window.rs

   1use crate::{
   2    point, px, size, transparent_black, Action, AnyDrag, AnyView, AppContext, Arena,
   3    AsyncWindowContext, Bounds, Context, Corners, CursorStyle, DevicePixels,
   4    DispatchActionListener, DispatchNodeId, DispatchTree, DisplayId, Edges, Effect, Entity,
   5    EntityId, EventEmitter, FileDropEvent, Flatten, Global, GlobalElementId, Hsla, KeyBinding,
   6    KeyDownEvent, KeyMatch, KeymatchResult, Keystroke, KeystrokeEvent, Model, ModelContext,
   7    Modifiers, ModifiersChangedEvent, MouseButton, MouseMoveEvent, MouseUpEvent, Pixels,
   8    PlatformAtlas, PlatformDisplay, PlatformInput, PlatformWindow, Point, PromptLevel, Render,
   9    ScaledPixels, SharedString, Size, SubscriberSet, Subscription, TaffyLayoutEngine, Task,
  10    TextStyle, TextStyleRefinement, View, VisualContext, WeakView, WindowAppearance,
  11    WindowBackgroundAppearance, WindowOptions, WindowParams, WindowTextSystem,
  12};
  13use anyhow::{anyhow, Context as _, Result};
  14use collections::FxHashSet;
  15use derive_more::{Deref, DerefMut};
  16use futures::channel::oneshot;
  17use parking_lot::RwLock;
  18use refineable::Refineable;
  19use slotmap::SlotMap;
  20use smallvec::SmallVec;
  21use std::{
  22    any::{Any, TypeId},
  23    borrow::{Borrow, BorrowMut},
  24    cell::{Cell, RefCell},
  25    fmt::{Debug, Display},
  26    future::Future,
  27    hash::{Hash, Hasher},
  28    marker::PhantomData,
  29    mem,
  30    rc::Rc,
  31    sync::{
  32        atomic::{AtomicUsize, Ordering::SeqCst},
  33        Arc, Weak,
  34    },
  35    time::{Duration, Instant},
  36};
  37use util::{measure, ResultExt};
  38
  39mod element_cx;
  40mod prompts;
  41
  42pub use element_cx::*;
  43pub use prompts::*;
  44
  45/// Represents the two different phases when dispatching events.
  46#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  47pub enum DispatchPhase {
  48    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  49    /// invoked front to back and keyboard event listeners are invoked from the focused element
  50    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  51    /// registering event listeners.
  52    #[default]
  53    Bubble,
  54    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  55    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  56    /// is used for special purposes such as clearing the "pressed" state for click events. If
  57    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  58    /// outside of the immediate region may rely on detecting non-local events during this phase.
  59    Capture,
  60}
  61
  62impl DispatchPhase {
  63    /// Returns true if this represents the "bubble" phase.
  64    pub fn bubble(self) -> bool {
  65        self == DispatchPhase::Bubble
  66    }
  67
  68    /// Returns true if this represents the "capture" phase.
  69    pub fn capture(self) -> bool {
  70        self == DispatchPhase::Capture
  71    }
  72}
  73
  74type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
  75
  76type AnyWindowFocusListener = Box<dyn FnMut(&FocusEvent, &mut WindowContext) -> bool + 'static>;
  77
  78struct FocusEvent {
  79    previous_focus_path: SmallVec<[FocusId; 8]>,
  80    current_focus_path: SmallVec<[FocusId; 8]>,
  81}
  82
  83slotmap::new_key_type! {
  84    /// A globally unique identifier for a focusable element.
  85    pub struct FocusId;
  86}
  87
  88thread_local! {
  89    pub(crate) static ELEMENT_ARENA: RefCell<Arena> = RefCell::new(Arena::new(8 * 1024 * 1024));
  90}
  91
  92impl FocusId {
  93    /// Obtains whether the element associated with this handle is currently focused.
  94    pub fn is_focused(&self, cx: &WindowContext) -> bool {
  95        cx.window.focus == Some(*self)
  96    }
  97
  98    /// Obtains whether the element associated with this handle contains the focused
  99    /// element or is itself focused.
 100    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 101        cx.focused()
 102            .map_or(false, |focused| self.contains(focused.id, cx))
 103    }
 104
 105    /// Obtains whether the element associated with this handle is contained within the
 106    /// focused element or is itself focused.
 107    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 108        let focused = cx.focused();
 109        focused.map_or(false, |focused| focused.id.contains(*self, cx))
 110    }
 111
 112    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 113    pub(crate) fn contains(&self, other: Self, cx: &WindowContext) -> bool {
 114        cx.window
 115            .rendered_frame
 116            .dispatch_tree
 117            .focus_contains(*self, other)
 118    }
 119}
 120
 121/// A handle which can be used to track and manipulate the focused element in a window.
 122pub struct FocusHandle {
 123    pub(crate) id: FocusId,
 124    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 125}
 126
 127impl std::fmt::Debug for FocusHandle {
 128    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 129        f.write_fmt(format_args!("FocusHandle({:?})", self.id))
 130    }
 131}
 132
 133impl FocusHandle {
 134    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
 135        let id = handles.write().insert(AtomicUsize::new(1));
 136        Self {
 137            id,
 138            handles: handles.clone(),
 139        }
 140    }
 141
 142    pub(crate) fn for_id(
 143        id: FocusId,
 144        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 145    ) -> Option<Self> {
 146        let lock = handles.read();
 147        let ref_count = lock.get(id)?;
 148        if ref_count.load(SeqCst) == 0 {
 149            None
 150        } else {
 151            ref_count.fetch_add(1, SeqCst);
 152            Some(Self {
 153                id,
 154                handles: handles.clone(),
 155            })
 156        }
 157    }
 158
 159    /// Converts this focus handle into a weak variant, which does not prevent it from being released.
 160    pub fn downgrade(&self) -> WeakFocusHandle {
 161        WeakFocusHandle {
 162            id: self.id,
 163            handles: Arc::downgrade(&self.handles),
 164        }
 165    }
 166
 167    /// Moves the focus to the element associated with this handle.
 168    pub fn focus(&self, cx: &mut WindowContext) {
 169        cx.focus(self)
 170    }
 171
 172    /// Obtains whether the element associated with this handle is currently focused.
 173    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 174        self.id.is_focused(cx)
 175    }
 176
 177    /// Obtains whether the element associated with this handle contains the focused
 178    /// element or is itself focused.
 179    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 180        self.id.contains_focused(cx)
 181    }
 182
 183    /// Obtains whether the element associated with this handle is contained within the
 184    /// focused element or is itself focused.
 185    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 186        self.id.within_focused(cx)
 187    }
 188
 189    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 190    pub fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 191        self.id.contains(other.id, cx)
 192    }
 193}
 194
 195impl Clone for FocusHandle {
 196    fn clone(&self) -> Self {
 197        Self::for_id(self.id, &self.handles).unwrap()
 198    }
 199}
 200
 201impl PartialEq for FocusHandle {
 202    fn eq(&self, other: &Self) -> bool {
 203        self.id == other.id
 204    }
 205}
 206
 207impl Eq for FocusHandle {}
 208
 209impl Drop for FocusHandle {
 210    fn drop(&mut self) {
 211        self.handles
 212            .read()
 213            .get(self.id)
 214            .unwrap()
 215            .fetch_sub(1, SeqCst);
 216    }
 217}
 218
 219/// A weak reference to a focus handle.
 220#[derive(Clone, Debug)]
 221pub struct WeakFocusHandle {
 222    pub(crate) id: FocusId,
 223    handles: Weak<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 224}
 225
 226impl WeakFocusHandle {
 227    /// Attempts to upgrade the [WeakFocusHandle] to a [FocusHandle].
 228    pub fn upgrade(&self) -> Option<FocusHandle> {
 229        let handles = self.handles.upgrade()?;
 230        FocusHandle::for_id(self.id, &handles)
 231    }
 232}
 233
 234impl PartialEq for WeakFocusHandle {
 235    fn eq(&self, other: &WeakFocusHandle) -> bool {
 236        self.id == other.id
 237    }
 238}
 239
 240impl Eq for WeakFocusHandle {}
 241
 242impl PartialEq<FocusHandle> for WeakFocusHandle {
 243    fn eq(&self, other: &FocusHandle) -> bool {
 244        self.id == other.id
 245    }
 246}
 247
 248impl PartialEq<WeakFocusHandle> for FocusHandle {
 249    fn eq(&self, other: &WeakFocusHandle) -> bool {
 250        self.id == other.id
 251    }
 252}
 253
 254/// FocusableView allows users of your view to easily
 255/// focus it (using cx.focus_view(view))
 256pub trait FocusableView: 'static + Render {
 257    /// Returns the focus handle associated with this view.
 258    fn focus_handle(&self, cx: &AppContext) -> FocusHandle;
 259}
 260
 261/// ManagedView is a view (like a Modal, Popover, Menu, etc.)
 262/// where the lifecycle of the view is handled by another view.
 263pub trait ManagedView: FocusableView + EventEmitter<DismissEvent> {}
 264
 265impl<M: FocusableView + EventEmitter<DismissEvent>> ManagedView for M {}
 266
 267/// Emitted by implementers of [`ManagedView`] to indicate the view should be dismissed, such as when a view is presented as a modal.
 268pub struct DismissEvent;
 269
 270type FrameCallback = Box<dyn FnOnce(&mut WindowContext)>;
 271
 272// Holds the state for a specific window.
 273#[doc(hidden)]
 274pub struct Window {
 275    pub(crate) handle: AnyWindowHandle,
 276    pub(crate) removed: bool,
 277    pub(crate) platform_window: Box<dyn PlatformWindow>,
 278    display_id: DisplayId,
 279    sprite_atlas: Arc<dyn PlatformAtlas>,
 280    text_system: Arc<WindowTextSystem>,
 281    pub(crate) rem_size: Pixels,
 282    pub(crate) viewport_size: Size<Pixels>,
 283    layout_engine: Option<TaffyLayoutEngine>,
 284    pub(crate) root_view: Option<AnyView>,
 285    pub(crate) element_id_stack: GlobalElementId,
 286    pub(crate) text_style_stack: Vec<TextStyleRefinement>,
 287    pub(crate) rendered_frame: Frame,
 288    pub(crate) next_frame: Frame,
 289    pub(crate) next_hitbox_id: HitboxId,
 290    next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>>,
 291    pub(crate) dirty_views: FxHashSet<EntityId>,
 292    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 293    focus_listeners: SubscriberSet<(), AnyWindowFocusListener>,
 294    focus_lost_listeners: SubscriberSet<(), AnyObserver>,
 295    default_prevented: bool,
 296    mouse_position: Point<Pixels>,
 297    mouse_hit_test: HitTest,
 298    modifiers: Modifiers,
 299    scale_factor: f32,
 300    bounds_observers: SubscriberSet<(), AnyObserver>,
 301    appearance: WindowAppearance,
 302    appearance_observers: SubscriberSet<(), AnyObserver>,
 303    active: Rc<Cell<bool>>,
 304    pub(crate) dirty: Rc<Cell<bool>>,
 305    pub(crate) needs_present: Rc<Cell<bool>>,
 306    pub(crate) last_input_timestamp: Rc<Cell<Instant>>,
 307    pub(crate) refreshing: bool,
 308    pub(crate) draw_phase: DrawPhase,
 309    activation_observers: SubscriberSet<(), AnyObserver>,
 310    pub(crate) focus: Option<FocusId>,
 311    focus_enabled: bool,
 312    pending_input: Option<PendingInput>,
 313    prompt: Option<RenderablePromptHandle>,
 314}
 315
 316#[derive(Clone, Copy, Debug, Eq, PartialEq)]
 317pub(crate) enum DrawPhase {
 318    None,
 319    Layout,
 320    Paint,
 321    Focus,
 322}
 323
 324#[derive(Default, Debug)]
 325struct PendingInput {
 326    keystrokes: SmallVec<[Keystroke; 1]>,
 327    bindings: SmallVec<[KeyBinding; 1]>,
 328    focus: Option<FocusId>,
 329    timer: Option<Task<()>>,
 330}
 331
 332impl PendingInput {
 333    fn input(&self) -> String {
 334        self.keystrokes
 335            .iter()
 336            .flat_map(|k| k.ime_key.clone())
 337            .collect::<Vec<String>>()
 338            .join("")
 339    }
 340
 341    fn used_by_binding(&self, binding: &KeyBinding) -> bool {
 342        if self.keystrokes.is_empty() {
 343            return true;
 344        }
 345        let keystroke = &self.keystrokes[0];
 346        for candidate in keystroke.match_candidates() {
 347            if binding.match_keystrokes(&[candidate]) == KeyMatch::Pending {
 348                return true;
 349            }
 350        }
 351        false
 352    }
 353}
 354
 355pub(crate) struct ElementStateBox {
 356    pub(crate) inner: Box<dyn Any>,
 357    #[cfg(debug_assertions)]
 358    pub(crate) type_name: &'static str,
 359}
 360
 361fn default_bounds(display_id: Option<DisplayId>, cx: &mut AppContext) -> Bounds<DevicePixels> {
 362    const DEFAULT_WINDOW_SIZE: Size<DevicePixels> = size(DevicePixels(1024), DevicePixels(700));
 363    const DEFAULT_WINDOW_OFFSET: Point<DevicePixels> = point(DevicePixels(0), DevicePixels(35));
 364
 365    cx.active_window()
 366        .and_then(|w| w.update(cx, |_, cx| cx.window_bounds()).ok())
 367        .map(|bounds| bounds.map_origin(|origin| origin + DEFAULT_WINDOW_OFFSET))
 368        .unwrap_or_else(|| {
 369            let display = display_id
 370                .map(|id| cx.find_display(id))
 371                .unwrap_or_else(|| cx.primary_display());
 372
 373            display
 374                .map(|display| {
 375                    let center = display.bounds().center();
 376                    let offset = DEFAULT_WINDOW_SIZE / 2;
 377                    let origin = point(center.x - offset.width, center.y - offset.height);
 378                    Bounds::new(origin, DEFAULT_WINDOW_SIZE)
 379                })
 380                .unwrap_or_else(|| {
 381                    Bounds::new(point(DevicePixels(0), DevicePixels(0)), DEFAULT_WINDOW_SIZE)
 382                })
 383        })
 384}
 385
 386impl Window {
 387    pub(crate) fn new(
 388        handle: AnyWindowHandle,
 389        options: WindowOptions,
 390        cx: &mut AppContext,
 391    ) -> Self {
 392        let WindowOptions {
 393            bounds,
 394            titlebar,
 395            focus,
 396            show,
 397            kind,
 398            is_movable,
 399            display_id,
 400            fullscreen,
 401            window_background,
 402        } = options;
 403
 404        let bounds = bounds.unwrap_or_else(|| default_bounds(display_id, cx));
 405        let platform_window = cx.platform.open_window(
 406            handle,
 407            WindowParams {
 408                bounds,
 409                titlebar,
 410                kind,
 411                is_movable,
 412                focus,
 413                show,
 414                display_id,
 415                window_background,
 416            },
 417        );
 418        let display_id = platform_window.display().id();
 419        let sprite_atlas = platform_window.sprite_atlas();
 420        let mouse_position = platform_window.mouse_position();
 421        let modifiers = platform_window.modifiers();
 422        let content_size = platform_window.content_size();
 423        let scale_factor = platform_window.scale_factor();
 424        let appearance = platform_window.appearance();
 425        let text_system = Arc::new(WindowTextSystem::new(cx.text_system().clone()));
 426        let dirty = Rc::new(Cell::new(true));
 427        let active = Rc::new(Cell::new(platform_window.is_active()));
 428        let needs_present = Rc::new(Cell::new(false));
 429        let next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>> = Default::default();
 430        let last_input_timestamp = Rc::new(Cell::new(Instant::now()));
 431
 432        if fullscreen {
 433            platform_window.toggle_fullscreen();
 434        }
 435
 436        platform_window.on_close(Box::new({
 437            let mut cx = cx.to_async();
 438            move || {
 439                let _ = handle.update(&mut cx, |_, cx| cx.remove_window());
 440            }
 441        }));
 442        platform_window.on_request_frame(Box::new({
 443            let mut cx = cx.to_async();
 444            let dirty = dirty.clone();
 445            let active = active.clone();
 446            let needs_present = needs_present.clone();
 447            let next_frame_callbacks = next_frame_callbacks.clone();
 448            let last_input_timestamp = last_input_timestamp.clone();
 449            move || {
 450                let next_frame_callbacks = next_frame_callbacks.take();
 451                if !next_frame_callbacks.is_empty() {
 452                    handle
 453                        .update(&mut cx, |_, cx| {
 454                            for callback in next_frame_callbacks {
 455                                callback(cx);
 456                            }
 457                        })
 458                        .log_err();
 459                }
 460
 461                // Keep presenting the current scene for 1 extra second since the
 462                // last input to prevent the display from underclocking the refresh rate.
 463                let needs_present = needs_present.get()
 464                    || (active.get()
 465                        && last_input_timestamp.get().elapsed() < Duration::from_secs(1));
 466
 467                if dirty.get() {
 468                    measure("frame duration", || {
 469                        handle
 470                            .update(&mut cx, |_, cx| {
 471                                cx.draw();
 472                                cx.present();
 473                            })
 474                            .log_err();
 475                    })
 476                } else if needs_present {
 477                    handle.update(&mut cx, |_, cx| cx.present()).log_err();
 478                }
 479
 480                handle
 481                    .update(&mut cx, |_, cx| {
 482                        cx.complete_frame();
 483                    })
 484                    .log_err();
 485            }
 486        }));
 487        platform_window.on_resize(Box::new({
 488            let mut cx = cx.to_async();
 489            move |_, _| {
 490                handle
 491                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 492                    .log_err();
 493            }
 494        }));
 495        platform_window.on_moved(Box::new({
 496            let mut cx = cx.to_async();
 497            move || {
 498                handle
 499                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 500                    .log_err();
 501            }
 502        }));
 503        platform_window.on_appearance_changed(Box::new({
 504            let mut cx = cx.to_async();
 505            move || {
 506                handle
 507                    .update(&mut cx, |_, cx| cx.appearance_changed())
 508                    .log_err();
 509            }
 510        }));
 511        platform_window.on_active_status_change(Box::new({
 512            let mut cx = cx.to_async();
 513            move |active| {
 514                handle
 515                    .update(&mut cx, |_, cx| {
 516                        cx.window.active.set(active);
 517                        cx.window
 518                            .activation_observers
 519                            .clone()
 520                            .retain(&(), |callback| callback(cx));
 521                        cx.refresh();
 522                    })
 523                    .log_err();
 524            }
 525        }));
 526
 527        platform_window.on_input({
 528            let mut cx = cx.to_async();
 529            Box::new(move |event| {
 530                handle
 531                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 532                    .log_err()
 533                    .unwrap_or(DispatchEventResult::default())
 534            })
 535        });
 536
 537        Window {
 538            handle,
 539            removed: false,
 540            platform_window,
 541            display_id,
 542            sprite_atlas,
 543            text_system,
 544            rem_size: px(16.),
 545            viewport_size: content_size,
 546            layout_engine: Some(TaffyLayoutEngine::new()),
 547            root_view: None,
 548            element_id_stack: GlobalElementId::default(),
 549            text_style_stack: Vec::new(),
 550            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 551            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 552            next_frame_callbacks,
 553            next_hitbox_id: HitboxId::default(),
 554            dirty_views: FxHashSet::default(),
 555            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 556            focus_listeners: SubscriberSet::new(),
 557            focus_lost_listeners: SubscriberSet::new(),
 558            default_prevented: true,
 559            mouse_position,
 560            mouse_hit_test: HitTest::default(),
 561            modifiers,
 562            scale_factor,
 563            bounds_observers: SubscriberSet::new(),
 564            appearance,
 565            appearance_observers: SubscriberSet::new(),
 566            active,
 567            dirty,
 568            needs_present,
 569            last_input_timestamp,
 570            refreshing: false,
 571            draw_phase: DrawPhase::None,
 572            activation_observers: SubscriberSet::new(),
 573            focus: None,
 574            focus_enabled: true,
 575            pending_input: None,
 576            prompt: None,
 577        }
 578    }
 579    fn new_focus_listener(
 580        &mut self,
 581        value: AnyWindowFocusListener,
 582    ) -> (Subscription, impl FnOnce()) {
 583        self.focus_listeners.insert((), value)
 584    }
 585}
 586
 587#[derive(Clone, Debug, Default, PartialEq, Eq)]
 588pub(crate) struct DispatchEventResult {
 589    pub propagate: bool,
 590    pub default_prevented: bool,
 591}
 592
 593/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 594/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 595/// to leave room to support more complex shapes in the future.
 596#[derive(Clone, Debug, Default, PartialEq, Eq)]
 597#[repr(C)]
 598pub struct ContentMask<P: Clone + Default + Debug> {
 599    /// The bounds
 600    pub bounds: Bounds<P>,
 601}
 602
 603impl ContentMask<Pixels> {
 604    /// Scale the content mask's pixel units by the given scaling factor.
 605    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 606        ContentMask {
 607            bounds: self.bounds.scale(factor),
 608        }
 609    }
 610
 611    /// Intersect the content mask with the given content mask.
 612    pub fn intersect(&self, other: &Self) -> Self {
 613        let bounds = self.bounds.intersect(&other.bounds);
 614        ContentMask { bounds }
 615    }
 616}
 617
 618/// Provides access to application state in the context of a single window. Derefs
 619/// to an [`AppContext`], so you can also pass a [`WindowContext`] to any method that takes
 620/// an [`AppContext`] and call any [`AppContext`] methods.
 621pub struct WindowContext<'a> {
 622    pub(crate) app: &'a mut AppContext,
 623    pub(crate) window: &'a mut Window,
 624}
 625
 626impl<'a> WindowContext<'a> {
 627    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 628        Self { app, window }
 629    }
 630
 631    /// Obtain a handle to the window that belongs to this context.
 632    pub fn window_handle(&self) -> AnyWindowHandle {
 633        self.window.handle
 634    }
 635
 636    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 637    pub fn refresh(&mut self) {
 638        if self.window.draw_phase == DrawPhase::None {
 639            self.window.refreshing = true;
 640            self.window.dirty.set(true);
 641        }
 642    }
 643
 644    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
 645    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
 646    pub fn notify(&mut self, view_id: EntityId) {
 647        for view_id in self
 648            .window
 649            .rendered_frame
 650            .dispatch_tree
 651            .view_path(view_id)
 652            .into_iter()
 653            .rev()
 654        {
 655            if !self.window.dirty_views.insert(view_id) {
 656                break;
 657            }
 658        }
 659
 660        if self.window.draw_phase == DrawPhase::None {
 661            self.window.dirty.set(true);
 662            self.app.push_effect(Effect::Notify { emitter: view_id });
 663        }
 664    }
 665
 666    /// Close this window.
 667    pub fn remove_window(&mut self) {
 668        self.window.removed = true;
 669    }
 670
 671    /// Obtain a new [`FocusHandle`], which allows you to track and manipulate the keyboard focus
 672    /// for elements rendered within this window.
 673    pub fn focus_handle(&mut self) -> FocusHandle {
 674        FocusHandle::new(&self.window.focus_handles)
 675    }
 676
 677    /// Obtain the currently focused [`FocusHandle`]. If no elements are focused, returns `None`.
 678    pub fn focused(&self) -> Option<FocusHandle> {
 679        self.window
 680            .focus
 681            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 682    }
 683
 684    /// Move focus to the element associated with the given [`FocusHandle`].
 685    pub fn focus(&mut self, handle: &FocusHandle) {
 686        if !self.window.focus_enabled || self.window.focus == Some(handle.id) {
 687            return;
 688        }
 689
 690        self.window.focus = Some(handle.id);
 691        self.window
 692            .rendered_frame
 693            .dispatch_tree
 694            .clear_pending_keystrokes();
 695        self.refresh();
 696    }
 697
 698    /// Remove focus from all elements within this context's window.
 699    pub fn blur(&mut self) {
 700        if !self.window.focus_enabled {
 701            return;
 702        }
 703
 704        self.window.focus = None;
 705        self.refresh();
 706    }
 707
 708    /// Blur the window and don't allow anything in it to be focused again.
 709    pub fn disable_focus(&mut self) {
 710        self.blur();
 711        self.window.focus_enabled = false;
 712    }
 713
 714    /// Accessor for the text system.
 715    pub fn text_system(&self) -> &Arc<WindowTextSystem> {
 716        &self.window.text_system
 717    }
 718
 719    /// The current text style. Which is composed of all the style refinements provided to `with_text_style`.
 720    pub fn text_style(&self) -> TextStyle {
 721        let mut style = TextStyle::default();
 722        for refinement in &self.window.text_style_stack {
 723            style.refine(refinement);
 724        }
 725        style
 726    }
 727
 728    /// Check if the platform window is maximized
 729    /// On some platforms (namely Windows) this is different than the bounds being the size of the display
 730    pub fn is_maximized(&self) -> bool {
 731        self.window.platform_window.is_maximized()
 732    }
 733
 734    /// Check if the platform window is minimized
 735    /// On some platforms (namely Windows) the position is incorrect when minimized
 736    pub fn is_minimized(&self) -> bool {
 737        self.window.platform_window.is_minimized()
 738    }
 739
 740    /// Dispatch the given action on the currently focused element.
 741    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 742        let focus_handle = self.focused();
 743
 744        let window = self.window.handle;
 745        self.app.defer(move |cx| {
 746            window
 747                .update(cx, |_, cx| {
 748                    let node_id = focus_handle
 749                        .and_then(|handle| {
 750                            cx.window
 751                                .rendered_frame
 752                                .dispatch_tree
 753                                .focusable_node_id(handle.id)
 754                        })
 755                        .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 756
 757                    cx.dispatch_action_on_node(node_id, action.as_ref());
 758                })
 759                .log_err();
 760        })
 761    }
 762
 763    pub(crate) fn dispatch_keystroke_observers(
 764        &mut self,
 765        event: &dyn Any,
 766        action: Option<Box<dyn Action>>,
 767    ) {
 768        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 769            return;
 770        };
 771
 772        self.keystroke_observers
 773            .clone()
 774            .retain(&(), move |callback| {
 775                (callback)(
 776                    &KeystrokeEvent {
 777                        keystroke: key_down_event.keystroke.clone(),
 778                        action: action.as_ref().map(|action| action.boxed_clone()),
 779                    },
 780                    self,
 781                );
 782                true
 783            });
 784    }
 785
 786    pub(crate) fn clear_pending_keystrokes(&mut self) {
 787        self.window
 788            .rendered_frame
 789            .dispatch_tree
 790            .clear_pending_keystrokes();
 791        self.window
 792            .next_frame
 793            .dispatch_tree
 794            .clear_pending_keystrokes();
 795    }
 796
 797    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 798    /// that are currently on the stack to be returned to the app.
 799    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 800        let handle = self.window.handle;
 801        self.app.defer(move |cx| {
 802            handle.update(cx, |_, cx| f(cx)).ok();
 803        });
 804    }
 805
 806    /// Subscribe to events emitted by a model or view.
 807    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
 808    /// The callback will be invoked a handle to the emitting entity (either a [`View`] or [`Model`]), the event, and a window context for the current window.
 809    pub fn subscribe<Emitter, E, Evt>(
 810        &mut self,
 811        entity: &E,
 812        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 813    ) -> Subscription
 814    where
 815        Emitter: EventEmitter<Evt>,
 816        E: Entity<Emitter>,
 817        Evt: 'static,
 818    {
 819        let entity_id = entity.entity_id();
 820        let entity = entity.downgrade();
 821        let window_handle = self.window.handle;
 822        self.app.new_subscription(
 823            entity_id,
 824            (
 825                TypeId::of::<Evt>(),
 826                Box::new(move |event, cx| {
 827                    window_handle
 828                        .update(cx, |_, cx| {
 829                            if let Some(handle) = E::upgrade_from(&entity) {
 830                                let event = event.downcast_ref().expect("invalid event type");
 831                                on_event(handle, event, cx);
 832                                true
 833                            } else {
 834                                false
 835                            }
 836                        })
 837                        .unwrap_or(false)
 838                }),
 839            ),
 840        )
 841    }
 842
 843    /// Creates an [`AsyncWindowContext`], which has a static lifetime and can be held across
 844    /// await points in async code.
 845    pub fn to_async(&self) -> AsyncWindowContext {
 846        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 847    }
 848
 849    /// Schedule the given closure to be run directly after the current frame is rendered.
 850    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 851        RefCell::borrow_mut(&self.window.next_frame_callbacks).push(Box::new(callback));
 852    }
 853
 854    /// Spawn the future returned by the given closure on the application thread pool.
 855    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 856    /// use within your future.
 857    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 858    where
 859        R: 'static,
 860        Fut: Future<Output = R> + 'static,
 861    {
 862        self.app
 863            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 864    }
 865
 866    fn window_bounds_changed(&mut self) {
 867        self.window.scale_factor = self.window.platform_window.scale_factor();
 868        self.window.viewport_size = self.window.platform_window.content_size();
 869        self.window.display_id = self.window.platform_window.display().id();
 870        self.refresh();
 871
 872        self.window
 873            .bounds_observers
 874            .clone()
 875            .retain(&(), |callback| callback(self));
 876    }
 877
 878    /// Returns the bounds of the current window in the global coordinate space, which could span across multiple displays.
 879    pub fn window_bounds(&self) -> Bounds<DevicePixels> {
 880        self.window.platform_window.bounds()
 881    }
 882
 883    /// Returns whether or not the window is currently fullscreen
 884    pub fn is_fullscreen(&self) -> bool {
 885        self.window.platform_window.is_fullscreen()
 886    }
 887
 888    fn appearance_changed(&mut self) {
 889        self.window.appearance = self.window.platform_window.appearance();
 890
 891        self.window
 892            .appearance_observers
 893            .clone()
 894            .retain(&(), |callback| callback(self));
 895    }
 896
 897    /// Returns the appearance of the current window.
 898    pub fn appearance(&self) -> WindowAppearance {
 899        self.window.appearance
 900    }
 901
 902    /// Returns the size of the drawable area within the window.
 903    pub fn viewport_size(&self) -> Size<Pixels> {
 904        self.window.viewport_size
 905    }
 906
 907    /// Returns whether this window is focused by the operating system (receiving key events).
 908    pub fn is_window_active(&self) -> bool {
 909        self.window.active.get()
 910    }
 911
 912    /// Toggle zoom on the window.
 913    pub fn zoom_window(&self) {
 914        self.window.platform_window.zoom();
 915    }
 916
 917    /// Updates the window's title at the platform level.
 918    pub fn set_window_title(&mut self, title: &str) {
 919        self.window.platform_window.set_title(title);
 920    }
 921
 922    /// Sets the window background appearance.
 923    pub fn set_background_appearance(&mut self, background_appearance: WindowBackgroundAppearance) {
 924        self.window
 925            .platform_window
 926            .set_background_appearance(background_appearance);
 927    }
 928
 929    /// Mark the window as dirty at the platform level.
 930    pub fn set_window_edited(&mut self, edited: bool) {
 931        self.window.platform_window.set_edited(edited);
 932    }
 933
 934    /// Determine the display on which the window is visible.
 935    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 936        self.platform
 937            .displays()
 938            .into_iter()
 939            .find(|display| display.id() == self.window.display_id)
 940    }
 941
 942    /// Show the platform character palette.
 943    pub fn show_character_palette(&self) {
 944        self.window.platform_window.show_character_palette();
 945    }
 946
 947    /// The scale factor of the display associated with the window. For example, it could
 948    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 949    /// be rendered as two pixels on screen.
 950    pub fn scale_factor(&self) -> f32 {
 951        self.window.scale_factor
 952    }
 953
 954    /// The size of an em for the base font of the application. Adjusting this value allows the
 955    /// UI to scale, just like zooming a web page.
 956    pub fn rem_size(&self) -> Pixels {
 957        self.window.rem_size
 958    }
 959
 960    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 961    /// UI to scale, just like zooming a web page.
 962    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 963        self.window.rem_size = rem_size.into();
 964    }
 965
 966    /// The line height associated with the current text style.
 967    pub fn line_height(&self) -> Pixels {
 968        let rem_size = self.rem_size();
 969        let text_style = self.text_style();
 970        text_style
 971            .line_height
 972            .to_pixels(text_style.font_size, rem_size)
 973    }
 974
 975    /// Call to prevent the default action of an event. Currently only used to prevent
 976    /// parent elements from becoming focused on mouse down.
 977    pub fn prevent_default(&mut self) {
 978        self.window.default_prevented = true;
 979    }
 980
 981    /// Obtain whether default has been prevented for the event currently being dispatched.
 982    pub fn default_prevented(&self) -> bool {
 983        self.window.default_prevented
 984    }
 985
 986    /// Determine whether the given action is available along the dispatch path to the currently focused element.
 987    pub fn is_action_available(&self, action: &dyn Action) -> bool {
 988        let target = self
 989            .focused()
 990            .and_then(|focused_handle| {
 991                self.window
 992                    .rendered_frame
 993                    .dispatch_tree
 994                    .focusable_node_id(focused_handle.id)
 995            })
 996            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
 997        self.window
 998            .rendered_frame
 999            .dispatch_tree
1000            .is_action_available(action, target)
1001    }
1002
1003    /// The position of the mouse relative to the window.
1004    pub fn mouse_position(&self) -> Point<Pixels> {
1005        self.window.mouse_position
1006    }
1007
1008    /// The current state of the keyboard's modifiers
1009    pub fn modifiers(&self) -> Modifiers {
1010        self.window.modifiers
1011    }
1012
1013    fn complete_frame(&self) {
1014        self.window.platform_window.completed_frame();
1015    }
1016
1017    /// Produces a new frame and assigns it to `rendered_frame`. To actually show
1018    /// the contents of the new [Scene], use [present].
1019    #[profiling::function]
1020    pub fn draw(&mut self) {
1021        self.window.dirty.set(false);
1022
1023        // Restore the previously-used input handler.
1024        if let Some(input_handler) = self.window.platform_window.take_input_handler() {
1025            self.window
1026                .rendered_frame
1027                .input_handlers
1028                .push(Some(input_handler));
1029        }
1030
1031        self.with_element_context(|cx| cx.draw_roots());
1032        self.window.dirty_views.clear();
1033
1034        self.window
1035            .next_frame
1036            .dispatch_tree
1037            .preserve_pending_keystrokes(
1038                &mut self.window.rendered_frame.dispatch_tree,
1039                self.window.focus,
1040            );
1041        self.window.next_frame.focus = self.window.focus;
1042        self.window.next_frame.window_active = self.window.active.get();
1043
1044        // Register requested input handler with the platform window.
1045        if let Some(input_handler) = self.window.next_frame.input_handlers.pop() {
1046            self.window
1047                .platform_window
1048                .set_input_handler(input_handler.unwrap());
1049        }
1050
1051        self.window.layout_engine.as_mut().unwrap().clear();
1052        self.text_system().finish_frame();
1053        self.window
1054            .next_frame
1055            .finish(&mut self.window.rendered_frame);
1056        ELEMENT_ARENA.with_borrow_mut(|element_arena| {
1057            let percentage = (element_arena.len() as f32 / element_arena.capacity() as f32) * 100.;
1058            if percentage >= 80. {
1059                log::warn!("elevated element arena occupation: {}.", percentage);
1060            }
1061            element_arena.clear();
1062        });
1063
1064        self.window.draw_phase = DrawPhase::Focus;
1065        let previous_focus_path = self.window.rendered_frame.focus_path();
1066        let previous_window_active = self.window.rendered_frame.window_active;
1067        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1068        self.window.next_frame.clear();
1069        let current_focus_path = self.window.rendered_frame.focus_path();
1070        let current_window_active = self.window.rendered_frame.window_active;
1071
1072        if previous_focus_path != current_focus_path
1073            || previous_window_active != current_window_active
1074        {
1075            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1076                self.window
1077                    .focus_lost_listeners
1078                    .clone()
1079                    .retain(&(), |listener| listener(self));
1080            }
1081
1082            let event = FocusEvent {
1083                previous_focus_path: if previous_window_active {
1084                    previous_focus_path
1085                } else {
1086                    Default::default()
1087                },
1088                current_focus_path: if current_window_active {
1089                    current_focus_path
1090                } else {
1091                    Default::default()
1092                },
1093            };
1094            self.window
1095                .focus_listeners
1096                .clone()
1097                .retain(&(), |listener| listener(&event, self));
1098        }
1099
1100        self.reset_cursor_style();
1101        self.window.refreshing = false;
1102        self.window.draw_phase = DrawPhase::None;
1103        self.window.needs_present.set(true);
1104    }
1105
1106    #[profiling::function]
1107    fn present(&self) {
1108        self.window
1109            .platform_window
1110            .draw(&self.window.rendered_frame.scene);
1111        self.window.needs_present.set(false);
1112        profiling::finish_frame!();
1113    }
1114
1115    fn reset_cursor_style(&self) {
1116        // Set the cursor only if we're the active window.
1117        if self.is_window_active() {
1118            let style = self
1119                .window
1120                .rendered_frame
1121                .cursor_styles
1122                .iter()
1123                .rev()
1124                .find(|request| request.hitbox_id.is_hovered(self))
1125                .map(|request| request.style)
1126                .unwrap_or(CursorStyle::Arrow);
1127            self.platform.set_cursor_style(style);
1128        }
1129    }
1130
1131    /// Dispatch a given keystroke as though the user had typed it.
1132    /// You can create a keystroke with Keystroke::parse("").
1133    pub fn dispatch_keystroke(&mut self, keystroke: Keystroke) -> bool {
1134        let keystroke = keystroke.with_simulated_ime();
1135        let result = self.dispatch_event(PlatformInput::KeyDown(KeyDownEvent {
1136            keystroke: keystroke.clone(),
1137            is_held: false,
1138        }));
1139        if !result.propagate {
1140            return true;
1141        }
1142
1143        if let Some(input) = keystroke.ime_key {
1144            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1145                input_handler.dispatch_input(&input, self);
1146                self.window.platform_window.set_input_handler(input_handler);
1147                return true;
1148            }
1149        }
1150
1151        false
1152    }
1153
1154    /// Represent this action as a key binding string, to display in the UI.
1155    pub fn keystroke_text_for(&self, action: &dyn Action) -> String {
1156        self.bindings_for_action(action)
1157            .into_iter()
1158            .next()
1159            .map(|binding| {
1160                binding
1161                    .keystrokes()
1162                    .iter()
1163                    .map(ToString::to_string)
1164                    .collect::<Vec<_>>()
1165                    .join(" ")
1166            })
1167            .unwrap_or_else(|| action.name().to_string())
1168    }
1169
1170    /// Dispatch a mouse or keyboard event on the window.
1171    #[profiling::function]
1172    pub fn dispatch_event(&mut self, event: PlatformInput) -> DispatchEventResult {
1173        self.window.last_input_timestamp.set(Instant::now());
1174        // Handlers may set this to false by calling `stop_propagation`.
1175        self.app.propagate_event = true;
1176        // Handlers may set this to true by calling `prevent_default`.
1177        self.window.default_prevented = false;
1178
1179        let event = match event {
1180            // Track the mouse position with our own state, since accessing the platform
1181            // API for the mouse position can only occur on the main thread.
1182            PlatformInput::MouseMove(mouse_move) => {
1183                self.window.mouse_position = mouse_move.position;
1184                self.window.modifiers = mouse_move.modifiers;
1185                PlatformInput::MouseMove(mouse_move)
1186            }
1187            PlatformInput::MouseDown(mouse_down) => {
1188                self.window.mouse_position = mouse_down.position;
1189                self.window.modifiers = mouse_down.modifiers;
1190                PlatformInput::MouseDown(mouse_down)
1191            }
1192            PlatformInput::MouseUp(mouse_up) => {
1193                self.window.mouse_position = mouse_up.position;
1194                self.window.modifiers = mouse_up.modifiers;
1195                PlatformInput::MouseUp(mouse_up)
1196            }
1197            PlatformInput::MouseExited(mouse_exited) => {
1198                self.window.modifiers = mouse_exited.modifiers;
1199                PlatformInput::MouseExited(mouse_exited)
1200            }
1201            PlatformInput::ModifiersChanged(modifiers_changed) => {
1202                self.window.modifiers = modifiers_changed.modifiers;
1203                PlatformInput::ModifiersChanged(modifiers_changed)
1204            }
1205            PlatformInput::ScrollWheel(scroll_wheel) => {
1206                self.window.mouse_position = scroll_wheel.position;
1207                self.window.modifiers = scroll_wheel.modifiers;
1208                PlatformInput::ScrollWheel(scroll_wheel)
1209            }
1210            // Translate dragging and dropping of external files from the operating system
1211            // to internal drag and drop events.
1212            PlatformInput::FileDrop(file_drop) => match file_drop {
1213                FileDropEvent::Entered { position, paths } => {
1214                    self.window.mouse_position = position;
1215                    if self.active_drag.is_none() {
1216                        self.active_drag = Some(AnyDrag {
1217                            value: Box::new(paths.clone()),
1218                            view: self.new_view(|_| paths).into(),
1219                            cursor_offset: position,
1220                        });
1221                    }
1222                    PlatformInput::MouseMove(MouseMoveEvent {
1223                        position,
1224                        pressed_button: Some(MouseButton::Left),
1225                        modifiers: Modifiers::default(),
1226                    })
1227                }
1228                FileDropEvent::Pending { position } => {
1229                    self.window.mouse_position = position;
1230                    PlatformInput::MouseMove(MouseMoveEvent {
1231                        position,
1232                        pressed_button: Some(MouseButton::Left),
1233                        modifiers: Modifiers::default(),
1234                    })
1235                }
1236                FileDropEvent::Submit { position } => {
1237                    self.activate(true);
1238                    self.window.mouse_position = position;
1239                    PlatformInput::MouseUp(MouseUpEvent {
1240                        button: MouseButton::Left,
1241                        position,
1242                        modifiers: Modifiers::default(),
1243                        click_count: 1,
1244                    })
1245                }
1246                FileDropEvent::Exited => {
1247                    self.active_drag.take();
1248                    PlatformInput::FileDrop(FileDropEvent::Exited)
1249                }
1250            },
1251            PlatformInput::KeyDown(_) | PlatformInput::KeyUp(_) => event,
1252        };
1253
1254        if let Some(any_mouse_event) = event.mouse_event() {
1255            self.dispatch_mouse_event(any_mouse_event);
1256        } else if let Some(any_key_event) = event.keyboard_event() {
1257            self.dispatch_key_event(any_key_event);
1258        }
1259
1260        DispatchEventResult {
1261            propagate: self.app.propagate_event,
1262            default_prevented: self.window.default_prevented,
1263        }
1264    }
1265
1266    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1267        let hit_test = self.window.rendered_frame.hit_test(self.mouse_position());
1268        if hit_test != self.window.mouse_hit_test {
1269            self.window.mouse_hit_test = hit_test;
1270            self.reset_cursor_style();
1271        }
1272
1273        let mut mouse_listeners = mem::take(&mut self.window.rendered_frame.mouse_listeners);
1274        self.with_element_context(|cx| {
1275            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1276            // special purposes, such as detecting events outside of a given Bounds.
1277            for listener in &mut mouse_listeners {
1278                let listener = listener.as_mut().unwrap();
1279                listener(event, DispatchPhase::Capture, cx);
1280                if !cx.app.propagate_event {
1281                    break;
1282                }
1283            }
1284
1285            // Bubble phase, where most normal handlers do their work.
1286            if cx.app.propagate_event {
1287                for listener in mouse_listeners.iter_mut().rev() {
1288                    let listener = listener.as_mut().unwrap();
1289                    listener(event, DispatchPhase::Bubble, cx);
1290                    if !cx.app.propagate_event {
1291                        break;
1292                    }
1293                }
1294            }
1295        });
1296        self.window.rendered_frame.mouse_listeners = mouse_listeners;
1297
1298        if self.app.propagate_event && self.has_active_drag() {
1299            if event.is::<MouseMoveEvent>() {
1300                // If this was a mouse move event, redraw the window so that the
1301                // active drag can follow the mouse cursor.
1302                self.refresh();
1303            } else if event.is::<MouseUpEvent>() {
1304                // If this was a mouse up event, cancel the active drag and redraw
1305                // the window.
1306                self.active_drag = None;
1307                self.refresh();
1308            }
1309        }
1310    }
1311
1312    fn dispatch_key_event(&mut self, event: &dyn Any) {
1313        if self.window.dirty.get() {
1314            self.draw();
1315        }
1316
1317        let node_id = self
1318            .window
1319            .focus
1320            .and_then(|focus_id| {
1321                self.window
1322                    .rendered_frame
1323                    .dispatch_tree
1324                    .focusable_node_id(focus_id)
1325            })
1326            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1327
1328        let dispatch_path = self
1329            .window
1330            .rendered_frame
1331            .dispatch_tree
1332            .dispatch_path(node_id);
1333
1334        if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1335            let KeymatchResult { bindings, pending } = self
1336                .window
1337                .rendered_frame
1338                .dispatch_tree
1339                .dispatch_key(&key_down_event.keystroke, &dispatch_path);
1340
1341            if pending {
1342                let mut currently_pending = self.window.pending_input.take().unwrap_or_default();
1343                if currently_pending.focus.is_some() && currently_pending.focus != self.window.focus
1344                {
1345                    currently_pending = PendingInput::default();
1346                }
1347                currently_pending.focus = self.window.focus;
1348                currently_pending
1349                    .keystrokes
1350                    .push(key_down_event.keystroke.clone());
1351                for binding in bindings {
1352                    currently_pending.bindings.push(binding);
1353                }
1354
1355                currently_pending.timer = Some(self.spawn(|mut cx| async move {
1356                    cx.background_executor.timer(Duration::from_secs(1)).await;
1357                    cx.update(move |cx| {
1358                        cx.clear_pending_keystrokes();
1359                        let Some(currently_pending) = cx.window.pending_input.take() else {
1360                            return;
1361                        };
1362                        cx.replay_pending_input(currently_pending)
1363                    })
1364                    .log_err();
1365                }));
1366
1367                self.window.pending_input = Some(currently_pending);
1368
1369                self.propagate_event = false;
1370                return;
1371            } else if let Some(currently_pending) = self.window.pending_input.take() {
1372                if bindings
1373                    .iter()
1374                    .all(|binding| !currently_pending.used_by_binding(binding))
1375                {
1376                    self.replay_pending_input(currently_pending)
1377                }
1378            }
1379
1380            if !bindings.is_empty() {
1381                self.clear_pending_keystrokes();
1382            }
1383
1384            self.propagate_event = true;
1385            for binding in bindings {
1386                self.dispatch_action_on_node(node_id, binding.action.as_ref());
1387                if !self.propagate_event {
1388                    self.dispatch_keystroke_observers(event, Some(binding.action));
1389                    return;
1390                }
1391            }
1392        }
1393
1394        self.dispatch_key_down_up_event(event, &dispatch_path);
1395        if !self.propagate_event {
1396            return;
1397        }
1398
1399        self.dispatch_modifiers_changed_event(event, &dispatch_path);
1400        if !self.propagate_event {
1401            return;
1402        }
1403
1404        self.dispatch_keystroke_observers(event, None);
1405    }
1406
1407    fn dispatch_key_down_up_event(
1408        &mut self,
1409        event: &dyn Any,
1410        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1411    ) {
1412        // Capture phase
1413        for node_id in dispatch_path {
1414            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1415
1416            for key_listener in node.key_listeners.clone() {
1417                self.with_element_context(|cx| {
1418                    key_listener(event, DispatchPhase::Capture, cx);
1419                });
1420                if !self.propagate_event {
1421                    return;
1422                }
1423            }
1424        }
1425
1426        // Bubble phase
1427        for node_id in dispatch_path.iter().rev() {
1428            // Handle low level key events
1429            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1430            for key_listener in node.key_listeners.clone() {
1431                self.with_element_context(|cx| {
1432                    key_listener(event, DispatchPhase::Bubble, cx);
1433                });
1434                if !self.propagate_event {
1435                    return;
1436                }
1437            }
1438        }
1439    }
1440
1441    fn dispatch_modifiers_changed_event(
1442        &mut self,
1443        event: &dyn Any,
1444        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1445    ) {
1446        let Some(event) = event.downcast_ref::<ModifiersChangedEvent>() else {
1447            return;
1448        };
1449        for node_id in dispatch_path.iter().rev() {
1450            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1451            for listener in node.modifiers_changed_listeners.clone() {
1452                self.with_element_context(|cx| {
1453                    listener(event, cx);
1454                });
1455                if !self.propagate_event {
1456                    return;
1457                }
1458            }
1459        }
1460    }
1461
1462    /// Determine whether a potential multi-stroke key binding is in progress on this window.
1463    pub fn has_pending_keystrokes(&self) -> bool {
1464        self.window
1465            .rendered_frame
1466            .dispatch_tree
1467            .has_pending_keystrokes()
1468    }
1469
1470    fn replay_pending_input(&mut self, currently_pending: PendingInput) {
1471        let node_id = self
1472            .window
1473            .focus
1474            .and_then(|focus_id| {
1475                self.window
1476                    .rendered_frame
1477                    .dispatch_tree
1478                    .focusable_node_id(focus_id)
1479            })
1480            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1481
1482        if self.window.focus != currently_pending.focus {
1483            return;
1484        }
1485
1486        let input = currently_pending.input();
1487
1488        self.propagate_event = true;
1489        for binding in currently_pending.bindings {
1490            self.dispatch_action_on_node(node_id, binding.action.as_ref());
1491            if !self.propagate_event {
1492                return;
1493            }
1494        }
1495
1496        let dispatch_path = self
1497            .window
1498            .rendered_frame
1499            .dispatch_tree
1500            .dispatch_path(node_id);
1501
1502        for keystroke in currently_pending.keystrokes {
1503            let event = KeyDownEvent {
1504                keystroke,
1505                is_held: false,
1506            };
1507
1508            self.dispatch_key_down_up_event(&event, &dispatch_path);
1509            if !self.propagate_event {
1510                return;
1511            }
1512        }
1513
1514        if !input.is_empty() {
1515            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1516                input_handler.dispatch_input(&input, self);
1517                self.window.platform_window.set_input_handler(input_handler)
1518            }
1519        }
1520    }
1521
1522    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: &dyn Action) {
1523        let dispatch_path = self
1524            .window
1525            .rendered_frame
1526            .dispatch_tree
1527            .dispatch_path(node_id);
1528
1529        // Capture phase for global actions.
1530        self.propagate_event = true;
1531        if let Some(mut global_listeners) = self
1532            .global_action_listeners
1533            .remove(&action.as_any().type_id())
1534        {
1535            for listener in &global_listeners {
1536                listener(action.as_any(), DispatchPhase::Capture, self);
1537                if !self.propagate_event {
1538                    break;
1539                }
1540            }
1541
1542            global_listeners.extend(
1543                self.global_action_listeners
1544                    .remove(&action.as_any().type_id())
1545                    .unwrap_or_default(),
1546            );
1547
1548            self.global_action_listeners
1549                .insert(action.as_any().type_id(), global_listeners);
1550        }
1551
1552        if !self.propagate_event {
1553            return;
1554        }
1555
1556        // Capture phase for window actions.
1557        for node_id in &dispatch_path {
1558            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1559            for DispatchActionListener {
1560                action_type,
1561                listener,
1562            } in node.action_listeners.clone()
1563            {
1564                let any_action = action.as_any();
1565                if action_type == any_action.type_id() {
1566                    self.with_element_context(|cx| {
1567                        listener(any_action, DispatchPhase::Capture, cx);
1568                    });
1569
1570                    if !self.propagate_event {
1571                        return;
1572                    }
1573                }
1574            }
1575        }
1576
1577        // Bubble phase for window actions.
1578        for node_id in dispatch_path.iter().rev() {
1579            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1580            for DispatchActionListener {
1581                action_type,
1582                listener,
1583            } in node.action_listeners.clone()
1584            {
1585                let any_action = action.as_any();
1586                if action_type == any_action.type_id() {
1587                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1588
1589                    self.with_element_context(|cx| {
1590                        listener(any_action, DispatchPhase::Bubble, cx);
1591                    });
1592
1593                    if !self.propagate_event {
1594                        return;
1595                    }
1596                }
1597            }
1598        }
1599
1600        // Bubble phase for global actions.
1601        if let Some(mut global_listeners) = self
1602            .global_action_listeners
1603            .remove(&action.as_any().type_id())
1604        {
1605            for listener in global_listeners.iter().rev() {
1606                self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1607
1608                listener(action.as_any(), DispatchPhase::Bubble, self);
1609                if !self.propagate_event {
1610                    break;
1611                }
1612            }
1613
1614            global_listeners.extend(
1615                self.global_action_listeners
1616                    .remove(&action.as_any().type_id())
1617                    .unwrap_or_default(),
1618            );
1619
1620            self.global_action_listeners
1621                .insert(action.as_any().type_id(), global_listeners);
1622        }
1623    }
1624
1625    /// Register the given handler to be invoked whenever the global of the given type
1626    /// is updated.
1627    pub fn observe_global<G: Global>(
1628        &mut self,
1629        f: impl Fn(&mut WindowContext<'_>) + 'static,
1630    ) -> Subscription {
1631        let window_handle = self.window.handle;
1632        let (subscription, activate) = self.global_observers.insert(
1633            TypeId::of::<G>(),
1634            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1635        );
1636        self.app.defer(move |_| activate());
1637        subscription
1638    }
1639
1640    /// Focus the current window and bring it to the foreground at the platform level.
1641    pub fn activate_window(&self) {
1642        self.window.platform_window.activate();
1643    }
1644
1645    /// Minimize the current window at the platform level.
1646    pub fn minimize_window(&self) {
1647        self.window.platform_window.minimize();
1648    }
1649
1650    /// Toggle full screen status on the current window at the platform level.
1651    pub fn toggle_fullscreen(&self) {
1652        self.window.platform_window.toggle_fullscreen();
1653    }
1654
1655    /// Present a platform dialog.
1656    /// The provided message will be presented, along with buttons for each answer.
1657    /// When a button is clicked, the returned Receiver will receive the index of the clicked button.
1658    pub fn prompt(
1659        &mut self,
1660        level: PromptLevel,
1661        message: &str,
1662        detail: Option<&str>,
1663        answers: &[&str],
1664    ) -> oneshot::Receiver<usize> {
1665        let prompt_builder = self.app.prompt_builder.take();
1666        let Some(prompt_builder) = prompt_builder else {
1667            unreachable!("Re-entrant window prompting is not supported by GPUI");
1668        };
1669
1670        let receiver = match &prompt_builder {
1671            PromptBuilder::Default => self
1672                .window
1673                .platform_window
1674                .prompt(level, message, detail, answers)
1675                .unwrap_or_else(|| {
1676                    self.build_custom_prompt(&prompt_builder, level, message, detail, answers)
1677                }),
1678            PromptBuilder::Custom(_) => {
1679                self.build_custom_prompt(&prompt_builder, level, message, detail, answers)
1680            }
1681        };
1682
1683        self.app.prompt_builder = Some(prompt_builder);
1684
1685        receiver
1686    }
1687
1688    fn build_custom_prompt(
1689        &mut self,
1690        prompt_builder: &PromptBuilder,
1691        level: PromptLevel,
1692        message: &str,
1693        detail: Option<&str>,
1694        answers: &[&str],
1695    ) -> oneshot::Receiver<usize> {
1696        let (sender, receiver) = oneshot::channel();
1697        let handle = PromptHandle::new(sender);
1698        let handle = (prompt_builder)(level, message, detail, answers, handle, self);
1699        self.window.prompt = Some(handle);
1700        receiver
1701    }
1702
1703    /// Returns all available actions for the focused element.
1704    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1705        let node_id = self
1706            .window
1707            .focus
1708            .and_then(|focus_id| {
1709                self.window
1710                    .rendered_frame
1711                    .dispatch_tree
1712                    .focusable_node_id(focus_id)
1713            })
1714            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1715
1716        let mut actions = self
1717            .window
1718            .rendered_frame
1719            .dispatch_tree
1720            .available_actions(node_id);
1721        for action_type in self.global_action_listeners.keys() {
1722            if let Err(ix) = actions.binary_search_by_key(action_type, |a| a.as_any().type_id()) {
1723                let action = self.actions.build_action_type(action_type).ok();
1724                if let Some(action) = action {
1725                    actions.insert(ix, action);
1726                }
1727            }
1728        }
1729        actions
1730    }
1731
1732    /// Returns key bindings that invoke the given action on the currently focused element.
1733    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1734        self.window
1735            .rendered_frame
1736            .dispatch_tree
1737            .bindings_for_action(
1738                action,
1739                &self.window.rendered_frame.dispatch_tree.context_stack,
1740            )
1741    }
1742
1743    /// Returns any bindings that would invoke the given action on the given focus handle if it were focused.
1744    pub fn bindings_for_action_in(
1745        &self,
1746        action: &dyn Action,
1747        focus_handle: &FocusHandle,
1748    ) -> Vec<KeyBinding> {
1749        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1750
1751        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1752            return vec![];
1753        };
1754        let context_stack: Vec<_> = dispatch_tree
1755            .dispatch_path(node_id)
1756            .into_iter()
1757            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1758            .collect();
1759        dispatch_tree.bindings_for_action(action, &context_stack)
1760    }
1761
1762    /// Returns a generic event listener that invokes the given listener with the view and context associated with the given view handle.
1763    pub fn listener_for<V: Render, E>(
1764        &self,
1765        view: &View<V>,
1766        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1767    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1768        let view = view.downgrade();
1769        move |e: &E, cx: &mut WindowContext| {
1770            view.update(cx, |view, cx| f(view, e, cx)).ok();
1771        }
1772    }
1773
1774    /// Returns a generic handler that invokes the given handler with the view and context associated with the given view handle.
1775    pub fn handler_for<V: Render>(
1776        &self,
1777        view: &View<V>,
1778        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1779    ) -> impl Fn(&mut WindowContext) {
1780        let view = view.downgrade();
1781        move |cx: &mut WindowContext| {
1782            view.update(cx, |view, cx| f(view, cx)).ok();
1783        }
1784    }
1785
1786    /// Register a callback that can interrupt the closing of the current window based the returned boolean.
1787    /// If the callback returns false, the window won't be closed.
1788    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1789        let mut this = self.to_async();
1790        self.window
1791            .platform_window
1792            .on_should_close(Box::new(move || this.update(|cx| f(cx)).unwrap_or(true)))
1793    }
1794
1795    /// Register an action listener on the window for the next frame. The type of action
1796    /// is determined by the first parameter of the given listener. When the next frame is rendered
1797    /// the listener will be cleared.
1798    ///
1799    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
1800    /// a specific need to register a global listener.
1801    pub fn on_action(
1802        &mut self,
1803        action_type: TypeId,
1804        listener: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
1805    ) {
1806        self.window
1807            .next_frame
1808            .dispatch_tree
1809            .on_action(action_type, Rc::new(listener));
1810    }
1811}
1812
1813#[cfg(target_os = "windows")]
1814impl WindowContext<'_> {
1815    /// Returns the raw HWND handle for the window.
1816    pub fn get_raw_handle(&self) -> windows::Win32::Foundation::HWND {
1817        self.window.platform_window.get_raw_handle()
1818    }
1819}
1820
1821impl Context for WindowContext<'_> {
1822    type Result<T> = T;
1823
1824    fn new_model<T>(&mut self, build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T) -> Model<T>
1825    where
1826        T: 'static,
1827    {
1828        let slot = self.app.entities.reserve();
1829        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1830        self.entities.insert(slot, model)
1831    }
1832
1833    fn update_model<T: 'static, R>(
1834        &mut self,
1835        model: &Model<T>,
1836        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1837    ) -> R {
1838        let mut entity = self.entities.lease(model);
1839        let result = update(
1840            &mut *entity,
1841            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1842        );
1843        self.entities.end_lease(entity);
1844        result
1845    }
1846
1847    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1848    where
1849        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1850    {
1851        if window == self.window.handle {
1852            let root_view = self.window.root_view.clone().unwrap();
1853            Ok(update(root_view, self))
1854        } else {
1855            window.update(self.app, update)
1856        }
1857    }
1858
1859    fn read_model<T, R>(
1860        &self,
1861        handle: &Model<T>,
1862        read: impl FnOnce(&T, &AppContext) -> R,
1863    ) -> Self::Result<R>
1864    where
1865        T: 'static,
1866    {
1867        let entity = self.entities.read(handle);
1868        read(entity, &*self.app)
1869    }
1870
1871    fn read_window<T, R>(
1872        &self,
1873        window: &WindowHandle<T>,
1874        read: impl FnOnce(View<T>, &AppContext) -> R,
1875    ) -> Result<R>
1876    where
1877        T: 'static,
1878    {
1879        if window.any_handle == self.window.handle {
1880            let root_view = self
1881                .window
1882                .root_view
1883                .clone()
1884                .unwrap()
1885                .downcast::<T>()
1886                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1887            Ok(read(root_view, self))
1888        } else {
1889            self.app.read_window(window, read)
1890        }
1891    }
1892}
1893
1894impl VisualContext for WindowContext<'_> {
1895    fn new_view<V>(
1896        &mut self,
1897        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1898    ) -> Self::Result<View<V>>
1899    where
1900        V: 'static + Render,
1901    {
1902        let slot = self.app.entities.reserve();
1903        let view = View {
1904            model: slot.clone(),
1905        };
1906        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1907        let entity = build_view_state(&mut cx);
1908        cx.entities.insert(slot, entity);
1909
1910        // Non-generic part to avoid leaking SubscriberSet to invokers of `new_view`.
1911        fn notify_observers(cx: &mut WindowContext, tid: TypeId, view: AnyView) {
1912            cx.new_view_observers.clone().retain(&tid, |observer| {
1913                let any_view = view.clone();
1914                (observer)(any_view, cx);
1915                true
1916            });
1917        }
1918        notify_observers(self, TypeId::of::<V>(), AnyView::from(view.clone()));
1919
1920        view
1921    }
1922
1923    /// Updates the given view. Prefer calling [`View::update`] instead, which calls this method.
1924    fn update_view<T: 'static, R>(
1925        &mut self,
1926        view: &View<T>,
1927        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1928    ) -> Self::Result<R> {
1929        let mut lease = self.app.entities.lease(&view.model);
1930        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, view);
1931        let result = update(&mut *lease, &mut cx);
1932        cx.app.entities.end_lease(lease);
1933        result
1934    }
1935
1936    fn replace_root_view<V>(
1937        &mut self,
1938        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1939    ) -> Self::Result<View<V>>
1940    where
1941        V: 'static + Render,
1942    {
1943        let view = self.new_view(build_view);
1944        self.window.root_view = Some(view.clone().into());
1945        self.refresh();
1946        view
1947    }
1948
1949    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1950        self.update_view(view, |view, cx| {
1951            view.focus_handle(cx).clone().focus(cx);
1952        })
1953    }
1954
1955    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1956    where
1957        V: ManagedView,
1958    {
1959        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1960    }
1961}
1962
1963impl<'a> std::ops::Deref for WindowContext<'a> {
1964    type Target = AppContext;
1965
1966    fn deref(&self) -> &Self::Target {
1967        self.app
1968    }
1969}
1970
1971impl<'a> std::ops::DerefMut for WindowContext<'a> {
1972    fn deref_mut(&mut self) -> &mut Self::Target {
1973        self.app
1974    }
1975}
1976
1977impl<'a> Borrow<AppContext> for WindowContext<'a> {
1978    fn borrow(&self) -> &AppContext {
1979        self.app
1980    }
1981}
1982
1983impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1984    fn borrow_mut(&mut self) -> &mut AppContext {
1985        self.app
1986    }
1987}
1988
1989/// This trait contains functionality that is shared across [`ViewContext`] and [`WindowContext`]
1990pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1991    #[doc(hidden)]
1992    fn app_mut(&mut self) -> &mut AppContext {
1993        self.borrow_mut()
1994    }
1995
1996    #[doc(hidden)]
1997    fn app(&self) -> &AppContext {
1998        self.borrow()
1999    }
2000
2001    #[doc(hidden)]
2002    fn window(&self) -> &Window {
2003        self.borrow()
2004    }
2005
2006    #[doc(hidden)]
2007    fn window_mut(&mut self) -> &mut Window {
2008        self.borrow_mut()
2009    }
2010}
2011
2012impl Borrow<Window> for WindowContext<'_> {
2013    fn borrow(&self) -> &Window {
2014        self.window
2015    }
2016}
2017
2018impl BorrowMut<Window> for WindowContext<'_> {
2019    fn borrow_mut(&mut self) -> &mut Window {
2020        self.window
2021    }
2022}
2023
2024impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
2025
2026/// Provides access to application state that is specialized for a particular [`View`].
2027/// Allows you to interact with focus, emit events, etc.
2028/// ViewContext also derefs to [`WindowContext`], giving you access to all of its methods as well.
2029/// When you call [`View::update`], you're passed a `&mut V` and an `&mut ViewContext<V>`.
2030pub struct ViewContext<'a, V> {
2031    window_cx: WindowContext<'a>,
2032    view: &'a View<V>,
2033}
2034
2035impl<V> Borrow<AppContext> for ViewContext<'_, V> {
2036    fn borrow(&self) -> &AppContext {
2037        &*self.window_cx.app
2038    }
2039}
2040
2041impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
2042    fn borrow_mut(&mut self) -> &mut AppContext {
2043        &mut *self.window_cx.app
2044    }
2045}
2046
2047impl<V> Borrow<Window> for ViewContext<'_, V> {
2048    fn borrow(&self) -> &Window {
2049        &*self.window_cx.window
2050    }
2051}
2052
2053impl<V> BorrowMut<Window> for ViewContext<'_, V> {
2054    fn borrow_mut(&mut self) -> &mut Window {
2055        &mut *self.window_cx.window
2056    }
2057}
2058
2059impl<'a, V: 'static> ViewContext<'a, V> {
2060    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
2061        Self {
2062            window_cx: WindowContext::new(app, window),
2063            view,
2064        }
2065    }
2066
2067    /// Get the entity_id of this view.
2068    pub fn entity_id(&self) -> EntityId {
2069        self.view.entity_id()
2070    }
2071
2072    /// Get the view pointer underlying this context.
2073    pub fn view(&self) -> &View<V> {
2074        self.view
2075    }
2076
2077    /// Get the model underlying this view.
2078    pub fn model(&self) -> &Model<V> {
2079        &self.view.model
2080    }
2081
2082    /// Access the underlying window context.
2083    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2084        &mut self.window_cx
2085    }
2086
2087    /// Sets a given callback to be run on the next frame.
2088    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
2089    where
2090        V: 'static,
2091    {
2092        let view = self.view().clone();
2093        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
2094    }
2095
2096    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
2097    /// that are currently on the stack to be returned to the app.
2098    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
2099        let view = self.view().downgrade();
2100        self.window_cx.defer(move |cx| {
2101            view.update(cx, f).ok();
2102        });
2103    }
2104
2105    /// Observe another model or view for changes to its state, as tracked by [`ModelContext::notify`].
2106    pub fn observe<V2, E>(
2107        &mut self,
2108        entity: &E,
2109        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
2110    ) -> Subscription
2111    where
2112        V2: 'static,
2113        V: 'static,
2114        E: Entity<V2>,
2115    {
2116        let view = self.view().downgrade();
2117        let entity_id = entity.entity_id();
2118        let entity = entity.downgrade();
2119        let window_handle = self.window.handle;
2120        self.app.new_observer(
2121            entity_id,
2122            Box::new(move |cx| {
2123                window_handle
2124                    .update(cx, |_, cx| {
2125                        if let Some(handle) = E::upgrade_from(&entity) {
2126                            view.update(cx, |this, cx| on_notify(this, handle, cx))
2127                                .is_ok()
2128                        } else {
2129                            false
2130                        }
2131                    })
2132                    .unwrap_or(false)
2133            }),
2134        )
2135    }
2136
2137    /// Subscribe to events emitted by another model or view.
2138    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
2139    /// The callback will be invoked with a reference to the current view, a handle to the emitting entity (either a [`View`] or [`Model`]), the event, and a view context for the current view.
2140    pub fn subscribe<V2, E, Evt>(
2141        &mut self,
2142        entity: &E,
2143        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2144    ) -> Subscription
2145    where
2146        V2: EventEmitter<Evt>,
2147        E: Entity<V2>,
2148        Evt: 'static,
2149    {
2150        let view = self.view().downgrade();
2151        let entity_id = entity.entity_id();
2152        let handle = entity.downgrade();
2153        let window_handle = self.window.handle;
2154        self.app.new_subscription(
2155            entity_id,
2156            (
2157                TypeId::of::<Evt>(),
2158                Box::new(move |event, cx| {
2159                    window_handle
2160                        .update(cx, |_, cx| {
2161                            if let Some(handle) = E::upgrade_from(&handle) {
2162                                let event = event.downcast_ref().expect("invalid event type");
2163                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2164                                    .is_ok()
2165                            } else {
2166                                false
2167                            }
2168                        })
2169                        .unwrap_or(false)
2170                }),
2171            ),
2172        )
2173    }
2174
2175    /// Register a callback to be invoked when the view is released.
2176    ///
2177    /// The callback receives a handle to the view's window. This handle may be
2178    /// invalid, if the window was closed before the view was released.
2179    pub fn on_release(
2180        &mut self,
2181        on_release: impl FnOnce(&mut V, AnyWindowHandle, &mut AppContext) + 'static,
2182    ) -> Subscription {
2183        let window_handle = self.window.handle;
2184        let (subscription, activate) = self.app.release_listeners.insert(
2185            self.view.model.entity_id,
2186            Box::new(move |this, cx| {
2187                let this = this.downcast_mut().expect("invalid entity type");
2188                on_release(this, window_handle, cx)
2189            }),
2190        );
2191        activate();
2192        subscription
2193    }
2194
2195    /// Register a callback to be invoked when the given Model or View is released.
2196    pub fn observe_release<V2, E>(
2197        &mut self,
2198        entity: &E,
2199        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2200    ) -> Subscription
2201    where
2202        V: 'static,
2203        V2: 'static,
2204        E: Entity<V2>,
2205    {
2206        let view = self.view().downgrade();
2207        let entity_id = entity.entity_id();
2208        let window_handle = self.window.handle;
2209        let (subscription, activate) = self.app.release_listeners.insert(
2210            entity_id,
2211            Box::new(move |entity, cx| {
2212                let entity = entity.downcast_mut().expect("invalid entity type");
2213                let _ = window_handle.update(cx, |_, cx| {
2214                    view.update(cx, |this, cx| on_release(this, entity, cx))
2215                });
2216            }),
2217        );
2218        activate();
2219        subscription
2220    }
2221
2222    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
2223    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
2224    pub fn notify(&mut self) {
2225        self.window_cx.notify(self.view.entity_id());
2226    }
2227
2228    /// Register a callback to be invoked when the window is resized.
2229    pub fn observe_window_bounds(
2230        &mut self,
2231        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2232    ) -> Subscription {
2233        let view = self.view.downgrade();
2234        let (subscription, activate) = self.window.bounds_observers.insert(
2235            (),
2236            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2237        );
2238        activate();
2239        subscription
2240    }
2241
2242    /// Register a callback to be invoked when the window is activated or deactivated.
2243    pub fn observe_window_activation(
2244        &mut self,
2245        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2246    ) -> Subscription {
2247        let view = self.view.downgrade();
2248        let (subscription, activate) = self.window.activation_observers.insert(
2249            (),
2250            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2251        );
2252        activate();
2253        subscription
2254    }
2255
2256    /// Registers a callback to be invoked when the window appearance changes.
2257    pub fn observe_window_appearance(
2258        &mut self,
2259        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2260    ) -> Subscription {
2261        let view = self.view.downgrade();
2262        let (subscription, activate) = self.window.appearance_observers.insert(
2263            (),
2264            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2265        );
2266        activate();
2267        subscription
2268    }
2269
2270    /// Register a listener to be called when the given focus handle receives focus.
2271    /// Returns a subscription and persists until the subscription is dropped.
2272    pub fn on_focus(
2273        &mut self,
2274        handle: &FocusHandle,
2275        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2276    ) -> Subscription {
2277        let view = self.view.downgrade();
2278        let focus_id = handle.id;
2279        let (subscription, activate) =
2280            self.window.new_focus_listener(Box::new(move |event, cx| {
2281                view.update(cx, |view, cx| {
2282                    if event.previous_focus_path.last() != Some(&focus_id)
2283                        && event.current_focus_path.last() == Some(&focus_id)
2284                    {
2285                        listener(view, cx)
2286                    }
2287                })
2288                .is_ok()
2289            }));
2290        self.app.defer(|_| activate());
2291        subscription
2292    }
2293
2294    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2295    /// Returns a subscription and persists until the subscription is dropped.
2296    pub fn on_focus_in(
2297        &mut self,
2298        handle: &FocusHandle,
2299        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2300    ) -> Subscription {
2301        let view = self.view.downgrade();
2302        let focus_id = handle.id;
2303        let (subscription, activate) =
2304            self.window.new_focus_listener(Box::new(move |event, cx| {
2305                view.update(cx, |view, cx| {
2306                    if !event.previous_focus_path.contains(&focus_id)
2307                        && event.current_focus_path.contains(&focus_id)
2308                    {
2309                        listener(view, cx)
2310                    }
2311                })
2312                .is_ok()
2313            }));
2314        self.app.defer(move |_| activate());
2315        subscription
2316    }
2317
2318    /// Register a listener to be called when the given focus handle loses focus.
2319    /// Returns a subscription and persists until the subscription is dropped.
2320    pub fn on_blur(
2321        &mut self,
2322        handle: &FocusHandle,
2323        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2324    ) -> Subscription {
2325        let view = self.view.downgrade();
2326        let focus_id = handle.id;
2327        let (subscription, activate) =
2328            self.window.new_focus_listener(Box::new(move |event, cx| {
2329                view.update(cx, |view, cx| {
2330                    if event.previous_focus_path.last() == Some(&focus_id)
2331                        && event.current_focus_path.last() != Some(&focus_id)
2332                    {
2333                        listener(view, cx)
2334                    }
2335                })
2336                .is_ok()
2337            }));
2338        self.app.defer(move |_| activate());
2339        subscription
2340    }
2341
2342    /// Register a listener to be called when nothing in the window has focus.
2343    /// This typically happens when the node that was focused is removed from the tree,
2344    /// and this callback lets you chose a default place to restore the users focus.
2345    /// Returns a subscription and persists until the subscription is dropped.
2346    pub fn on_focus_lost(
2347        &mut self,
2348        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2349    ) -> Subscription {
2350        let view = self.view.downgrade();
2351        let (subscription, activate) = self.window.focus_lost_listeners.insert(
2352            (),
2353            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2354        );
2355        activate();
2356        subscription
2357    }
2358
2359    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2360    /// Returns a subscription and persists until the subscription is dropped.
2361    pub fn on_focus_out(
2362        &mut self,
2363        handle: &FocusHandle,
2364        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2365    ) -> Subscription {
2366        let view = self.view.downgrade();
2367        let focus_id = handle.id;
2368        let (subscription, activate) =
2369            self.window.new_focus_listener(Box::new(move |event, cx| {
2370                view.update(cx, |view, cx| {
2371                    if event.previous_focus_path.contains(&focus_id)
2372                        && !event.current_focus_path.contains(&focus_id)
2373                    {
2374                        listener(view, cx)
2375                    }
2376                })
2377                .is_ok()
2378            }));
2379        self.app.defer(move |_| activate());
2380        subscription
2381    }
2382
2383    /// Schedule a future to be run asynchronously.
2384    /// The given callback is invoked with a [`WeakView<V>`] to avoid leaking the view for a long-running process.
2385    /// It's also given an [`AsyncWindowContext`], which can be used to access the state of the view across await points.
2386    /// The returned future will be polled on the main thread.
2387    pub fn spawn<Fut, R>(
2388        &mut self,
2389        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2390    ) -> Task<R>
2391    where
2392        R: 'static,
2393        Fut: Future<Output = R> + 'static,
2394    {
2395        let view = self.view().downgrade();
2396        self.window_cx.spawn(|cx| f(view, cx))
2397    }
2398
2399    /// Register a callback to be invoked when the given global state changes.
2400    pub fn observe_global<G: Global>(
2401        &mut self,
2402        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2403    ) -> Subscription {
2404        let window_handle = self.window.handle;
2405        let view = self.view().downgrade();
2406        let (subscription, activate) = self.global_observers.insert(
2407            TypeId::of::<G>(),
2408            Box::new(move |cx| {
2409                window_handle
2410                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2411                    .unwrap_or(false)
2412            }),
2413        );
2414        self.app.defer(move |_| activate());
2415        subscription
2416    }
2417
2418    /// Register a callback to be invoked when the given Action type is dispatched to the window.
2419    pub fn on_action(
2420        &mut self,
2421        action_type: TypeId,
2422        listener: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2423    ) {
2424        let handle = self.view().clone();
2425        self.window_cx
2426            .on_action(action_type, move |action, phase, cx| {
2427                handle.update(cx, |view, cx| {
2428                    listener(view, action, phase, cx);
2429                })
2430            });
2431    }
2432
2433    /// Emit an event to be handled any other views that have subscribed via [ViewContext::subscribe].
2434    pub fn emit<Evt>(&mut self, event: Evt)
2435    where
2436        Evt: 'static,
2437        V: EventEmitter<Evt>,
2438    {
2439        let emitter = self.view.model.entity_id;
2440        self.app.push_effect(Effect::Emit {
2441            emitter,
2442            event_type: TypeId::of::<Evt>(),
2443            event: Box::new(event),
2444        });
2445    }
2446
2447    /// Move focus to the current view, assuming it implements [`FocusableView`].
2448    pub fn focus_self(&mut self)
2449    where
2450        V: FocusableView,
2451    {
2452        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2453    }
2454
2455    /// Convenience method for accessing view state in an event callback.
2456    ///
2457    /// Many GPUI callbacks take the form of `Fn(&E, &mut WindowContext)`,
2458    /// but it's often useful to be able to access view state in these
2459    /// callbacks. This method provides a convenient way to do so.
2460    pub fn listener<E>(
2461        &self,
2462        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2463    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2464        let view = self.view().downgrade();
2465        move |e: &E, cx: &mut WindowContext| {
2466            view.update(cx, |view, cx| f(view, e, cx)).ok();
2467        }
2468    }
2469}
2470
2471impl<V> Context for ViewContext<'_, V> {
2472    type Result<U> = U;
2473
2474    fn new_model<T: 'static>(
2475        &mut self,
2476        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2477    ) -> Model<T> {
2478        self.window_cx.new_model(build_model)
2479    }
2480
2481    fn update_model<T: 'static, R>(
2482        &mut self,
2483        model: &Model<T>,
2484        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2485    ) -> R {
2486        self.window_cx.update_model(model, update)
2487    }
2488
2489    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2490    where
2491        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2492    {
2493        self.window_cx.update_window(window, update)
2494    }
2495
2496    fn read_model<T, R>(
2497        &self,
2498        handle: &Model<T>,
2499        read: impl FnOnce(&T, &AppContext) -> R,
2500    ) -> Self::Result<R>
2501    where
2502        T: 'static,
2503    {
2504        self.window_cx.read_model(handle, read)
2505    }
2506
2507    fn read_window<T, R>(
2508        &self,
2509        window: &WindowHandle<T>,
2510        read: impl FnOnce(View<T>, &AppContext) -> R,
2511    ) -> Result<R>
2512    where
2513        T: 'static,
2514    {
2515        self.window_cx.read_window(window, read)
2516    }
2517}
2518
2519impl<V: 'static> VisualContext for ViewContext<'_, V> {
2520    fn new_view<W: Render + 'static>(
2521        &mut self,
2522        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2523    ) -> Self::Result<View<W>> {
2524        self.window_cx.new_view(build_view_state)
2525    }
2526
2527    fn update_view<V2: 'static, R>(
2528        &mut self,
2529        view: &View<V2>,
2530        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2531    ) -> Self::Result<R> {
2532        self.window_cx.update_view(view, update)
2533    }
2534
2535    fn replace_root_view<W>(
2536        &mut self,
2537        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2538    ) -> Self::Result<View<W>>
2539    where
2540        W: 'static + Render,
2541    {
2542        self.window_cx.replace_root_view(build_view)
2543    }
2544
2545    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2546        self.window_cx.focus_view(view)
2547    }
2548
2549    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2550        self.window_cx.dismiss_view(view)
2551    }
2552}
2553
2554impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2555    type Target = WindowContext<'a>;
2556
2557    fn deref(&self) -> &Self::Target {
2558        &self.window_cx
2559    }
2560}
2561
2562impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2563    fn deref_mut(&mut self) -> &mut Self::Target {
2564        &mut self.window_cx
2565    }
2566}
2567
2568// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2569slotmap::new_key_type! {
2570    /// A unique identifier for a window.
2571    pub struct WindowId;
2572}
2573
2574impl WindowId {
2575    /// Converts this window ID to a `u64`.
2576    pub fn as_u64(&self) -> u64 {
2577        self.0.as_ffi()
2578    }
2579}
2580
2581/// A handle to a window with a specific root view type.
2582/// Note that this does not keep the window alive on its own.
2583#[derive(Deref, DerefMut)]
2584pub struct WindowHandle<V> {
2585    #[deref]
2586    #[deref_mut]
2587    pub(crate) any_handle: AnyWindowHandle,
2588    state_type: PhantomData<V>,
2589}
2590
2591impl<V: 'static + Render> WindowHandle<V> {
2592    /// Creates a new handle from a window ID.
2593    /// This does not check if the root type of the window is `V`.
2594    pub fn new(id: WindowId) -> Self {
2595        WindowHandle {
2596            any_handle: AnyWindowHandle {
2597                id,
2598                state_type: TypeId::of::<V>(),
2599            },
2600            state_type: PhantomData,
2601        }
2602    }
2603
2604    /// Get the root view out of this window.
2605    ///
2606    /// This will fail if the window is closed or if the root view's type does not match `V`.
2607    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2608    where
2609        C: Context,
2610    {
2611        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2612            root_view
2613                .downcast::<V>()
2614                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2615        }))
2616    }
2617
2618    /// Updates the root view of this window.
2619    ///
2620    /// This will fail if the window has been closed or if the root view's type does not match
2621    pub fn update<C, R>(
2622        &self,
2623        cx: &mut C,
2624        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2625    ) -> Result<R>
2626    where
2627        C: Context,
2628    {
2629        cx.update_window(self.any_handle, |root_view, cx| {
2630            let view = root_view
2631                .downcast::<V>()
2632                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2633            Ok(cx.update_view(&view, update))
2634        })?
2635    }
2636
2637    /// Read the root view out of this window.
2638    ///
2639    /// This will fail if the window is closed or if the root view's type does not match `V`.
2640    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2641        let x = cx
2642            .windows
2643            .get(self.id)
2644            .and_then(|window| {
2645                window
2646                    .as_ref()
2647                    .and_then(|window| window.root_view.clone())
2648                    .map(|root_view| root_view.downcast::<V>())
2649            })
2650            .ok_or_else(|| anyhow!("window not found"))?
2651            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2652
2653        Ok(x.read(cx))
2654    }
2655
2656    /// Read the root view out of this window, with a callback
2657    ///
2658    /// This will fail if the window is closed or if the root view's type does not match `V`.
2659    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2660    where
2661        C: Context,
2662    {
2663        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2664    }
2665
2666    /// Read the root view pointer off of this window.
2667    ///
2668    /// This will fail if the window is closed or if the root view's type does not match `V`.
2669    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2670    where
2671        C: Context,
2672    {
2673        cx.read_window(self, |root_view, _cx| root_view.clone())
2674    }
2675
2676    /// Check if this window is 'active'.
2677    ///
2678    /// Will return `None` if the window is closed or currently
2679    /// borrowed.
2680    pub fn is_active(&self, cx: &mut AppContext) -> Option<bool> {
2681        cx.update_window(self.any_handle, |_, cx| cx.is_window_active())
2682            .ok()
2683    }
2684}
2685
2686impl<V> Copy for WindowHandle<V> {}
2687
2688impl<V> Clone for WindowHandle<V> {
2689    fn clone(&self) -> Self {
2690        *self
2691    }
2692}
2693
2694impl<V> PartialEq for WindowHandle<V> {
2695    fn eq(&self, other: &Self) -> bool {
2696        self.any_handle == other.any_handle
2697    }
2698}
2699
2700impl<V> Eq for WindowHandle<V> {}
2701
2702impl<V> Hash for WindowHandle<V> {
2703    fn hash<H: Hasher>(&self, state: &mut H) {
2704        self.any_handle.hash(state);
2705    }
2706}
2707
2708impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle {
2709    fn from(val: WindowHandle<V>) -> Self {
2710        val.any_handle
2711    }
2712}
2713
2714/// A handle to a window with any root view type, which can be downcast to a window with a specific root view type.
2715#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2716pub struct AnyWindowHandle {
2717    pub(crate) id: WindowId,
2718    state_type: TypeId,
2719}
2720
2721impl AnyWindowHandle {
2722    /// Get the ID of this window.
2723    pub fn window_id(&self) -> WindowId {
2724        self.id
2725    }
2726
2727    /// Attempt to convert this handle to a window handle with a specific root view type.
2728    /// If the types do not match, this will return `None`.
2729    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2730        if TypeId::of::<T>() == self.state_type {
2731            Some(WindowHandle {
2732                any_handle: *self,
2733                state_type: PhantomData,
2734            })
2735        } else {
2736            None
2737        }
2738    }
2739
2740    /// Updates the state of the root view of this window.
2741    ///
2742    /// This will fail if the window has been closed.
2743    pub fn update<C, R>(
2744        self,
2745        cx: &mut C,
2746        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2747    ) -> Result<R>
2748    where
2749        C: Context,
2750    {
2751        cx.update_window(self, update)
2752    }
2753
2754    /// Read the state of the root view of this window.
2755    ///
2756    /// This will fail if the window has been closed.
2757    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2758    where
2759        C: Context,
2760        T: 'static,
2761    {
2762        let view = self
2763            .downcast::<T>()
2764            .context("the type of the window's root view has changed")?;
2765
2766        cx.read_window(&view, read)
2767    }
2768}
2769
2770/// An identifier for an [`Element`](crate::Element).
2771///
2772/// Can be constructed with a string, a number, or both, as well
2773/// as other internal representations.
2774#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2775pub enum ElementId {
2776    /// The ID of a View element
2777    View(EntityId),
2778    /// An integer ID.
2779    Integer(usize),
2780    /// A string based ID.
2781    Name(SharedString),
2782    /// An ID that's equated with a focus handle.
2783    FocusHandle(FocusId),
2784    /// A combination of a name and an integer.
2785    NamedInteger(SharedString, usize),
2786}
2787
2788impl Display for ElementId {
2789    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
2790        match self {
2791            ElementId::View(entity_id) => write!(f, "view-{}", entity_id)?,
2792            ElementId::Integer(ix) => write!(f, "{}", ix)?,
2793            ElementId::Name(name) => write!(f, "{}", name)?,
2794            ElementId::FocusHandle(_) => write!(f, "FocusHandle")?,
2795            ElementId::NamedInteger(s, i) => write!(f, "{}-{}", s, i)?,
2796        }
2797
2798        Ok(())
2799    }
2800}
2801
2802impl TryInto<SharedString> for ElementId {
2803    type Error = anyhow::Error;
2804
2805    fn try_into(self) -> anyhow::Result<SharedString> {
2806        if let ElementId::Name(name) = self {
2807            Ok(name)
2808        } else {
2809            Err(anyhow!("element id is not string"))
2810        }
2811    }
2812}
2813
2814impl From<usize> for ElementId {
2815    fn from(id: usize) -> Self {
2816        ElementId::Integer(id)
2817    }
2818}
2819
2820impl From<i32> for ElementId {
2821    fn from(id: i32) -> Self {
2822        Self::Integer(id as usize)
2823    }
2824}
2825
2826impl From<SharedString> for ElementId {
2827    fn from(name: SharedString) -> Self {
2828        ElementId::Name(name)
2829    }
2830}
2831
2832impl From<&'static str> for ElementId {
2833    fn from(name: &'static str) -> Self {
2834        ElementId::Name(name.into())
2835    }
2836}
2837
2838impl<'a> From<&'a FocusHandle> for ElementId {
2839    fn from(handle: &'a FocusHandle) -> Self {
2840        ElementId::FocusHandle(handle.id)
2841    }
2842}
2843
2844impl From<(&'static str, EntityId)> for ElementId {
2845    fn from((name, id): (&'static str, EntityId)) -> Self {
2846        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2847    }
2848}
2849
2850impl From<(&'static str, usize)> for ElementId {
2851    fn from((name, id): (&'static str, usize)) -> Self {
2852        ElementId::NamedInteger(name.into(), id)
2853    }
2854}
2855
2856impl From<(&'static str, u64)> for ElementId {
2857    fn from((name, id): (&'static str, u64)) -> Self {
2858        ElementId::NamedInteger(name.into(), id as usize)
2859    }
2860}
2861
2862/// A rectangle to be rendered in the window at the given position and size.
2863/// Passed as an argument [`ElementContext::paint_quad`].
2864#[derive(Clone)]
2865pub struct PaintQuad {
2866    /// The bounds of the quad within the window.
2867    pub bounds: Bounds<Pixels>,
2868    /// The radii of the quad's corners.
2869    pub corner_radii: Corners<Pixels>,
2870    /// The background color of the quad.
2871    pub background: Hsla,
2872    /// The widths of the quad's borders.
2873    pub border_widths: Edges<Pixels>,
2874    /// The color of the quad's borders.
2875    pub border_color: Hsla,
2876}
2877
2878impl PaintQuad {
2879    /// Sets the corner radii of the quad.
2880    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
2881        PaintQuad {
2882            corner_radii: corner_radii.into(),
2883            ..self
2884        }
2885    }
2886
2887    /// Sets the border widths of the quad.
2888    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
2889        PaintQuad {
2890            border_widths: border_widths.into(),
2891            ..self
2892        }
2893    }
2894
2895    /// Sets the border color of the quad.
2896    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
2897        PaintQuad {
2898            border_color: border_color.into(),
2899            ..self
2900        }
2901    }
2902
2903    /// Sets the background color of the quad.
2904    pub fn background(self, background: impl Into<Hsla>) -> Self {
2905        PaintQuad {
2906            background: background.into(),
2907            ..self
2908        }
2909    }
2910}
2911
2912/// Creates a quad with the given parameters.
2913pub fn quad(
2914    bounds: Bounds<Pixels>,
2915    corner_radii: impl Into<Corners<Pixels>>,
2916    background: impl Into<Hsla>,
2917    border_widths: impl Into<Edges<Pixels>>,
2918    border_color: impl Into<Hsla>,
2919) -> PaintQuad {
2920    PaintQuad {
2921        bounds,
2922        corner_radii: corner_radii.into(),
2923        background: background.into(),
2924        border_widths: border_widths.into(),
2925        border_color: border_color.into(),
2926    }
2927}
2928
2929/// Creates a filled quad with the given bounds and background color.
2930pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
2931    PaintQuad {
2932        bounds: bounds.into(),
2933        corner_radii: (0.).into(),
2934        background: background.into(),
2935        border_widths: (0.).into(),
2936        border_color: transparent_black(),
2937    }
2938}
2939
2940/// Creates a rectangle outline with the given bounds, border color, and a 1px border width
2941pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
2942    PaintQuad {
2943        bounds: bounds.into(),
2944        corner_radii: (0.).into(),
2945        background: transparent_black(),
2946        border_widths: (1.).into(),
2947        border_color: border_color.into(),
2948    }
2949}