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    pub fn draw(&mut self) {
 954        self.window.dirty.set(false);
 955        self.window.drawing = true;
 956
 957        if let Some(requested_handler) = self.window.rendered_frame.requested_input_handler.as_mut()
 958        {
 959            let input_handler = self.window.platform_window.take_input_handler();
 960            requested_handler.handler = input_handler;
 961        }
 962
 963        let root_view = self.window.root_view.take().unwrap();
 964        self.with_element_context(|cx| {
 965            cx.with_z_index(0, |cx| {
 966                cx.with_key_dispatch(Some(KeyContext::default()), None, |_, cx| {
 967                    // We need to use cx.cx here so we can utilize borrow splitting
 968                    for (action_type, action_listeners) in &cx.cx.app.global_action_listeners {
 969                        for action_listener in action_listeners.iter().cloned() {
 970                            cx.cx.window.next_frame.dispatch_tree.on_action(
 971                                *action_type,
 972                                Rc::new(
 973                                    move |action: &dyn Any, phase, cx: &mut WindowContext<'_>| {
 974                                        action_listener(action, phase, cx)
 975                                    },
 976                                ),
 977                            )
 978                        }
 979                    }
 980
 981                    let available_space = cx.window.viewport_size.map(Into::into);
 982                    root_view.draw(Point::default(), available_space, cx);
 983                })
 984            })
 985        });
 986
 987        if let Some(active_drag) = self.app.active_drag.take() {
 988            self.with_element_context(|cx| {
 989                cx.with_z_index(ACTIVE_DRAG_Z_INDEX, |cx| {
 990                    let offset = cx.mouse_position() - active_drag.cursor_offset;
 991                    let available_space =
 992                        size(AvailableSpace::MinContent, AvailableSpace::MinContent);
 993                    active_drag.view.draw(offset, available_space, cx);
 994                })
 995            });
 996            self.active_drag = Some(active_drag);
 997        } else if let Some(tooltip_request) = self.window.next_frame.tooltip_request.take() {
 998            self.with_element_context(|cx| {
 999                cx.with_z_index(1, |cx| {
1000                    let available_space =
1001                        size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1002                    tooltip_request.tooltip.view.draw(
1003                        tooltip_request.tooltip.cursor_offset,
1004                        available_space,
1005                        cx,
1006                    );
1007                })
1008            });
1009            self.window.next_frame.tooltip_request = Some(tooltip_request);
1010        }
1011        self.window.dirty_views.clear();
1012
1013        self.window
1014            .next_frame
1015            .dispatch_tree
1016            .preserve_pending_keystrokes(
1017                &mut self.window.rendered_frame.dispatch_tree,
1018                self.window.focus,
1019            );
1020        self.window.next_frame.focus = self.window.focus;
1021        self.window.next_frame.window_active = self.window.active.get();
1022        self.window.root_view = Some(root_view);
1023
1024        // Set the cursor only if we're the active window.
1025        let cursor_style = self
1026            .window
1027            .next_frame
1028            .requested_cursor_style
1029            .take()
1030            .unwrap_or(CursorStyle::Arrow);
1031        if self.is_window_active() {
1032            self.platform.set_cursor_style(cursor_style);
1033        }
1034
1035        // Register requested input handler with the platform window.
1036        if let Some(requested_input) = self.window.next_frame.requested_input_handler.as_mut() {
1037            if let Some(handler) = requested_input.handler.take() {
1038                self.window.platform_window.set_input_handler(handler);
1039            }
1040        }
1041
1042        self.window.layout_engine.as_mut().unwrap().clear();
1043        self.text_system()
1044            .finish_frame(&self.window.next_frame.reused_views);
1045        self.window
1046            .next_frame
1047            .finish(&mut self.window.rendered_frame);
1048        ELEMENT_ARENA.with_borrow_mut(|element_arena| {
1049            let percentage = (element_arena.len() as f32 / element_arena.capacity() as f32) * 100.;
1050            if percentage >= 80. {
1051                log::warn!("elevated element arena occupation: {}.", percentage);
1052            }
1053            element_arena.clear();
1054        });
1055
1056        let previous_focus_path = self.window.rendered_frame.focus_path();
1057        let previous_window_active = self.window.rendered_frame.window_active;
1058        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1059        self.window.next_frame.clear();
1060        let current_focus_path = self.window.rendered_frame.focus_path();
1061        let current_window_active = self.window.rendered_frame.window_active;
1062
1063        if previous_focus_path != current_focus_path
1064            || previous_window_active != current_window_active
1065        {
1066            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1067                self.window
1068                    .focus_lost_listeners
1069                    .clone()
1070                    .retain(&(), |listener| listener(self));
1071            }
1072
1073            let event = FocusEvent {
1074                previous_focus_path: if previous_window_active {
1075                    previous_focus_path
1076                } else {
1077                    Default::default()
1078                },
1079                current_focus_path: if current_window_active {
1080                    current_focus_path
1081                } else {
1082                    Default::default()
1083                },
1084            };
1085            self.window
1086                .focus_listeners
1087                .clone()
1088                .retain(&(), |listener| listener(&event, self));
1089        }
1090        self.window.refreshing = false;
1091        self.window.drawing = false;
1092        self.window.needs_present.set(true);
1093    }
1094
1095    fn present(&self) {
1096        self.window
1097            .platform_window
1098            .draw(&self.window.rendered_frame.scene);
1099        self.window.needs_present.set(false);
1100    }
1101
1102    /// Dispatch a given keystroke as though the user had typed it.
1103    /// You can create a keystroke with Keystroke::parse("").
1104    pub fn dispatch_keystroke(&mut self, mut keystroke: Keystroke) -> bool {
1105        if keystroke.ime_key.is_none()
1106            && !keystroke.modifiers.command
1107            && !keystroke.modifiers.control
1108            && !keystroke.modifiers.function
1109        {
1110            keystroke.ime_key = Some(if keystroke.modifiers.shift {
1111                keystroke.key.to_uppercase().clone()
1112            } else {
1113                keystroke.key.clone()
1114            })
1115        }
1116        if self.dispatch_event(PlatformInput::KeyDown(KeyDownEvent {
1117            keystroke: keystroke.clone(),
1118            is_held: false,
1119        })) {
1120            return true;
1121        }
1122
1123        if let Some(input) = keystroke.ime_key {
1124            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1125                input_handler.dispatch_input(&input, self);
1126                self.window.platform_window.set_input_handler(input_handler);
1127                return true;
1128            }
1129        }
1130
1131        false
1132    }
1133
1134    /// Dispatch a mouse or keyboard event on the window.
1135    pub fn dispatch_event(&mut self, event: PlatformInput) -> bool {
1136        self.window.last_input_timestamp.set(Instant::now());
1137        // Handlers may set this to false by calling `stop_propagation`.
1138        self.app.propagate_event = true;
1139        // Handlers may set this to true by calling `prevent_default`.
1140        self.window.default_prevented = false;
1141
1142        let event = match event {
1143            // Track the mouse position with our own state, since accessing the platform
1144            // API for the mouse position can only occur on the main thread.
1145            PlatformInput::MouseMove(mouse_move) => {
1146                self.window.mouse_position = mouse_move.position;
1147                self.window.modifiers = mouse_move.modifiers;
1148                PlatformInput::MouseMove(mouse_move)
1149            }
1150            PlatformInput::MouseDown(mouse_down) => {
1151                self.window.mouse_position = mouse_down.position;
1152                self.window.modifiers = mouse_down.modifiers;
1153                PlatformInput::MouseDown(mouse_down)
1154            }
1155            PlatformInput::MouseUp(mouse_up) => {
1156                self.window.mouse_position = mouse_up.position;
1157                self.window.modifiers = mouse_up.modifiers;
1158                PlatformInput::MouseUp(mouse_up)
1159            }
1160            PlatformInput::MouseExited(mouse_exited) => {
1161                self.window.modifiers = mouse_exited.modifiers;
1162                PlatformInput::MouseExited(mouse_exited)
1163            }
1164            PlatformInput::ModifiersChanged(modifiers_changed) => {
1165                self.window.modifiers = modifiers_changed.modifiers;
1166                PlatformInput::ModifiersChanged(modifiers_changed)
1167            }
1168            PlatformInput::ScrollWheel(scroll_wheel) => {
1169                self.window.mouse_position = scroll_wheel.position;
1170                self.window.modifiers = scroll_wheel.modifiers;
1171                PlatformInput::ScrollWheel(scroll_wheel)
1172            }
1173            // Translate dragging and dropping of external files from the operating system
1174            // to internal drag and drop events.
1175            PlatformInput::FileDrop(file_drop) => match file_drop {
1176                FileDropEvent::Entered { position, paths } => {
1177                    self.window.mouse_position = position;
1178                    if self.active_drag.is_none() {
1179                        self.active_drag = Some(AnyDrag {
1180                            value: Box::new(paths.clone()),
1181                            view: self.new_view(|_| paths).into(),
1182                            cursor_offset: position,
1183                        });
1184                    }
1185                    PlatformInput::MouseMove(MouseMoveEvent {
1186                        position,
1187                        pressed_button: Some(MouseButton::Left),
1188                        modifiers: Modifiers::default(),
1189                    })
1190                }
1191                FileDropEvent::Pending { position } => {
1192                    self.window.mouse_position = position;
1193                    PlatformInput::MouseMove(MouseMoveEvent {
1194                        position,
1195                        pressed_button: Some(MouseButton::Left),
1196                        modifiers: Modifiers::default(),
1197                    })
1198                }
1199                FileDropEvent::Submit { position } => {
1200                    self.activate(true);
1201                    self.window.mouse_position = position;
1202                    PlatformInput::MouseUp(MouseUpEvent {
1203                        button: MouseButton::Left,
1204                        position,
1205                        modifiers: Modifiers::default(),
1206                        click_count: 1,
1207                    })
1208                }
1209                FileDropEvent::Exited => PlatformInput::MouseUp(MouseUpEvent {
1210                    button: MouseButton::Left,
1211                    position: Point::default(),
1212                    modifiers: Modifiers::default(),
1213                    click_count: 1,
1214                }),
1215            },
1216            PlatformInput::KeyDown(_) | PlatformInput::KeyUp(_) => event,
1217        };
1218
1219        if let Some(any_mouse_event) = event.mouse_event() {
1220            self.dispatch_mouse_event(any_mouse_event);
1221        } else if let Some(any_key_event) = event.keyboard_event() {
1222            self.dispatch_key_event(any_key_event);
1223        }
1224
1225        !self.app.propagate_event
1226    }
1227
1228    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1229        if let Some(mut handlers) = self
1230            .window
1231            .rendered_frame
1232            .mouse_listeners
1233            .remove(&event.type_id())
1234        {
1235            // Because handlers may add other handlers, we sort every time.
1236            handlers.sort_by(|(a, _, _), (b, _, _)| a.cmp(b));
1237
1238            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1239            // special purposes, such as detecting events outside of a given Bounds.
1240            for (_, _, handler) in &mut handlers {
1241                self.with_element_context(|cx| {
1242                    handler(event, DispatchPhase::Capture, cx);
1243                });
1244                if !self.app.propagate_event {
1245                    break;
1246                }
1247            }
1248
1249            // Bubble phase, where most normal handlers do their work.
1250            if self.app.propagate_event {
1251                for (_, _, handler) in handlers.iter_mut().rev() {
1252                    self.with_element_context(|cx| {
1253                        handler(event, DispatchPhase::Bubble, cx);
1254                    });
1255                    if !self.app.propagate_event {
1256                        break;
1257                    }
1258                }
1259            }
1260
1261            self.window
1262                .rendered_frame
1263                .mouse_listeners
1264                .insert(event.type_id(), handlers);
1265        }
1266
1267        if self.app.propagate_event && self.has_active_drag() {
1268            if event.is::<MouseMoveEvent>() {
1269                // If this was a mouse move event, redraw the window so that the
1270                // active drag can follow the mouse cursor.
1271                self.refresh();
1272            } else if event.is::<MouseUpEvent>() {
1273                // If this was a mouse up event, cancel the active drag and redraw
1274                // the window.
1275                self.active_drag = None;
1276                self.refresh();
1277            }
1278        }
1279    }
1280
1281    fn dispatch_key_event(&mut self, event: &dyn Any) {
1282        if self.window.dirty.get() {
1283            self.draw();
1284        }
1285
1286        let node_id = self
1287            .window
1288            .focus
1289            .and_then(|focus_id| {
1290                self.window
1291                    .rendered_frame
1292                    .dispatch_tree
1293                    .focusable_node_id(focus_id)
1294            })
1295            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1296
1297        let dispatch_path = self
1298            .window
1299            .rendered_frame
1300            .dispatch_tree
1301            .dispatch_path(node_id);
1302
1303        if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1304            let KeymatchResult { bindings, pending } = self
1305                .window
1306                .rendered_frame
1307                .dispatch_tree
1308                .dispatch_key(&key_down_event.keystroke, &dispatch_path);
1309
1310            if pending {
1311                let mut currently_pending = self.window.pending_input.take().unwrap_or_default();
1312                if currently_pending.focus.is_some() && currently_pending.focus != self.window.focus
1313                {
1314                    currently_pending = PendingInput::default();
1315                }
1316                currently_pending.focus = self.window.focus;
1317                currently_pending
1318                    .keystrokes
1319                    .push(key_down_event.keystroke.clone());
1320                for binding in bindings {
1321                    currently_pending.bindings.push(binding);
1322                }
1323
1324                currently_pending.timer = Some(self.spawn(|mut cx| async move {
1325                    cx.background_executor.timer(Duration::from_secs(1)).await;
1326                    cx.update(move |cx| {
1327                        cx.clear_pending_keystrokes();
1328                        let Some(currently_pending) = cx.window.pending_input.take() else {
1329                            return;
1330                        };
1331                        cx.replay_pending_input(currently_pending)
1332                    })
1333                    .log_err();
1334                }));
1335                self.window.pending_input = Some(currently_pending);
1336
1337                self.propagate_event = false;
1338                return;
1339            } else if let Some(currently_pending) = self.window.pending_input.take() {
1340                if bindings
1341                    .iter()
1342                    .all(|binding| !currently_pending.used_by_binding(binding))
1343                {
1344                    self.replay_pending_input(currently_pending)
1345                }
1346            }
1347
1348            if !bindings.is_empty() {
1349                self.clear_pending_keystrokes();
1350            }
1351
1352            self.propagate_event = true;
1353            for binding in bindings {
1354                self.dispatch_action_on_node(node_id, binding.action.boxed_clone());
1355                if !self.propagate_event {
1356                    self.dispatch_keystroke_observers(event, Some(binding.action));
1357                    return;
1358                }
1359            }
1360        }
1361
1362        self.dispatch_key_down_up_event(event, &dispatch_path);
1363        if !self.propagate_event {
1364            return;
1365        }
1366
1367        self.dispatch_keystroke_observers(event, None);
1368    }
1369
1370    fn dispatch_key_down_up_event(
1371        &mut self,
1372        event: &dyn Any,
1373        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1374    ) {
1375        // Capture phase
1376        for node_id in dispatch_path {
1377            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1378
1379            for key_listener in node.key_listeners.clone() {
1380                self.with_element_context(|cx| {
1381                    key_listener(event, DispatchPhase::Capture, cx);
1382                });
1383                if !self.propagate_event {
1384                    return;
1385                }
1386            }
1387        }
1388
1389        // Bubble phase
1390        for node_id in dispatch_path.iter().rev() {
1391            // Handle low level key events
1392            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1393            for key_listener in node.key_listeners.clone() {
1394                self.with_element_context(|cx| {
1395                    key_listener(event, DispatchPhase::Bubble, cx);
1396                });
1397                if !self.propagate_event {
1398                    return;
1399                }
1400            }
1401        }
1402    }
1403
1404    /// Determine whether a potential multi-stroke key binding is in progress on this window.
1405    pub fn has_pending_keystrokes(&self) -> bool {
1406        self.window
1407            .rendered_frame
1408            .dispatch_tree
1409            .has_pending_keystrokes()
1410    }
1411
1412    fn replay_pending_input(&mut self, currently_pending: PendingInput) {
1413        let node_id = self
1414            .window
1415            .focus
1416            .and_then(|focus_id| {
1417                self.window
1418                    .rendered_frame
1419                    .dispatch_tree
1420                    .focusable_node_id(focus_id)
1421            })
1422            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1423
1424        if self.window.focus != currently_pending.focus {
1425            return;
1426        }
1427
1428        let input = currently_pending.input();
1429
1430        self.propagate_event = true;
1431        for binding in currently_pending.bindings {
1432            self.dispatch_action_on_node(node_id, binding.action.boxed_clone());
1433            if !self.propagate_event {
1434                return;
1435            }
1436        }
1437
1438        let dispatch_path = self
1439            .window
1440            .rendered_frame
1441            .dispatch_tree
1442            .dispatch_path(node_id);
1443
1444        for keystroke in currently_pending.keystrokes {
1445            let event = KeyDownEvent {
1446                keystroke,
1447                is_held: false,
1448            };
1449
1450            self.dispatch_key_down_up_event(&event, &dispatch_path);
1451            if !self.propagate_event {
1452                return;
1453            }
1454        }
1455
1456        if !input.is_empty() {
1457            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1458                input_handler.dispatch_input(&input, self);
1459                self.window.platform_window.set_input_handler(input_handler)
1460            }
1461        }
1462    }
1463
1464    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: Box<dyn Action>) {
1465        let dispatch_path = self
1466            .window
1467            .rendered_frame
1468            .dispatch_tree
1469            .dispatch_path(node_id);
1470
1471        // Capture phase
1472        for node_id in &dispatch_path {
1473            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1474            for DispatchActionListener {
1475                action_type,
1476                listener,
1477            } in node.action_listeners.clone()
1478            {
1479                let any_action = action.as_any();
1480                if action_type == any_action.type_id() {
1481                    self.with_element_context(|cx| {
1482                        listener(any_action, DispatchPhase::Capture, cx);
1483                    });
1484
1485                    if !self.propagate_event {
1486                        return;
1487                    }
1488                }
1489            }
1490        }
1491        // Bubble phase
1492        for node_id in dispatch_path.iter().rev() {
1493            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1494            for DispatchActionListener {
1495                action_type,
1496                listener,
1497            } in node.action_listeners.clone()
1498            {
1499                let any_action = action.as_any();
1500                if action_type == any_action.type_id() {
1501                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1502
1503                    self.with_element_context(|cx| {
1504                        listener(any_action, DispatchPhase::Bubble, cx);
1505                    });
1506
1507                    if !self.propagate_event {
1508                        return;
1509                    }
1510                }
1511            }
1512        }
1513    }
1514
1515    /// Toggle the graphics profiler to debug your application's rendering performance.
1516    pub fn toggle_graphics_profiler(&mut self) {
1517        self.window.graphics_profiler_enabled = !self.window.graphics_profiler_enabled;
1518        self.window
1519            .platform_window
1520            .set_graphics_profiler_enabled(self.window.graphics_profiler_enabled);
1521    }
1522
1523    /// Register the given handler to be invoked whenever the global of the given type
1524    /// is updated.
1525    pub fn observe_global<G: Global>(
1526        &mut self,
1527        f: impl Fn(&mut WindowContext<'_>) + 'static,
1528    ) -> Subscription {
1529        let window_handle = self.window.handle;
1530        let (subscription, activate) = self.global_observers.insert(
1531            TypeId::of::<G>(),
1532            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1533        );
1534        self.app.defer(move |_| activate());
1535        subscription
1536    }
1537
1538    /// Focus the current window and bring it to the foreground at the platform level.
1539    pub fn activate_window(&self) {
1540        self.window.platform_window.activate();
1541    }
1542
1543    /// Minimize the current window at the platform level.
1544    pub fn minimize_window(&self) {
1545        self.window.platform_window.minimize();
1546    }
1547
1548    /// Toggle full screen status on the current window at the platform level.
1549    pub fn toggle_full_screen(&self) {
1550        self.window.platform_window.toggle_full_screen();
1551    }
1552
1553    /// Present a platform dialog.
1554    /// The provided message will be presented, along with buttons for each answer.
1555    /// When a button is clicked, the returned Receiver will receive the index of the clicked button.
1556    pub fn prompt(
1557        &self,
1558        level: PromptLevel,
1559        message: &str,
1560        detail: Option<&str>,
1561        answers: &[&str],
1562    ) -> oneshot::Receiver<usize> {
1563        self.window
1564            .platform_window
1565            .prompt(level, message, detail, answers)
1566    }
1567
1568    /// Returns all available actions for the focused element.
1569    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1570        let node_id = self
1571            .window
1572            .focus
1573            .and_then(|focus_id| {
1574                self.window
1575                    .rendered_frame
1576                    .dispatch_tree
1577                    .focusable_node_id(focus_id)
1578            })
1579            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1580
1581        self.window
1582            .rendered_frame
1583            .dispatch_tree
1584            .available_actions(node_id)
1585    }
1586
1587    /// Returns key bindings that invoke the given action on the currently focused element.
1588    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1589        self.window
1590            .rendered_frame
1591            .dispatch_tree
1592            .bindings_for_action(
1593                action,
1594                &self.window.rendered_frame.dispatch_tree.context_stack,
1595            )
1596    }
1597
1598    /// Returns any bindings that would invoke the given action on the given focus handle if it were focused.
1599    pub fn bindings_for_action_in(
1600        &self,
1601        action: &dyn Action,
1602        focus_handle: &FocusHandle,
1603    ) -> Vec<KeyBinding> {
1604        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1605
1606        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1607            return vec![];
1608        };
1609        let context_stack: Vec<_> = dispatch_tree
1610            .dispatch_path(node_id)
1611            .into_iter()
1612            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1613            .collect();
1614        dispatch_tree.bindings_for_action(action, &context_stack)
1615    }
1616
1617    /// Returns a generic event listener that invokes the given listener with the view and context associated with the given view handle.
1618    pub fn listener_for<V: Render, E>(
1619        &self,
1620        view: &View<V>,
1621        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1622    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1623        let view = view.downgrade();
1624        move |e: &E, cx: &mut WindowContext| {
1625            view.update(cx, |view, cx| f(view, e, cx)).ok();
1626        }
1627    }
1628
1629    /// Returns a generic handler that invokes the given handler with the view and context associated with the given view handle.
1630    pub fn handler_for<V: Render>(
1631        &self,
1632        view: &View<V>,
1633        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1634    ) -> impl Fn(&mut WindowContext) {
1635        let view = view.downgrade();
1636        move |cx: &mut WindowContext| {
1637            view.update(cx, |view, cx| f(view, cx)).ok();
1638        }
1639    }
1640
1641    /// Register a callback that can interrupt the closing of the current window based the returned boolean.
1642    /// If the callback returns false, the window won't be closed.
1643    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1644        let mut this = self.to_async();
1645        self.window
1646            .platform_window
1647            .on_should_close(Box::new(move || this.update(|cx| f(cx)).unwrap_or(true)))
1648    }
1649
1650    pub(crate) fn parent_view_id(&self) -> EntityId {
1651        *self
1652            .window
1653            .next_frame
1654            .view_stack
1655            .last()
1656            .expect("a view should always be on the stack while drawing")
1657    }
1658
1659    /// Register an action listener on the window for the next frame. The type of action
1660    /// is determined by the first parameter of the given listener. When the next frame is rendered
1661    /// the listener will be cleared.
1662    ///
1663    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
1664    /// a specific need to register a global listener.
1665    pub fn on_action(
1666        &mut self,
1667        action_type: TypeId,
1668        listener: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
1669    ) {
1670        self.window
1671            .next_frame
1672            .dispatch_tree
1673            .on_action(action_type, Rc::new(listener));
1674    }
1675}
1676
1677impl Context for WindowContext<'_> {
1678    type Result<T> = T;
1679
1680    fn new_model<T>(&mut self, build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T) -> Model<T>
1681    where
1682        T: 'static,
1683    {
1684        let slot = self.app.entities.reserve();
1685        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1686        self.entities.insert(slot, model)
1687    }
1688
1689    fn update_model<T: 'static, R>(
1690        &mut self,
1691        model: &Model<T>,
1692        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1693    ) -> R {
1694        let mut entity = self.entities.lease(model);
1695        let result = update(
1696            &mut *entity,
1697            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1698        );
1699        self.entities.end_lease(entity);
1700        result
1701    }
1702
1703    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1704    where
1705        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1706    {
1707        if window == self.window.handle {
1708            let root_view = self.window.root_view.clone().unwrap();
1709            Ok(update(root_view, self))
1710        } else {
1711            window.update(self.app, update)
1712        }
1713    }
1714
1715    fn read_model<T, R>(
1716        &self,
1717        handle: &Model<T>,
1718        read: impl FnOnce(&T, &AppContext) -> R,
1719    ) -> Self::Result<R>
1720    where
1721        T: 'static,
1722    {
1723        let entity = self.entities.read(handle);
1724        read(entity, &*self.app)
1725    }
1726
1727    fn read_window<T, R>(
1728        &self,
1729        window: &WindowHandle<T>,
1730        read: impl FnOnce(View<T>, &AppContext) -> R,
1731    ) -> Result<R>
1732    where
1733        T: 'static,
1734    {
1735        if window.any_handle == self.window.handle {
1736            let root_view = self
1737                .window
1738                .root_view
1739                .clone()
1740                .unwrap()
1741                .downcast::<T>()
1742                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1743            Ok(read(root_view, self))
1744        } else {
1745            self.app.read_window(window, read)
1746        }
1747    }
1748}
1749
1750impl VisualContext for WindowContext<'_> {
1751    fn new_view<V>(
1752        &mut self,
1753        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1754    ) -> Self::Result<View<V>>
1755    where
1756        V: 'static + Render,
1757    {
1758        let slot = self.app.entities.reserve();
1759        let view = View {
1760            model: slot.clone(),
1761        };
1762        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1763        let entity = build_view_state(&mut cx);
1764        cx.entities.insert(slot, entity);
1765
1766        // Non-generic part to avoid leaking SubscriberSet to invokers of `new_view`.
1767        fn notify_observers(cx: &mut WindowContext, tid: TypeId, view: AnyView) {
1768            cx.new_view_observers.clone().retain(&tid, |observer| {
1769                let any_view = view.clone();
1770                (observer)(any_view, cx);
1771                true
1772            });
1773        }
1774        notify_observers(self, TypeId::of::<V>(), AnyView::from(view.clone()));
1775
1776        view
1777    }
1778
1779    /// Updates the given view. Prefer calling [`View::update`] instead, which calls this method.
1780    fn update_view<T: 'static, R>(
1781        &mut self,
1782        view: &View<T>,
1783        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1784    ) -> Self::Result<R> {
1785        let mut lease = self.app.entities.lease(&view.model);
1786        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, view);
1787        let result = update(&mut *lease, &mut cx);
1788        cx.app.entities.end_lease(lease);
1789        result
1790    }
1791
1792    fn replace_root_view<V>(
1793        &mut self,
1794        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1795    ) -> Self::Result<View<V>>
1796    where
1797        V: 'static + Render,
1798    {
1799        let view = self.new_view(build_view);
1800        self.window.root_view = Some(view.clone().into());
1801        self.refresh();
1802        view
1803    }
1804
1805    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1806        self.update_view(view, |view, cx| {
1807            view.focus_handle(cx).clone().focus(cx);
1808        })
1809    }
1810
1811    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1812    where
1813        V: ManagedView,
1814    {
1815        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1816    }
1817}
1818
1819impl<'a> std::ops::Deref for WindowContext<'a> {
1820    type Target = AppContext;
1821
1822    fn deref(&self) -> &Self::Target {
1823        self.app
1824    }
1825}
1826
1827impl<'a> std::ops::DerefMut for WindowContext<'a> {
1828    fn deref_mut(&mut self) -> &mut Self::Target {
1829        self.app
1830    }
1831}
1832
1833impl<'a> Borrow<AppContext> for WindowContext<'a> {
1834    fn borrow(&self) -> &AppContext {
1835        self.app
1836    }
1837}
1838
1839impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1840    fn borrow_mut(&mut self) -> &mut AppContext {
1841        self.app
1842    }
1843}
1844
1845/// This trait contains functionality that is shared across [`ViewContext`] and [`WindowContext`]
1846pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1847    #[doc(hidden)]
1848    fn app_mut(&mut self) -> &mut AppContext {
1849        self.borrow_mut()
1850    }
1851
1852    #[doc(hidden)]
1853    fn app(&self) -> &AppContext {
1854        self.borrow()
1855    }
1856
1857    #[doc(hidden)]
1858    fn window(&self) -> &Window {
1859        self.borrow()
1860    }
1861
1862    #[doc(hidden)]
1863    fn window_mut(&mut self) -> &mut Window {
1864        self.borrow_mut()
1865    }
1866}
1867
1868impl Borrow<Window> for WindowContext<'_> {
1869    fn borrow(&self) -> &Window {
1870        self.window
1871    }
1872}
1873
1874impl BorrowMut<Window> for WindowContext<'_> {
1875    fn borrow_mut(&mut self) -> &mut Window {
1876        self.window
1877    }
1878}
1879
1880impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
1881
1882/// Provides access to application state that is specialized for a particular [`View`].
1883/// Allows you to interact with focus, emit events, etc.
1884/// ViewContext also derefs to [`WindowContext`], giving you access to all of its methods as well.
1885/// When you call [`View::update`], you're passed a `&mut V` and an `&mut ViewContext<V>`.
1886pub struct ViewContext<'a, V> {
1887    window_cx: WindowContext<'a>,
1888    view: &'a View<V>,
1889}
1890
1891impl<V> Borrow<AppContext> for ViewContext<'_, V> {
1892    fn borrow(&self) -> &AppContext {
1893        &*self.window_cx.app
1894    }
1895}
1896
1897impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
1898    fn borrow_mut(&mut self) -> &mut AppContext {
1899        &mut *self.window_cx.app
1900    }
1901}
1902
1903impl<V> Borrow<Window> for ViewContext<'_, V> {
1904    fn borrow(&self) -> &Window {
1905        &*self.window_cx.window
1906    }
1907}
1908
1909impl<V> BorrowMut<Window> for ViewContext<'_, V> {
1910    fn borrow_mut(&mut self) -> &mut Window {
1911        &mut *self.window_cx.window
1912    }
1913}
1914
1915impl<'a, V: 'static> ViewContext<'a, V> {
1916    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
1917        Self {
1918            window_cx: WindowContext::new(app, window),
1919            view,
1920        }
1921    }
1922
1923    /// Get the entity_id of this view.
1924    pub fn entity_id(&self) -> EntityId {
1925        self.view.entity_id()
1926    }
1927
1928    /// Get the view pointer underlying this context.
1929    pub fn view(&self) -> &View<V> {
1930        self.view
1931    }
1932
1933    /// Get the model underlying this view.
1934    pub fn model(&self) -> &Model<V> {
1935        &self.view.model
1936    }
1937
1938    /// Access the underlying window context.
1939    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
1940        &mut self.window_cx
1941    }
1942
1943    /// Sets a given callback to be run on the next frame.
1944    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
1945    where
1946        V: 'static,
1947    {
1948        let view = self.view().clone();
1949        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
1950    }
1951
1952    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
1953    /// that are currently on the stack to be returned to the app.
1954    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
1955        let view = self.view().downgrade();
1956        self.window_cx.defer(move |cx| {
1957            view.update(cx, f).ok();
1958        });
1959    }
1960
1961    /// Observe another model or view for changes to its state, as tracked by [`ModelContext::notify`].
1962    pub fn observe<V2, E>(
1963        &mut self,
1964        entity: &E,
1965        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
1966    ) -> Subscription
1967    where
1968        V2: 'static,
1969        V: 'static,
1970        E: Entity<V2>,
1971    {
1972        let view = self.view().downgrade();
1973        let entity_id = entity.entity_id();
1974        let entity = entity.downgrade();
1975        let window_handle = self.window.handle;
1976        self.app.new_observer(
1977            entity_id,
1978            Box::new(move |cx| {
1979                window_handle
1980                    .update(cx, |_, cx| {
1981                        if let Some(handle) = E::upgrade_from(&entity) {
1982                            view.update(cx, |this, cx| on_notify(this, handle, cx))
1983                                .is_ok()
1984                        } else {
1985                            false
1986                        }
1987                    })
1988                    .unwrap_or(false)
1989            }),
1990        )
1991    }
1992
1993    /// Subscribe to events emitted by another model or view.
1994    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
1995    /// 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.
1996    pub fn subscribe<V2, E, Evt>(
1997        &mut self,
1998        entity: &E,
1999        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2000    ) -> Subscription
2001    where
2002        V2: EventEmitter<Evt>,
2003        E: Entity<V2>,
2004        Evt: 'static,
2005    {
2006        let view = self.view().downgrade();
2007        let entity_id = entity.entity_id();
2008        let handle = entity.downgrade();
2009        let window_handle = self.window.handle;
2010        self.app.new_subscription(
2011            entity_id,
2012            (
2013                TypeId::of::<Evt>(),
2014                Box::new(move |event, cx| {
2015                    window_handle
2016                        .update(cx, |_, cx| {
2017                            if let Some(handle) = E::upgrade_from(&handle) {
2018                                let event = event.downcast_ref().expect("invalid event type");
2019                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2020                                    .is_ok()
2021                            } else {
2022                                false
2023                            }
2024                        })
2025                        .unwrap_or(false)
2026                }),
2027            ),
2028        )
2029    }
2030
2031    /// Register a callback to be invoked when the view is released.
2032    ///
2033    /// The callback receives a handle to the view's window. This handle may be
2034    /// invalid, if the window was closed before the view was released.
2035    pub fn on_release(
2036        &mut self,
2037        on_release: impl FnOnce(&mut V, AnyWindowHandle, &mut AppContext) + 'static,
2038    ) -> Subscription {
2039        let window_handle = self.window.handle;
2040        let (subscription, activate) = self.app.release_listeners.insert(
2041            self.view.model.entity_id,
2042            Box::new(move |this, cx| {
2043                let this = this.downcast_mut().expect("invalid entity type");
2044                on_release(this, window_handle, cx)
2045            }),
2046        );
2047        activate();
2048        subscription
2049    }
2050
2051    /// Register a callback to be invoked when the given Model or View is released.
2052    pub fn observe_release<V2, E>(
2053        &mut self,
2054        entity: &E,
2055        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2056    ) -> Subscription
2057    where
2058        V: 'static,
2059        V2: 'static,
2060        E: Entity<V2>,
2061    {
2062        let view = self.view().downgrade();
2063        let entity_id = entity.entity_id();
2064        let window_handle = self.window.handle;
2065        let (subscription, activate) = self.app.release_listeners.insert(
2066            entity_id,
2067            Box::new(move |entity, cx| {
2068                let entity = entity.downcast_mut().expect("invalid entity type");
2069                let _ = window_handle.update(cx, |_, cx| {
2070                    view.update(cx, |this, cx| on_release(this, entity, cx))
2071                });
2072            }),
2073        );
2074        activate();
2075        subscription
2076    }
2077
2078    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
2079    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
2080    pub fn notify(&mut self) {
2081        for view_id in self
2082            .window
2083            .rendered_frame
2084            .dispatch_tree
2085            .view_path(self.view.entity_id())
2086            .into_iter()
2087            .rev()
2088        {
2089            if !self.window.dirty_views.insert(view_id) {
2090                break;
2091            }
2092        }
2093
2094        if !self.window.drawing {
2095            self.window_cx.window.dirty.set(true);
2096            self.window_cx.app.push_effect(Effect::Notify {
2097                emitter: self.view.model.entity_id,
2098            });
2099        }
2100    }
2101
2102    /// Register a callback to be invoked when the window is resized.
2103    pub fn observe_window_bounds(
2104        &mut self,
2105        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2106    ) -> Subscription {
2107        let view = self.view.downgrade();
2108        let (subscription, activate) = self.window.bounds_observers.insert(
2109            (),
2110            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2111        );
2112        activate();
2113        subscription
2114    }
2115
2116    /// Register a callback to be invoked when the window is activated or deactivated.
2117    pub fn observe_window_activation(
2118        &mut self,
2119        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2120    ) -> Subscription {
2121        let view = self.view.downgrade();
2122        let (subscription, activate) = self.window.activation_observers.insert(
2123            (),
2124            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2125        );
2126        activate();
2127        subscription
2128    }
2129
2130    /// Registers a callback to be invoked when the window appearance changes.
2131    pub fn observe_window_appearance(
2132        &mut self,
2133        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2134    ) -> Subscription {
2135        let view = self.view.downgrade();
2136        let (subscription, activate) = self.window.appearance_observers.insert(
2137            (),
2138            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2139        );
2140        activate();
2141        subscription
2142    }
2143
2144    /// Register a listener to be called when the given focus handle receives focus.
2145    /// Returns a subscription and persists until the subscription is dropped.
2146    pub fn on_focus(
2147        &mut self,
2148        handle: &FocusHandle,
2149        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2150    ) -> Subscription {
2151        let view = self.view.downgrade();
2152        let focus_id = handle.id;
2153        let (subscription, activate) =
2154            self.window.new_focus_listener(Box::new(move |event, cx| {
2155                view.update(cx, |view, cx| {
2156                    if event.previous_focus_path.last() != Some(&focus_id)
2157                        && event.current_focus_path.last() == Some(&focus_id)
2158                    {
2159                        listener(view, cx)
2160                    }
2161                })
2162                .is_ok()
2163            }));
2164        self.app.defer(|_| activate());
2165        subscription
2166    }
2167
2168    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2169    /// Returns a subscription and persists until the subscription is dropped.
2170    pub fn on_focus_in(
2171        &mut self,
2172        handle: &FocusHandle,
2173        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2174    ) -> Subscription {
2175        let view = self.view.downgrade();
2176        let focus_id = handle.id;
2177        let (subscription, activate) =
2178            self.window.new_focus_listener(Box::new(move |event, cx| {
2179                view.update(cx, |view, cx| {
2180                    if !event.previous_focus_path.contains(&focus_id)
2181                        && event.current_focus_path.contains(&focus_id)
2182                    {
2183                        listener(view, cx)
2184                    }
2185                })
2186                .is_ok()
2187            }));
2188        self.app.defer(move |_| activate());
2189        subscription
2190    }
2191
2192    /// Register a listener to be called when the given focus handle loses focus.
2193    /// Returns a subscription and persists until the subscription is dropped.
2194    pub fn on_blur(
2195        &mut self,
2196        handle: &FocusHandle,
2197        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2198    ) -> Subscription {
2199        let view = self.view.downgrade();
2200        let focus_id = handle.id;
2201        let (subscription, activate) =
2202            self.window.new_focus_listener(Box::new(move |event, cx| {
2203                view.update(cx, |view, cx| {
2204                    if event.previous_focus_path.last() == Some(&focus_id)
2205                        && event.current_focus_path.last() != Some(&focus_id)
2206                    {
2207                        listener(view, cx)
2208                    }
2209                })
2210                .is_ok()
2211            }));
2212        self.app.defer(move |_| activate());
2213        subscription
2214    }
2215
2216    /// Register a listener to be called when nothing in the window has focus.
2217    /// This typically happens when the node that was focused is removed from the tree,
2218    /// and this callback lets you chose a default place to restore the users focus.
2219    /// Returns a subscription and persists until the subscription is dropped.
2220    pub fn on_focus_lost(
2221        &mut self,
2222        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2223    ) -> Subscription {
2224        let view = self.view.downgrade();
2225        let (subscription, activate) = self.window.focus_lost_listeners.insert(
2226            (),
2227            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2228        );
2229        activate();
2230        subscription
2231    }
2232
2233    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2234    /// Returns a subscription and persists until the subscription is dropped.
2235    pub fn on_focus_out(
2236        &mut self,
2237        handle: &FocusHandle,
2238        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2239    ) -> Subscription {
2240        let view = self.view.downgrade();
2241        let focus_id = handle.id;
2242        let (subscription, activate) =
2243            self.window.new_focus_listener(Box::new(move |event, cx| {
2244                view.update(cx, |view, cx| {
2245                    if event.previous_focus_path.contains(&focus_id)
2246                        && !event.current_focus_path.contains(&focus_id)
2247                    {
2248                        listener(view, cx)
2249                    }
2250                })
2251                .is_ok()
2252            }));
2253        self.app.defer(move |_| activate());
2254        subscription
2255    }
2256
2257    /// Schedule a future to be run asynchronously.
2258    /// The given callback is invoked with a [`WeakView<V>`] to avoid leaking the view for a long-running process.
2259    /// It's also given an [`AsyncWindowContext`], which can be used to access the state of the view across await points.
2260    /// The returned future will be polled on the main thread.
2261    pub fn spawn<Fut, R>(
2262        &mut self,
2263        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2264    ) -> Task<R>
2265    where
2266        R: 'static,
2267        Fut: Future<Output = R> + 'static,
2268    {
2269        let view = self.view().downgrade();
2270        self.window_cx.spawn(|cx| f(view, cx))
2271    }
2272
2273    /// Updates the global state of the given type.
2274    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2275    where
2276        G: Global,
2277    {
2278        let mut global = self.app.lease_global::<G>();
2279        let result = f(&mut global, self);
2280        self.app.end_global_lease(global);
2281        result
2282    }
2283
2284    /// Register a callback to be invoked when the given global state changes.
2285    pub fn observe_global<G: Global>(
2286        &mut self,
2287        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2288    ) -> Subscription {
2289        let window_handle = self.window.handle;
2290        let view = self.view().downgrade();
2291        let (subscription, activate) = self.global_observers.insert(
2292            TypeId::of::<G>(),
2293            Box::new(move |cx| {
2294                window_handle
2295                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2296                    .unwrap_or(false)
2297            }),
2298        );
2299        self.app.defer(move |_| activate());
2300        subscription
2301    }
2302
2303    /// Register a callback to be invoked when the given Action type is dispatched to the window.
2304    pub fn on_action(
2305        &mut self,
2306        action_type: TypeId,
2307        listener: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2308    ) {
2309        let handle = self.view().clone();
2310        self.window_cx
2311            .on_action(action_type, move |action, phase, cx| {
2312                handle.update(cx, |view, cx| {
2313                    listener(view, action, phase, cx);
2314                })
2315            });
2316    }
2317
2318    /// Emit an event to be handled any other views that have subscribed via [ViewContext::subscribe].
2319    pub fn emit<Evt>(&mut self, event: Evt)
2320    where
2321        Evt: 'static,
2322        V: EventEmitter<Evt>,
2323    {
2324        let emitter = self.view.model.entity_id;
2325        self.app.push_effect(Effect::Emit {
2326            emitter,
2327            event_type: TypeId::of::<Evt>(),
2328            event: Box::new(event),
2329        });
2330    }
2331
2332    /// Move focus to the current view, assuming it implements [`FocusableView`].
2333    pub fn focus_self(&mut self)
2334    where
2335        V: FocusableView,
2336    {
2337        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2338    }
2339
2340    /// Convenience method for accessing view state in an event callback.
2341    ///
2342    /// Many GPUI callbacks take the form of `Fn(&E, &mut WindowContext)`,
2343    /// but it's often useful to be able to access view state in these
2344    /// callbacks. This method provides a convenient way to do so.
2345    pub fn listener<E>(
2346        &self,
2347        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2348    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2349        let view = self.view().downgrade();
2350        move |e: &E, cx: &mut WindowContext| {
2351            view.update(cx, |view, cx| f(view, e, cx)).ok();
2352        }
2353    }
2354}
2355
2356impl<V> Context for ViewContext<'_, V> {
2357    type Result<U> = U;
2358
2359    fn new_model<T: 'static>(
2360        &mut self,
2361        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2362    ) -> Model<T> {
2363        self.window_cx.new_model(build_model)
2364    }
2365
2366    fn update_model<T: 'static, R>(
2367        &mut self,
2368        model: &Model<T>,
2369        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2370    ) -> R {
2371        self.window_cx.update_model(model, update)
2372    }
2373
2374    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2375    where
2376        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2377    {
2378        self.window_cx.update_window(window, update)
2379    }
2380
2381    fn read_model<T, R>(
2382        &self,
2383        handle: &Model<T>,
2384        read: impl FnOnce(&T, &AppContext) -> R,
2385    ) -> Self::Result<R>
2386    where
2387        T: 'static,
2388    {
2389        self.window_cx.read_model(handle, read)
2390    }
2391
2392    fn read_window<T, R>(
2393        &self,
2394        window: &WindowHandle<T>,
2395        read: impl FnOnce(View<T>, &AppContext) -> R,
2396    ) -> Result<R>
2397    where
2398        T: 'static,
2399    {
2400        self.window_cx.read_window(window, read)
2401    }
2402}
2403
2404impl<V: 'static> VisualContext for ViewContext<'_, V> {
2405    fn new_view<W: Render + 'static>(
2406        &mut self,
2407        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2408    ) -> Self::Result<View<W>> {
2409        self.window_cx.new_view(build_view_state)
2410    }
2411
2412    fn update_view<V2: 'static, R>(
2413        &mut self,
2414        view: &View<V2>,
2415        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2416    ) -> Self::Result<R> {
2417        self.window_cx.update_view(view, update)
2418    }
2419
2420    fn replace_root_view<W>(
2421        &mut self,
2422        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2423    ) -> Self::Result<View<W>>
2424    where
2425        W: 'static + Render,
2426    {
2427        self.window_cx.replace_root_view(build_view)
2428    }
2429
2430    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2431        self.window_cx.focus_view(view)
2432    }
2433
2434    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2435        self.window_cx.dismiss_view(view)
2436    }
2437}
2438
2439impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2440    type Target = WindowContext<'a>;
2441
2442    fn deref(&self) -> &Self::Target {
2443        &self.window_cx
2444    }
2445}
2446
2447impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2448    fn deref_mut(&mut self) -> &mut Self::Target {
2449        &mut self.window_cx
2450    }
2451}
2452
2453// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2454slotmap::new_key_type! {
2455    /// A unique identifier for a window.
2456    pub struct WindowId;
2457}
2458
2459impl WindowId {
2460    /// Converts this window ID to a `u64`.
2461    pub fn as_u64(&self) -> u64 {
2462        self.0.as_ffi()
2463    }
2464}
2465
2466/// A handle to a window with a specific root view type.
2467/// Note that this does not keep the window alive on its own.
2468#[derive(Deref, DerefMut)]
2469pub struct WindowHandle<V> {
2470    #[deref]
2471    #[deref_mut]
2472    pub(crate) any_handle: AnyWindowHandle,
2473    state_type: PhantomData<V>,
2474}
2475
2476impl<V: 'static + Render> WindowHandle<V> {
2477    /// Creates a new handle from a window ID.
2478    /// This does not check if the root type of the window is `V`.
2479    pub fn new(id: WindowId) -> Self {
2480        WindowHandle {
2481            any_handle: AnyWindowHandle {
2482                id,
2483                state_type: TypeId::of::<V>(),
2484            },
2485            state_type: PhantomData,
2486        }
2487    }
2488
2489    /// Get the root view out of this window.
2490    ///
2491    /// This will fail if the window is closed or if the root view's type does not match `V`.
2492    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2493    where
2494        C: Context,
2495    {
2496        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2497            root_view
2498                .downcast::<V>()
2499                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2500        }))
2501    }
2502
2503    /// Updates the root view of this window.
2504    ///
2505    /// This will fail if the window has been closed or if the root view's type does not match
2506    pub fn update<C, R>(
2507        &self,
2508        cx: &mut C,
2509        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2510    ) -> Result<R>
2511    where
2512        C: Context,
2513    {
2514        cx.update_window(self.any_handle, |root_view, cx| {
2515            let view = root_view
2516                .downcast::<V>()
2517                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2518            Ok(cx.update_view(&view, update))
2519        })?
2520    }
2521
2522    /// Read the root view out of this window.
2523    ///
2524    /// This will fail if the window is closed or if the root view's type does not match `V`.
2525    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2526        let x = cx
2527            .windows
2528            .get(self.id)
2529            .and_then(|window| {
2530                window
2531                    .as_ref()
2532                    .and_then(|window| window.root_view.clone())
2533                    .map(|root_view| root_view.downcast::<V>())
2534            })
2535            .ok_or_else(|| anyhow!("window not found"))?
2536            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2537
2538        Ok(x.read(cx))
2539    }
2540
2541    /// Read the root view out of this window, with a callback
2542    ///
2543    /// This will fail if the window is closed or if the root view's type does not match `V`.
2544    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2545    where
2546        C: Context,
2547    {
2548        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2549    }
2550
2551    /// Read the root view pointer off of this window.
2552    ///
2553    /// This will fail if the window is closed or if the root view's type does not match `V`.
2554    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2555    where
2556        C: Context,
2557    {
2558        cx.read_window(self, |root_view, _cx| root_view.clone())
2559    }
2560
2561    /// Check if this window is 'active'.
2562    ///
2563    /// Will return `None` if the window is closed or currently
2564    /// borrowed.
2565    pub fn is_active(&self, cx: &mut AppContext) -> Option<bool> {
2566        cx.update_window(self.any_handle, |_, cx| cx.is_window_active())
2567            .ok()
2568    }
2569}
2570
2571impl<V> Copy for WindowHandle<V> {}
2572
2573impl<V> Clone for WindowHandle<V> {
2574    fn clone(&self) -> Self {
2575        *self
2576    }
2577}
2578
2579impl<V> PartialEq for WindowHandle<V> {
2580    fn eq(&self, other: &Self) -> bool {
2581        self.any_handle == other.any_handle
2582    }
2583}
2584
2585impl<V> Eq for WindowHandle<V> {}
2586
2587impl<V> Hash for WindowHandle<V> {
2588    fn hash<H: Hasher>(&self, state: &mut H) {
2589        self.any_handle.hash(state);
2590    }
2591}
2592
2593impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle {
2594    fn from(val: WindowHandle<V>) -> Self {
2595        val.any_handle
2596    }
2597}
2598
2599/// A handle to a window with any root view type, which can be downcast to a window with a specific root view type.
2600#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2601pub struct AnyWindowHandle {
2602    pub(crate) id: WindowId,
2603    state_type: TypeId,
2604}
2605
2606impl AnyWindowHandle {
2607    /// Get the ID of this window.
2608    pub fn window_id(&self) -> WindowId {
2609        self.id
2610    }
2611
2612    /// Attempt to convert this handle to a window handle with a specific root view type.
2613    /// If the types do not match, this will return `None`.
2614    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2615        if TypeId::of::<T>() == self.state_type {
2616            Some(WindowHandle {
2617                any_handle: *self,
2618                state_type: PhantomData,
2619            })
2620        } else {
2621            None
2622        }
2623    }
2624
2625    /// Updates the state of the root view of this window.
2626    ///
2627    /// This will fail if the window has been closed.
2628    pub fn update<C, R>(
2629        self,
2630        cx: &mut C,
2631        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2632    ) -> Result<R>
2633    where
2634        C: Context,
2635    {
2636        cx.update_window(self, update)
2637    }
2638
2639    /// Read the state of the root view of this window.
2640    ///
2641    /// This will fail if the window has been closed.
2642    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2643    where
2644        C: Context,
2645        T: 'static,
2646    {
2647        let view = self
2648            .downcast::<T>()
2649            .context("the type of the window's root view has changed")?;
2650
2651        cx.read_window(&view, read)
2652    }
2653}
2654
2655/// An identifier for an [`Element`](crate::Element).
2656///
2657/// Can be constructed with a string, a number, or both, as well
2658/// as other internal representations.
2659#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2660pub enum ElementId {
2661    /// The ID of a View element
2662    View(EntityId),
2663    /// An integer ID.
2664    Integer(usize),
2665    /// A string based ID.
2666    Name(SharedString),
2667    /// An ID that's equated with a focus handle.
2668    FocusHandle(FocusId),
2669    /// A combination of a name and an integer.
2670    NamedInteger(SharedString, usize),
2671}
2672
2673impl Display for ElementId {
2674    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
2675        match self {
2676            ElementId::View(entity_id) => write!(f, "view-{}", entity_id)?,
2677            ElementId::Integer(ix) => write!(f, "{}", ix)?,
2678            ElementId::Name(name) => write!(f, "{}", name)?,
2679            ElementId::FocusHandle(_) => write!(f, "FocusHandle")?,
2680            ElementId::NamedInteger(s, i) => write!(f, "{}-{}", s, i)?,
2681        }
2682
2683        Ok(())
2684    }
2685}
2686
2687impl ElementId {
2688    pub(crate) fn from_entity_id(entity_id: EntityId) -> Self {
2689        ElementId::View(entity_id)
2690    }
2691}
2692
2693impl TryInto<SharedString> for ElementId {
2694    type Error = anyhow::Error;
2695
2696    fn try_into(self) -> anyhow::Result<SharedString> {
2697        if let ElementId::Name(name) = self {
2698            Ok(name)
2699        } else {
2700            Err(anyhow!("element id is not string"))
2701        }
2702    }
2703}
2704
2705impl From<usize> for ElementId {
2706    fn from(id: usize) -> Self {
2707        ElementId::Integer(id)
2708    }
2709}
2710
2711impl From<i32> for ElementId {
2712    fn from(id: i32) -> Self {
2713        Self::Integer(id as usize)
2714    }
2715}
2716
2717impl From<SharedString> for ElementId {
2718    fn from(name: SharedString) -> Self {
2719        ElementId::Name(name)
2720    }
2721}
2722
2723impl From<&'static str> for ElementId {
2724    fn from(name: &'static str) -> Self {
2725        ElementId::Name(name.into())
2726    }
2727}
2728
2729impl<'a> From<&'a FocusHandle> for ElementId {
2730    fn from(handle: &'a FocusHandle) -> Self {
2731        ElementId::FocusHandle(handle.id)
2732    }
2733}
2734
2735impl From<(&'static str, EntityId)> for ElementId {
2736    fn from((name, id): (&'static str, EntityId)) -> Self {
2737        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2738    }
2739}
2740
2741impl From<(&'static str, usize)> for ElementId {
2742    fn from((name, id): (&'static str, usize)) -> Self {
2743        ElementId::NamedInteger(name.into(), id)
2744    }
2745}
2746
2747impl From<(&'static str, u64)> for ElementId {
2748    fn from((name, id): (&'static str, u64)) -> Self {
2749        ElementId::NamedInteger(name.into(), id as usize)
2750    }
2751}
2752
2753/// A rectangle to be rendered in the window at the given position and size.
2754/// Passed as an argument [`ElementContext::paint_quad`].
2755#[derive(Clone)]
2756pub struct PaintQuad {
2757    bounds: Bounds<Pixels>,
2758    corner_radii: Corners<Pixels>,
2759    background: Hsla,
2760    border_widths: Edges<Pixels>,
2761    border_color: Hsla,
2762}
2763
2764impl PaintQuad {
2765    /// Sets the corner radii of the quad.
2766    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
2767        PaintQuad {
2768            corner_radii: corner_radii.into(),
2769            ..self
2770        }
2771    }
2772
2773    /// Sets the border widths of the quad.
2774    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
2775        PaintQuad {
2776            border_widths: border_widths.into(),
2777            ..self
2778        }
2779    }
2780
2781    /// Sets the border color of the quad.
2782    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
2783        PaintQuad {
2784            border_color: border_color.into(),
2785            ..self
2786        }
2787    }
2788
2789    /// Sets the background color of the quad.
2790    pub fn background(self, background: impl Into<Hsla>) -> Self {
2791        PaintQuad {
2792            background: background.into(),
2793            ..self
2794        }
2795    }
2796}
2797
2798/// Creates a quad with the given parameters.
2799pub fn quad(
2800    bounds: Bounds<Pixels>,
2801    corner_radii: impl Into<Corners<Pixels>>,
2802    background: impl Into<Hsla>,
2803    border_widths: impl Into<Edges<Pixels>>,
2804    border_color: impl Into<Hsla>,
2805) -> PaintQuad {
2806    PaintQuad {
2807        bounds,
2808        corner_radii: corner_radii.into(),
2809        background: background.into(),
2810        border_widths: border_widths.into(),
2811        border_color: border_color.into(),
2812    }
2813}
2814
2815/// Creates a filled quad with the given bounds and background color.
2816pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
2817    PaintQuad {
2818        bounds: bounds.into(),
2819        corner_radii: (0.).into(),
2820        background: background.into(),
2821        border_widths: (0.).into(),
2822        border_color: transparent_black(),
2823    }
2824}
2825
2826/// Creates a rectangle outline with the given bounds, border color, and a 1px border width
2827pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
2828    PaintQuad {
2829        bounds: bounds.into(),
2830        corner_radii: (0.).into(),
2831        background: transparent_black(),
2832        border_widths: (1.).into(),
2833        border_color: border_color.into(),
2834    }
2835}