window.rs

   1use crate::{
   2    px, size, transparent_black, Action, AnyDrag, AnyView, AppContext, Arena, AsyncWindowContext,
   3    AvailableSpace, Bounds, Context, Corners, CursorStyle, DispatchActionListener, DispatchNodeId,
   4    DispatchTree, DisplayId, Edges, Effect, Entity, EntityId, EventEmitter, FileDropEvent, Flatten,
   5    Global, GlobalElementId, Hsla, KeyBinding, KeyContext, KeyDownEvent, KeyMatch, KeymatchResult,
   6    Keystroke, KeystrokeEvent, Model, ModelContext, Modifiers, MouseButton, MouseMoveEvent,
   7    MouseUpEvent, Pixels, PlatformAtlas, PlatformDisplay, PlatformInput, PlatformWindow, Point,
   8    PromptLevel, Render, ScaledPixels, SharedString, Size, SubscriberSet, Subscription,
   9    TaffyLayoutEngine, Task, View, VisualContext, WeakView, WindowAppearance, WindowBounds,
  10    WindowOptions, WindowTextSystem,
  11};
  12use anyhow::{anyhow, Context as _, Result};
  13use collections::FxHashSet;
  14use derive_more::{Deref, DerefMut};
  15use futures::channel::oneshot;
  16use parking_lot::RwLock;
  17use slotmap::SlotMap;
  18use smallvec::SmallVec;
  19use std::{
  20    any::{Any, TypeId},
  21    borrow::{Borrow, BorrowMut},
  22    cell::{Cell, RefCell},
  23    fmt::{Debug, Display},
  24    future::Future,
  25    hash::{Hash, Hasher},
  26    marker::PhantomData,
  27    mem,
  28    rc::Rc,
  29    sync::{
  30        atomic::{AtomicUsize, Ordering::SeqCst},
  31        Arc,
  32    },
  33    time::{Duration, Instant},
  34};
  35use util::{measure, ResultExt};
  36
  37mod element_cx;
  38pub use element_cx::*;
  39
  40const ACTIVE_DRAG_Z_INDEX: u16 = 1;
  41
  42/// A global stacking order, which is created by stacking successive z-index values.
  43/// Each z-index will always be interpreted in the context of its parent z-index.
  44#[derive(Debug, Deref, DerefMut, Clone, Ord, PartialOrd, PartialEq, Eq, Default)]
  45pub struct StackingOrder(SmallVec<[StackingContext; 64]>);
  46
  47/// A single entry in a primitive's z-index stacking order
  48#[derive(Clone, Ord, PartialOrd, PartialEq, Eq, Default)]
  49pub struct StackingContext {
  50    pub(crate) z_index: u16,
  51    pub(crate) id: u16,
  52}
  53
  54impl std::fmt::Debug for StackingContext {
  55    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  56        write!(f, "{{{}.{}}} ", self.z_index, self.id)
  57    }
  58}
  59
  60/// Represents the two different phases when dispatching events.
  61#[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
  62pub enum DispatchPhase {
  63    /// After the capture phase comes the bubble phase, in which mouse event listeners are
  64    /// invoked front to back and keyboard event listeners are invoked from the focused element
  65    /// to the root of the element tree. This is the phase you'll most commonly want to use when
  66    /// registering event listeners.
  67    #[default]
  68    Bubble,
  69    /// During the initial capture phase, mouse event listeners are invoked back to front, and keyboard
  70    /// listeners are invoked from the root of the tree downward toward the focused element. This phase
  71    /// is used for special purposes such as clearing the "pressed" state for click events. If
  72    /// you stop event propagation during this phase, you need to know what you're doing. Handlers
  73    /// outside of the immediate region may rely on detecting non-local events during this phase.
  74    Capture,
  75}
  76
  77impl DispatchPhase {
  78    /// Returns true if this represents the "bubble" phase.
  79    pub fn bubble(self) -> bool {
  80        self == DispatchPhase::Bubble
  81    }
  82
  83    /// Returns true if this represents the "capture" phase.
  84    pub fn capture(self) -> bool {
  85        self == DispatchPhase::Capture
  86    }
  87}
  88
  89type AnyObserver = Box<dyn FnMut(&mut WindowContext) -> bool + 'static>;
  90
  91type AnyWindowFocusListener = Box<dyn FnMut(&FocusEvent, &mut WindowContext) -> bool + 'static>;
  92
  93struct FocusEvent {
  94    previous_focus_path: SmallVec<[FocusId; 8]>,
  95    current_focus_path: SmallVec<[FocusId; 8]>,
  96}
  97
  98slotmap::new_key_type! {
  99    /// A globally unique identifier for a focusable element.
 100    pub struct FocusId;
 101}
 102
 103thread_local! {
 104    pub(crate) static ELEMENT_ARENA: RefCell<Arena> = RefCell::new(Arena::new(8 * 1024 * 1024));
 105}
 106
 107impl FocusId {
 108    /// Obtains whether the element associated with this handle is currently focused.
 109    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 110        cx.window.focus == Some(*self)
 111    }
 112
 113    /// Obtains whether the element associated with this handle contains the focused
 114    /// element or is itself focused.
 115    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 116        cx.focused()
 117            .map_or(false, |focused| self.contains(focused.id, cx))
 118    }
 119
 120    /// Obtains whether the element associated with this handle is contained within the
 121    /// focused element or is itself focused.
 122    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 123        let focused = cx.focused();
 124        focused.map_or(false, |focused| focused.id.contains(*self, cx))
 125    }
 126
 127    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 128    pub(crate) fn contains(&self, other: Self, cx: &WindowContext) -> bool {
 129        cx.window
 130            .rendered_frame
 131            .dispatch_tree
 132            .focus_contains(*self, other)
 133    }
 134}
 135
 136/// A handle which can be used to track and manipulate the focused element in a window.
 137pub struct FocusHandle {
 138    pub(crate) id: FocusId,
 139    handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 140}
 141
 142impl std::fmt::Debug for FocusHandle {
 143    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
 144        f.write_fmt(format_args!("FocusHandle({:?})", self.id))
 145    }
 146}
 147
 148impl FocusHandle {
 149    pub(crate) fn new(handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>) -> Self {
 150        let id = handles.write().insert(AtomicUsize::new(1));
 151        Self {
 152            id,
 153            handles: handles.clone(),
 154        }
 155    }
 156
 157    pub(crate) fn for_id(
 158        id: FocusId,
 159        handles: &Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 160    ) -> Option<Self> {
 161        let lock = handles.read();
 162        let ref_count = lock.get(id)?;
 163        if ref_count.load(SeqCst) == 0 {
 164            None
 165        } else {
 166            ref_count.fetch_add(1, SeqCst);
 167            Some(Self {
 168                id,
 169                handles: handles.clone(),
 170            })
 171        }
 172    }
 173
 174    /// Moves the focus to the element associated with this handle.
 175    pub fn focus(&self, cx: &mut WindowContext) {
 176        cx.focus(self)
 177    }
 178
 179    /// Obtains whether the element associated with this handle is currently focused.
 180    pub fn is_focused(&self, cx: &WindowContext) -> bool {
 181        self.id.is_focused(cx)
 182    }
 183
 184    /// Obtains whether the element associated with this handle contains the focused
 185    /// element or is itself focused.
 186    pub fn contains_focused(&self, cx: &WindowContext) -> bool {
 187        self.id.contains_focused(cx)
 188    }
 189
 190    /// Obtains whether the element associated with this handle is contained within the
 191    /// focused element or is itself focused.
 192    pub fn within_focused(&self, cx: &WindowContext) -> bool {
 193        self.id.within_focused(cx)
 194    }
 195
 196    /// Obtains whether this handle contains the given handle in the most recently rendered frame.
 197    pub fn contains(&self, other: &Self, cx: &WindowContext) -> bool {
 198        self.id.contains(other.id, cx)
 199    }
 200}
 201
 202impl Clone for FocusHandle {
 203    fn clone(&self) -> Self {
 204        Self::for_id(self.id, &self.handles).unwrap()
 205    }
 206}
 207
 208impl PartialEq for FocusHandle {
 209    fn eq(&self, other: &Self) -> bool {
 210        self.id == other.id
 211    }
 212}
 213
 214impl Eq for FocusHandle {}
 215
 216impl Drop for FocusHandle {
 217    fn drop(&mut self) {
 218        self.handles
 219            .read()
 220            .get(self.id)
 221            .unwrap()
 222            .fetch_sub(1, SeqCst);
 223    }
 224}
 225
 226/// FocusableView allows users of your view to easily
 227/// focus it (using cx.focus_view(view))
 228pub trait FocusableView: 'static + Render {
 229    /// Returns the focus handle associated with this view.
 230    fn focus_handle(&self, cx: &AppContext) -> FocusHandle;
 231}
 232
 233/// ManagedView is a view (like a Modal, Popover, Menu, etc.)
 234/// where the lifecycle of the view is handled by another view.
 235pub trait ManagedView: FocusableView + EventEmitter<DismissEvent> {}
 236
 237impl<M: FocusableView + EventEmitter<DismissEvent>> ManagedView for M {}
 238
 239/// Emitted by implementers of [`ManagedView`] to indicate the view should be dismissed, such as when a view is presented as a modal.
 240pub struct DismissEvent;
 241
 242type FrameCallback = Box<dyn FnOnce(&mut WindowContext)>;
 243
 244// Holds the state for a specific window.
 245#[doc(hidden)]
 246pub struct Window {
 247    pub(crate) handle: AnyWindowHandle,
 248    pub(crate) removed: bool,
 249    pub(crate) platform_window: Box<dyn PlatformWindow>,
 250    display_id: DisplayId,
 251    sprite_atlas: Arc<dyn PlatformAtlas>,
 252    text_system: Arc<WindowTextSystem>,
 253    pub(crate) rem_size: Pixels,
 254    pub(crate) viewport_size: Size<Pixels>,
 255    layout_engine: Option<TaffyLayoutEngine>,
 256    pub(crate) root_view: Option<AnyView>,
 257    pub(crate) element_id_stack: GlobalElementId,
 258    pub(crate) rendered_frame: Frame,
 259    pub(crate) next_frame: Frame,
 260    next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>>,
 261    pub(crate) dirty_views: FxHashSet<EntityId>,
 262    pub(crate) focus_handles: Arc<RwLock<SlotMap<FocusId, AtomicUsize>>>,
 263    focus_listeners: SubscriberSet<(), AnyWindowFocusListener>,
 264    focus_lost_listeners: SubscriberSet<(), AnyObserver>,
 265    default_prevented: bool,
 266    mouse_position: Point<Pixels>,
 267    modifiers: Modifiers,
 268    scale_factor: f32,
 269    bounds: WindowBounds,
 270    bounds_observers: SubscriberSet<(), AnyObserver>,
 271    appearance: WindowAppearance,
 272    appearance_observers: SubscriberSet<(), AnyObserver>,
 273    active: Rc<Cell<bool>>,
 274    pub(crate) dirty: Rc<Cell<bool>>,
 275    pub(crate) needs_present: Rc<Cell<bool>>,
 276    pub(crate) last_input_timestamp: Rc<Cell<Instant>>,
 277    pub(crate) refreshing: bool,
 278    pub(crate) drawing: bool,
 279    activation_observers: SubscriberSet<(), AnyObserver>,
 280    pub(crate) focus: Option<FocusId>,
 281    focus_enabled: bool,
 282    pending_input: Option<PendingInput>,
 283    graphics_profiler_enabled: bool,
 284}
 285
 286#[derive(Default, Debug)]
 287struct PendingInput {
 288    keystrokes: SmallVec<[Keystroke; 1]>,
 289    bindings: SmallVec<[KeyBinding; 1]>,
 290    focus: Option<FocusId>,
 291    timer: Option<Task<()>>,
 292}
 293
 294impl PendingInput {
 295    fn input(&self) -> String {
 296        self.keystrokes
 297            .iter()
 298            .flat_map(|k| k.ime_key.clone())
 299            .collect::<Vec<String>>()
 300            .join("")
 301    }
 302
 303    fn used_by_binding(&self, binding: &KeyBinding) -> bool {
 304        if self.keystrokes.is_empty() {
 305            return true;
 306        }
 307        let keystroke = &self.keystrokes[0];
 308        for candidate in keystroke.match_candidates() {
 309            if binding.match_keystrokes(&[candidate]) == KeyMatch::Pending {
 310                return true;
 311            }
 312        }
 313        false
 314    }
 315}
 316
 317pub(crate) struct ElementStateBox {
 318    pub(crate) inner: Box<dyn Any>,
 319    pub(crate) parent_view_id: EntityId,
 320    #[cfg(debug_assertions)]
 321    pub(crate) type_name: &'static str,
 322}
 323
 324impl Window {
 325    pub(crate) fn new(
 326        handle: AnyWindowHandle,
 327        options: WindowOptions,
 328        cx: &mut AppContext,
 329    ) -> Self {
 330        let platform_window = cx.platform.open_window(handle, options);
 331        let display_id = platform_window.display().id();
 332        let sprite_atlas = platform_window.sprite_atlas();
 333        let mouse_position = platform_window.mouse_position();
 334        let modifiers = platform_window.modifiers();
 335        let content_size = platform_window.content_size();
 336        let scale_factor = platform_window.scale_factor();
 337        let bounds = platform_window.bounds();
 338        let appearance = platform_window.appearance();
 339        let text_system = Arc::new(WindowTextSystem::new(cx.text_system().clone()));
 340        let dirty = Rc::new(Cell::new(true));
 341        let active = Rc::new(Cell::new(false));
 342        let needs_present = Rc::new(Cell::new(false));
 343        let next_frame_callbacks: Rc<RefCell<Vec<FrameCallback>>> = Default::default();
 344        let last_input_timestamp = Rc::new(Cell::new(Instant::now()));
 345
 346        platform_window.on_close(Box::new({
 347            let mut cx = cx.to_async();
 348            move || {
 349                let _ = handle.update(&mut cx, |_, cx| cx.remove_window());
 350            }
 351        }));
 352        platform_window.on_request_frame(Box::new({
 353            let mut cx = cx.to_async();
 354            let dirty = dirty.clone();
 355            let active = active.clone();
 356            let needs_present = needs_present.clone();
 357            let next_frame_callbacks = next_frame_callbacks.clone();
 358            let last_input_timestamp = last_input_timestamp.clone();
 359            move || {
 360                let next_frame_callbacks = next_frame_callbacks.take();
 361                if !next_frame_callbacks.is_empty() {
 362                    handle
 363                        .update(&mut cx, |_, cx| {
 364                            for callback in next_frame_callbacks {
 365                                callback(cx);
 366                            }
 367                        })
 368                        .log_err();
 369                }
 370
 371                // Keep presenting the current scene for 1 extra second since the
 372                // last input to prevent the display from underclocking the refresh rate.
 373                let needs_present = needs_present.get()
 374                    || (active.get()
 375                        && last_input_timestamp.get().elapsed() < Duration::from_secs(1));
 376
 377                if dirty.get() {
 378                    measure("frame duration", || {
 379                        handle
 380                            .update(&mut cx, |_, cx| {
 381                                cx.draw();
 382                                cx.present();
 383                            })
 384                            .log_err();
 385                    })
 386                } else if needs_present {
 387                    handle.update(&mut cx, |_, cx| cx.present()).log_err();
 388                }
 389            }
 390        }));
 391        platform_window.on_resize(Box::new({
 392            let mut cx = cx.to_async();
 393            move |_, _| {
 394                handle
 395                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 396                    .log_err();
 397            }
 398        }));
 399        platform_window.on_moved(Box::new({
 400            let mut cx = cx.to_async();
 401            move || {
 402                handle
 403                    .update(&mut cx, |_, cx| cx.window_bounds_changed())
 404                    .log_err();
 405            }
 406        }));
 407        platform_window.on_appearance_changed(Box::new({
 408            let mut cx = cx.to_async();
 409            move || {
 410                handle
 411                    .update(&mut cx, |_, cx| cx.appearance_changed())
 412                    .log_err();
 413            }
 414        }));
 415        platform_window.on_active_status_change(Box::new({
 416            let mut cx = cx.to_async();
 417            move |active| {
 418                handle
 419                    .update(&mut cx, |_, cx| {
 420                        cx.window.active.set(active);
 421                        cx.window
 422                            .activation_observers
 423                            .clone()
 424                            .retain(&(), |callback| callback(cx));
 425                    })
 426                    .log_err();
 427            }
 428        }));
 429
 430        platform_window.on_input({
 431            let mut cx = cx.to_async();
 432            Box::new(move |event| {
 433                handle
 434                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
 435                    .log_err()
 436                    .unwrap_or(false)
 437            })
 438        });
 439
 440        Window {
 441            handle,
 442            removed: false,
 443            platform_window,
 444            display_id,
 445            sprite_atlas,
 446            text_system,
 447            rem_size: px(16.),
 448            viewport_size: content_size,
 449            layout_engine: Some(TaffyLayoutEngine::new()),
 450            root_view: None,
 451            element_id_stack: GlobalElementId::default(),
 452            rendered_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 453            next_frame: Frame::new(DispatchTree::new(cx.keymap.clone(), cx.actions.clone())),
 454            next_frame_callbacks,
 455            dirty_views: FxHashSet::default(),
 456            focus_handles: Arc::new(RwLock::new(SlotMap::with_key())),
 457            focus_listeners: SubscriberSet::new(),
 458            focus_lost_listeners: SubscriberSet::new(),
 459            default_prevented: true,
 460            mouse_position,
 461            modifiers,
 462            scale_factor,
 463            bounds,
 464            bounds_observers: SubscriberSet::new(),
 465            appearance,
 466            appearance_observers: SubscriberSet::new(),
 467            active,
 468            dirty,
 469            needs_present,
 470            last_input_timestamp,
 471            refreshing: false,
 472            drawing: false,
 473            activation_observers: SubscriberSet::new(),
 474            focus: None,
 475            focus_enabled: true,
 476            pending_input: None,
 477            graphics_profiler_enabled: false,
 478        }
 479    }
 480    fn new_focus_listener(
 481        &mut self,
 482        value: AnyWindowFocusListener,
 483    ) -> (Subscription, impl FnOnce()) {
 484        self.focus_listeners.insert((), value)
 485    }
 486}
 487
 488/// Indicates which region of the window is visible. Content falling outside of this mask will not be
 489/// rendered. Currently, only rectangular content masks are supported, but we give the mask its own type
 490/// to leave room to support more complex shapes in the future.
 491#[derive(Clone, Debug, Default, PartialEq, Eq)]
 492#[repr(C)]
 493pub struct ContentMask<P: Clone + Default + Debug> {
 494    /// The bounds
 495    pub bounds: Bounds<P>,
 496}
 497
 498impl ContentMask<Pixels> {
 499    /// Scale the content mask's pixel units by the given scaling factor.
 500    pub fn scale(&self, factor: f32) -> ContentMask<ScaledPixels> {
 501        ContentMask {
 502            bounds: self.bounds.scale(factor),
 503        }
 504    }
 505
 506    /// Intersect the content mask with the given content mask.
 507    pub fn intersect(&self, other: &Self) -> Self {
 508        let bounds = self.bounds.intersect(&other.bounds);
 509        ContentMask { bounds }
 510    }
 511}
 512
 513/// Provides access to application state in the context of a single window. Derefs
 514/// to an [`AppContext`], so you can also pass a [`WindowContext`] to any method that takes
 515/// an [`AppContext`] and call any [`AppContext`] methods.
 516pub struct WindowContext<'a> {
 517    pub(crate) app: &'a mut AppContext,
 518    pub(crate) window: &'a mut Window,
 519}
 520
 521impl<'a> WindowContext<'a> {
 522    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
 523        Self { app, window }
 524    }
 525
 526    /// Obtain a handle to the window that belongs to this context.
 527    pub fn window_handle(&self) -> AnyWindowHandle {
 528        self.window.handle
 529    }
 530
 531    /// Mark the window as dirty, scheduling it to be redrawn on the next frame.
 532    pub fn refresh(&mut self) {
 533        if !self.window.drawing {
 534            self.window.refreshing = true;
 535            self.window.dirty.set(true);
 536        }
 537    }
 538
 539    /// Close this window.
 540    pub fn remove_window(&mut self) {
 541        self.window.removed = true;
 542    }
 543
 544    /// Obtain a new [`FocusHandle`], which allows you to track and manipulate the keyboard focus
 545    /// for elements rendered within this window.
 546    pub fn focus_handle(&mut self) -> FocusHandle {
 547        FocusHandle::new(&self.window.focus_handles)
 548    }
 549
 550    /// Obtain the currently focused [`FocusHandle`]. If no elements are focused, returns `None`.
 551    pub fn focused(&self) -> Option<FocusHandle> {
 552        self.window
 553            .focus
 554            .and_then(|id| FocusHandle::for_id(id, &self.window.focus_handles))
 555    }
 556
 557    /// Move focus to the element associated with the given [`FocusHandle`].
 558    pub fn focus(&mut self, handle: &FocusHandle) {
 559        if !self.window.focus_enabled || self.window.focus == Some(handle.id) {
 560            return;
 561        }
 562
 563        self.window.focus = Some(handle.id);
 564        self.window
 565            .rendered_frame
 566            .dispatch_tree
 567            .clear_pending_keystrokes();
 568        self.refresh();
 569    }
 570
 571    /// Remove focus from all elements within this context's window.
 572    pub fn blur(&mut self) {
 573        if !self.window.focus_enabled {
 574            return;
 575        }
 576
 577        self.window.focus = None;
 578        self.refresh();
 579    }
 580
 581    /// Blur the window and don't allow anything in it to be focused again.
 582    pub fn disable_focus(&mut self) {
 583        self.blur();
 584        self.window.focus_enabled = false;
 585    }
 586
 587    /// Accessor for the text system.
 588    pub fn text_system(&self) -> &Arc<WindowTextSystem> {
 589        &self.window.text_system
 590    }
 591
 592    /// Dispatch the given action on the currently focused element.
 593    pub fn dispatch_action(&mut self, action: Box<dyn Action>) {
 594        let focus_handle = self.focused();
 595
 596        self.defer(move |cx| {
 597            let node_id = focus_handle
 598                .and_then(|handle| {
 599                    cx.window
 600                        .rendered_frame
 601                        .dispatch_tree
 602                        .focusable_node_id(handle.id)
 603                })
 604                .unwrap_or_else(|| cx.window.rendered_frame.dispatch_tree.root_node_id());
 605
 606            cx.propagate_event = true;
 607            cx.dispatch_action_on_node(node_id, action);
 608        })
 609    }
 610
 611    pub(crate) fn dispatch_keystroke_observers(
 612        &mut self,
 613        event: &dyn Any,
 614        action: Option<Box<dyn Action>>,
 615    ) {
 616        let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() else {
 617            return;
 618        };
 619
 620        self.keystroke_observers
 621            .clone()
 622            .retain(&(), move |callback| {
 623                (callback)(
 624                    &KeystrokeEvent {
 625                        keystroke: key_down_event.keystroke.clone(),
 626                        action: action.as_ref().map(|action| action.boxed_clone()),
 627                    },
 628                    self,
 629                );
 630                true
 631            });
 632    }
 633
 634    pub(crate) fn clear_pending_keystrokes(&mut self) {
 635        self.window
 636            .rendered_frame
 637            .dispatch_tree
 638            .clear_pending_keystrokes();
 639        self.window
 640            .next_frame
 641            .dispatch_tree
 642            .clear_pending_keystrokes();
 643    }
 644
 645    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
 646    /// that are currently on the stack to be returned to the app.
 647    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
 648        let handle = self.window.handle;
 649        self.app.defer(move |cx| {
 650            handle.update(cx, |_, cx| f(cx)).ok();
 651        });
 652    }
 653
 654    /// Subscribe to events emitted by a model or view.
 655    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
 656    /// The callback will be invoked a handle to the emitting entity (either a [`View`] or [`Model`]), the event, and a window context for the current window.
 657    pub fn subscribe<Emitter, E, Evt>(
 658        &mut self,
 659        entity: &E,
 660        mut on_event: impl FnMut(E, &Evt, &mut WindowContext<'_>) + 'static,
 661    ) -> Subscription
 662    where
 663        Emitter: EventEmitter<Evt>,
 664        E: Entity<Emitter>,
 665        Evt: 'static,
 666    {
 667        let entity_id = entity.entity_id();
 668        let entity = entity.downgrade();
 669        let window_handle = self.window.handle;
 670        self.app.new_subscription(
 671            entity_id,
 672            (
 673                TypeId::of::<Evt>(),
 674                Box::new(move |event, cx| {
 675                    window_handle
 676                        .update(cx, |_, cx| {
 677                            if let Some(handle) = E::upgrade_from(&entity) {
 678                                let event = event.downcast_ref().expect("invalid event type");
 679                                on_event(handle, event, cx);
 680                                true
 681                            } else {
 682                                false
 683                            }
 684                        })
 685                        .unwrap_or(false)
 686                }),
 687            ),
 688        )
 689    }
 690
 691    /// Creates an [`AsyncWindowContext`], which has a static lifetime and can be held across
 692    /// await points in async code.
 693    pub fn to_async(&self) -> AsyncWindowContext {
 694        AsyncWindowContext::new(self.app.to_async(), self.window.handle)
 695    }
 696
 697    /// Schedule the given closure to be run directly after the current frame is rendered.
 698    pub fn on_next_frame(&mut self, callback: impl FnOnce(&mut WindowContext) + 'static) {
 699        RefCell::borrow_mut(&self.window.next_frame_callbacks).push(Box::new(callback));
 700    }
 701
 702    /// Spawn the future returned by the given closure on the application thread pool.
 703    /// The closure is provided a handle to the current window and an `AsyncWindowContext` for
 704    /// use within your future.
 705    pub fn spawn<Fut, R>(&mut self, f: impl FnOnce(AsyncWindowContext) -> Fut) -> Task<R>
 706    where
 707        R: 'static,
 708        Fut: Future<Output = R> + 'static,
 709    {
 710        self.app
 711            .spawn(|app| f(AsyncWindowContext::new(app, self.window.handle)))
 712    }
 713
 714    /// Updates the global of the given type. The given closure is given simultaneous mutable
 715    /// access both to the global and the context.
 716    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
 717    where
 718        G: Global,
 719    {
 720        let mut global = self.app.lease_global::<G>();
 721        let result = f(&mut global, self);
 722        self.app.end_global_lease(global);
 723        result
 724    }
 725
 726    fn window_bounds_changed(&mut self) {
 727        self.window.scale_factor = self.window.platform_window.scale_factor();
 728        self.window.viewport_size = self.window.platform_window.content_size();
 729        self.window.bounds = self.window.platform_window.bounds();
 730        self.window.display_id = self.window.platform_window.display().id();
 731        self.refresh();
 732
 733        self.window
 734            .bounds_observers
 735            .clone()
 736            .retain(&(), |callback| callback(self));
 737    }
 738
 739    /// Returns the bounds of the current window in the global coordinate space, which could span across multiple displays.
 740    pub fn window_bounds(&self) -> WindowBounds {
 741        self.window.bounds
 742    }
 743
 744    fn appearance_changed(&mut self) {
 745        self.window.appearance = self.window.platform_window.appearance();
 746
 747        self.window
 748            .appearance_observers
 749            .clone()
 750            .retain(&(), |callback| callback(self));
 751    }
 752
 753    /// Returns the appearance of the current window.
 754    pub fn appearance(&self) -> WindowAppearance {
 755        self.window.appearance
 756    }
 757
 758    /// Returns the size of the drawable area within the window.
 759    pub fn viewport_size(&self) -> Size<Pixels> {
 760        self.window.viewport_size
 761    }
 762
 763    /// Returns whether this window is focused by the operating system (receiving key events).
 764    pub fn is_window_active(&self) -> bool {
 765        self.window.active.get()
 766    }
 767
 768    /// Toggle zoom on the window.
 769    pub fn zoom_window(&self) {
 770        self.window.platform_window.zoom();
 771    }
 772
 773    /// Updates the window's title at the platform level.
 774    pub fn set_window_title(&mut self, title: &str) {
 775        self.window.platform_window.set_title(title);
 776    }
 777
 778    /// Mark the window as dirty at the platform level.
 779    pub fn set_window_edited(&mut self, edited: bool) {
 780        self.window.platform_window.set_edited(edited);
 781    }
 782
 783    /// Determine the display on which the window is visible.
 784    pub fn display(&self) -> Option<Rc<dyn PlatformDisplay>> {
 785        self.platform
 786            .displays()
 787            .into_iter()
 788            .find(|display| display.id() == self.window.display_id)
 789    }
 790
 791    /// Show the platform character palette.
 792    pub fn show_character_palette(&self) {
 793        self.window.platform_window.show_character_palette();
 794    }
 795
 796    /// The scale factor of the display associated with the window. For example, it could
 797    /// return 2.0 for a "retina" display, indicating that each logical pixel should actually
 798    /// be rendered as two pixels on screen.
 799    pub fn scale_factor(&self) -> f32 {
 800        self.window.scale_factor
 801    }
 802
 803    /// The size of an em for the base font of the application. Adjusting this value allows the
 804    /// UI to scale, just like zooming a web page.
 805    pub fn rem_size(&self) -> Pixels {
 806        self.window.rem_size
 807    }
 808
 809    /// Sets the size of an em for the base font of the application. Adjusting this value allows the
 810    /// UI to scale, just like zooming a web page.
 811    pub fn set_rem_size(&mut self, rem_size: impl Into<Pixels>) {
 812        self.window.rem_size = rem_size.into();
 813    }
 814
 815    /// The line height associated with the current text style.
 816    pub fn line_height(&self) -> Pixels {
 817        let rem_size = self.rem_size();
 818        let text_style = self.text_style();
 819        text_style
 820            .line_height
 821            .to_pixels(text_style.font_size, rem_size)
 822    }
 823
 824    /// Call to prevent the default action of an event. Currently only used to prevent
 825    /// parent elements from becoming focused on mouse down.
 826    pub fn prevent_default(&mut self) {
 827        self.window.default_prevented = true;
 828    }
 829
 830    /// Obtain whether default has been prevented for the event currently being dispatched.
 831    pub fn default_prevented(&self) -> bool {
 832        self.window.default_prevented
 833    }
 834
 835    /// Determine whether the given action is available along the dispatch path to the currently focused element.
 836    pub fn is_action_available(&self, action: &dyn Action) -> bool {
 837        let target = self
 838            .focused()
 839            .and_then(|focused_handle| {
 840                self.window
 841                    .rendered_frame
 842                    .dispatch_tree
 843                    .focusable_node_id(focused_handle.id)
 844            })
 845            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
 846        self.window
 847            .rendered_frame
 848            .dispatch_tree
 849            .is_action_available(action, target)
 850    }
 851
 852    /// The position of the mouse relative to the window.
 853    pub fn mouse_position(&self) -> Point<Pixels> {
 854        self.window.mouse_position
 855    }
 856
 857    /// The current state of the keyboard's modifiers
 858    pub fn modifiers(&self) -> Modifiers {
 859        self.window.modifiers
 860    }
 861
 862    /// Returns true if there is no opaque layer containing the given point
 863    /// on top of the given level. Layers who are extensions of the queried layer
 864    /// are not considered to be on top of queried layer.
 865    pub fn was_top_layer(&self, point: &Point<Pixels>, layer: &StackingOrder) -> bool {
 866        // Precondition: the depth map is ordered from topmost to bottomost.
 867
 868        for (opaque_layer, _, bounds) in self.window.rendered_frame.depth_map.iter() {
 869            if layer >= opaque_layer {
 870                // The queried layer is either above or is the same as the this opaque layer.
 871                // Anything after this point is guaranteed to be below the queried layer.
 872                return true;
 873            }
 874
 875            if !bounds.contains(point) {
 876                // This opaque layer is above the queried layer but it doesn't contain
 877                // the given position, so we can ignore it even if it's above.
 878                continue;
 879            }
 880
 881            // At this point, we've established that this opaque layer is on top of the queried layer
 882            // and contains the position:
 883            // If neither the opaque layer or the queried layer is an extension of the other then
 884            // we know they are on different stacking orders, and return false.
 885            let is_on_same_layer = opaque_layer
 886                .iter()
 887                .zip(layer.iter())
 888                .all(|(a, b)| a.z_index == b.z_index);
 889
 890            if !is_on_same_layer {
 891                return false;
 892            }
 893        }
 894
 895        true
 896    }
 897
 898    pub(crate) fn was_top_layer_under_active_drag(
 899        &self,
 900        point: &Point<Pixels>,
 901        layer: &StackingOrder,
 902    ) -> bool {
 903        // Precondition: the depth map is ordered from topmost to bottomost.
 904
 905        for (opaque_layer, _, bounds) in self.window.rendered_frame.depth_map.iter() {
 906            if layer >= opaque_layer {
 907                // The queried layer is either above or is the same as the this opaque layer.
 908                // Anything after this point is guaranteed to be below the queried layer.
 909                return true;
 910            }
 911
 912            if !bounds.contains(point) {
 913                // This opaque layer is above the queried layer but it doesn't contain
 914                // the given position, so we can ignore it even if it's above.
 915                continue;
 916            }
 917
 918            // All normal content is rendered with a base z-index of 0, we know that if the root of this opaque layer
 919            // equals `ACTIVE_DRAG_Z_INDEX` then it must be the drag layer and we can ignore it as we are
 920            // looking to see if the queried layer was the topmost underneath the drag layer.
 921            if opaque_layer
 922                .first()
 923                .map(|c| c.z_index == ACTIVE_DRAG_Z_INDEX)
 924                .unwrap_or(false)
 925            {
 926                continue;
 927            }
 928
 929            // At this point, we've established that this opaque layer is on top of the queried layer
 930            // and contains the position:
 931            // If neither the opaque layer or the queried layer is an extension of the other then
 932            // we know they are on different stacking orders, and return false.
 933            let is_on_same_layer = opaque_layer
 934                .iter()
 935                .zip(layer.iter())
 936                .all(|(a, b)| a.z_index == b.z_index);
 937
 938            if !is_on_same_layer {
 939                return false;
 940            }
 941        }
 942
 943        true
 944    }
 945
 946    /// Called during painting to get the current stacking order.
 947    pub fn stacking_order(&self) -> &StackingOrder {
 948        &self.window.next_frame.z_index_stack
 949    }
 950
 951    /// Produces a new frame and assigns it to `rendered_frame`. To actually show
 952    /// the contents of the new [Scene], use [present].
 953    #[profiling::function]
 954    pub fn draw(&mut self) {
 955        self.window.dirty.set(false);
 956        self.window.drawing = true;
 957
 958        if let Some(requested_handler) = self.window.rendered_frame.requested_input_handler.as_mut()
 959        {
 960            let input_handler = self.window.platform_window.take_input_handler();
 961            requested_handler.handler = input_handler;
 962        }
 963
 964        let root_view = self.window.root_view.take().unwrap();
 965        self.with_element_context(|cx| {
 966            cx.with_z_index(0, |cx| {
 967                cx.with_key_dispatch(Some(KeyContext::default()), None, |_, cx| {
 968                    // We need to use cx.cx here so we can utilize borrow splitting
 969                    for (action_type, action_listeners) in &cx.cx.app.global_action_listeners {
 970                        for action_listener in action_listeners.iter().cloned() {
 971                            cx.cx.window.next_frame.dispatch_tree.on_action(
 972                                *action_type,
 973                                Rc::new(
 974                                    move |action: &dyn Any, phase, cx: &mut WindowContext<'_>| {
 975                                        action_listener(action, phase, cx)
 976                                    },
 977                                ),
 978                            )
 979                        }
 980                    }
 981
 982                    let available_space = cx.window.viewport_size.map(Into::into);
 983                    root_view.draw(Point::default(), available_space, cx);
 984                })
 985            })
 986        });
 987
 988        if let Some(active_drag) = self.app.active_drag.take() {
 989            self.with_element_context(|cx| {
 990                cx.with_z_index(ACTIVE_DRAG_Z_INDEX, |cx| {
 991                    let offset = cx.mouse_position() - active_drag.cursor_offset;
 992                    let available_space =
 993                        size(AvailableSpace::MinContent, AvailableSpace::MinContent);
 994                    active_drag.view.draw(offset, available_space, cx);
 995                })
 996            });
 997            self.active_drag = Some(active_drag);
 998        } else if let Some(tooltip_request) = self.window.next_frame.tooltip_request.take() {
 999            self.with_element_context(|cx| {
1000                cx.with_z_index(1, |cx| {
1001                    let available_space =
1002                        size(AvailableSpace::MinContent, AvailableSpace::MinContent);
1003                    tooltip_request.tooltip.view.draw(
1004                        tooltip_request.tooltip.cursor_offset,
1005                        available_space,
1006                        cx,
1007                    );
1008                })
1009            });
1010            self.window.next_frame.tooltip_request = Some(tooltip_request);
1011        }
1012        self.window.dirty_views.clear();
1013
1014        self.window
1015            .next_frame
1016            .dispatch_tree
1017            .preserve_pending_keystrokes(
1018                &mut self.window.rendered_frame.dispatch_tree,
1019                self.window.focus,
1020            );
1021        self.window.next_frame.focus = self.window.focus;
1022        self.window.next_frame.window_active = self.window.active.get();
1023        self.window.root_view = Some(root_view);
1024
1025        // Set the cursor only if we're the active window.
1026        let cursor_style = self
1027            .window
1028            .next_frame
1029            .requested_cursor_style
1030            .take()
1031            .unwrap_or(CursorStyle::Arrow);
1032        if self.is_window_active() {
1033            self.platform.set_cursor_style(cursor_style);
1034        }
1035
1036        // Register requested input handler with the platform window.
1037        if let Some(requested_input) = self.window.next_frame.requested_input_handler.as_mut() {
1038            if let Some(handler) = requested_input.handler.take() {
1039                self.window.platform_window.set_input_handler(handler);
1040            }
1041        }
1042
1043        self.window.layout_engine.as_mut().unwrap().clear();
1044        self.text_system()
1045            .finish_frame(&self.window.next_frame.reused_views);
1046        self.window
1047            .next_frame
1048            .finish(&mut self.window.rendered_frame);
1049        ELEMENT_ARENA.with_borrow_mut(|element_arena| {
1050            let percentage = (element_arena.len() as f32 / element_arena.capacity() as f32) * 100.;
1051            if percentage >= 80. {
1052                log::warn!("elevated element arena occupation: {}.", percentage);
1053            }
1054            element_arena.clear();
1055        });
1056
1057        let previous_focus_path = self.window.rendered_frame.focus_path();
1058        let previous_window_active = self.window.rendered_frame.window_active;
1059        mem::swap(&mut self.window.rendered_frame, &mut self.window.next_frame);
1060        self.window.next_frame.clear();
1061        let current_focus_path = self.window.rendered_frame.focus_path();
1062        let current_window_active = self.window.rendered_frame.window_active;
1063
1064        if previous_focus_path != current_focus_path
1065            || previous_window_active != current_window_active
1066        {
1067            if !previous_focus_path.is_empty() && current_focus_path.is_empty() {
1068                self.window
1069                    .focus_lost_listeners
1070                    .clone()
1071                    .retain(&(), |listener| listener(self));
1072            }
1073
1074            let event = FocusEvent {
1075                previous_focus_path: if previous_window_active {
1076                    previous_focus_path
1077                } else {
1078                    Default::default()
1079                },
1080                current_focus_path: if current_window_active {
1081                    current_focus_path
1082                } else {
1083                    Default::default()
1084                },
1085            };
1086            self.window
1087                .focus_listeners
1088                .clone()
1089                .retain(&(), |listener| listener(&event, self));
1090        }
1091        self.window.refreshing = false;
1092        self.window.drawing = false;
1093        self.window.needs_present.set(true);
1094    }
1095
1096    #[profiling::function]
1097    fn present(&self) {
1098        self.window
1099            .platform_window
1100            .draw(&self.window.rendered_frame.scene);
1101        self.window.needs_present.set(false);
1102        profiling::finish_frame!();
1103    }
1104
1105    /// Dispatch a given keystroke as though the user had typed it.
1106    /// You can create a keystroke with Keystroke::parse("").
1107    pub fn dispatch_keystroke(&mut self, mut keystroke: Keystroke) -> bool {
1108        if keystroke.ime_key.is_none()
1109            && !keystroke.modifiers.command
1110            && !keystroke.modifiers.control
1111            && !keystroke.modifiers.function
1112        {
1113            keystroke.ime_key = Some(if keystroke.modifiers.shift {
1114                keystroke.key.to_uppercase().clone()
1115            } else {
1116                keystroke.key.clone()
1117            })
1118        }
1119        if self.dispatch_event(PlatformInput::KeyDown(KeyDownEvent {
1120            keystroke: keystroke.clone(),
1121            is_held: false,
1122        })) {
1123            return true;
1124        }
1125
1126        if let Some(input) = keystroke.ime_key {
1127            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1128                input_handler.dispatch_input(&input, self);
1129                self.window.platform_window.set_input_handler(input_handler);
1130                return true;
1131            }
1132        }
1133
1134        false
1135    }
1136
1137    /// Dispatch a mouse or keyboard event on the window.
1138    #[profiling::function]
1139    pub fn dispatch_event(&mut self, event: PlatformInput) -> bool {
1140        self.window.last_input_timestamp.set(Instant::now());
1141        // Handlers may set this to false by calling `stop_propagation`.
1142        self.app.propagate_event = true;
1143        // Handlers may set this to true by calling `prevent_default`.
1144        self.window.default_prevented = false;
1145
1146        let event = match event {
1147            // Track the mouse position with our own state, since accessing the platform
1148            // API for the mouse position can only occur on the main thread.
1149            PlatformInput::MouseMove(mouse_move) => {
1150                self.window.mouse_position = mouse_move.position;
1151                self.window.modifiers = mouse_move.modifiers;
1152                PlatformInput::MouseMove(mouse_move)
1153            }
1154            PlatformInput::MouseDown(mouse_down) => {
1155                self.window.mouse_position = mouse_down.position;
1156                self.window.modifiers = mouse_down.modifiers;
1157                PlatformInput::MouseDown(mouse_down)
1158            }
1159            PlatformInput::MouseUp(mouse_up) => {
1160                self.window.mouse_position = mouse_up.position;
1161                self.window.modifiers = mouse_up.modifiers;
1162                PlatformInput::MouseUp(mouse_up)
1163            }
1164            PlatformInput::MouseExited(mouse_exited) => {
1165                self.window.modifiers = mouse_exited.modifiers;
1166                PlatformInput::MouseExited(mouse_exited)
1167            }
1168            PlatformInput::ModifiersChanged(modifiers_changed) => {
1169                self.window.modifiers = modifiers_changed.modifiers;
1170                PlatformInput::ModifiersChanged(modifiers_changed)
1171            }
1172            PlatformInput::ScrollWheel(scroll_wheel) => {
1173                self.window.mouse_position = scroll_wheel.position;
1174                self.window.modifiers = scroll_wheel.modifiers;
1175                PlatformInput::ScrollWheel(scroll_wheel)
1176            }
1177            // Translate dragging and dropping of external files from the operating system
1178            // to internal drag and drop events.
1179            PlatformInput::FileDrop(file_drop) => match file_drop {
1180                FileDropEvent::Entered { position, paths } => {
1181                    self.window.mouse_position = position;
1182                    if self.active_drag.is_none() {
1183                        self.active_drag = Some(AnyDrag {
1184                            value: Box::new(paths.clone()),
1185                            view: self.new_view(|_| paths).into(),
1186                            cursor_offset: position,
1187                        });
1188                    }
1189                    PlatformInput::MouseMove(MouseMoveEvent {
1190                        position,
1191                        pressed_button: Some(MouseButton::Left),
1192                        modifiers: Modifiers::default(),
1193                    })
1194                }
1195                FileDropEvent::Pending { position } => {
1196                    self.window.mouse_position = position;
1197                    PlatformInput::MouseMove(MouseMoveEvent {
1198                        position,
1199                        pressed_button: Some(MouseButton::Left),
1200                        modifiers: Modifiers::default(),
1201                    })
1202                }
1203                FileDropEvent::Submit { position } => {
1204                    self.activate(true);
1205                    self.window.mouse_position = position;
1206                    PlatformInput::MouseUp(MouseUpEvent {
1207                        button: MouseButton::Left,
1208                        position,
1209                        modifiers: Modifiers::default(),
1210                        click_count: 1,
1211                    })
1212                }
1213                FileDropEvent::Exited => PlatformInput::MouseUp(MouseUpEvent {
1214                    button: MouseButton::Left,
1215                    position: Point::default(),
1216                    modifiers: Modifiers::default(),
1217                    click_count: 1,
1218                }),
1219            },
1220            PlatformInput::KeyDown(_) | PlatformInput::KeyUp(_) => event,
1221        };
1222
1223        if let Some(any_mouse_event) = event.mouse_event() {
1224            self.dispatch_mouse_event(any_mouse_event);
1225        } else if let Some(any_key_event) = event.keyboard_event() {
1226            self.dispatch_key_event(any_key_event);
1227        }
1228
1229        !self.app.propagate_event
1230    }
1231
1232    fn dispatch_mouse_event(&mut self, event: &dyn Any) {
1233        if let Some(mut handlers) = self
1234            .window
1235            .rendered_frame
1236            .mouse_listeners
1237            .remove(&event.type_id())
1238        {
1239            // Because handlers may add other handlers, we sort every time.
1240            handlers.sort_by(|(a, _, _), (b, _, _)| a.cmp(b));
1241
1242            // Capture phase, events bubble from back to front. Handlers for this phase are used for
1243            // special purposes, such as detecting events outside of a given Bounds.
1244            for (_, _, handler) in &mut handlers {
1245                self.with_element_context(|cx| {
1246                    handler(event, DispatchPhase::Capture, cx);
1247                });
1248                if !self.app.propagate_event {
1249                    break;
1250                }
1251            }
1252
1253            // Bubble phase, where most normal handlers do their work.
1254            if self.app.propagate_event {
1255                for (_, _, handler) in handlers.iter_mut().rev() {
1256                    self.with_element_context(|cx| {
1257                        handler(event, DispatchPhase::Bubble, cx);
1258                    });
1259                    if !self.app.propagate_event {
1260                        break;
1261                    }
1262                }
1263            }
1264
1265            self.window
1266                .rendered_frame
1267                .mouse_listeners
1268                .insert(event.type_id(), handlers);
1269        }
1270
1271        if self.app.propagate_event && self.has_active_drag() {
1272            if event.is::<MouseMoveEvent>() {
1273                // If this was a mouse move event, redraw the window so that the
1274                // active drag can follow the mouse cursor.
1275                self.refresh();
1276            } else if event.is::<MouseUpEvent>() {
1277                // If this was a mouse up event, cancel the active drag and redraw
1278                // the window.
1279                self.active_drag = None;
1280                self.refresh();
1281            }
1282        }
1283    }
1284
1285    fn dispatch_key_event(&mut self, event: &dyn Any) {
1286        if self.window.dirty.get() {
1287            self.draw();
1288        }
1289
1290        let node_id = self
1291            .window
1292            .focus
1293            .and_then(|focus_id| {
1294                self.window
1295                    .rendered_frame
1296                    .dispatch_tree
1297                    .focusable_node_id(focus_id)
1298            })
1299            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1300
1301        let dispatch_path = self
1302            .window
1303            .rendered_frame
1304            .dispatch_tree
1305            .dispatch_path(node_id);
1306
1307        if let Some(key_down_event) = event.downcast_ref::<KeyDownEvent>() {
1308            let KeymatchResult { bindings, pending } = self
1309                .window
1310                .rendered_frame
1311                .dispatch_tree
1312                .dispatch_key(&key_down_event.keystroke, &dispatch_path);
1313
1314            if pending {
1315                let mut currently_pending = self.window.pending_input.take().unwrap_or_default();
1316                if currently_pending.focus.is_some() && currently_pending.focus != self.window.focus
1317                {
1318                    currently_pending = PendingInput::default();
1319                }
1320                currently_pending.focus = self.window.focus;
1321                currently_pending
1322                    .keystrokes
1323                    .push(key_down_event.keystroke.clone());
1324                for binding in bindings {
1325                    currently_pending.bindings.push(binding);
1326                }
1327
1328                currently_pending.timer = Some(self.spawn(|mut cx| async move {
1329                    cx.background_executor.timer(Duration::from_secs(1)).await;
1330                    cx.update(move |cx| {
1331                        cx.clear_pending_keystrokes();
1332                        let Some(currently_pending) = cx.window.pending_input.take() else {
1333                            return;
1334                        };
1335                        cx.replay_pending_input(currently_pending)
1336                    })
1337                    .log_err();
1338                }));
1339                self.window.pending_input = Some(currently_pending);
1340
1341                self.propagate_event = false;
1342                return;
1343            } else if let Some(currently_pending) = self.window.pending_input.take() {
1344                if bindings
1345                    .iter()
1346                    .all(|binding| !currently_pending.used_by_binding(binding))
1347                {
1348                    self.replay_pending_input(currently_pending)
1349                }
1350            }
1351
1352            if !bindings.is_empty() {
1353                self.clear_pending_keystrokes();
1354            }
1355
1356            self.propagate_event = true;
1357            for binding in bindings {
1358                self.dispatch_action_on_node(node_id, binding.action.boxed_clone());
1359                if !self.propagate_event {
1360                    self.dispatch_keystroke_observers(event, Some(binding.action));
1361                    return;
1362                }
1363            }
1364        }
1365
1366        self.dispatch_key_down_up_event(event, &dispatch_path);
1367        if !self.propagate_event {
1368            return;
1369        }
1370
1371        self.dispatch_keystroke_observers(event, None);
1372    }
1373
1374    fn dispatch_key_down_up_event(
1375        &mut self,
1376        event: &dyn Any,
1377        dispatch_path: &SmallVec<[DispatchNodeId; 32]>,
1378    ) {
1379        // Capture phase
1380        for node_id in dispatch_path {
1381            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1382
1383            for key_listener in node.key_listeners.clone() {
1384                self.with_element_context(|cx| {
1385                    key_listener(event, DispatchPhase::Capture, cx);
1386                });
1387                if !self.propagate_event {
1388                    return;
1389                }
1390            }
1391        }
1392
1393        // Bubble phase
1394        for node_id in dispatch_path.iter().rev() {
1395            // Handle low level key events
1396            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1397            for key_listener in node.key_listeners.clone() {
1398                self.with_element_context(|cx| {
1399                    key_listener(event, DispatchPhase::Bubble, cx);
1400                });
1401                if !self.propagate_event {
1402                    return;
1403                }
1404            }
1405        }
1406    }
1407
1408    /// Determine whether a potential multi-stroke key binding is in progress on this window.
1409    pub fn has_pending_keystrokes(&self) -> bool {
1410        self.window
1411            .rendered_frame
1412            .dispatch_tree
1413            .has_pending_keystrokes()
1414    }
1415
1416    fn replay_pending_input(&mut self, currently_pending: PendingInput) {
1417        let node_id = self
1418            .window
1419            .focus
1420            .and_then(|focus_id| {
1421                self.window
1422                    .rendered_frame
1423                    .dispatch_tree
1424                    .focusable_node_id(focus_id)
1425            })
1426            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1427
1428        if self.window.focus != currently_pending.focus {
1429            return;
1430        }
1431
1432        let input = currently_pending.input();
1433
1434        self.propagate_event = true;
1435        for binding in currently_pending.bindings {
1436            self.dispatch_action_on_node(node_id, binding.action.boxed_clone());
1437            if !self.propagate_event {
1438                return;
1439            }
1440        }
1441
1442        let dispatch_path = self
1443            .window
1444            .rendered_frame
1445            .dispatch_tree
1446            .dispatch_path(node_id);
1447
1448        for keystroke in currently_pending.keystrokes {
1449            let event = KeyDownEvent {
1450                keystroke,
1451                is_held: false,
1452            };
1453
1454            self.dispatch_key_down_up_event(&event, &dispatch_path);
1455            if !self.propagate_event {
1456                return;
1457            }
1458        }
1459
1460        if !input.is_empty() {
1461            if let Some(mut input_handler) = self.window.platform_window.take_input_handler() {
1462                input_handler.dispatch_input(&input, self);
1463                self.window.platform_window.set_input_handler(input_handler)
1464            }
1465        }
1466    }
1467
1468    fn dispatch_action_on_node(&mut self, node_id: DispatchNodeId, action: Box<dyn Action>) {
1469        let dispatch_path = self
1470            .window
1471            .rendered_frame
1472            .dispatch_tree
1473            .dispatch_path(node_id);
1474
1475        // Capture phase
1476        for node_id in &dispatch_path {
1477            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1478            for DispatchActionListener {
1479                action_type,
1480                listener,
1481            } in node.action_listeners.clone()
1482            {
1483                let any_action = action.as_any();
1484                if action_type == any_action.type_id() {
1485                    self.with_element_context(|cx| {
1486                        listener(any_action, DispatchPhase::Capture, cx);
1487                    });
1488
1489                    if !self.propagate_event {
1490                        return;
1491                    }
1492                }
1493            }
1494        }
1495        // Bubble phase
1496        for node_id in dispatch_path.iter().rev() {
1497            let node = self.window.rendered_frame.dispatch_tree.node(*node_id);
1498            for DispatchActionListener {
1499                action_type,
1500                listener,
1501            } in node.action_listeners.clone()
1502            {
1503                let any_action = action.as_any();
1504                if action_type == any_action.type_id() {
1505                    self.propagate_event = false; // Actions stop propagation by default during the bubble phase
1506
1507                    self.with_element_context(|cx| {
1508                        listener(any_action, DispatchPhase::Bubble, cx);
1509                    });
1510
1511                    if !self.propagate_event {
1512                        return;
1513                    }
1514                }
1515            }
1516        }
1517    }
1518
1519    /// Toggle the graphics profiler to debug your application's rendering performance.
1520    pub fn toggle_graphics_profiler(&mut self) {
1521        self.window.graphics_profiler_enabled = !self.window.graphics_profiler_enabled;
1522        self.window
1523            .platform_window
1524            .set_graphics_profiler_enabled(self.window.graphics_profiler_enabled);
1525    }
1526
1527    /// Register the given handler to be invoked whenever the global of the given type
1528    /// is updated.
1529    pub fn observe_global<G: Global>(
1530        &mut self,
1531        f: impl Fn(&mut WindowContext<'_>) + 'static,
1532    ) -> Subscription {
1533        let window_handle = self.window.handle;
1534        let (subscription, activate) = self.global_observers.insert(
1535            TypeId::of::<G>(),
1536            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
1537        );
1538        self.app.defer(move |_| activate());
1539        subscription
1540    }
1541
1542    /// Focus the current window and bring it to the foreground at the platform level.
1543    pub fn activate_window(&self) {
1544        self.window.platform_window.activate();
1545    }
1546
1547    /// Minimize the current window at the platform level.
1548    pub fn minimize_window(&self) {
1549        self.window.platform_window.minimize();
1550    }
1551
1552    /// Toggle full screen status on the current window at the platform level.
1553    pub fn toggle_full_screen(&self) {
1554        self.window.platform_window.toggle_full_screen();
1555    }
1556
1557    /// Present a platform dialog.
1558    /// The provided message will be presented, along with buttons for each answer.
1559    /// When a button is clicked, the returned Receiver will receive the index of the clicked button.
1560    pub fn prompt(
1561        &self,
1562        level: PromptLevel,
1563        message: &str,
1564        detail: Option<&str>,
1565        answers: &[&str],
1566    ) -> oneshot::Receiver<usize> {
1567        self.window
1568            .platform_window
1569            .prompt(level, message, detail, answers)
1570    }
1571
1572    /// Returns all available actions for the focused element.
1573    pub fn available_actions(&self) -> Vec<Box<dyn Action>> {
1574        let node_id = self
1575            .window
1576            .focus
1577            .and_then(|focus_id| {
1578                self.window
1579                    .rendered_frame
1580                    .dispatch_tree
1581                    .focusable_node_id(focus_id)
1582            })
1583            .unwrap_or_else(|| self.window.rendered_frame.dispatch_tree.root_node_id());
1584
1585        self.window
1586            .rendered_frame
1587            .dispatch_tree
1588            .available_actions(node_id)
1589    }
1590
1591    /// Returns key bindings that invoke the given action on the currently focused element.
1592    pub fn bindings_for_action(&self, action: &dyn Action) -> Vec<KeyBinding> {
1593        self.window
1594            .rendered_frame
1595            .dispatch_tree
1596            .bindings_for_action(
1597                action,
1598                &self.window.rendered_frame.dispatch_tree.context_stack,
1599            )
1600    }
1601
1602    /// Returns any bindings that would invoke the given action on the given focus handle if it were focused.
1603    pub fn bindings_for_action_in(
1604        &self,
1605        action: &dyn Action,
1606        focus_handle: &FocusHandle,
1607    ) -> Vec<KeyBinding> {
1608        let dispatch_tree = &self.window.rendered_frame.dispatch_tree;
1609
1610        let Some(node_id) = dispatch_tree.focusable_node_id(focus_handle.id) else {
1611            return vec![];
1612        };
1613        let context_stack: Vec<_> = dispatch_tree
1614            .dispatch_path(node_id)
1615            .into_iter()
1616            .filter_map(|node_id| dispatch_tree.node(node_id).context.clone())
1617            .collect();
1618        dispatch_tree.bindings_for_action(action, &context_stack)
1619    }
1620
1621    /// Returns a generic event listener that invokes the given listener with the view and context associated with the given view handle.
1622    pub fn listener_for<V: Render, E>(
1623        &self,
1624        view: &View<V>,
1625        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
1626    ) -> impl Fn(&E, &mut WindowContext) + 'static {
1627        let view = view.downgrade();
1628        move |e: &E, cx: &mut WindowContext| {
1629            view.update(cx, |view, cx| f(view, e, cx)).ok();
1630        }
1631    }
1632
1633    /// Returns a generic handler that invokes the given handler with the view and context associated with the given view handle.
1634    pub fn handler_for<V: Render>(
1635        &self,
1636        view: &View<V>,
1637        f: impl Fn(&mut V, &mut ViewContext<V>) + 'static,
1638    ) -> impl Fn(&mut WindowContext) {
1639        let view = view.downgrade();
1640        move |cx: &mut WindowContext| {
1641            view.update(cx, |view, cx| f(view, cx)).ok();
1642        }
1643    }
1644
1645    /// Register a callback that can interrupt the closing of the current window based the returned boolean.
1646    /// If the callback returns false, the window won't be closed.
1647    pub fn on_window_should_close(&mut self, f: impl Fn(&mut WindowContext) -> bool + 'static) {
1648        let mut this = self.to_async();
1649        self.window
1650            .platform_window
1651            .on_should_close(Box::new(move || this.update(|cx| f(cx)).unwrap_or(true)))
1652    }
1653
1654    pub(crate) fn parent_view_id(&self) -> EntityId {
1655        *self
1656            .window
1657            .next_frame
1658            .view_stack
1659            .last()
1660            .expect("a view should always be on the stack while drawing")
1661    }
1662
1663    /// Register an action listener on the window for the next frame. The type of action
1664    /// is determined by the first parameter of the given listener. When the next frame is rendered
1665    /// the listener will be cleared.
1666    ///
1667    /// This is a fairly low-level method, so prefer using action handlers on elements unless you have
1668    /// a specific need to register a global listener.
1669    pub fn on_action(
1670        &mut self,
1671        action_type: TypeId,
1672        listener: impl Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static,
1673    ) {
1674        self.window
1675            .next_frame
1676            .dispatch_tree
1677            .on_action(action_type, Rc::new(listener));
1678    }
1679}
1680
1681impl Context for WindowContext<'_> {
1682    type Result<T> = T;
1683
1684    fn new_model<T>(&mut self, build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T) -> Model<T>
1685    where
1686        T: 'static,
1687    {
1688        let slot = self.app.entities.reserve();
1689        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
1690        self.entities.insert(slot, model)
1691    }
1692
1693    fn update_model<T: 'static, R>(
1694        &mut self,
1695        model: &Model<T>,
1696        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
1697    ) -> R {
1698        let mut entity = self.entities.lease(model);
1699        let result = update(
1700            &mut *entity,
1701            &mut ModelContext::new(&mut *self.app, model.downgrade()),
1702        );
1703        self.entities.end_lease(entity);
1704        result
1705    }
1706
1707    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
1708    where
1709        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
1710    {
1711        if window == self.window.handle {
1712            let root_view = self.window.root_view.clone().unwrap();
1713            Ok(update(root_view, self))
1714        } else {
1715            window.update(self.app, update)
1716        }
1717    }
1718
1719    fn read_model<T, R>(
1720        &self,
1721        handle: &Model<T>,
1722        read: impl FnOnce(&T, &AppContext) -> R,
1723    ) -> Self::Result<R>
1724    where
1725        T: 'static,
1726    {
1727        let entity = self.entities.read(handle);
1728        read(entity, &*self.app)
1729    }
1730
1731    fn read_window<T, R>(
1732        &self,
1733        window: &WindowHandle<T>,
1734        read: impl FnOnce(View<T>, &AppContext) -> R,
1735    ) -> Result<R>
1736    where
1737        T: 'static,
1738    {
1739        if window.any_handle == self.window.handle {
1740            let root_view = self
1741                .window
1742                .root_view
1743                .clone()
1744                .unwrap()
1745                .downcast::<T>()
1746                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
1747            Ok(read(root_view, self))
1748        } else {
1749            self.app.read_window(window, read)
1750        }
1751    }
1752}
1753
1754impl VisualContext for WindowContext<'_> {
1755    fn new_view<V>(
1756        &mut self,
1757        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1758    ) -> Self::Result<View<V>>
1759    where
1760        V: 'static + Render,
1761    {
1762        let slot = self.app.entities.reserve();
1763        let view = View {
1764            model: slot.clone(),
1765        };
1766        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
1767        let entity = build_view_state(&mut cx);
1768        cx.entities.insert(slot, entity);
1769
1770        // Non-generic part to avoid leaking SubscriberSet to invokers of `new_view`.
1771        fn notify_observers(cx: &mut WindowContext, tid: TypeId, view: AnyView) {
1772            cx.new_view_observers.clone().retain(&tid, |observer| {
1773                let any_view = view.clone();
1774                (observer)(any_view, cx);
1775                true
1776            });
1777        }
1778        notify_observers(self, TypeId::of::<V>(), AnyView::from(view.clone()));
1779
1780        view
1781    }
1782
1783    /// Updates the given view. Prefer calling [`View::update`] instead, which calls this method.
1784    fn update_view<T: 'static, R>(
1785        &mut self,
1786        view: &View<T>,
1787        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
1788    ) -> Self::Result<R> {
1789        let mut lease = self.app.entities.lease(&view.model);
1790        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, view);
1791        let result = update(&mut *lease, &mut cx);
1792        cx.app.entities.end_lease(lease);
1793        result
1794    }
1795
1796    fn replace_root_view<V>(
1797        &mut self,
1798        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
1799    ) -> Self::Result<View<V>>
1800    where
1801        V: 'static + Render,
1802    {
1803        let view = self.new_view(build_view);
1804        self.window.root_view = Some(view.clone().into());
1805        self.refresh();
1806        view
1807    }
1808
1809    fn focus_view<V: crate::FocusableView>(&mut self, view: &View<V>) -> Self::Result<()> {
1810        self.update_view(view, |view, cx| {
1811            view.focus_handle(cx).clone().focus(cx);
1812        })
1813    }
1814
1815    fn dismiss_view<V>(&mut self, view: &View<V>) -> Self::Result<()>
1816    where
1817        V: ManagedView,
1818    {
1819        self.update_view(view, |_, cx| cx.emit(DismissEvent))
1820    }
1821}
1822
1823impl<'a> std::ops::Deref for WindowContext<'a> {
1824    type Target = AppContext;
1825
1826    fn deref(&self) -> &Self::Target {
1827        self.app
1828    }
1829}
1830
1831impl<'a> std::ops::DerefMut for WindowContext<'a> {
1832    fn deref_mut(&mut self) -> &mut Self::Target {
1833        self.app
1834    }
1835}
1836
1837impl<'a> Borrow<AppContext> for WindowContext<'a> {
1838    fn borrow(&self) -> &AppContext {
1839        self.app
1840    }
1841}
1842
1843impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
1844    fn borrow_mut(&mut self) -> &mut AppContext {
1845        self.app
1846    }
1847}
1848
1849/// This trait contains functionality that is shared across [`ViewContext`] and [`WindowContext`]
1850pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
1851    #[doc(hidden)]
1852    fn app_mut(&mut self) -> &mut AppContext {
1853        self.borrow_mut()
1854    }
1855
1856    #[doc(hidden)]
1857    fn app(&self) -> &AppContext {
1858        self.borrow()
1859    }
1860
1861    #[doc(hidden)]
1862    fn window(&self) -> &Window {
1863        self.borrow()
1864    }
1865
1866    #[doc(hidden)]
1867    fn window_mut(&mut self) -> &mut Window {
1868        self.borrow_mut()
1869    }
1870}
1871
1872impl Borrow<Window> for WindowContext<'_> {
1873    fn borrow(&self) -> &Window {
1874        self.window
1875    }
1876}
1877
1878impl BorrowMut<Window> for WindowContext<'_> {
1879    fn borrow_mut(&mut self) -> &mut Window {
1880        self.window
1881    }
1882}
1883
1884impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
1885
1886/// Provides access to application state that is specialized for a particular [`View`].
1887/// Allows you to interact with focus, emit events, etc.
1888/// ViewContext also derefs to [`WindowContext`], giving you access to all of its methods as well.
1889/// When you call [`View::update`], you're passed a `&mut V` and an `&mut ViewContext<V>`.
1890pub struct ViewContext<'a, V> {
1891    window_cx: WindowContext<'a>,
1892    view: &'a View<V>,
1893}
1894
1895impl<V> Borrow<AppContext> for ViewContext<'_, V> {
1896    fn borrow(&self) -> &AppContext {
1897        &*self.window_cx.app
1898    }
1899}
1900
1901impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
1902    fn borrow_mut(&mut self) -> &mut AppContext {
1903        &mut *self.window_cx.app
1904    }
1905}
1906
1907impl<V> Borrow<Window> for ViewContext<'_, V> {
1908    fn borrow(&self) -> &Window {
1909        &*self.window_cx.window
1910    }
1911}
1912
1913impl<V> BorrowMut<Window> for ViewContext<'_, V> {
1914    fn borrow_mut(&mut self) -> &mut Window {
1915        &mut *self.window_cx.window
1916    }
1917}
1918
1919impl<'a, V: 'static> ViewContext<'a, V> {
1920    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
1921        Self {
1922            window_cx: WindowContext::new(app, window),
1923            view,
1924        }
1925    }
1926
1927    /// Get the entity_id of this view.
1928    pub fn entity_id(&self) -> EntityId {
1929        self.view.entity_id()
1930    }
1931
1932    /// Get the view pointer underlying this context.
1933    pub fn view(&self) -> &View<V> {
1934        self.view
1935    }
1936
1937    /// Get the model underlying this view.
1938    pub fn model(&self) -> &Model<V> {
1939        &self.view.model
1940    }
1941
1942    /// Access the underlying window context.
1943    pub fn window_context(&mut self) -> &mut WindowContext<'a> {
1944        &mut self.window_cx
1945    }
1946
1947    /// Sets a given callback to be run on the next frame.
1948    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
1949    where
1950        V: 'static,
1951    {
1952        let view = self.view().clone();
1953        self.window_cx.on_next_frame(move |cx| view.update(cx, f));
1954    }
1955
1956    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
1957    /// that are currently on the stack to be returned to the app.
1958    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
1959        let view = self.view().downgrade();
1960        self.window_cx.defer(move |cx| {
1961            view.update(cx, f).ok();
1962        });
1963    }
1964
1965    /// Observe another model or view for changes to its state, as tracked by [`ModelContext::notify`].
1966    pub fn observe<V2, E>(
1967        &mut self,
1968        entity: &E,
1969        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
1970    ) -> Subscription
1971    where
1972        V2: 'static,
1973        V: 'static,
1974        E: Entity<V2>,
1975    {
1976        let view = self.view().downgrade();
1977        let entity_id = entity.entity_id();
1978        let entity = entity.downgrade();
1979        let window_handle = self.window.handle;
1980        self.app.new_observer(
1981            entity_id,
1982            Box::new(move |cx| {
1983                window_handle
1984                    .update(cx, |_, cx| {
1985                        if let Some(handle) = E::upgrade_from(&entity) {
1986                            view.update(cx, |this, cx| on_notify(this, handle, cx))
1987                                .is_ok()
1988                        } else {
1989                            false
1990                        }
1991                    })
1992                    .unwrap_or(false)
1993            }),
1994        )
1995    }
1996
1997    /// Subscribe to events emitted by another model or view.
1998    /// The entity to which you're subscribing must implement the [`EventEmitter`] trait.
1999    /// 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.
2000    pub fn subscribe<V2, E, Evt>(
2001        &mut self,
2002        entity: &E,
2003        mut on_event: impl FnMut(&mut V, E, &Evt, &mut ViewContext<'_, V>) + 'static,
2004    ) -> Subscription
2005    where
2006        V2: EventEmitter<Evt>,
2007        E: Entity<V2>,
2008        Evt: 'static,
2009    {
2010        let view = self.view().downgrade();
2011        let entity_id = entity.entity_id();
2012        let handle = entity.downgrade();
2013        let window_handle = self.window.handle;
2014        self.app.new_subscription(
2015            entity_id,
2016            (
2017                TypeId::of::<Evt>(),
2018                Box::new(move |event, cx| {
2019                    window_handle
2020                        .update(cx, |_, cx| {
2021                            if let Some(handle) = E::upgrade_from(&handle) {
2022                                let event = event.downcast_ref().expect("invalid event type");
2023                                view.update(cx, |this, cx| on_event(this, handle, event, cx))
2024                                    .is_ok()
2025                            } else {
2026                                false
2027                            }
2028                        })
2029                        .unwrap_or(false)
2030                }),
2031            ),
2032        )
2033    }
2034
2035    /// Register a callback to be invoked when the view is released.
2036    ///
2037    /// The callback receives a handle to the view's window. This handle may be
2038    /// invalid, if the window was closed before the view was released.
2039    pub fn on_release(
2040        &mut self,
2041        on_release: impl FnOnce(&mut V, AnyWindowHandle, &mut AppContext) + 'static,
2042    ) -> Subscription {
2043        let window_handle = self.window.handle;
2044        let (subscription, activate) = self.app.release_listeners.insert(
2045            self.view.model.entity_id,
2046            Box::new(move |this, cx| {
2047                let this = this.downcast_mut().expect("invalid entity type");
2048                on_release(this, window_handle, cx)
2049            }),
2050        );
2051        activate();
2052        subscription
2053    }
2054
2055    /// Register a callback to be invoked when the given Model or View is released.
2056    pub fn observe_release<V2, E>(
2057        &mut self,
2058        entity: &E,
2059        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
2060    ) -> Subscription
2061    where
2062        V: 'static,
2063        V2: 'static,
2064        E: Entity<V2>,
2065    {
2066        let view = self.view().downgrade();
2067        let entity_id = entity.entity_id();
2068        let window_handle = self.window.handle;
2069        let (subscription, activate) = self.app.release_listeners.insert(
2070            entity_id,
2071            Box::new(move |entity, cx| {
2072                let entity = entity.downcast_mut().expect("invalid entity type");
2073                let _ = window_handle.update(cx, |_, cx| {
2074                    view.update(cx, |this, cx| on_release(this, entity, cx))
2075                });
2076            }),
2077        );
2078        activate();
2079        subscription
2080    }
2081
2082    /// Indicate that this view has changed, which will invoke any observers and also mark the window as dirty.
2083    /// If this view or any of its ancestors are *cached*, notifying it will cause it or its ancestors to be redrawn.
2084    pub fn notify(&mut self) {
2085        for view_id in self
2086            .window
2087            .rendered_frame
2088            .dispatch_tree
2089            .view_path(self.view.entity_id())
2090            .into_iter()
2091            .rev()
2092        {
2093            if !self.window.dirty_views.insert(view_id) {
2094                break;
2095            }
2096        }
2097
2098        if !self.window.drawing {
2099            self.window_cx.window.dirty.set(true);
2100            self.window_cx.app.push_effect(Effect::Notify {
2101                emitter: self.view.model.entity_id,
2102            });
2103        }
2104    }
2105
2106    /// Register a callback to be invoked when the window is resized.
2107    pub fn observe_window_bounds(
2108        &mut self,
2109        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2110    ) -> Subscription {
2111        let view = self.view.downgrade();
2112        let (subscription, activate) = self.window.bounds_observers.insert(
2113            (),
2114            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2115        );
2116        activate();
2117        subscription
2118    }
2119
2120    /// Register a callback to be invoked when the window is activated or deactivated.
2121    pub fn observe_window_activation(
2122        &mut self,
2123        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2124    ) -> Subscription {
2125        let view = self.view.downgrade();
2126        let (subscription, activate) = self.window.activation_observers.insert(
2127            (),
2128            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2129        );
2130        activate();
2131        subscription
2132    }
2133
2134    /// Registers a callback to be invoked when the window appearance changes.
2135    pub fn observe_window_appearance(
2136        &mut self,
2137        mut callback: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2138    ) -> Subscription {
2139        let view = self.view.downgrade();
2140        let (subscription, activate) = self.window.appearance_observers.insert(
2141            (),
2142            Box::new(move |cx| view.update(cx, |view, cx| callback(view, cx)).is_ok()),
2143        );
2144        activate();
2145        subscription
2146    }
2147
2148    /// Register a listener to be called when the given focus handle receives focus.
2149    /// Returns a subscription and persists until the subscription is dropped.
2150    pub fn on_focus(
2151        &mut self,
2152        handle: &FocusHandle,
2153        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2154    ) -> Subscription {
2155        let view = self.view.downgrade();
2156        let focus_id = handle.id;
2157        let (subscription, activate) =
2158            self.window.new_focus_listener(Box::new(move |event, cx| {
2159                view.update(cx, |view, cx| {
2160                    if event.previous_focus_path.last() != Some(&focus_id)
2161                        && event.current_focus_path.last() == Some(&focus_id)
2162                    {
2163                        listener(view, cx)
2164                    }
2165                })
2166                .is_ok()
2167            }));
2168        self.app.defer(|_| activate());
2169        subscription
2170    }
2171
2172    /// Register a listener to be called when the given focus handle or one of its descendants receives focus.
2173    /// Returns a subscription and persists until the subscription is dropped.
2174    pub fn on_focus_in(
2175        &mut self,
2176        handle: &FocusHandle,
2177        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2178    ) -> Subscription {
2179        let view = self.view.downgrade();
2180        let focus_id = handle.id;
2181        let (subscription, activate) =
2182            self.window.new_focus_listener(Box::new(move |event, cx| {
2183                view.update(cx, |view, cx| {
2184                    if !event.previous_focus_path.contains(&focus_id)
2185                        && event.current_focus_path.contains(&focus_id)
2186                    {
2187                        listener(view, cx)
2188                    }
2189                })
2190                .is_ok()
2191            }));
2192        self.app.defer(move |_| activate());
2193        subscription
2194    }
2195
2196    /// Register a listener to be called when the given focus handle loses focus.
2197    /// Returns a subscription and persists until the subscription is dropped.
2198    pub fn on_blur(
2199        &mut self,
2200        handle: &FocusHandle,
2201        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2202    ) -> Subscription {
2203        let view = self.view.downgrade();
2204        let focus_id = handle.id;
2205        let (subscription, activate) =
2206            self.window.new_focus_listener(Box::new(move |event, cx| {
2207                view.update(cx, |view, cx| {
2208                    if event.previous_focus_path.last() == Some(&focus_id)
2209                        && event.current_focus_path.last() != Some(&focus_id)
2210                    {
2211                        listener(view, cx)
2212                    }
2213                })
2214                .is_ok()
2215            }));
2216        self.app.defer(move |_| activate());
2217        subscription
2218    }
2219
2220    /// Register a listener to be called when nothing in the window has focus.
2221    /// This typically happens when the node that was focused is removed from the tree,
2222    /// and this callback lets you chose a default place to restore the users focus.
2223    /// Returns a subscription and persists until the subscription is dropped.
2224    pub fn on_focus_lost(
2225        &mut self,
2226        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2227    ) -> Subscription {
2228        let view = self.view.downgrade();
2229        let (subscription, activate) = self.window.focus_lost_listeners.insert(
2230            (),
2231            Box::new(move |cx| view.update(cx, |view, cx| listener(view, cx)).is_ok()),
2232        );
2233        activate();
2234        subscription
2235    }
2236
2237    /// Register a listener to be called when the given focus handle or one of its descendants loses focus.
2238    /// Returns a subscription and persists until the subscription is dropped.
2239    pub fn on_focus_out(
2240        &mut self,
2241        handle: &FocusHandle,
2242        mut listener: impl FnMut(&mut V, &mut ViewContext<V>) + 'static,
2243    ) -> Subscription {
2244        let view = self.view.downgrade();
2245        let focus_id = handle.id;
2246        let (subscription, activate) =
2247            self.window.new_focus_listener(Box::new(move |event, cx| {
2248                view.update(cx, |view, cx| {
2249                    if event.previous_focus_path.contains(&focus_id)
2250                        && !event.current_focus_path.contains(&focus_id)
2251                    {
2252                        listener(view, cx)
2253                    }
2254                })
2255                .is_ok()
2256            }));
2257        self.app.defer(move |_| activate());
2258        subscription
2259    }
2260
2261    /// Schedule a future to be run asynchronously.
2262    /// The given callback is invoked with a [`WeakView<V>`] to avoid leaking the view for a long-running process.
2263    /// It's also given an [`AsyncWindowContext`], which can be used to access the state of the view across await points.
2264    /// The returned future will be polled on the main thread.
2265    pub fn spawn<Fut, R>(
2266        &mut self,
2267        f: impl FnOnce(WeakView<V>, AsyncWindowContext) -> Fut,
2268    ) -> Task<R>
2269    where
2270        R: 'static,
2271        Fut: Future<Output = R> + 'static,
2272    {
2273        let view = self.view().downgrade();
2274        self.window_cx.spawn(|cx| f(view, cx))
2275    }
2276
2277    /// Updates the global state of the given type.
2278    pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
2279    where
2280        G: Global,
2281    {
2282        let mut global = self.app.lease_global::<G>();
2283        let result = f(&mut global, self);
2284        self.app.end_global_lease(global);
2285        result
2286    }
2287
2288    /// Register a callback to be invoked when the given global state changes.
2289    pub fn observe_global<G: Global>(
2290        &mut self,
2291        mut f: impl FnMut(&mut V, &mut ViewContext<'_, V>) + 'static,
2292    ) -> Subscription {
2293        let window_handle = self.window.handle;
2294        let view = self.view().downgrade();
2295        let (subscription, activate) = self.global_observers.insert(
2296            TypeId::of::<G>(),
2297            Box::new(move |cx| {
2298                window_handle
2299                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
2300                    .unwrap_or(false)
2301            }),
2302        );
2303        self.app.defer(move |_| activate());
2304        subscription
2305    }
2306
2307    /// Register a callback to be invoked when the given Action type is dispatched to the window.
2308    pub fn on_action(
2309        &mut self,
2310        action_type: TypeId,
2311        listener: impl Fn(&mut V, &dyn Any, DispatchPhase, &mut ViewContext<V>) + 'static,
2312    ) {
2313        let handle = self.view().clone();
2314        self.window_cx
2315            .on_action(action_type, move |action, phase, cx| {
2316                handle.update(cx, |view, cx| {
2317                    listener(view, action, phase, cx);
2318                })
2319            });
2320    }
2321
2322    /// Emit an event to be handled any other views that have subscribed via [ViewContext::subscribe].
2323    pub fn emit<Evt>(&mut self, event: Evt)
2324    where
2325        Evt: 'static,
2326        V: EventEmitter<Evt>,
2327    {
2328        let emitter = self.view.model.entity_id;
2329        self.app.push_effect(Effect::Emit {
2330            emitter,
2331            event_type: TypeId::of::<Evt>(),
2332            event: Box::new(event),
2333        });
2334    }
2335
2336    /// Move focus to the current view, assuming it implements [`FocusableView`].
2337    pub fn focus_self(&mut self)
2338    where
2339        V: FocusableView,
2340    {
2341        self.defer(|view, cx| view.focus_handle(cx).focus(cx))
2342    }
2343
2344    /// Convenience method for accessing view state in an event callback.
2345    ///
2346    /// Many GPUI callbacks take the form of `Fn(&E, &mut WindowContext)`,
2347    /// but it's often useful to be able to access view state in these
2348    /// callbacks. This method provides a convenient way to do so.
2349    pub fn listener<E>(
2350        &self,
2351        f: impl Fn(&mut V, &E, &mut ViewContext<V>) + 'static,
2352    ) -> impl Fn(&E, &mut WindowContext) + 'static {
2353        let view = self.view().downgrade();
2354        move |e: &E, cx: &mut WindowContext| {
2355            view.update(cx, |view, cx| f(view, e, cx)).ok();
2356        }
2357    }
2358}
2359
2360impl<V> Context for ViewContext<'_, V> {
2361    type Result<U> = U;
2362
2363    fn new_model<T: 'static>(
2364        &mut self,
2365        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
2366    ) -> Model<T> {
2367        self.window_cx.new_model(build_model)
2368    }
2369
2370    fn update_model<T: 'static, R>(
2371        &mut self,
2372        model: &Model<T>,
2373        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
2374    ) -> R {
2375        self.window_cx.update_model(model, update)
2376    }
2377
2378    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
2379    where
2380        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
2381    {
2382        self.window_cx.update_window(window, update)
2383    }
2384
2385    fn read_model<T, R>(
2386        &self,
2387        handle: &Model<T>,
2388        read: impl FnOnce(&T, &AppContext) -> R,
2389    ) -> Self::Result<R>
2390    where
2391        T: 'static,
2392    {
2393        self.window_cx.read_model(handle, read)
2394    }
2395
2396    fn read_window<T, R>(
2397        &self,
2398        window: &WindowHandle<T>,
2399        read: impl FnOnce(View<T>, &AppContext) -> R,
2400    ) -> Result<R>
2401    where
2402        T: 'static,
2403    {
2404        self.window_cx.read_window(window, read)
2405    }
2406}
2407
2408impl<V: 'static> VisualContext for ViewContext<'_, V> {
2409    fn new_view<W: Render + 'static>(
2410        &mut self,
2411        build_view_state: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2412    ) -> Self::Result<View<W>> {
2413        self.window_cx.new_view(build_view_state)
2414    }
2415
2416    fn update_view<V2: 'static, R>(
2417        &mut self,
2418        view: &View<V2>,
2419        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
2420    ) -> Self::Result<R> {
2421        self.window_cx.update_view(view, update)
2422    }
2423
2424    fn replace_root_view<W>(
2425        &mut self,
2426        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
2427    ) -> Self::Result<View<W>>
2428    where
2429        W: 'static + Render,
2430    {
2431        self.window_cx.replace_root_view(build_view)
2432    }
2433
2434    fn focus_view<W: FocusableView>(&mut self, view: &View<W>) -> Self::Result<()> {
2435        self.window_cx.focus_view(view)
2436    }
2437
2438    fn dismiss_view<W: ManagedView>(&mut self, view: &View<W>) -> Self::Result<()> {
2439        self.window_cx.dismiss_view(view)
2440    }
2441}
2442
2443impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
2444    type Target = WindowContext<'a>;
2445
2446    fn deref(&self) -> &Self::Target {
2447        &self.window_cx
2448    }
2449}
2450
2451impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
2452    fn deref_mut(&mut self) -> &mut Self::Target {
2453        &mut self.window_cx
2454    }
2455}
2456
2457// #[derive(Clone, Copy, Eq, PartialEq, Hash)]
2458slotmap::new_key_type! {
2459    /// A unique identifier for a window.
2460    pub struct WindowId;
2461}
2462
2463impl WindowId {
2464    /// Converts this window ID to a `u64`.
2465    pub fn as_u64(&self) -> u64 {
2466        self.0.as_ffi()
2467    }
2468}
2469
2470/// A handle to a window with a specific root view type.
2471/// Note that this does not keep the window alive on its own.
2472#[derive(Deref, DerefMut)]
2473pub struct WindowHandle<V> {
2474    #[deref]
2475    #[deref_mut]
2476    pub(crate) any_handle: AnyWindowHandle,
2477    state_type: PhantomData<V>,
2478}
2479
2480impl<V: 'static + Render> WindowHandle<V> {
2481    /// Creates a new handle from a window ID.
2482    /// This does not check if the root type of the window is `V`.
2483    pub fn new(id: WindowId) -> Self {
2484        WindowHandle {
2485            any_handle: AnyWindowHandle {
2486                id,
2487                state_type: TypeId::of::<V>(),
2488            },
2489            state_type: PhantomData,
2490        }
2491    }
2492
2493    /// Get the root view out of this window.
2494    ///
2495    /// This will fail if the window is closed or if the root view's type does not match `V`.
2496    pub fn root<C>(&self, cx: &mut C) -> Result<View<V>>
2497    where
2498        C: Context,
2499    {
2500        Flatten::flatten(cx.update_window(self.any_handle, |root_view, _| {
2501            root_view
2502                .downcast::<V>()
2503                .map_err(|_| anyhow!("the type of the window's root view has changed"))
2504        }))
2505    }
2506
2507    /// Updates the root view of this window.
2508    ///
2509    /// This will fail if the window has been closed or if the root view's type does not match
2510    pub fn update<C, R>(
2511        &self,
2512        cx: &mut C,
2513        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
2514    ) -> Result<R>
2515    where
2516        C: Context,
2517    {
2518        cx.update_window(self.any_handle, |root_view, cx| {
2519            let view = root_view
2520                .downcast::<V>()
2521                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2522            Ok(cx.update_view(&view, update))
2523        })?
2524    }
2525
2526    /// Read the root view out of this window.
2527    ///
2528    /// This will fail if the window is closed or if the root view's type does not match `V`.
2529    pub fn read<'a>(&self, cx: &'a AppContext) -> Result<&'a V> {
2530        let x = cx
2531            .windows
2532            .get(self.id)
2533            .and_then(|window| {
2534                window
2535                    .as_ref()
2536                    .and_then(|window| window.root_view.clone())
2537                    .map(|root_view| root_view.downcast::<V>())
2538            })
2539            .ok_or_else(|| anyhow!("window not found"))?
2540            .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
2541
2542        Ok(x.read(cx))
2543    }
2544
2545    /// Read the root view out of this window, with a callback
2546    ///
2547    /// This will fail if the window is closed or if the root view's type does not match `V`.
2548    pub fn read_with<C, R>(&self, cx: &C, read_with: impl FnOnce(&V, &AppContext) -> R) -> Result<R>
2549    where
2550        C: Context,
2551    {
2552        cx.read_window(self, |root_view, cx| read_with(root_view.read(cx), cx))
2553    }
2554
2555    /// Read the root view pointer off of this window.
2556    ///
2557    /// This will fail if the window is closed or if the root view's type does not match `V`.
2558    pub fn root_view<C>(&self, cx: &C) -> Result<View<V>>
2559    where
2560        C: Context,
2561    {
2562        cx.read_window(self, |root_view, _cx| root_view.clone())
2563    }
2564
2565    /// Check if this window is 'active'.
2566    ///
2567    /// Will return `None` if the window is closed or currently
2568    /// borrowed.
2569    pub fn is_active(&self, cx: &mut AppContext) -> Option<bool> {
2570        cx.update_window(self.any_handle, |_, cx| cx.is_window_active())
2571            .ok()
2572    }
2573}
2574
2575impl<V> Copy for WindowHandle<V> {}
2576
2577impl<V> Clone for WindowHandle<V> {
2578    fn clone(&self) -> Self {
2579        *self
2580    }
2581}
2582
2583impl<V> PartialEq for WindowHandle<V> {
2584    fn eq(&self, other: &Self) -> bool {
2585        self.any_handle == other.any_handle
2586    }
2587}
2588
2589impl<V> Eq for WindowHandle<V> {}
2590
2591impl<V> Hash for WindowHandle<V> {
2592    fn hash<H: Hasher>(&self, state: &mut H) {
2593        self.any_handle.hash(state);
2594    }
2595}
2596
2597impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle {
2598    fn from(val: WindowHandle<V>) -> Self {
2599        val.any_handle
2600    }
2601}
2602
2603/// A handle to a window with any root view type, which can be downcast to a window with a specific root view type.
2604#[derive(Copy, Clone, PartialEq, Eq, Hash)]
2605pub struct AnyWindowHandle {
2606    pub(crate) id: WindowId,
2607    state_type: TypeId,
2608}
2609
2610impl AnyWindowHandle {
2611    /// Get the ID of this window.
2612    pub fn window_id(&self) -> WindowId {
2613        self.id
2614    }
2615
2616    /// Attempt to convert this handle to a window handle with a specific root view type.
2617    /// If the types do not match, this will return `None`.
2618    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
2619        if TypeId::of::<T>() == self.state_type {
2620            Some(WindowHandle {
2621                any_handle: *self,
2622                state_type: PhantomData,
2623            })
2624        } else {
2625            None
2626        }
2627    }
2628
2629    /// Updates the state of the root view of this window.
2630    ///
2631    /// This will fail if the window has been closed.
2632    pub fn update<C, R>(
2633        self,
2634        cx: &mut C,
2635        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
2636    ) -> Result<R>
2637    where
2638        C: Context,
2639    {
2640        cx.update_window(self, update)
2641    }
2642
2643    /// Read the state of the root view of this window.
2644    ///
2645    /// This will fail if the window has been closed.
2646    pub fn read<T, C, R>(self, cx: &C, read: impl FnOnce(View<T>, &AppContext) -> R) -> Result<R>
2647    where
2648        C: Context,
2649        T: 'static,
2650    {
2651        let view = self
2652            .downcast::<T>()
2653            .context("the type of the window's root view has changed")?;
2654
2655        cx.read_window(&view, read)
2656    }
2657}
2658
2659/// An identifier for an [`Element`](crate::Element).
2660///
2661/// Can be constructed with a string, a number, or both, as well
2662/// as other internal representations.
2663#[derive(Clone, Debug, Eq, PartialEq, Hash)]
2664pub enum ElementId {
2665    /// The ID of a View element
2666    View(EntityId),
2667    /// An integer ID.
2668    Integer(usize),
2669    /// A string based ID.
2670    Name(SharedString),
2671    /// An ID that's equated with a focus handle.
2672    FocusHandle(FocusId),
2673    /// A combination of a name and an integer.
2674    NamedInteger(SharedString, usize),
2675}
2676
2677impl Display for ElementId {
2678    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
2679        match self {
2680            ElementId::View(entity_id) => write!(f, "view-{}", entity_id)?,
2681            ElementId::Integer(ix) => write!(f, "{}", ix)?,
2682            ElementId::Name(name) => write!(f, "{}", name)?,
2683            ElementId::FocusHandle(_) => write!(f, "FocusHandle")?,
2684            ElementId::NamedInteger(s, i) => write!(f, "{}-{}", s, i)?,
2685        }
2686
2687        Ok(())
2688    }
2689}
2690
2691impl ElementId {
2692    pub(crate) fn from_entity_id(entity_id: EntityId) -> Self {
2693        ElementId::View(entity_id)
2694    }
2695}
2696
2697impl TryInto<SharedString> for ElementId {
2698    type Error = anyhow::Error;
2699
2700    fn try_into(self) -> anyhow::Result<SharedString> {
2701        if let ElementId::Name(name) = self {
2702            Ok(name)
2703        } else {
2704            Err(anyhow!("element id is not string"))
2705        }
2706    }
2707}
2708
2709impl From<usize> for ElementId {
2710    fn from(id: usize) -> Self {
2711        ElementId::Integer(id)
2712    }
2713}
2714
2715impl From<i32> for ElementId {
2716    fn from(id: i32) -> Self {
2717        Self::Integer(id as usize)
2718    }
2719}
2720
2721impl From<SharedString> for ElementId {
2722    fn from(name: SharedString) -> Self {
2723        ElementId::Name(name)
2724    }
2725}
2726
2727impl From<&'static str> for ElementId {
2728    fn from(name: &'static str) -> Self {
2729        ElementId::Name(name.into())
2730    }
2731}
2732
2733impl<'a> From<&'a FocusHandle> for ElementId {
2734    fn from(handle: &'a FocusHandle) -> Self {
2735        ElementId::FocusHandle(handle.id)
2736    }
2737}
2738
2739impl From<(&'static str, EntityId)> for ElementId {
2740    fn from((name, id): (&'static str, EntityId)) -> Self {
2741        ElementId::NamedInteger(name.into(), id.as_u64() as usize)
2742    }
2743}
2744
2745impl From<(&'static str, usize)> for ElementId {
2746    fn from((name, id): (&'static str, usize)) -> Self {
2747        ElementId::NamedInteger(name.into(), id)
2748    }
2749}
2750
2751impl From<(&'static str, u64)> for ElementId {
2752    fn from((name, id): (&'static str, u64)) -> Self {
2753        ElementId::NamedInteger(name.into(), id as usize)
2754    }
2755}
2756
2757/// A rectangle to be rendered in the window at the given position and size.
2758/// Passed as an argument [`ElementContext::paint_quad`].
2759#[derive(Clone)]
2760pub struct PaintQuad {
2761    bounds: Bounds<Pixels>,
2762    corner_radii: Corners<Pixels>,
2763    background: Hsla,
2764    border_widths: Edges<Pixels>,
2765    border_color: Hsla,
2766}
2767
2768impl PaintQuad {
2769    /// Sets the corner radii of the quad.
2770    pub fn corner_radii(self, corner_radii: impl Into<Corners<Pixels>>) -> Self {
2771        PaintQuad {
2772            corner_radii: corner_radii.into(),
2773            ..self
2774        }
2775    }
2776
2777    /// Sets the border widths of the quad.
2778    pub fn border_widths(self, border_widths: impl Into<Edges<Pixels>>) -> Self {
2779        PaintQuad {
2780            border_widths: border_widths.into(),
2781            ..self
2782        }
2783    }
2784
2785    /// Sets the border color of the quad.
2786    pub fn border_color(self, border_color: impl Into<Hsla>) -> Self {
2787        PaintQuad {
2788            border_color: border_color.into(),
2789            ..self
2790        }
2791    }
2792
2793    /// Sets the background color of the quad.
2794    pub fn background(self, background: impl Into<Hsla>) -> Self {
2795        PaintQuad {
2796            background: background.into(),
2797            ..self
2798        }
2799    }
2800}
2801
2802/// Creates a quad with the given parameters.
2803pub fn quad(
2804    bounds: Bounds<Pixels>,
2805    corner_radii: impl Into<Corners<Pixels>>,
2806    background: impl Into<Hsla>,
2807    border_widths: impl Into<Edges<Pixels>>,
2808    border_color: impl Into<Hsla>,
2809) -> PaintQuad {
2810    PaintQuad {
2811        bounds,
2812        corner_radii: corner_radii.into(),
2813        background: background.into(),
2814        border_widths: border_widths.into(),
2815        border_color: border_color.into(),
2816    }
2817}
2818
2819/// Creates a filled quad with the given bounds and background color.
2820pub fn fill(bounds: impl Into<Bounds<Pixels>>, background: impl Into<Hsla>) -> PaintQuad {
2821    PaintQuad {
2822        bounds: bounds.into(),
2823        corner_radii: (0.).into(),
2824        background: background.into(),
2825        border_widths: (0.).into(),
2826        border_color: transparent_black(),
2827    }
2828}
2829
2830/// Creates a rectangle outline with the given bounds, border color, and a 1px border width
2831pub fn outline(bounds: impl Into<Bounds<Pixels>>, border_color: impl Into<Hsla>) -> PaintQuad {
2832    PaintQuad {
2833        bounds: bounds.into(),
2834        corner_radii: (0.).into(),
2835        background: transparent_black(),
2836        border_widths: (1.).into(),
2837        border_color: border_color.into(),
2838    }
2839}