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