&self) -> WindowBounds {
 750        self.window.bounds
 751    }
 752
 753    pub fn viewport_size(&self) -> Size<Pixels> {
 754        self.window.viewport_size
 755    }
 756
 757    pub fn is_window_active(&self) -> bool {
 758        self.window.active
 759    }
 760
 761    pub fn zoom_window(&self) {
 762        self.window.platform_window.zoom();
 763    }
 764
 765    pub fn set_window_title(&mut self, title: &str) {
 766        self.window.platform_window.set_title(title);
 767    }
 768
 769    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 770        self.platform
 771            .displays()
 772            .into_iter()
 773            .find(|display| display.id() == self.window.display_id)
 774    }
 775
 776    pub fn show_character_palette(&self) {
 777        self.window.platform_window.show_character_palette();
 778    }
 779
 780    /// The scale factor of the display associated with the window. For example, it could
 781    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 782    /// be rendered as two pixels on screen.
 783    pub fn scale_factor(&self) -> f32 {
 784        self.window.scale_factor
 785    }
 786
 787    /// The size of an em for the base font of the application. Adjusting this value allows the
 788    /// UI to scale, just like zooming a web page.
 789    pub fn rem_size(&self) -> Pixels {
 790        self.window.rem_size
 791    }
 792
 793    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 794    /// UI to scale, just like zooming a web page.
 795    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 796        self.window.rem_size = rem_size.into();
 797    }
 798
 799    /// The line height associated with the current text style.
 800    pub fn line_height(&self) -> Pixels {
 801        let rem_size = self.rem_size();
 802        let text_style = self.text_style();
 803        text_style
 804            .line_height
 805            .to_pixels(text_style.font_size.into(), rem_size)
 806    }
 807
 808    /// Call to prevent the default action of an event. Currently only used to prevent
 809    /// parent elements from becoming focused on mouse down.
 810    pub fn prevent_default(&mut self) {
 811        self.window.default_prevented = true;
 812    }
 813
 814    /// Obtain whether default has been prevented for the event currently being dispatched.
 815    pub fn default_prevented(&self) -> bool {
 816        self.window.default_prevented
 817    }
 818
 819    /// Register a mouse event listener on the window for the next frame. The type of event
 820    /// is determined by the first parameter of the given listener. When the next frame is rendered
 821    /// the listener will be cleared.
 822    ///
 823    /// This is a fairly low-level method, so prefer using event handlers on elements unless you have
 824    /// a specific need to register a global listener.
 825    pub fn on_mouse_event<Event: 'static>(
 826        &mut self,
 827        mut handler: impl FnMut(&Event, DispatchPhase, &mut WindowContext) + 'static,
 828    ) {
 829        let order = self.window.next_frame.z_index_stack.clone();
 830        self.window
 831            .next_frame
 832            .mouse_listeners
 833            .entry(TypeId::of::<Event>())
 834            .or_default()
 835            .push((
 836                order,
 837                Box::new(move |event: &dyn Any, phase, cx| {
 838                    handler(event.downcast_ref().unwrap(), phase, cx)
 839                }),
 840            ))
 841    }
 842
 843    /// Register a key event listener on the window for the next frame. The type of event
 844    /// is determined by the first parameter of the given listener. When the next frame is rendered
 845    /// the listener will be cleared.
 846    ///
 847    /// This is a fairly low-level method, so prefer using event handlers on elements unless you have
 848    /// a specific need to register a global listener.
 849    pub fn on_key_event<Event: 'static>(
 850        &mut self,
 851        handler: impl Fn(&Event, DispatchPhase, &mut WindowContext) + 'static,
 852    ) {
 853        self.window
 854            .next_frame
 855            .dispatch_tree
 856            .on_key_event(Rc::new(move |event, phase, cx| {
 857                if let Some(event) = event.downcast_ref::<Event>() {
 858                    handler(event, phase, cx)
 859                }
 860            }));
 861    }
 862
 863    /// Register an action listener on the window for the next frame. The type of action
 864    /// is determined by the first parameter of the given listener. When the next frame is rendered
 865    /// the listener will be cleared.
 866    ///
 867    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
 868    /// a specific need to register a global listener.
 869    pub fn on_action(
 870        &mut self,
 871        action_type: TypeId,
 872        handler: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
 873    ) {
 874        self.window.next_frame.dispatch_tree.on_action(
 875            action_type,
 876            Rc::new(move |action, phase, cx| handler(action, phase, cx)),
 877        );
 878    }
 879
 880    pub fn is_action_available(&self, action: &dyn Action) -> bool {
 881        let target = self
 882            .focused()
 883            .and_then(|focused_handle| {
 884                self.window
 885                    .rendered_frame
 886                    .dispatch_tree
 887                    .focusable_node_id(focused_handle.id)
 888            })
 889            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
 890        self.window
 891            .rendered_frame
 892            .dispatch_tree
 893            .is_action_available(action, target)
 894    }
 895
 896    /// The position of the mouse relative to the window.
 897    pub fn mouse_position(&self) -> Point<Pixels> {
 898        self.window.mouse_position
 899    }
 900
 901    /// The current state of the keyboard's modifiers
 902    pub fn modifiers(&self) -> Modifiers {
 903        self.window.modifiers
 904    }
 905
 906    pub fn set_cursor_style(&mut self, style: CursorStyle) {
 907        self.window.requested_cursor_style = Some(style)
 908    }
 909
 910    /// Called during painting to invoke the given closure in a new stacking context. The given
 911    /// z-index is interpreted relative to the previous call to `stack`.
 912    pub fn with_z_index<R>(&mut self, z_index: u8, f: impl FnOnce(&mut Self) -> R) -> R {
 913        self.window.next_frame.z_index_stack.push(z_index);
 914        let result = f(self);
 915        self.window.next_frame.z_index_stack.pop();
 916        result
 917    }
 918
 919    /// Called during painting to track which z-index is on top at each pixel position
 920    pub fn add_opaque_layer(&mut self, bounds: Bounds<Pixels>) {
 921        let stacking_order = self.window.next_frame.z_index_stack.clone();
 922        let depth_map = &mut self.window.next_frame.depth_map;
 923        match depth_map.binary_search_by(|(level, _)| stacking_order.cmp(&level)) {
 924            Ok(i) | Err(i) => depth_map.insert(i, (stacking_order, bounds)),
 925        }
 926    }
 927
 928    /// Returns true if the top-most opaque layer painted over this point was part of the
 929    /// same layer as the given stacking order.
 930    pub fn was_top_layer(&self, point: &Point<Pixels>, level: &StackingOrder) -> bool {
 931        for (stack, bounds) in self.window.rendered_frame.depth_map.iter() {
 932            if bounds.contains(point) {
 933                return level.starts_with(stack) || stack.starts_with(level);
 934            }
 935        }
 936
 937        false
 938    }
 939
 940    pub fn was_top_layer_under_active_drag(
 941        &self,
 942        point: &Point<Pixels>,
 943        level: &StackingOrder,
 944    ) -> bool {
 945        for (stack, bounds) in self.window.rendered_frame.depth_map.iter() {
 946            if stack.starts_with(&[ACTIVE_DRAG_Z_INDEX]) {
 947                continue;
 948            }
 949            if bounds.contains(point) {
 950                return level.starts_with(stack) || stack.starts_with(level);
 951            }
 952        }
 953
 954        false
 955    }
 956
 957    /// Called during painting to get the current stacking order.
 958    pub fn stacking_order(&self) -> &StackingOrder {
 959        &self.window.next_frame.z_index_stack
 960    }
 961
 962    /// Paint one or more drop shadows into the scene for the next frame at the current z-index.
 963    pub fn paint_shadows(
 964        &mut self,
 965        bounds: Bounds<Pixels>,
 966        corner_radii: Corners<Pixels>,
 967        shadows: &[BoxShadow],
 968    ) {
 969        let scale_factor = self.scale_factor();
 970        let content_mask = self.content_mask();
 971        let window = &mut *self.window;
 972        for shadow in shadows {
 973            let mut shadow_bounds = bounds;
 974            shadow_bounds.origin += shadow.offset;
 975            shadow_bounds.dilate(shadow.spread_radius);
 976            window.next_frame.scene_builder.insert(
 977                &window.next_frame.z_index_stack,
 978                Shadow {
 979                    order: 0,
 980                    bounds: shadow_bounds.scale(scale_factor),
 981                    content_mask: content_mask.scale(scale_factor),
 982                    corner_radii: corner_radii.scale(scale_factor),
 983                    color: shadow.color,
 984                    blur_radius: shadow.blur_radius.scale(scale_factor),
 985                },
 986            );
 987        }
 988    }
 989
 990    /// Paint one or more quads into the scene for the next frame at the current stacking context.
 991    /// Quads are colored rectangular regions with an optional background, border, and corner radius.
 992    /// see [`fill`], [`outline`], and [`quad`] to construct this type.
 993    pub fn paint_quad(&mut self, quad: PaintQuad) {
 994        let scale_factor = self.scale_factor();
 995        let content_mask = self.content_mask();
 996
 997        let window = &mut *self.window;
 998        window.next_frame.scene_builder.insert(
 999            &window.next_frame.z_index_stack,
1000            Quad {
1001                order: 0,
1002                bounds: quad.bounds.scale(scale_factor),
1003                content_mask: content_mask.scale(scale_factor),
1004                background: quad.background,
1005                border_color: quad.border_color,
1006                corner_radii: quad.corner_radii.scale(scale_factor),
1007                border_widths: quad.border_widths.scale(scale_factor),
1008            },
1009        );
1010    }
1011
1012    /// Paint the given `Path` into the scene for the next frame at the current z-index.
1013    pub fn paint_path(&mut self, mut path: Path<Pixels>, color: impl Into<Hsla>) {
1014        let scale_factor = self.scale_factor();
1015        let content_mask = self.content_mask();
1016        path.content_mask = content_mask;
1017        path.color = color.into();
1018        let window = &mut *self.window;
1019        window
1020            .next_frame
1021            .scene_builder
1022            .insert(&window.next_frame.z_index_stack, path.scale(scale_factor));
1023    }
1024
1025    /// Paint an underline into the scene for the next frame at the current z-index.
1026    pub fn paint_underline(
1027        &mut self,
1028        origin: Point<Pixels>,
1029        width: Pixels,
1030        style: &UnderlineStyle,
1031    ) {
1032        let scale_factor = self.scale_factor();
1033        let height = if style.wavy {
1034            style.thickness * 3.
1035        } else {
1036            style.thickness
1037        };
1038        let bounds = Bounds {
1039            origin,
1040            size: size(width, height),
1041        };
1042        let content_mask = self.content_mask();
1043        let window = &mut *self.window;
1044        window.next_frame.scene_builder.insert(
1045            &window.next_frame.z_index_stack,
1046            Underline {
1047                order: 0,
1048                bounds: bounds.scale(scale_factor),
1049                content_mask: content_mask.scale(scale_factor),
1050                thickness: style.thickness.scale(scale_factor),
1051                color: style.color.unwrap_or_default(),
1052                wavy: style.wavy,
1053            },
1054        );
1055    }
1056
1057    /// Paint a monochrome (non-emoji) glyph into the scene for the next frame at the current z-index.
1058    /// The y component of the origin is the baseline of the glyph.
1059    pub fn paint_glyph(
1060        &mut self,
1061        origin: Point<Pixels>,
1062        font_id: FontId,
1063        glyph_id: GlyphId,
1064        font_size: Pixels,
1065        color: Hsla,
1066    ) -> Result<()> {
1067        let scale_factor = self.scale_factor();
1068        let glyph_origin = origin.scale(scale_factor);
1069        let subpixel_variant = Point {
1070            x: (glyph_origin.x.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
1071            y: (glyph_origin.y.0.fract() * SUBPIXEL_VARIANTS as f32).floor() as u8,
1072        };
1073        let params = RenderGlyphParams {
1074            font_id,
1075            glyph_id,
1076            font_size,
1077            subpixel_variant,
1078            scale_factor,
1079            is_emoji: false,
1080        };
1081
1082        let raster_bounds = self.text_system().raster_bounds(&params)?;
1083        if !raster_bounds.is_zero() {
1084            let tile =
1085                self.window
1086                    .sprite_atlas
1087                    .get_or_insert_with(&params.clone().into(), &mut || {
1088                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
1089                        Ok((size, Cow::Owned(bytes)))
1090                    })?;
1091            let bounds = Bounds {
1092                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
1093                size: tile.bounds.size.map(Into::into),
1094            };
1095            let content_mask = self.content_mask().scale(scale_factor);
1096            let window = &mut *self.window;
1097            window.next_frame.scene_builder.insert(
1098                &window.next_frame.z_index_stack,
1099                MonochromeSprite {
1100                    order: 0,
1101                    bounds,
1102                    content_mask,
1103                    color,
1104                    tile,
1105                },
1106            );
1107        }
1108        Ok(())
1109    }
1110
1111    /// Paint an emoji glyph into the scene for the next frame at the current z-index.
1112    /// The y component of the origin is the baseline of the glyph.
1113    pub fn paint_emoji(
1114        &mut self,
1115        origin: Point<Pixels>,
1116        font_id: FontId,
1117        glyph_id: GlyphId,
1118        font_size: Pixels,
1119    ) -> Result<()> {
1120        let scale_factor = self.scale_factor();
1121        let glyph_origin = origin.scale(scale_factor);
1122        let params = RenderGlyphParams {
1123            font_id,
1124            glyph_id,
1125            font_size,
1126            // We don't render emojis with subpixel variants.
1127            subpixel_variant: Default::default(),
1128            scale_factor,
1129            is_emoji: true,
1130        };
1131
1132        let raster_bounds = self.text_system().raster_bounds(&params)?;
1133        if !raster_bounds.is_zero() {
1134            let tile =
1135                self.window
1136                    .sprite_atlas
1137                    .get_or_insert_with(&params.clone().into(), &mut || {
1138                        let (size, bytes) = self.text_system().rasterize_glyph(&params)?;
1139                        Ok((size, Cow::Owned(bytes)))
1140                    })?;
1141            let bounds = Bounds {
1142                origin: glyph_origin.map(|px| px.floor()) + raster_bounds.origin.map(Into::into),
1143                size: tile.bounds.size.map(Into::into),
1144            };
1145            let content_mask = self.content_mask().scale(scale_factor);
1146            let window = &mut *self.window;
1147
1148            window.next_frame.scene_builder.insert(
1149                &window.next_frame.z_index_stack,
1150                PolychromeSprite {
1151                    order: 0,
1152                    bounds,
1153                    corner_radii: Default::default(),
1154                    content_mask,
1155                    tile,
1156                    grayscale: false,
1157                },
1158            );
1159        }
1160        Ok(())
1161    }
1162
1163    /// Paint a monochrome SVG into the scene for the next frame at the current stacking context.
1164    pub fn paint_svg(
1165        &mut self,
1166        bounds: Bounds<Pixels>,
1167        path: SharedString,
1168        color: Hsla,
1169    ) -> Result<()> {
1170        let scale_factor = self.scale_factor();
1171        let bounds = bounds.scale(scale_factor);
1172        // Render the SVG at twice the size to get a higher quality result.
1173        let params = RenderSvgParams {
1174            path,
1175            size: bounds
1176                .size
1177                .map(|pixels| DevicePixels::from((pixels.0 * 2.).ceil() as i32)),
1178        };
1179
1180        let tile =
1181            self.window
1182                .sprite_atlas
1183                .get_or_insert_with(&params.clone().into(), &mut || {
1184                    let bytes = self.svg_renderer.render(&params)?;
1185                    Ok((params.size, Cow::Owned(bytes)))
1186                })?;
1187        let content_mask = self.content_mask().scale(scale_factor);
1188
1189        let window = &mut *self.window;
1190        window.next_frame.scene_builder.insert(
1191            &window.next_frame.z_index_stack,
1192            MonochromeSprite {
1193                order: 0,
1194                bounds,
1195                content_mask,
1196                color,
1197                tile,
1198            },
1199        );
1200
1201        Ok(())
1202    }
1203
1204    /// Paint an image into the scene for the next frame at the current z-index.
1205    pub fn paint_image(
1206        &mut self,
1207        bounds: Bounds<Pixels>,
1208        corner_radii: Corners<Pixels>,
1209        data: Arc<ImageData>,
1210        grayscale: bool,
1211    ) -> Result<()> {
1212        let scale_factor = self.scale_factor();
1213        let bounds = bounds.scale(scale_factor);
1214        let params = RenderImageParams { image_id: data.id };
1215
1216        let tile = self
1217            .window
1218            .sprite_atlas
1219            .get_or_insert_with(&params.clone().into(), &mut || {
1220                Ok((data.size(), Cow::Borrowed(data.as_bytes())))
1221            })?;
1222        let content_mask = self.content_mask().scale(scale_factor);
1223        let corner_radii = corner_radii.scale(scale_factor);
1224
1225        let window = &mut *self.window;
1226        window.next_frame.scene_builder.insert(
1227            &window.next_frame.z_index_stack,
1228            PolychromeSprite {
1229                order: 0,
1230                bounds,
1231                content_mask,
1232                corner_radii,
1233                tile,
1234                grayscale,
1235            },
1236        );
1237        Ok(())
1238    }
1239
1240    /// Paint a surface into the scene for the next frame at the current z-index.
1241    pub fn paint_surface(&mut self, bounds: Bounds<Pixels>, image_buffer: CVImageBuffer) {
1242        let scale_factor = self.scale_factor();
1243        let bounds = bounds.scale(scale_factor);
1244        let content_mask = self.content_mask().scale(scale_factor);
1245        let window = &mut *self.window;
1246        window.next_frame.scene_builder.insert(
1247            &window.next_frame.z_index_stack,
1248            Surface {
1249                order: 0,
1250                bounds,
1251                content_mask,
1252                image_buffer,
1253            },
1254        );
1255    }
1256
1257    /// Draw pixels to the display for this window based on the contents of its scene.
1258    pub(crate) fn draw(&mut self) -> Scene {
1259        let t0 = std::time::Instant::now();
1260        self.window.dirty = false;
1261        self.window.drawing = true;
1262
1263        #[cfg(any(test, feature = "test-support"))]
1264        {
1265            self.window.focus_invalidated = false;
1266        }
1267
1268        self.text_system().start_frame();
1269        self.window.platform_window.clear_input_handler();
1270        self.window.layout_engine.as_mut().unwrap().clear();
1271        self.window.next_frame.clear();
1272        let root_view = self.window.root_view.take().unwrap();
1273
1274        self.with_z_index(0, |cx| {
1275            cx.with_key_dispatch(Some(KeyContext::default()), None, |_, cx| {
1276                for (action_type, action_listeners) in &cx.app.global_action_listeners {
1277                    for action_listener in action_listeners.iter().cloned() {
1278                        cx.window.next_frame.dispatch_tree.on_action(
1279                            *action_type,
1280                            Rc::new(move |action, phase, cx| action_listener(action, phase, cx)),
1281                        )
1282                    }
1283                }
1284
1285                let available_space = cx.window.viewport_size.map(Into::into);
1286                root_view.draw(Point::default(), available_space, cx);
1287            })
1288        });
1289
1290        if let Some(active_drag) = self.app.active_drag.take() {
1291            self.with_z_index(ACTIVE_DRAG_Z_INDEX, |cx| {
1292                let offset = cx.mouse_position() - active_drag.cursor_offset;
1293                let available_space = size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1294                active_drag.view.draw(offset, available_space, cx);
1295            });
1296            self.active_drag = Some(active_drag);
1297        } else if let Some(active_tooltip) = self.app.active_tooltip.take() {
1298            self.with_z_index(1, |cx| {
1299                let available_space = size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1300                active_tooltip
1301                    .view
1302                    .draw(active_tooltip.cursor_offset, available_space, cx);
1303            });
1304        }
1305
1306        self.window
1307            .next_frame
1308            .dispatch_tree
1309            .preserve_pending_keystrokes(
1310                &mut self.window.rendered_frame.dispatch_tree,
1311                self.window.focus,
1312            );
1313        self.window.next_frame.focus = self.window.focus;
1314        self.window.root_view = Some(root_view);
1315
1316        let previous_focus_path = self.window.rendered_frame.focus_path();
1317        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1318        let current_focus_path = self.window.rendered_frame.focus_path();
1319
1320        if previous_focus_path != current_focus_path {
1321            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1322                self.window
1323                    .blur_listeners
1324                    .clone()
1325                    .retain(&(), |listener| listener(self));
1326            }
1327
1328            let event = FocusEvent {
1329                previous_focus_path,
1330                current_focus_path,
1331            };
1332            self.window
1333                .focus_listeners
1334                .clone()
1335                .retain(&(), |listener| listener(&event, self));
1336        }
1337
1338        let scene = self.window.rendered_frame.scene_builder.build();
1339
1340        // Set the cursor only if we're the active window.
1341        let cursor_style = self
1342            .window
1343            .requested_cursor_style
1344            .take()
1345            .unwrap_or(CursorStyle::Arrow);
1346        if self.is_window_active() {
1347            self.platform.set_cursor_style(cursor_style);
1348        }
1349
1350        self.window.drawing = false;
1351        eprintln!("window draw: {:?}", t0.elapsed());
1352
1353        scene
1354    }
1355
1356    /// Dispatch a mouse or keyboard event on the window.
1357    pub fn dispatch_event(&mut self, event: InputEvent) -> bool {
1358        // Handlers may set this to false by calling `stop_propagation`.
1359        self.app.propagate_event = true;
1360        // Handlers may set this to true by calling `prevent_default`.
1361        self.window.default_prevented = false;
1362
1363        let event = match event {
1364            // Track the mouse position with our own state, since accessing the platform
1365            // API for the mouse position can only occur on the main thread.
1366            InputEvent::MouseMove(mouse_move) => {
1367                self.window.mouse_position = mouse_move.position;
1368                self.window.modifiers = mouse_move.modifiers;
1369                InputEvent::MouseMove(mouse_move)
1370            }
1371            InputEvent::MouseDown(mouse_down) => {
1372                self.window.mouse_position = mouse_down.position;
1373                self.window.modifiers = mouse_down.modifiers;
1374                InputEvent::MouseDown(mouse_down)
1375            }
1376            InputEvent::MouseUp(mouse_up) => {
1377                self.window.mouse_position = mouse_up.position;
1378                self.window.modifiers = mouse_up.modifiers;
1379                InputEvent::MouseUp(mouse_up)
1380            }
1381            InputEvent::MouseExited(mouse_exited) => {
1382                // todo!("Should we record that the mouse is outside of the window somehow? Or are these global pixels?")
1383                self.window.modifiers = mouse_exited.modifiers;
1384
1385                InputEvent::MouseExited(mouse_exited)
1386            }
1387            InputEvent::ModifiersChanged(modifiers_changed) => {
1388                self.window.modifiers = modifiers_changed.modifiers;
1389                InputEvent::ModifiersChanged(modifiers_changed)
1390            }
1391            InputEvent::ScrollWheel(scroll_wheel) => {
1392                self.window.mouse_position = scroll_wheel.position;
1393                self.window.modifiers = scroll_wheel.modifiers;
1394                InputEvent::ScrollWheel(scroll_wheel)
1395            }
1396            // Translate dragging and dropping of external files from the operating system
1397            // to internal drag and drop events.
1398            InputEvent::FileDrop(file_drop) => match file_drop {
1399                FileDropEvent::Entered { position, files } => {
1400                    self.window.mouse_position = position;
1401                    if self.active_drag.is_none() {
1402                        self.active_drag = Some(AnyDrag {
1403                            value: Box::new(files.clone()),
1404                            view: self.build_view(|_| files).into(),
1405                            cursor_offset: position,
1406                        });
1407                    }
1408                    InputEvent::MouseMove(MouseMoveEvent {
1409                        position,
1410                        pressed_button: Some(MouseButton::Left),
1411                        modifiers: Modifiers::default(),
1412                    })
1413                }
1414                FileDropEvent::Pending { position } => {
1415                    self.window.mouse_position = position;
1416                    InputEvent::MouseMove(MouseMoveEvent {
1417                        position,
1418                        pressed_button: Some(MouseButton::Left),
1419                        modifiers: Modifiers::default(),
1420                    })
1421                }
1422                FileDropEvent::Submit { position } => {
1423                    self.activate(true);
1424                    self.window.mouse_position = position;
1425                    InputEvent::MouseUp(MouseUpEvent {
1426                        button: MouseButton::Left,
1427                        position,
1428                        modifiers: Modifiers::default(),
1429                        click_count: 1,
1430                    })
1431                }
1432                FileDropEvent::Exited => InputEvent::MouseUp(MouseUpEvent {
1433                    button: MouseButton::Left,
1434                    position: Point::default(),
1435                    modifiers: Modifiers::default(),
1436                    click_count: 1,
1437                }),
1438            },
1439            InputEvent::KeyDown(_) | InputEvent::KeyUp(_) => event,
1440        };
1441
1442        if let Some(any_mouse_event) = event.mouse_event() {
1443            self.dispatch_mouse_event(any_mouse_event);
1444        } else if let Some(any_key_event) = event.keyboard_event() {
1445            self.dispatch_key_event(any_key_event);
1446        }
1447
1448        !self.app.propagate_event
1449    }
1450
1451    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1452        if let Some(mut handlers) = self
1453            .window
1454            .rendered_frame
1455            .mouse_listeners
1456            .remove(&event.type_id())
1457        {
1458            // Because handlers may add other handlers, we sort every time.
1459            handlers.sort_by(|(a, _), (b, _)| a.cmp(b));
1460
1461            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1462            // special purposes, such as detecting events outside of a given Bounds.
1463            for (_, handler) in &mut handlers {
1464                handler(event, DispatchPhase::Capture, self);
1465                if !self.app.propagate_event {
1466                    break;
1467                }
1468            }
1469
1470            // Bubble phase, where most normal handlers do their work.
1471            if self.app.propagate_event {
1472                for (_, handler) in handlers.iter_mut().rev() {
1473                    handler(event, DispatchPhase::Bubble, self);
1474                    if !self.app.propagate_event {
1475                        break;
1476                    }
1477                }
1478            }
1479
1480            if self.app.propagate_event && event.downcast_ref::<MouseUpEvent>().is_some() {
1481                self.active_drag = None;
1482            }
1483
1484            self.window
1485                .rendered_frame
1486                .mouse_listeners
1487                .insert(event.type_id(), handlers);
1488        }
1489    }
1490
1491    fn dispatch_key_event(&mut self, event: &dyn Any) {
1492        let node_id = self
1493            .window
1494            .focus
1495            .and_then(|focus_id| {
1496                self.window
1497                    .rendered_frame
1498                    .dispatch_tree
1499                    .focusable_node_id(focus_id)
1500            })
1501            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1502
1503        let dispatch_path = self
1504            .window
1505            .rendered_frame
1506            .dispatch_tree
1507            .dispatch_path(node_id);
1508
1509        let mut actions: Vec<Box<dyn Action>> = Vec::new();
1510
1511        // Capture phase
1512        let mut context_stack: SmallVec<[KeyContext; 16]> = SmallVec::new();
1513        self.propagate_event = true;
1514
1515        for node_id in &dispatch_path {
1516            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1517
1518            if let Some(context) = node.context.clone() {
1519                context_stack.push(context);
1520            }
1521
1522            for key_listener in node.key_listeners.clone() {
1523                key_listener(event, DispatchPhase::Capture, self);
1524                if !self.propagate_event {
1525                    return;
1526                }
1527            }
1528        }
1529
1530        // Bubble phase
1531        for node_id in dispatch_path.iter().rev() {
1532            // Handle low level key events
1533            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1534            for key_listener in node.key_listeners.clone() {
1535                key_listener(event, DispatchPhase::Bubble, self);
1536                if !self.propagate_event {
1537                    return;
1538                }
1539            }
1540
1541            // Match keystrokes
1542            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1543            if node.context.is_some() {
1544                if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1545                    let mut new_actions = self
1546                        .window
1547                        .rendered_frame
1548                        .dispatch_tree
1549                        .dispatch_key(&key_down_event.keystroke, &context_stack);
1550                    actions.append(&mut new_actions);
1551                }
1552
1553                context_stack.pop();
1554            }
1555        }
1556
1557        for action in actions {
1558            self.dispatch_action_on_node(node_id, action.boxed_clone());
1559            if !self.propagate_event {
1560                self.dispatch_keystroke_observers(event, Some(action));
1561                return;
1562            }
1563        }
1564        self.dispatch_keystroke_observers(event, None);
1565    }
1566
1567    pub fn has_pending_keystrokes(&self) -> bool {
1568        self.window
1569            .rendered_frame
1570            .dispatch_tree
1571            .has_pending_keystrokes()
1572    }
1573
1574    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: Box<dyn Action>) {
1575        let dispatch_path = self
1576            .window
1577            .rendered_frame
1578            .dispatch_tree
1579            .dispatch_path(node_id);
1580
1581        // Capture phase
1582        for node_id in &dispatch_path {
1583            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1584            for DispatchActionListener {
1585                action_type,
1586                listener,
1587            } in node.action_listeners.clone()
1588            {
1589                let any_action = action.as_any();
1590                if action_type == any_action.type_id() {
1591                    listener(any_action, DispatchPhase::Capture, self);
1592                    if !self.propagate_event {
1593                        return;
1594                    }
1595                }
1596            }
1597        }
1598        // Bubble phase
1599        for node_id in dispatch_path.iter().rev() {
1600            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1601            for DispatchActionListener {
1602                action_type,
1603                listener,
1604            } in node.action_listeners.clone()
1605            {
1606                let any_action = action.as_any();
1607                if action_type == any_action.type_id() {
1608                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1609                    listener(any_action, DispatchPhase::Bubble, self);
1610                    if !self.propagate_event {
1611                        return;
1612                    }
1613                }
1614            }
1615        }
1616    }
1617
1618    /// Register the given handler to be invoked whenever the global of the given type
1619    /// is updated.
1620    pub fn observe_global<G: 'static>(
1621        &mut self,
1622        f: impl Fn(&mut WindowContext<'_>) + 'static,
1623    ) -> Subscription {
1624        let window_handle = self.window.handle;
1625        let (subscription, activate) = self.global_observers.insert(
1626            TypeId::of::<G>(),
1627            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1628        );
1629        self.app.defer(move |_| activate());
1630        subscription
1631    }
1632
1633    pub fn activate_window(&self) {
1634        self.window.platform_window.activate();
1635    }
1636
1637    pub fn minimize_window(&self) {
1638        self.window.platform_window.minimize();
1639    }
1640
1641    pub fn toggle_full_screen(&self) {
1642        self.window.platform_window.toggle_full_screen();
1643    }
1644
1645    pub fn prompt(
1646        &self,
1647        level: PromptLevel,
1648        msg: &str,
1649        answers: &[&str],
1650    ) -> oneshot::Receiver<usize> {
1651        self.window.platform_window.prompt(level, msg, answers)
1652    }
1653
1654    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1655        let node_id = self
1656            .window
1657            .focus
1658            .and_then(|focus_id| {
1659                self.window
1660                    .rendered_frame
1661                    .dispatch_tree
1662                    .focusable_node_id(focus_id)
1663            })
1664            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1665
1666        self.window
1667            .rendered_frame
1668            .dispatch_tree
1669            .available_actions(node_id)
1670    }
1671
1672    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1673        self.window
1674            .rendered_frame
1675            .dispatch_tree
1676            .bindings_for_action(
1677                action,
1678                &self.window.rendered_frame.dispatch_tree.context_stack,
1679            )
1680    }
1681
1682    pub fn bindings_for_action_in(
1683        &self,
1684        action: &dyn Action,
1685        focus_handle: &FocusHandle,
1686    ) -> Vec<KeyBinding> {
1687        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1688
1689        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1690            return vec![];
1691        };
1692        let context_stack = dispatch_tree
1693            .dispatch_path(node_id)
1694            .into_iter()
1695            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1696            .collect();
1697        dispatch_tree.bindings_for_action(action, &context_stack)
1698    }
1699
1700    pub fn listener_for<V: Render, E>(
1701        &self,
1702        view: &View<V>,
1703        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1704    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1705        let view = view.downgrade();
1706        move |e: &E, cx: &mut WindowContext| {
1707            view.update(cx, |view, cx| f(view, e, cx)).ok();
1708        }
1709    }
1710
1711    pub fn handler_for<V: Render>(
1712        &self,
1713        view: &View<V>,
1714        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1715    ) -> impl Fn(&mut WindowContext) {
1716        let view = view.downgrade();
1717        move |cx: &mut WindowContext| {
1718            view.update(cx, |view, cx| f(view, cx)).ok();
1719        }
1720    }
1721
1722    //========== ELEMENT RELATED FUNCTIONS ===========
1723    pub fn with_key_dispatch<R>(
1724        &mut self,
1725        context: Option<KeyContext>,
1726        focus_handle: Option<FocusHandle>,
1727        f: impl FnOnce(Option<FocusHandle>, &mut Self) -> R,
1728    ) -> R {
1729        let window = &mut self.window;
1730        window.next_frame.dispatch_tree.push_node(context.clone());
1731        if let Some(focus_handle) = focus_handle.as_ref() {
1732            window
1733                .next_frame
1734                .dispatch_tree
1735                .make_focusable(focus_handle.id);
1736        }
1737        let result = f(focus_handle, self);
1738
1739        self.window.next_frame.dispatch_tree.pop_node();
1740
1741        result
1742    }
1743
1744    /// Set an input handler, such as [ElementInputHandler], which interfaces with the
1745    /// platform to receive textual input with proper integration with concerns such
1746    /// as IME interactions.
1747    pub fn handle_input(
1748        &mut self,
1749        focus_handle: &FocusHandle,
1750        input_handler: impl PlatformInputHandler,
1751    ) {
1752        if focus_handle.is_focused(self) {
1753            self.window
1754                .platform_window
1755                .set_input_handler(Box::new(input_handler));
1756        }
1757    }
1758
1759    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1760        let mut this = self.to_async();
1761        self.window
1762            .platform_window
1763            .on_should_close(Box::new(move || this.update(|_, cx| f(cx)).unwrap_or(true)))
1764    }
1765}
1766
1767impl Context for WindowContext<'_> {
1768    type Result<T> = T;
1769
1770    fn build_model<T>(
1771        &mut self,
1772        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
1773    ) -> Model<T>
1774    where
1775        T: 'static,
1776    {
1777        let slot = self.app.entities.reserve();
1778        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1779        self.entities.insert(slot, model)
1780    }
1781
1782    fn update_model<T: 'static, R>(
1783        &mut self,
1784        model: &Model<T>,
1785        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1786    ) -> R {
1787        let mut entity = self.entities.lease(model);
1788        let result = update(
1789            &mut *entity,
1790            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1791        );
1792        self.entities.end_lease(entity);
1793        result
1794    }
1795
1796    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1797    where
1798        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1799    {
1800        if window == self.window.handle {
1801            let root_view = self.window.root_view.clone().unwrap();
1802            Ok(update(root_view, self))
1803        } else {
1804            window.update(self.app, update)
1805        }
1806    }
1807
1808    fn read_model<T, R>(
1809        &self,
1810        handle: &Model<T>,
1811        read: impl FnOnce(&T, &AppContext) -> R,
1812    ) -> Self::Result<R>
1813    where
1814        T: 'static,
1815    {
1816        let entity = self.entities.read(handle);
1817        read(&*entity, &*self.app)
1818    }
1819
1820    fn read_window<T, R>(
1821        &self,
1822        window: &WindowHandle<T>,
1823        read: impl FnOnce(View<T>, &AppContext) -> R,
1824    ) -> Result<R>
1825    where
1826        T: 'static,
1827    {
1828        if window.any_handle == self.window.handle {
1829            let root_view = self
1830                .window
1831                .root_view
1832                .clone()
1833                .unwrap()
1834                .downcast::<T>()
1835                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1836            Ok(read(root_view, self))
1837        } else {
1838            self.app.read_window(window, read)
1839        }
1840    }
1841}
1842
1843impl VisualContext for WindowContext<'_> {
1844    fn build_view<V>(
1845        &mut self,
1846        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1847    ) -> Self::Result<View<V>>
1848    where
1849        V: 'static + Render,
1850    {
1851        let slot = self.app.entities.reserve();
1852        let view = View {
1853            model: slot.clone(),
1854        };
1855        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1856        let entity = build_view_state(&mut cx);
1857        cx.entities.insert(slot, entity);
1858
1859        cx.new_view_observers
1860            .clone()
1861            .retain(&TypeId::of::<V>(), |observer| {
1862                let any_view = AnyView::from(view.clone());
1863                (observer)(any_view, self);
1864                true
1865            });
1866
1867        view
1868    }
1869
1870    /// Update the given view. Prefer calling `View::update` instead, which calls this method.
1871    fn update_view<T: 'static, R>(
1872        &mut self,
1873        view: &View<T>,
1874        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1875    ) -> Self::Result<R> {
1876        let mut lease = self.app.entities.lease(&view.model);
1877        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1878        let result = update(&mut *lease, &mut cx);
1879        cx.app.entities.end_lease(lease);
1880        result
1881    }
1882
1883    fn replace_root_view<V>(
1884        &mut self,
1885        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1886    ) -> Self::Result<View<V>>
1887    where
1888        V: 'static + Render,
1889    {
1890        let slot = self.app.entities.reserve();
1891        let view = View {
1892            model: slot.clone(),
1893        };
1894        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1895        let entity = build_view(&mut cx);
1896        self.entities.insert(slot, entity);
1897        self.window.root_view = Some(view.clone().into());
1898        view
1899    }
1900
1901    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1902        self.update_view(view, |view, cx| {
1903            view.focus_handle(cx).clone().focus(cx);
1904        })
1905    }
1906
1907    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1908    where
1909        V: ManagedView,
1910    {
1911        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1912    }
1913}
1914
1915impl<'a> std::ops::Deref for WindowContext<'a> {
1916    type Target = AppContext;
1917
1918    fn deref(&self) -> &Self::Target {
1919        &self.app
1920    }
1921}
1922
1923impl<'a> std::ops::DerefMut for WindowContext<'a> {
1924    fn deref_mut(&mut self) -> &mut Self::Target {
1925        &mut self.app
1926    }
1927}
1928
1929impl<'a> Borrow<AppContext> for WindowContext<'a> {
1930    fn borrow(&self) -> &AppContext {
1931        &self.app
1932    }
1933}
1934
1935impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1936    fn borrow_mut(&mut self) -> &mut AppContext {
1937        &mut self.app
1938    }
1939}
1940
1941pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1942    fn app_mut(&mut self) -> &mut AppContext {
1943        self.borrow_mut()
1944    }
1945
1946    fn app(&self) -> &AppContext {
1947        self.borrow()
1948    }
1949
1950    fn window(&self) -> &Window {
1951        self.borrow()
1952    }
1953
1954    fn window_mut(&mut self) -> &mut Window {
1955        self.borrow_mut()
1956    }
1957
1958    /// Pushes the given element id onto the global stack and invokes the given closure
1959    /// with a `GlobalElementId`, which disambiguates the given id in the context of its ancestor
1960    /// ids. Because elements are discarded and recreated on each frame, the `GlobalElementId` is
1961    /// used to associate state with identified elements across separate frames.
1962    fn with_element_id<R>(
1963        &mut self,
1964        id: Option<impl Into<ElementId>>,
1965        f: impl FnOnce(&mut Self) -> R,
1966    ) -> R {
1967        if let Some(id) = id.map(Into::into) {
1968            let window = self.window_mut();
1969            window.element_id_stack.push(id.into());
1970            let result = f(self);
1971            let window: &mut Window = self.borrow_mut();
1972            window.element_id_stack.pop();
1973            result
1974        } else {
1975            f(self)
1976        }
1977    }
1978
1979    /// Invoke the given function with the given content mask after intersecting it
1980    /// with the current mask.
1981    fn with_content_mask<R>(
1982        &mut self,
1983        mask: Option<ContentMask<Pixels>>,
1984        f: impl FnOnce(&mut Self) -> R,
1985    ) -> R {
1986        if let Some(mask) = mask {
1987            let mask = mask.intersect(&self.content_mask());
1988            self.window_mut().next_frame.content_mask_stack.push(mask);
1989            let result = f(self);
1990            self.window_mut().next_frame.content_mask_stack.pop();
1991            result
1992        } else {
1993            f(self)
1994        }
1995    }
1996
1997    /// Invoke the given function with the content mask reset to that
1998    /// of the window.
1999    fn break_content_mask<R>(&mut self, f: impl FnOnce(&mut Self) -> R) -> R {
2000        let mask = ContentMask {
2001            bounds: Bounds {
2002                origin: Point::default(),
2003                size: self.window().viewport_size,
2004            },
2005        };
2006        self.window_mut().next_frame.content_mask_stack.push(mask);
2007        let result = f(self);
2008        self.window_mut().next_frame.content_mask_stack.pop();
2009        result
2010    }
2011
2012    /// Update the global element offset relative to the current offset. This is used to implement
2013    /// scrolling.
2014    fn with_element_offset<R>(
2015        &mut self,
2016        offset: Point<Pixels>,
2017        f: impl FnOnce(&mut Self) -> R,
2018    ) -> R {
2019        if offset.is_zero() {
2020            return f(self);
2021        };
2022
2023        let abs_offset = self.element_offset() + offset;
2024        self.with_absolute_element_offset(abs_offset, f)
2025    }
2026
2027    /// Update the global element offset based on the given offset. This is used to implement
2028    /// drag handles and other manual painting of elements.
2029    fn with_absolute_element_offset<R>(
2030        &mut self,
2031        offset: Point<Pixels>,
2032        f: impl FnOnce(&mut Self) -> R,
2033    ) -> R {
2034        self.window_mut()
2035            .next_frame
2036            .element_offset_stack
2037            .push(offset);
2038        let result = f(self);
2039        self.window_mut().next_frame.element_offset_stack.pop();
2040        result
2041    }
2042
2043    /// Obtain the current element offset.
2044    fn element_offset(&self) -> Point<Pixels> {
2045        self.window()
2046            .next_frame
2047            .element_offset_stack
2048            .last()
2049            .copied()
2050            .unwrap_or_default()
2051    }
2052
2053    /// Update or initialize state for an element with the given id that lives across multiple
2054    /// frames. If an element with this id existed in the rendered frame, its state will be passed
2055    /// to the given closure. The state returned by the closure will be stored so it can be referenced
2056    /// when drawing the next frame.
2057    fn with_element_state<S, R>(
2058        &mut self,
2059        id: ElementId,
2060        f: impl FnOnce(Option<S>, &mut Self) -> (R, S),
2061    ) -> R
2062    where
2063        S: 'static,
2064    {
2065        self.with_element_id(Some(id), |cx| {
2066            let global_id = cx.window().element_id_stack.clone();
2067
2068            if let Some(any) = cx
2069                .window_mut()
2070                .next_frame
2071                .element_states
2072                .remove(&global_id)
2073                .or_else(|| {
2074                    cx.window_mut()
2075                        .rendered_frame
2076                        .element_states
2077                        .remove(&global_id)
2078                })
2079            {
2080                let ElementStateBox {
2081                    inner,
2082
2083                    #[cfg(debug_assertions)]
2084                    type_name
2085                } = any;
2086                // Using the extra inner option to avoid needing to reallocate a new box.
2087                let mut state_box = inner
2088                    .downcast::<Option<S>>()
2089                    .map_err(|_| {
2090                        #[cfg(debug_assertions)]
2091                        {
2092                            anyhow!(
2093                                "invalid element state type for id, requested_type {:?}, actual type: {:?}",
2094                                std::any::type_name::<S>(),
2095                                type_name
2096                            )
2097                        }
2098
2099                        #[cfg(not(debug_assertions))]
2100                        {
2101                            anyhow!(
2102                                "invalid element state type for id, requested_type {:?}",
2103                                std::any::type_name::<S>(),
2104                            )
2105                        }
2106                    })
2107                    .unwrap();
2108
2109                // Actual: Option<AnyElement> <- View
2110                // Requested: () <- AnyElemet
2111                let state = state_box
2112                    .take()
2113                    .expect("element state is already on the stack");
2114                let (result, state) = f(Some(state), cx);
2115                state_box.replace(state);
2116                cx.window_mut()
2117                    .next_frame
2118                    .element_states
2119                    .insert(global_id, ElementStateBox {
2120                        inner: state_box,
2121
2122                        #[cfg(debug_assertions)]
2123                        type_name
2124                    });
2125                result
2126            } else {
2127                let (result, state) = f(None, cx);
2128                cx.window_mut()
2129                    .next_frame
2130                    .element_states
2131                    .insert(global_id,
2132                        ElementStateBox {
2133                            inner: Box::new(Some(state)),
2134
2135                            #[cfg(debug_assertions)]
2136                            type_name: std::any::type_name::<S>()
2137                        }
2138
2139                    );
2140                result
2141            }
2142        })
2143    }
2144
2145    /// Obtain the current content mask.
2146    fn content_mask(&self) -> ContentMask<Pixels> {
2147        self.window()
2148            .next_frame
2149            .content_mask_stack
2150            .last()
2151            .cloned()
2152            .unwrap_or_else(|| ContentMask {
2153                bounds: Bounds {
2154                    origin: Point::default(),
2155                    size: self.window().viewport_size,
2156                },
2157            })
2158    }
2159
2160    /// The size of an em for the base font of the application. Adjusting this value allows the
2161    /// UI to scale, just like zooming a web page.
2162    fn rem_size(&self) -> Pixels {
2163        self.window().rem_size
2164    }
2165}
2166
2167impl Borrow<Window> for WindowContext<'_> {
2168    fn borrow(&self) -> &Window {
2169        &self.window
2170    }
2171}
2172
2173impl BorrowMut<Window> for WindowContext<'_> {
2174    fn borrow_mut(&mut self) -> &mut Window {
2175        &mut self.window
2176    }
2177}
2178
2179impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
2180
2181pub struct ViewContext<'a, V> {
2182    window_cx: WindowContext<'a>,
2183    view: &'a View<V>,
2184}
2185
2186impl<V> Borrow<AppContext> for ViewContext<'_, V> {
2187    fn borrow(&self) -> &AppContext {
2188        &*self.window_cx.app
2189    }
2190}
2191
2192impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
2193    fn borrow_mut(&mut self) -> &mut AppContext {
2194        &mut *self.window_cx.app
2195    }
2196}
2197
2198impl<V> Borrow<Window> for ViewContext<'_, V> {
2199    fn borrow(&self) -> &Window {
2200        &*self.window_cx.window
2201    }
2202}
2203
2204impl<V> BorrowMut<Window> for ViewContext<'_, V> {
2205    fn borrow_mut(&mut self) -> &mut Window {
2206        &mut *self.window_cx.window
2207    }
2208}
2209
2210impl<'a, V: 'static> ViewContext<'a, V> {
2211    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
2212        Self {
2213            window_cx: WindowContext::new(app, window),
2214            view,
2215        }
2216    }
2217
2218    pub fn entity_id(&self) -> EntityId {
2219        self.view.entity_id()
2220    }
2221
2222    pub fn view(&self) -> &View<V> {
2223        self.view
2224    }
2225
2226    pub fn model(&self) -> &Model<V> {
2227        &self.view.model
2228    }
2229
2230    /// Access the underlying window context.
2231    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2232        &mut self.window_cx
2233    }
2234
2235    pub fn with_z_index<R>(&mut self, z_index: u8, f: impl FnOnce(&mut Self) -> R) -> R {
2236        self.window.next_frame.z_index_stack.push(z_index);
2237        let result = f(self);
2238        self.window.next_frame.z_index_stack.pop();
2239        result
2240    }
2241
2242    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
2243    where
2244        V: 'static,
2245    {
2246        let view = self.view().clone();
2247        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
2248    }
2249
2250    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
2251    /// that are currently on the stack to be returned to the app.
2252    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
2253        let view = self.view().downgrade();
2254        self.window_cx.defer(move |cx| {
2255            view.update(cx, f).ok();
2256        });
2257    }
2258
2259    pub fn observe<V2, E>(
2260        &mut self,
2261        entity: &E,
2262        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
2263    ) -> Subscription
2264    where
2265        V2: 'static,
2266        V: 'static,
2267        E: Entity<V2>,
2268    {
2269        let view = self.view().downgrade();
2270        let entity_id = entity.entity_id();
2271        let entity = entity.downgrade();
2272        let window_handle = self.window.handle;
2273        let (subscription, activate) = self.app.observers.insert(
2274            entity_id,
2275            Box::new(move |cx| {
2276                window_handle
2277                    .update(cx, |_, cx| {
2278                        if let Some(handle) = E::upgrade_from(&entity) {
2279                            view.update(cx, |this, cx| on_notify(this, handle, cx))
2280                                .is_ok()
2281                        } else {
2282                            false
2283                        }
2284                    })
2285                    .unwrap_or(false)
2286            }),
2287        );
2288        self.app.defer(move |_| activate());
2289        subscription
2290    }
2291
2292    pub fn subscribe<V2, E, Evt>(
2293        &mut self,
2294        entity: &E,
2295        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2296    ) -> Subscription
2297    where
2298        V2: EventEmitter<Evt>,
2299        E: Entity<V2>,
2300        Evt: 'static,
2301    {
2302        let view = self.view().downgrade();
2303        let entity_id = entity.entity_id();
2304        let handle = entity.downgrade();
2305        let window_handle = self.window.handle;
2306        let (subscription, activate) = self.app.event_listeners.insert(
2307            entity_id,
2308            (
2309                TypeId::of::<Evt>(),
2310                Box::new(move |event, cx| {
2311                    window_handle
2312                        .update(cx, |_, cx| {
2313                            if let Some(handle) = E::upgrade_from(&handle) {
2314                                let event = event.downcast_ref().expect("invalid event type");
2315                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2316                                    .is_ok()
2317                            } else {
2318                                false
2319                            }
2320                        })
2321                        .unwrap_or(false)
2322                }),
2323            ),
2324        );
2325        self.app.defer(move |_| activate());
2326        subscription
2327    }
2328
2329    pub fn on_release(
2330        &mut self,
2331        on_release: impl FnOnce(&mut V, &mut WindowContext) + 'static,
2332    ) -> Subscription {
2333        let window_handle = self.window.handle;
2334        let (subscription, activate) = self.app.release_listeners.insert(
2335            self.view.model.entity_id,
2336            Box::new(move |this, cx| {
2337                let this = this.downcast_mut().expect("invalid entity type");
2338                let _ = window_handle.update(cx, |_, cx| on_release(this, cx));
2339            }),
2340        );
2341        activate();
2342        subscription
2343    }
2344
2345    pub fn observe_release<V2, E>(
2346        &mut self,
2347        entity: &E,
2348        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2349    ) -> Subscription
2350    where
2351        V: 'static,
2352        V2: 'static,
2353        E: Entity<V2>,
2354    {
2355        let view = self.view().downgrade();
2356        let entity_id = entity.entity_id();
2357        let window_handle = self.window.handle;
2358        let (subscription, activate) = self.app.release_listeners.insert(
2359            entity_id,
2360            Box::new(move |entity, cx| {
2361                let entity = entity.downcast_mut().expect("invalid entity type");
2362                let _ = window_handle.update(cx, |_, cx| {
2363                    view.update(cx, |this, cx| on_release(this, entity, cx))
2364                });
2365            }),
2366        );
2367        activate();
2368        subscription
2369    }
2370
2371    pub fn notify(&mut self) {
2372        if !self.window.drawing {
2373            self.window_cx.notify();
2374            self.window_cx.app.push_effect(Effect::Notify {
2375                emitter: self.view.model.entity_id,
2376            });
2377        }
2378    }
2379
2380    pub fn observe_window_bounds(
2381        &mut self,
2382        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2383    ) -> Subscription {
2384        let view = self.view.downgrade();
2385        let (subscription, activate) = self.window.bounds_observers.insert(
2386            (),
2387            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2388        );
2389        activate();
2390        subscription
2391    }
2392
2393    pub fn observe_window_activation(
2394        &mut self,
2395        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2396    ) -> Subscription {
2397        let view = self.view.downgrade();
2398        let (subscription, activate) = self.window.activation_observers.insert(
2399            (),
2400            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2401        );
2402        activate();
2403        subscription
2404    }
2405
2406    /// Register a listener to be called when the given focus handle receives focus.
2407    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2408    /// is dropped.
2409    pub fn on_focus(
2410        &mut self,
2411        handle: &FocusHandle,
2412        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2413    ) -> Subscription {
2414        let view = self.view.downgrade();
2415        let focus_id = handle.id;
2416        let (subscription, activate) = self.window.focus_listeners.insert(
2417            (),
2418            Box::new(move |event, cx| {
2419                view.update(cx, |view, cx| {
2420                    if event.previous_focus_path.last() != Some(&focus_id)
2421                        && event.current_focus_path.last() == Some(&focus_id)
2422                    {
2423                        listener(view, cx)
2424                    }
2425                })
2426                .is_ok()
2427            }),
2428        );
2429        self.app.defer(move |_| activate());
2430        subscription
2431    }
2432
2433    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2434    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2435    /// is dropped.
2436    pub fn on_focus_in(
2437        &mut self,
2438        handle: &FocusHandle,
2439        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2440    ) -> Subscription {
2441        let view = self.view.downgrade();
2442        let focus_id = handle.id;
2443        let (subscription, activate) = self.window.focus_listeners.insert(
2444            (),
2445            Box::new(move |event, cx| {
2446                view.update(cx, |view, cx| {
2447                    if !event.previous_focus_path.contains(&focus_id)
2448                        && event.current_focus_path.contains(&focus_id)
2449                    {
2450                        listener(view, cx)
2451                    }
2452                })
2453                .is_ok()
2454            }),
2455        );
2456        self.app.defer(move |_| activate());
2457        subscription
2458    }
2459
2460    /// Register a listener to be called when the given focus handle loses focus.
2461    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2462    /// is dropped.
2463    pub fn on_blur(
2464        &mut self,
2465        handle: &FocusHandle,
2466        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2467    ) -> Subscription {
2468        let view = self.view.downgrade();
2469        let focus_id = handle.id;
2470        let (subscription, activate) = self.window.focus_listeners.insert(
2471            (),
2472            Box::new(move |event, cx| {
2473                view.update(cx, |view, cx| {
2474                    if event.previous_focus_path.last() == Some(&focus_id)
2475                        && event.current_focus_path.last() != Some(&focus_id)
2476                    {
2477                        listener(view, cx)
2478                    }
2479                })
2480                .is_ok()
2481            }),
2482        );
2483        self.app.defer(move |_| activate());
2484        subscription
2485    }
2486
2487    /// Register a listener to be called when the window loses focus.
2488    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2489    /// is dropped.
2490    pub fn on_blur_window(
2491        &mut self,
2492        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2493    ) -> Subscription {
2494        let view = self.view.downgrade();
2495        let (subscription, activate) = self.window.blur_listeners.insert(
2496            (),
2497            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2498        );
2499        activate();
2500        subscription
2501    }
2502
2503    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2504    /// Unlike [on_focus_changed], returns a subscription and persists until the subscription
2505    /// is dropped.
2506    pub fn on_focus_out(
2507        &mut self,
2508        handle: &FocusHandle,
2509        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2510    ) -> Subscription {
2511        let view = self.view.downgrade();
2512        let focus_id = handle.id;
2513        let (subscription, activate) = self.window.focus_listeners.insert(
2514            (),
2515            Box::new(move |event, cx| {
2516                view.update(cx, |view, cx| {
2517                    if event.previous_focus_path.contains(&focus_id)
2518                        && !event.current_focus_path.contains(&focus_id)
2519                    {
2520                        listener(view, cx)
2521                    }
2522                })
2523                .is_ok()
2524            }),
2525        );
2526        self.app.defer(move |_| activate());
2527        subscription
2528    }
2529
2530    pub fn spawn<Fut, R>(
2531        &mut self,
2532        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2533    ) -> Task<R>
2534    where
2535        R: 'static,
2536        Fut: Future<Output = R> + 'static,
2537    {
2538        let view = self.view().downgrade();
2539        self.window_cx.spawn(|cx| f(view, cx))
2540    }
2541
2542    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2543    where
2544        G: 'static,
2545    {
2546        let mut global = self.app.lease_global::<G>();
2547        let result = f(&mut global, self);
2548        self.app.end_global_lease(global);
2549        result
2550    }
2551
2552    pub fn observe_global<G: 'static>(
2553        &mut self,
2554        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2555    ) -> Subscription {
2556        let window_handle = self.window.handle;
2557        let view = self.view().downgrade();
2558        let (subscription, activate) = self.global_observers.insert(
2559            TypeId::of::<G>(),
2560            Box::new(move |cx| {
2561                window_handle
2562                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2563                    .unwrap_or(false)
2564            }),
2565        );
2566        self.app.defer(move |_| activate());
2567        subscription
2568    }
2569
2570    pub fn on_mouse_event<Event: 'static>(
2571        &mut self,
2572        handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
2573    ) {
2574        let handle = self.view().clone();
2575        self.window_cx.on_mouse_event(move |event, phase, cx| {
2576            handle.update(cx, |view, cx| {
2577                handler(view, event, phase, cx);
2578            })
2579        });
2580    }
2581
2582    pub fn on_key_event<Event: 'static>(
2583        &mut self,
2584        handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
2585    ) {
2586        let handle = self.view().clone();
2587        self.window_cx.on_key_event(move |event, phase, cx| {
2588            handle.update(cx, |view, cx| {
2589                handler(view, event, phase, cx);
2590            })
2591        });
2592    }
2593
2594    pub fn on_action(
2595        &mut self,
2596        action_type: TypeId,
2597        handler: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2598    ) {
2599        let handle = self.view().clone();
2600        self.window_cx
2601            .on_action(action_type, move |action, phase, cx| {
2602                handle.update(cx, |view, cx| {
2603                    handler(view, action, phase, cx);
2604                })
2605            });
2606    }
2607
2608    pub fn emit<Evt>(&mut self, event: Evt)
2609    where
2610        Evt: 'static,
2611        V: EventEmitter<Evt>,
2612    {
2613        let emitter = self.view.model.entity_id;
2614        self.app.push_effect(Effect::Emit {
2615            emitter,
2616            event_type: TypeId::of::<Evt>(),
2617            event: Box::new(event),
2618        });
2619    }
2620
2621    pub fn focus_self(&mut self)
2622    where
2623        V: FocusableView,
2624    {
2625        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2626    }
2627
2628    pub fn dismiss_self(&mut self)
2629    where
2630        V: ManagedView,
2631    {
2632        self.defer(|_, cx| cx.emit(DismissEvent))
2633    }
2634
2635    pub fn listener<E>(
2636        &self,
2637        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2638    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2639        let view = self.view().downgrade();
2640        move |e: &E, cx: &mut WindowContext| {
2641            view.update(cx, |view, cx| f(view, e, cx)).ok();
2642        }
2643    }
2644}
2645
2646impl<V> Context for ViewContext<'_, V> {
2647    type Result<U> = U;
2648
2649    fn build_model<T: 'static>(
2650        &mut self,
2651        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2652    ) -> Model<T> {
2653        self.window_cx.build_model(build_model)
2654    }
2655
2656    fn update_model<T: 'static, R>(
2657        &mut self,
2658        model: &Model<T>,
2659        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2660    ) -> R {
2661        self.window_cx.update_model(model, update)
2662    }
2663
2664    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2665    where
2666        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2667    {
2668        self.window_cx.update_window(window, update)
2669    }
2670
2671    fn read_model<T, R>(
2672        &self,
2673        handle: &Model<T>,
2674        read: impl FnOnce(&T, &AppContext) -> R,
2675    ) -> Self::Result<R>
2676    where
2677        T: 'static,
2678    {
2679        self.window_cx.read_model(handle, read)
2680    }
2681
2682    fn read_window<T, R>(
2683        &self,
2684        window: &WindowHandle<T>,
2685        read: impl FnOnce(View<T>, &AppContext) -> R,
2686    ) -> Result<R>
2687    where
2688        T: 'static,
2689    {
2690        self.window_cx.read_window(window, read)
2691    }
2692}
2693
2694impl<V: 'static> VisualContext for ViewContext<'_, V> {
2695    fn build_view<W: Render + 'static>(
2696        &mut self,
2697        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2698    ) -> Self::Result<View<W>> {
2699        self.window_cx.build_view(build_view_state)
2700    }
2701
2702    fn update_view<V2: 'static, R>(
2703        &mut self,
2704        view: &View<V2>,
2705        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2706    ) -> Self::Result<R> {
2707        self.window_cx.update_view(view, update)
2708    }
2709
2710    fn replace_root_view<W>(
2711        &mut self,
2712        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2713    ) -> Self::Result<View<W>>
2714    where
2715        W: 'static + Render,
2716    {
2717        self.window_cx.replace_root_view(build_view)
2718    }
2719
2720    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2721        self.window_cx.focus_view(view)
2722    }
2723
2724    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2725        self.window_cx.dismiss_view(view)
2726    }
2727}
2728
2729impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2730    type Target = WindowContext<'a>;
2731
2732    fn deref(&self) -> &Self::Target {
2733        &self.window_cx
2734    }
2735}
2736
2737impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2738    fn deref_mut(&mut self) -> &mut Self::Target {
2739        &mut self.window_cx
2740    }
2741}
2742
2743// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2744slotmap::new_key_type! { pub struct WindowId; }
2745
2746impl WindowId {
2747    pub fn as_u64(&self) -> u64 {
2748        self.0.as_ffi()
2749    }
2750}
2751
2752#[derive(Deref, DerefMut)]
2753pub struct WindowHandle<V> {
2754    #[deref]
2755    #[deref_mut]
2756    pub(crate) any_handle: AnyWindowHandle,
2757    state_type: PhantomData<V>,
2758}
2759
2760impl<V: 'static + Render> WindowHandle<V> {
2761    pub fn new(id: WindowId) -> Self {
2762        WindowHandle {
2763            any_handle: AnyWindowHandle {
2764                id,
2765                state_type: TypeId::of::<V>(),
2766            },
2767            state_type: PhantomData,
2768        }
2769    }
2770
2771    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2772    where
2773        C: Context,
2774    {
2775        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2776            root_view
2777                .downcast::<V>()
2778                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2779        }))
2780    }
2781
2782    pub fn update<C, R>(
2783        &self,
2784        cx: &mut C,
2785        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2786    ) -> Result<R>
2787    where
2788        C: Context,
2789    {
2790        cx.update_window(self.any_handle, |root_view, cx| {
2791            let view = root_view
2792                .downcast::<V>()
2793                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2794            Ok(cx.update_view(&view, update))
2795        })?
2796    }
2797
2798    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2799        let x = cx
2800            .windows
2801            .get(self.id)
2802            .and_then(|window| {
2803                window
2804                    .as_ref()
2805                    .and_then(|window| window.root_view.clone())
2806                    .map(|root_view| root_view.downcast::<V>())
2807            })
2808            .ok_or_else(|| anyhow!("window not found"))?
2809            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2810
2811        Ok(x.read(cx))
2812    }
2813
2814    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2815    where
2816        C: Context,
2817    {
2818        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2819    }
2820
2821    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2822    where
2823        C: Context,
2824    {
2825        cx.read_window(self, |root_view, _cx| root_view.clone())
2826    }
2827
2828    pub fn is_active(&self, cx: &AppContext) -> Option<bool> {
2829        cx.windows
2830            .get(self.id)
2831            .and_then(|window| window.as_ref().map(|window| window.active))
2832    }
2833}
2834
2835impl<V> Copy for WindowHandle<V> {}
2836
2837impl<V> Clone for WindowHandle<V> {
2838    fn clone(&self) -> Self {
2839        WindowHandle {
2840            any_handle: self.any_handle,
2841            state_type: PhantomData,
2842        }
2843    }
2844}
2845
2846impl<V> PartialEq for WindowHandle<V> {
2847    fn eq(&self, other: &Self) -> bool {
2848        self.any_handle == other.any_handle
2849    }
2850}
2851
2852impl<V> Eq for WindowHandle<V> {}
2853
2854impl<V> Hash for WindowHandle<V> {
2855    fn hash<H: Hasher>(&self, state: &mut H) {
2856        self.any_handle.hash(state);
2857    }
2858}
2859
2860impl<V: 'static> Into<AnyWindowHandle> for WindowHandle<V> {
2861    fn into(self) -> AnyWindowHandle {
2862        self.any_handle
2863    }
2864}
2865
2866#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2867pub struct AnyWindowHandle {
2868    pub(crate) id: WindowId,
2869    state_type: TypeId,
2870}
2871
2872impl AnyWindowHandle {
2873    pub fn window_id(&self) -> WindowId {
2874        self.id
2875    }
2876
2877    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2878        if TypeId::of::<T>() == self.state_type {
2879            Some(WindowHandle {
2880                any_handle: *self,
2881                state_type: PhantomData,
2882            })
2883        } else {
2884            None
2885        }
2886    }
2887
2888    pub fn update<C, R>(
2889        self,
2890        cx: &mut C,
2891        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2892    ) -> Result<R>
2893    where
2894        C: Context,
2895    {
2896        cx.update_window(self, update)
2897    }
2898
2899    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2900    where
2901        C: Context,
2902        T: 'static,
2903    {
2904        let view = self
2905            .downcast::<T>()
2906            .context("the type of the window's root view has changed")?;
2907
2908        cx.read_window(&view, read)
2909    }
2910}
2911
2912// #[cfg(any(test, feature = "test-support"))]
2913// impl From<SmallVec<[u32; 16]>> for StackingOrder {
2914//     fn from(small_vec: SmallVec<[u32; 16]>) -> Self {
2915//         StackingOrder(small_vec)
2916//     }
2917// }
2918
2919#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2920pub enum ElementId {
2921    View(EntityId),
2922    Integer(usize),
2923    Name(SharedString),
2924    FocusHandle(FocusId),
2925    NamedInteger(SharedString, usize),
2926}
2927
2928impl ElementId {
2929    pub(crate) fn from_entity_id(entity_id: EntityId) -> Self {
2930        ElementId::View(entity_id)
2931    }
2932}
2933
2934impl TryInto<SharedString> for ElementId {
2935    type Error = anyhow::Error;
2936
2937    fn try_into(self) -> anyhow::Result<SharedString> {
2938        if let ElementId::Name(name) = self {
2939            Ok(name)
2940        } else {
2941            Err(anyhow!("element id is not string"))
2942        }
2943    }
2944}
2945
2946impl From<usize> for ElementId {
2947    fn from(id: usize) -> Self {
2948        ElementId::Integer(id)
2949    }
2950}
2951
2952impl From<i32> for ElementId {
2953    fn from(id: i32) -> Self {
2954        Self::Integer(id as usize)
2955    }
2956}
2957
2958impl From<SharedString> for ElementId {
2959    fn from(name: SharedString) -> Self {
2960        ElementId::Name(name)
2961    }
2962}
2963
2964impl From<&'static str> for ElementId {
2965    fn from(name: &'static str) -> Self {
2966        ElementId::Name(name.into())
2967    }
2968}
2969
2970impl<'a> From<&'a FocusHandle> for ElementId {
2971    fn from(handle: &'a FocusHandle) -> Self {
2972        ElementId::FocusHandle(handle.id)
2973    }
2974}
2975
2976impl From<(&'static str, EntityId)> for ElementId {
2977    fn from((name, id): (&'static str, EntityId)) -> Self {
2978        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2979    }
2980}
2981
2982impl From<(&'static str, usize)> for ElementId {
2983    fn from((name, id): (&'static str, usize)) -> Self {
2984        ElementId::NamedInteger(name.into(), id)
2985    }
2986}
2987
2988impl From<(&'static str, u64)> for ElementId {
2989    fn from((name, id): (&'static str, u64)) -> Self {
2990        ElementId::NamedInteger(name.into(), id as usize)
2991    }
2992}
2993
2994/// A rectangle, to be rendered on the screen by GPUI at the given position and size.
2995pub struct PaintQuad {
2996    bounds: Bounds<Pixels>,
2997    corner_radii: Corners<Pixels>,
2998    background: Hsla,
2999    border_widths: Edges<Pixels>,
3000    border_color: Hsla,
3001}
3002
3003impl PaintQuad {
3004    /// Set the corner radii of the quad.
3005    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
3006        PaintQuad {
3007            corner_radii: corner_radii.into(),
3008            ..self
3009        }
3010    }
3011
3012    /// Set the border widths of the quad.
3013    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
3014        PaintQuad {
3015            border_widths: border_widths.into(),
3016            ..self
3017        }
3018    }
3019
3020    /// Set the border color of the quad.
3021    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
3022        PaintQuad {
3023            border_color: border_color.into(),
3024            ..self
3025        }
3026    }
3027
3028    /// Set the background color of the quad.
3029    pub fn background(self, background: impl Into<Hsla>) -> Self {
3030        PaintQuad {
3031            background: background.into(),
3032            ..self
3033        }
3034    }
3035}
3036
3037/// Create a quad with the given parameters.
3038pub fn quad(
3039    bounds: Bounds<Pixels>,
3040    corner_radii: impl Into<Corners<Pixels>>,
3041    background: impl Into<Hsla>,
3042    border_widths: impl Into<Edges<Pixels>>,
3043    border_color: impl Into<Hsla>,
3044) -> PaintQuad {
3045    PaintQuad {
3046        bounds,
3047        corner_radii: corner_radii.into(),
3048        background: background.into(),
3049        border_widths: border_widths.into(),
3050        border_color: border_color.into(),
3051    }
3052}
3053
3054/// Create a filled quad with the given bounds and background color.
3055pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
3056    PaintQuad {
3057        bounds: bounds.into(),
3058        corner_radii: (0.).into(),
3059        background: background.into(),
3060        border_widths: (0.).into(),
3061        border_color: transparent_black(),
3062    }
3063}
3064
3065/// Create a rectangle outline with the given bounds, border color, and a 1px border width
3066pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
3067    PaintQuad {
3068        bounds: bounds.into(),
3069        corner_radii: (0.).into(),
3070        background: transparent_black(),
3071        border_widths: (1.).into(),
3072        border_color: border_color.into(),
3073    }
3074}