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