1use crate::{
   2    point, px, size, transparent_black, Action, AnyDrag, AnyView, AppContext, Arena,
   3    AsyncWindowContext, Bounds, Context, Corners, CursorStyle, DispatchActionListener,
   4    DispatchNodeId, DispatchTree, DisplayId, Edges, Effect, Entity, EntityId, EventEmitter,
   5    FileDropEvent, Flatten, Global, GlobalElementId, GlobalPixels, Hsla, KeyBinding, KeyDownEvent,
   6    KeyMatch, KeymatchResult, Keystroke, KeystrokeEvent, Model, ModelContext, Modifiers,
   7    ModifiersChangedEvent, MouseButton, MouseMoveEvent, MouseUpEvent, Pixels, PlatformAtlas,
   8    PlatformDisplay, PlatformInput, PlatformWindow, Point, PromptLevel, Render, ScaledPixels,
   9    SharedString, Size, SubscriberSet, Subscription, TaffyLayoutEngine, Task, TextStyle,
  10    TextStyleRefinement, View, VisualContext, WeakView, WindowAppearance, WindowOptions,
  11    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(cx: &mut AppContext) -> Bounds<GlobalPixels> {
 362    const DEFAULT_WINDOW_SIZE: Size<GlobalPixels> = size(GlobalPixels(1024.0), GlobalPixels(700.0));
 363    const DEFAULT_WINDOW_OFFSET: Point<GlobalPixels> = point(GlobalPixels(0.0), GlobalPixels(35.0));
 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            cx.primary_display()
 370                .map(|display| {
 371                    let center = display.bounds().center();
 372                    let offset = DEFAULT_WINDOW_SIZE / 2.0;
 373                    let origin = point(center.x - offset.width, center.y - offset.height);
 374                    Bounds::new(origin, DEFAULT_WINDOW_SIZE)
 375                })
 376                .unwrap_or_else(|| {
 377                    Bounds::new(
 378                        point(GlobalPixels(0.0), GlobalPixels(0.0)),
 379                        DEFAULT_WINDOW_SIZE,
 380                    )
 381                })
 382        })
 383}
 384
 385impl Window {
 386    pub(crate) fn new(
 387        handle: AnyWindowHandle,
 388        options: WindowOptions,
 389        cx: &mut AppContext,
 390    ) -> Self {
 391        let WindowOptions {
 392            bounds,
 393            titlebar,
 394            focus,
 395            show,
 396            kind,
 397            is_movable,
 398            display_id,
 399            fullscreen,
 400        } = options;
 401
 402        let bounds = bounds.unwrap_or_else(|| default_bounds(cx));
 403        let platform_window = cx.platform.open_window(
 404            handle,
 405            WindowParams {
 406                bounds,
 407                titlebar,
 408                kind,
 409                is_movable,
 410                focus,
 411                show,
 412                display_id,
 413            },
 414        );
 415        let display_id = platform_window.display().id();
 416        let sprite_atlas = platform_window.sprite_atlas();
 417        let mouse_position = platform_window.mouse_position();
 418        let modifiers = platform_window.modifiers();
 419        let content_size = platform_window.content_size();
 420        let scale_factor = platform_window.scale_factor();
 421        let appearance = platform_window.appearance();
 422        let text_system = Arc::new(WindowTextSystem::new(cx.text_system().clone()));
 423        let dirty = Rc::new(Cell::new(true));
 424        let active = Rc::new(Cell::new(platform_window.is_active()));
 425        let needs_present = Rc::new(Cell::new(false));
 426        let next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>> = Default::default();
 427        let last_input_timestamp = Rc::new(Cell::new(Instant::now()));
 428
 429        if fullscreen {
 430            platform_window.toggle_fullscreen();
 431        }
 432
 433        platform_window.on_close(Box::new({
 434            let mut cx = cx.to_async();
 435            move || {
 436                let _ = handle.update(&mut cx, |_, cx| cx.remove_window());
 437            }
 438        }));
 439        platform_window.on_request_frame(Box::new({
 440            let mut cx = cx.to_async();
 441            let dirty = dirty.clone();
 442            let active = active.clone();
 443            let needs_present = needs_present.clone();
 444            let next_frame_callbacks = next_frame_callbacks.clone();
 445            let last_input_timestamp = last_input_timestamp.clone();
 446            move || {
 447                let next_frame_callbacks = next_frame_callbacks.take();
 448                if !next_frame_callbacks.is_empty() {
 449                    handle
 450                        .update(&mut cx, |_, cx| {
 451                            for callback in next_frame_callbacks {
 452                                callback(cx);
 453                            }
 454                        })
 455                        .log_err();
 456                }
 457
 458                // Keep presenting the current scene for 1 extra second since the
 459                // last input to prevent the display from underclocking the refresh rate.
 460                let needs_present = needs_present.get()
 461                    || (active.get()
 462                        && last_input_timestamp.get().elapsed() < Duration::from_secs(1));
 463
 464                if dirty.get() {
 465                    measure("frame duration", || {
 466                        handle
 467                            .update(&mut cx, |_, cx| {
 468                                cx.draw();
 469                                cx.present();
 470                            })
 471                            .log_err();
 472                    })
 473                } else if needs_present {
 474                    handle.update(&mut cx, |_, cx| cx.present()).log_err();
 475                }
 476            }
 477        }));
 478        platform_window.on_resize(Box::new({
 479            let mut cx = cx.to_async();
 480            move |_, _| {
 481                handle
 482                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 483                    .log_err();
 484            }
 485        }));
 486        platform_window.on_moved(Box::new({
 487            let mut cx = cx.to_async();
 488            move || {
 489                handle
 490                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 491                    .log_err();
 492            }
 493        }));
 494        platform_window.on_appearance_changed(Box::new({
 495            let mut cx = cx.to_async();
 496            move || {
 497                handle
 498                    .update(&mut cx, |_, cx| cx.appearance_changed())
 499                    .log_err();
 500            }
 501        }));
 502        platform_window.on_active_status_change(Box::new({
 503            let mut cx = cx.to_async();
 504            move |active| {
 505                handle
 506                    .update(&mut cx, |_, cx| {
 507                        cx.window.active.set(active);
 508                        cx.window
 509                            .activation_observers
 510                            .clone()
 511                            .retain(&(), |callback| callback(cx));
 512                        cx.refresh();
 513                    })
 514                    .log_err();
 515            }
 516        }));
 517
 518        platform_window.on_input({
 519            let mut cx = cx.to_async();
 520            Box::new(move |event| {
 521                handle
 522                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 523                    .log_err()
 524                    .unwrap_or(DispatchEventResult::default())
 525            })
 526        });
 527
 528        Window {
 529            handle,
 530            removed: false,
 531            platform_window,
 532            display_id,
 533            sprite_atlas,
 534            text_system,
 535            rem_size: px(16.),
 536            viewport_size: content_size,
 537            layout_engine: Some(TaffyLayoutEngine::new()),
 538            root_view: None,
 539            element_id_stack: GlobalElementId::default(),
 540            text_style_stack: Vec::new(),
 541            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 542            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 543            next_frame_callbacks,
 544            next_hitbox_id: HitboxId::default(),
 545            dirty_views: FxHashSet::default(),
 546            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 547            focus_listeners: SubscriberSet::new(),
 548            focus_lost_listeners: SubscriberSet::new(),
 549            default_prevented: true,
 550            mouse_position,
 551            mouse_hit_test: HitTest::default(),
 552            modifiers,
 553            scale_factor,
 554            bounds_observers: SubscriberSet::new(),
 555            appearance,
 556            appearance_observers: SubscriberSet::new(),
 557            active,
 558            dirty,
 559            needs_present,
 560            last_input_timestamp,
 561            refreshing: false,
 562            draw_phase: DrawPhase::None,
 563            activation_observers: SubscriberSet::new(),
 564            focus: None,
 565            focus_enabled: true,
 566            pending_input: None,
 567            prompt: None,
 568        }
 569    }
 570    fn new_focus_listener(
 571        &mut self,
 572        value: AnyWindowFocusListener,
 573    ) -> (Subscription, impl FnOnce()) {
 574        self.focus_listeners.insert((), value)
 575    }
 576}
 577
 578#[derive(Clone, Debug, Default, PartialEq, Eq)]
 579pub(crate) struct DispatchEventResult {
 580    pub propagate: bool,
 581    pub default_prevented: bool,
 582}
 583
 584/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 585/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 586/// to leave room to support more complex shapes in the future.
 587#[derive(Clone, Debug, Default, PartialEq, Eq)]
 588#[repr(C)]
 589pub struct ContentMask<P: Clone + Default + Debug> {
 590    /// The bounds
 591    pub bounds: Bounds<P>,
 592}
 593
 594impl ContentMask<Pixels> {
 595    /// Scale the content mask's pixel units by the given scaling factor.
 596    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 597        ContentMask {
 598            bounds: self.bounds.scale(factor),
 599        }
 600    }
 601
 602    /// Intersect the content mask with the given content mask.
 603    pub fn intersect(&self, other: &Self) -> Self {
 604        let bounds = self.bounds.intersect(&other.bounds);
 605        ContentMask { bounds }
 606    }
 607}
 608
 609/// Provides access to application state in the context of a single window. Derefs
 610/// to an [`AppContext`], so you can also pass a [`WindowContext`] to any method that takes
 611/// an [`AppContext`] and call any [`AppContext`] methods.
 612pub struct WindowContext<'a> {
 613    pub(crate) app: &'a mut AppContext,
 614    pub(crate) window: &'a mut Window,
 615}
 616
 617impl<'a> WindowContext<'a> {
 618    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 619        Self { app, window }
 620    }
 621
 622    /// Obtain a handle to the window that belongs to this context.
 623    pub fn window_handle(&self) -> AnyWindowHandle {
 624        self.window.handle
 625    }
 626
 627    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 628    pub fn refresh(&mut self) {
 629        if self.window.draw_phase == DrawPhase::None {
 630            self.window.refreshing = true;
 631            self.window.dirty.set(true);
 632        }
 633    }
 634
 635    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
 636    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
 637    pub fn notify(&mut self, view_id: EntityId) {
 638        for view_id in self
 639            .window
 640            .rendered_frame
 641            .dispatch_tree
 642            .view_path(view_id)
 643            .into_iter()
 644            .rev()
 645        {
 646            if !self.window.dirty_views.insert(view_id) {
 647                break;
 648            }
 649        }
 650
 651        if self.window.draw_phase == DrawPhase::None {
 652            self.window.dirty.set(true);
 653            self.app.push_effect(Effect::Notify { emitter: view_id });
 654        }
 655    }
 656
 657    /// Close this window.
 658    pub fn remove_window(&mut self) {
 659        self.window.removed = true;
 660    }
 661
 662    /// Obtain a new [`FocusHandle`], which allows you to track and manipulate the keyboard focus
 663    /// for elements rendered within this window.
 664    pub fn focus_handle(&mut self) -> FocusHandle {
 665        FocusHandle::new(&self.window.focus_handles)
 666    }
 667
 668    /// Obtain the currently focused [`FocusHandle`]. If no elements are focused, returns `None`.
 669    pub fn focused(&self) -> Option<FocusHandle> {
 670        self.window
 671            .focus
 672            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 673    }
 674
 675    /// Move focus to the element associated with the given [`FocusHandle`].
 676    pub fn focus(&mut self, handle: &FocusHandle) {
 677        if !self.window.focus_enabled || self.window.focus == Some(handle.id) {
 678            return;
 679        }
 680
 681        self.window.focus = Some(handle.id);
 682        self.window
 683            .rendered_frame
 684            .dispatch_tree
 685            .clear_pending_keystrokes();
 686        self.refresh();
 687    }
 688
 689    /// Remove focus from all elements within this context's window.
 690    pub fn blur(&mut self) {
 691        if !self.window.focus_enabled {
 692            return;
 693        }
 694
 695        self.window.focus = None;
 696        self.refresh();
 697    }
 698
 699    /// Blur the window and don't allow anything in it to be focused again.
 700    pub fn disable_focus(&mut self) {
 701        self.blur();
 702        self.window.focus_enabled = false;
 703    }
 704
 705    /// Accessor for the text system.
 706    pub fn text_system(&self) -> &Arc<WindowTextSystem> {
 707        &self.window.text_system
 708    }
 709
 710    /// The current text style. Which is composed of all the style refinements provided to `with_text_style`.
 711    pub fn text_style(&self) -> TextStyle {
 712        let mut style = TextStyle::default();
 713        for refinement in &self.window.text_style_stack {
 714            style.refine(refinement);
 715        }
 716        style
 717    }
 718
 719    /// Check if the platform window is maximized
 720    /// On some platforms (namely Windows) this is different than the bounds being the size of the display
 721    pub fn is_maximized(&self) -> bool {
 722        self.window.platform_window.is_maximized()
 723    }
 724
 725    /// Check if the platform window is minimized
 726    /// On some platforms (namely Windows) the position is incorrect when minimized
 727    pub fn is_minimized(&self) -> bool {
 728        self.window.platform_window.is_minimized()
 729    }
 730
 731    /// Dispatch the given action on the currently focused element.
 732    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 733        let focus_handle = self.focused();
 734
 735        let window = self.window.handle;
 736        self.app.defer(move |cx| {
 737            window
 738                .update(cx, |_, cx| {
 739                    let node_id = focus_handle
 740                        .and_then(|handle| {
 741                            cx.window
 742                                .rendered_frame
 743                                .dispatch_tree
 744                                .focusable_node_id(handle.id)
 745                        })
 746                        .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 747
 748                    cx.dispatch_action_on_node(node_id, action.as_ref());
 749                })
 750                .log_err();
 751        })
 752    }
 753
 754    pub(crate) fn dispatch_keystroke_observers(
 755        &mut self,
 756        event: &dyn Any,
 757        action: Option<Box<dyn Action>>,
 758    ) {
 759        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 760            return;
 761        };
 762
 763        self.keystroke_observers
 764            .clone()
 765            .retain(&(), move |callback| {
 766                (callback)(
 767                    &KeystrokeEvent {
 768                        keystroke: key_down_event.keystroke.clone(),
 769                        action: action.as_ref().map(|action| action.boxed_clone()),
 770                    },
 771                    self,
 772                );
 773                true
 774            });
 775    }
 776
 777    pub(crate) fn clear_pending_keystrokes(&mut self) {
 778        self.window
 779            .rendered_frame
 780            .dispatch_tree
 781            .clear_pending_keystrokes();
 782        self.window
 783            .next_frame
 784            .dispatch_tree
 785            .clear_pending_keystrokes();
 786    }
 787
 788    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 789    /// that are currently on the stack to be returned to the app.
 790    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 791        let handle = self.window.handle;
 792        self.app.defer(move |cx| {
 793            handle.update(cx, |_, cx| f(cx)).ok();
 794        });
 795    }
 796
 797    /// Subscribe to events emitted by a model or view.
 798    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
 799    /// 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.
 800    pub fn subscribe<Emitter, E, Evt>(
 801        &mut self,
 802        entity: &E,
 803        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 804    ) -> Subscription
 805    where
 806        Emitter: EventEmitter<Evt>,
 807        E: Entity<Emitter>,
 808        Evt: 'static,
 809    {
 810        let entity_id = entity.entity_id();
 811        let entity = entity.downgrade();
 812        let window_handle = self.window.handle;
 813        self.app.new_subscription(
 814            entity_id,
 815            (
 816                TypeId::of::<Evt>(),
 817                Box::new(move |event, cx| {
 818                    window_handle
 819                        .update(cx, |_, cx| {
 820                            if let Some(handle) = E::upgrade_from(&entity) {
 821                                let event = event.downcast_ref().expect("invalid event type");
 822                                on_event(handle, event, cx);
 823                                true
 824                            } else {
 825                                false
 826                            }
 827                        })
 828                        .unwrap_or(false)
 829                }),
 830            ),
 831        )
 832    }
 833
 834    /// Creates an [`AsyncWindowContext`], which has a static lifetime and can be held across
 835    /// await points in async code.
 836    pub fn to_async(&self) -> AsyncWindowContext {
 837        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 838    }
 839
 840    /// Schedule the given closure to be run directly after the current frame is rendered.
 841    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 842        RefCell::borrow_mut(&self.window.next_frame_callbacks).push(Box::new(callback));
 843    }
 844
 845    /// Spawn the future returned by the given closure on the application thread pool.
 846    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 847    /// use within your future.
 848    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 849    where
 850        R: 'static,
 851        Fut: Future<Output = R> + 'static,
 852    {
 853        self.app
 854            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 855    }
 856
 857    /// Updates the global of the given type. The given closure is given simultaneous mutable
 858    /// access both to the global and the context.
 859    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 860    where
 861        G: Global,
 862    {
 863        let mut global = self.app.lease_global::<G>();
 864        let result = f(&mut global, self);
 865        self.app.end_global_lease(global);
 866        result
 867    }
 868
 869    fn window_bounds_changed(&mut self) {
 870        self.window.scale_factor = self.window.platform_window.scale_factor();
 871        self.window.viewport_size = self.window.platform_window.content_size();
 872        self.window.display_id = self.window.platform_window.display().id();
 873        self.refresh();
 874
 875        self.window
 876            .bounds_observers
 877            .clone()
 878            .retain(&(), |callback| callback(self));
 879    }
 880
 881    /// Returns the bounds of the current window in the global coordinate space, which could span across multiple displays.
 882    pub fn window_bounds(&self) -> Bounds<GlobalPixels> {
 883        self.window.platform_window.bounds()
 884    }
 885
 886    /// Retusn whether or not the window is currently fullscreen
 887    pub fn is_fullscreen(&self) -> bool {
 888        self.window.platform_window.is_fullscreen()
 889    }
 890
 891    fn appearance_changed(&mut self) {
 892        self.window.appearance = self.window.platform_window.appearance();
 893
 894        self.window
 895            .appearance_observers
 896            .clone()
 897            .retain(&(), |callback| callback(self));
 898    }
 899
 900    /// Returns the appearance of the current window.
 901    pub fn appearance(&self) -> WindowAppearance {
 902        self.window.appearance
 903    }
 904
 905    /// Returns the size of the drawable area within the window.
 906    pub fn viewport_size(&self) -> Size<Pixels> {
 907        self.window.viewport_size
 908    }
 909
 910    /// Returns whether this window is focused by the operating system (receiving key events).
 911    pub fn is_window_active(&self) -> bool {
 912        self.window.active.get()
 913    }
 914
 915    /// Toggle zoom on the window.
 916    pub fn zoom_window(&self) {
 917        self.window.platform_window.zoom();
 918    }
 919
 920    /// Updates the window's title at the platform level.
 921    pub fn set_window_title(&mut self, title: &str) {
 922        self.window.platform_window.set_title(title);
 923    }
 924
 925    /// Mark the window as dirty at the platform level.
 926    pub fn set_window_edited(&mut self, edited: bool) {
 927        self.window.platform_window.set_edited(edited);
 928    }
 929
 930    /// Determine the display on which the window is visible.
 931    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 932        self.platform
 933            .displays()
 934            .into_iter()
 935            .find(|display| display.id() == self.window.display_id)
 936    }
 937
 938    /// Show the platform character palette.
 939    pub fn show_character_palette(&self) {
 940        self.window.platform_window.show_character_palette();
 941    }
 942
 943    /// The scale factor of the display associated with the window. For example, it could
 944    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 945    /// be rendered as two pixels on screen.
 946    pub fn scale_factor(&self) -> f32 {
 947        self.window.scale_factor
 948    }
 949
 950    /// The size of an em for the base font of the application. Adjusting this value allows the
 951    /// UI to scale, just like zooming a web page.
 952    pub fn rem_size(&self) -> Pixels {
 953        self.window.rem_size
 954    }
 955
 956    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 957    /// UI to scale, just like zooming a web page.
 958    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 959        self.window.rem_size = rem_size.into();
 960    }
 961
 962    /// The line height associated with the current text style.
 963    pub fn line_height(&self) -> Pixels {
 964        let rem_size = self.rem_size();
 965        let text_style = self.text_style();
 966        text_style
 967            .line_height
 968            .to_pixels(text_style.font_size, rem_size)
 969    }
 970
 971    /// Call to prevent the default action of an event. Currently only used to prevent
 972    /// parent elements from becoming focused on mouse down.
 973    pub fn prevent_default(&mut self) {
 974        self.window.default_prevented = true;
 975    }
 976
 977    /// Obtain whether default has been prevented for the event currently being dispatched.
 978    pub fn default_prevented(&self) -> bool {
 979        self.window.default_prevented
 980    }
 981
 982    /// Determine whether the given action is available along the dispatch path to the currently focused element.
 983    pub fn is_action_available(&self, action: &dyn Action) -> bool {
 984        let target = self
 985            .focused()
 986            .and_then(|focused_handle| {
 987                self.window
 988                    .rendered_frame
 989                    .dispatch_tree
 990                    .focusable_node_id(focused_handle.id)
 991            })
 992            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
 993        self.window
 994            .rendered_frame
 995            .dispatch_tree
 996            .is_action_available(action, target)
 997    }
 998
 999    /// The position of the mouse relative to the window.
1000    pub fn mouse_position(&self) -> Point<Pixels> {
1001        self.window.mouse_position
1002    }
1003
1004    /// The current state of the keyboard's modifiers
1005    pub fn modifiers(&self) -> Modifiers {
1006        self.window.modifiers
1007    }
1008
1009    /// Produces a new frame and assigns it to `rendered_frame`. To actually show
1010    /// the contents of the new [Scene], use [present].
1011    #[profiling::function]
1012    pub fn draw(&mut self) {
1013        self.window.dirty.set(false);
1014
1015        // Restore the previously-used input handler.
1016        if let Some(input_handler) = self.window.platform_window.take_input_handler() {
1017            self.window
1018                .rendered_frame
1019                .input_handlers
1020                .push(Some(input_handler));
1021        }
1022
1023        self.with_element_context(|cx| cx.draw_roots());
1024        self.window.dirty_views.clear();
1025
1026        self.window
1027            .next_frame
1028            .dispatch_tree
1029            .preserve_pending_keystrokes(
1030                &mut self.window.rendered_frame.dispatch_tree,
1031                self.window.focus,
1032            );
1033        self.window.next_frame.focus = self.window.focus;
1034        self.window.next_frame.window_active = self.window.active.get();
1035
1036        // Register requested input handler with the platform window.
1037        if let Some(input_handler) = self.window.next_frame.input_handlers.pop() {
1038            self.window
1039                .platform_window
1040                .set_input_handler(input_handler.unwrap());
1041        }
1042
1043        self.window.layout_engine.as_mut().unwrap().clear();
1044        self.text_system().finish_frame();
1045        self.window
1046            .next_frame
1047            .finish(&mut self.window.rendered_frame);
1048        ELEMENT_ARENA.with_borrow_mut(|element_arena| {
1049            let percentage = (element_arena.len() as f32 / element_arena.capacity() as f32) * 100.;
1050            if percentage >= 80. {
1051                log::warn!("elevated element arena occupation: {}.", percentage);
1052            }
1053            element_arena.clear();
1054        });
1055
1056        self.window.draw_phase = DrawPhase::Focus;
1057        let previous_focus_path = self.window.rendered_frame.focus_path();
1058        let previous_window_active = self.window.rendered_frame.window_active;
1059        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1060        self.window.next_frame.clear();
1061        let current_focus_path = self.window.rendered_frame.focus_path();
1062        let current_window_active = self.window.rendered_frame.window_active;
1063
1064        if previous_focus_path != current_focus_path
1065            || previous_window_active != current_window_active
1066        {
1067            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1068                self.window
1069                    .focus_lost_listeners
1070                    .clone()
1071                    .retain(&(), |listener| listener(self));
1072            }
1073
1074            let event = FocusEvent {
1075                previous_focus_path: if previous_window_active {
1076                    previous_focus_path
1077                } else {
1078                    Default::default()
1079                },
1080                current_focus_path: if current_window_active {
1081                    current_focus_path
1082                } else {
1083                    Default::default()
1084                },
1085            };
1086            self.window
1087                .focus_listeners
1088                .clone()
1089                .retain(&(), |listener| listener(&event, self));
1090        }
1091
1092        self.reset_cursor_style();
1093        self.window.refreshing = false;
1094        self.window.draw_phase = DrawPhase::None;
1095        self.window.needs_present.set(true);
1096    }
1097
1098    #[profiling::function]
1099    fn present(&self) {
1100        self.window
1101            .platform_window
1102            .draw(&self.window.rendered_frame.scene);
1103        self.window.needs_present.set(false);
1104        profiling::finish_frame!();
1105    }
1106
1107    fn reset_cursor_style(&self) {
1108        // Set the cursor only if we're the active window.
1109        if self.is_window_active() {
1110            let style = self
1111                .window
1112                .rendered_frame
1113                .cursor_styles
1114                .iter()
1115                .rev()
1116                .find(|request| request.hitbox_id.is_hovered(self))
1117                .map(|request| request.style)
1118                .unwrap_or(CursorStyle::Arrow);
1119            self.platform.set_cursor_style(style);
1120        }
1121    }
1122
1123    /// Dispatch a given keystroke as though the user had typed it.
1124    /// You can create a keystroke with Keystroke::parse("").
1125    pub fn dispatch_keystroke(&mut self, keystroke: Keystroke) -> bool {
1126        let keystroke = keystroke.with_simulated_ime();
1127        let result = self.dispatch_event(PlatformInput::KeyDown(KeyDownEvent {
1128            keystroke: keystroke.clone(),
1129            is_held: false,
1130        }));
1131        if !result.propagate {
1132            return true;
1133        }
1134
1135        if let Some(input) = keystroke.ime_key {
1136            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1137                input_handler.dispatch_input(&input, self);
1138                self.window.platform_window.set_input_handler(input_handler);
1139                return true;
1140            }
1141        }
1142
1143        false
1144    }
1145
1146    /// Represent this action as a key binding string, to display in the UI.
1147    pub fn keystroke_text_for(&self, action: &dyn Action) -> String {
1148        self.bindings_for_action(action)
1149            .into_iter()
1150            .next()
1151            .map(|binding| {
1152                binding
1153                    .keystrokes()
1154                    .iter()
1155                    .map(ToString::to_string)
1156                    .collect::<Vec<_>>()
1157                    .join(" ")
1158            })
1159            .unwrap_or_else(|| action.name().to_string())
1160    }
1161
1162    /// Dispatch a mouse or keyboard event on the window.
1163    #[profiling::function]
1164    pub fn dispatch_event(&mut self, event: PlatformInput) -> DispatchEventResult {
1165        self.window.last_input_timestamp.set(Instant::now());
1166        // Handlers may set this to false by calling `stop_propagation`.
1167        self.app.propagate_event = true;
1168        // Handlers may set this to true by calling `prevent_default`.
1169        self.window.default_prevented = false;
1170
1171        let event = match event {
1172            // Track the mouse position with our own state, since accessing the platform
1173            // API for the mouse position can only occur on the main thread.
1174            PlatformInput::MouseMove(mouse_move) => {
1175                self.window.mouse_position = mouse_move.position;
1176                self.window.modifiers = mouse_move.modifiers;
1177                PlatformInput::MouseMove(mouse_move)
1178            }
1179            PlatformInput::MouseDown(mouse_down) => {
1180                self.window.mouse_position = mouse_down.position;
1181                self.window.modifiers = mouse_down.modifiers;
1182                PlatformInput::MouseDown(mouse_down)
1183            }
1184            PlatformInput::MouseUp(mouse_up) => {
1185                self.window.mouse_position = mouse_up.position;
1186                self.window.modifiers = mouse_up.modifiers;
1187                PlatformInput::MouseUp(mouse_up)
1188            }
1189            PlatformInput::MouseExited(mouse_exited) => {
1190                self.window.modifiers = mouse_exited.modifiers;
1191                PlatformInput::MouseExited(mouse_exited)
1192            }
1193            PlatformInput::ModifiersChanged(modifiers_changed) => {
1194                self.window.modifiers = modifiers_changed.modifiers;
1195                PlatformInput::ModifiersChanged(modifiers_changed)
1196            }
1197            PlatformInput::ScrollWheel(scroll_wheel) => {
1198                self.window.mouse_position = scroll_wheel.position;
1199                self.window.modifiers = scroll_wheel.modifiers;
1200                PlatformInput::ScrollWheel(scroll_wheel)
1201            }
1202            // Translate dragging and dropping of external files from the operating system
1203            // to internal drag and drop events.
1204            PlatformInput::FileDrop(file_drop) => match file_drop {
1205                FileDropEvent::Entered { position, paths } => {
1206                    self.window.mouse_position = position;
1207                    if self.active_drag.is_none() {
1208                        self.active_drag = Some(AnyDrag {
1209                            value: Box::new(paths.clone()),
1210                            view: self.new_view(|_| paths).into(),
1211                            cursor_offset: position,
1212                        });
1213                    }
1214                    PlatformInput::MouseMove(MouseMoveEvent {
1215                        position,
1216                        pressed_button: Some(MouseButton::Left),
1217                        modifiers: Modifiers::default(),
1218                    })
1219                }
1220                FileDropEvent::Pending { position } => {
1221                    self.window.mouse_position = position;
1222                    PlatformInput::MouseMove(MouseMoveEvent {
1223                        position,
1224                        pressed_button: Some(MouseButton::Left),
1225                        modifiers: Modifiers::default(),
1226                    })
1227                }
1228                FileDropEvent::Submit { position } => {
1229                    self.activate(true);
1230                    self.window.mouse_position = position;
1231                    PlatformInput::MouseUp(MouseUpEvent {
1232                        button: MouseButton::Left,
1233                        position,
1234                        modifiers: Modifiers::default(),
1235                        click_count: 1,
1236                    })
1237                }
1238                FileDropEvent::Exited => {
1239                    self.active_drag.take();
1240                    PlatformInput::FileDrop(FileDropEvent::Exited)
1241                }
1242            },
1243            PlatformInput::KeyDown(_) | PlatformInput::KeyUp(_) => event,
1244        };
1245
1246        if let Some(any_mouse_event) = event.mouse_event() {
1247            self.dispatch_mouse_event(any_mouse_event);
1248        } else if let Some(any_key_event) = event.keyboard_event() {
1249            self.dispatch_key_event(any_key_event);
1250        }
1251
1252        DispatchEventResult {
1253            propagate: self.app.propagate_event,
1254            default_prevented: self.window.default_prevented,
1255        }
1256    }
1257
1258    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1259        let hit_test = self.window.rendered_frame.hit_test(self.mouse_position());
1260        if hit_test != self.window.mouse_hit_test {
1261            self.window.mouse_hit_test = hit_test;
1262            self.reset_cursor_style();
1263        }
1264
1265        let mut mouse_listeners = mem::take(&mut self.window.rendered_frame.mouse_listeners);
1266        self.with_element_context(|cx| {
1267            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1268            // special purposes, such as detecting events outside of a given Bounds.
1269            for listener in &mut mouse_listeners {
1270                let listener = listener.as_mut().unwrap();
1271                listener(event, DispatchPhase::Capture, cx);
1272                if !cx.app.propagate_event {
1273                    break;
1274                }
1275            }
1276
1277            // Bubble phase, where most normal handlers do their work.
1278            if cx.app.propagate_event {
1279                for listener in mouse_listeners.iter_mut().rev() {
1280                    let listener = listener.as_mut().unwrap();
1281                    listener(event, DispatchPhase::Bubble, cx);
1282                    if !cx.app.propagate_event {
1283                        break;
1284                    }
1285                }
1286            }
1287        });
1288        self.window.rendered_frame.mouse_listeners = mouse_listeners;
1289
1290        if self.app.propagate_event && self.has_active_drag() {
1291            if event.is::<MouseMoveEvent>() {
1292                // If this was a mouse move event, redraw the window so that the
1293                // active drag can follow the mouse cursor.
1294                self.refresh();
1295            } else if event.is::<MouseUpEvent>() {
1296                // If this was a mouse up event, cancel the active drag and redraw
1297                // the window.
1298                self.active_drag = None;
1299                self.refresh();
1300            }
1301        }
1302    }
1303
1304    fn dispatch_key_event(&mut self, event: &dyn Any) {
1305        if self.window.dirty.get() {
1306            self.draw();
1307        }
1308
1309        let node_id = self
1310            .window
1311            .focus
1312            .and_then(|focus_id| {
1313                self.window
1314                    .rendered_frame
1315                    .dispatch_tree
1316                    .focusable_node_id(focus_id)
1317            })
1318            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1319
1320        let dispatch_path = self
1321            .window
1322            .rendered_frame
1323            .dispatch_tree
1324            .dispatch_path(node_id);
1325
1326        if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1327            let KeymatchResult { bindings, pending } = self
1328                .window
1329                .rendered_frame
1330                .dispatch_tree
1331                .dispatch_key(&key_down_event.keystroke, &dispatch_path);
1332
1333            if pending {
1334                let mut currently_pending = self.window.pending_input.take().unwrap_or_default();
1335                if currently_pending.focus.is_some() && currently_pending.focus != self.window.focus
1336                {
1337                    currently_pending = PendingInput::default();
1338                }
1339                currently_pending.focus = self.window.focus;
1340                currently_pending
1341                    .keystrokes
1342                    .push(key_down_event.keystroke.clone());
1343                for binding in bindings {
1344                    currently_pending.bindings.push(binding);
1345                }
1346
1347                currently_pending.timer = Some(self.spawn(|mut cx| async move {
1348                    cx.background_executor.timer(Duration::from_secs(1)).await;
1349                    cx.update(move |cx| {
1350                        cx.clear_pending_keystrokes();
1351                        let Some(currently_pending) = cx.window.pending_input.take() else {
1352                            return;
1353                        };
1354                        cx.replay_pending_input(currently_pending)
1355                    })
1356                    .log_err();
1357                }));
1358
1359                self.window.pending_input = Some(currently_pending);
1360
1361                self.propagate_event = false;
1362                return;
1363            } else if let Some(currently_pending) = self.window.pending_input.take() {
1364                if bindings
1365                    .iter()
1366                    .all(|binding| !currently_pending.used_by_binding(binding))
1367                {
1368                    self.replay_pending_input(currently_pending)
1369                }
1370            }
1371
1372            if !bindings.is_empty() {
1373                self.clear_pending_keystrokes();
1374            }
1375
1376            self.propagate_event = true;
1377            for binding in bindings {
1378                self.dispatch_action_on_node(node_id, binding.action.as_ref());
1379                if !self.propagate_event {
1380                    self.dispatch_keystroke_observers(event, Some(binding.action));
1381                    return;
1382                }
1383            }
1384        }
1385
1386        self.dispatch_key_down_up_event(event, &dispatch_path);
1387        if !self.propagate_event {
1388            return;
1389        }
1390
1391        self.dispatch_modifiers_changed_event(event, &dispatch_path);
1392        if !self.propagate_event {
1393            return;
1394        }
1395
1396        self.dispatch_keystroke_observers(event, None);
1397    }
1398
1399    fn dispatch_key_down_up_event(
1400        &mut self,
1401        event: &dyn Any,
1402        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1403    ) {
1404        // Capture phase
1405        for node_id in dispatch_path {
1406            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1407
1408            for key_listener in node.key_listeners.clone() {
1409                self.with_element_context(|cx| {
1410                    key_listener(event, DispatchPhase::Capture, cx);
1411                });
1412                if !self.propagate_event {
1413                    return;
1414                }
1415            }
1416        }
1417
1418        // Bubble phase
1419        for node_id in dispatch_path.iter().rev() {
1420            // Handle low level key events
1421            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1422            for key_listener in node.key_listeners.clone() {
1423                self.with_element_context(|cx| {
1424                    key_listener(event, DispatchPhase::Bubble, cx);
1425                });
1426                if !self.propagate_event {
1427                    return;
1428                }
1429            }
1430        }
1431    }
1432
1433    fn dispatch_modifiers_changed_event(
1434        &mut self,
1435        event: &dyn Any,
1436        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1437    ) {
1438        let Some(event) = event.downcast_ref::<ModifiersChangedEvent>() else {
1439            return;
1440        };
1441        for node_id in dispatch_path.iter().rev() {
1442            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1443            for listener in node.modifiers_changed_listeners.clone() {
1444                self.with_element_context(|cx| {
1445                    listener(event, cx);
1446                });
1447                if !self.propagate_event {
1448                    return;
1449                }
1450            }
1451        }
1452    }
1453
1454    /// Determine whether a potential multi-stroke key binding is in progress on this window.
1455    pub fn has_pending_keystrokes(&self) -> bool {
1456        self.window
1457            .rendered_frame
1458            .dispatch_tree
1459            .has_pending_keystrokes()
1460    }
1461
1462    fn replay_pending_input(&mut self, currently_pending: PendingInput) {
1463        let node_id = self
1464            .window
1465            .focus
1466            .and_then(|focus_id| {
1467                self.window
1468                    .rendered_frame
1469                    .dispatch_tree
1470                    .focusable_node_id(focus_id)
1471            })
1472            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1473
1474        if self.window.focus != currently_pending.focus {
1475            return;
1476        }
1477
1478        let input = currently_pending.input();
1479
1480        self.propagate_event = true;
1481        for binding in currently_pending.bindings {
1482            self.dispatch_action_on_node(node_id, binding.action.as_ref());
1483            if !self.propagate_event {
1484                return;
1485            }
1486        }
1487
1488        let dispatch_path = self
1489            .window
1490            .rendered_frame
1491            .dispatch_tree
1492            .dispatch_path(node_id);
1493
1494        for keystroke in currently_pending.keystrokes {
1495            let event = KeyDownEvent {
1496                keystroke,
1497                is_held: false,
1498            };
1499
1500            self.dispatch_key_down_up_event(&event, &dispatch_path);
1501            if !self.propagate_event {
1502                return;
1503            }
1504        }
1505
1506        if !input.is_empty() {
1507            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1508                input_handler.dispatch_input(&input, self);
1509                self.window.platform_window.set_input_handler(input_handler)
1510            }
1511        }
1512    }
1513
1514    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: &dyn Action) {
1515        let dispatch_path = self
1516            .window
1517            .rendered_frame
1518            .dispatch_tree
1519            .dispatch_path(node_id);
1520
1521        // Capture phase for global actions.
1522        self.propagate_event = true;
1523        if let Some(mut global_listeners) = self
1524            .global_action_listeners
1525            .remove(&action.as_any().type_id())
1526        {
1527            for listener in &global_listeners {
1528                listener(action.as_any(), DispatchPhase::Capture, self);
1529                if !self.propagate_event {
1530                    break;
1531                }
1532            }
1533
1534            global_listeners.extend(
1535                self.global_action_listeners
1536                    .remove(&action.as_any().type_id())
1537                    .unwrap_or_default(),
1538            );
1539
1540            self.global_action_listeners
1541                .insert(action.as_any().type_id(), global_listeners);
1542        }
1543
1544        if !self.propagate_event {
1545            return;
1546        }
1547
1548        // Capture phase for window actions.
1549        for node_id in &dispatch_path {
1550            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1551            for DispatchActionListener {
1552                action_type,
1553                listener,
1554            } in node.action_listeners.clone()
1555            {
1556                let any_action = action.as_any();
1557                if action_type == any_action.type_id() {
1558                    self.with_element_context(|cx| {
1559                        listener(any_action, DispatchPhase::Capture, cx);
1560                    });
1561
1562                    if !self.propagate_event {
1563                        return;
1564                    }
1565                }
1566            }
1567        }
1568
1569        // Bubble phase for window actions.
1570        for node_id in dispatch_path.iter().rev() {
1571            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1572            for DispatchActionListener {
1573                action_type,
1574                listener,
1575            } in node.action_listeners.clone()
1576            {
1577                let any_action = action.as_any();
1578                if action_type == any_action.type_id() {
1579                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1580
1581                    self.with_element_context(|cx| {
1582                        listener(any_action, DispatchPhase::Bubble, cx);
1583                    });
1584
1585                    if !self.propagate_event {
1586                        return;
1587                    }
1588                }
1589            }
1590        }
1591
1592        // Bubble phase for global actions.
1593        if let Some(mut global_listeners) = self
1594            .global_action_listeners
1595            .remove(&action.as_any().type_id())
1596        {
1597            for listener in global_listeners.iter().rev() {
1598                self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1599
1600                listener(action.as_any(), DispatchPhase::Bubble, self);
1601                if !self.propagate_event {
1602                    break;
1603                }
1604            }
1605
1606            global_listeners.extend(
1607                self.global_action_listeners
1608                    .remove(&action.as_any().type_id())
1609                    .unwrap_or_default(),
1610            );
1611
1612            self.global_action_listeners
1613                .insert(action.as_any().type_id(), global_listeners);
1614        }
1615    }
1616
1617    /// Register the given handler to be invoked whenever the global of the given type
1618    /// is updated.
1619    pub fn observe_global<G: Global>(
1620        &mut self,
1621        f: impl Fn(&mut WindowContext<'_>) + 'static,
1622    ) -> Subscription {
1623        let window_handle = self.window.handle;
1624        let (subscription, activate) = self.global_observers.insert(
1625            TypeId::of::<G>(),
1626            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1627        );
1628        self.app.defer(move |_| activate());
1629        subscription
1630    }
1631
1632    /// Focus the current window and bring it to the foreground at the platform level.
1633    pub fn activate_window(&self) {
1634        self.window.platform_window.activate();
1635    }
1636
1637    /// Minimize the current window at the platform level.
1638    pub fn minimize_window(&self) {
1639        self.window.platform_window.minimize();
1640    }
1641
1642    /// Toggle full screen status on the current window at the platform level.
1643    pub fn toggle_fullscreen(&self) {
1644        self.window.platform_window.toggle_fullscreen();
1645    }
1646
1647    /// Present a platform dialog.
1648    /// The provided message will be presented, along with buttons for each answer.
1649    /// When a button is clicked, the returned Receiver will receive the index of the clicked button.
1650    pub fn prompt(
1651        &mut self,
1652        level: PromptLevel,
1653        message: &str,
1654        detail: Option<&str>,
1655        answers: &[&str],
1656    ) -> oneshot::Receiver<usize> {
1657        let prompt_builder = self.app.prompt_builder.take();
1658        let Some(prompt_builder) = prompt_builder else {
1659            unreachable!("Re-entrant window prompting is not supported by GPUI");
1660        };
1661
1662        let receiver = match &prompt_builder {
1663            PromptBuilder::Default => self
1664                .window
1665                .platform_window
1666                .prompt(level, message, detail, answers)
1667                .unwrap_or_else(|| {
1668                    self.build_custom_prompt(&prompt_builder, level, message, detail, answers)
1669                }),
1670            PromptBuilder::Custom(_) => {
1671                self.build_custom_prompt(&prompt_builder, level, message, detail, answers)
1672            }
1673        };
1674
1675        self.app.prompt_builder = Some(prompt_builder);
1676
1677        receiver
1678    }
1679
1680    fn build_custom_prompt(
1681        &mut self,
1682        prompt_builder: &PromptBuilder,
1683        level: PromptLevel,
1684        message: &str,
1685        detail: Option<&str>,
1686        answers: &[&str],
1687    ) -> oneshot::Receiver<usize> {
1688        let (sender, receiver) = oneshot::channel();
1689        let handle = PromptHandle::new(sender);
1690        let handle = (prompt_builder)(level, message, detail, answers, handle, self);
1691        self.window.prompt = Some(handle);
1692        receiver
1693    }
1694
1695    /// Returns all available actions for the focused element.
1696    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1697        let node_id = self
1698            .window
1699            .focus
1700            .and_then(|focus_id| {
1701                self.window
1702                    .rendered_frame
1703                    .dispatch_tree
1704                    .focusable_node_id(focus_id)
1705            })
1706            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1707
1708        let mut actions = self
1709            .window
1710            .rendered_frame
1711            .dispatch_tree
1712            .available_actions(node_id);
1713        for action_type in self.global_action_listeners.keys() {
1714            if let Err(ix) = actions.binary_search_by_key(action_type, |a| a.as_any().type_id()) {
1715                let action = self.actions.build_action_type(action_type).ok();
1716                if let Some(action) = action {
1717                    actions.insert(ix, action);
1718                }
1719            }
1720        }
1721        actions
1722    }
1723
1724    /// Returns key bindings that invoke the given action on the currently focused element.
1725    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1726        self.window
1727            .rendered_frame
1728            .dispatch_tree
1729            .bindings_for_action(
1730                action,
1731                &self.window.rendered_frame.dispatch_tree.context_stack,
1732            )
1733    }
1734
1735    /// Returns any bindings that would invoke the given action on the given focus handle if it were focused.
1736    pub fn bindings_for_action_in(
1737        &self,
1738        action: &dyn Action,
1739        focus_handle: &FocusHandle,
1740    ) -> Vec<KeyBinding> {
1741        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1742
1743        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1744            return vec![];
1745        };
1746        let context_stack: Vec<_> = dispatch_tree
1747            .dispatch_path(node_id)
1748            .into_iter()
1749            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1750            .collect();
1751        dispatch_tree.bindings_for_action(action, &context_stack)
1752    }
1753
1754    /// Returns a generic event listener that invokes the given listener with the view and context associated with the given view handle.
1755    pub fn listener_for<V: Render, E>(
1756        &self,
1757        view: &View<V>,
1758        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1759    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1760        let view = view.downgrade();
1761        move |e: &E, cx: &mut WindowContext| {
1762            view.update(cx, |view, cx| f(view, e, cx)).ok();
1763        }
1764    }
1765
1766    /// Returns a generic handler that invokes the given handler with the view and context associated with the given view handle.
1767    pub fn handler_for<V: Render>(
1768        &self,
1769        view: &View<V>,
1770        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1771    ) -> impl Fn(&mut WindowContext) {
1772        let view = view.downgrade();
1773        move |cx: &mut WindowContext| {
1774            view.update(cx, |view, cx| f(view, cx)).ok();
1775        }
1776    }
1777
1778    /// Register a callback that can interrupt the closing of the current window based the returned boolean.
1779    /// If the callback returns false, the window won't be closed.
1780    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1781        let mut this = self.to_async();
1782        self.window
1783            .platform_window
1784            .on_should_close(Box::new(move || this.update(|cx| f(cx)).unwrap_or(true)))
1785    }
1786
1787    /// Register an action listener on the window for the next frame. The type of action
1788    /// is determined by the first parameter of the given listener. When the next frame is rendered
1789    /// the listener will be cleared.
1790    ///
1791    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
1792    /// a specific need to register a global listener.
1793    pub fn on_action(
1794        &mut self,
1795        action_type: TypeId,
1796        listener: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
1797    ) {
1798        self.window
1799            .next_frame
1800            .dispatch_tree
1801            .on_action(action_type, Rc::new(listener));
1802    }
1803}
1804
1805#[cfg(target_os = "windows")]
1806impl WindowContext<'_> {
1807    /// Returns the raw HWND handle for the window.
1808    pub fn get_raw_handle(&self) -> windows::Win32::Foundation::HWND {
1809        self.window.platform_window.get_raw_handle()
1810    }
1811}
1812
1813impl Context for WindowContext<'_> {
1814    type Result<T> = T;
1815
1816    fn new_model<T>(&mut self, build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T) -> Model<T>
1817    where
1818        T: 'static,
1819    {
1820        let slot = self.app.entities.reserve();
1821        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1822        self.entities.insert(slot, model)
1823    }
1824
1825    fn update_model<T: 'static, R>(
1826        &mut self,
1827        model: &Model<T>,
1828        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1829    ) -> R {
1830        let mut entity = self.entities.lease(model);
1831        let result = update(
1832            &mut *entity,
1833            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1834        );
1835        self.entities.end_lease(entity);
1836        result
1837    }
1838
1839    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1840    where
1841        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1842    {
1843        if window == self.window.handle {
1844            let root_view = self.window.root_view.clone().unwrap();
1845            Ok(update(root_view, self))
1846        } else {
1847            window.update(self.app, update)
1848        }
1849    }
1850
1851    fn read_model<T, R>(
1852        &self,
1853        handle: &Model<T>,
1854        read: impl FnOnce(&T, &AppContext) -> R,
1855    ) -> Self::Result<R>
1856    where
1857        T: 'static,
1858    {
1859        let entity = self.entities.read(handle);
1860        read(entity, &*self.app)
1861    }
1862
1863    fn read_window<T, R>(
1864        &self,
1865        window: &WindowHandle<T>,
1866        read: impl FnOnce(View<T>, &AppContext) -> R,
1867    ) -> Result<R>
1868    where
1869        T: 'static,
1870    {
1871        if window.any_handle == self.window.handle {
1872            let root_view = self
1873                .window
1874                .root_view
1875                .clone()
1876                .unwrap()
1877                .downcast::<T>()
1878                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1879            Ok(read(root_view, self))
1880        } else {
1881            self.app.read_window(window, read)
1882        }
1883    }
1884}
1885
1886impl VisualContext for WindowContext<'_> {
1887    fn new_view<V>(
1888        &mut self,
1889        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1890    ) -> Self::Result<View<V>>
1891    where
1892        V: 'static + Render,
1893    {
1894        let slot = self.app.entities.reserve();
1895        let view = View {
1896            model: slot.clone(),
1897        };
1898        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1899        let entity = build_view_state(&mut cx);
1900        cx.entities.insert(slot, entity);
1901
1902        // Non-generic part to avoid leaking SubscriberSet to invokers of `new_view`.
1903        fn notify_observers(cx: &mut WindowContext, tid: TypeId, view: AnyView) {
1904            cx.new_view_observers.clone().retain(&tid, |observer| {
1905                let any_view = view.clone();
1906                (observer)(any_view, cx);
1907                true
1908            });
1909        }
1910        notify_observers(self, TypeId::of::<V>(), AnyView::from(view.clone()));
1911
1912        view
1913    }
1914
1915    /// Updates the given view. Prefer calling [`View::update`] instead, which calls this method.
1916    fn update_view<T: 'static, R>(
1917        &mut self,
1918        view: &View<T>,
1919        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1920    ) -> Self::Result<R> {
1921        let mut lease = self.app.entities.lease(&view.model);
1922        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, view);
1923        let result = update(&mut *lease, &mut cx);
1924        cx.app.entities.end_lease(lease);
1925        result
1926    }
1927
1928    fn replace_root_view<V>(
1929        &mut self,
1930        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1931    ) -> Self::Result<View<V>>
1932    where
1933        V: 'static + Render,
1934    {
1935        let view = self.new_view(build_view);
1936        self.window.root_view = Some(view.clone().into());
1937        self.refresh();
1938        view
1939    }
1940
1941    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1942        self.update_view(view, |view, cx| {
1943            view.focus_handle(cx).clone().focus(cx);
1944        })
1945    }
1946
1947    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1948    where
1949        V: ManagedView,
1950    {
1951        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1952    }
1953}
1954
1955impl<'a> std::ops::Deref for WindowContext<'a> {
1956    type Target = AppContext;
1957
1958    fn deref(&self) -> &Self::Target {
1959        self.app
1960    }
1961}
1962
1963impl<'a> std::ops::DerefMut for WindowContext<'a> {
1964    fn deref_mut(&mut self) -> &mut Self::Target {
1965        self.app
1966    }
1967}
1968
1969impl<'a> Borrow<AppContext> for WindowContext<'a> {
1970    fn borrow(&self) -> &AppContext {
1971        self.app
1972    }
1973}
1974
1975impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1976    fn borrow_mut(&mut self) -> &mut AppContext {
1977        self.app
1978    }
1979}
1980
1981/// This trait contains functionality that is shared across [`ViewContext`] and [`WindowContext`]
1982pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1983    #[doc(hidden)]
1984    fn app_mut(&mut self) -> &mut AppContext {
1985        self.borrow_mut()
1986    }
1987
1988    #[doc(hidden)]
1989    fn app(&self) -> &AppContext {
1990        self.borrow()
1991    }
1992
1993    #[doc(hidden)]
1994    fn window(&self) -> &Window {
1995        self.borrow()
1996    }
1997
1998    #[doc(hidden)]
1999    fn window_mut(&mut self) -> &mut Window {
2000        self.borrow_mut()
2001    }
2002}
2003
2004impl Borrow<Window> for WindowContext<'_> {
2005    fn borrow(&self) -> &Window {
2006        self.window
2007    }
2008}
2009
2010impl BorrowMut<Window> for WindowContext<'_> {
2011    fn borrow_mut(&mut self) -> &mut Window {
2012        self.window
2013    }
2014}
2015
2016impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
2017
2018/// Provides access to application state that is specialized for a particular [`View`].
2019/// Allows you to interact with focus, emit events, etc.
2020/// ViewContext also derefs to [`WindowContext`], giving you access to all of its methods as well.
2021/// When you call [`View::update`], you're passed a `&mut V` and an `&mut ViewContext<V>`.
2022pub struct ViewContext<'a, V> {
2023    window_cx: WindowContext<'a>,
2024    view: &'a View<V>,
2025}
2026
2027impl<V> Borrow<AppContext> for ViewContext<'_, V> {
2028    fn borrow(&self) -> &AppContext {
2029        &*self.window_cx.app
2030    }
2031}
2032
2033impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
2034    fn borrow_mut(&mut self) -> &mut AppContext {
2035        &mut *self.window_cx.app
2036    }
2037}
2038
2039impl<V> Borrow<Window> for ViewContext<'_, V> {
2040    fn borrow(&self) -> &Window {
2041        &*self.window_cx.window
2042    }
2043}
2044
2045impl<V> BorrowMut<Window> for ViewContext<'_, V> {
2046    fn borrow_mut(&mut self) -> &mut Window {
2047        &mut *self.window_cx.window
2048    }
2049}
2050
2051impl<'a, V: 'static> ViewContext<'a, V> {
2052    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
2053        Self {
2054            window_cx: WindowContext::new(app, window),
2055            view,
2056        }
2057    }
2058
2059    /// Get the entity_id of this view.
2060    pub fn entity_id(&self) -> EntityId {
2061        self.view.entity_id()
2062    }
2063
2064    /// Get the view pointer underlying this context.
2065    pub fn view(&self) -> &View<V> {
2066        self.view
2067    }
2068
2069    /// Get the model underlying this view.
2070    pub fn model(&self) -> &Model<V> {
2071        &self.view.model
2072    }
2073
2074    /// Access the underlying window context.
2075    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
2076        &mut self.window_cx
2077    }
2078
2079    /// Sets a given callback to be run on the next frame.
2080    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
2081    where
2082        V: 'static,
2083    {
2084        let view = self.view().clone();
2085        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
2086    }
2087
2088    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
2089    /// that are currently on the stack to be returned to the app.
2090    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
2091        let view = self.view().downgrade();
2092        self.window_cx.defer(move |cx| {
2093            view.update(cx, f).ok();
2094        });
2095    }
2096
2097    /// Observe another model or view for changes to its state, as tracked by [`ModelContext::notify`].
2098    pub fn observe<V2, E>(
2099        &mut self,
2100        entity: &E,
2101        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
2102    ) -> Subscription
2103    where
2104        V2: 'static,
2105        V: 'static,
2106        E: Entity<V2>,
2107    {
2108        let view = self.view().downgrade();
2109        let entity_id = entity.entity_id();
2110        let entity = entity.downgrade();
2111        let window_handle = self.window.handle;
2112        self.app.new_observer(
2113            entity_id,
2114            Box::new(move |cx| {
2115                window_handle
2116                    .update(cx, |_, cx| {
2117                        if let Some(handle) = E::upgrade_from(&entity) {
2118                            view.update(cx, |this, cx| on_notify(this, handle, cx))
2119                                .is_ok()
2120                        } else {
2121                            false
2122                        }
2123                    })
2124                    .unwrap_or(false)
2125            }),
2126        )
2127    }
2128
2129    /// Subscribe to events emitted by another model or view.
2130    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
2131    /// 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.
2132    pub fn subscribe<V2, E, Evt>(
2133        &mut self,
2134        entity: &E,
2135        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2136    ) -> Subscription
2137    where
2138        V2: EventEmitter<Evt>,
2139        E: Entity<V2>,
2140        Evt: 'static,
2141    {
2142        let view = self.view().downgrade();
2143        let entity_id = entity.entity_id();
2144        let handle = entity.downgrade();
2145        let window_handle = self.window.handle;
2146        self.app.new_subscription(
2147            entity_id,
2148            (
2149                TypeId::of::<Evt>(),
2150                Box::new(move |event, cx| {
2151                    window_handle
2152                        .update(cx, |_, cx| {
2153                            if let Some(handle) = E::upgrade_from(&handle) {
2154                                let event = event.downcast_ref().expect("invalid event type");
2155                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2156                                    .is_ok()
2157                            } else {
2158                                false
2159                            }
2160                        })
2161                        .unwrap_or(false)
2162                }),
2163            ),
2164        )
2165    }
2166
2167    /// Register a callback to be invoked when the view is released.
2168    ///
2169    /// The callback receives a handle to the view's window. This handle may be
2170    /// invalid, if the window was closed before the view was released.
2171    pub fn on_release(
2172        &mut self,
2173        on_release: impl FnOnce(&mut V, AnyWindowHandle, &mut AppContext) + 'static,
2174    ) -> Subscription {
2175        let window_handle = self.window.handle;
2176        let (subscription, activate) = self.app.release_listeners.insert(
2177            self.view.model.entity_id,
2178            Box::new(move |this, cx| {
2179                let this = this.downcast_mut().expect("invalid entity type");
2180                on_release(this, window_handle, cx)
2181            }),
2182        );
2183        activate();
2184        subscription
2185    }
2186
2187    /// Register a callback to be invoked when the given Model or View is released.
2188    pub fn observe_release<V2, E>(
2189        &mut self,
2190        entity: &E,
2191        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2192    ) -> Subscription
2193    where
2194        V: 'static,
2195        V2: 'static,
2196        E: Entity<V2>,
2197    {
2198        let view = self.view().downgrade();
2199        let entity_id = entity.entity_id();
2200        let window_handle = self.window.handle;
2201        let (subscription, activate) = self.app.release_listeners.insert(
2202            entity_id,
2203            Box::new(move |entity, cx| {
2204                let entity = entity.downcast_mut().expect("invalid entity type");
2205                let _ = window_handle.update(cx, |_, cx| {
2206                    view.update(cx, |this, cx| on_release(this, entity, cx))
2207                });
2208            }),
2209        );
2210        activate();
2211        subscription
2212    }
2213
2214    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
2215    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
2216    pub fn notify(&mut self) {
2217        self.window_cx.notify(self.view.entity_id());
2218    }
2219
2220    /// Register a callback to be invoked when the window is resized.
2221    pub fn observe_window_bounds(
2222        &mut self,
2223        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2224    ) -> Subscription {
2225        let view = self.view.downgrade();
2226        let (subscription, activate) = self.window.bounds_observers.insert(
2227            (),
2228            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2229        );
2230        activate();
2231        subscription
2232    }
2233
2234    /// Register a callback to be invoked when the window is activated or deactivated.
2235    pub fn observe_window_activation(
2236        &mut self,
2237        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2238    ) -> Subscription {
2239        let view = self.view.downgrade();
2240        let (subscription, activate) = self.window.activation_observers.insert(
2241            (),
2242            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2243        );
2244        activate();
2245        subscription
2246    }
2247
2248    /// Registers a callback to be invoked when the window appearance changes.
2249    pub fn observe_window_appearance(
2250        &mut self,
2251        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2252    ) -> Subscription {
2253        let view = self.view.downgrade();
2254        let (subscription, activate) = self.window.appearance_observers.insert(
2255            (),
2256            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2257        );
2258        activate();
2259        subscription
2260    }
2261
2262    /// Register a listener to be called when the given focus handle receives focus.
2263    /// Returns a subscription and persists until the subscription is dropped.
2264    pub fn on_focus(
2265        &mut self,
2266        handle: &FocusHandle,
2267        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2268    ) -> Subscription {
2269        let view = self.view.downgrade();
2270        let focus_id = handle.id;
2271        let (subscription, activate) =
2272            self.window.new_focus_listener(Box::new(move |event, cx| {
2273                view.update(cx, |view, cx| {
2274                    if event.previous_focus_path.last() != Some(&focus_id)
2275                        && event.current_focus_path.last() == Some(&focus_id)
2276                    {
2277                        listener(view, cx)
2278                    }
2279                })
2280                .is_ok()
2281            }));
2282        self.app.defer(|_| activate());
2283        subscription
2284    }
2285
2286    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2287    /// Returns a subscription and persists until the subscription is dropped.
2288    pub fn on_focus_in(
2289        &mut self,
2290        handle: &FocusHandle,
2291        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2292    ) -> Subscription {
2293        let view = self.view.downgrade();
2294        let focus_id = handle.id;
2295        let (subscription, activate) =
2296            self.window.new_focus_listener(Box::new(move |event, cx| {
2297                view.update(cx, |view, cx| {
2298                    if !event.previous_focus_path.contains(&focus_id)
2299                        && event.current_focus_path.contains(&focus_id)
2300                    {
2301                        listener(view, cx)
2302                    }
2303                })
2304                .is_ok()
2305            }));
2306        self.app.defer(move |_| activate());
2307        subscription
2308    }
2309
2310    /// Register a listener to be called when the given focus handle loses focus.
2311    /// Returns a subscription and persists until the subscription is dropped.
2312    pub fn on_blur(
2313        &mut self,
2314        handle: &FocusHandle,
2315        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2316    ) -> Subscription {
2317        let view = self.view.downgrade();
2318        let focus_id = handle.id;
2319        let (subscription, activate) =
2320            self.window.new_focus_listener(Box::new(move |event, cx| {
2321                view.update(cx, |view, cx| {
2322                    if event.previous_focus_path.last() == Some(&focus_id)
2323                        && event.current_focus_path.last() != Some(&focus_id)
2324                    {
2325                        listener(view, cx)
2326                    }
2327                })
2328                .is_ok()
2329            }));
2330        self.app.defer(move |_| activate());
2331        subscription
2332    }
2333
2334    /// Register a listener to be called when nothing in the window has focus.
2335    /// This typically happens when the node that was focused is removed from the tree,
2336    /// and this callback lets you chose a default place to restore the users focus.
2337    /// Returns a subscription and persists until the subscription is dropped.
2338    pub fn on_focus_lost(
2339        &mut self,
2340        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2341    ) -> Subscription {
2342        let view = self.view.downgrade();
2343        let (subscription, activate) = self.window.focus_lost_listeners.insert(
2344            (),
2345            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2346        );
2347        activate();
2348        subscription
2349    }
2350
2351    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2352    /// Returns a subscription and persists until the subscription is dropped.
2353    pub fn on_focus_out(
2354        &mut self,
2355        handle: &FocusHandle,
2356        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2357    ) -> Subscription {
2358        let view = self.view.downgrade();
2359        let focus_id = handle.id;
2360        let (subscription, activate) =
2361            self.window.new_focus_listener(Box::new(move |event, cx| {
2362                view.update(cx, |view, cx| {
2363                    if event.previous_focus_path.contains(&focus_id)
2364                        && !event.current_focus_path.contains(&focus_id)
2365                    {
2366                        listener(view, cx)
2367                    }
2368                })
2369                .is_ok()
2370            }));
2371        self.app.defer(move |_| activate());
2372        subscription
2373    }
2374
2375    /// Schedule a future to be run asynchronously.
2376    /// The given callback is invoked with a [`WeakView<V>`] to avoid leaking the view for a long-running process.
2377    /// It's also given an [`AsyncWindowContext`], which can be used to access the state of the view across await points.
2378    /// The returned future will be polled on the main thread.
2379    pub fn spawn<Fut, R>(
2380        &mut self,
2381        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2382    ) -> Task<R>
2383    where
2384        R: 'static,
2385        Fut: Future<Output = R> + 'static,
2386    {
2387        let view = self.view().downgrade();
2388        self.window_cx.spawn(|cx| f(view, cx))
2389    }
2390
2391    /// Updates the global state of the given type.
2392    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2393    where
2394        G: Global,
2395    {
2396        let mut global = self.app.lease_global::<G>();
2397        let result = f(&mut global, self);
2398        self.app.end_global_lease(global);
2399        result
2400    }
2401
2402    /// Register a callback to be invoked when the given global state changes.
2403    pub fn observe_global<G: Global>(
2404        &mut self,
2405        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2406    ) -> Subscription {
2407        let window_handle = self.window.handle;
2408        let view = self.view().downgrade();
2409        let (subscription, activate) = self.global_observers.insert(
2410            TypeId::of::<G>(),
2411            Box::new(move |cx| {
2412                window_handle
2413                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2414                    .unwrap_or(false)
2415            }),
2416        );
2417        self.app.defer(move |_| activate());
2418        subscription
2419    }
2420
2421    /// Register a callback to be invoked when the given Action type is dispatched to the window.
2422    pub fn on_action(
2423        &mut self,
2424        action_type: TypeId,
2425        listener: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2426    ) {
2427        let handle = self.view().clone();
2428        self.window_cx
2429            .on_action(action_type, move |action, phase, cx| {
2430                handle.update(cx, |view, cx| {
2431                    listener(view, action, phase, cx);
2432                })
2433            });
2434    }
2435
2436    /// Emit an event to be handled any other views that have subscribed via [ViewContext::subscribe].
2437    pub fn emit<Evt>(&mut self, event: Evt)
2438    where
2439        Evt: 'static,
2440        V: EventEmitter<Evt>,
2441    {
2442        let emitter = self.view.model.entity_id;
2443        self.app.push_effect(Effect::Emit {
2444            emitter,
2445            event_type: TypeId::of::<Evt>(),
2446            event: Box::new(event),
2447        });
2448    }
2449
2450    /// Move focus to the current view, assuming it implements [`FocusableView`].
2451    pub fn focus_self(&mut self)
2452    where
2453        V: FocusableView,
2454    {
2455        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2456    }
2457
2458    /// Convenience method for accessing view state in an event callback.
2459    ///
2460    /// Many GPUI callbacks take the form of `Fn(&E, &mut WindowContext)`,
2461    /// but it's often useful to be able to access view state in these
2462    /// callbacks. This method provides a convenient way to do so.
2463    pub fn listener<E>(
2464        &self,
2465        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2466    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2467        let view = self.view().downgrade();
2468        move |e: &E, cx: &mut WindowContext| {
2469            view.update(cx, |view, cx| f(view, e, cx)).ok();
2470        }
2471    }
2472}
2473
2474impl<V> Context for ViewContext<'_, V> {
2475    type Result<U> = U;
2476
2477    fn new_model<T: 'static>(
2478        &mut self,
2479        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2480    ) -> Model<T> {
2481        self.window_cx.new_model(build_model)
2482    }
2483
2484    fn update_model<T: 'static, R>(
2485        &mut self,
2486        model: &Model<T>,
2487        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2488    ) -> R {
2489        self.window_cx.update_model(model, update)
2490    }
2491
2492    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2493    where
2494        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2495    {
2496        self.window_cx.update_window(window, update)
2497    }
2498
2499    fn read_model<T, R>(
2500        &self,
2501        handle: &Model<T>,
2502        read: impl FnOnce(&T, &AppContext) -> R,
2503    ) -> Self::Result<R>
2504    where
2505        T: 'static,
2506    {
2507        self.window_cx.read_model(handle, read)
2508    }
2509
2510    fn read_window<T, R>(
2511        &self,
2512        window: &WindowHandle<T>,
2513        read: impl FnOnce(View<T>, &AppContext) -> R,
2514    ) -> Result<R>
2515    where
2516        T: 'static,
2517    {
2518        self.window_cx.read_window(window, read)
2519    }
2520}
2521
2522impl<V: 'static> VisualContext for ViewContext<'_, V> {
2523    fn new_view<W: Render + 'static>(
2524        &mut self,
2525        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2526    ) -> Self::Result<View<W>> {
2527        self.window_cx.new_view(build_view_state)
2528    }
2529
2530    fn update_view<V2: 'static, R>(
2531        &mut self,
2532        view: &View<V2>,
2533        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2534    ) -> Self::Result<R> {
2535        self.window_cx.update_view(view, update)
2536    }
2537
2538    fn replace_root_view<W>(
2539        &mut self,
2540        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2541    ) -> Self::Result<View<W>>
2542    where
2543        W: 'static + Render,
2544    {
2545        self.window_cx.replace_root_view(build_view)
2546    }
2547
2548    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2549        self.window_cx.focus_view(view)
2550    }
2551
2552    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2553        self.window_cx.dismiss_view(view)
2554    }
2555}
2556
2557impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2558    type Target = WindowContext<'a>;
2559
2560    fn deref(&self) -> &Self::Target {
2561        &self.window_cx
2562    }
2563}
2564
2565impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2566    fn deref_mut(&mut self) -> &mut Self::Target {
2567        &mut self.window_cx
2568    }
2569}
2570
2571// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2572slotmap::new_key_type! {
2573    /// A unique identifier for a window.
2574    pub struct WindowId;
2575}
2576
2577impl WindowId {
2578    /// Converts this window ID to a `u64`.
2579    pub fn as_u64(&self) -> u64 {
2580        self.0.as_ffi()
2581    }
2582}
2583
2584/// A handle to a window with a specific root view type.
2585/// Note that this does not keep the window alive on its own.
2586#[derive(Deref, DerefMut)]
2587pub struct WindowHandle<V> {
2588    #[deref]
2589    #[deref_mut]
2590    pub(crate) any_handle: AnyWindowHandle,
2591    state_type: PhantomData<V>,
2592}
2593
2594impl<V: 'static + Render> WindowHandle<V> {
2595    /// Creates a new handle from a window ID.
2596    /// This does not check if the root type of the window is `V`.
2597    pub fn new(id: WindowId) -> Self {
2598        WindowHandle {
2599            any_handle: AnyWindowHandle {
2600                id,
2601                state_type: TypeId::of::<V>(),
2602            },
2603            state_type: PhantomData,
2604        }
2605    }
2606
2607    /// Get the root view out of this window.
2608    ///
2609    /// This will fail if the window is closed or if the root view's type does not match `V`.
2610    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2611    where
2612        C: Context,
2613    {
2614        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2615            root_view
2616                .downcast::<V>()
2617                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2618        }))
2619    }
2620
2621    /// Updates the root view of this window.
2622    ///
2623    /// This will fail if the window has been closed or if the root view's type does not match
2624    pub fn update<C, R>(
2625        &self,
2626        cx: &mut C,
2627        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2628    ) -> Result<R>
2629    where
2630        C: Context,
2631    {
2632        cx.update_window(self.any_handle, |root_view, cx| {
2633            let view = root_view
2634                .downcast::<V>()
2635                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2636            Ok(cx.update_view(&view, update))
2637        })?
2638    }
2639
2640    /// Read the root view out of this window.
2641    ///
2642    /// This will fail if the window is closed or if the root view's type does not match `V`.
2643    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2644        let x = cx
2645            .windows
2646            .get(self.id)
2647            .and_then(|window| {
2648                window
2649                    .as_ref()
2650                    .and_then(|window| window.root_view.clone())
2651                    .map(|root_view| root_view.downcast::<V>())
2652            })
2653            .ok_or_else(|| anyhow!("window not found"))?
2654            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2655
2656        Ok(x.read(cx))
2657    }
2658
2659    /// Read the root view out of this window, with a callback
2660    ///
2661    /// This will fail if the window is closed or if the root view's type does not match `V`.
2662    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2663    where
2664        C: Context,
2665    {
2666        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2667    }
2668
2669    /// Read the root view pointer off of this window.
2670    ///
2671    /// This will fail if the window is closed or if the root view's type does not match `V`.
2672    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2673    where
2674        C: Context,
2675    {
2676        cx.read_window(self, |root_view, _cx| root_view.clone())
2677    }
2678
2679    /// Check if this window is 'active'.
2680    ///
2681    /// Will return `None` if the window is closed or currently
2682    /// borrowed.
2683    pub fn is_active(&self, cx: &mut AppContext) -> Option<bool> {
2684        cx.update_window(self.any_handle, |_, cx| cx.is_window_active())
2685            .ok()
2686    }
2687}
2688
2689impl<V> Copy for WindowHandle<V> {}
2690
2691impl<V> Clone for WindowHandle<V> {
2692    fn clone(&self) -> Self {
2693        *self
2694    }
2695}
2696
2697impl<V> PartialEq for WindowHandle<V> {
2698    fn eq(&self, other: &Self) -> bool {
2699        self.any_handle == other.any_handle
2700    }
2701}
2702
2703impl<V> Eq for WindowHandle<V> {}
2704
2705impl<V> Hash for WindowHandle<V> {
2706    fn hash<H: Hasher>(&self, state: &mut H) {
2707        self.any_handle.hash(state);
2708    }
2709}
2710
2711impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle {
2712    fn from(val: WindowHandle<V>) -> Self {
2713        val.any_handle
2714    }
2715}
2716
2717/// A handle to a window with any root view type, which can be downcast to a window with a specific root view type.
2718#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2719pub struct AnyWindowHandle {
2720    pub(crate) id: WindowId,
2721    state_type: TypeId,
2722}
2723
2724impl AnyWindowHandle {
2725    /// Get the ID of this window.
2726    pub fn window_id(&self) -> WindowId {
2727        self.id
2728    }
2729
2730    /// Attempt to convert this handle to a window handle with a specific root view type.
2731    /// If the types do not match, this will return `None`.
2732    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2733        if TypeId::of::<T>() == self.state_type {
2734            Some(WindowHandle {
2735                any_handle: *self,
2736                state_type: PhantomData,
2737            })
2738        } else {
2739            None
2740        }
2741    }
2742
2743    /// Updates the state of the root view of this window.
2744    ///
2745    /// This will fail if the window has been closed.
2746    pub fn update<C, R>(
2747        self,
2748        cx: &mut C,
2749        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2750    ) -> Result<R>
2751    where
2752        C: Context,
2753    {
2754        cx.update_window(self, update)
2755    }
2756
2757    /// Read the state of the root view of this window.
2758    ///
2759    /// This will fail if the window has been closed.
2760    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2761    where
2762        C: Context,
2763        T: 'static,
2764    {
2765        let view = self
2766            .downcast::<T>()
2767            .context("the type of the window's root view has changed")?;
2768
2769        cx.read_window(&view, read)
2770    }
2771}
2772
2773/// An identifier for an [`Element`](crate::Element).
2774///
2775/// Can be constructed with a string, a number, or both, as well
2776/// as other internal representations.
2777#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2778pub enum ElementId {
2779    /// The ID of a View element
2780    View(EntityId),
2781    /// An integer ID.
2782    Integer(usize),
2783    /// A string based ID.
2784    Name(SharedString),
2785    /// An ID that's equated with a focus handle.
2786    FocusHandle(FocusId),
2787    /// A combination of a name and an integer.
2788    NamedInteger(SharedString, usize),
2789}
2790
2791impl Display for ElementId {
2792    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
2793        match self {
2794            ElementId::View(entity_id) => write!(f, "view-{}", entity_id)?,
2795            ElementId::Integer(ix) => write!(f, "{}", ix)?,
2796            ElementId::Name(name) => write!(f, "{}", name)?,
2797            ElementId::FocusHandle(_) => write!(f, "FocusHandle")?,
2798            ElementId::NamedInteger(s, i) => write!(f, "{}-{}", s, i)?,
2799        }
2800
2801        Ok(())
2802    }
2803}
2804
2805impl TryInto<SharedString> for ElementId {
2806    type Error = anyhow::Error;
2807
2808    fn try_into(self) -> anyhow::Result<SharedString> {
2809        if let ElementId::Name(name) = self {
2810            Ok(name)
2811        } else {
2812            Err(anyhow!("element id is not string"))
2813        }
2814    }
2815}
2816
2817impl From<usize> for ElementId {
2818    fn from(id: usize) -> Self {
2819        ElementId::Integer(id)
2820    }
2821}
2822
2823impl From<i32> for ElementId {
2824    fn from(id: i32) -> Self {
2825        Self::Integer(id as usize)
2826    }
2827}
2828
2829impl From<SharedString> for ElementId {
2830    fn from(name: SharedString) -> Self {
2831        ElementId::Name(name)
2832    }
2833}
2834
2835impl From<&'static str> for ElementId {
2836    fn from(name: &'static str) -> Self {
2837        ElementId::Name(name.into())
2838    }
2839}
2840
2841impl<'a> From<&'a FocusHandle> for ElementId {
2842    fn from(handle: &'a FocusHandle) -> Self {
2843        ElementId::FocusHandle(handle.id)
2844    }
2845}
2846
2847impl From<(&'static str, EntityId)> for ElementId {
2848    fn from((name, id): (&'static str, EntityId)) -> Self {
2849        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2850    }
2851}
2852
2853impl From<(&'static str, usize)> for ElementId {
2854    fn from((name, id): (&'static str, usize)) -> Self {
2855        ElementId::NamedInteger(name.into(), id)
2856    }
2857}
2858
2859impl From<(&'static str, u64)> for ElementId {
2860    fn from((name, id): (&'static str, u64)) -> Self {
2861        ElementId::NamedInteger(name.into(), id as usize)
2862    }
2863}
2864
2865/// A rectangle to be rendered in the window at the given position and size.
2866/// Passed as an argument [`ElementContext::paint_quad`].
2867#[derive(Clone)]
2868pub struct PaintQuad {
2869    bounds: Bounds<Pixels>,
2870    corner_radii: Corners<Pixels>,
2871    background: Hsla,
2872    border_widths: Edges<Pixels>,
2873    border_color: Hsla,
2874}
2875
2876impl PaintQuad {
2877    /// Sets the corner radii of the quad.
2878    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
2879        PaintQuad {
2880            corner_radii: corner_radii.into(),
2881            ..self
2882        }
2883    }
2884
2885    /// Sets the border widths of the quad.
2886    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
2887        PaintQuad {
2888            border_widths: border_widths.into(),
2889            ..self
2890        }
2891    }
2892
2893    /// Sets the border color of the quad.
2894    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
2895        PaintQuad {
2896            border_color: border_color.into(),
2897            ..self
2898        }
2899    }
2900
2901    /// Sets the background color of the quad.
2902    pub fn background(self, background: impl Into<Hsla>) -> Self {
2903        PaintQuad {
2904            background: background.into(),
2905            ..self
2906        }
2907    }
2908}
2909
2910/// Creates a quad with the given parameters.
2911pub fn quad(
2912    bounds: Bounds<Pixels>,
2913    corner_radii: impl Into<Corners<Pixels>>,
2914    background: impl Into<Hsla>,
2915    border_widths: impl Into<Edges<Pixels>>,
2916    border_color: impl Into<Hsla>,
2917) -> PaintQuad {
2918    PaintQuad {
2919        bounds,
2920        corner_radii: corner_radii.into(),
2921        background: background.into(),
2922        border_widths: border_widths.into(),
2923        border_color: border_color.into(),
2924    }
2925}
2926
2927/// Creates a filled quad with the given bounds and background color.
2928pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
2929    PaintQuad {
2930        bounds: bounds.into(),
2931        corner_radii: (0.).into(),
2932        background: background.into(),
2933        border_widths: (0.).into(),
2934        border_color: transparent_black(),
2935    }
2936}
2937
2938/// Creates a rectangle outline with the given bounds, border color, and a 1px border width
2939pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
2940    PaintQuad {
2941        bounds: bounds.into(),
2942        corner_radii: (0.).into(),
2943        background: transparent_black(),
2944        border_widths: (1.).into(),
2945        border_color: border_color.into(),
2946    }
2947}