window.rs

   1use crate::{
   2    px, size, transparent_black, Action, AnyDrag, AnyView, AppContext, Arena, AsyncWindowContext,
   3    AvailableSpace, Bounds, Context, Corners, CursorStyle, DispatchActionListener, DispatchNodeId,
   4    DispatchTree, DisplayId, Edges, Effect, Entity, EntityId, EventEmitter, FileDropEvent, Flatten,
   5    Global, GlobalElementId, Hsla, KeyBinding, KeyContext, KeyDownEvent, KeyMatch, KeymatchResult,
   6    Keystroke, KeystrokeEvent, Model, ModelContext, Modifiers, MouseButton, MouseMoveEvent,
   7    MouseUpEvent, Pixels, PlatformAtlas, PlatformDisplay, PlatformInput, PlatformWindow, Point,
   8    PromptLevel, Render, ScaledPixels, SharedString, Size, SubscriberSet, Subscription,
   9    TaffyLayoutEngine, Task, View, VisualContext, WeakView, WindowAppearance, WindowBounds,
  10    WindowOptions, 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 slotmap::SlotMap;
  18use smallvec::SmallVec;
  19use std::{
  20    any::{Any, TypeId},
  21    borrow::{Borrow, BorrowMut},
  22    cell::{Cell, RefCell},
  23    fmt::{Debug, Display},
  24    future::Future,
  25    hash::{Hash, Hasher},
  26    marker::PhantomData,
  27    mem,
  28    rc::Rc,
  29    sync::{
  30        atomic::{AtomicUsize, Ordering::SeqCst},
  31        Arc,
  32    },
  33    time::{Duration, Instant},
  34};
  35use util::{measure, ResultExt};
  36
  37mod element_cx;
  38pub use element_cx::*;
  39
  40const ACTIVE_DRAG_Z_INDEX: u16 = 1;
  41
  42/// A global stacking order, which is created by stacking successive z-index values.
  43/// Each z-index will always be interpreted in the context of its parent z-index.
  44#[derive(Debug, Deref, DerefMut, Clone, Ord, PartialOrd, PartialEq, Eq, Default)]
  45pub struct StackingOrder(SmallVec<[StackingContext; 64]>);
  46
  47/// A single entry in a primitive's z-index stacking order
  48#[derive(Clone, Ord, PartialOrd, PartialEq, Eq, Default)]
  49pub struct StackingContext {
  50    pub(crate) z_index: u16,
  51    pub(crate) id: u16,
  52}
  53
  54impl std::fmt::Debug for StackingContext {
  55    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  56        write!(f, "{{{}.{}}} ", self.z_index, self.id)
  57    }
  58}
  59
  60/// Represents the two different phases when dispatching events.
  61#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  62pub enum DispatchPhase {
  63    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  64    /// invoked front to back and keyboard event listeners are invoked from the focused element
  65    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  66    /// registering event listeners.
  67    #[default]
  68    Bubble,
  69    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  70    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  71    /// is used for special purposes such as clearing the "pressed" state for click events. If
  72    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  73    /// outside of the immediate region may rely on detecting non-local events during this phase.
  74    Capture,
  75}
  76
  77impl DispatchPhase {
  78    /// Returns true if this represents the "bubble" phase.
  79    pub fn bubble(self) -> bool {
  80        self == DispatchPhase::Bubble
  81    }
  82
  83    /// Returns true if this represents the "capture" phase.
  84    pub fn capture(self) -> bool {
  85        self == DispatchPhase::Capture
  86    }
  87}
  88
  89type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
  90
  91type AnyWindowFocusListener = Box<dyn FnMut(&FocusEvent, &mut WindowContext) -> bool + 'static>;
  92
  93struct FocusEvent {
  94    previous_focus_path: SmallVec<[FocusId; 8]>,
  95    current_focus_path: SmallVec<[FocusId; 8]>,
  96}
  97
  98slotmap::new_key_type! {
  99    /// A globally unique identifier for a focusable element.
 100    pub struct FocusId;
 101}
 102
 103thread_local! {
 104    pub(crate) static ELEMENT_ARENA: RefCell<Arena> = RefCell::new(Arena::new(8 * 1024 * 1024));
 105}
 106
 107impl FocusId {
 108    /// Obtains whether the element associated with this handle is currently focused.
 109    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 110        cx.window.focus == Some(*self)
 111    }
 112
 113    /// Obtains whether the element associated with this handle contains the focused
 114    /// element or is itself focused.
 115    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 116        cx.focused()
 117            .map_or(false, |focused| self.contains(focused.id, cx))
 118    }
 119
 120    /// Obtains whether the element associated with this handle is contained within the
 121    /// focused element or is itself focused.
 122    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 123        let focused = cx.focused();
 124        focused.map_or(false, |focused| focused.id.contains(*self, cx))
 125    }
 126
 127    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 128    pub(crate) fn contains(&self, other: Self, cx: &WindowContext) -> bool {
 129        cx.window
 130            .rendered_frame
 131            .dispatch_tree
 132            .focus_contains(*self, other)
 133    }
 134}
 135
 136/// A handle which can be used to track and manipulate the focused element in a window.
 137pub struct FocusHandle {
 138    pub(crate) id: FocusId,
 139    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 140}
 141
 142impl std::fmt::Debug for FocusHandle {
 143    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 144        f.write_fmt(format_args!("FocusHandle({:?})", self.id))
 145    }
 146}
 147
 148impl FocusHandle {
 149    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
 150        let id = handles.write().insert(AtomicUsize::new(1));
 151        Self {
 152            id,
 153            handles: handles.clone(),
 154        }
 155    }
 156
 157    pub(crate) fn for_id(
 158        id: FocusId,
 159        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 160    ) -> Option<Self> {
 161        let lock = handles.read();
 162        let ref_count = lock.get(id)?;
 163        if ref_count.load(SeqCst) == 0 {
 164            None
 165        } else {
 166            ref_count.fetch_add(1, SeqCst);
 167            Some(Self {
 168                id,
 169                handles: handles.clone(),
 170            })
 171        }
 172    }
 173
 174    /// Moves the focus to the element associated with this handle.
 175    pub fn focus(&self, cx: &mut WindowContext) {
 176        cx.focus(self)
 177    }
 178
 179    /// Obtains whether the element associated with this handle is currently focused.
 180    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 181        self.id.is_focused(cx)
 182    }
 183
 184    /// Obtains whether the element associated with this handle contains the focused
 185    /// element or is itself focused.
 186    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 187        self.id.contains_focused(cx)
 188    }
 189
 190    /// Obtains whether the element associated with this handle is contained within the
 191    /// focused element or is itself focused.
 192    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 193        self.id.within_focused(cx)
 194    }
 195
 196    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 197    pub fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 198        self.id.contains(other.id, cx)
 199    }
 200}
 201
 202impl Clone for FocusHandle {
 203    fn clone(&self) -> Self {
 204        Self::for_id(self.id, &self.handles).unwrap()
 205    }
 206}
 207
 208impl PartialEq for FocusHandle {
 209    fn eq(&self, other: &Self) -> bool {
 210        self.id == other.id
 211    }
 212}
 213
 214impl Eq for FocusHandle {}
 215
 216impl Drop for FocusHandle {
 217    fn drop(&mut self) {
 218        self.handles
 219            .read()
 220            .get(self.id)
 221            .unwrap()
 222            .fetch_sub(1, SeqCst);
 223    }
 224}
 225
 226/// FocusableView allows users of your view to easily
 227/// focus it (using cx.focus_view(view))
 228pub trait FocusableView: 'static + Render {
 229    /// Returns the focus handle associated with this view.
 230    fn focus_handle(&self, cx: &AppContext) -> FocusHandle;
 231}
 232
 233/// ManagedView is a view (like a Modal, Popover, Menu, etc.)
 234/// where the lifecycle of the view is handled by another view.
 235pub trait ManagedView: FocusableView + EventEmitter<DismissEvent> {}
 236
 237impl<M: FocusableView + EventEmitter<DismissEvent>> ManagedView for M {}
 238
 239/// Emitted by implementers of [`ManagedView`] to indicate the view should be dismissed, such as when a view is presented as a modal.
 240pub struct DismissEvent;
 241
 242type FrameCallback = Box<dyn FnOnce(&mut WindowContext)>;
 243
 244// Holds the state for a specific window.
 245#[doc(hidden)]
 246pub struct Window {
 247    pub(crate) handle: AnyWindowHandle,
 248    pub(crate) removed: bool,
 249    pub(crate) platform_window: Box<dyn PlatformWindow>,
 250    display_id: DisplayId,
 251    sprite_atlas: Arc<dyn PlatformAtlas>,
 252    text_system: Arc<WindowTextSystem>,
 253    pub(crate) rem_size: Pixels,
 254    pub(crate) viewport_size: Size<Pixels>,
 255    layout_engine: Option<TaffyLayoutEngine>,
 256    pub(crate) root_view: Option<AnyView>,
 257    pub(crate) element_id_stack: GlobalElementId,
 258    pub(crate) rendered_frame: Frame,
 259    pub(crate) next_frame: Frame,
 260    next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>>,
 261    pub(crate) dirty_views: FxHashSet<EntityId>,
 262    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 263    focus_listeners: SubscriberSet<(), AnyWindowFocusListener>,
 264    focus_lost_listeners: SubscriberSet<(), AnyObserver>,
 265    default_prevented: bool,
 266    mouse_position: Point<Pixels>,
 267    modifiers: Modifiers,
 268    scale_factor: f32,
 269    bounds: WindowBounds,
 270    bounds_observers: SubscriberSet<(), AnyObserver>,
 271    appearance: WindowAppearance,
 272    appearance_observers: SubscriberSet<(), AnyObserver>,
 273    active: Rc<Cell<bool>>,
 274    pub(crate) dirty: Rc<Cell<bool>>,
 275    pub(crate) needs_present: Rc<Cell<bool>>,
 276    pub(crate) last_input_timestamp: Rc<Cell<Instant>>,
 277    pub(crate) refreshing: bool,
 278    pub(crate) drawing: bool,
 279    activation_observers: SubscriberSet<(), AnyObserver>,
 280    pub(crate) focus: Option<FocusId>,
 281    focus_enabled: bool,
 282    pending_input: Option<PendingInput>,
 283}
 284
 285#[derive(Default, Debug)]
 286struct PendingInput {
 287    keystrokes: SmallVec<[Keystroke; 1]>,
 288    bindings: SmallVec<[KeyBinding; 1]>,
 289    focus: Option<FocusId>,
 290    timer: Option<Task<()>>,
 291}
 292
 293impl PendingInput {
 294    fn input(&self) -> String {
 295        self.keystrokes
 296            .iter()
 297            .flat_map(|k| k.ime_key.clone())
 298            .collect::<Vec<String>>()
 299            .join("")
 300    }
 301
 302    fn used_by_binding(&self, binding: &KeyBinding) -> bool {
 303        if self.keystrokes.is_empty() {
 304            return true;
 305        }
 306        let keystroke = &self.keystrokes[0];
 307        for candidate in keystroke.match_candidates() {
 308            if binding.match_keystrokes(&[candidate]) == KeyMatch::Pending {
 309                return true;
 310            }
 311        }
 312        false
 313    }
 314}
 315
 316pub(crate) struct ElementStateBox {
 317    pub(crate) inner: Box<dyn Any>,
 318    pub(crate) parent_view_id: EntityId,
 319    #[cfg(debug_assertions)]
 320    pub(crate) type_name: &'static str,
 321}
 322
 323impl Window {
 324    pub(crate) fn new(
 325        handle: AnyWindowHandle,
 326        options: WindowOptions,
 327        cx: &mut AppContext,
 328    ) -> Self {
 329        let platform_window = cx.platform.open_window(handle, options);
 330        let display_id = platform_window.display().id();
 331        let sprite_atlas = platform_window.sprite_atlas();
 332        let mouse_position = platform_window.mouse_position();
 333        let modifiers = platform_window.modifiers();
 334        let content_size = platform_window.content_size();
 335        let scale_factor = platform_window.scale_factor();
 336        let bounds = platform_window.bounds();
 337        let appearance = platform_window.appearance();
 338        let text_system = Arc::new(WindowTextSystem::new(cx.text_system().clone()));
 339        let dirty = Rc::new(Cell::new(true));
 340        let active = Rc::new(Cell::new(false));
 341        let needs_present = Rc::new(Cell::new(false));
 342        let next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>> = Default::default();
 343        let last_input_timestamp = Rc::new(Cell::new(Instant::now()));
 344
 345        platform_window.on_close(Box::new({
 346            let mut cx = cx.to_async();
 347            move || {
 348                let _ = handle.update(&mut cx, |_, cx| cx.remove_window());
 349            }
 350        }));
 351        platform_window.on_request_frame(Box::new({
 352            let mut cx = cx.to_async();
 353            let dirty = dirty.clone();
 354            let active = active.clone();
 355            let needs_present = needs_present.clone();
 356            let next_frame_callbacks = next_frame_callbacks.clone();
 357            let last_input_timestamp = last_input_timestamp.clone();
 358            move || {
 359                let next_frame_callbacks = next_frame_callbacks.take();
 360                if !next_frame_callbacks.is_empty() {
 361                    handle
 362                        .update(&mut cx, |_, cx| {
 363                            for callback in next_frame_callbacks {
 364                                callback(cx);
 365                            }
 366                        })
 367                        .log_err();
 368                }
 369
 370                // Keep presenting the current scene for 1 extra second since the
 371                // last input to prevent the display from underclocking the refresh rate.
 372                let needs_present = needs_present.get()
 373                    || (active.get()
 374                        && last_input_timestamp.get().elapsed() < Duration::from_secs(1));
 375
 376                if dirty.get() {
 377                    measure("frame duration", || {
 378                        handle
 379                            .update(&mut cx, |_, cx| {
 380                                cx.draw();
 381                                cx.present();
 382                            })
 383                            .log_err();
 384                    })
 385                } else if needs_present {
 386                    handle.update(&mut cx, |_, cx| cx.present()).log_err();
 387                }
 388            }
 389        }));
 390        platform_window.on_resize(Box::new({
 391            let mut cx = cx.to_async();
 392            move |_, _| {
 393                handle
 394                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 395                    .log_err();
 396            }
 397        }));
 398        platform_window.on_moved(Box::new({
 399            let mut cx = cx.to_async();
 400            move || {
 401                handle
 402                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 403                    .log_err();
 404            }
 405        }));
 406        platform_window.on_appearance_changed(Box::new({
 407            let mut cx = cx.to_async();
 408            move || {
 409                handle
 410                    .update(&mut cx, |_, cx| cx.appearance_changed())
 411                    .log_err();
 412            }
 413        }));
 414        platform_window.on_active_status_change(Box::new({
 415            let mut cx = cx.to_async();
 416            move |active| {
 417                handle
 418                    .update(&mut cx, |_, cx| {
 419                        cx.window.active.set(active);
 420                        cx.window
 421                            .activation_observers
 422                            .clone()
 423                            .retain(&(), |callback| callback(cx));
 424                    })
 425                    .log_err();
 426            }
 427        }));
 428
 429        platform_window.on_input({
 430            let mut cx = cx.to_async();
 431            Box::new(move |event| {
 432                handle
 433                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 434                    .log_err()
 435                    .unwrap_or(false)
 436            })
 437        });
 438
 439        Window {
 440            handle,
 441            removed: false,
 442            platform_window,
 443            display_id,
 444            sprite_atlas,
 445            text_system,
 446            rem_size: px(16.),
 447            viewport_size: content_size,
 448            layout_engine: Some(TaffyLayoutEngine::new()),
 449            root_view: None,
 450            element_id_stack: GlobalElementId::default(),
 451            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 452            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 453            next_frame_callbacks,
 454            dirty_views: FxHashSet::default(),
 455            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 456            focus_listeners: SubscriberSet::new(),
 457            focus_lost_listeners: SubscriberSet::new(),
 458            default_prevented: true,
 459            mouse_position,
 460            modifiers,
 461            scale_factor,
 462            bounds,
 463            bounds_observers: SubscriberSet::new(),
 464            appearance,
 465            appearance_observers: SubscriberSet::new(),
 466            active,
 467            dirty,
 468            needs_present,
 469            last_input_timestamp,
 470            refreshing: false,
 471            drawing: false,
 472            activation_observers: SubscriberSet::new(),
 473            focus: None,
 474            focus_enabled: true,
 475            pending_input: None,
 476        }
 477    }
 478    fn new_focus_listener(
 479        &mut self,
 480        value: AnyWindowFocusListener,
 481    ) -> (Subscription, impl FnOnce()) {
 482        self.focus_listeners.insert((), value)
 483    }
 484}
 485
 486/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 487/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 488/// to leave room to support more complex shapes in the future.
 489#[derive(Clone, Debug, Default, PartialEq, Eq)]
 490#[repr(C)]
 491pub struct ContentMask<P: Clone + Default + Debug> {
 492    /// The bounds
 493    pub bounds: Bounds<P>,
 494}
 495
 496impl ContentMask<Pixels> {
 497    /// Scale the content mask's pixel units by the given scaling factor.
 498    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 499        ContentMask {
 500            bounds: self.bounds.scale(factor),
 501        }
 502    }
 503
 504    /// Intersect the content mask with the given content mask.
 505    pub fn intersect(&self, other: &Self) -> Self {
 506        let bounds = self.bounds.intersect(&other.bounds);
 507        ContentMask { bounds }
 508    }
 509}
 510
 511/// Provides access to application state in the context of a single window. Derefs
 512/// to an [`AppContext`], so you can also pass a [`WindowContext`] to any method that takes
 513/// an [`AppContext`] and call any [`AppContext`] methods.
 514pub struct WindowContext<'a> {
 515    pub(crate) app: &'a mut AppContext,
 516    pub(crate) window: &'a mut Window,
 517}
 518
 519impl<'a> WindowContext<'a> {
 520    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 521        Self { app, window }
 522    }
 523
 524    /// Obtain a handle to the window that belongs to this context.
 525    pub fn window_handle(&self) -> AnyWindowHandle {
 526        self.window.handle
 527    }
 528
 529    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 530    pub fn refresh(&mut self) {
 531        if !self.window.drawing {
 532            self.window.refreshing = true;
 533            self.window.dirty.set(true);
 534        }
 535    }
 536
 537    /// Close this window.
 538    pub fn remove_window(&mut self) {
 539        self.window.removed = true;
 540    }
 541
 542    /// Obtain a new [`FocusHandle`], which allows you to track and manipulate the keyboard focus
 543    /// for elements rendered within this window.
 544    pub fn focus_handle(&mut self) -> FocusHandle {
 545        FocusHandle::new(&self.window.focus_handles)
 546    }
 547
 548    /// Obtain the currently focused [`FocusHandle`]. If no elements are focused, returns `None`.
 549    pub fn focused(&self) -> Option<FocusHandle> {
 550        self.window
 551            .focus
 552            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 553    }
 554
 555    /// Move focus to the element associated with the given [`FocusHandle`].
 556    pub fn focus(&mut self, handle: &FocusHandle) {
 557        if !self.window.focus_enabled || self.window.focus == Some(handle.id) {
 558            return;
 559        }
 560
 561        self.window.focus = Some(handle.id);
 562        self.window
 563            .rendered_frame
 564            .dispatch_tree
 565            .clear_pending_keystrokes();
 566        self.refresh();
 567    }
 568
 569    /// Remove focus from all elements within this context's window.
 570    pub fn blur(&mut self) {
 571        if !self.window.focus_enabled {
 572            return;
 573        }
 574
 575        self.window.focus = None;
 576        self.refresh();
 577    }
 578
 579    /// Blur the window and don't allow anything in it to be focused again.
 580    pub fn disable_focus(&mut self) {
 581        self.blur();
 582        self.window.focus_enabled = false;
 583    }
 584
 585    /// Accessor for the text system.
 586    pub fn text_system(&self) -> &Arc<WindowTextSystem> {
 587        &self.window.text_system
 588    }
 589
 590    /// Dispatch the given action on the currently focused element.
 591    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 592        let focus_handle = self.focused();
 593
 594        self.defer(move |cx| {
 595            let node_id = focus_handle
 596                .and_then(|handle| {
 597                    cx.window
 598                        .rendered_frame
 599                        .dispatch_tree
 600                        .focusable_node_id(handle.id)
 601                })
 602                .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 603
 604            cx.propagate_event = true;
 605            cx.dispatch_action_on_node(node_id, action);
 606        })
 607    }
 608
 609    pub(crate) fn dispatch_keystroke_observers(
 610        &mut self,
 611        event: &dyn Any,
 612        action: Option<Box<dyn Action>>,
 613    ) {
 614        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 615            return;
 616        };
 617
 618        self.keystroke_observers
 619            .clone()
 620            .retain(&(), move |callback| {
 621                (callback)(
 622                    &KeystrokeEvent {
 623                        keystroke: key_down_event.keystroke.clone(),
 624                        action: action.as_ref().map(|action| action.boxed_clone()),
 625                    },
 626                    self,
 627                );
 628                true
 629            });
 630    }
 631
 632    pub(crate) fn clear_pending_keystrokes(&mut self) {
 633        self.window
 634            .rendered_frame
 635            .dispatch_tree
 636            .clear_pending_keystrokes();
 637        self.window
 638            .next_frame
 639            .dispatch_tree
 640            .clear_pending_keystrokes();
 641    }
 642
 643    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 644    /// that are currently on the stack to be returned to the app.
 645    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 646        let handle = self.window.handle;
 647        self.app.defer(move |cx| {
 648            handle.update(cx, |_, cx| f(cx)).ok();
 649        });
 650    }
 651
 652    /// Subscribe to events emitted by a model or view.
 653    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
 654    /// 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.
 655    pub fn subscribe<Emitter, E, Evt>(
 656        &mut self,
 657        entity: &E,
 658        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 659    ) -> Subscription
 660    where
 661        Emitter: EventEmitter<Evt>,
 662        E: Entity<Emitter>,
 663        Evt: 'static,
 664    {
 665        let entity_id = entity.entity_id();
 666        let entity = entity.downgrade();
 667        let window_handle = self.window.handle;
 668        self.app.new_subscription(
 669            entity_id,
 670            (
 671                TypeId::of::<Evt>(),
 672                Box::new(move |event, cx| {
 673                    window_handle
 674                        .update(cx, |_, cx| {
 675                            if let Some(handle) = E::upgrade_from(&entity) {
 676                                let event = event.downcast_ref().expect("invalid event type");
 677                                on_event(handle, event, cx);
 678                                true
 679                            } else {
 680                                false
 681                            }
 682                        })
 683                        .unwrap_or(false)
 684                }),
 685            ),
 686        )
 687    }
 688
 689    /// Creates an [`AsyncWindowContext`], which has a static lifetime and can be held across
 690    /// await points in async code.
 691    pub fn to_async(&self) -> AsyncWindowContext {
 692        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 693    }
 694
 695    /// Schedule the given closure to be run directly after the current frame is rendered.
 696    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 697        RefCell::borrow_mut(&self.window.next_frame_callbacks).push(Box::new(callback));
 698    }
 699
 700    /// Spawn the future returned by the given closure on the application thread pool.
 701    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 702    /// use within your future.
 703    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 704    where
 705        R: 'static,
 706        Fut: Future<Output = R> + 'static,
 707    {
 708        self.app
 709            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 710    }
 711
 712    /// Updates the global of the given type. The given closure is given simultaneous mutable
 713    /// access both to the global and the context.
 714    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 715    where
 716        G: Global,
 717    {
 718        let mut global = self.app.lease_global::<G>();
 719        let result = f(&mut global, self);
 720        self.app.end_global_lease(global);
 721        result
 722    }
 723
 724    fn window_bounds_changed(&mut self) {
 725        self.window.scale_factor = self.window.platform_window.scale_factor();
 726        self.window.viewport_size = self.window.platform_window.content_size();
 727        self.window.bounds = self.window.platform_window.bounds();
 728        self.window.display_id = self.window.platform_window.display().id();
 729        self.refresh();
 730
 731        self.window
 732            .bounds_observers
 733            .clone()
 734            .retain(&(), |callback| callback(self));
 735    }
 736
 737    /// Returns the bounds of the current window in the global coordinate space, which could span across multiple displays.
 738    pub fn window_bounds(&self) -> WindowBounds {
 739        self.window.bounds
 740    }
 741
 742    fn appearance_changed(&mut self) {
 743        self.window.appearance = self.window.platform_window.appearance();
 744
 745        self.window
 746            .appearance_observers
 747            .clone()
 748            .retain(&(), |callback| callback(self));
 749    }
 750
 751    /// Returns the appearance of the current window.
 752    pub fn appearance(&self) -> WindowAppearance {
 753        self.window.appearance
 754    }
 755
 756    /// Returns the size of the drawable area within the window.
 757    pub fn viewport_size(&self) -> Size<Pixels> {
 758        self.window.viewport_size
 759    }
 760
 761    /// Returns whether this window is focused by the operating system (receiving key events).
 762    pub fn is_window_active(&self) -> bool {
 763        self.window.active.get()
 764    }
 765
 766    /// Toggle zoom on the window.
 767    pub fn zoom_window(&self) {
 768        self.window.platform_window.zoom();
 769    }
 770
 771    /// Updates the window's title at the platform level.
 772    pub fn set_window_title(&mut self, title: &str) {
 773        self.window.platform_window.set_title(title);
 774    }
 775
 776    /// Mark the window as dirty at the platform level.
 777    pub fn set_window_edited(&mut self, edited: bool) {
 778        self.window.platform_window.set_edited(edited);
 779    }
 780
 781    /// Determine the display on which the window is visible.
 782    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 783        self.platform
 784            .displays()
 785            .into_iter()
 786            .find(|display| display.id() == self.window.display_id)
 787    }
 788
 789    /// Show the platform character palette.
 790    pub fn show_character_palette(&self) {
 791        self.window.platform_window.show_character_palette();
 792    }
 793
 794    /// The scale factor of the display associated with the window. For example, it could
 795    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 796    /// be rendered as two pixels on screen.
 797    pub fn scale_factor(&self) -> f32 {
 798        self.window.scale_factor
 799    }
 800
 801    /// The size of an em for the base font of the application. Adjusting this value allows the
 802    /// UI to scale, just like zooming a web page.
 803    pub fn rem_size(&self) -> Pixels {
 804        self.window.rem_size
 805    }
 806
 807    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 808    /// UI to scale, just like zooming a web page.
 809    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 810        self.window.rem_size = rem_size.into();
 811    }
 812
 813    /// The line height associated with the current text style.
 814    pub fn line_height(&self) -> Pixels {
 815        let rem_size = self.rem_size();
 816        let text_style = self.text_style();
 817        text_style
 818            .line_height
 819            .to_pixels(text_style.font_size, rem_size)
 820    }
 821
 822    /// Call to prevent the default action of an event. Currently only used to prevent
 823    /// parent elements from becoming focused on mouse down.
 824    pub fn prevent_default(&mut self) {
 825        self.window.default_prevented = true;
 826    }
 827
 828    /// Obtain whether default has been prevented for the event currently being dispatched.
 829    pub fn default_prevented(&self) -> bool {
 830        self.window.default_prevented
 831    }
 832
 833    /// Determine whether the given action is available along the dispatch path to the currently focused element.
 834    pub fn is_action_available(&self, action: &dyn Action) -> bool {
 835        let target = self
 836            .focused()
 837            .and_then(|focused_handle| {
 838                self.window
 839                    .rendered_frame
 840                    .dispatch_tree
 841                    .focusable_node_id(focused_handle.id)
 842            })
 843            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
 844        self.window
 845            .rendered_frame
 846            .dispatch_tree
 847            .is_action_available(action, target)
 848    }
 849
 850    /// The position of the mouse relative to the window.
 851    pub fn mouse_position(&self) -> Point<Pixels> {
 852        self.window.mouse_position
 853    }
 854
 855    /// The current state of the keyboard's modifiers
 856    pub fn modifiers(&self) -> Modifiers {
 857        self.window.modifiers
 858    }
 859
 860    /// Returns true if there is no opaque layer containing the given point
 861    /// on top of the given level. Layers who are extensions of the queried layer
 862    /// are not considered to be on top of queried layer.
 863    pub fn was_top_layer(&self, point: &Point<Pixels>, layer: &StackingOrder) -> bool {
 864        // Precondition: the depth map is ordered from topmost to bottomost.
 865
 866        for (opaque_layer, _, bounds) in self.window.rendered_frame.depth_map.iter() {
 867            if layer >= opaque_layer {
 868                // The queried layer is either above or is the same as the this opaque layer.
 869                // Anything after this point is guaranteed to be below the queried layer.
 870                return true;
 871            }
 872
 873            if !bounds.contains(point) {
 874                // This opaque layer is above the queried layer but it doesn't contain
 875                // the given position, so we can ignore it even if it's above.
 876                continue;
 877            }
 878
 879            // At this point, we've established that this opaque layer is on top of the queried layer
 880            // and contains the position:
 881            // If neither the opaque layer or the queried layer is an extension of the other then
 882            // we know they are on different stacking orders, and return false.
 883            let is_on_same_layer = opaque_layer
 884                .iter()
 885                .zip(layer.iter())
 886                .all(|(a, b)| a.z_index == b.z_index);
 887
 888            if !is_on_same_layer {
 889                return false;
 890            }
 891        }
 892
 893        true
 894    }
 895
 896    pub(crate) fn was_top_layer_under_active_drag(
 897        &self,
 898        point: &Point<Pixels>,
 899        layer: &StackingOrder,
 900    ) -> bool {
 901        // Precondition: the depth map is ordered from topmost to bottomost.
 902
 903        for (opaque_layer, _, bounds) in self.window.rendered_frame.depth_map.iter() {
 904            if layer >= opaque_layer {
 905                // The queried layer is either above or is the same as the this opaque layer.
 906                // Anything after this point is guaranteed to be below the queried layer.
 907                return true;
 908            }
 909
 910            if !bounds.contains(point) {
 911                // This opaque layer is above the queried layer but it doesn't contain
 912                // the given position, so we can ignore it even if it's above.
 913                continue;
 914            }
 915
 916            // All normal content is rendered with a base z-index of 0, we know that if the root of this opaque layer
 917            // equals `ACTIVE_DRAG_Z_INDEX` then it must be the drag layer and we can ignore it as we are
 918            // looking to see if the queried layer was the topmost underneath the drag layer.
 919            if opaque_layer
 920                .first()
 921                .map(|c| c.z_index == ACTIVE_DRAG_Z_INDEX)
 922                .unwrap_or(false)
 923            {
 924                continue;
 925            }
 926
 927            // At this point, we've established that this opaque layer is on top of the queried layer
 928            // and contains the position:
 929            // If neither the opaque layer or the queried layer is an extension of the other then
 930            // we know they are on different stacking orders, and return false.
 931            let is_on_same_layer = opaque_layer
 932                .iter()
 933                .zip(layer.iter())
 934                .all(|(a, b)| a.z_index == b.z_index);
 935
 936            if !is_on_same_layer {
 937                return false;
 938            }
 939        }
 940
 941        true
 942    }
 943
 944    /// Called during painting to get the current stacking order.
 945    pub fn stacking_order(&self) -> &StackingOrder {
 946        &self.window.next_frame.z_index_stack
 947    }
 948
 949    /// Produces a new frame and assigns it to `rendered_frame`. To actually show
 950    /// the contents of the new [Scene], use [present].
 951    #[profiling::function]
 952    pub fn draw(&mut self) {
 953        self.window.dirty.set(false);
 954        self.window.drawing = true;
 955
 956        if let Some(requested_handler) = self.window.rendered_frame.requested_input_handler.as_mut()
 957        {
 958            let input_handler = self.window.platform_window.take_input_handler();
 959            requested_handler.handler = input_handler;
 960        }
 961
 962        let root_view = self.window.root_view.take().unwrap();
 963        self.with_element_context(|cx| {
 964            cx.with_z_index(0, |cx| {
 965                cx.with_key_dispatch(Some(KeyContext::default()), None, |_, cx| {
 966                    // We need to use cx.cx here so we can utilize borrow splitting
 967                    for (action_type, action_listeners) in &cx.cx.app.global_action_listeners {
 968                        for action_listener in action_listeners.iter().cloned() {
 969                            cx.cx.window.next_frame.dispatch_tree.on_action(
 970                                *action_type,
 971                                Rc::new(
 972                                    move |action: &dyn Any, phase, cx: &mut WindowContext<'_>| {
 973                                        action_listener(action, phase, cx)
 974                                    },
 975                                ),
 976                            )
 977                        }
 978                    }
 979
 980                    let available_space = cx.window.viewport_size.map(Into::into);
 981                    root_view.draw(Point::default(), available_space, cx);
 982                })
 983            })
 984        });
 985
 986        if let Some(active_drag) = self.app.active_drag.take() {
 987            self.with_element_context(|cx| {
 988                cx.with_z_index(ACTIVE_DRAG_Z_INDEX, |cx| {
 989                    let offset = cx.mouse_position() - active_drag.cursor_offset;
 990                    let available_space =
 991                        size(AvailableSpace::MinContent, AvailableSpace::MinContent);
 992                    active_drag.view.draw(offset, available_space, cx);
 993                })
 994            });
 995            self.active_drag = Some(active_drag);
 996        } else if let Some(tooltip_request) = self.window.next_frame.tooltip_request.take() {
 997            self.with_element_context(|cx| {
 998                cx.with_z_index(1, |cx| {
 999                    let available_space =
1000                        size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1001                    tooltip_request.tooltip.view.draw(
1002                        tooltip_request.tooltip.cursor_offset,
1003                        available_space,
1004                        cx,
1005                    );
1006                })
1007            });
1008            self.window.next_frame.tooltip_request = Some(tooltip_request);
1009        }
1010        self.window.dirty_views.clear();
1011
1012        self.window
1013            .next_frame
1014            .dispatch_tree
1015            .preserve_pending_keystrokes(
1016                &mut self.window.rendered_frame.dispatch_tree,
1017                self.window.focus,
1018            );
1019        self.window.next_frame.focus = self.window.focus;
1020        self.window.next_frame.window_active = self.window.active.get();
1021        self.window.root_view = Some(root_view);
1022
1023        // Set the cursor only if we're the active window.
1024        let cursor_style_request = self.window.next_frame.requested_cursor_style.take();
1025        if self.is_window_active() {
1026            let cursor_style =
1027                cursor_style_request.map_or(CursorStyle::Arrow, |request| request.style);
1028            self.platform.set_cursor_style(cursor_style);
1029        }
1030
1031        // Register requested input handler with the platform window.
1032        if let Some(requested_input) = self.window.next_frame.requested_input_handler.as_mut() {
1033            if let Some(handler) = requested_input.handler.take() {
1034                self.window.platform_window.set_input_handler(handler);
1035            }
1036        }
1037
1038        self.window.layout_engine.as_mut().unwrap().clear();
1039        self.text_system()
1040            .finish_frame(&self.window.next_frame.reused_views);
1041        self.window
1042            .next_frame
1043            .finish(&mut self.window.rendered_frame);
1044        ELEMENT_ARENA.with_borrow_mut(|element_arena| {
1045            let percentage = (element_arena.len() as f32 / element_arena.capacity() as f32) * 100.;
1046            if percentage >= 80. {
1047                log::warn!("elevated element arena occupation: {}.", percentage);
1048            }
1049            element_arena.clear();
1050        });
1051
1052        let previous_focus_path = self.window.rendered_frame.focus_path();
1053        let previous_window_active = self.window.rendered_frame.window_active;
1054        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1055        self.window.next_frame.clear();
1056        let current_focus_path = self.window.rendered_frame.focus_path();
1057        let current_window_active = self.window.rendered_frame.window_active;
1058
1059        if previous_focus_path != current_focus_path
1060            || previous_window_active != current_window_active
1061        {
1062            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1063                self.window
1064                    .focus_lost_listeners
1065                    .clone()
1066                    .retain(&(), |listener| listener(self));
1067            }
1068
1069            let event = FocusEvent {
1070                previous_focus_path: if previous_window_active {
1071                    previous_focus_path
1072                } else {
1073                    Default::default()
1074                },
1075                current_focus_path: if current_window_active {
1076                    current_focus_path
1077                } else {
1078                    Default::default()
1079                },
1080            };
1081            self.window
1082                .focus_listeners
1083                .clone()
1084                .retain(&(), |listener| listener(&event, self));
1085        }
1086        self.window.refreshing = false;
1087        self.window.drawing = false;
1088        self.window.needs_present.set(true);
1089    }
1090
1091    #[profiling::function]
1092    fn present(&self) {
1093        self.window
1094            .platform_window
1095            .draw(&self.window.rendered_frame.scene);
1096        self.window.needs_present.set(false);
1097        profiling::finish_frame!();
1098    }
1099
1100    /// Dispatch a given keystroke as though the user had typed it.
1101    /// You can create a keystroke with Keystroke::parse("").
1102    pub fn dispatch_keystroke(&mut self, keystroke: Keystroke) -> bool {
1103        let keystroke = keystroke.with_simulated_ime();
1104        if self.dispatch_event(PlatformInput::KeyDown(KeyDownEvent {
1105            keystroke: keystroke.clone(),
1106            is_held: false,
1107        })) {
1108            return true;
1109        }
1110
1111        if let Some(input) = keystroke.ime_key {
1112            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1113                input_handler.dispatch_input(&input, self);
1114                self.window.platform_window.set_input_handler(input_handler);
1115                return true;
1116            }
1117        }
1118
1119        false
1120    }
1121
1122    /// Represent this action as a key binding string, to display in the UI.
1123    pub fn keystroke_text_for(&self, action: &dyn Action) -> String {
1124        self.bindings_for_action(action)
1125            .into_iter()
1126            .next()
1127            .map(|binding| {
1128                binding
1129                    .keystrokes()
1130                    .iter()
1131                    .map(ToString::to_string)
1132                    .collect::<Vec<_>>()
1133                    .join(" ")
1134            })
1135            .unwrap_or_else(|| action.name().to_string())
1136    }
1137
1138    /// Dispatch a mouse or keyboard event on the window.
1139    #[profiling::function]
1140    pub fn dispatch_event(&mut self, event: PlatformInput) -> bool {
1141        self.window.last_input_timestamp.set(Instant::now());
1142        // Handlers may set this to false by calling `stop_propagation`.
1143        self.app.propagate_event = true;
1144        // Handlers may set this to true by calling `prevent_default`.
1145        self.window.default_prevented = false;
1146
1147        let event = match event {
1148            // Track the mouse position with our own state, since accessing the platform
1149            // API for the mouse position can only occur on the main thread.
1150            PlatformInput::MouseMove(mouse_move) => {
1151                self.window.mouse_position = mouse_move.position;
1152                self.window.modifiers = mouse_move.modifiers;
1153                PlatformInput::MouseMove(mouse_move)
1154            }
1155            PlatformInput::MouseDown(mouse_down) => {
1156                self.window.mouse_position = mouse_down.position;
1157                self.window.modifiers = mouse_down.modifiers;
1158                PlatformInput::MouseDown(mouse_down)
1159            }
1160            PlatformInput::MouseUp(mouse_up) => {
1161                self.window.mouse_position = mouse_up.position;
1162                self.window.modifiers = mouse_up.modifiers;
1163                PlatformInput::MouseUp(mouse_up)
1164            }
1165            PlatformInput::MouseExited(mouse_exited) => {
1166                self.window.modifiers = mouse_exited.modifiers;
1167                PlatformInput::MouseExited(mouse_exited)
1168            }
1169            PlatformInput::ModifiersChanged(modifiers_changed) => {
1170                self.window.modifiers = modifiers_changed.modifiers;
1171                PlatformInput::ModifiersChanged(modifiers_changed)
1172            }
1173            PlatformInput::ScrollWheel(scroll_wheel) => {
1174                self.window.mouse_position = scroll_wheel.position;
1175                self.window.modifiers = scroll_wheel.modifiers;
1176                PlatformInput::ScrollWheel(scroll_wheel)
1177            }
1178            // Translate dragging and dropping of external files from the operating system
1179            // to internal drag and drop events.
1180            PlatformInput::FileDrop(file_drop) => match file_drop {
1181                FileDropEvent::Entered { position, paths } => {
1182                    self.window.mouse_position = position;
1183                    if self.active_drag.is_none() {
1184                        self.active_drag = Some(AnyDrag {
1185                            value: Box::new(paths.clone()),
1186                            view: self.new_view(|_| paths).into(),
1187                            cursor_offset: position,
1188                        });
1189                    }
1190                    PlatformInput::MouseMove(MouseMoveEvent {
1191                        position,
1192                        pressed_button: Some(MouseButton::Left),
1193                        modifiers: Modifiers::default(),
1194                    })
1195                }
1196                FileDropEvent::Pending { position } => {
1197                    self.window.mouse_position = position;
1198                    PlatformInput::MouseMove(MouseMoveEvent {
1199                        position,
1200                        pressed_button: Some(MouseButton::Left),
1201                        modifiers: Modifiers::default(),
1202                    })
1203                }
1204                FileDropEvent::Submit { position } => {
1205                    self.activate(true);
1206                    self.window.mouse_position = position;
1207                    PlatformInput::MouseUp(MouseUpEvent {
1208                        button: MouseButton::Left,
1209                        position,
1210                        modifiers: Modifiers::default(),
1211                        click_count: 1,
1212                    })
1213                }
1214                FileDropEvent::Exited => PlatformInput::MouseUp(MouseUpEvent {
1215                    button: MouseButton::Left,
1216                    position: Point::default(),
1217                    modifiers: Modifiers::default(),
1218                    click_count: 1,
1219                }),
1220            },
1221            PlatformInput::KeyDown(_) | PlatformInput::KeyUp(_) => event,
1222        };
1223
1224        if let Some(any_mouse_event) = event.mouse_event() {
1225            self.dispatch_mouse_event(any_mouse_event);
1226        } else if let Some(any_key_event) = event.keyboard_event() {
1227            self.dispatch_key_event(any_key_event);
1228        }
1229
1230        !self.app.propagate_event
1231    }
1232
1233    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1234        if let Some(mut handlers) = self
1235            .window
1236            .rendered_frame
1237            .mouse_listeners
1238            .remove(&event.type_id())
1239        {
1240            // Because handlers may add other handlers, we sort every time.
1241            handlers.sort_by(|(a, _, _), (b, _, _)| a.cmp(b));
1242
1243            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1244            // special purposes, such as detecting events outside of a given Bounds.
1245            for (_, _, handler) in &mut handlers {
1246                self.with_element_context(|cx| {
1247                    handler(event, DispatchPhase::Capture, cx);
1248                });
1249                if !self.app.propagate_event {
1250                    break;
1251                }
1252            }
1253
1254            // Bubble phase, where most normal handlers do their work.
1255            if self.app.propagate_event {
1256                for (_, _, handler) in handlers.iter_mut().rev() {
1257                    self.with_element_context(|cx| {
1258                        handler(event, DispatchPhase::Bubble, cx);
1259                    });
1260                    if !self.app.propagate_event {
1261                        break;
1262                    }
1263                }
1264            }
1265
1266            self.window
1267                .rendered_frame
1268                .mouse_listeners
1269                .insert(event.type_id(), handlers);
1270        }
1271
1272        if self.app.propagate_event && self.has_active_drag() {
1273            if event.is::<MouseMoveEvent>() {
1274                // If this was a mouse move event, redraw the window so that the
1275                // active drag can follow the mouse cursor.
1276                self.refresh();
1277            } else if event.is::<MouseUpEvent>() {
1278                // If this was a mouse up event, cancel the active drag and redraw
1279                // the window.
1280                self.active_drag = None;
1281                self.refresh();
1282            }
1283        }
1284    }
1285
1286    fn dispatch_key_event(&mut self, event: &dyn Any) {
1287        if self.window.dirty.get() {
1288            self.draw();
1289        }
1290
1291        let node_id = self
1292            .window
1293            .focus
1294            .and_then(|focus_id| {
1295                self.window
1296                    .rendered_frame
1297                    .dispatch_tree
1298                    .focusable_node_id(focus_id)
1299            })
1300            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1301
1302        let dispatch_path = self
1303            .window
1304            .rendered_frame
1305            .dispatch_tree
1306            .dispatch_path(node_id);
1307
1308        if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1309            let KeymatchResult { bindings, pending } = self
1310                .window
1311                .rendered_frame
1312                .dispatch_tree
1313                .dispatch_key(&key_down_event.keystroke, &dispatch_path);
1314
1315            if pending {
1316                let mut currently_pending = self.window.pending_input.take().unwrap_or_default();
1317                if currently_pending.focus.is_some() && currently_pending.focus != self.window.focus
1318                {
1319                    currently_pending = PendingInput::default();
1320                }
1321                currently_pending.focus = self.window.focus;
1322                currently_pending
1323                    .keystrokes
1324                    .push(key_down_event.keystroke.clone());
1325                for binding in bindings {
1326                    currently_pending.bindings.push(binding);
1327                }
1328
1329                currently_pending.timer = Some(self.spawn(|mut cx| async move {
1330                    cx.background_executor.timer(Duration::from_secs(1)).await;
1331                    cx.update(move |cx| {
1332                        cx.clear_pending_keystrokes();
1333                        let Some(currently_pending) = cx.window.pending_input.take() else {
1334                            return;
1335                        };
1336                        cx.replay_pending_input(currently_pending)
1337                    })
1338                    .log_err();
1339                }));
1340                self.window.pending_input = Some(currently_pending);
1341
1342                self.propagate_event = false;
1343                return;
1344            } else if let Some(currently_pending) = self.window.pending_input.take() {
1345                if bindings
1346                    .iter()
1347                    .all(|binding| !currently_pending.used_by_binding(binding))
1348                {
1349                    self.replay_pending_input(currently_pending)
1350                }
1351            }
1352
1353            if !bindings.is_empty() {
1354                self.clear_pending_keystrokes();
1355            }
1356
1357            self.propagate_event = true;
1358            for binding in bindings {
1359                self.dispatch_action_on_node(node_id, binding.action.boxed_clone());
1360                if !self.propagate_event {
1361                    self.dispatch_keystroke_observers(event, Some(binding.action));
1362                    return;
1363                }
1364            }
1365        }
1366
1367        self.dispatch_key_down_up_event(event, &dispatch_path);
1368        if !self.propagate_event {
1369            return;
1370        }
1371
1372        self.dispatch_keystroke_observers(event, None);
1373    }
1374
1375    fn dispatch_key_down_up_event(
1376        &mut self,
1377        event: &dyn Any,
1378        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1379    ) {
1380        // Capture phase
1381        for node_id in dispatch_path {
1382            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1383
1384            for key_listener in node.key_listeners.clone() {
1385                self.with_element_context(|cx| {
1386                    key_listener(event, DispatchPhase::Capture, cx);
1387                });
1388                if !self.propagate_event {
1389                    return;
1390                }
1391            }
1392        }
1393
1394        // Bubble phase
1395        for node_id in dispatch_path.iter().rev() {
1396            // Handle low level key events
1397            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1398            for key_listener in node.key_listeners.clone() {
1399                self.with_element_context(|cx| {
1400                    key_listener(event, DispatchPhase::Bubble, cx);
1401                });
1402                if !self.propagate_event {
1403                    return;
1404                }
1405            }
1406        }
1407    }
1408
1409    /// Determine whether a potential multi-stroke key binding is in progress on this window.
1410    pub fn has_pending_keystrokes(&self) -> bool {
1411        self.window
1412            .rendered_frame
1413            .dispatch_tree
1414            .has_pending_keystrokes()
1415    }
1416
1417    fn replay_pending_input(&mut self, currently_pending: PendingInput) {
1418        let node_id = self
1419            .window
1420            .focus
1421            .and_then(|focus_id| {
1422                self.window
1423                    .rendered_frame
1424                    .dispatch_tree
1425                    .focusable_node_id(focus_id)
1426            })
1427            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1428
1429        if self.window.focus != currently_pending.focus {
1430            return;
1431        }
1432
1433        let input = currently_pending.input();
1434
1435        self.propagate_event = true;
1436        for binding in currently_pending.bindings {
1437            self.dispatch_action_on_node(node_id, binding.action.boxed_clone());
1438            if !self.propagate_event {
1439                return;
1440            }
1441        }
1442
1443        let dispatch_path = self
1444            .window
1445            .rendered_frame
1446            .dispatch_tree
1447            .dispatch_path(node_id);
1448
1449        for keystroke in currently_pending.keystrokes {
1450            let event = KeyDownEvent {
1451                keystroke,
1452                is_held: false,
1453            };
1454
1455            self.dispatch_key_down_up_event(&event, &dispatch_path);
1456            if !self.propagate_event {
1457                return;
1458            }
1459        }
1460
1461        if !input.is_empty() {
1462            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1463                input_handler.dispatch_input(&input, self);
1464                self.window.platform_window.set_input_handler(input_handler)
1465            }
1466        }
1467    }
1468
1469    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: Box<dyn Action>) {
1470        let dispatch_path = self
1471            .window
1472            .rendered_frame
1473            .dispatch_tree
1474            .dispatch_path(node_id);
1475
1476        // Capture phase
1477        for node_id in &dispatch_path {
1478            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1479            for DispatchActionListener {
1480                action_type,
1481                listener,
1482            } in node.action_listeners.clone()
1483            {
1484                let any_action = action.as_any();
1485                if action_type == any_action.type_id() {
1486                    self.with_element_context(|cx| {
1487                        listener(any_action, DispatchPhase::Capture, cx);
1488                    });
1489
1490                    if !self.propagate_event {
1491                        return;
1492                    }
1493                }
1494            }
1495        }
1496        // Bubble phase
1497        for node_id in dispatch_path.iter().rev() {
1498            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1499            for DispatchActionListener {
1500                action_type,
1501                listener,
1502            } in node.action_listeners.clone()
1503            {
1504                let any_action = action.as_any();
1505                if action_type == any_action.type_id() {
1506                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1507
1508                    self.with_element_context(|cx| {
1509                        listener(any_action, DispatchPhase::Bubble, cx);
1510                    });
1511
1512                    if !self.propagate_event {
1513                        return;
1514                    }
1515                }
1516            }
1517        }
1518    }
1519
1520    /// Register the given handler to be invoked whenever the global of the given type
1521    /// is updated.
1522    pub fn observe_global<G: Global>(
1523        &mut self,
1524        f: impl Fn(&mut WindowContext<'_>) + 'static,
1525    ) -> Subscription {
1526        let window_handle = self.window.handle;
1527        let (subscription, activate) = self.global_observers.insert(
1528            TypeId::of::<G>(),
1529            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1530        );
1531        self.app.defer(move |_| activate());
1532        subscription
1533    }
1534
1535    /// Focus the current window and bring it to the foreground at the platform level.
1536    pub fn activate_window(&self) {
1537        self.window.platform_window.activate();
1538    }
1539
1540    /// Minimize the current window at the platform level.
1541    pub fn minimize_window(&self) {
1542        self.window.platform_window.minimize();
1543    }
1544
1545    /// Toggle full screen status on the current window at the platform level.
1546    pub fn toggle_full_screen(&self) {
1547        self.window.platform_window.toggle_full_screen();
1548    }
1549
1550    /// Present a platform dialog.
1551    /// The provided message will be presented, along with buttons for each answer.
1552    /// When a button is clicked, the returned Receiver will receive the index of the clicked button.
1553    pub fn prompt(
1554        &self,
1555        level: PromptLevel,
1556        message: &str,
1557        detail: Option<&str>,
1558        answers: &[&str],
1559    ) -> oneshot::Receiver<usize> {
1560        self.window
1561            .platform_window
1562            .prompt(level, message, detail, answers)
1563    }
1564
1565    /// Returns all available actions for the focused element.
1566    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1567        let node_id = self
1568            .window
1569            .focus
1570            .and_then(|focus_id| {
1571                self.window
1572                    .rendered_frame
1573                    .dispatch_tree
1574                    .focusable_node_id(focus_id)
1575            })
1576            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1577
1578        self.window
1579            .rendered_frame
1580            .dispatch_tree
1581            .available_actions(node_id)
1582    }
1583
1584    /// Returns key bindings that invoke the given action on the currently focused element.
1585    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1586        self.window
1587            .rendered_frame
1588            .dispatch_tree
1589            .bindings_for_action(
1590                action,
1591                &self.window.rendered_frame.dispatch_tree.context_stack,
1592            )
1593    }
1594
1595    /// Returns any bindings that would invoke the given action on the given focus handle if it were focused.
1596    pub fn bindings_for_action_in(
1597        &self,
1598        action: &dyn Action,
1599        focus_handle: &FocusHandle,
1600    ) -> Vec<KeyBinding> {
1601        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1602
1603        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1604            return vec![];
1605        };
1606        let context_stack: Vec<_> = dispatch_tree
1607            .dispatch_path(node_id)
1608            .into_iter()
1609            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1610            .collect();
1611        dispatch_tree.bindings_for_action(action, &context_stack)
1612    }
1613
1614    /// Returns a generic event listener that invokes the given listener with the view and context associated with the given view handle.
1615    pub fn listener_for<V: Render, E>(
1616        &self,
1617        view: &View<V>,
1618        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1619    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1620        let view = view.downgrade();
1621        move |e: &E, cx: &mut WindowContext| {
1622            view.update(cx, |view, cx| f(view, e, cx)).ok();
1623        }
1624    }
1625
1626    /// Returns a generic handler that invokes the given handler with the view and context associated with the given view handle.
1627    pub fn handler_for<V: Render>(
1628        &self,
1629        view: &View<V>,
1630        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1631    ) -> impl Fn(&mut WindowContext) {
1632        let view = view.downgrade();
1633        move |cx: &mut WindowContext| {
1634            view.update(cx, |view, cx| f(view, cx)).ok();
1635        }
1636    }
1637
1638    /// Register a callback that can interrupt the closing of the current window based the returned boolean.
1639    /// If the callback returns false, the window won't be closed.
1640    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1641        let mut this = self.to_async();
1642        self.window
1643            .platform_window
1644            .on_should_close(Box::new(move || this.update(|cx| f(cx)).unwrap_or(true)))
1645    }
1646
1647    pub(crate) fn parent_view_id(&self) -> EntityId {
1648        *self
1649            .window
1650            .next_frame
1651            .view_stack
1652            .last()
1653            .expect("a view should always be on the stack while drawing")
1654    }
1655
1656    /// Register an action listener on the window for the next frame. The type of action
1657    /// is determined by the first parameter of the given listener. When the next frame is rendered
1658    /// the listener will be cleared.
1659    ///
1660    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
1661    /// a specific need to register a global listener.
1662    pub fn on_action(
1663        &mut self,
1664        action_type: TypeId,
1665        listener: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
1666    ) {
1667        self.window
1668            .next_frame
1669            .dispatch_tree
1670            .on_action(action_type, Rc::new(listener));
1671    }
1672}
1673
1674impl Context for WindowContext<'_> {
1675    type Result<T> = T;
1676
1677    fn new_model<T>(&mut self, build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T) -> Model<T>
1678    where
1679        T: 'static,
1680    {
1681        let slot = self.app.entities.reserve();
1682        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1683        self.entities.insert(slot, model)
1684    }
1685
1686    fn update_model<T: 'static, R>(
1687        &mut self,
1688        model: &Model<T>,
1689        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1690    ) -> R {
1691        let mut entity = self.entities.lease(model);
1692        let result = update(
1693            &mut *entity,
1694            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1695        );
1696        self.entities.end_lease(entity);
1697        result
1698    }
1699
1700    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1701    where
1702        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1703    {
1704        if window == self.window.handle {
1705            let root_view = self.window.root_view.clone().unwrap();
1706            Ok(update(root_view, self))
1707        } else {
1708            window.update(self.app, update)
1709        }
1710    }
1711
1712    fn read_model<T, R>(
1713        &self,
1714        handle: &Model<T>,
1715        read: impl FnOnce(&T, &AppContext) -> R,
1716    ) -> Self::Result<R>
1717    where
1718        T: 'static,
1719    {
1720        let entity = self.entities.read(handle);
1721        read(entity, &*self.app)
1722    }
1723
1724    fn read_window<T, R>(
1725        &self,
1726        window: &WindowHandle<T>,
1727        read: impl FnOnce(View<T>, &AppContext) -> R,
1728    ) -> Result<R>
1729    where
1730        T: 'static,
1731    {
1732        if window.any_handle == self.window.handle {
1733            let root_view = self
1734                .window
1735                .root_view
1736                .clone()
1737                .unwrap()
1738                .downcast::<T>()
1739                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1740            Ok(read(root_view, self))
1741        } else {
1742            self.app.read_window(window, read)
1743        }
1744    }
1745}
1746
1747impl VisualContext for WindowContext<'_> {
1748    fn new_view<V>(
1749        &mut self,
1750        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1751    ) -> Self::Result<View<V>>
1752    where
1753        V: 'static + Render,
1754    {
1755        let slot = self.app.entities.reserve();
1756        let view = View {
1757            model: slot.clone(),
1758        };
1759        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1760        let entity = build_view_state(&mut cx);
1761        cx.entities.insert(slot, entity);
1762
1763        // Non-generic part to avoid leaking SubscriberSet to invokers of `new_view`.
1764        fn notify_observers(cx: &mut WindowContext, tid: TypeId, view: AnyView) {
1765            cx.new_view_observers.clone().retain(&tid, |observer| {
1766                let any_view = view.clone();
1767                (observer)(any_view, cx);
1768                true
1769            });
1770        }
1771        notify_observers(self, TypeId::of::<V>(), AnyView::from(view.clone()));
1772
1773        view
1774    }
1775
1776    /// Updates the given view. Prefer calling [`View::update`] instead, which calls this method.
1777    fn update_view<T: 'static, R>(
1778        &mut self,
1779        view: &View<T>,
1780        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1781    ) -> Self::Result<R> {
1782        let mut lease = self.app.entities.lease(&view.model);
1783        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, view);
1784        let result = update(&mut *lease, &mut cx);
1785        cx.app.entities.end_lease(lease);
1786        result
1787    }
1788
1789    fn replace_root_view<V>(
1790        &mut self,
1791        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1792    ) -> Self::Result<View<V>>
1793    where
1794        V: 'static + Render,
1795    {
1796        let view = self.new_view(build_view);
1797        self.window.root_view = Some(view.clone().into());
1798        self.refresh();
1799        view
1800    }
1801
1802    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1803        self.update_view(view, |view, cx| {
1804            view.focus_handle(cx).clone().focus(cx);
1805        })
1806    }
1807
1808    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1809    where
1810        V: ManagedView,
1811    {
1812        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1813    }
1814}
1815
1816impl<'a> std::ops::Deref for WindowContext<'a> {
1817    type Target = AppContext;
1818
1819    fn deref(&self) -> &Self::Target {
1820        self.app
1821    }
1822}
1823
1824impl<'a> std::ops::DerefMut for WindowContext<'a> {
1825    fn deref_mut(&mut self) -> &mut Self::Target {
1826        self.app
1827    }
1828}
1829
1830impl<'a> Borrow<AppContext> for WindowContext<'a> {
1831    fn borrow(&self) -> &AppContext {
1832        self.app
1833    }
1834}
1835
1836impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1837    fn borrow_mut(&mut self) -> &mut AppContext {
1838        self.app
1839    }
1840}
1841
1842/// This trait contains functionality that is shared across [`ViewContext`] and [`WindowContext`]
1843pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1844    #[doc(hidden)]
1845    fn app_mut(&mut self) -> &mut AppContext {
1846        self.borrow_mut()
1847    }
1848
1849    #[doc(hidden)]
1850    fn app(&self) -> &AppContext {
1851        self.borrow()
1852    }
1853
1854    #[doc(hidden)]
1855    fn window(&self) -> &Window {
1856        self.borrow()
1857    }
1858
1859    #[doc(hidden)]
1860    fn window_mut(&mut self) -> &mut Window {
1861        self.borrow_mut()
1862    }
1863}
1864
1865impl Borrow<Window> for WindowContext<'_> {
1866    fn borrow(&self) -> &Window {
1867        self.window
1868    }
1869}
1870
1871impl BorrowMut<Window> for WindowContext<'_> {
1872    fn borrow_mut(&mut self) -> &mut Window {
1873        self.window
1874    }
1875}
1876
1877impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
1878
1879/// Provides access to application state that is specialized for a particular [`View`].
1880/// Allows you to interact with focus, emit events, etc.
1881/// ViewContext also derefs to [`WindowContext`], giving you access to all of its methods as well.
1882/// When you call [`View::update`], you're passed a `&mut V` and an `&mut ViewContext<V>`.
1883pub struct ViewContext<'a, V> {
1884    window_cx: WindowContext<'a>,
1885    view: &'a View<V>,
1886}
1887
1888impl<V> Borrow<AppContext> for ViewContext<'_, V> {
1889    fn borrow(&self) -> &AppContext {
1890        &*self.window_cx.app
1891    }
1892}
1893
1894impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
1895    fn borrow_mut(&mut self) -> &mut AppContext {
1896        &mut *self.window_cx.app
1897    }
1898}
1899
1900impl<V> Borrow<Window> for ViewContext<'_, V> {
1901    fn borrow(&self) -> &Window {
1902        &*self.window_cx.window
1903    }
1904}
1905
1906impl<V> BorrowMut<Window> for ViewContext<'_, V> {
1907    fn borrow_mut(&mut self) -> &mut Window {
1908        &mut *self.window_cx.window
1909    }
1910}
1911
1912impl<'a, V: 'static> ViewContext<'a, V> {
1913    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
1914        Self {
1915            window_cx: WindowContext::new(app, window),
1916            view,
1917        }
1918    }
1919
1920    /// Get the entity_id of this view.
1921    pub fn entity_id(&self) -> EntityId {
1922        self.view.entity_id()
1923    }
1924
1925    /// Get the view pointer underlying this context.
1926    pub fn view(&self) -> &View<V> {
1927        self.view
1928    }
1929
1930    /// Get the model underlying this view.
1931    pub fn model(&self) -> &Model<V> {
1932        &self.view.model
1933    }
1934
1935    /// Access the underlying window context.
1936    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
1937        &mut self.window_cx
1938    }
1939
1940    /// Sets a given callback to be run on the next frame.
1941    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
1942    where
1943        V: 'static,
1944    {
1945        let view = self.view().clone();
1946        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
1947    }
1948
1949    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
1950    /// that are currently on the stack to be returned to the app.
1951    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
1952        let view = self.view().downgrade();
1953        self.window_cx.defer(move |cx| {
1954            view.update(cx, f).ok();
1955        });
1956    }
1957
1958    /// Observe another model or view for changes to its state, as tracked by [`ModelContext::notify`].
1959    pub fn observe<V2, E>(
1960        &mut self,
1961        entity: &E,
1962        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
1963    ) -> Subscription
1964    where
1965        V2: 'static,
1966        V: 'static,
1967        E: Entity<V2>,
1968    {
1969        let view = self.view().downgrade();
1970        let entity_id = entity.entity_id();
1971        let entity = entity.downgrade();
1972        let window_handle = self.window.handle;
1973        self.app.new_observer(
1974            entity_id,
1975            Box::new(move |cx| {
1976                window_handle
1977                    .update(cx, |_, cx| {
1978                        if let Some(handle) = E::upgrade_from(&entity) {
1979                            view.update(cx, |this, cx| on_notify(this, handle, cx))
1980                                .is_ok()
1981                        } else {
1982                            false
1983                        }
1984                    })
1985                    .unwrap_or(false)
1986            }),
1987        )
1988    }
1989
1990    /// Subscribe to events emitted by another model or view.
1991    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
1992    /// 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.
1993    pub fn subscribe<V2, E, Evt>(
1994        &mut self,
1995        entity: &E,
1996        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
1997    ) -> Subscription
1998    where
1999        V2: EventEmitter<Evt>,
2000        E: Entity<V2>,
2001        Evt: 'static,
2002    {
2003        let view = self.view().downgrade();
2004        let entity_id = entity.entity_id();
2005        let handle = entity.downgrade();
2006        let window_handle = self.window.handle;
2007        self.app.new_subscription(
2008            entity_id,
2009            (
2010                TypeId::of::<Evt>(),
2011                Box::new(move |event, cx| {
2012                    window_handle
2013                        .update(cx, |_, cx| {
2014                            if let Some(handle) = E::upgrade_from(&handle) {
2015                                let event = event.downcast_ref().expect("invalid event type");
2016                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2017                                    .is_ok()
2018                            } else {
2019                                false
2020                            }
2021                        })
2022                        .unwrap_or(false)
2023                }),
2024            ),
2025        )
2026    }
2027
2028    /// Register a callback to be invoked when the view is released.
2029    ///
2030    /// The callback receives a handle to the view's window. This handle may be
2031    /// invalid, if the window was closed before the view was released.
2032    pub fn on_release(
2033        &mut self,
2034        on_release: impl FnOnce(&mut V, AnyWindowHandle, &mut AppContext) + 'static,
2035    ) -> Subscription {
2036        let window_handle = self.window.handle;
2037        let (subscription, activate) = self.app.release_listeners.insert(
2038            self.view.model.entity_id,
2039            Box::new(move |this, cx| {
2040                let this = this.downcast_mut().expect("invalid entity type");
2041                on_release(this, window_handle, cx)
2042            }),
2043        );
2044        activate();
2045        subscription
2046    }
2047
2048    /// Register a callback to be invoked when the given Model or View is released.
2049    pub fn observe_release<V2, E>(
2050        &mut self,
2051        entity: &E,
2052        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2053    ) -> Subscription
2054    where
2055        V: 'static,
2056        V2: 'static,
2057        E: Entity<V2>,
2058    {
2059        let view = self.view().downgrade();
2060        let entity_id = entity.entity_id();
2061        let window_handle = self.window.handle;
2062        let (subscription, activate) = self.app.release_listeners.insert(
2063            entity_id,
2064            Box::new(move |entity, cx| {
2065                let entity = entity.downcast_mut().expect("invalid entity type");
2066                let _ = window_handle.update(cx, |_, cx| {
2067                    view.update(cx, |this, cx| on_release(this, entity, cx))
2068                });
2069            }),
2070        );
2071        activate();
2072        subscription
2073    }
2074
2075    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
2076    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
2077    pub fn notify(&mut self) {
2078        for view_id in self
2079            .window
2080            .rendered_frame
2081            .dispatch_tree
2082            .view_path(self.view.entity_id())
2083            .into_iter()
2084            .rev()
2085        {
2086            if !self.window.dirty_views.insert(view_id) {
2087                break;
2088            }
2089        }
2090
2091        if !self.window.drawing {
2092            self.window_cx.window.dirty.set(true);
2093            self.window_cx.app.push_effect(Effect::Notify {
2094                emitter: self.view.model.entity_id,
2095            });
2096        }
2097    }
2098
2099    /// Register a callback to be invoked when the window is resized.
2100    pub fn observe_window_bounds(
2101        &mut self,
2102        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2103    ) -> Subscription {
2104        let view = self.view.downgrade();
2105        let (subscription, activate) = self.window.bounds_observers.insert(
2106            (),
2107            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2108        );
2109        activate();
2110        subscription
2111    }
2112
2113    /// Register a callback to be invoked when the window is activated or deactivated.
2114    pub fn observe_window_activation(
2115        &mut self,
2116        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2117    ) -> Subscription {
2118        let view = self.view.downgrade();
2119        let (subscription, activate) = self.window.activation_observers.insert(
2120            (),
2121            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2122        );
2123        activate();
2124        subscription
2125    }
2126
2127    /// Registers a callback to be invoked when the window appearance changes.
2128    pub fn observe_window_appearance(
2129        &mut self,
2130        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2131    ) -> Subscription {
2132        let view = self.view.downgrade();
2133        let (subscription, activate) = self.window.appearance_observers.insert(
2134            (),
2135            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2136        );
2137        activate();
2138        subscription
2139    }
2140
2141    /// Register a listener to be called when the given focus handle receives focus.
2142    /// Returns a subscription and persists until the subscription is dropped.
2143    pub fn on_focus(
2144        &mut self,
2145        handle: &FocusHandle,
2146        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2147    ) -> Subscription {
2148        let view = self.view.downgrade();
2149        let focus_id = handle.id;
2150        let (subscription, activate) =
2151            self.window.new_focus_listener(Box::new(move |event, cx| {
2152                view.update(cx, |view, cx| {
2153                    if event.previous_focus_path.last() != Some(&focus_id)
2154                        && event.current_focus_path.last() == Some(&focus_id)
2155                    {
2156                        listener(view, cx)
2157                    }
2158                })
2159                .is_ok()
2160            }));
2161        self.app.defer(|_| activate());
2162        subscription
2163    }
2164
2165    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2166    /// Returns a subscription and persists until the subscription is dropped.
2167    pub fn on_focus_in(
2168        &mut self,
2169        handle: &FocusHandle,
2170        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2171    ) -> Subscription {
2172        let view = self.view.downgrade();
2173        let focus_id = handle.id;
2174        let (subscription, activate) =
2175            self.window.new_focus_listener(Box::new(move |event, cx| {
2176                view.update(cx, |view, cx| {
2177                    if !event.previous_focus_path.contains(&focus_id)
2178                        && event.current_focus_path.contains(&focus_id)
2179                    {
2180                        listener(view, cx)
2181                    }
2182                })
2183                .is_ok()
2184            }));
2185        self.app.defer(move |_| activate());
2186        subscription
2187    }
2188
2189    /// Register a listener to be called when the given focus handle loses focus.
2190    /// Returns a subscription and persists until the subscription is dropped.
2191    pub fn on_blur(
2192        &mut self,
2193        handle: &FocusHandle,
2194        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2195    ) -> Subscription {
2196        let view = self.view.downgrade();
2197        let focus_id = handle.id;
2198        let (subscription, activate) =
2199            self.window.new_focus_listener(Box::new(move |event, cx| {
2200                view.update(cx, |view, cx| {
2201                    if event.previous_focus_path.last() == Some(&focus_id)
2202                        && event.current_focus_path.last() != Some(&focus_id)
2203                    {
2204                        listener(view, cx)
2205                    }
2206                })
2207                .is_ok()
2208            }));
2209        self.app.defer(move |_| activate());
2210        subscription
2211    }
2212
2213    /// Register a listener to be called when nothing in the window has focus.
2214    /// This typically happens when the node that was focused is removed from the tree,
2215    /// and this callback lets you chose a default place to restore the users focus.
2216    /// Returns a subscription and persists until the subscription is dropped.
2217    pub fn on_focus_lost(
2218        &mut self,
2219        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2220    ) -> Subscription {
2221        let view = self.view.downgrade();
2222        let (subscription, activate) = self.window.focus_lost_listeners.insert(
2223            (),
2224            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2225        );
2226        activate();
2227        subscription
2228    }
2229
2230    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2231    /// Returns a subscription and persists until the subscription is dropped.
2232    pub fn on_focus_out(
2233        &mut self,
2234        handle: &FocusHandle,
2235        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2236    ) -> Subscription {
2237        let view = self.view.downgrade();
2238        let focus_id = handle.id;
2239        let (subscription, activate) =
2240            self.window.new_focus_listener(Box::new(move |event, cx| {
2241                view.update(cx, |view, cx| {
2242                    if event.previous_focus_path.contains(&focus_id)
2243                        && !event.current_focus_path.contains(&focus_id)
2244                    {
2245                        listener(view, cx)
2246                    }
2247                })
2248                .is_ok()
2249            }));
2250        self.app.defer(move |_| activate());
2251        subscription
2252    }
2253
2254    /// Schedule a future to be run asynchronously.
2255    /// The given callback is invoked with a [`WeakView<V>`] to avoid leaking the view for a long-running process.
2256    /// It's also given an [`AsyncWindowContext`], which can be used to access the state of the view across await points.
2257    /// The returned future will be polled on the main thread.
2258    pub fn spawn<Fut, R>(
2259        &mut self,
2260        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2261    ) -> Task<R>
2262    where
2263        R: 'static,
2264        Fut: Future<Output = R> + 'static,
2265    {
2266        let view = self.view().downgrade();
2267        self.window_cx.spawn(|cx| f(view, cx))
2268    }
2269
2270    /// Updates the global state of the given type.
2271    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2272    where
2273        G: Global,
2274    {
2275        let mut global = self.app.lease_global::<G>();
2276        let result = f(&mut global, self);
2277        self.app.end_global_lease(global);
2278        result
2279    }
2280
2281    /// Register a callback to be invoked when the given global state changes.
2282    pub fn observe_global<G: Global>(
2283        &mut self,
2284        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2285    ) -> Subscription {
2286        let window_handle = self.window.handle;
2287        let view = self.view().downgrade();
2288        let (subscription, activate) = self.global_observers.insert(
2289            TypeId::of::<G>(),
2290            Box::new(move |cx| {
2291                window_handle
2292                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2293                    .unwrap_or(false)
2294            }),
2295        );
2296        self.app.defer(move |_| activate());
2297        subscription
2298    }
2299
2300    /// Register a callback to be invoked when the given Action type is dispatched to the window.
2301    pub fn on_action(
2302        &mut self,
2303        action_type: TypeId,
2304        listener: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2305    ) {
2306        let handle = self.view().clone();
2307        self.window_cx
2308            .on_action(action_type, move |action, phase, cx| {
2309                handle.update(cx, |view, cx| {
2310                    listener(view, action, phase, cx);
2311                })
2312            });
2313    }
2314
2315    /// Emit an event to be handled any other views that have subscribed via [ViewContext::subscribe].
2316    pub fn emit<Evt>(&mut self, event: Evt)
2317    where
2318        Evt: 'static,
2319        V: EventEmitter<Evt>,
2320    {
2321        let emitter = self.view.model.entity_id;
2322        self.app.push_effect(Effect::Emit {
2323            emitter,
2324            event_type: TypeId::of::<Evt>(),
2325            event: Box::new(event),
2326        });
2327    }
2328
2329    /// Move focus to the current view, assuming it implements [`FocusableView`].
2330    pub fn focus_self(&mut self)
2331    where
2332        V: FocusableView,
2333    {
2334        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2335    }
2336
2337    /// Convenience method for accessing view state in an event callback.
2338    ///
2339    /// Many GPUI callbacks take the form of `Fn(&E, &mut WindowContext)`,
2340    /// but it's often useful to be able to access view state in these
2341    /// callbacks. This method provides a convenient way to do so.
2342    pub fn listener<E>(
2343        &self,
2344        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2345    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2346        let view = self.view().downgrade();
2347        move |e: &E, cx: &mut WindowContext| {
2348            view.update(cx, |view, cx| f(view, e, cx)).ok();
2349        }
2350    }
2351}
2352
2353impl<V> Context for ViewContext<'_, V> {
2354    type Result<U> = U;
2355
2356    fn new_model<T: 'static>(
2357        &mut self,
2358        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2359    ) -> Model<T> {
2360        self.window_cx.new_model(build_model)
2361    }
2362
2363    fn update_model<T: 'static, R>(
2364        &mut self,
2365        model: &Model<T>,
2366        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2367    ) -> R {
2368        self.window_cx.update_model(model, update)
2369    }
2370
2371    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2372    where
2373        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2374    {
2375        self.window_cx.update_window(window, update)
2376    }
2377
2378    fn read_model<T, R>(
2379        &self,
2380        handle: &Model<T>,
2381        read: impl FnOnce(&T, &AppContext) -> R,
2382    ) -> Self::Result<R>
2383    where
2384        T: 'static,
2385    {
2386        self.window_cx.read_model(handle, read)
2387    }
2388
2389    fn read_window<T, R>(
2390        &self,
2391        window: &WindowHandle<T>,
2392        read: impl FnOnce(View<T>, &AppContext) -> R,
2393    ) -> Result<R>
2394    where
2395        T: 'static,
2396    {
2397        self.window_cx.read_window(window, read)
2398    }
2399}
2400
2401impl<V: 'static> VisualContext for ViewContext<'_, V> {
2402    fn new_view<W: Render + 'static>(
2403        &mut self,
2404        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2405    ) -> Self::Result<View<W>> {
2406        self.window_cx.new_view(build_view_state)
2407    }
2408
2409    fn update_view<V2: 'static, R>(
2410        &mut self,
2411        view: &View<V2>,
2412        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2413    ) -> Self::Result<R> {
2414        self.window_cx.update_view(view, update)
2415    }
2416
2417    fn replace_root_view<W>(
2418        &mut self,
2419        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2420    ) -> Self::Result<View<W>>
2421    where
2422        W: 'static + Render,
2423    {
2424        self.window_cx.replace_root_view(build_view)
2425    }
2426
2427    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2428        self.window_cx.focus_view(view)
2429    }
2430
2431    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2432        self.window_cx.dismiss_view(view)
2433    }
2434}
2435
2436impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2437    type Target = WindowContext<'a>;
2438
2439    fn deref(&self) -> &Self::Target {
2440        &self.window_cx
2441    }
2442}
2443
2444impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2445    fn deref_mut(&mut self) -> &mut Self::Target {
2446        &mut self.window_cx
2447    }
2448}
2449
2450// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2451slotmap::new_key_type! {
2452    /// A unique identifier for a window.
2453    pub struct WindowId;
2454}
2455
2456impl WindowId {
2457    /// Converts this window ID to a `u64`.
2458    pub fn as_u64(&self) -> u64 {
2459        self.0.as_ffi()
2460    }
2461}
2462
2463/// A handle to a window with a specific root view type.
2464/// Note that this does not keep the window alive on its own.
2465#[derive(Deref, DerefMut)]
2466pub struct WindowHandle<V> {
2467    #[deref]
2468    #[deref_mut]
2469    pub(crate) any_handle: AnyWindowHandle,
2470    state_type: PhantomData<V>,
2471}
2472
2473impl<V: 'static + Render> WindowHandle<V> {
2474    /// Creates a new handle from a window ID.
2475    /// This does not check if the root type of the window is `V`.
2476    pub fn new(id: WindowId) -> Self {
2477        WindowHandle {
2478            any_handle: AnyWindowHandle {
2479                id,
2480                state_type: TypeId::of::<V>(),
2481            },
2482            state_type: PhantomData,
2483        }
2484    }
2485
2486    /// Get the root view out of this window.
2487    ///
2488    /// This will fail if the window is closed or if the root view's type does not match `V`.
2489    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2490    where
2491        C: Context,
2492    {
2493        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2494            root_view
2495                .downcast::<V>()
2496                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2497        }))
2498    }
2499
2500    /// Updates the root view of this window.
2501    ///
2502    /// This will fail if the window has been closed or if the root view's type does not match
2503    pub fn update<C, R>(
2504        &self,
2505        cx: &mut C,
2506        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2507    ) -> Result<R>
2508    where
2509        C: Context,
2510    {
2511        cx.update_window(self.any_handle, |root_view, cx| {
2512            let view = root_view
2513                .downcast::<V>()
2514                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2515            Ok(cx.update_view(&view, update))
2516        })?
2517    }
2518
2519    /// Read the root view out of this window.
2520    ///
2521    /// This will fail if the window is closed or if the root view's type does not match `V`.
2522    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2523        let x = cx
2524            .windows
2525            .get(self.id)
2526            .and_then(|window| {
2527                window
2528                    .as_ref()
2529                    .and_then(|window| window.root_view.clone())
2530                    .map(|root_view| root_view.downcast::<V>())
2531            })
2532            .ok_or_else(|| anyhow!("window not found"))?
2533            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2534
2535        Ok(x.read(cx))
2536    }
2537
2538    /// Read the root view out of this window, with a callback
2539    ///
2540    /// This will fail if the window is closed or if the root view's type does not match `V`.
2541    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2542    where
2543        C: Context,
2544    {
2545        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2546    }
2547
2548    /// Read the root view pointer off of this window.
2549    ///
2550    /// This will fail if the window is closed or if the root view's type does not match `V`.
2551    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2552    where
2553        C: Context,
2554    {
2555        cx.read_window(self, |root_view, _cx| root_view.clone())
2556    }
2557
2558    /// Check if this window is 'active'.
2559    ///
2560    /// Will return `None` if the window is closed or currently
2561    /// borrowed.
2562    pub fn is_active(&self, cx: &mut AppContext) -> Option<bool> {
2563        cx.update_window(self.any_handle, |_, cx| cx.is_window_active())
2564            .ok()
2565    }
2566}
2567
2568impl<V> Copy for WindowHandle<V> {}
2569
2570impl<V> Clone for WindowHandle<V> {
2571    fn clone(&self) -> Self {
2572        *self
2573    }
2574}
2575
2576impl<V> PartialEq for WindowHandle<V> {
2577    fn eq(&self, other: &Self) -> bool {
2578        self.any_handle == other.any_handle
2579    }
2580}
2581
2582impl<V> Eq for WindowHandle<V> {}
2583
2584impl<V> Hash for WindowHandle<V> {
2585    fn hash<H: Hasher>(&self, state: &mut H) {
2586        self.any_handle.hash(state);
2587    }
2588}
2589
2590impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle {
2591    fn from(val: WindowHandle<V>) -> Self {
2592        val.any_handle
2593    }
2594}
2595
2596/// A handle to a window with any root view type, which can be downcast to a window with a specific root view type.
2597#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2598pub struct AnyWindowHandle {
2599    pub(crate) id: WindowId,
2600    state_type: TypeId,
2601}
2602
2603impl AnyWindowHandle {
2604    /// Get the ID of this window.
2605    pub fn window_id(&self) -> WindowId {
2606        self.id
2607    }
2608
2609    /// Attempt to convert this handle to a window handle with a specific root view type.
2610    /// If the types do not match, this will return `None`.
2611    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2612        if TypeId::of::<T>() == self.state_type {
2613            Some(WindowHandle {
2614                any_handle: *self,
2615                state_type: PhantomData,
2616            })
2617        } else {
2618            None
2619        }
2620    }
2621
2622    /// Updates the state of the root view of this window.
2623    ///
2624    /// This will fail if the window has been closed.
2625    pub fn update<C, R>(
2626        self,
2627        cx: &mut C,
2628        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2629    ) -> Result<R>
2630    where
2631        C: Context,
2632    {
2633        cx.update_window(self, update)
2634    }
2635
2636    /// Read the state of the root view of this window.
2637    ///
2638    /// This will fail if the window has been closed.
2639    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2640    where
2641        C: Context,
2642        T: 'static,
2643    {
2644        let view = self
2645            .downcast::<T>()
2646            .context("the type of the window's root view has changed")?;
2647
2648        cx.read_window(&view, read)
2649    }
2650}
2651
2652/// An identifier for an [`Element`](crate::Element).
2653///
2654/// Can be constructed with a string, a number, or both, as well
2655/// as other internal representations.
2656#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2657pub enum ElementId {
2658    /// The ID of a View element
2659    View(EntityId),
2660    /// An integer ID.
2661    Integer(usize),
2662    /// A string based ID.
2663    Name(SharedString),
2664    /// An ID that's equated with a focus handle.
2665    FocusHandle(FocusId),
2666    /// A combination of a name and an integer.
2667    NamedInteger(SharedString, usize),
2668}
2669
2670impl Display for ElementId {
2671    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
2672        match self {
2673            ElementId::View(entity_id) => write!(f, "view-{}", entity_id)?,
2674            ElementId::Integer(ix) => write!(f, "{}", ix)?,
2675            ElementId::Name(name) => write!(f, "{}", name)?,
2676            ElementId::FocusHandle(_) => write!(f, "FocusHandle")?,
2677            ElementId::NamedInteger(s, i) => write!(f, "{}-{}", s, i)?,
2678        }
2679
2680        Ok(())
2681    }
2682}
2683
2684impl ElementId {
2685    pub(crate) fn from_entity_id(entity_id: EntityId) -> Self {
2686        ElementId::View(entity_id)
2687    }
2688}
2689
2690impl TryInto<SharedString> for ElementId {
2691    type Error = anyhow::Error;
2692
2693    fn try_into(self) -> anyhow::Result<SharedString> {
2694        if let ElementId::Name(name) = self {
2695            Ok(name)
2696        } else {
2697            Err(anyhow!("element id is not string"))
2698        }
2699    }
2700}
2701
2702impl From<usize> for ElementId {
2703    fn from(id: usize) -> Self {
2704        ElementId::Integer(id)
2705    }
2706}
2707
2708impl From<i32> for ElementId {
2709    fn from(id: i32) -> Self {
2710        Self::Integer(id as usize)
2711    }
2712}
2713
2714impl From<SharedString> for ElementId {
2715    fn from(name: SharedString) -> Self {
2716        ElementId::Name(name)
2717    }
2718}
2719
2720impl From<&'static str> for ElementId {
2721    fn from(name: &'static str) -> Self {
2722        ElementId::Name(name.into())
2723    }
2724}
2725
2726impl<'a> From<&'a FocusHandle> for ElementId {
2727    fn from(handle: &'a FocusHandle) -> Self {
2728        ElementId::FocusHandle(handle.id)
2729    }
2730}
2731
2732impl From<(&'static str, EntityId)> for ElementId {
2733    fn from((name, id): (&'static str, EntityId)) -> Self {
2734        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2735    }
2736}
2737
2738impl From<(&'static str, usize)> for ElementId {
2739    fn from((name, id): (&'static str, usize)) -> Self {
2740        ElementId::NamedInteger(name.into(), id)
2741    }
2742}
2743
2744impl From<(&'static str, u64)> for ElementId {
2745    fn from((name, id): (&'static str, u64)) -> Self {
2746        ElementId::NamedInteger(name.into(), id as usize)
2747    }
2748}
2749
2750/// A rectangle to be rendered in the window at the given position and size.
2751/// Passed as an argument [`ElementContext::paint_quad`].
2752#[derive(Clone)]
2753pub struct PaintQuad {
2754    bounds: Bounds<Pixels>,
2755    corner_radii: Corners<Pixels>,
2756    background: Hsla,
2757    border_widths: Edges<Pixels>,
2758    border_color: Hsla,
2759}
2760
2761impl PaintQuad {
2762    /// Sets the corner radii of the quad.
2763    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
2764        PaintQuad {
2765            corner_radii: corner_radii.into(),
2766            ..self
2767        }
2768    }
2769
2770    /// Sets the border widths of the quad.
2771    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
2772        PaintQuad {
2773            border_widths: border_widths.into(),
2774            ..self
2775        }
2776    }
2777
2778    /// Sets the border color of the quad.
2779    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
2780        PaintQuad {
2781            border_color: border_color.into(),
2782            ..self
2783        }
2784    }
2785
2786    /// Sets the background color of the quad.
2787    pub fn background(self, background: impl Into<Hsla>) -> Self {
2788        PaintQuad {
2789            background: background.into(),
2790            ..self
2791        }
2792    }
2793}
2794
2795/// Creates a quad with the given parameters.
2796pub fn quad(
2797    bounds: Bounds<Pixels>,
2798    corner_radii: impl Into<Corners<Pixels>>,
2799    background: impl Into<Hsla>,
2800    border_widths: impl Into<Edges<Pixels>>,
2801    border_color: impl Into<Hsla>,
2802) -> PaintQuad {
2803    PaintQuad {
2804        bounds,
2805        corner_radii: corner_radii.into(),
2806        background: background.into(),
2807        border_widths: border_widths.into(),
2808        border_color: border_color.into(),
2809    }
2810}
2811
2812/// Creates a filled quad with the given bounds and background color.
2813pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
2814    PaintQuad {
2815        bounds: bounds.into(),
2816        corner_radii: (0.).into(),
2817        background: background.into(),
2818        border_widths: (0.).into(),
2819        border_color: transparent_black(),
2820    }
2821}
2822
2823/// Creates a rectangle outline with the given bounds, border color, and a 1px border width
2824pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
2825    PaintQuad {
2826        bounds: bounds.into(),
2827        corner_radii: (0.).into(),
2828        background: transparent_black(),
2829        border_widths: (1.).into(),
2830        border_color: border_color.into(),
2831    }
2832}