window.rs

   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    MouseButton, MouseMoveEvent, MouseUpEvent, Pixels, PlatformAtlas, PlatformDisplay,
   8    PlatformInput, PlatformWindow, Point, PromptLevel, Render, ScaledPixels, SharedString, Size,
   9    SubscriberSet, Subscription, TaffyLayoutEngine, Task, TextStyle, TextStyleRefinement, View,
  10    VisualContext, WeakView, WindowAppearance, WindowOptions, WindowParams, WindowTextSystem,
  11};
  12use anyhow::{anyhow, Context as _, Result};
  13use collections::FxHashSet;
  14use derive_more::{Deref, DerefMut};
  15use futures::channel::oneshot;
  16use parking_lot::RwLock;
  17use refineable::Refineable;
  18use slotmap::SlotMap;
  19use smallvec::SmallVec;
  20use std::{
  21    any::{Any, TypeId},
  22    borrow::{Borrow, BorrowMut},
  23    cell::{Cell, RefCell},
  24    fmt::{Debug, Display},
  25    future::Future,
  26    hash::{Hash, Hasher},
  27    marker::PhantomData,
  28    mem,
  29    rc::Rc,
  30    sync::{
  31        atomic::{AtomicUsize, Ordering::SeqCst},
  32        Arc, Weak,
  33    },
  34    time::{Duration, Instant},
  35};
  36use util::{measure, ResultExt};
  37
  38mod element_cx;
  39mod prompts;
  40
  41pub use element_cx::*;
  42pub use prompts::*;
  43
  44/// Represents the two different phases when dispatching events.
  45#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  46pub enum DispatchPhase {
  47    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  48    /// invoked front to back and keyboard event listeners are invoked from the focused element
  49    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  50    /// registering event listeners.
  51    #[default]
  52    Bubble,
  53    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  54    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  55    /// is used for special purposes such as clearing the "pressed" state for click events. If
  56    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  57    /// outside of the immediate region may rely on detecting non-local events during this phase.
  58    Capture,
  59}
  60
  61impl DispatchPhase {
  62    /// Returns true if this represents the "bubble" phase.
  63    pub fn bubble(self) -> bool {
  64        self == DispatchPhase::Bubble
  65    }
  66
  67    /// Returns true if this represents the "capture" phase.
  68    pub fn capture(self) -> bool {
  69        self == DispatchPhase::Capture
  70    }
  71}
  72
  73type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
  74
  75type AnyWindowFocusListener = Box<dyn FnMut(&FocusEvent, &mut WindowContext) -> bool + 'static>;
  76
  77struct FocusEvent {
  78    previous_focus_path: SmallVec<[FocusId; 8]>,
  79    current_focus_path: SmallVec<[FocusId; 8]>,
  80}
  81
  82slotmap::new_key_type! {
  83    /// A globally unique identifier for a focusable element.
  84    pub struct FocusId;
  85}
  86
  87thread_local! {
  88    pub(crate) static ELEMENT_ARENA: RefCell<Arena> = RefCell::new(Arena::new(8 * 1024 * 1024));
  89}
  90
  91impl FocusId {
  92    /// Obtains whether the element associated with this handle is currently focused.
  93    pub fn is_focused(&self, cx: &WindowContext) -> bool {
  94        cx.window.focus == Some(*self)
  95    }
  96
  97    /// Obtains whether the element associated with this handle contains the focused
  98    /// element or is itself focused.
  99    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 100        cx.focused()
 101            .map_or(false, |focused| self.contains(focused.id, cx))
 102    }
 103
 104    /// Obtains whether the element associated with this handle is contained within the
 105    /// focused element or is itself focused.
 106    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 107        let focused = cx.focused();
 108        focused.map_or(false, |focused| focused.id.contains(*self, cx))
 109    }
 110
 111    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 112    pub(crate) fn contains(&self, other: Self, cx: &WindowContext) -> bool {
 113        cx.window
 114            .rendered_frame
 115            .dispatch_tree
 116            .focus_contains(*self, other)
 117    }
 118}
 119
 120/// A handle which can be used to track and manipulate the focused element in a window.
 121pub struct FocusHandle {
 122    pub(crate) id: FocusId,
 123    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 124}
 125
 126impl std::fmt::Debug for FocusHandle {
 127    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 128        f.write_fmt(format_args!("FocusHandle({:?})", self.id))
 129    }
 130}
 131
 132impl FocusHandle {
 133    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
 134        let id = handles.write().insert(AtomicUsize::new(1));
 135        Self {
 136            id,
 137            handles: handles.clone(),
 138        }
 139    }
 140
 141    pub(crate) fn for_id(
 142        id: FocusId,
 143        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 144    ) -> Option<Self> {
 145        let lock = handles.read();
 146        let ref_count = lock.get(id)?;
 147        if ref_count.load(SeqCst) == 0 {
 148            None
 149        } else {
 150            ref_count.fetch_add(1, SeqCst);
 151            Some(Self {
 152                id,
 153                handles: handles.clone(),
 154            })
 155        }
 156    }
 157
 158    /// Converts this focus handle into a weak variant, which does not prevent it from being released.
 159    pub fn downgrade(&self) -> WeakFocusHandle {
 160        WeakFocusHandle {
 161            id: self.id,
 162            handles: Arc::downgrade(&self.handles),
 163        }
 164    }
 165
 166    /// Moves the focus to the element associated with this handle.
 167    pub fn focus(&self, cx: &mut WindowContext) {
 168        cx.focus(self)
 169    }
 170
 171    /// Obtains whether the element associated with this handle is currently focused.
 172    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 173        self.id.is_focused(cx)
 174    }
 175
 176    /// Obtains whether the element associated with this handle contains the focused
 177    /// element or is itself focused.
 178    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 179        self.id.contains_focused(cx)
 180    }
 181
 182    /// Obtains whether the element associated with this handle is contained within the
 183    /// focused element or is itself focused.
 184    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 185        self.id.within_focused(cx)
 186    }
 187
 188    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 189    pub fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 190        self.id.contains(other.id, cx)
 191    }
 192}
 193
 194impl Clone for FocusHandle {
 195    fn clone(&self) -> Self {
 196        Self::for_id(self.id, &self.handles).unwrap()
 197    }
 198}
 199
 200impl PartialEq for FocusHandle {
 201    fn eq(&self, other: &Self) -> bool {
 202        self.id == other.id
 203    }
 204}
 205
 206impl Eq for FocusHandle {}
 207
 208impl Drop for FocusHandle {
 209    fn drop(&mut self) {
 210        self.handles
 211            .read()
 212            .get(self.id)
 213            .unwrap()
 214            .fetch_sub(1, SeqCst);
 215    }
 216}
 217
 218/// A weak reference to a focus handle.
 219#[derive(Clone, Debug)]
 220pub struct WeakFocusHandle {
 221    pub(crate) id: FocusId,
 222    handles: Weak<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 223}
 224
 225impl WeakFocusHandle {
 226    /// Attempts to upgrade the [WeakFocusHandle] to a [FocusHandle].
 227    pub fn upgrade(&self) -> Option<FocusHandle> {
 228        let handles = self.handles.upgrade()?;
 229        FocusHandle::for_id(self.id, &handles)
 230    }
 231}
 232
 233impl PartialEq for WeakFocusHandle {
 234    fn eq(&self, other: &WeakFocusHandle) -> bool {
 235        self.id == other.id
 236    }
 237}
 238
 239impl Eq for WeakFocusHandle {}
 240
 241impl PartialEq<FocusHandle> for WeakFocusHandle {
 242    fn eq(&self, other: &FocusHandle) -> bool {
 243        self.id == other.id
 244    }
 245}
 246
 247impl PartialEq<WeakFocusHandle> for FocusHandle {
 248    fn eq(&self, other: &WeakFocusHandle) -> bool {
 249        self.id == other.id
 250    }
 251}
 252
 253/// FocusableView allows users of your view to easily
 254/// focus it (using cx.focus_view(view))
 255pub trait FocusableView: 'static + Render {
 256    /// Returns the focus handle associated with this view.
 257    fn focus_handle(&self, cx: &AppContext) -> FocusHandle;
 258}
 259
 260/// ManagedView is a view (like a Modal, Popover, Menu, etc.)
 261/// where the lifecycle of the view is handled by another view.
 262pub trait ManagedView: FocusableView + EventEmitter<DismissEvent> {}
 263
 264impl<M: FocusableView + EventEmitter<DismissEvent>> ManagedView for M {}
 265
 266/// Emitted by implementers of [`ManagedView`] to indicate the view should be dismissed, such as when a view is presented as a modal.
 267pub struct DismissEvent;
 268
 269type FrameCallback = Box<dyn FnOnce(&mut WindowContext)>;
 270
 271// Holds the state for a specific window.
 272#[doc(hidden)]
 273pub struct Window {
 274    pub(crate) handle: AnyWindowHandle,
 275    pub(crate) removed: bool,
 276    pub(crate) platform_window: Box<dyn PlatformWindow>,
 277    display_id: DisplayId,
 278    sprite_atlas: Arc<dyn PlatformAtlas>,
 279    text_system: Arc<WindowTextSystem>,
 280    pub(crate) rem_size: Pixels,
 281    pub(crate) viewport_size: Size<Pixels>,
 282    layout_engine: Option<TaffyLayoutEngine>,
 283    pub(crate) root_view: Option<AnyView>,
 284    pub(crate) element_id_stack: GlobalElementId,
 285    pub(crate) text_style_stack: Vec<TextStyleRefinement>,
 286    pub(crate) rendered_frame: Frame,
 287    pub(crate) next_frame: Frame,
 288    pub(crate) next_hitbox_id: HitboxId,
 289    next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>>,
 290    pub(crate) dirty_views: FxHashSet<EntityId>,
 291    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 292    focus_listeners: SubscriberSet<(), AnyWindowFocusListener>,
 293    focus_lost_listeners: SubscriberSet<(), AnyObserver>,
 294    default_prevented: bool,
 295    mouse_position: Point<Pixels>,
 296    mouse_hit_test: HitTest,
 297    modifiers: Modifiers,
 298    scale_factor: f32,
 299    bounds_observers: SubscriberSet<(), AnyObserver>,
 300    appearance: WindowAppearance,
 301    appearance_observers: SubscriberSet<(), AnyObserver>,
 302    active: Rc<Cell<bool>>,
 303    pub(crate) dirty: Rc<Cell<bool>>,
 304    pub(crate) needs_present: Rc<Cell<bool>>,
 305    pub(crate) last_input_timestamp: Rc<Cell<Instant>>,
 306    pub(crate) refreshing: bool,
 307    pub(crate) draw_phase: DrawPhase,
 308    activation_observers: SubscriberSet<(), AnyObserver>,
 309    pub(crate) focus: Option<FocusId>,
 310    focus_enabled: bool,
 311    pending_input: Option<PendingInput>,
 312    prompt: Option<RenderablePromptHandle>,
 313}
 314
 315#[derive(Clone, Copy, Debug, Eq, PartialEq)]
 316pub(crate) enum DrawPhase {
 317    None,
 318    Layout,
 319    Paint,
 320    Focus,
 321}
 322
 323#[derive(Default, Debug)]
 324struct PendingInput {
 325    keystrokes: SmallVec<[Keystroke; 1]>,
 326    bindings: SmallVec<[KeyBinding; 1]>,
 327    focus: Option<FocusId>,
 328    timer: Option<Task<()>>,
 329}
 330
 331impl PendingInput {
 332    fn input(&self) -> String {
 333        self.keystrokes
 334            .iter()
 335            .flat_map(|k| k.ime_key.clone())
 336            .collect::<Vec<String>>()
 337            .join("")
 338    }
 339
 340    fn used_by_binding(&self, binding: &KeyBinding) -> bool {
 341        if self.keystrokes.is_empty() {
 342            return true;
 343        }
 344        let keystroke = &self.keystrokes[0];
 345        for candidate in keystroke.match_candidates() {
 346            if binding.match_keystrokes(&[candidate]) == KeyMatch::Pending {
 347                return true;
 348            }
 349        }
 350        false
 351    }
 352}
 353
 354pub(crate) struct ElementStateBox {
 355    pub(crate) inner: Box<dyn Any>,
 356    #[cfg(debug_assertions)]
 357    pub(crate) type_name: &'static str,
 358}
 359
 360fn default_bounds(cx: &mut AppContext) -> Bounds<GlobalPixels> {
 361    const DEFAULT_WINDOW_SIZE: Size<GlobalPixels> = size(GlobalPixels(1024.0), GlobalPixels(700.0));
 362    const DEFAULT_WINDOW_OFFSET: Point<GlobalPixels> = point(GlobalPixels(0.0), GlobalPixels(35.0));
 363
 364    cx.active_window()
 365        .and_then(|w| w.update(cx, |_, cx| cx.window_bounds()).ok())
 366        .map(|bounds| bounds.map_origin(|origin| origin + DEFAULT_WINDOW_OFFSET))
 367        .unwrap_or_else(|| {
 368            cx.primary_display()
 369                .map(|display| {
 370                    let center = display.bounds().center();
 371                    let offset = DEFAULT_WINDOW_SIZE / 2.0;
 372                    let origin = point(center.x - offset.width, center.y - offset.height);
 373                    Bounds::new(origin, DEFAULT_WINDOW_SIZE)
 374                })
 375                .unwrap_or_else(|| {
 376                    Bounds::new(
 377                        point(GlobalPixels(0.0), GlobalPixels(0.0)),
 378                        DEFAULT_WINDOW_SIZE,
 379                    )
 380                })
 381        })
 382}
 383
 384impl Window {
 385    pub(crate) fn new(
 386        handle: AnyWindowHandle,
 387        options: WindowOptions,
 388        cx: &mut AppContext,
 389    ) -> Self {
 390        let WindowOptions {
 391            bounds,
 392            titlebar,
 393            focus,
 394            show,
 395            kind,
 396            is_movable,
 397            display_id,
 398            fullscreen,
 399        } = options;
 400
 401        let bounds = bounds.unwrap_or_else(|| default_bounds(cx));
 402        let platform_window = cx.platform.open_window(
 403            handle,
 404            WindowParams {
 405                bounds,
 406                titlebar,
 407                kind,
 408                is_movable,
 409                focus,
 410                show,
 411                display_id,
 412            },
 413        );
 414        let display_id = platform_window.display().id();
 415        let sprite_atlas = platform_window.sprite_atlas();
 416        let mouse_position = platform_window.mouse_position();
 417        let modifiers = platform_window.modifiers();
 418        let content_size = platform_window.content_size();
 419        let scale_factor = platform_window.scale_factor();
 420        let appearance = platform_window.appearance();
 421        let text_system = Arc::new(WindowTextSystem::new(cx.text_system().clone()));
 422        let dirty = Rc::new(Cell::new(true));
 423        let active = Rc::new(Cell::new(false));
 424        let needs_present = Rc::new(Cell::new(false));
 425        let next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>> = Default::default();
 426        let last_input_timestamp = Rc::new(Cell::new(Instant::now()));
 427
 428        if fullscreen {
 429            platform_window.toggle_fullscreen();
 430        }
 431
 432        platform_window.on_close(Box::new({
 433            let mut cx = cx.to_async();
 434            move || {
 435                let _ = handle.update(&mut cx, |_, cx| cx.remove_window());
 436            }
 437        }));
 438        platform_window.on_request_frame(Box::new({
 439            let mut cx = cx.to_async();
 440            let dirty = dirty.clone();
 441            let active = active.clone();
 442            let needs_present = needs_present.clone();
 443            let next_frame_callbacks = next_frame_callbacks.clone();
 444            let last_input_timestamp = last_input_timestamp.clone();
 445            move || {
 446                let next_frame_callbacks = next_frame_callbacks.take();
 447                if !next_frame_callbacks.is_empty() {
 448                    handle
 449                        .update(&mut cx, |_, cx| {
 450                            for callback in next_frame_callbacks {
 451                                callback(cx);
 452                            }
 453                        })
 454                        .log_err();
 455                }
 456
 457                // Keep presenting the current scene for 1 extra second since the
 458                // last input to prevent the display from underclocking the refresh rate.
 459                let needs_present = needs_present.get()
 460                    || (active.get()
 461                        && last_input_timestamp.get().elapsed() < Duration::from_secs(1));
 462
 463                if dirty.get() {
 464                    measure("frame duration", || {
 465                        handle
 466                            .update(&mut cx, |_, cx| {
 467                                cx.draw();
 468                                cx.present();
 469                            })
 470                            .log_err();
 471                    })
 472                } else if needs_present {
 473                    handle.update(&mut cx, |_, cx| cx.present()).log_err();
 474                }
 475            }
 476        }));
 477        platform_window.on_resize(Box::new({
 478            let mut cx = cx.to_async();
 479            move |_, _| {
 480                handle
 481                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 482                    .log_err();
 483            }
 484        }));
 485        platform_window.on_moved(Box::new({
 486            let mut cx = cx.to_async();
 487            move || {
 488                handle
 489                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 490                    .log_err();
 491            }
 492        }));
 493        platform_window.on_appearance_changed(Box::new({
 494            let mut cx = cx.to_async();
 495            move || {
 496                handle
 497                    .update(&mut cx, |_, cx| cx.appearance_changed())
 498                    .log_err();
 499            }
 500        }));
 501        platform_window.on_active_status_change(Box::new({
 502            let mut cx = cx.to_async();
 503            move |active| {
 504                handle
 505                    .update(&mut cx, |_, cx| {
 506                        cx.window.active.set(active);
 507                        cx.window
 508                            .activation_observers
 509                            .clone()
 510                            .retain(&(), |callback| callback(cx));
 511                        cx.refresh();
 512                    })
 513                    .log_err();
 514            }
 515        }));
 516
 517        platform_window.on_input({
 518            let mut cx = cx.to_async();
 519            Box::new(move |event| {
 520                handle
 521                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 522                    .log_err()
 523                    .unwrap_or(DispatchEventResult::default())
 524            })
 525        });
 526
 527        Window {
 528            handle,
 529            removed: false,
 530            platform_window,
 531            display_id,
 532            sprite_atlas,
 533            text_system,
 534            rem_size: px(16.),
 535            viewport_size: content_size,
 536            layout_engine: Some(TaffyLayoutEngine::new()),
 537            root_view: None,
 538            element_id_stack: GlobalElementId::default(),
 539            text_style_stack: Vec::new(),
 540            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 541            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 542            next_frame_callbacks,
 543            next_hitbox_id: HitboxId::default(),
 544            dirty_views: FxHashSet::default(),
 545            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 546            focus_listeners: SubscriberSet::new(),
 547            focus_lost_listeners: SubscriberSet::new(),
 548            default_prevented: true,
 549            mouse_position,
 550            mouse_hit_test: HitTest::default(),
 551            modifiers,
 552            scale_factor,
 553            bounds_observers: SubscriberSet::new(),
 554            appearance,
 555            appearance_observers: SubscriberSet::new(),
 556            active,
 557            dirty,
 558            needs_present,
 559            last_input_timestamp,
 560            refreshing: false,
 561            draw_phase: DrawPhase::None,
 562            activation_observers: SubscriberSet::new(),
 563            focus: None,
 564            focus_enabled: true,
 565            pending_input: None,
 566            prompt: None,
 567        }
 568    }
 569    fn new_focus_listener(
 570        &mut self,
 571        value: AnyWindowFocusListener,
 572    ) -> (Subscription, impl FnOnce()) {
 573        self.focus_listeners.insert((), value)
 574    }
 575}
 576
 577#[derive(Clone, Debug, Default, PartialEq, Eq)]
 578pub(crate) struct DispatchEventResult {
 579    pub propagate: bool,
 580    pub default_prevented: bool,
 581}
 582
 583/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 584/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 585/// to leave room to support more complex shapes in the future.
 586#[derive(Clone, Debug, Default, PartialEq, Eq)]
 587#[repr(C)]
 588pub struct ContentMask<P: Clone + Default + Debug> {
 589    /// The bounds
 590    pub bounds: Bounds<P>,
 591}
 592
 593impl ContentMask<Pixels> {
 594    /// Scale the content mask's pixel units by the given scaling factor.
 595    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 596        ContentMask {
 597            bounds: self.bounds.scale(factor),
 598        }
 599    }
 600
 601    /// Intersect the content mask with the given content mask.
 602    pub fn intersect(&self, other: &Self) -> Self {
 603        let bounds = self.bounds.intersect(&other.bounds);
 604        ContentMask { bounds }
 605    }
 606}
 607
 608/// Provides access to application state in the context of a single window. Derefs
 609/// to an [`AppContext`], so you can also pass a [`WindowContext`] to any method that takes
 610/// an [`AppContext`] and call any [`AppContext`] methods.
 611pub struct WindowContext<'a> {
 612    pub(crate) app: &'a mut AppContext,
 613    pub(crate) window: &'a mut Window,
 614}
 615
 616impl<'a> WindowContext<'a> {
 617    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 618        Self { app, window }
 619    }
 620
 621    /// Obtain a handle to the window that belongs to this context.
 622    pub fn window_handle(&self) -> AnyWindowHandle {
 623        self.window.handle
 624    }
 625
 626    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 627    pub fn refresh(&mut self) {
 628        if self.window.draw_phase == DrawPhase::None {
 629            self.window.refreshing = true;
 630            self.window.dirty.set(true);
 631        }
 632    }
 633
 634    /// Close this window.
 635    pub fn remove_window(&mut self) {
 636        self.window.removed = true;
 637    }
 638
 639    /// Obtain a new [`FocusHandle`], which allows you to track and manipulate the keyboard focus
 640    /// for elements rendered within this window.
 641    pub fn focus_handle(&mut self) -> FocusHandle {
 642        FocusHandle::new(&self.window.focus_handles)
 643    }
 644
 645    /// Obtain the currently focused [`FocusHandle`]. If no elements are focused, returns `None`.
 646    pub fn focused(&self) -> Option<FocusHandle> {
 647        self.window
 648            .focus
 649            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 650    }
 651
 652    /// Move focus to the element associated with the given [`FocusHandle`].
 653    pub fn focus(&mut self, handle: &FocusHandle) {
 654        if !self.window.focus_enabled || self.window.focus == Some(handle.id) {
 655            return;
 656        }
 657
 658        self.window.focus = Some(handle.id);
 659        self.window
 660            .rendered_frame
 661            .dispatch_tree
 662            .clear_pending_keystrokes();
 663        self.refresh();
 664    }
 665
 666    /// Remove focus from all elements within this context's window.
 667    pub fn blur(&mut self) {
 668        if !self.window.focus_enabled {
 669            return;
 670        }
 671
 672        self.window.focus = None;
 673        self.refresh();
 674    }
 675
 676    /// Blur the window and don't allow anything in it to be focused again.
 677    pub fn disable_focus(&mut self) {
 678        self.blur();
 679        self.window.focus_enabled = false;
 680    }
 681
 682    /// Accessor for the text system.
 683    pub fn text_system(&self) -> &Arc<WindowTextSystem> {
 684        &self.window.text_system
 685    }
 686
 687    /// The current text style. Which is composed of all the style refinements provided to `with_text_style`.
 688    pub fn text_style(&self) -> TextStyle {
 689        let mut style = TextStyle::default();
 690        for refinement in &self.window.text_style_stack {
 691            style.refine(refinement);
 692        }
 693        style
 694    }
 695
 696    /// Check if the platform window is maximized
 697    /// On some platforms (namely Windows) this is different than the bounds being the size of the display
 698    pub fn is_maximized(&self) -> bool {
 699        self.window.platform_window.is_maximized()
 700    }
 701
 702    /// Dispatch the given action on the currently focused element.
 703    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 704        let focus_handle = self.focused();
 705
 706        let window = self.window.handle;
 707        self.app.defer(move |cx| {
 708            cx.propagate_event = true;
 709            window
 710                .update(cx, |_, cx| {
 711                    let node_id = focus_handle
 712                        .and_then(|handle| {
 713                            cx.window
 714                                .rendered_frame
 715                                .dispatch_tree
 716                                .focusable_node_id(handle.id)
 717                        })
 718                        .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 719
 720                    cx.dispatch_action_on_node(node_id, action.as_ref());
 721                })
 722                .log_err();
 723            if cx.propagate_event {
 724                cx.dispatch_global_action(action.as_ref());
 725            }
 726        })
 727    }
 728
 729    pub(crate) fn dispatch_keystroke_observers(
 730        &mut self,
 731        event: &dyn Any,
 732        action: Option<Box<dyn Action>>,
 733    ) {
 734        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 735            return;
 736        };
 737
 738        self.keystroke_observers
 739            .clone()
 740            .retain(&(), move |callback| {
 741                (callback)(
 742                    &KeystrokeEvent {
 743                        keystroke: key_down_event.keystroke.clone(),
 744                        action: action.as_ref().map(|action| action.boxed_clone()),
 745                    },
 746                    self,
 747                );
 748                true
 749            });
 750    }
 751
 752    pub(crate) fn clear_pending_keystrokes(&mut self) {
 753        self.window
 754            .rendered_frame
 755            .dispatch_tree
 756            .clear_pending_keystrokes();
 757        self.window
 758            .next_frame
 759            .dispatch_tree
 760            .clear_pending_keystrokes();
 761    }
 762
 763    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 764    /// that are currently on the stack to be returned to the app.
 765    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 766        let handle = self.window.handle;
 767        self.app.defer(move |cx| {
 768            handle.update(cx, |_, cx| f(cx)).ok();
 769        });
 770    }
 771
 772    /// Subscribe to events emitted by a model or view.
 773    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
 774    /// 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.
 775    pub fn subscribe<Emitter, E, Evt>(
 776        &mut self,
 777        entity: &E,
 778        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 779    ) -> Subscription
 780    where
 781        Emitter: EventEmitter<Evt>,
 782        E: Entity<Emitter>,
 783        Evt: 'static,
 784    {
 785        let entity_id = entity.entity_id();
 786        let entity = entity.downgrade();
 787        let window_handle = self.window.handle;
 788        self.app.new_subscription(
 789            entity_id,
 790            (
 791                TypeId::of::<Evt>(),
 792                Box::new(move |event, cx| {
 793                    window_handle
 794                        .update(cx, |_, cx| {
 795                            if let Some(handle) = E::upgrade_from(&entity) {
 796                                let event = event.downcast_ref().expect("invalid event type");
 797                                on_event(handle, event, cx);
 798                                true
 799                            } else {
 800                                false
 801                            }
 802                        })
 803                        .unwrap_or(false)
 804                }),
 805            ),
 806        )
 807    }
 808
 809    /// Creates an [`AsyncWindowContext`], which has a static lifetime and can be held across
 810    /// await points in async code.
 811    pub fn to_async(&self) -> AsyncWindowContext {
 812        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 813    }
 814
 815    /// Schedule the given closure to be run directly after the current frame is rendered.
 816    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 817        RefCell::borrow_mut(&self.window.next_frame_callbacks).push(Box::new(callback));
 818    }
 819
 820    /// Spawn the future returned by the given closure on the application thread pool.
 821    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 822    /// use within your future.
 823    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 824    where
 825        R: 'static,
 826        Fut: Future<Output = R> + 'static,
 827    {
 828        self.app
 829            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 830    }
 831
 832    /// Updates the global of the given type. The given closure is given simultaneous mutable
 833    /// access both to the global and the context.
 834    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 835    where
 836        G: Global,
 837    {
 838        let mut global = self.app.lease_global::<G>();
 839        let result = f(&mut global, self);
 840        self.app.end_global_lease(global);
 841        result
 842    }
 843
 844    fn window_bounds_changed(&mut self) {
 845        self.window.scale_factor = self.window.platform_window.scale_factor();
 846        self.window.viewport_size = self.window.platform_window.content_size();
 847        self.window.display_id = self.window.platform_window.display().id();
 848        self.refresh();
 849
 850        self.window
 851            .bounds_observers
 852            .clone()
 853            .retain(&(), |callback| callback(self));
 854    }
 855
 856    /// Returns the bounds of the current window in the global coordinate space, which could span across multiple displays.
 857    pub fn window_bounds(&self) -> Bounds<GlobalPixels> {
 858        self.window.platform_window.bounds()
 859    }
 860
 861    /// Retusn whether or not the window is currently fullscreen
 862    pub fn is_fullscreen(&self) -> bool {
 863        self.window.platform_window.is_fullscreen()
 864    }
 865
 866    fn appearance_changed(&mut self) {
 867        self.window.appearance = self.window.platform_window.appearance();
 868
 869        self.window
 870            .appearance_observers
 871            .clone()
 872            .retain(&(), |callback| callback(self));
 873    }
 874
 875    /// Returns the appearance of the current window.
 876    pub fn appearance(&self) -> WindowAppearance {
 877        self.window.appearance
 878    }
 879
 880    /// Returns the size of the drawable area within the window.
 881    pub fn viewport_size(&self) -> Size<Pixels> {
 882        self.window.viewport_size
 883    }
 884
 885    /// Returns whether this window is focused by the operating system (receiving key events).
 886    pub fn is_window_active(&self) -> bool {
 887        self.window.active.get()
 888    }
 889
 890    /// Toggle zoom on the window.
 891    pub fn zoom_window(&self) {
 892        self.window.platform_window.zoom();
 893    }
 894
 895    /// Updates the window's title at the platform level.
 896    pub fn set_window_title(&mut self, title: &str) {
 897        self.window.platform_window.set_title(title);
 898    }
 899
 900    /// Mark the window as dirty at the platform level.
 901    pub fn set_window_edited(&mut self, edited: bool) {
 902        self.window.platform_window.set_edited(edited);
 903    }
 904
 905    /// Determine the display on which the window is visible.
 906    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 907        self.platform
 908            .displays()
 909            .into_iter()
 910            .find(|display| display.id() == self.window.display_id)
 911    }
 912
 913    /// Show the platform character palette.
 914    pub fn show_character_palette(&self) {
 915        self.window.platform_window.show_character_palette();
 916    }
 917
 918    /// The scale factor of the display associated with the window. For example, it could
 919    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 920    /// be rendered as two pixels on screen.
 921    pub fn scale_factor(&self) -> f32 {
 922        self.window.scale_factor
 923    }
 924
 925    /// The size of an em for the base font of the application. Adjusting this value allows the
 926    /// UI to scale, just like zooming a web page.
 927    pub fn rem_size(&self) -> Pixels {
 928        self.window.rem_size
 929    }
 930
 931    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 932    /// UI to scale, just like zooming a web page.
 933    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 934        self.window.rem_size = rem_size.into();
 935    }
 936
 937    /// The line height associated with the current text style.
 938    pub fn line_height(&self) -> Pixels {
 939        let rem_size = self.rem_size();
 940        let text_style = self.text_style();
 941        text_style
 942            .line_height
 943            .to_pixels(text_style.font_size, rem_size)
 944    }
 945
 946    /// Call to prevent the default action of an event. Currently only used to prevent
 947    /// parent elements from becoming focused on mouse down.
 948    pub fn prevent_default(&mut self) {
 949        self.window.default_prevented = true;
 950    }
 951
 952    /// Obtain whether default has been prevented for the event currently being dispatched.
 953    pub fn default_prevented(&self) -> bool {
 954        self.window.default_prevented
 955    }
 956
 957    /// Determine whether the given action is available along the dispatch path to the currently focused element.
 958    pub fn is_action_available(&self, action: &dyn Action) -> bool {
 959        let target = self
 960            .focused()
 961            .and_then(|focused_handle| {
 962                self.window
 963                    .rendered_frame
 964                    .dispatch_tree
 965                    .focusable_node_id(focused_handle.id)
 966            })
 967            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
 968        self.window
 969            .rendered_frame
 970            .dispatch_tree
 971            .is_action_available(action, target)
 972    }
 973
 974    /// The position of the mouse relative to the window.
 975    pub fn mouse_position(&self) -> Point<Pixels> {
 976        self.window.mouse_position
 977    }
 978
 979    /// The current state of the keyboard's modifiers
 980    pub fn modifiers(&self) -> Modifiers {
 981        self.window.modifiers
 982    }
 983
 984    /// Produces a new frame and assigns it to `rendered_frame`. To actually show
 985    /// the contents of the new [Scene], use [present].
 986    #[profiling::function]
 987    pub fn draw(&mut self) {
 988        self.window.dirty.set(false);
 989
 990        // Restore the previously-used input handler.
 991        if let Some(input_handler) = self.window.platform_window.take_input_handler() {
 992            self.window
 993                .rendered_frame
 994                .input_handlers
 995                .push(Some(input_handler));
 996        }
 997
 998        self.with_element_context(|cx| cx.draw_roots());
 999        self.window.dirty_views.clear();
1000
1001        self.window
1002            .next_frame
1003            .dispatch_tree
1004            .preserve_pending_keystrokes(
1005                &mut self.window.rendered_frame.dispatch_tree,
1006                self.window.focus,
1007            );
1008        self.window.next_frame.focus = self.window.focus;
1009        self.window.next_frame.window_active = self.window.active.get();
1010
1011        // Register requested input handler with the platform window.
1012        if let Some(input_handler) = self.window.next_frame.input_handlers.pop() {
1013            self.window
1014                .platform_window
1015                .set_input_handler(input_handler.unwrap());
1016        }
1017
1018        self.window.layout_engine.as_mut().unwrap().clear();
1019        self.text_system().finish_frame();
1020        self.window
1021            .next_frame
1022            .finish(&mut self.window.rendered_frame);
1023        ELEMENT_ARENA.with_borrow_mut(|element_arena| {
1024            let percentage = (element_arena.len() as f32 / element_arena.capacity() as f32) * 100.;
1025            if percentage >= 80. {
1026                log::warn!("elevated element arena occupation: {}.", percentage);
1027            }
1028            element_arena.clear();
1029        });
1030
1031        self.window.draw_phase = DrawPhase::Focus;
1032        let previous_focus_path = self.window.rendered_frame.focus_path();
1033        let previous_window_active = self.window.rendered_frame.window_active;
1034        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1035        self.window.next_frame.clear();
1036        let current_focus_path = self.window.rendered_frame.focus_path();
1037        let current_window_active = self.window.rendered_frame.window_active;
1038
1039        if previous_focus_path != current_focus_path
1040            || previous_window_active != current_window_active
1041        {
1042            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1043                self.window
1044                    .focus_lost_listeners
1045                    .clone()
1046                    .retain(&(), |listener| listener(self));
1047            }
1048
1049            let event = FocusEvent {
1050                previous_focus_path: if previous_window_active {
1051                    previous_focus_path
1052                } else {
1053                    Default::default()
1054                },
1055                current_focus_path: if current_window_active {
1056                    current_focus_path
1057                } else {
1058                    Default::default()
1059                },
1060            };
1061            self.window
1062                .focus_listeners
1063                .clone()
1064                .retain(&(), |listener| listener(&event, self));
1065        }
1066
1067        self.reset_cursor_style();
1068        self.window.refreshing = false;
1069        self.window.draw_phase = DrawPhase::None;
1070        self.window.needs_present.set(true);
1071    }
1072
1073    #[profiling::function]
1074    fn present(&self) {
1075        self.window
1076            .platform_window
1077            .draw(&self.window.rendered_frame.scene);
1078        self.window.needs_present.set(false);
1079        profiling::finish_frame!();
1080    }
1081
1082    fn reset_cursor_style(&self) {
1083        // Set the cursor only if we're the active window.
1084        if self.is_window_active() {
1085            let style = self
1086                .window
1087                .rendered_frame
1088                .cursor_styles
1089                .iter()
1090                .rev()
1091                .find(|request| request.hitbox_id.is_hovered(self))
1092                .map(|request| request.style)
1093                .unwrap_or(CursorStyle::Arrow);
1094            self.platform.set_cursor_style(style);
1095        }
1096    }
1097
1098    /// Dispatch a given keystroke as though the user had typed it.
1099    /// You can create a keystroke with Keystroke::parse("").
1100    pub fn dispatch_keystroke(&mut self, keystroke: Keystroke) -> bool {
1101        let keystroke = keystroke.with_simulated_ime();
1102        let result = self.dispatch_event(PlatformInput::KeyDown(KeyDownEvent {
1103            keystroke: keystroke.clone(),
1104            is_held: false,
1105        }));
1106        if !result.propagate {
1107            return true;
1108        }
1109
1110        if let Some(input) = keystroke.ime_key {
1111            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1112                input_handler.dispatch_input(&input, self);
1113                self.window.platform_window.set_input_handler(input_handler);
1114                return true;
1115            }
1116        }
1117
1118        false
1119    }
1120
1121    /// Represent this action as a key binding string, to display in the UI.
1122    pub fn keystroke_text_for(&self, action: &dyn Action) -> String {
1123        self.bindings_for_action(action)
1124            .into_iter()
1125            .next()
1126            .map(|binding| {
1127                binding
1128                    .keystrokes()
1129                    .iter()
1130                    .map(ToString::to_string)
1131                    .collect::<Vec<_>>()
1132                    .join(" ")
1133            })
1134            .unwrap_or_else(|| action.name().to_string())
1135    }
1136
1137    /// Dispatch a mouse or keyboard event on the window.
1138    #[profiling::function]
1139    pub fn dispatch_event(&mut self, event: PlatformInput) -> DispatchEventResult {
1140        self.window.last_input_timestamp.set(Instant::now());
1141        // Handlers may set this to false by calling `stop_propagation`.
1142        self.app.propagate_event = true;
1143        // Handlers may set this to true by calling `prevent_default`.
1144        self.window.default_prevented = false;
1145
1146        let event = match event {
1147            // Track the mouse position with our own state, since accessing the platform
1148            // API for the mouse position can only occur on the main thread.
1149            PlatformInput::MouseMove(mouse_move) => {
1150                self.window.mouse_position = mouse_move.position;
1151                self.window.modifiers = mouse_move.modifiers;
1152                PlatformInput::MouseMove(mouse_move)
1153            }
1154            PlatformInput::MouseDown(mouse_down) => {
1155                self.window.mouse_position = mouse_down.position;
1156                self.window.modifiers = mouse_down.modifiers;
1157                PlatformInput::MouseDown(mouse_down)
1158            }
1159            PlatformInput::MouseUp(mouse_up) => {
1160                self.window.mouse_position = mouse_up.position;
1161                self.window.modifiers = mouse_up.modifiers;
1162                PlatformInput::MouseUp(mouse_up)
1163            }
1164            PlatformInput::MouseExited(mouse_exited) => {
1165                self.window.modifiers = mouse_exited.modifiers;
1166                PlatformInput::MouseExited(mouse_exited)
1167            }
1168            PlatformInput::ModifiersChanged(modifiers_changed) => {
1169                self.window.modifiers = modifiers_changed.modifiers;
1170                PlatformInput::ModifiersChanged(modifiers_changed)
1171            }
1172            PlatformInput::ScrollWheel(scroll_wheel) => {
1173                self.window.mouse_position = scroll_wheel.position;
1174                self.window.modifiers = scroll_wheel.modifiers;
1175                PlatformInput::ScrollWheel(scroll_wheel)
1176            }
1177            // Translate dragging and dropping of external files from the operating system
1178            // to internal drag and drop events.
1179            PlatformInput::FileDrop(file_drop) => match file_drop {
1180                FileDropEvent::Entered { position, paths } => {
1181                    self.window.mouse_position = position;
1182                    if self.active_drag.is_none() {
1183                        self.active_drag = Some(AnyDrag {
1184                            value: Box::new(paths.clone()),
1185                            view: self.new_view(|_| paths).into(),
1186                            cursor_offset: position,
1187                        });
1188                    }
1189                    PlatformInput::MouseMove(MouseMoveEvent {
1190                        position,
1191                        pressed_button: Some(MouseButton::Left),
1192                        modifiers: Modifiers::default(),
1193                    })
1194                }
1195                FileDropEvent::Pending { position } => {
1196                    self.window.mouse_position = position;
1197                    PlatformInput::MouseMove(MouseMoveEvent {
1198                        position,
1199                        pressed_button: Some(MouseButton::Left),
1200                        modifiers: Modifiers::default(),
1201                    })
1202                }
1203                FileDropEvent::Submit { position } => {
1204                    self.activate(true);
1205                    self.window.mouse_position = position;
1206                    PlatformInput::MouseUp(MouseUpEvent {
1207                        button: MouseButton::Left,
1208                        position,
1209                        modifiers: Modifiers::default(),
1210                        click_count: 1,
1211                    })
1212                }
1213                FileDropEvent::Exited => {
1214                    self.active_drag.take();
1215                    PlatformInput::FileDrop(FileDropEvent::Exited)
1216                }
1217            },
1218            PlatformInput::KeyDown(_) | PlatformInput::KeyUp(_) => event,
1219        };
1220
1221        if let Some(any_mouse_event) = event.mouse_event() {
1222            self.dispatch_mouse_event(any_mouse_event);
1223        } else if let Some(any_key_event) = event.keyboard_event() {
1224            self.dispatch_key_event(any_key_event);
1225        }
1226
1227        DispatchEventResult {
1228            propagate: self.app.propagate_event,
1229            default_prevented: self.window.default_prevented,
1230        }
1231    }
1232
1233    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1234        let hit_test = self.window.rendered_frame.hit_test(self.mouse_position());
1235        if hit_test != self.window.mouse_hit_test {
1236            self.window.mouse_hit_test = hit_test;
1237            self.reset_cursor_style();
1238        }
1239
1240        let mut mouse_listeners = mem::take(&mut self.window.rendered_frame.mouse_listeners);
1241        self.with_element_context(|cx| {
1242            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1243            // special purposes, such as detecting events outside of a given Bounds.
1244            for listener in &mut mouse_listeners {
1245                let listener = listener.as_mut().unwrap();
1246                listener(event, DispatchPhase::Capture, cx);
1247                if !cx.app.propagate_event {
1248                    break;
1249                }
1250            }
1251
1252            // Bubble phase, where most normal handlers do their work.
1253            if cx.app.propagate_event {
1254                for listener in mouse_listeners.iter_mut().rev() {
1255                    let listener = listener.as_mut().unwrap();
1256                    listener(event, DispatchPhase::Bubble, cx);
1257                    if !cx.app.propagate_event {
1258                        break;
1259                    }
1260                }
1261            }
1262        });
1263        self.window.rendered_frame.mouse_listeners = mouse_listeners;
1264
1265        if self.app.propagate_event && self.has_active_drag() {
1266            if event.is::<MouseMoveEvent>() {
1267                // If this was a mouse move event, redraw the window so that the
1268                // active drag can follow the mouse cursor.
1269                self.refresh();
1270            } else if event.is::<MouseUpEvent>() {
1271                // If this was a mouse up event, cancel the active drag and redraw
1272                // the window.
1273                self.active_drag = None;
1274                self.refresh();
1275            }
1276        }
1277    }
1278
1279    fn dispatch_key_event(&mut self, event: &dyn Any) {
1280        if self.window.dirty.get() {
1281            self.draw();
1282        }
1283
1284        let node_id = self
1285            .window
1286            .focus
1287            .and_then(|focus_id| {
1288                self.window
1289                    .rendered_frame
1290                    .dispatch_tree
1291                    .focusable_node_id(focus_id)
1292            })
1293            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1294
1295        let dispatch_path = self
1296            .window
1297            .rendered_frame
1298            .dispatch_tree
1299            .dispatch_path(node_id);
1300
1301        if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1302            let KeymatchResult { bindings, pending } = self
1303                .window
1304                .rendered_frame
1305                .dispatch_tree
1306                .dispatch_key(&key_down_event.keystroke, &dispatch_path);
1307
1308            if pending {
1309                let mut currently_pending = self.window.pending_input.take().unwrap_or_default();
1310                if currently_pending.focus.is_some() && currently_pending.focus != self.window.focus
1311                {
1312                    currently_pending = PendingInput::default();
1313                }
1314                currently_pending.focus = self.window.focus;
1315                currently_pending
1316                    .keystrokes
1317                    .push(key_down_event.keystroke.clone());
1318                for binding in bindings {
1319                    currently_pending.bindings.push(binding);
1320                }
1321
1322                currently_pending.timer = Some(self.spawn(|mut cx| async move {
1323                    cx.background_executor.timer(Duration::from_secs(1)).await;
1324                    cx.update(move |cx| {
1325                        cx.clear_pending_keystrokes();
1326                        let Some(currently_pending) = cx.window.pending_input.take() else {
1327                            return;
1328                        };
1329                        cx.replay_pending_input(currently_pending)
1330                    })
1331                    .log_err();
1332                }));
1333
1334                self.window.pending_input = Some(currently_pending);
1335
1336                self.propagate_event = false;
1337                return;
1338            } else if let Some(currently_pending) = self.window.pending_input.take() {
1339                if bindings
1340                    .iter()
1341                    .all(|binding| !currently_pending.used_by_binding(binding))
1342                {
1343                    self.replay_pending_input(currently_pending)
1344                }
1345            }
1346
1347            if !bindings.is_empty() {
1348                self.clear_pending_keystrokes();
1349            }
1350
1351            self.propagate_event = true;
1352            for binding in bindings {
1353                self.dispatch_action_on_node(node_id, binding.action.as_ref());
1354                if !self.propagate_event {
1355                    self.dispatch_keystroke_observers(event, Some(binding.action));
1356                    return;
1357                }
1358            }
1359        }
1360
1361        self.dispatch_key_down_up_event(event, &dispatch_path);
1362        if !self.propagate_event {
1363            return;
1364        }
1365
1366        self.dispatch_keystroke_observers(event, None);
1367    }
1368
1369    fn dispatch_key_down_up_event(
1370        &mut self,
1371        event: &dyn Any,
1372        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1373    ) {
1374        // Capture phase
1375        for node_id in dispatch_path {
1376            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1377
1378            for key_listener in node.key_listeners.clone() {
1379                self.with_element_context(|cx| {
1380                    key_listener(event, DispatchPhase::Capture, cx);
1381                });
1382                if !self.propagate_event {
1383                    return;
1384                }
1385            }
1386        }
1387
1388        // Bubble phase
1389        for node_id in dispatch_path.iter().rev() {
1390            // Handle low level key events
1391            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1392            for key_listener in node.key_listeners.clone() {
1393                self.with_element_context(|cx| {
1394                    key_listener(event, DispatchPhase::Bubble, cx);
1395                });
1396                if !self.propagate_event {
1397                    return;
1398                }
1399            }
1400        }
1401    }
1402
1403    /// Determine whether a potential multi-stroke key binding is in progress on this window.
1404    pub fn has_pending_keystrokes(&self) -> bool {
1405        self.window
1406            .rendered_frame
1407            .dispatch_tree
1408            .has_pending_keystrokes()
1409    }
1410
1411    fn replay_pending_input(&mut self, currently_pending: PendingInput) {
1412        let node_id = self
1413            .window
1414            .focus
1415            .and_then(|focus_id| {
1416                self.window
1417                    .rendered_frame
1418                    .dispatch_tree
1419                    .focusable_node_id(focus_id)
1420            })
1421            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1422
1423        if self.window.focus != currently_pending.focus {
1424            return;
1425        }
1426
1427        let input = currently_pending.input();
1428
1429        self.propagate_event = true;
1430        for binding in currently_pending.bindings {
1431            self.dispatch_action_on_node(node_id, binding.action.as_ref());
1432            if !self.propagate_event {
1433                return;
1434            }
1435        }
1436
1437        let dispatch_path = self
1438            .window
1439            .rendered_frame
1440            .dispatch_tree
1441            .dispatch_path(node_id);
1442
1443        for keystroke in currently_pending.keystrokes {
1444            let event = KeyDownEvent {
1445                keystroke,
1446                is_held: false,
1447            };
1448
1449            self.dispatch_key_down_up_event(&event, &dispatch_path);
1450            if !self.propagate_event {
1451                return;
1452            }
1453        }
1454
1455        if !input.is_empty() {
1456            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1457                input_handler.dispatch_input(&input, self);
1458                self.window.platform_window.set_input_handler(input_handler)
1459            }
1460        }
1461    }
1462
1463    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: &dyn Action) {
1464        let dispatch_path = self
1465            .window
1466            .rendered_frame
1467            .dispatch_tree
1468            .dispatch_path(node_id);
1469
1470        // Capture phase
1471        for node_id in &dispatch_path {
1472            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1473            for DispatchActionListener {
1474                action_type,
1475                listener,
1476            } in node.action_listeners.clone()
1477            {
1478                let any_action = action.as_any();
1479                if action_type == any_action.type_id() {
1480                    self.with_element_context(|cx| {
1481                        listener(any_action, DispatchPhase::Capture, cx);
1482                    });
1483
1484                    if !self.propagate_event {
1485                        return;
1486                    }
1487                }
1488            }
1489        }
1490        // Bubble phase
1491        for node_id in dispatch_path.iter().rev() {
1492            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1493            for DispatchActionListener {
1494                action_type,
1495                listener,
1496            } in node.action_listeners.clone()
1497            {
1498                let any_action = action.as_any();
1499                if action_type == any_action.type_id() {
1500                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1501
1502                    self.with_element_context(|cx| {
1503                        listener(any_action, DispatchPhase::Bubble, cx);
1504                    });
1505
1506                    if !self.propagate_event {
1507                        return;
1508                    }
1509                }
1510            }
1511        }
1512    }
1513
1514    /// Register the given handler to be invoked whenever the global of the given type
1515    /// is updated.
1516    pub fn observe_global<G: Global>(
1517        &mut self,
1518        f: impl Fn(&mut WindowContext<'_>) + 'static,
1519    ) -> Subscription {
1520        let window_handle = self.window.handle;
1521        let (subscription, activate) = self.global_observers.insert(
1522            TypeId::of::<G>(),
1523            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1524        );
1525        self.app.defer(move |_| activate());
1526        subscription
1527    }
1528
1529    /// Focus the current window and bring it to the foreground at the platform level.
1530    pub fn activate_window(&self) {
1531        self.window.platform_window.activate();
1532    }
1533
1534    /// Minimize the current window at the platform level.
1535    pub fn minimize_window(&self) {
1536        self.window.platform_window.minimize();
1537    }
1538
1539    /// Toggle full screen status on the current window at the platform level.
1540    pub fn toggle_fullscreen(&self) {
1541        self.window.platform_window.toggle_fullscreen();
1542    }
1543
1544    /// Present a platform dialog.
1545    /// The provided message will be presented, along with buttons for each answer.
1546    /// When a button is clicked, the returned Receiver will receive the index of the clicked button.
1547    pub fn prompt(
1548        &mut self,
1549        level: PromptLevel,
1550        message: &str,
1551        detail: Option<&str>,
1552        answers: &[&str],
1553    ) -> oneshot::Receiver<usize> {
1554        let prompt_builder = self.app.prompt_builder.take();
1555        let Some(prompt_builder) = prompt_builder else {
1556            unreachable!("Re-entrant window prompting is not supported by GPUI");
1557        };
1558
1559        let receiver = match &prompt_builder {
1560            PromptBuilder::Default => self
1561                .window
1562                .platform_window
1563                .prompt(level, message, detail, answers)
1564                .unwrap_or_else(|| {
1565                    self.build_custom_prompt(&prompt_builder, level, message, detail, answers)
1566                }),
1567            PromptBuilder::Custom(_) => {
1568                self.build_custom_prompt(&prompt_builder, level, message, detail, answers)
1569            }
1570        };
1571
1572        self.app.prompt_builder = Some(prompt_builder);
1573
1574        receiver
1575    }
1576
1577    fn build_custom_prompt(
1578        &mut self,
1579        prompt_builder: &PromptBuilder,
1580        level: PromptLevel,
1581        message: &str,
1582        detail: Option<&str>,
1583        answers: &[&str],
1584    ) -> oneshot::Receiver<usize> {
1585        let (sender, receiver) = oneshot::channel();
1586        let handle = PromptHandle::new(sender);
1587        let handle = (prompt_builder)(level, message, detail, answers, handle, self);
1588        self.window.prompt = Some(handle);
1589        receiver
1590    }
1591
1592    /// Returns all available actions for the focused element.
1593    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1594        let node_id = self
1595            .window
1596            .focus
1597            .and_then(|focus_id| {
1598                self.window
1599                    .rendered_frame
1600                    .dispatch_tree
1601                    .focusable_node_id(focus_id)
1602            })
1603            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1604
1605        let mut actions = self
1606            .window
1607            .rendered_frame
1608            .dispatch_tree
1609            .available_actions(node_id);
1610        for action_type in self.global_action_listeners.keys() {
1611            if let Err(ix) = actions.binary_search_by_key(action_type, |a| a.as_any().type_id()) {
1612                let action = self.actions.build_action_type(action_type).ok();
1613                if let Some(action) = action {
1614                    actions.insert(ix, action);
1615                }
1616            }
1617        }
1618        actions
1619    }
1620
1621    /// Returns key bindings that invoke the given action on the currently focused element.
1622    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1623        self.window
1624            .rendered_frame
1625            .dispatch_tree
1626            .bindings_for_action(
1627                action,
1628                &self.window.rendered_frame.dispatch_tree.context_stack,
1629            )
1630    }
1631
1632    /// Returns any bindings that would invoke the given action on the given focus handle if it were focused.
1633    pub fn bindings_for_action_in(
1634        &self,
1635        action: &dyn Action,
1636        focus_handle: &FocusHandle,
1637    ) -> Vec<KeyBinding> {
1638        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1639
1640        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1641            return vec![];
1642        };
1643        let context_stack: Vec<_> = dispatch_tree
1644            .dispatch_path(node_id)
1645            .into_iter()
1646            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1647            .collect();
1648        dispatch_tree.bindings_for_action(action, &context_stack)
1649    }
1650
1651    /// Returns a generic event listener that invokes the given listener with the view and context associated with the given view handle.
1652    pub fn listener_for<V: Render, E>(
1653        &self,
1654        view: &View<V>,
1655        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1656    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1657        let view = view.downgrade();
1658        move |e: &E, cx: &mut WindowContext| {
1659            view.update(cx, |view, cx| f(view, e, cx)).ok();
1660        }
1661    }
1662
1663    /// Returns a generic handler that invokes the given handler with the view and context associated with the given view handle.
1664    pub fn handler_for<V: Render>(
1665        &self,
1666        view: &View<V>,
1667        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1668    ) -> impl Fn(&mut WindowContext) {
1669        let view = view.downgrade();
1670        move |cx: &mut WindowContext| {
1671            view.update(cx, |view, cx| f(view, cx)).ok();
1672        }
1673    }
1674
1675    /// Register a callback that can interrupt the closing of the current window based the returned boolean.
1676    /// If the callback returns false, the window won't be closed.
1677    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1678        let mut this = self.to_async();
1679        self.window
1680            .platform_window
1681            .on_should_close(Box::new(move || this.update(|cx| f(cx)).unwrap_or(true)))
1682    }
1683
1684    /// Register an action listener on the window for the next frame. The type of action
1685    /// is determined by the first parameter of the given listener. When the next frame is rendered
1686    /// the listener will be cleared.
1687    ///
1688    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
1689    /// a specific need to register a global listener.
1690    pub fn on_action(
1691        &mut self,
1692        action_type: TypeId,
1693        listener: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
1694    ) {
1695        self.window
1696            .next_frame
1697            .dispatch_tree
1698            .on_action(action_type, Rc::new(listener));
1699    }
1700}
1701
1702#[cfg(target_os = "windows")]
1703impl WindowContext<'_> {
1704    /// Returns the raw HWND handle for the window.
1705    pub fn get_raw_handle(&self) -> windows::Win32::Foundation::HWND {
1706        self.window.platform_window.get_raw_handle()
1707    }
1708}
1709
1710impl Context for WindowContext<'_> {
1711    type Result<T> = T;
1712
1713    fn new_model<T>(&mut self, build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T) -> Model<T>
1714    where
1715        T: 'static,
1716    {
1717        let slot = self.app.entities.reserve();
1718        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1719        self.entities.insert(slot, model)
1720    }
1721
1722    fn update_model<T: 'static, R>(
1723        &mut self,
1724        model: &Model<T>,
1725        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1726    ) -> R {
1727        let mut entity = self.entities.lease(model);
1728        let result = update(
1729            &mut *entity,
1730            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1731        );
1732        self.entities.end_lease(entity);
1733        result
1734    }
1735
1736    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1737    where
1738        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1739    {
1740        if window == self.window.handle {
1741            let root_view = self.window.root_view.clone().unwrap();
1742            Ok(update(root_view, self))
1743        } else {
1744            window.update(self.app, update)
1745        }
1746    }
1747
1748    fn read_model<T, R>(
1749        &self,
1750        handle: &Model<T>,
1751        read: impl FnOnce(&T, &AppContext) -> R,
1752    ) -> Self::Result<R>
1753    where
1754        T: 'static,
1755    {
1756        let entity = self.entities.read(handle);
1757        read(entity, &*self.app)
1758    }
1759
1760    fn read_window<T, R>(
1761        &self,
1762        window: &WindowHandle<T>,
1763        read: impl FnOnce(View<T>, &AppContext) -> R,
1764    ) -> Result<R>
1765    where
1766        T: 'static,
1767    {
1768        if window.any_handle == self.window.handle {
1769            let root_view = self
1770                .window
1771                .root_view
1772                .clone()
1773                .unwrap()
1774                .downcast::<T>()
1775                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1776            Ok(read(root_view, self))
1777        } else {
1778            self.app.read_window(window, read)
1779        }
1780    }
1781}
1782
1783impl VisualContext for WindowContext<'_> {
1784    fn new_view<V>(
1785        &mut self,
1786        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1787    ) -> Self::Result<View<V>>
1788    where
1789        V: 'static + Render,
1790    {
1791        let slot = self.app.entities.reserve();
1792        let view = View {
1793            model: slot.clone(),
1794        };
1795        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1796        let entity = build_view_state(&mut cx);
1797        cx.entities.insert(slot, entity);
1798
1799        // Non-generic part to avoid leaking SubscriberSet to invokers of `new_view`.
1800        fn notify_observers(cx: &mut WindowContext, tid: TypeId, view: AnyView) {
1801            cx.new_view_observers.clone().retain(&tid, |observer| {
1802                let any_view = view.clone();
1803                (observer)(any_view, cx);
1804                true
1805            });
1806        }
1807        notify_observers(self, TypeId::of::<V>(), AnyView::from(view.clone()));
1808
1809        view
1810    }
1811
1812    /// Updates the given view. Prefer calling [`View::update`] instead, which calls this method.
1813    fn update_view<T: 'static, R>(
1814        &mut self,
1815        view: &View<T>,
1816        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1817    ) -> Self::Result<R> {
1818        let mut lease = self.app.entities.lease(&view.model);
1819        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, view);
1820        let result = update(&mut *lease, &mut cx);
1821        cx.app.entities.end_lease(lease);
1822        result
1823    }
1824
1825    fn replace_root_view<V>(
1826        &mut self,
1827        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1828    ) -> Self::Result<View<V>>
1829    where
1830        V: 'static + Render,
1831    {
1832        let view = self.new_view(build_view);
1833        self.window.root_view = Some(view.clone().into());
1834        self.refresh();
1835        view
1836    }
1837
1838    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1839        self.update_view(view, |view, cx| {
1840            view.focus_handle(cx).clone().focus(cx);
1841        })
1842    }
1843
1844    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1845    where
1846        V: ManagedView,
1847    {
1848        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1849    }
1850}
1851
1852impl<'a> std::ops::Deref for WindowContext<'a> {
1853    type Target = AppContext;
1854
1855    fn deref(&self) -> &Self::Target {
1856        self.app
1857    }
1858}
1859
1860impl<'a> std::ops::DerefMut for WindowContext<'a> {
1861    fn deref_mut(&mut self) -> &mut Self::Target {
1862        self.app
1863    }
1864}
1865
1866impl<'a> Borrow<AppContext> for WindowContext<'a> {
1867    fn borrow(&self) -> &AppContext {
1868        self.app
1869    }
1870}
1871
1872impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1873    fn borrow_mut(&mut self) -> &mut AppContext {
1874        self.app
1875    }
1876}
1877
1878/// This trait contains functionality that is shared across [`ViewContext`] and [`WindowContext`]
1879pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1880    #[doc(hidden)]
1881    fn app_mut(&mut self) -> &mut AppContext {
1882        self.borrow_mut()
1883    }
1884
1885    #[doc(hidden)]
1886    fn app(&self) -> &AppContext {
1887        self.borrow()
1888    }
1889
1890    #[doc(hidden)]
1891    fn window(&self) -> &Window {
1892        self.borrow()
1893    }
1894
1895    #[doc(hidden)]
1896    fn window_mut(&mut self) -> &mut Window {
1897        self.borrow_mut()
1898    }
1899}
1900
1901impl Borrow<Window> for WindowContext<'_> {
1902    fn borrow(&self) -> &Window {
1903        self.window
1904    }
1905}
1906
1907impl BorrowMut<Window> for WindowContext<'_> {
1908    fn borrow_mut(&mut self) -> &mut Window {
1909        self.window
1910    }
1911}
1912
1913impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
1914
1915/// Provides access to application state that is specialized for a particular [`View`].
1916/// Allows you to interact with focus, emit events, etc.
1917/// ViewContext also derefs to [`WindowContext`], giving you access to all of its methods as well.
1918/// When you call [`View::update`], you're passed a `&mut V` and an `&mut ViewContext<V>`.
1919pub struct ViewContext<'a, V> {
1920    window_cx: WindowContext<'a>,
1921    view: &'a View<V>,
1922}
1923
1924impl<V> Borrow<AppContext> for ViewContext<'_, V> {
1925    fn borrow(&self) -> &AppContext {
1926        &*self.window_cx.app
1927    }
1928}
1929
1930impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
1931    fn borrow_mut(&mut self) -> &mut AppContext {
1932        &mut *self.window_cx.app
1933    }
1934}
1935
1936impl<V> Borrow<Window> for ViewContext<'_, V> {
1937    fn borrow(&self) -> &Window {
1938        &*self.window_cx.window
1939    }
1940}
1941
1942impl<V> BorrowMut<Window> for ViewContext<'_, V> {
1943    fn borrow_mut(&mut self) -> &mut Window {
1944        &mut *self.window_cx.window
1945    }
1946}
1947
1948impl<'a, V: 'static> ViewContext<'a, V> {
1949    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
1950        Self {
1951            window_cx: WindowContext::new(app, window),
1952            view,
1953        }
1954    }
1955
1956    /// Get the entity_id of this view.
1957    pub fn entity_id(&self) -> EntityId {
1958        self.view.entity_id()
1959    }
1960
1961    /// Get the view pointer underlying this context.
1962    pub fn view(&self) -> &View<V> {
1963        self.view
1964    }
1965
1966    /// Get the model underlying this view.
1967    pub fn model(&self) -> &Model<V> {
1968        &self.view.model
1969    }
1970
1971    /// Access the underlying window context.
1972    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
1973        &mut self.window_cx
1974    }
1975
1976    /// Sets a given callback to be run on the next frame.
1977    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
1978    where
1979        V: 'static,
1980    {
1981        let view = self.view().clone();
1982        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
1983    }
1984
1985    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
1986    /// that are currently on the stack to be returned to the app.
1987    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
1988        let view = self.view().downgrade();
1989        self.window_cx.defer(move |cx| {
1990            view.update(cx, f).ok();
1991        });
1992    }
1993
1994    /// Observe another model or view for changes to its state, as tracked by [`ModelContext::notify`].
1995    pub fn observe<V2, E>(
1996        &mut self,
1997        entity: &E,
1998        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
1999    ) -> Subscription
2000    where
2001        V2: 'static,
2002        V: 'static,
2003        E: Entity<V2>,
2004    {
2005        let view = self.view().downgrade();
2006        let entity_id = entity.entity_id();
2007        let entity = entity.downgrade();
2008        let window_handle = self.window.handle;
2009        self.app.new_observer(
2010            entity_id,
2011            Box::new(move |cx| {
2012                window_handle
2013                    .update(cx, |_, cx| {
2014                        if let Some(handle) = E::upgrade_from(&entity) {
2015                            view.update(cx, |this, cx| on_notify(this, handle, cx))
2016                                .is_ok()
2017                        } else {
2018                            false
2019                        }
2020                    })
2021                    .unwrap_or(false)
2022            }),
2023        )
2024    }
2025
2026    /// Subscribe to events emitted by another model or view.
2027    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
2028    /// 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.
2029    pub fn subscribe<V2, E, Evt>(
2030        &mut self,
2031        entity: &E,
2032        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2033    ) -> Subscription
2034    where
2035        V2: EventEmitter<Evt>,
2036        E: Entity<V2>,
2037        Evt: 'static,
2038    {
2039        let view = self.view().downgrade();
2040        let entity_id = entity.entity_id();
2041        let handle = entity.downgrade();
2042        let window_handle = self.window.handle;
2043        self.app.new_subscription(
2044            entity_id,
2045            (
2046                TypeId::of::<Evt>(),
2047                Box::new(move |event, cx| {
2048                    window_handle
2049                        .update(cx, |_, cx| {
2050                            if let Some(handle) = E::upgrade_from(&handle) {
2051                                let event = event.downcast_ref().expect("invalid event type");
2052                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2053                                    .is_ok()
2054                            } else {
2055                                false
2056                            }
2057                        })
2058                        .unwrap_or(false)
2059                }),
2060            ),
2061        )
2062    }
2063
2064    /// Register a callback to be invoked when the view is released.
2065    ///
2066    /// The callback receives a handle to the view's window. This handle may be
2067    /// invalid, if the window was closed before the view was released.
2068    pub fn on_release(
2069        &mut self,
2070        on_release: impl FnOnce(&mut V, AnyWindowHandle, &mut AppContext) + 'static,
2071    ) -> Subscription {
2072        let window_handle = self.window.handle;
2073        let (subscription, activate) = self.app.release_listeners.insert(
2074            self.view.model.entity_id,
2075            Box::new(move |this, cx| {
2076                let this = this.downcast_mut().expect("invalid entity type");
2077                on_release(this, window_handle, cx)
2078            }),
2079        );
2080        activate();
2081        subscription
2082    }
2083
2084    /// Register a callback to be invoked when the given Model or View is released.
2085    pub fn observe_release<V2, E>(
2086        &mut self,
2087        entity: &E,
2088        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2089    ) -> Subscription
2090    where
2091        V: 'static,
2092        V2: 'static,
2093        E: Entity<V2>,
2094    {
2095        let view = self.view().downgrade();
2096        let entity_id = entity.entity_id();
2097        let window_handle = self.window.handle;
2098        let (subscription, activate) = self.app.release_listeners.insert(
2099            entity_id,
2100            Box::new(move |entity, cx| {
2101                let entity = entity.downcast_mut().expect("invalid entity type");
2102                let _ = window_handle.update(cx, |_, cx| {
2103                    view.update(cx, |this, cx| on_release(this, entity, cx))
2104                });
2105            }),
2106        );
2107        activate();
2108        subscription
2109    }
2110
2111    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
2112    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
2113    pub fn notify(&mut self) {
2114        for view_id in self
2115            .window
2116            .rendered_frame
2117            .dispatch_tree
2118            .view_path(self.view.entity_id())
2119            .into_iter()
2120            .rev()
2121        {
2122            if !self.window.dirty_views.insert(view_id) {
2123                break;
2124            }
2125        }
2126
2127        if self.window.draw_phase == DrawPhase::None {
2128            self.window_cx.window.dirty.set(true);
2129            self.window_cx.app.push_effect(Effect::Notify {
2130                emitter: self.view.model.entity_id,
2131            });
2132        }
2133    }
2134
2135    /// Register a callback to be invoked when the window is resized.
2136    pub fn observe_window_bounds(
2137        &mut self,
2138        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2139    ) -> Subscription {
2140        let view = self.view.downgrade();
2141        let (subscription, activate) = self.window.bounds_observers.insert(
2142            (),
2143            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2144        );
2145        activate();
2146        subscription
2147    }
2148
2149    /// Register a callback to be invoked when the window is activated or deactivated.
2150    pub fn observe_window_activation(
2151        &mut self,
2152        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2153    ) -> Subscription {
2154        let view = self.view.downgrade();
2155        let (subscription, activate) = self.window.activation_observers.insert(
2156            (),
2157            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2158        );
2159        activate();
2160        subscription
2161    }
2162
2163    /// Registers a callback to be invoked when the window appearance changes.
2164    pub fn observe_window_appearance(
2165        &mut self,
2166        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2167    ) -> Subscription {
2168        let view = self.view.downgrade();
2169        let (subscription, activate) = self.window.appearance_observers.insert(
2170            (),
2171            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2172        );
2173        activate();
2174        subscription
2175    }
2176
2177    /// Register a listener to be called when the given focus handle receives focus.
2178    /// Returns a subscription and persists until the subscription is dropped.
2179    pub fn on_focus(
2180        &mut self,
2181        handle: &FocusHandle,
2182        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2183    ) -> Subscription {
2184        let view = self.view.downgrade();
2185        let focus_id = handle.id;
2186        let (subscription, activate) =
2187            self.window.new_focus_listener(Box::new(move |event, cx| {
2188                view.update(cx, |view, cx| {
2189                    if event.previous_focus_path.last() != Some(&focus_id)
2190                        && event.current_focus_path.last() == Some(&focus_id)
2191                    {
2192                        listener(view, cx)
2193                    }
2194                })
2195                .is_ok()
2196            }));
2197        self.app.defer(|_| activate());
2198        subscription
2199    }
2200
2201    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2202    /// Returns a subscription and persists until the subscription is dropped.
2203    pub fn on_focus_in(
2204        &mut self,
2205        handle: &FocusHandle,
2206        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2207    ) -> Subscription {
2208        let view = self.view.downgrade();
2209        let focus_id = handle.id;
2210        let (subscription, activate) =
2211            self.window.new_focus_listener(Box::new(move |event, cx| {
2212                view.update(cx, |view, cx| {
2213                    if !event.previous_focus_path.contains(&focus_id)
2214                        && event.current_focus_path.contains(&focus_id)
2215                    {
2216                        listener(view, cx)
2217                    }
2218                })
2219                .is_ok()
2220            }));
2221        self.app.defer(move |_| activate());
2222        subscription
2223    }
2224
2225    /// Register a listener to be called when the given focus handle loses focus.
2226    /// Returns a subscription and persists until the subscription is dropped.
2227    pub fn on_blur(
2228        &mut self,
2229        handle: &FocusHandle,
2230        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2231    ) -> Subscription {
2232        let view = self.view.downgrade();
2233        let focus_id = handle.id;
2234        let (subscription, activate) =
2235            self.window.new_focus_listener(Box::new(move |event, cx| {
2236                view.update(cx, |view, cx| {
2237                    if event.previous_focus_path.last() == Some(&focus_id)
2238                        && event.current_focus_path.last() != Some(&focus_id)
2239                    {
2240                        listener(view, cx)
2241                    }
2242                })
2243                .is_ok()
2244            }));
2245        self.app.defer(move |_| activate());
2246        subscription
2247    }
2248
2249    /// Register a listener to be called when nothing in the window has focus.
2250    /// This typically happens when the node that was focused is removed from the tree,
2251    /// and this callback lets you chose a default place to restore the users focus.
2252    /// Returns a subscription and persists until the subscription is dropped.
2253    pub fn on_focus_lost(
2254        &mut self,
2255        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2256    ) -> Subscription {
2257        let view = self.view.downgrade();
2258        let (subscription, activate) = self.window.focus_lost_listeners.insert(
2259            (),
2260            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2261        );
2262        activate();
2263        subscription
2264    }
2265
2266    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2267    /// Returns a subscription and persists until the subscription is dropped.
2268    pub fn on_focus_out(
2269        &mut self,
2270        handle: &FocusHandle,
2271        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2272    ) -> Subscription {
2273        let view = self.view.downgrade();
2274        let focus_id = handle.id;
2275        let (subscription, activate) =
2276            self.window.new_focus_listener(Box::new(move |event, cx| {
2277                view.update(cx, |view, cx| {
2278                    if event.previous_focus_path.contains(&focus_id)
2279                        && !event.current_focus_path.contains(&focus_id)
2280                    {
2281                        listener(view, cx)
2282                    }
2283                })
2284                .is_ok()
2285            }));
2286        self.app.defer(move |_| activate());
2287        subscription
2288    }
2289
2290    /// Schedule a future to be run asynchronously.
2291    /// The given callback is invoked with a [`WeakView<V>`] to avoid leaking the view for a long-running process.
2292    /// It's also given an [`AsyncWindowContext`], which can be used to access the state of the view across await points.
2293    /// The returned future will be polled on the main thread.
2294    pub fn spawn<Fut, R>(
2295        &mut self,
2296        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2297    ) -> Task<R>
2298    where
2299        R: 'static,
2300        Fut: Future<Output = R> + 'static,
2301    {
2302        let view = self.view().downgrade();
2303        self.window_cx.spawn(|cx| f(view, cx))
2304    }
2305
2306    /// Updates the global state of the given type.
2307    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2308    where
2309        G: Global,
2310    {
2311        let mut global = self.app.lease_global::<G>();
2312        let result = f(&mut global, self);
2313        self.app.end_global_lease(global);
2314        result
2315    }
2316
2317    /// Register a callback to be invoked when the given global state changes.
2318    pub fn observe_global<G: Global>(
2319        &mut self,
2320        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2321    ) -> Subscription {
2322        let window_handle = self.window.handle;
2323        let view = self.view().downgrade();
2324        let (subscription, activate) = self.global_observers.insert(
2325            TypeId::of::<G>(),
2326            Box::new(move |cx| {
2327                window_handle
2328                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2329                    .unwrap_or(false)
2330            }),
2331        );
2332        self.app.defer(move |_| activate());
2333        subscription
2334    }
2335
2336    /// Register a callback to be invoked when the given Action type is dispatched to the window.
2337    pub fn on_action(
2338        &mut self,
2339        action_type: TypeId,
2340        listener: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2341    ) {
2342        let handle = self.view().clone();
2343        self.window_cx
2344            .on_action(action_type, move |action, phase, cx| {
2345                handle.update(cx, |view, cx| {
2346                    listener(view, action, phase, cx);
2347                })
2348            });
2349    }
2350
2351    /// Emit an event to be handled any other views that have subscribed via [ViewContext::subscribe].
2352    pub fn emit<Evt>(&mut self, event: Evt)
2353    where
2354        Evt: 'static,
2355        V: EventEmitter<Evt>,
2356    {
2357        let emitter = self.view.model.entity_id;
2358        self.app.push_effect(Effect::Emit {
2359            emitter,
2360            event_type: TypeId::of::<Evt>(),
2361            event: Box::new(event),
2362        });
2363    }
2364
2365    /// Move focus to the current view, assuming it implements [`FocusableView`].
2366    pub fn focus_self(&mut self)
2367    where
2368        V: FocusableView,
2369    {
2370        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2371    }
2372
2373    /// Convenience method for accessing view state in an event callback.
2374    ///
2375    /// Many GPUI callbacks take the form of `Fn(&E, &mut WindowContext)`,
2376    /// but it's often useful to be able to access view state in these
2377    /// callbacks. This method provides a convenient way to do so.
2378    pub fn listener<E>(
2379        &self,
2380        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2381    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2382        let view = self.view().downgrade();
2383        move |e: &E, cx: &mut WindowContext| {
2384            view.update(cx, |view, cx| f(view, e, cx)).ok();
2385        }
2386    }
2387}
2388
2389impl<V> Context for ViewContext<'_, V> {
2390    type Result<U> = U;
2391
2392    fn new_model<T: 'static>(
2393        &mut self,
2394        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2395    ) -> Model<T> {
2396        self.window_cx.new_model(build_model)
2397    }
2398
2399    fn update_model<T: 'static, R>(
2400        &mut self,
2401        model: &Model<T>,
2402        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2403    ) -> R {
2404        self.window_cx.update_model(model, update)
2405    }
2406
2407    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2408    where
2409        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2410    {
2411        self.window_cx.update_window(window, update)
2412    }
2413
2414    fn read_model<T, R>(
2415        &self,
2416        handle: &Model<T>,
2417        read: impl FnOnce(&T, &AppContext) -> R,
2418    ) -> Self::Result<R>
2419    where
2420        T: 'static,
2421    {
2422        self.window_cx.read_model(handle, read)
2423    }
2424
2425    fn read_window<T, R>(
2426        &self,
2427        window: &WindowHandle<T>,
2428        read: impl FnOnce(View<T>, &AppContext) -> R,
2429    ) -> Result<R>
2430    where
2431        T: 'static,
2432    {
2433        self.window_cx.read_window(window, read)
2434    }
2435}
2436
2437impl<V: 'static> VisualContext for ViewContext<'_, V> {
2438    fn new_view<W: Render + 'static>(
2439        &mut self,
2440        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2441    ) -> Self::Result<View<W>> {
2442        self.window_cx.new_view(build_view_state)
2443    }
2444
2445    fn update_view<V2: 'static, R>(
2446        &mut self,
2447        view: &View<V2>,
2448        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2449    ) -> Self::Result<R> {
2450        self.window_cx.update_view(view, update)
2451    }
2452
2453    fn replace_root_view<W>(
2454        &mut self,
2455        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2456    ) -> Self::Result<View<W>>
2457    where
2458        W: 'static + Render,
2459    {
2460        self.window_cx.replace_root_view(build_view)
2461    }
2462
2463    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2464        self.window_cx.focus_view(view)
2465    }
2466
2467    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2468        self.window_cx.dismiss_view(view)
2469    }
2470}
2471
2472impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2473    type Target = WindowContext<'a>;
2474
2475    fn deref(&self) -> &Self::Target {
2476        &self.window_cx
2477    }
2478}
2479
2480impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2481    fn deref_mut(&mut self) -> &mut Self::Target {
2482        &mut self.window_cx
2483    }
2484}
2485
2486// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2487slotmap::new_key_type! {
2488    /// A unique identifier for a window.
2489    pub struct WindowId;
2490}
2491
2492impl WindowId {
2493    /// Converts this window ID to a `u64`.
2494    pub fn as_u64(&self) -> u64 {
2495        self.0.as_ffi()
2496    }
2497}
2498
2499/// A handle to a window with a specific root view type.
2500/// Note that this does not keep the window alive on its own.
2501#[derive(Deref, DerefMut)]
2502pub struct WindowHandle<V> {
2503    #[deref]
2504    #[deref_mut]
2505    pub(crate) any_handle: AnyWindowHandle,
2506    state_type: PhantomData<V>,
2507}
2508
2509impl<V: 'static + Render> WindowHandle<V> {
2510    /// Creates a new handle from a window ID.
2511    /// This does not check if the root type of the window is `V`.
2512    pub fn new(id: WindowId) -> Self {
2513        WindowHandle {
2514            any_handle: AnyWindowHandle {
2515                id,
2516                state_type: TypeId::of::<V>(),
2517            },
2518            state_type: PhantomData,
2519        }
2520    }
2521
2522    /// Get the root view out of this window.
2523    ///
2524    /// This will fail if the window is closed or if the root view's type does not match `V`.
2525    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2526    where
2527        C: Context,
2528    {
2529        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2530            root_view
2531                .downcast::<V>()
2532                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2533        }))
2534    }
2535
2536    /// Updates the root view of this window.
2537    ///
2538    /// This will fail if the window has been closed or if the root view's type does not match
2539    pub fn update<C, R>(
2540        &self,
2541        cx: &mut C,
2542        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2543    ) -> Result<R>
2544    where
2545        C: Context,
2546    {
2547        cx.update_window(self.any_handle, |root_view, cx| {
2548            let view = root_view
2549                .downcast::<V>()
2550                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2551            Ok(cx.update_view(&view, update))
2552        })?
2553    }
2554
2555    /// Read the root view out of this window.
2556    ///
2557    /// This will fail if the window is closed or if the root view's type does not match `V`.
2558    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2559        let x = cx
2560            .windows
2561            .get(self.id)
2562            .and_then(|window| {
2563                window
2564                    .as_ref()
2565                    .and_then(|window| window.root_view.clone())
2566                    .map(|root_view| root_view.downcast::<V>())
2567            })
2568            .ok_or_else(|| anyhow!("window not found"))?
2569            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2570
2571        Ok(x.read(cx))
2572    }
2573
2574    /// Read the root view out of this window, with a callback
2575    ///
2576    /// This will fail if the window is closed or if the root view's type does not match `V`.
2577    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2578    where
2579        C: Context,
2580    {
2581        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2582    }
2583
2584    /// Read the root view pointer off of this window.
2585    ///
2586    /// This will fail if the window is closed or if the root view's type does not match `V`.
2587    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2588    where
2589        C: Context,
2590    {
2591        cx.read_window(self, |root_view, _cx| root_view.clone())
2592    }
2593
2594    /// Check if this window is 'active'.
2595    ///
2596    /// Will return `None` if the window is closed or currently
2597    /// borrowed.
2598    pub fn is_active(&self, cx: &mut AppContext) -> Option<bool> {
2599        cx.update_window(self.any_handle, |_, cx| cx.is_window_active())
2600            .ok()
2601    }
2602}
2603
2604impl<V> Copy for WindowHandle<V> {}
2605
2606impl<V> Clone for WindowHandle<V> {
2607    fn clone(&self) -> Self {
2608        *self
2609    }
2610}
2611
2612impl<V> PartialEq for WindowHandle<V> {
2613    fn eq(&self, other: &Self) -> bool {
2614        self.any_handle == other.any_handle
2615    }
2616}
2617
2618impl<V> Eq for WindowHandle<V> {}
2619
2620impl<V> Hash for WindowHandle<V> {
2621    fn hash<H: Hasher>(&self, state: &mut H) {
2622        self.any_handle.hash(state);
2623    }
2624}
2625
2626impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle {
2627    fn from(val: WindowHandle<V>) -> Self {
2628        val.any_handle
2629    }
2630}
2631
2632/// A handle to a window with any root view type, which can be downcast to a window with a specific root view type.
2633#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2634pub struct AnyWindowHandle {
2635    pub(crate) id: WindowId,
2636    state_type: TypeId,
2637}
2638
2639impl AnyWindowHandle {
2640    /// Get the ID of this window.
2641    pub fn window_id(&self) -> WindowId {
2642        self.id
2643    }
2644
2645    /// Attempt to convert this handle to a window handle with a specific root view type.
2646    /// If the types do not match, this will return `None`.
2647    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2648        if TypeId::of::<T>() == self.state_type {
2649            Some(WindowHandle {
2650                any_handle: *self,
2651                state_type: PhantomData,
2652            })
2653        } else {
2654            None
2655        }
2656    }
2657
2658    /// Updates the state of the root view of this window.
2659    ///
2660    /// This will fail if the window has been closed.
2661    pub fn update<C, R>(
2662        self,
2663        cx: &mut C,
2664        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2665    ) -> Result<R>
2666    where
2667        C: Context,
2668    {
2669        cx.update_window(self, update)
2670    }
2671
2672    /// Read the state of the root view of this window.
2673    ///
2674    /// This will fail if the window has been closed.
2675    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2676    where
2677        C: Context,
2678        T: 'static,
2679    {
2680        let view = self
2681            .downcast::<T>()
2682            .context("the type of the window's root view has changed")?;
2683
2684        cx.read_window(&view, read)
2685    }
2686}
2687
2688/// An identifier for an [`Element`](crate::Element).
2689///
2690/// Can be constructed with a string, a number, or both, as well
2691/// as other internal representations.
2692#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2693pub enum ElementId {
2694    /// The ID of a View element
2695    View(EntityId),
2696    /// An integer ID.
2697    Integer(usize),
2698    /// A string based ID.
2699    Name(SharedString),
2700    /// An ID that's equated with a focus handle.
2701    FocusHandle(FocusId),
2702    /// A combination of a name and an integer.
2703    NamedInteger(SharedString, usize),
2704}
2705
2706impl Display for ElementId {
2707    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
2708        match self {
2709            ElementId::View(entity_id) => write!(f, "view-{}", entity_id)?,
2710            ElementId::Integer(ix) => write!(f, "{}", ix)?,
2711            ElementId::Name(name) => write!(f, "{}", name)?,
2712            ElementId::FocusHandle(_) => write!(f, "FocusHandle")?,
2713            ElementId::NamedInteger(s, i) => write!(f, "{}-{}", s, i)?,
2714        }
2715
2716        Ok(())
2717    }
2718}
2719
2720impl TryInto<SharedString> for ElementId {
2721    type Error = anyhow::Error;
2722
2723    fn try_into(self) -> anyhow::Result<SharedString> {
2724        if let ElementId::Name(name) = self {
2725            Ok(name)
2726        } else {
2727            Err(anyhow!("element id is not string"))
2728        }
2729    }
2730}
2731
2732impl From<usize> for ElementId {
2733    fn from(id: usize) -> Self {
2734        ElementId::Integer(id)
2735    }
2736}
2737
2738impl From<i32> for ElementId {
2739    fn from(id: i32) -> Self {
2740        Self::Integer(id as usize)
2741    }
2742}
2743
2744impl From<SharedString> for ElementId {
2745    fn from(name: SharedString) -> Self {
2746        ElementId::Name(name)
2747    }
2748}
2749
2750impl From<&'static str> for ElementId {
2751    fn from(name: &'static str) -> Self {
2752        ElementId::Name(name.into())
2753    }
2754}
2755
2756impl<'a> From<&'a FocusHandle> for ElementId {
2757    fn from(handle: &'a FocusHandle) -> Self {
2758        ElementId::FocusHandle(handle.id)
2759    }
2760}
2761
2762impl From<(&'static str, EntityId)> for ElementId {
2763    fn from((name, id): (&'static str, EntityId)) -> Self {
2764        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2765    }
2766}
2767
2768impl From<(&'static str, usize)> for ElementId {
2769    fn from((name, id): (&'static str, usize)) -> Self {
2770        ElementId::NamedInteger(name.into(), id)
2771    }
2772}
2773
2774impl From<(&'static str, u64)> for ElementId {
2775    fn from((name, id): (&'static str, u64)) -> Self {
2776        ElementId::NamedInteger(name.into(), id as usize)
2777    }
2778}
2779
2780/// A rectangle to be rendered in the window at the given position and size.
2781/// Passed as an argument [`ElementContext::paint_quad`].
2782#[derive(Clone)]
2783pub struct PaintQuad {
2784    bounds: Bounds<Pixels>,
2785    corner_radii: Corners<Pixels>,
2786    background: Hsla,
2787    border_widths: Edges<Pixels>,
2788    border_color: Hsla,
2789}
2790
2791impl PaintQuad {
2792    /// Sets the corner radii of the quad.
2793    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
2794        PaintQuad {
2795            corner_radii: corner_radii.into(),
2796            ..self
2797        }
2798    }
2799
2800    /// Sets the border widths of the quad.
2801    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
2802        PaintQuad {
2803            border_widths: border_widths.into(),
2804            ..self
2805        }
2806    }
2807
2808    /// Sets the border color of the quad.
2809    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
2810        PaintQuad {
2811            border_color: border_color.into(),
2812            ..self
2813        }
2814    }
2815
2816    /// Sets the background color of the quad.
2817    pub fn background(self, background: impl Into<Hsla>) -> Self {
2818        PaintQuad {
2819            background: background.into(),
2820            ..self
2821        }
2822    }
2823}
2824
2825/// Creates a quad with the given parameters.
2826pub fn quad(
2827    bounds: Bounds<Pixels>,
2828    corner_radii: impl Into<Corners<Pixels>>,
2829    background: impl Into<Hsla>,
2830    border_widths: impl Into<Edges<Pixels>>,
2831    border_color: impl Into<Hsla>,
2832) -> PaintQuad {
2833    PaintQuad {
2834        bounds,
2835        corner_radii: corner_radii.into(),
2836        background: background.into(),
2837        border_widths: border_widths.into(),
2838        border_color: border_color.into(),
2839    }
2840}
2841
2842/// Creates a filled quad with the given bounds and background color.
2843pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
2844    PaintQuad {
2845        bounds: bounds.into(),
2846        corner_radii: (0.).into(),
2847        background: background.into(),
2848        border_widths: (0.).into(),
2849        border_color: transparent_black(),
2850    }
2851}
2852
2853/// Creates a rectangle outline with the given bounds, border color, and a 1px border width
2854pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
2855    PaintQuad {
2856        bounds: bounds.into(),
2857        corner_radii: (0.).into(),
2858        background: transparent_black(),
2859        border_widths: (1.).into(),
2860        border_color: border_color.into(),
2861    }
2862}