div.rs

   1//! Div is the central, reusable element that most GPUI trees will be built from.
   2//! It functions as a container for other elements, and provides a number of
   3//! useful features for laying out and styling its children as well as binding
   4//! mouse events and action handlers. It is meant to be similar to the HTML `<div>`
   5//! element, but for GPUI.
   6//!
   7//! # Build your own div
   8//!
   9//! GPUI does not directly provide APIs for stateful, multi step events like `click`
  10//! and `drag`. We want GPUI users to be able to build their own abstractions for
  11//! their own needs. However, as a UI framework, we're also obliged to provide some
  12//! building blocks to make the process of building your own elements easier.
  13//! For this we have the [`Interactivity`] and the [`StyleRefinement`] structs, as well
  14//! as several associated traits. Together, these provide the full suite of Dom-like events
  15//! and Tailwind-like styling that you can use to build your own custom elements. Div is
  16//! constructed by combining these two systems into an all-in-one element.
  17
  18use crate::{
  19    Action, AnyDrag, AnyElement, AnyTooltip, AnyView, App, Bounds, ClickEvent, DispatchPhase,
  20    Element, ElementId, Entity, FocusHandle, Global, GlobalElementId, Hitbox, HitboxBehavior,
  21    HitboxId, InspectorElementId, IntoElement, IsZero, KeyContext, KeyDownEvent, KeyUpEvent,
  22    KeyboardButton, KeyboardClickEvent, LayoutId, ModifiersChangedEvent, MouseButton,
  23    MouseClickEvent, MouseDownEvent, MouseMoveEvent, MouseUpEvent, Overflow, ParentElement, Pixels,
  24    Point, Render, ScrollWheelEvent, SharedString, Size, Style, StyleRefinement, Styled, Task,
  25    TooltipId, Visibility, Window, WindowControlArea, point, px, size,
  26    taffy::{CONTAINER_LAYOUT_ID_TO_DEBUG, LAYOUT_ID_TO_DEBUG},
  27};
  28use collections::HashMap;
  29use refineable::Refineable;
  30use smallvec::SmallVec;
  31use std::{
  32    any::{Any, TypeId},
  33    cell::RefCell,
  34    cmp::Ordering,
  35    fmt::Debug,
  36    marker::PhantomData,
  37    mem,
  38    rc::Rc,
  39    sync::Arc,
  40    time::Duration,
  41};
  42use util::ResultExt;
  43
  44use super::ImageCacheProvider;
  45
  46const DRAG_THRESHOLD: f64 = 2.;
  47const TOOLTIP_SHOW_DELAY: Duration = Duration::from_millis(500);
  48const HOVERABLE_TOOLTIP_HIDE_DELAY: Duration = Duration::from_millis(500);
  49
  50/// The styling information for a given group.
  51pub struct GroupStyle {
  52    /// The identifier for this group.
  53    pub group: SharedString,
  54
  55    /// The specific style refinement that this group would apply
  56    /// to its children.
  57    pub style: Box<StyleRefinement>,
  58}
  59
  60/// An event for when a drag is moving over this element, with the given state type.
  61pub struct DragMoveEvent<T> {
  62    /// The mouse move event that triggered this drag move event.
  63    pub event: MouseMoveEvent,
  64
  65    /// The bounds of this element.
  66    pub bounds: Bounds<Pixels>,
  67    drag: PhantomData<T>,
  68    dragged_item: Arc<dyn Any>,
  69}
  70
  71impl<T: 'static> DragMoveEvent<T> {
  72    /// Returns the drag state for this event.
  73    pub fn drag<'b>(&self, cx: &'b App) -> &'b T {
  74        cx.active_drag
  75            .as_ref()
  76            .and_then(|drag| drag.value.downcast_ref::<T>())
  77            .expect("DragMoveEvent is only valid when the stored active drag is of the same type.")
  78    }
  79
  80    /// An item that is about to be dropped.
  81    pub fn dragged_item(&self) -> &dyn Any {
  82        self.dragged_item.as_ref()
  83    }
  84}
  85
  86impl Interactivity {
  87    /// Create an `Interactivity`, capturing the caller location in debug mode.
  88    #[cfg(any(feature = "inspector", debug_assertions))]
  89    #[track_caller]
  90    pub fn new() -> Interactivity {
  91        Interactivity {
  92            source_location: Some(core::panic::Location::caller()),
  93            ..Default::default()
  94        }
  95    }
  96
  97    /// Create an `Interactivity`, capturing the caller location in debug mode.
  98    #[cfg(not(any(feature = "inspector", debug_assertions)))]
  99    pub fn new() -> Interactivity {
 100        Interactivity::default()
 101    }
 102
 103    /// Gets the source location of construction. Returns `None` when not in debug mode.
 104    pub fn source_location(&self) -> Option<&'static std::panic::Location<'static>> {
 105        #[cfg(any(feature = "inspector", debug_assertions))]
 106        {
 107            self.source_location
 108        }
 109
 110        #[cfg(not(any(feature = "inspector", debug_assertions)))]
 111        {
 112            None
 113        }
 114    }
 115
 116    /// Bind the given callback to the mouse down event for the given mouse button, during the bubble phase
 117    /// The imperative API equivalent of [`InteractiveElement::on_mouse_down`]
 118    ///
 119    /// See [`Context::listener`](crate::Context::listener) to get access to the view state from this callback.
 120    pub fn on_mouse_down(
 121        &mut self,
 122        button: MouseButton,
 123        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 124    ) {
 125        self.mouse_down_listeners
 126            .push(Box::new(move |event, phase, hitbox, window, cx| {
 127                if phase == DispatchPhase::Bubble
 128                    && event.button == button
 129                    && hitbox.is_hovered(window)
 130                {
 131                    (listener)(event, window, cx)
 132                }
 133            }));
 134    }
 135
 136    /// Bind the given callback to the mouse down event for any button, during the capture phase
 137    /// The imperative API equivalent of [`InteractiveElement::capture_any_mouse_down`]
 138    ///
 139    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 140    pub fn capture_any_mouse_down(
 141        &mut self,
 142        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 143    ) {
 144        self.mouse_down_listeners
 145            .push(Box::new(move |event, phase, hitbox, window, cx| {
 146                if phase == DispatchPhase::Capture && hitbox.is_hovered(window) {
 147                    (listener)(event, window, cx)
 148                }
 149            }));
 150    }
 151
 152    /// Bind the given callback to the mouse down event for any button, during the bubble phase
 153    /// the imperative API equivalent to [`InteractiveElement::on_any_mouse_down`]
 154    ///
 155    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 156    pub fn on_any_mouse_down(
 157        &mut self,
 158        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 159    ) {
 160        self.mouse_down_listeners
 161            .push(Box::new(move |event, phase, hitbox, window, cx| {
 162                if phase == DispatchPhase::Bubble && hitbox.is_hovered(window) {
 163                    (listener)(event, window, cx)
 164                }
 165            }));
 166    }
 167
 168    /// Bind the given callback to the mouse up event for the given button, during the bubble phase
 169    /// the imperative API equivalent to [`InteractiveElement::on_mouse_up`]
 170    ///
 171    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 172    pub fn on_mouse_up(
 173        &mut self,
 174        button: MouseButton,
 175        listener: impl Fn(&MouseUpEvent, &mut Window, &mut App) + 'static,
 176    ) {
 177        self.mouse_up_listeners
 178            .push(Box::new(move |event, phase, hitbox, window, cx| {
 179                if phase == DispatchPhase::Bubble
 180                    && event.button == button
 181                    && hitbox.is_hovered(window)
 182                {
 183                    (listener)(event, window, cx)
 184                }
 185            }));
 186    }
 187
 188    /// Bind the given callback to the mouse up event for any button, during the capture phase
 189    /// the imperative API equivalent to [`InteractiveElement::capture_any_mouse_up`]
 190    ///
 191    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 192    pub fn capture_any_mouse_up(
 193        &mut self,
 194        listener: impl Fn(&MouseUpEvent, &mut Window, &mut App) + 'static,
 195    ) {
 196        self.mouse_up_listeners
 197            .push(Box::new(move |event, phase, hitbox, window, cx| {
 198                if phase == DispatchPhase::Capture && hitbox.is_hovered(window) {
 199                    (listener)(event, window, cx)
 200                }
 201            }));
 202    }
 203
 204    /// Bind the given callback to the mouse up event for any button, during the bubble phase
 205    /// the imperative API equivalent to [`Interactivity::on_any_mouse_up`]
 206    ///
 207    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 208    pub fn on_any_mouse_up(
 209        &mut self,
 210        listener: impl Fn(&MouseUpEvent, &mut Window, &mut App) + 'static,
 211    ) {
 212        self.mouse_up_listeners
 213            .push(Box::new(move |event, phase, hitbox, window, cx| {
 214                if phase == DispatchPhase::Bubble && hitbox.is_hovered(window) {
 215                    (listener)(event, window, cx)
 216                }
 217            }));
 218    }
 219
 220    /// Bind the given callback to the mouse down event, on any button, during the capture phase,
 221    /// when the mouse is outside of the bounds of this element.
 222    /// The imperative API equivalent to [`InteractiveElement::on_mouse_down_out`]
 223    ///
 224    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 225    pub fn on_mouse_down_out(
 226        &mut self,
 227        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 228    ) {
 229        self.mouse_down_listeners
 230            .push(Box::new(move |event, phase, hitbox, window, cx| {
 231                if phase == DispatchPhase::Capture && !hitbox.contains(&window.mouse_position()) {
 232                    (listener)(event, window, cx)
 233                }
 234            }));
 235    }
 236
 237    /// Bind the given callback to the mouse up event, for the given button, during the capture phase,
 238    /// when the mouse is outside of the bounds of this element.
 239    /// The imperative API equivalent to [`InteractiveElement::on_mouse_up_out`]
 240    ///
 241    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 242    pub fn on_mouse_up_out(
 243        &mut self,
 244        button: MouseButton,
 245        listener: impl Fn(&MouseUpEvent, &mut Window, &mut App) + 'static,
 246    ) {
 247        self.mouse_up_listeners
 248            .push(Box::new(move |event, phase, hitbox, window, cx| {
 249                if phase == DispatchPhase::Capture
 250                    && event.button == button
 251                    && !hitbox.is_hovered(window)
 252                {
 253                    (listener)(event, window, cx);
 254                }
 255            }));
 256    }
 257
 258    /// Bind the given callback to the mouse move event, during the bubble phase
 259    /// The imperative API equivalent to [`InteractiveElement::on_mouse_move`]
 260    ///
 261    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 262    pub fn on_mouse_move(
 263        &mut self,
 264        listener: impl Fn(&MouseMoveEvent, &mut Window, &mut App) + 'static,
 265    ) {
 266        self.mouse_move_listeners
 267            .push(Box::new(move |event, phase, hitbox, window, cx| {
 268                if phase == DispatchPhase::Bubble && hitbox.is_hovered(window) {
 269                    (listener)(event, window, cx);
 270                }
 271            }));
 272    }
 273
 274    /// Bind the given callback to the mouse drag event of the given type. Note that this
 275    /// will be called for all move events, inside or outside of this element, as long as the
 276    /// drag was started with this element under the mouse. Useful for implementing draggable
 277    /// UIs that don't conform to a drag and drop style interaction, like resizing.
 278    /// The imperative API equivalent to [`InteractiveElement::on_drag_move`]
 279    ///
 280    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 281    pub fn on_drag_move<T>(
 282        &mut self,
 283        listener: impl Fn(&DragMoveEvent<T>, &mut Window, &mut App) + 'static,
 284    ) where
 285        T: 'static,
 286    {
 287        self.mouse_move_listeners
 288            .push(Box::new(move |event, phase, hitbox, window, cx| {
 289                if phase == DispatchPhase::Capture {
 290                    if let Some(drag) = &cx.active_drag {
 291                        if drag.value.as_ref().type_id() == TypeId::of::<T>() {
 292                            (listener)(
 293                                &DragMoveEvent {
 294                                    event: event.clone(),
 295                                    bounds: hitbox.bounds,
 296                                    drag: PhantomData,
 297                                    dragged_item: Arc::clone(&drag.value),
 298                                },
 299                                window,
 300                                cx,
 301                            );
 302                        }
 303                    }
 304                }
 305            }));
 306    }
 307
 308    /// Bind the given callback to scroll wheel events during the bubble phase
 309    /// The imperative API equivalent to [`InteractiveElement::on_scroll_wheel`]
 310    ///
 311    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 312    pub fn on_scroll_wheel(
 313        &mut self,
 314        listener: impl Fn(&ScrollWheelEvent, &mut Window, &mut App) + 'static,
 315    ) {
 316        self.scroll_wheel_listeners
 317            .push(Box::new(move |event, phase, hitbox, window, cx| {
 318                if phase == DispatchPhase::Bubble && hitbox.should_handle_scroll(window) {
 319                    (listener)(event, window, cx);
 320                }
 321            }));
 322    }
 323
 324    /// Bind the given callback to an action dispatch during the capture phase
 325    /// The imperative API equivalent to [`InteractiveElement::capture_action`]
 326    ///
 327    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 328    pub fn capture_action<A: Action>(
 329        &mut self,
 330        listener: impl Fn(&A, &mut Window, &mut App) + 'static,
 331    ) {
 332        self.action_listeners.push((
 333            TypeId::of::<A>(),
 334            Box::new(move |action, phase, window, cx| {
 335                let action = action.downcast_ref().unwrap();
 336                if phase == DispatchPhase::Capture {
 337                    (listener)(action, window, cx)
 338                } else {
 339                    cx.propagate();
 340                }
 341            }),
 342        ));
 343    }
 344
 345    /// Bind the given callback to an action dispatch during the bubble phase
 346    /// The imperative API equivalent to [`InteractiveElement::on_action`]
 347    ///
 348    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 349    pub fn on_action<A: Action>(&mut self, listener: impl Fn(&A, &mut Window, &mut App) + 'static) {
 350        self.action_listeners.push((
 351            TypeId::of::<A>(),
 352            Box::new(move |action, phase, window, cx| {
 353                let action = action.downcast_ref().unwrap();
 354                if phase == DispatchPhase::Bubble {
 355                    (listener)(action, window, cx)
 356                }
 357            }),
 358        ));
 359    }
 360
 361    /// Bind the given callback to an action dispatch, based on a dynamic action parameter
 362    /// instead of a type parameter. Useful for component libraries that want to expose
 363    /// action bindings to their users.
 364    /// The imperative API equivalent to [`InteractiveElement::on_boxed_action`]
 365    ///
 366    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 367    pub fn on_boxed_action(
 368        &mut self,
 369        action: &dyn Action,
 370        listener: impl Fn(&dyn Action, &mut Window, &mut App) + 'static,
 371    ) {
 372        let action = action.boxed_clone();
 373        self.action_listeners.push((
 374            (*action).type_id(),
 375            Box::new(move |_, phase, window, cx| {
 376                if phase == DispatchPhase::Bubble {
 377                    (listener)(&*action, window, cx)
 378                }
 379            }),
 380        ));
 381    }
 382
 383    /// Bind the given callback to key down events during the bubble phase
 384    /// The imperative API equivalent to [`InteractiveElement::on_key_down`]
 385    ///
 386    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 387    pub fn on_key_down(
 388        &mut self,
 389        listener: impl Fn(&KeyDownEvent, &mut Window, &mut App) + 'static,
 390    ) {
 391        self.key_down_listeners
 392            .push(Box::new(move |event, phase, window, cx| {
 393                if phase == DispatchPhase::Bubble {
 394                    (listener)(event, window, cx)
 395                }
 396            }));
 397    }
 398
 399    /// Bind the given callback to key down events during the capture phase
 400    /// The imperative API equivalent to [`InteractiveElement::capture_key_down`]
 401    ///
 402    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 403    pub fn capture_key_down(
 404        &mut self,
 405        listener: impl Fn(&KeyDownEvent, &mut Window, &mut App) + 'static,
 406    ) {
 407        self.key_down_listeners
 408            .push(Box::new(move |event, phase, window, cx| {
 409                if phase == DispatchPhase::Capture {
 410                    listener(event, window, cx)
 411                }
 412            }));
 413    }
 414
 415    /// Bind the given callback to key up events during the bubble phase
 416    /// The imperative API equivalent to [`InteractiveElement::on_key_up`]
 417    ///
 418    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 419    pub fn on_key_up(&mut self, listener: impl Fn(&KeyUpEvent, &mut Window, &mut App) + 'static) {
 420        self.key_up_listeners
 421            .push(Box::new(move |event, phase, window, cx| {
 422                if phase == DispatchPhase::Bubble {
 423                    listener(event, window, cx)
 424                }
 425            }));
 426    }
 427
 428    /// Bind the given callback to key up events during the capture phase
 429    /// The imperative API equivalent to [`InteractiveElement::on_key_up`]
 430    ///
 431    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 432    pub fn capture_key_up(
 433        &mut self,
 434        listener: impl Fn(&KeyUpEvent, &mut Window, &mut App) + 'static,
 435    ) {
 436        self.key_up_listeners
 437            .push(Box::new(move |event, phase, window, cx| {
 438                if phase == DispatchPhase::Capture {
 439                    listener(event, window, cx)
 440                }
 441            }));
 442    }
 443
 444    /// Bind the given callback to modifiers changing events.
 445    /// The imperative API equivalent to [`InteractiveElement::on_modifiers_changed`]
 446    ///
 447    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 448    pub fn on_modifiers_changed(
 449        &mut self,
 450        listener: impl Fn(&ModifiersChangedEvent, &mut Window, &mut App) + 'static,
 451    ) {
 452        self.modifiers_changed_listeners
 453            .push(Box::new(move |event, window, cx| {
 454                listener(event, window, cx)
 455            }));
 456    }
 457
 458    /// Bind the given callback to drop events of the given type, whether or not the drag started on this element
 459    /// The imperative API equivalent to [`InteractiveElement::on_drop`]
 460    ///
 461    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 462    pub fn on_drop<T: 'static>(&mut self, listener: impl Fn(&T, &mut Window, &mut App) + 'static) {
 463        self.drop_listeners.push((
 464            TypeId::of::<T>(),
 465            Box::new(move |dragged_value, window, cx| {
 466                listener(dragged_value.downcast_ref().unwrap(), window, cx);
 467            }),
 468        ));
 469    }
 470
 471    /// Use the given predicate to determine whether or not a drop event should be dispatched to this element
 472    /// The imperative API equivalent to [`InteractiveElement::can_drop`]
 473    pub fn can_drop(
 474        &mut self,
 475        predicate: impl Fn(&dyn Any, &mut Window, &mut App) -> bool + 'static,
 476    ) {
 477        self.can_drop_predicate = Some(Box::new(predicate));
 478    }
 479
 480    /// Bind the given callback to click events of this element
 481    /// The imperative API equivalent to [`StatefulInteractiveElement::on_click`]
 482    ///
 483    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 484    pub fn on_click(&mut self, listener: impl Fn(&ClickEvent, &mut Window, &mut App) + 'static)
 485    where
 486        Self: Sized,
 487    {
 488        self.click_listeners.push(Rc::new(move |event, window, cx| {
 489            listener(event, window, cx)
 490        }));
 491    }
 492
 493    /// On drag initiation, this callback will be used to create a new view to render the dragged value for a
 494    /// drag and drop operation. This API should also be used as the equivalent of 'on drag start' with
 495    /// the [`Self::on_drag_move`] API
 496    /// The imperative API equivalent to [`StatefulInteractiveElement::on_drag`]
 497    ///
 498    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 499    pub fn on_drag<T, W>(
 500        &mut self,
 501        value: T,
 502        constructor: impl Fn(&T, Point<Pixels>, &mut Window, &mut App) -> Entity<W> + 'static,
 503    ) where
 504        Self: Sized,
 505        T: 'static,
 506        W: 'static + Render,
 507    {
 508        debug_assert!(
 509            self.drag_listener.is_none(),
 510            "calling on_drag more than once on the same element is not supported"
 511        );
 512        self.drag_listener = Some((
 513            Arc::new(value),
 514            Box::new(move |value, offset, window, cx| {
 515                constructor(value.downcast_ref().unwrap(), offset, window, cx).into()
 516            }),
 517        ));
 518    }
 519
 520    /// Bind the given callback on the hover start and end events of this element. Note that the boolean
 521    /// passed to the callback is true when the hover starts and false when it ends.
 522    /// The imperative API equivalent to [`StatefulInteractiveElement::on_hover`]
 523    ///
 524    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 525    pub fn on_hover(&mut self, listener: impl Fn(&bool, &mut Window, &mut App) + 'static)
 526    where
 527        Self: Sized,
 528    {
 529        debug_assert!(
 530            self.hover_listener.is_none(),
 531            "calling on_hover more than once on the same element is not supported"
 532        );
 533        self.hover_listener = Some(Box::new(listener));
 534    }
 535
 536    /// Use the given callback to construct a new tooltip view when the mouse hovers over this element.
 537    /// The imperative API equivalent to [`InteractiveElement::tooltip`]
 538    pub fn tooltip(&mut self, build_tooltip: impl Fn(&mut Window, &mut App) -> AnyView + 'static)
 539    where
 540        Self: Sized,
 541    {
 542        debug_assert!(
 543            self.tooltip_builder.is_none(),
 544            "calling tooltip more than once on the same element is not supported"
 545        );
 546        self.tooltip_builder = Some(TooltipBuilder {
 547            build: Rc::new(build_tooltip),
 548            hoverable: false,
 549        });
 550    }
 551
 552    /// Use the given callback to construct a new tooltip view when the mouse hovers over this element.
 553    /// The tooltip itself is also hoverable and won't disappear when the user moves the mouse into
 554    /// the tooltip. The imperative API equivalent to [`InteractiveElement::hoverable_tooltip`]
 555    pub fn hoverable_tooltip(
 556        &mut self,
 557        build_tooltip: impl Fn(&mut Window, &mut App) -> AnyView + 'static,
 558    ) where
 559        Self: Sized,
 560    {
 561        debug_assert!(
 562            self.tooltip_builder.is_none(),
 563            "calling tooltip more than once on the same element is not supported"
 564        );
 565        self.tooltip_builder = Some(TooltipBuilder {
 566            build: Rc::new(build_tooltip),
 567            hoverable: true,
 568        });
 569    }
 570
 571    /// Block the mouse from all interactions with elements behind this element's hitbox. Typically
 572    /// `block_mouse_except_scroll` should be preferred.
 573    ///
 574    /// The imperative API equivalent to [`InteractiveElement::occlude`]
 575    pub fn occlude_mouse(&mut self) {
 576        self.hitbox_behavior = HitboxBehavior::BlockMouse;
 577    }
 578
 579    /// Set the bounds of this element as a window control area for the platform window.
 580    /// The imperative API equivalent to [`InteractiveElement::window_control_area`]
 581    pub fn window_control_area(&mut self, area: WindowControlArea) {
 582        self.window_control = Some(area);
 583    }
 584
 585    /// Block non-scroll mouse interactions with elements behind this element's hitbox. See
 586    /// [`Hitbox::is_hovered`] for details.
 587    ///
 588    /// The imperative API equivalent to [`InteractiveElement::block_mouse_except_scroll`]
 589    pub fn block_mouse_except_scroll(&mut self) {
 590        self.hitbox_behavior = HitboxBehavior::BlockMouseExceptScroll;
 591    }
 592}
 593
 594/// A trait for elements that want to use the standard GPUI event handlers that don't
 595/// require any state.
 596pub trait InteractiveElement: Sized {
 597    /// Retrieve the interactivity state associated with this element
 598    fn interactivity(&mut self) -> &mut Interactivity;
 599
 600    /// Assign this element to a group of elements that can be styled together
 601    fn group(mut self, group: impl Into<SharedString>) -> Self {
 602        self.interactivity().group = Some(group.into());
 603        self
 604    }
 605
 606    /// Assign this element an ID, so that it can be used with interactivity
 607    fn id(mut self, id: impl Into<ElementId>) -> Stateful<Self> {
 608        self.interactivity().element_id = Some(id.into());
 609
 610        Stateful { element: self }
 611    }
 612
 613    /// Track the focus state of the given focus handle on this element.
 614    /// If the focus handle is focused by the application, this element will
 615    /// apply its focused styles.
 616    fn track_focus(mut self, focus_handle: &FocusHandle) -> Self {
 617        self.interactivity().focusable = true;
 618        self.interactivity().tracked_focus_handle = Some(focus_handle.clone());
 619        self
 620    }
 621
 622    /// Set index of the tab stop order.
 623    fn tab_index(mut self, index: isize) -> Self {
 624        self.interactivity().focusable = true;
 625        self.interactivity().tab_index = Some(index);
 626        self
 627    }
 628
 629    /// Set the keymap context for this element. This will be used to determine
 630    /// which action to dispatch from the keymap.
 631    fn key_context<C, E>(mut self, key_context: C) -> Self
 632    where
 633        C: TryInto<KeyContext, Error = E>,
 634        E: Debug,
 635    {
 636        if let Some(key_context) = key_context.try_into().log_err() {
 637            self.interactivity().key_context = Some(key_context);
 638        }
 639        self
 640    }
 641
 642    /// Apply the given style to this element when the mouse hovers over it
 643    fn hover(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self {
 644        debug_assert!(
 645            self.interactivity().hover_style.is_none(),
 646            "hover style already set"
 647        );
 648        self.interactivity().hover_style = Some(Box::new(f(StyleRefinement::default())));
 649        self
 650    }
 651
 652    /// Apply the given style to this element when the mouse hovers over a group member
 653    fn group_hover(
 654        mut self,
 655        group_name: impl Into<SharedString>,
 656        f: impl FnOnce(StyleRefinement) -> StyleRefinement,
 657    ) -> Self {
 658        self.interactivity().group_hover_style = Some(GroupStyle {
 659            group: group_name.into(),
 660            style: Box::new(f(StyleRefinement::default())),
 661        });
 662        self
 663    }
 664
 665    /// Bind the given callback to the mouse down event for the given mouse button,
 666    /// the fluent API equivalent to [`Interactivity::on_mouse_down`]
 667    ///
 668    /// See [`Context::listener`](crate::Context::listener) to get access to the view state from this callback.
 669    fn on_mouse_down(
 670        mut self,
 671        button: MouseButton,
 672        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 673    ) -> Self {
 674        self.interactivity().on_mouse_down(button, listener);
 675        self
 676    }
 677
 678    #[cfg(any(test, feature = "test-support"))]
 679    /// Set a key that can be used to look up this element's bounds
 680    /// in the [`VisualTestContext::debug_bounds`] map
 681    /// This is a noop in release builds
 682    fn debug_selector(mut self, f: impl FnOnce() -> String) -> Self {
 683        self.interactivity().debug_selector = Some(f());
 684        self
 685    }
 686
 687    #[cfg(not(any(test, feature = "test-support")))]
 688    /// Set a key that can be used to look up this element's bounds
 689    /// in the [`VisualTestContext::debug_bounds`] map
 690    /// This is a noop in release builds
 691    #[inline]
 692    fn debug_selector(self, _: impl FnOnce() -> String) -> Self {
 693        self
 694    }
 695
 696    /// Bind the given callback to the mouse down event for any button, during the capture phase
 697    /// the fluent API equivalent to [`Interactivity::capture_any_mouse_down`]
 698    ///
 699    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 700    fn capture_any_mouse_down(
 701        mut self,
 702        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 703    ) -> Self {
 704        self.interactivity().capture_any_mouse_down(listener);
 705        self
 706    }
 707
 708    /// Bind the given callback to the mouse down event for any button, during the capture phase
 709    /// the fluent API equivalent to [`Interactivity::on_any_mouse_down`]
 710    ///
 711    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 712    fn on_any_mouse_down(
 713        mut self,
 714        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 715    ) -> Self {
 716        self.interactivity().on_any_mouse_down(listener);
 717        self
 718    }
 719
 720    /// Bind the given callback to the mouse up event for the given button, during the bubble phase
 721    /// the fluent API equivalent to [`Interactivity::on_mouse_up`]
 722    ///
 723    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 724    fn on_mouse_up(
 725        mut self,
 726        button: MouseButton,
 727        listener: impl Fn(&MouseUpEvent, &mut Window, &mut App) + 'static,
 728    ) -> Self {
 729        self.interactivity().on_mouse_up(button, listener);
 730        self
 731    }
 732
 733    /// Bind the given callback to the mouse up event for any button, during the capture phase
 734    /// the fluent API equivalent to [`Interactivity::capture_any_mouse_up`]
 735    ///
 736    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 737    fn capture_any_mouse_up(
 738        mut self,
 739        listener: impl Fn(&MouseUpEvent, &mut Window, &mut App) + 'static,
 740    ) -> Self {
 741        self.interactivity().capture_any_mouse_up(listener);
 742        self
 743    }
 744
 745    /// Bind the given callback to the mouse down event, on any button, during the capture phase,
 746    /// when the mouse is outside of the bounds of this element.
 747    /// The fluent API equivalent to [`Interactivity::on_mouse_down_out`]
 748    ///
 749    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 750    fn on_mouse_down_out(
 751        mut self,
 752        listener: impl Fn(&MouseDownEvent, &mut Window, &mut App) + 'static,
 753    ) -> Self {
 754        self.interactivity().on_mouse_down_out(listener);
 755        self
 756    }
 757
 758    /// Bind the given callback to the mouse up event, for the given button, during the capture phase,
 759    /// when the mouse is outside of the bounds of this element.
 760    /// The fluent API equivalent to [`Interactivity::on_mouse_up_out`]
 761    ///
 762    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 763    fn on_mouse_up_out(
 764        mut self,
 765        button: MouseButton,
 766        listener: impl Fn(&MouseUpEvent, &mut Window, &mut App) + 'static,
 767    ) -> Self {
 768        self.interactivity().on_mouse_up_out(button, listener);
 769        self
 770    }
 771
 772    /// Bind the given callback to the mouse move event, during the bubble phase
 773    /// The fluent API equivalent to [`Interactivity::on_mouse_move`]
 774    ///
 775    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 776    fn on_mouse_move(
 777        mut self,
 778        listener: impl Fn(&MouseMoveEvent, &mut Window, &mut App) + 'static,
 779    ) -> Self {
 780        self.interactivity().on_mouse_move(listener);
 781        self
 782    }
 783
 784    /// Bind the given callback to the mouse drag event of the given type. Note that this
 785    /// will be called for all move events, inside or outside of this element, as long as the
 786    /// drag was started with this element under the mouse. Useful for implementing draggable
 787    /// UIs that don't conform to a drag and drop style interaction, like resizing.
 788    /// The fluent API equivalent to [`Interactivity::on_drag_move`]
 789    ///
 790    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 791    fn on_drag_move<T: 'static>(
 792        mut self,
 793        listener: impl Fn(&DragMoveEvent<T>, &mut Window, &mut App) + 'static,
 794    ) -> Self {
 795        self.interactivity().on_drag_move(listener);
 796        self
 797    }
 798
 799    /// Bind the given callback to scroll wheel events during the bubble phase
 800    /// The fluent API equivalent to [`Interactivity::on_scroll_wheel`]
 801    ///
 802    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 803    fn on_scroll_wheel(
 804        mut self,
 805        listener: impl Fn(&ScrollWheelEvent, &mut Window, &mut App) + 'static,
 806    ) -> Self {
 807        self.interactivity().on_scroll_wheel(listener);
 808        self
 809    }
 810
 811    /// Capture the given action, before normal action dispatch can fire
 812    /// The fluent API equivalent to [`Interactivity::on_scroll_wheel`]
 813    ///
 814    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 815    fn capture_action<A: Action>(
 816        mut self,
 817        listener: impl Fn(&A, &mut Window, &mut App) + 'static,
 818    ) -> Self {
 819        self.interactivity().capture_action(listener);
 820        self
 821    }
 822
 823    /// Bind the given callback to an action dispatch during the bubble phase
 824    /// The fluent API equivalent to [`Interactivity::on_action`]
 825    ///
 826    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 827    fn on_action<A: Action>(
 828        mut self,
 829        listener: impl Fn(&A, &mut Window, &mut App) + 'static,
 830    ) -> Self {
 831        self.interactivity().on_action(listener);
 832        self
 833    }
 834
 835    /// Bind the given callback to an action dispatch, based on a dynamic action parameter
 836    /// instead of a type parameter. Useful for component libraries that want to expose
 837    /// action bindings to their users.
 838    /// The fluent API equivalent to [`Interactivity::on_boxed_action`]
 839    ///
 840    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 841    fn on_boxed_action(
 842        mut self,
 843        action: &dyn Action,
 844        listener: impl Fn(&dyn Action, &mut Window, &mut App) + 'static,
 845    ) -> Self {
 846        self.interactivity().on_boxed_action(action, listener);
 847        self
 848    }
 849
 850    /// Bind the given callback to key down events during the bubble phase
 851    /// The fluent API equivalent to [`Interactivity::on_key_down`]
 852    ///
 853    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 854    fn on_key_down(
 855        mut self,
 856        listener: impl Fn(&KeyDownEvent, &mut Window, &mut App) + 'static,
 857    ) -> Self {
 858        self.interactivity().on_key_down(listener);
 859        self
 860    }
 861
 862    /// Bind the given callback to key down events during the capture phase
 863    /// The fluent API equivalent to [`Interactivity::capture_key_down`]
 864    ///
 865    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 866    fn capture_key_down(
 867        mut self,
 868        listener: impl Fn(&KeyDownEvent, &mut Window, &mut App) + 'static,
 869    ) -> Self {
 870        self.interactivity().capture_key_down(listener);
 871        self
 872    }
 873
 874    /// Bind the given callback to key up events during the bubble phase
 875    /// The fluent API equivalent to [`Interactivity::on_key_up`]
 876    ///
 877    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 878    fn on_key_up(
 879        mut self,
 880        listener: impl Fn(&KeyUpEvent, &mut Window, &mut App) + 'static,
 881    ) -> Self {
 882        self.interactivity().on_key_up(listener);
 883        self
 884    }
 885
 886    /// Bind the given callback to key up events during the capture phase
 887    /// The fluent API equivalent to [`Interactivity::capture_key_up`]
 888    ///
 889    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 890    fn capture_key_up(
 891        mut self,
 892        listener: impl Fn(&KeyUpEvent, &mut Window, &mut App) + 'static,
 893    ) -> Self {
 894        self.interactivity().capture_key_up(listener);
 895        self
 896    }
 897
 898    /// Bind the given callback to modifiers changing events.
 899    /// The fluent API equivalent to [`Interactivity::on_modifiers_changed`]
 900    ///
 901    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 902    fn on_modifiers_changed(
 903        mut self,
 904        listener: impl Fn(&ModifiersChangedEvent, &mut Window, &mut App) + 'static,
 905    ) -> Self {
 906        self.interactivity().on_modifiers_changed(listener);
 907        self
 908    }
 909
 910    /// Apply the given style when the given data type is dragged over this element
 911    fn drag_over<S: 'static>(
 912        mut self,
 913        f: impl 'static + Fn(StyleRefinement, &S, &mut Window, &mut App) -> StyleRefinement,
 914    ) -> Self {
 915        self.interactivity().drag_over_styles.push((
 916            TypeId::of::<S>(),
 917            Box::new(move |currently_dragged: &dyn Any, window, cx| {
 918                f(
 919                    StyleRefinement::default(),
 920                    currently_dragged.downcast_ref::<S>().unwrap(),
 921                    window,
 922                    cx,
 923                )
 924            }),
 925        ));
 926        self
 927    }
 928
 929    /// Apply the given style when the given data type is dragged over this element's group
 930    fn group_drag_over<S: 'static>(
 931        mut self,
 932        group_name: impl Into<SharedString>,
 933        f: impl FnOnce(StyleRefinement) -> StyleRefinement,
 934    ) -> Self {
 935        self.interactivity().group_drag_over_styles.push((
 936            TypeId::of::<S>(),
 937            GroupStyle {
 938                group: group_name.into(),
 939                style: Box::new(f(StyleRefinement::default())),
 940            },
 941        ));
 942        self
 943    }
 944
 945    /// Bind the given callback to drop events of the given type, whether or not the drag started on this element
 946    /// The fluent API equivalent to [`Interactivity::on_drop`]
 947    ///
 948    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
 949    fn on_drop<T: 'static>(
 950        mut self,
 951        listener: impl Fn(&T, &mut Window, &mut App) + 'static,
 952    ) -> Self {
 953        self.interactivity().on_drop(listener);
 954        self
 955    }
 956
 957    /// Use the given predicate to determine whether or not a drop event should be dispatched to this element
 958    /// The fluent API equivalent to [`Interactivity::can_drop`]
 959    fn can_drop(
 960        mut self,
 961        predicate: impl Fn(&dyn Any, &mut Window, &mut App) -> bool + 'static,
 962    ) -> Self {
 963        self.interactivity().can_drop(predicate);
 964        self
 965    }
 966
 967    /// Block the mouse from all interactions with elements behind this element's hitbox. Typically
 968    /// `block_mouse_except_scroll` should be preferred.
 969    /// The fluent API equivalent to [`Interactivity::occlude_mouse`]
 970    fn occlude(mut self) -> Self {
 971        self.interactivity().occlude_mouse();
 972        self
 973    }
 974
 975    /// Set the bounds of this element as a window control area for the platform window.
 976    /// The fluent API equivalent to [`Interactivity::window_control_area`]
 977    fn window_control_area(mut self, area: WindowControlArea) -> Self {
 978        self.interactivity().window_control_area(area);
 979        self
 980    }
 981
 982    /// Block non-scroll mouse interactions with elements behind this element's hitbox. See
 983    /// [`Hitbox::is_hovered`] for details.
 984    ///
 985    /// The fluent API equivalent to [`Interactivity::block_mouse_except_scroll`]
 986    fn block_mouse_except_scroll(mut self) -> Self {
 987        self.interactivity().block_mouse_except_scroll();
 988        self
 989    }
 990
 991    /// Set the given styles to be applied when this element, specifically, is focused.
 992    /// Requires that the element is focusable. Elements can be made focusable using [`InteractiveElement::track_focus`].
 993    fn focus(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
 994    where
 995        Self: Sized,
 996    {
 997        self.interactivity().focus_style = Some(Box::new(f(StyleRefinement::default())));
 998        self
 999    }
1000
1001    /// Set the given styles to be applied when this element is inside another element that is focused.
1002    /// Requires that the element is focusable. Elements can be made focusable using [`InteractiveElement::track_focus`].
1003    fn in_focus(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
1004    where
1005        Self: Sized,
1006    {
1007        self.interactivity().in_focus_style = Some(Box::new(f(StyleRefinement::default())));
1008        self
1009    }
1010}
1011
1012/// A trait for elements that want to use the standard GPUI interactivity features
1013/// that require state.
1014pub trait StatefulInteractiveElement: InteractiveElement {
1015    /// Set this element to focusable.
1016    fn focusable(mut self) -> Self {
1017        self.interactivity().focusable = true;
1018        self
1019    }
1020
1021    /// Set the overflow x and y to scroll.
1022    fn overflow_scroll(mut self) -> Self {
1023        self.interactivity().base_style.overflow.x = Some(Overflow::Scroll);
1024        self.interactivity().base_style.overflow.y = Some(Overflow::Scroll);
1025        self
1026    }
1027
1028    /// Set the overflow x to scroll.
1029    fn overflow_x_scroll(mut self) -> Self {
1030        self.interactivity().base_style.overflow.x = Some(Overflow::Scroll);
1031        self
1032    }
1033
1034    /// Set the overflow y to scroll.
1035    fn overflow_y_scroll(mut self) -> Self {
1036        self.interactivity().base_style.overflow.y = Some(Overflow::Scroll);
1037        self
1038    }
1039
1040    /// Track the scroll state of this element with the given handle.
1041    fn track_scroll(mut self, scroll_handle: &ScrollHandle) -> Self {
1042        self.interactivity().tracked_scroll_handle = Some(scroll_handle.clone());
1043        self
1044    }
1045
1046    /// Track the scroll state of this element with the given handle.
1047    fn anchor_scroll(mut self, scroll_anchor: Option<ScrollAnchor>) -> Self {
1048        self.interactivity().scroll_anchor = scroll_anchor;
1049        self
1050    }
1051
1052    /// Set the given styles to be applied when this element is active.
1053    fn active(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
1054    where
1055        Self: Sized,
1056    {
1057        self.interactivity().active_style = Some(Box::new(f(StyleRefinement::default())));
1058        self
1059    }
1060
1061    /// Set the given styles to be applied when this element's group is active.
1062    fn group_active(
1063        mut self,
1064        group_name: impl Into<SharedString>,
1065        f: impl FnOnce(StyleRefinement) -> StyleRefinement,
1066    ) -> Self
1067    where
1068        Self: Sized,
1069    {
1070        self.interactivity().group_active_style = Some(GroupStyle {
1071            group: group_name.into(),
1072            style: Box::new(f(StyleRefinement::default())),
1073        });
1074        self
1075    }
1076
1077    /// Bind the given callback to click events of this element
1078    /// The fluent API equivalent to [`Interactivity::on_click`]
1079    ///
1080    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
1081    fn on_click(mut self, listener: impl Fn(&ClickEvent, &mut Window, &mut App) + 'static) -> Self
1082    where
1083        Self: Sized,
1084    {
1085        self.interactivity().on_click(listener);
1086        self
1087    }
1088
1089    /// On drag initiation, this callback will be used to create a new view to render the dragged value for a
1090    /// drag and drop operation. This API should also be used as the equivalent of 'on drag start' with
1091    /// the [`Self::on_drag_move`] API.
1092    /// The callback also has access to the offset of triggering click from the origin of parent element.
1093    /// The fluent API equivalent to [`Interactivity::on_drag`]
1094    ///
1095    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
1096    fn on_drag<T, W>(
1097        mut self,
1098        value: T,
1099        constructor: impl Fn(&T, Point<Pixels>, &mut Window, &mut App) -> Entity<W> + 'static,
1100    ) -> Self
1101    where
1102        Self: Sized,
1103        T: 'static,
1104        W: 'static + Render,
1105    {
1106        self.interactivity().on_drag(value, constructor);
1107        self
1108    }
1109
1110    /// Bind the given callback on the hover start and end events of this element. Note that the boolean
1111    /// passed to the callback is true when the hover starts and false when it ends.
1112    /// The fluent API equivalent to [`Interactivity::on_hover`]
1113    ///
1114    /// See [`Context::listener`](crate::Context::listener) to get access to a view's state from this callback.
1115    fn on_hover(mut self, listener: impl Fn(&bool, &mut Window, &mut App) + 'static) -> Self
1116    where
1117        Self: Sized,
1118    {
1119        self.interactivity().on_hover(listener);
1120        self
1121    }
1122
1123    /// Use the given callback to construct a new tooltip view when the mouse hovers over this element.
1124    /// The fluent API equivalent to [`Interactivity::tooltip`]
1125    fn tooltip(mut self, build_tooltip: impl Fn(&mut Window, &mut App) -> AnyView + 'static) -> Self
1126    where
1127        Self: Sized,
1128    {
1129        self.interactivity().tooltip(build_tooltip);
1130        self
1131    }
1132
1133    /// Use the given callback to construct a new tooltip view when the mouse hovers over this element.
1134    /// The tooltip itself is also hoverable and won't disappear when the user moves the mouse into
1135    /// the tooltip. The fluent API equivalent to [`Interactivity::hoverable_tooltip`]
1136    fn hoverable_tooltip(
1137        mut self,
1138        build_tooltip: impl Fn(&mut Window, &mut App) -> AnyView + 'static,
1139    ) -> Self
1140    where
1141        Self: Sized,
1142    {
1143        self.interactivity().hoverable_tooltip(build_tooltip);
1144        self
1145    }
1146}
1147
1148pub(crate) type MouseDownListener =
1149    Box<dyn Fn(&MouseDownEvent, DispatchPhase, &Hitbox, &mut Window, &mut App) + 'static>;
1150pub(crate) type MouseUpListener =
1151    Box<dyn Fn(&MouseUpEvent, DispatchPhase, &Hitbox, &mut Window, &mut App) + 'static>;
1152
1153pub(crate) type MouseMoveListener =
1154    Box<dyn Fn(&MouseMoveEvent, DispatchPhase, &Hitbox, &mut Window, &mut App) + 'static>;
1155
1156pub(crate) type ScrollWheelListener =
1157    Box<dyn Fn(&ScrollWheelEvent, DispatchPhase, &Hitbox, &mut Window, &mut App) + 'static>;
1158
1159pub(crate) type ClickListener = Rc<dyn Fn(&ClickEvent, &mut Window, &mut App) + 'static>;
1160
1161pub(crate) type DragListener =
1162    Box<dyn Fn(&dyn Any, Point<Pixels>, &mut Window, &mut App) -> AnyView + 'static>;
1163
1164type DropListener = Box<dyn Fn(&dyn Any, &mut Window, &mut App) + 'static>;
1165
1166type CanDropPredicate = Box<dyn Fn(&dyn Any, &mut Window, &mut App) -> bool + 'static>;
1167
1168pub(crate) struct TooltipBuilder {
1169    build: Rc<dyn Fn(&mut Window, &mut App) -> AnyView + 'static>,
1170    hoverable: bool,
1171}
1172
1173pub(crate) type KeyDownListener =
1174    Box<dyn Fn(&KeyDownEvent, DispatchPhase, &mut Window, &mut App) + 'static>;
1175
1176pub(crate) type KeyUpListener =
1177    Box<dyn Fn(&KeyUpEvent, DispatchPhase, &mut Window, &mut App) + 'static>;
1178
1179pub(crate) type ModifiersChangedListener =
1180    Box<dyn Fn(&ModifiersChangedEvent, &mut Window, &mut App) + 'static>;
1181
1182pub(crate) type ActionListener =
1183    Box<dyn Fn(&dyn Any, DispatchPhase, &mut Window, &mut App) + 'static>;
1184
1185/// Construct a new [`Div`] element
1186#[track_caller]
1187pub fn div() -> Div {
1188    Div {
1189        interactivity: Interactivity::new(),
1190        children: SmallVec::default(),
1191        prepaint_listener: None,
1192        image_cache: None,
1193    }
1194}
1195
1196/// A [`Div`] element, the all-in-one element for building complex UIs in GPUI
1197pub struct Div {
1198    interactivity: Interactivity,
1199    children: SmallVec<[AnyElement; 2]>,
1200    prepaint_listener: Option<Box<dyn Fn(Vec<Bounds<Pixels>>, &mut Window, &mut App) + 'static>>,
1201    image_cache: Option<Box<dyn ImageCacheProvider>>,
1202}
1203
1204impl Div {
1205    /// Add a listener to be called when the children of this `Div` are prepainted.
1206    /// This allows you to store the [`Bounds`] of the children for later use.
1207    pub fn on_children_prepainted(
1208        mut self,
1209        listener: impl Fn(Vec<Bounds<Pixels>>, &mut Window, &mut App) + 'static,
1210    ) -> Self {
1211        self.prepaint_listener = Some(Box::new(listener));
1212        self
1213    }
1214
1215    /// Add an image cache at the location of this div in the element tree.
1216    pub fn image_cache(mut self, cache: impl ImageCacheProvider) -> Self {
1217        self.image_cache = Some(Box::new(cache));
1218        self
1219    }
1220}
1221
1222/// A frame state for a `Div` element, which contains layout IDs for its children.
1223///
1224/// This struct is used internally by the `Div` element to manage the layout state of its children
1225/// during the UI update cycle. It holds a small vector of `LayoutId` values, each corresponding to
1226/// a child element of the `Div`. These IDs are used to query the layout engine for the computed
1227/// bounds of the children after the layout phase is complete.
1228pub struct DivFrameState {
1229    child_layout_ids: SmallVec<[LayoutId; 2]>,
1230}
1231
1232/// Interactivity state displayed an manipulated in the inspector.
1233#[derive(Clone)]
1234pub struct DivInspectorState {
1235    /// The inspected element's base style. This is used for both inspecting and modifying the
1236    /// state. In the future it will make sense to separate the read and write, possibly tracking
1237    /// the modifications.
1238    #[cfg(any(feature = "inspector", debug_assertions))]
1239    pub base_style: Box<StyleRefinement>,
1240    /// Inspects the bounds of the element.
1241    pub bounds: Bounds<Pixels>,
1242    /// Size of the children of the element, or `bounds.size` if it has no children.
1243    pub content_size: Size<Pixels>,
1244}
1245
1246impl Styled for Div {
1247    fn style(&mut self) -> &mut StyleRefinement {
1248        &mut self.interactivity.base_style
1249    }
1250}
1251
1252impl InteractiveElement for Div {
1253    fn interactivity(&mut self) -> &mut Interactivity {
1254        &mut self.interactivity
1255    }
1256}
1257
1258impl ParentElement for Div {
1259    fn extend(&mut self, elements: impl IntoIterator<Item = AnyElement>) {
1260        self.children.extend(elements)
1261    }
1262}
1263
1264impl Element for Div {
1265    type RequestLayoutState = DivFrameState;
1266    type PrepaintState = Option<Hitbox>;
1267
1268    fn id(&self) -> Option<ElementId> {
1269        self.interactivity.element_id.clone()
1270    }
1271
1272    fn source_location(&self) -> Option<&'static std::panic::Location<'static>> {
1273        self.interactivity.source_location()
1274    }
1275
1276    fn request_layout(
1277        &mut self,
1278        global_id: Option<&GlobalElementId>,
1279        inspector_id: Option<&InspectorElementId>,
1280        window: &mut Window,
1281        cx: &mut App,
1282    ) -> (LayoutId, Self::RequestLayoutState) {
1283        let mut child_layout_ids = SmallVec::new();
1284        let image_cache = self
1285            .image_cache
1286            .as_mut()
1287            .map(|provider| provider.provide(window, cx));
1288
1289        let layout_id = window.with_image_cache(image_cache, |window| {
1290            self.interactivity.request_layout(
1291                global_id,
1292                inspector_id,
1293                window,
1294                cx,
1295                |style, window, cx| {
1296                    window.with_text_style(style.text_style().cloned(), |window| {
1297                        child_layout_ids = self
1298                            .children
1299                            .iter_mut()
1300                            .map(|child| child.request_layout(window, cx))
1301                            .collect::<SmallVec<_>>();
1302                        let layout_id =
1303                            window.request_layout(style, child_layout_ids.iter().copied(), cx);
1304                        if let Some(global_id) = global_id.as_ref()
1305                            && global_id.0.ends_with(&["api-key-editor".into()])
1306                        {
1307                            LAYOUT_ID_TO_DEBUG.with_borrow_mut(|layout_id_to_debug| {
1308                                *layout_id_to_debug = Some(layout_id)
1309                            });
1310                        }
1311                        if let Some(global_id) = global_id.as_ref()
1312                            && global_id.0.ends_with(&["open-router-container".into()])
1313                        {
1314                            CONTAINER_LAYOUT_ID_TO_DEBUG.with_borrow_mut(|layout_id_to_debug| {
1315                                *layout_id_to_debug = Some(layout_id)
1316                            });
1317                        }
1318                        layout_id
1319                    })
1320                },
1321            )
1322        });
1323
1324        (layout_id, DivFrameState { child_layout_ids })
1325    }
1326
1327    fn prepaint(
1328        &mut self,
1329        global_id: Option<&GlobalElementId>,
1330        inspector_id: Option<&InspectorElementId>,
1331        bounds: Bounds<Pixels>,
1332        request_layout: &mut Self::RequestLayoutState,
1333        window: &mut Window,
1334        cx: &mut App,
1335    ) -> Option<Hitbox> {
1336        let has_prepaint_listener = self.prepaint_listener.is_some();
1337        let mut children_bounds = Vec::with_capacity(if has_prepaint_listener {
1338            request_layout.child_layout_ids.len()
1339        } else {
1340            0
1341        });
1342
1343        let mut child_min = point(Pixels::MAX, Pixels::MAX);
1344        let mut child_max = Point::default();
1345        if let Some(handle) = self.interactivity.scroll_anchor.as_ref() {
1346            *handle.last_origin.borrow_mut() = bounds.origin - window.element_offset();
1347        }
1348        let content_size = if request_layout.child_layout_ids.is_empty() {
1349            bounds.size
1350        } else if let Some(scroll_handle) = self.interactivity.tracked_scroll_handle.as_ref() {
1351            let mut state = scroll_handle.0.borrow_mut();
1352            state.child_bounds = Vec::with_capacity(request_layout.child_layout_ids.len());
1353            for child_layout_id in &request_layout.child_layout_ids {
1354                let child_bounds = window.layout_bounds(*child_layout_id);
1355                child_min = child_min.min(&child_bounds.origin);
1356                child_max = child_max.max(&child_bounds.bottom_right());
1357                state.child_bounds.push(child_bounds);
1358            }
1359            (child_max - child_min).into()
1360        } else {
1361            for child_layout_id in &request_layout.child_layout_ids {
1362                let child_bounds = window.layout_bounds(*child_layout_id);
1363                child_min = child_min.min(&child_bounds.origin);
1364                child_max = child_max.max(&child_bounds.bottom_right());
1365
1366                if has_prepaint_listener {
1367                    children_bounds.push(child_bounds);
1368                }
1369            }
1370            (child_max - child_min).into()
1371        };
1372
1373        self.interactivity.prepaint(
1374            global_id,
1375            inspector_id,
1376            bounds,
1377            content_size,
1378            window,
1379            cx,
1380            |_style, scroll_offset, hitbox, window, cx| {
1381                window.with_element_offset(scroll_offset, |window| {
1382                    for child in &mut self.children {
1383                        child.prepaint(window, cx);
1384                    }
1385                });
1386
1387                if let Some(listener) = self.prepaint_listener.as_ref() {
1388                    listener(children_bounds, window, cx);
1389                }
1390
1391                hitbox
1392            },
1393        )
1394    }
1395
1396    fn paint(
1397        &mut self,
1398        global_id: Option<&GlobalElementId>,
1399        inspector_id: Option<&InspectorElementId>,
1400        bounds: Bounds<Pixels>,
1401        _request_layout: &mut Self::RequestLayoutState,
1402        hitbox: &mut Option<Hitbox>,
1403        window: &mut Window,
1404        cx: &mut App,
1405    ) {
1406        let image_cache = self
1407            .image_cache
1408            .as_mut()
1409            .map(|provider| provider.provide(window, cx));
1410
1411        window.with_image_cache(image_cache, |window| {
1412            self.interactivity.paint(
1413                global_id,
1414                inspector_id,
1415                bounds,
1416                hitbox.as_ref(),
1417                window,
1418                cx,
1419                |_style, window, cx| {
1420                    for child in &mut self.children {
1421                        child.paint(window, cx);
1422                    }
1423                },
1424            )
1425        });
1426    }
1427}
1428
1429impl IntoElement for Div {
1430    type Element = Self;
1431
1432    fn into_element(self) -> Self::Element {
1433        self
1434    }
1435}
1436
1437/// The interactivity struct. Powers all of the general-purpose
1438/// interactivity in the `Div` element.
1439#[derive(Default)]
1440pub struct Interactivity {
1441    /// The element ID of the element. In id is required to support a stateful subset of the interactivity such as on_click.
1442    pub element_id: Option<ElementId>,
1443    /// Whether the element was clicked. This will only be present after layout.
1444    pub active: Option<bool>,
1445    /// Whether the element was hovered. This will only be present after paint if an hitbox
1446    /// was created for the interactive element.
1447    pub hovered: Option<bool>,
1448    pub(crate) tooltip_id: Option<TooltipId>,
1449    pub(crate) content_size: Size<Pixels>,
1450    pub(crate) key_context: Option<KeyContext>,
1451    pub(crate) focusable: bool,
1452    pub(crate) tracked_focus_handle: Option<FocusHandle>,
1453    pub(crate) tracked_scroll_handle: Option<ScrollHandle>,
1454    pub(crate) scroll_anchor: Option<ScrollAnchor>,
1455    pub(crate) scroll_offset: Option<Rc<RefCell<Point<Pixels>>>>,
1456    pub(crate) group: Option<SharedString>,
1457    /// The base style of the element, before any modifications are applied
1458    /// by focus, active, etc.
1459    pub base_style: Box<StyleRefinement>,
1460    pub(crate) focus_style: Option<Box<StyleRefinement>>,
1461    pub(crate) in_focus_style: Option<Box<StyleRefinement>>,
1462    pub(crate) hover_style: Option<Box<StyleRefinement>>,
1463    pub(crate) group_hover_style: Option<GroupStyle>,
1464    pub(crate) active_style: Option<Box<StyleRefinement>>,
1465    pub(crate) group_active_style: Option<GroupStyle>,
1466    pub(crate) drag_over_styles: Vec<(
1467        TypeId,
1468        Box<dyn Fn(&dyn Any, &mut Window, &mut App) -> StyleRefinement>,
1469    )>,
1470    pub(crate) group_drag_over_styles: Vec<(TypeId, GroupStyle)>,
1471    pub(crate) mouse_down_listeners: Vec<MouseDownListener>,
1472    pub(crate) mouse_up_listeners: Vec<MouseUpListener>,
1473    pub(crate) mouse_move_listeners: Vec<MouseMoveListener>,
1474    pub(crate) scroll_wheel_listeners: Vec<ScrollWheelListener>,
1475    pub(crate) key_down_listeners: Vec<KeyDownListener>,
1476    pub(crate) key_up_listeners: Vec<KeyUpListener>,
1477    pub(crate) modifiers_changed_listeners: Vec<ModifiersChangedListener>,
1478    pub(crate) action_listeners: Vec<(TypeId, ActionListener)>,
1479    pub(crate) drop_listeners: Vec<(TypeId, DropListener)>,
1480    pub(crate) can_drop_predicate: Option<CanDropPredicate>,
1481    pub(crate) click_listeners: Vec<ClickListener>,
1482    pub(crate) drag_listener: Option<(Arc<dyn Any>, DragListener)>,
1483    pub(crate) hover_listener: Option<Box<dyn Fn(&bool, &mut Window, &mut App)>>,
1484    pub(crate) tooltip_builder: Option<TooltipBuilder>,
1485    pub(crate) window_control: Option<WindowControlArea>,
1486    pub(crate) hitbox_behavior: HitboxBehavior,
1487    pub(crate) tab_index: Option<isize>,
1488
1489    #[cfg(any(feature = "inspector", debug_assertions))]
1490    pub(crate) source_location: Option<&'static core::panic::Location<'static>>,
1491
1492    #[cfg(any(test, feature = "test-support"))]
1493    pub(crate) debug_selector: Option<String>,
1494}
1495
1496impl Interactivity {
1497    /// Layout this element according to this interactivity state's configured styles
1498    pub fn request_layout(
1499        &mut self,
1500        global_id: Option<&GlobalElementId>,
1501        _inspector_id: Option<&InspectorElementId>,
1502        window: &mut Window,
1503        cx: &mut App,
1504        f: impl FnOnce(Style, &mut Window, &mut App) -> LayoutId,
1505    ) -> LayoutId {
1506        #[cfg(any(feature = "inspector", debug_assertions))]
1507        window.with_inspector_state(
1508            _inspector_id,
1509            cx,
1510            |inspector_state: &mut Option<DivInspectorState>, _window| {
1511                if let Some(inspector_state) = inspector_state {
1512                    self.base_style = inspector_state.base_style.clone();
1513                } else {
1514                    *inspector_state = Some(DivInspectorState {
1515                        base_style: self.base_style.clone(),
1516                        bounds: Default::default(),
1517                        content_size: Default::default(),
1518                    })
1519                }
1520            },
1521        );
1522
1523        window.with_optional_element_state::<InteractiveElementState, _>(
1524            global_id,
1525            |element_state, window| {
1526                let mut element_state =
1527                    element_state.map(|element_state| element_state.unwrap_or_default());
1528
1529                if let Some(element_state) = element_state.as_ref() {
1530                    if cx.has_active_drag() {
1531                        if let Some(pending_mouse_down) = element_state.pending_mouse_down.as_ref()
1532                        {
1533                            *pending_mouse_down.borrow_mut() = None;
1534                        }
1535                        if let Some(clicked_state) = element_state.clicked_state.as_ref() {
1536                            *clicked_state.borrow_mut() = ElementClickedState::default();
1537                        }
1538                    }
1539                }
1540
1541                // Ensure we store a focus handle in our element state if we're focusable.
1542                // If there's an explicit focus handle we're tracking, use that. Otherwise
1543                // create a new handle and store it in the element state, which lives for as
1544                // as frames contain an element with this id.
1545                if self.focusable && self.tracked_focus_handle.is_none() {
1546                    if let Some(element_state) = element_state.as_mut() {
1547                        let mut handle = element_state
1548                            .focus_handle
1549                            .get_or_insert_with(|| cx.focus_handle())
1550                            .clone()
1551                            .tab_stop(false);
1552
1553                        if let Some(index) = self.tab_index {
1554                            handle = handle.tab_index(index).tab_stop(true);
1555                        }
1556
1557                        self.tracked_focus_handle = Some(handle);
1558                    }
1559                }
1560
1561                if let Some(scroll_handle) = self.tracked_scroll_handle.as_ref() {
1562                    self.scroll_offset = Some(scroll_handle.0.borrow().offset.clone());
1563                } else if self.base_style.overflow.x == Some(Overflow::Scroll)
1564                    || self.base_style.overflow.y == Some(Overflow::Scroll)
1565                {
1566                    if let Some(element_state) = element_state.as_mut() {
1567                        self.scroll_offset = Some(
1568                            element_state
1569                                .scroll_offset
1570                                .get_or_insert_with(Rc::default)
1571                                .clone(),
1572                        );
1573                    }
1574                }
1575
1576                let style = self.compute_style_internal(None, element_state.as_mut(), window, cx);
1577                let layout_id = f(style, window, cx);
1578                (layout_id, element_state)
1579            },
1580        )
1581    }
1582
1583    /// Commit the bounds of this element according to this interactivity state's configured styles.
1584    pub fn prepaint<R>(
1585        &mut self,
1586        global_id: Option<&GlobalElementId>,
1587        _inspector_id: Option<&InspectorElementId>,
1588        bounds: Bounds<Pixels>,
1589        content_size: Size<Pixels>,
1590        window: &mut Window,
1591        cx: &mut App,
1592        f: impl FnOnce(&Style, Point<Pixels>, Option<Hitbox>, &mut Window, &mut App) -> R,
1593    ) -> R {
1594        self.content_size = content_size;
1595
1596        #[cfg(any(feature = "inspector", debug_assertions))]
1597        window.with_inspector_state(
1598            _inspector_id,
1599            cx,
1600            |inspector_state: &mut Option<DivInspectorState>, _window| {
1601                if let Some(inspector_state) = inspector_state {
1602                    inspector_state.bounds = bounds;
1603                    inspector_state.content_size = content_size;
1604                }
1605            },
1606        );
1607
1608        if let Some(focus_handle) = self.tracked_focus_handle.as_ref() {
1609            window.set_focus_handle(focus_handle, cx);
1610        }
1611        window.with_optional_element_state::<InteractiveElementState, _>(
1612            global_id,
1613            |element_state, window| {
1614                let mut element_state =
1615                    element_state.map(|element_state| element_state.unwrap_or_default());
1616                let style = self.compute_style_internal(None, element_state.as_mut(), window, cx);
1617
1618                if let Some(element_state) = element_state.as_mut() {
1619                    if let Some(clicked_state) = element_state.clicked_state.as_ref() {
1620                        let clicked_state = clicked_state.borrow();
1621                        self.active = Some(clicked_state.element);
1622                    }
1623                    if let Some(active_tooltip) = element_state.active_tooltip.as_ref() {
1624                        if self.tooltip_builder.is_some() {
1625                            self.tooltip_id = set_tooltip_on_window(active_tooltip, window);
1626                        } else {
1627                            // If there is no longer a tooltip builder, remove the active tooltip.
1628                            element_state.active_tooltip.take();
1629                        }
1630                    }
1631                }
1632
1633                window.with_text_style(style.text_style().cloned(), |window| {
1634                    window.with_content_mask(
1635                        style.overflow_mask(bounds, window.rem_size()),
1636                        |window| {
1637                            let hitbox = if self.should_insert_hitbox(&style, window, cx) {
1638                                Some(window.insert_hitbox(bounds, self.hitbox_behavior))
1639                            } else {
1640                                None
1641                            };
1642
1643                            let scroll_offset =
1644                                self.clamp_scroll_position(bounds, &style, window, cx);
1645                            let result = f(&style, scroll_offset, hitbox, window, cx);
1646                            (result, element_state)
1647                        },
1648                    )
1649                })
1650            },
1651        )
1652    }
1653
1654    fn should_insert_hitbox(&self, style: &Style, window: &Window, cx: &App) -> bool {
1655        self.hitbox_behavior != HitboxBehavior::Normal
1656            || self.window_control.is_some()
1657            || style.mouse_cursor.is_some()
1658            || self.group.is_some()
1659            || self.scroll_offset.is_some()
1660            || self.tracked_focus_handle.is_some()
1661            || self.hover_style.is_some()
1662            || self.group_hover_style.is_some()
1663            || self.hover_listener.is_some()
1664            || !self.mouse_up_listeners.is_empty()
1665            || !self.mouse_down_listeners.is_empty()
1666            || !self.mouse_move_listeners.is_empty()
1667            || !self.click_listeners.is_empty()
1668            || !self.scroll_wheel_listeners.is_empty()
1669            || self.drag_listener.is_some()
1670            || !self.drop_listeners.is_empty()
1671            || self.tooltip_builder.is_some()
1672            || window.is_inspector_picking(cx)
1673    }
1674
1675    fn clamp_scroll_position(
1676        &self,
1677        bounds: Bounds<Pixels>,
1678        style: &Style,
1679        window: &mut Window,
1680        _cx: &mut App,
1681    ) -> Point<Pixels> {
1682        fn round_to_two_decimals(pixels: Pixels) -> Pixels {
1683            const ROUNDING_FACTOR: f32 = 100.0;
1684            (pixels * ROUNDING_FACTOR).round() / ROUNDING_FACTOR
1685        }
1686
1687        if let Some(scroll_offset) = self.scroll_offset.as_ref() {
1688            let mut scroll_to_bottom = false;
1689            let mut tracked_scroll_handle = self
1690                .tracked_scroll_handle
1691                .as_ref()
1692                .map(|handle| handle.0.borrow_mut());
1693            if let Some(mut scroll_handle_state) = tracked_scroll_handle.as_deref_mut() {
1694                scroll_handle_state.overflow = style.overflow;
1695                scroll_to_bottom = mem::take(&mut scroll_handle_state.scroll_to_bottom);
1696            }
1697
1698            let rem_size = window.rem_size();
1699            let padding = style.padding.to_pixels(bounds.size.into(), rem_size);
1700            let padding_size = size(padding.left + padding.right, padding.top + padding.bottom);
1701            // The floating point values produced by Taffy and ours often vary
1702            // slightly after ~5 decimal places. This can lead to cases where after
1703            // subtracting these, the container becomes scrollable for less than
1704            // 0.00000x pixels. As we generally don't benefit from a precision that
1705            // high for the maximum scroll, we round the scroll max to 2 decimal
1706            // places here.
1707            let padded_content_size = self.content_size + padding_size;
1708            let scroll_max = (padded_content_size - bounds.size)
1709                .map(round_to_two_decimals)
1710                .max(&Default::default());
1711            // Clamp scroll offset in case scroll max is smaller now (e.g., if children
1712            // were removed or the bounds became larger).
1713            let mut scroll_offset = scroll_offset.borrow_mut();
1714
1715            scroll_offset.x = scroll_offset.x.clamp(-scroll_max.width, px(0.));
1716            if scroll_to_bottom {
1717                scroll_offset.y = -scroll_max.height;
1718            } else {
1719                scroll_offset.y = scroll_offset.y.clamp(-scroll_max.height, px(0.));
1720            }
1721
1722            if let Some(mut scroll_handle_state) = tracked_scroll_handle {
1723                scroll_handle_state.max_offset = scroll_max;
1724                scroll_handle_state.bounds = bounds;
1725            }
1726
1727            *scroll_offset
1728        } else {
1729            Point::default()
1730        }
1731    }
1732
1733    /// Paint this element according to this interactivity state's configured styles
1734    /// and bind the element's mouse and keyboard events.
1735    ///
1736    /// content_size is the size of the content of the element, which may be larger than the
1737    /// element's bounds if the element is scrollable.
1738    ///
1739    /// the final computed style will be passed to the provided function, along
1740    /// with the current scroll offset
1741    pub fn paint(
1742        &mut self,
1743        global_id: Option<&GlobalElementId>,
1744        _inspector_id: Option<&InspectorElementId>,
1745        bounds: Bounds<Pixels>,
1746        hitbox: Option<&Hitbox>,
1747        window: &mut Window,
1748        cx: &mut App,
1749        f: impl FnOnce(&Style, &mut Window, &mut App),
1750    ) {
1751        self.hovered = hitbox.map(|hitbox| hitbox.is_hovered(window));
1752        window.with_optional_element_state::<InteractiveElementState, _>(
1753            global_id,
1754            |element_state, window| {
1755                let mut element_state =
1756                    element_state.map(|element_state| element_state.unwrap_or_default());
1757
1758                let style = self.compute_style_internal(hitbox, element_state.as_mut(), window, cx);
1759
1760                #[cfg(any(feature = "test-support", test))]
1761                if let Some(debug_selector) = &self.debug_selector {
1762                    window
1763                        .next_frame
1764                        .debug_bounds
1765                        .insert(debug_selector.clone(), bounds);
1766                }
1767
1768                self.paint_hover_group_handler(window, cx);
1769
1770                if style.visibility == Visibility::Hidden {
1771                    return ((), element_state);
1772                }
1773
1774                if let Some(focus_handle) = &self.tracked_focus_handle {
1775                    window.next_frame.tab_handles.insert(focus_handle);
1776                }
1777
1778                window.with_element_opacity(style.opacity, |window| {
1779                    style.paint(bounds, window, cx, |window: &mut Window, cx: &mut App| {
1780                        window.with_text_style(style.text_style().cloned(), |window| {
1781                            window.with_content_mask(
1782                                style.overflow_mask(bounds, window.rem_size()),
1783                                |window| {
1784                                    if let Some(hitbox) = hitbox {
1785                                        #[cfg(debug_assertions)]
1786                                        self.paint_debug_info(
1787                                            global_id, hitbox, &style, window, cx,
1788                                        );
1789
1790                                        if let Some(drag) = cx.active_drag.as_ref() {
1791                                            if let Some(mouse_cursor) = drag.cursor_style {
1792                                                window.set_window_cursor_style(mouse_cursor);
1793                                            }
1794                                        } else {
1795                                            if let Some(mouse_cursor) = style.mouse_cursor {
1796                                                window.set_cursor_style(mouse_cursor, hitbox);
1797                                            }
1798                                        }
1799
1800                                        if let Some(group) = self.group.clone() {
1801                                            GroupHitboxes::push(group, hitbox.id, cx);
1802                                        }
1803
1804                                        if let Some(area) = self.window_control {
1805                                            window
1806                                                .insert_window_control_hitbox(area, hitbox.clone());
1807                                        }
1808
1809                                        self.paint_mouse_listeners(
1810                                            hitbox,
1811                                            element_state.as_mut(),
1812                                            window,
1813                                            cx,
1814                                        );
1815                                        self.paint_scroll_listener(hitbox, &style, window, cx);
1816                                    }
1817
1818                                    self.paint_keyboard_listeners(window, cx);
1819                                    f(&style, window, cx);
1820
1821                                    if let Some(_hitbox) = hitbox {
1822                                        #[cfg(any(feature = "inspector", debug_assertions))]
1823                                        window.insert_inspector_hitbox(
1824                                            _hitbox.id,
1825                                            _inspector_id,
1826                                            cx,
1827                                        );
1828
1829                                        if let Some(group) = self.group.as_ref() {
1830                                            GroupHitboxes::pop(group, cx);
1831                                        }
1832                                    }
1833                                },
1834                            );
1835                        });
1836                    });
1837                });
1838
1839                ((), element_state)
1840            },
1841        );
1842    }
1843
1844    #[cfg(debug_assertions)]
1845    fn paint_debug_info(
1846        &self,
1847        global_id: Option<&GlobalElementId>,
1848        hitbox: &Hitbox,
1849        style: &Style,
1850        window: &mut Window,
1851        cx: &mut App,
1852    ) {
1853        use crate::{BorderStyle, TextAlign};
1854
1855        if global_id.is_some()
1856            && (style.debug || style.debug_below || cx.has_global::<crate::DebugBelow>())
1857            && hitbox.is_hovered(window)
1858        {
1859            const FONT_SIZE: crate::Pixels = crate::Pixels(10.);
1860            let element_id = format!("{:?}", global_id.unwrap());
1861            let str_len = element_id.len();
1862
1863            let render_debug_text = |window: &mut Window| {
1864                if let Some(text) = window
1865                    .text_system()
1866                    .shape_text(
1867                        element_id.into(),
1868                        FONT_SIZE,
1869                        &[window.text_style().to_run(str_len)],
1870                        None,
1871                        None,
1872                    )
1873                    .ok()
1874                    .and_then(|mut text| text.pop())
1875                {
1876                    text.paint(hitbox.origin, FONT_SIZE, TextAlign::Left, None, window, cx)
1877                        .ok();
1878
1879                    let text_bounds = crate::Bounds {
1880                        origin: hitbox.origin,
1881                        size: text.size(FONT_SIZE),
1882                    };
1883                    if self.source_location.is_some()
1884                        && text_bounds.contains(&window.mouse_position())
1885                        && window.modifiers().secondary()
1886                    {
1887                        let secondary_held = window.modifiers().secondary();
1888                        window.on_key_event({
1889                            move |e: &crate::ModifiersChangedEvent, _phase, window, _cx| {
1890                                if e.modifiers.secondary() != secondary_held
1891                                    && text_bounds.contains(&window.mouse_position())
1892                                {
1893                                    window.refresh();
1894                                }
1895                            }
1896                        });
1897
1898                        let was_hovered = hitbox.is_hovered(window);
1899                        let current_view = window.current_view();
1900                        window.on_mouse_event({
1901                            let hitbox = hitbox.clone();
1902                            move |_: &MouseMoveEvent, phase, window, cx| {
1903                                if phase == DispatchPhase::Capture {
1904                                    let hovered = hitbox.is_hovered(window);
1905                                    if hovered != was_hovered {
1906                                        cx.notify(current_view)
1907                                    }
1908                                }
1909                            }
1910                        });
1911
1912                        window.on_mouse_event({
1913                            let hitbox = hitbox.clone();
1914                            let location = self.source_location.unwrap();
1915                            move |e: &crate::MouseDownEvent, phase, window, cx| {
1916                                if text_bounds.contains(&e.position)
1917                                    && phase.capture()
1918                                    && hitbox.is_hovered(window)
1919                                {
1920                                    cx.stop_propagation();
1921                                    let Ok(dir) = std::env::current_dir() else {
1922                                        return;
1923                                    };
1924
1925                                    eprintln!(
1926                                        "This element was created at:\n{}:{}:{}",
1927                                        dir.join(location.file()).to_string_lossy(),
1928                                        location.line(),
1929                                        location.column()
1930                                    );
1931                                }
1932                            }
1933                        });
1934                        window.paint_quad(crate::outline(
1935                            crate::Bounds {
1936                                origin: hitbox.origin
1937                                    + crate::point(crate::px(0.), FONT_SIZE - px(2.)),
1938                                size: crate::Size {
1939                                    width: text_bounds.size.width,
1940                                    height: crate::px(1.),
1941                                },
1942                            },
1943                            crate::red(),
1944                            BorderStyle::default(),
1945                        ))
1946                    }
1947                }
1948            };
1949
1950            window.with_text_style(
1951                Some(crate::TextStyleRefinement {
1952                    color: Some(crate::red()),
1953                    line_height: Some(FONT_SIZE.into()),
1954                    background_color: Some(crate::white()),
1955                    ..Default::default()
1956                }),
1957                render_debug_text,
1958            )
1959        }
1960    }
1961
1962    fn paint_mouse_listeners(
1963        &mut self,
1964        hitbox: &Hitbox,
1965        element_state: Option<&mut InteractiveElementState>,
1966        window: &mut Window,
1967        cx: &mut App,
1968    ) {
1969        let is_focused = self
1970            .tracked_focus_handle
1971            .as_ref()
1972            .map(|handle| handle.is_focused(window))
1973            .unwrap_or(false);
1974
1975        // If this element can be focused, register a mouse down listener
1976        // that will automatically transfer focus when hitting the element.
1977        // This behavior can be suppressed by using `cx.prevent_default()`.
1978        if let Some(focus_handle) = self.tracked_focus_handle.clone() {
1979            let hitbox = hitbox.clone();
1980            window.on_mouse_event(move |_: &MouseDownEvent, phase, window, _| {
1981                if phase == DispatchPhase::Bubble
1982                    && hitbox.is_hovered(window)
1983                    && !window.default_prevented()
1984                {
1985                    window.focus(&focus_handle);
1986                    // If there is a parent that is also focusable, prevent it
1987                    // from transferring focus because we already did so.
1988                    window.prevent_default();
1989                }
1990            });
1991        }
1992
1993        for listener in self.mouse_down_listeners.drain(..) {
1994            let hitbox = hitbox.clone();
1995            window.on_mouse_event(move |event: &MouseDownEvent, phase, window, cx| {
1996                listener(event, phase, &hitbox, window, cx);
1997            })
1998        }
1999
2000        for listener in self.mouse_up_listeners.drain(..) {
2001            let hitbox = hitbox.clone();
2002            window.on_mouse_event(move |event: &MouseUpEvent, phase, window, cx| {
2003                listener(event, phase, &hitbox, window, cx);
2004            })
2005        }
2006
2007        for listener in self.mouse_move_listeners.drain(..) {
2008            let hitbox = hitbox.clone();
2009            window.on_mouse_event(move |event: &MouseMoveEvent, phase, window, cx| {
2010                listener(event, phase, &hitbox, window, cx);
2011            })
2012        }
2013
2014        for listener in self.scroll_wheel_listeners.drain(..) {
2015            let hitbox = hitbox.clone();
2016            window.on_mouse_event(move |event: &ScrollWheelEvent, phase, window, cx| {
2017                listener(event, phase, &hitbox, window, cx);
2018            })
2019        }
2020
2021        if self.hover_style.is_some()
2022            || self.base_style.mouse_cursor.is_some()
2023            || cx.active_drag.is_some() && !self.drag_over_styles.is_empty()
2024        {
2025            let hitbox = hitbox.clone();
2026            let was_hovered = hitbox.is_hovered(window);
2027            let current_view = window.current_view();
2028            window.on_mouse_event(move |_: &MouseMoveEvent, phase, window, cx| {
2029                let hovered = hitbox.is_hovered(window);
2030                if phase == DispatchPhase::Capture && hovered != was_hovered {
2031                    cx.notify(current_view);
2032                }
2033            });
2034        }
2035        let drag_cursor_style = self.base_style.as_ref().mouse_cursor;
2036
2037        let mut drag_listener = mem::take(&mut self.drag_listener);
2038        let drop_listeners = mem::take(&mut self.drop_listeners);
2039        let click_listeners = mem::take(&mut self.click_listeners);
2040        let can_drop_predicate = mem::take(&mut self.can_drop_predicate);
2041
2042        if !drop_listeners.is_empty() {
2043            let hitbox = hitbox.clone();
2044            window.on_mouse_event({
2045                move |_: &MouseUpEvent, phase, window, cx| {
2046                    if let Some(drag) = &cx.active_drag {
2047                        if phase == DispatchPhase::Bubble && hitbox.is_hovered(window) {
2048                            let drag_state_type = drag.value.as_ref().type_id();
2049                            for (drop_state_type, listener) in &drop_listeners {
2050                                if *drop_state_type == drag_state_type {
2051                                    let drag = cx
2052                                        .active_drag
2053                                        .take()
2054                                        .expect("checked for type drag state type above");
2055
2056                                    let mut can_drop = true;
2057                                    if let Some(predicate) = &can_drop_predicate {
2058                                        can_drop = predicate(drag.value.as_ref(), window, cx);
2059                                    }
2060
2061                                    if can_drop {
2062                                        listener(drag.value.as_ref(), window, cx);
2063                                        window.refresh();
2064                                        cx.stop_propagation();
2065                                    }
2066                                }
2067                            }
2068                        }
2069                    }
2070                }
2071            });
2072        }
2073
2074        if let Some(element_state) = element_state {
2075            if !click_listeners.is_empty() || drag_listener.is_some() {
2076                let pending_mouse_down = element_state
2077                    .pending_mouse_down
2078                    .get_or_insert_with(Default::default)
2079                    .clone();
2080
2081                let clicked_state = element_state
2082                    .clicked_state
2083                    .get_or_insert_with(Default::default)
2084                    .clone();
2085
2086                window.on_mouse_event({
2087                    let pending_mouse_down = pending_mouse_down.clone();
2088                    let hitbox = hitbox.clone();
2089                    move |event: &MouseDownEvent, phase, window, _cx| {
2090                        if phase == DispatchPhase::Bubble
2091                            && event.button == MouseButton::Left
2092                            && hitbox.is_hovered(window)
2093                        {
2094                            *pending_mouse_down.borrow_mut() = Some(event.clone());
2095                            window.refresh();
2096                        }
2097                    }
2098                });
2099
2100                window.on_mouse_event({
2101                    let pending_mouse_down = pending_mouse_down.clone();
2102                    let hitbox = hitbox.clone();
2103                    move |event: &MouseMoveEvent, phase, window, cx| {
2104                        if phase == DispatchPhase::Capture {
2105                            return;
2106                        }
2107
2108                        let mut pending_mouse_down = pending_mouse_down.borrow_mut();
2109                        if let Some(mouse_down) = pending_mouse_down.clone() {
2110                            if !cx.has_active_drag()
2111                                && (event.position - mouse_down.position).magnitude()
2112                                    > DRAG_THRESHOLD
2113                            {
2114                                if let Some((drag_value, drag_listener)) = drag_listener.take() {
2115                                    *clicked_state.borrow_mut() = ElementClickedState::default();
2116                                    let cursor_offset = event.position - hitbox.origin;
2117                                    let drag = (drag_listener)(
2118                                        drag_value.as_ref(),
2119                                        cursor_offset,
2120                                        window,
2121                                        cx,
2122                                    );
2123                                    cx.active_drag = Some(AnyDrag {
2124                                        view: drag,
2125                                        value: drag_value,
2126                                        cursor_offset,
2127                                        cursor_style: drag_cursor_style,
2128                                    });
2129                                    pending_mouse_down.take();
2130                                    window.refresh();
2131                                    cx.stop_propagation();
2132                                }
2133                            }
2134                        }
2135                    }
2136                });
2137
2138                if is_focused {
2139                    // Press enter, space to trigger click, when the element is focused.
2140                    window.on_key_event({
2141                        let click_listeners = click_listeners.clone();
2142                        let hitbox = hitbox.clone();
2143                        move |event: &KeyUpEvent, phase, window, cx| {
2144                            if phase.bubble() && !window.default_prevented() {
2145                                let stroke = &event.keystroke;
2146                                let keyboard_button = if stroke.key.eq("enter") {
2147                                    Some(KeyboardButton::Enter)
2148                                } else if stroke.key.eq("space") {
2149                                    Some(KeyboardButton::Space)
2150                                } else {
2151                                    None
2152                                };
2153
2154                                if let Some(button) = keyboard_button
2155                                    && !stroke.modifiers.modified()
2156                                {
2157                                    let click_event = ClickEvent::Keyboard(KeyboardClickEvent {
2158                                        button,
2159                                        bounds: hitbox.bounds,
2160                                    });
2161
2162                                    for listener in &click_listeners {
2163                                        listener(&click_event, window, cx);
2164                                    }
2165                                }
2166                            }
2167                        }
2168                    });
2169                }
2170
2171                window.on_mouse_event({
2172                    let mut captured_mouse_down = None;
2173                    let hitbox = hitbox.clone();
2174                    move |event: &MouseUpEvent, phase, window, cx| match phase {
2175                        // Clear the pending mouse down during the capture phase,
2176                        // so that it happens even if another event handler stops
2177                        // propagation.
2178                        DispatchPhase::Capture => {
2179                            let mut pending_mouse_down = pending_mouse_down.borrow_mut();
2180                            if pending_mouse_down.is_some() && hitbox.is_hovered(window) {
2181                                captured_mouse_down = pending_mouse_down.take();
2182                                window.refresh();
2183                            } else if pending_mouse_down.is_some() {
2184                                // Clear the pending mouse down event (without firing click handlers)
2185                                // if the hitbox is not being hovered.
2186                                // This avoids dragging elements that changed their position
2187                                // immediately after being clicked.
2188                                // See https://github.com/zed-industries/zed/issues/24600 for more details
2189                                pending_mouse_down.take();
2190                                window.refresh();
2191                            }
2192                        }
2193                        // Fire click handlers during the bubble phase.
2194                        DispatchPhase::Bubble => {
2195                            if let Some(mouse_down) = captured_mouse_down.take() {
2196                                let mouse_click = ClickEvent::Mouse(MouseClickEvent {
2197                                    down: mouse_down,
2198                                    up: event.clone(),
2199                                });
2200                                for listener in &click_listeners {
2201                                    listener(&mouse_click, window, cx);
2202                                }
2203                            }
2204                        }
2205                    }
2206                });
2207            }
2208
2209            if let Some(hover_listener) = self.hover_listener.take() {
2210                let hitbox = hitbox.clone();
2211                let was_hovered = element_state
2212                    .hover_state
2213                    .get_or_insert_with(Default::default)
2214                    .clone();
2215                let has_mouse_down = element_state
2216                    .pending_mouse_down
2217                    .get_or_insert_with(Default::default)
2218                    .clone();
2219
2220                window.on_mouse_event(move |_: &MouseMoveEvent, phase, window, cx| {
2221                    if phase != DispatchPhase::Bubble {
2222                        return;
2223                    }
2224                    let is_hovered = has_mouse_down.borrow().is_none()
2225                        && !cx.has_active_drag()
2226                        && hitbox.is_hovered(window);
2227                    let mut was_hovered = was_hovered.borrow_mut();
2228
2229                    if is_hovered != *was_hovered {
2230                        *was_hovered = is_hovered;
2231                        drop(was_hovered);
2232
2233                        hover_listener(&is_hovered, window, cx);
2234                    }
2235                });
2236            }
2237
2238            if let Some(tooltip_builder) = self.tooltip_builder.take() {
2239                let active_tooltip = element_state
2240                    .active_tooltip
2241                    .get_or_insert_with(Default::default)
2242                    .clone();
2243                let pending_mouse_down = element_state
2244                    .pending_mouse_down
2245                    .get_or_insert_with(Default::default)
2246                    .clone();
2247
2248                let tooltip_is_hoverable = tooltip_builder.hoverable;
2249                let build_tooltip = Rc::new(move |window: &mut Window, cx: &mut App| {
2250                    Some(((tooltip_builder.build)(window, cx), tooltip_is_hoverable))
2251                });
2252                // Use bounds instead of testing hitbox since this is called during prepaint.
2253                let check_is_hovered_during_prepaint = Rc::new({
2254                    let pending_mouse_down = pending_mouse_down.clone();
2255                    let source_bounds = hitbox.bounds;
2256                    move |window: &Window| {
2257                        pending_mouse_down.borrow().is_none()
2258                            && source_bounds.contains(&window.mouse_position())
2259                    }
2260                });
2261                let check_is_hovered = Rc::new({
2262                    let hitbox = hitbox.clone();
2263                    move |window: &Window| {
2264                        pending_mouse_down.borrow().is_none() && hitbox.is_hovered(window)
2265                    }
2266                });
2267                register_tooltip_mouse_handlers(
2268                    &active_tooltip,
2269                    self.tooltip_id,
2270                    build_tooltip,
2271                    check_is_hovered,
2272                    check_is_hovered_during_prepaint,
2273                    window,
2274                );
2275            }
2276
2277            let active_state = element_state
2278                .clicked_state
2279                .get_or_insert_with(Default::default)
2280                .clone();
2281            if active_state.borrow().is_clicked() {
2282                window.on_mouse_event(move |_: &MouseUpEvent, phase, window, _cx| {
2283                    if phase == DispatchPhase::Capture {
2284                        *active_state.borrow_mut() = ElementClickedState::default();
2285                        window.refresh();
2286                    }
2287                });
2288            } else {
2289                let active_group_hitbox = self
2290                    .group_active_style
2291                    .as_ref()
2292                    .and_then(|group_active| GroupHitboxes::get(&group_active.group, cx));
2293                let hitbox = hitbox.clone();
2294                window.on_mouse_event(move |_: &MouseDownEvent, phase, window, _cx| {
2295                    if phase == DispatchPhase::Bubble && !window.default_prevented() {
2296                        let group_hovered = active_group_hitbox
2297                            .map_or(false, |group_hitbox_id| group_hitbox_id.is_hovered(window));
2298                        let element_hovered = hitbox.is_hovered(window);
2299                        if group_hovered || element_hovered {
2300                            *active_state.borrow_mut() = ElementClickedState {
2301                                group: group_hovered,
2302                                element: element_hovered,
2303                            };
2304                            window.refresh();
2305                        }
2306                    }
2307                });
2308            }
2309        }
2310    }
2311
2312    fn paint_keyboard_listeners(&mut self, window: &mut Window, _cx: &mut App) {
2313        let key_down_listeners = mem::take(&mut self.key_down_listeners);
2314        let key_up_listeners = mem::take(&mut self.key_up_listeners);
2315        let modifiers_changed_listeners = mem::take(&mut self.modifiers_changed_listeners);
2316        let action_listeners = mem::take(&mut self.action_listeners);
2317        if let Some(context) = self.key_context.clone() {
2318            window.set_key_context(context);
2319        }
2320
2321        for listener in key_down_listeners {
2322            window.on_key_event(move |event: &KeyDownEvent, phase, window, cx| {
2323                listener(event, phase, window, cx);
2324            })
2325        }
2326
2327        for listener in key_up_listeners {
2328            window.on_key_event(move |event: &KeyUpEvent, phase, window, cx| {
2329                listener(event, phase, window, cx);
2330            })
2331        }
2332
2333        for listener in modifiers_changed_listeners {
2334            window.on_modifiers_changed(move |event: &ModifiersChangedEvent, window, cx| {
2335                listener(event, window, cx);
2336            })
2337        }
2338
2339        for (action_type, listener) in action_listeners {
2340            window.on_action(action_type, listener)
2341        }
2342    }
2343
2344    fn paint_hover_group_handler(&self, window: &mut Window, cx: &mut App) {
2345        let group_hitbox = self
2346            .group_hover_style
2347            .as_ref()
2348            .and_then(|group_hover| GroupHitboxes::get(&group_hover.group, cx));
2349
2350        if let Some(group_hitbox) = group_hitbox {
2351            let was_hovered = group_hitbox.is_hovered(window);
2352            let current_view = window.current_view();
2353            window.on_mouse_event(move |_: &MouseMoveEvent, phase, window, cx| {
2354                let hovered = group_hitbox.is_hovered(window);
2355                if phase == DispatchPhase::Capture && hovered != was_hovered {
2356                    cx.notify(current_view);
2357                }
2358            });
2359        }
2360    }
2361
2362    fn paint_scroll_listener(
2363        &self,
2364        hitbox: &Hitbox,
2365        style: &Style,
2366        window: &mut Window,
2367        _cx: &mut App,
2368    ) {
2369        if let Some(scroll_offset) = self.scroll_offset.clone() {
2370            let overflow = style.overflow;
2371            let allow_concurrent_scroll = style.allow_concurrent_scroll;
2372            let restrict_scroll_to_axis = style.restrict_scroll_to_axis;
2373            let line_height = window.line_height();
2374            let hitbox = hitbox.clone();
2375            let current_view = window.current_view();
2376            window.on_mouse_event(move |event: &ScrollWheelEvent, phase, window, cx| {
2377                if phase == DispatchPhase::Bubble && hitbox.should_handle_scroll(window) {
2378                    let mut scroll_offset = scroll_offset.borrow_mut();
2379                    let old_scroll_offset = *scroll_offset;
2380                    let delta = event.delta.pixel_delta(line_height);
2381
2382                    let mut delta_x = Pixels::ZERO;
2383                    if overflow.x == Overflow::Scroll {
2384                        if !delta.x.is_zero() {
2385                            delta_x = delta.x;
2386                        } else if !restrict_scroll_to_axis && overflow.y != Overflow::Scroll {
2387                            delta_x = delta.y;
2388                        }
2389                    }
2390                    let mut delta_y = Pixels::ZERO;
2391                    if overflow.y == Overflow::Scroll {
2392                        if !delta.y.is_zero() {
2393                            delta_y = delta.y;
2394                        } else if !restrict_scroll_to_axis && overflow.x != Overflow::Scroll {
2395                            delta_y = delta.x;
2396                        }
2397                    }
2398                    if !allow_concurrent_scroll && !delta_x.is_zero() && !delta_y.is_zero() {
2399                        if delta_x.abs() > delta_y.abs() {
2400                            delta_y = Pixels::ZERO;
2401                        } else {
2402                            delta_x = Pixels::ZERO;
2403                        }
2404                    }
2405                    scroll_offset.y += delta_y;
2406                    scroll_offset.x += delta_x;
2407                    if *scroll_offset != old_scroll_offset {
2408                        cx.notify(current_view);
2409                    }
2410                }
2411            });
2412        }
2413    }
2414
2415    /// Compute the visual style for this element, based on the current bounds and the element's state.
2416    pub fn compute_style(
2417        &self,
2418        global_id: Option<&GlobalElementId>,
2419        hitbox: Option<&Hitbox>,
2420        window: &mut Window,
2421        cx: &mut App,
2422    ) -> Style {
2423        window.with_optional_element_state(global_id, |element_state, window| {
2424            let mut element_state =
2425                element_state.map(|element_state| element_state.unwrap_or_default());
2426            let style = self.compute_style_internal(hitbox, element_state.as_mut(), window, cx);
2427            (style, element_state)
2428        })
2429    }
2430
2431    /// Called from internal methods that have already called with_element_state.
2432    fn compute_style_internal(
2433        &self,
2434        hitbox: Option<&Hitbox>,
2435        element_state: Option<&mut InteractiveElementState>,
2436        window: &mut Window,
2437        cx: &mut App,
2438    ) -> Style {
2439        let mut style = Style::default();
2440        style.refine(&self.base_style);
2441
2442        if let Some(focus_handle) = self.tracked_focus_handle.as_ref() {
2443            if let Some(in_focus_style) = self.in_focus_style.as_ref() {
2444                if focus_handle.within_focused(window, cx) {
2445                    style.refine(in_focus_style);
2446                }
2447            }
2448
2449            if let Some(focus_style) = self.focus_style.as_ref() {
2450                if focus_handle.is_focused(window) {
2451                    style.refine(focus_style);
2452                }
2453            }
2454        }
2455
2456        if let Some(hitbox) = hitbox {
2457            if !cx.has_active_drag() {
2458                if let Some(group_hover) = self.group_hover_style.as_ref() {
2459                    if let Some(group_hitbox_id) = GroupHitboxes::get(&group_hover.group, cx) {
2460                        if group_hitbox_id.is_hovered(window) {
2461                            style.refine(&group_hover.style);
2462                        }
2463                    }
2464                }
2465
2466                if let Some(hover_style) = self.hover_style.as_ref() {
2467                    if hitbox.is_hovered(window) {
2468                        style.refine(hover_style);
2469                    }
2470                }
2471            }
2472
2473            if let Some(drag) = cx.active_drag.take() {
2474                let mut can_drop = true;
2475                if let Some(can_drop_predicate) = &self.can_drop_predicate {
2476                    can_drop = can_drop_predicate(drag.value.as_ref(), window, cx);
2477                }
2478
2479                if can_drop {
2480                    for (state_type, group_drag_style) in &self.group_drag_over_styles {
2481                        if let Some(group_hitbox_id) =
2482                            GroupHitboxes::get(&group_drag_style.group, cx)
2483                        {
2484                            if *state_type == drag.value.as_ref().type_id()
2485                                && group_hitbox_id.is_hovered(window)
2486                            {
2487                                style.refine(&group_drag_style.style);
2488                            }
2489                        }
2490                    }
2491
2492                    for (state_type, build_drag_over_style) in &self.drag_over_styles {
2493                        if *state_type == drag.value.as_ref().type_id() && hitbox.is_hovered(window)
2494                        {
2495                            style.refine(&build_drag_over_style(drag.value.as_ref(), window, cx));
2496                        }
2497                    }
2498                }
2499
2500                style.mouse_cursor = drag.cursor_style;
2501                cx.active_drag = Some(drag);
2502            }
2503        }
2504
2505        if let Some(element_state) = element_state {
2506            let clicked_state = element_state
2507                .clicked_state
2508                .get_or_insert_with(Default::default)
2509                .borrow();
2510            if clicked_state.group {
2511                if let Some(group) = self.group_active_style.as_ref() {
2512                    style.refine(&group.style)
2513                }
2514            }
2515
2516            if let Some(active_style) = self.active_style.as_ref() {
2517                if clicked_state.element {
2518                    style.refine(active_style)
2519                }
2520            }
2521        }
2522
2523        style
2524    }
2525}
2526
2527/// The per-frame state of an interactive element. Used for tracking stateful interactions like clicks
2528/// and scroll offsets.
2529#[derive(Default)]
2530pub struct InteractiveElementState {
2531    pub(crate) focus_handle: Option<FocusHandle>,
2532    pub(crate) clicked_state: Option<Rc<RefCell<ElementClickedState>>>,
2533    pub(crate) hover_state: Option<Rc<RefCell<bool>>>,
2534    pub(crate) pending_mouse_down: Option<Rc<RefCell<Option<MouseDownEvent>>>>,
2535    pub(crate) scroll_offset: Option<Rc<RefCell<Point<Pixels>>>>,
2536    pub(crate) active_tooltip: Option<Rc<RefCell<Option<ActiveTooltip>>>>,
2537}
2538
2539/// Whether or not the element or a group that contains it is clicked by the mouse.
2540#[derive(Copy, Clone, Default, Eq, PartialEq)]
2541pub struct ElementClickedState {
2542    /// True if this element's group has been clicked, false otherwise
2543    pub group: bool,
2544
2545    /// True if this element has been clicked, false otherwise
2546    pub element: bool,
2547}
2548
2549impl ElementClickedState {
2550    fn is_clicked(&self) -> bool {
2551        self.group || self.element
2552    }
2553}
2554
2555pub(crate) enum ActiveTooltip {
2556    /// Currently delaying before showing the tooltip.
2557    WaitingForShow { _task: Task<()> },
2558    /// Tooltip is visible, element was hovered or for hoverable tooltips, the tooltip was hovered.
2559    Visible {
2560        tooltip: AnyTooltip,
2561        is_hoverable: bool,
2562    },
2563    /// Tooltip is visible and hoverable, but the mouse is no longer hovering. Currently delaying
2564    /// before hiding it.
2565    WaitingForHide {
2566        tooltip: AnyTooltip,
2567        _task: Task<()>,
2568    },
2569}
2570
2571pub(crate) fn clear_active_tooltip(
2572    active_tooltip: &Rc<RefCell<Option<ActiveTooltip>>>,
2573    window: &mut Window,
2574) {
2575    match active_tooltip.borrow_mut().take() {
2576        None => {}
2577        Some(ActiveTooltip::WaitingForShow { .. }) => {}
2578        Some(ActiveTooltip::Visible { .. }) => window.refresh(),
2579        Some(ActiveTooltip::WaitingForHide { .. }) => window.refresh(),
2580    }
2581}
2582
2583pub(crate) fn clear_active_tooltip_if_not_hoverable(
2584    active_tooltip: &Rc<RefCell<Option<ActiveTooltip>>>,
2585    window: &mut Window,
2586) {
2587    let should_clear = match active_tooltip.borrow().as_ref() {
2588        None => false,
2589        Some(ActiveTooltip::WaitingForShow { .. }) => false,
2590        Some(ActiveTooltip::Visible { is_hoverable, .. }) => !is_hoverable,
2591        Some(ActiveTooltip::WaitingForHide { .. }) => false,
2592    };
2593    if should_clear {
2594        active_tooltip.borrow_mut().take();
2595        window.refresh();
2596    }
2597}
2598
2599pub(crate) fn set_tooltip_on_window(
2600    active_tooltip: &Rc<RefCell<Option<ActiveTooltip>>>,
2601    window: &mut Window,
2602) -> Option<TooltipId> {
2603    let tooltip = match active_tooltip.borrow().as_ref() {
2604        None => return None,
2605        Some(ActiveTooltip::WaitingForShow { .. }) => return None,
2606        Some(ActiveTooltip::Visible { tooltip, .. }) => tooltip.clone(),
2607        Some(ActiveTooltip::WaitingForHide { tooltip, .. }) => tooltip.clone(),
2608    };
2609    Some(window.set_tooltip(tooltip))
2610}
2611
2612pub(crate) fn register_tooltip_mouse_handlers(
2613    active_tooltip: &Rc<RefCell<Option<ActiveTooltip>>>,
2614    tooltip_id: Option<TooltipId>,
2615    build_tooltip: Rc<dyn Fn(&mut Window, &mut App) -> Option<(AnyView, bool)>>,
2616    check_is_hovered: Rc<dyn Fn(&Window) -> bool>,
2617    check_is_hovered_during_prepaint: Rc<dyn Fn(&Window) -> bool>,
2618    window: &mut Window,
2619) {
2620    window.on_mouse_event({
2621        let active_tooltip = active_tooltip.clone();
2622        let build_tooltip = build_tooltip.clone();
2623        let check_is_hovered = check_is_hovered.clone();
2624        move |_: &MouseMoveEvent, phase, window, cx| {
2625            handle_tooltip_mouse_move(
2626                &active_tooltip,
2627                &build_tooltip,
2628                &check_is_hovered,
2629                &check_is_hovered_during_prepaint,
2630                phase,
2631                window,
2632                cx,
2633            )
2634        }
2635    });
2636
2637    window.on_mouse_event({
2638        let active_tooltip = active_tooltip.clone();
2639        move |_: &MouseDownEvent, _phase, window: &mut Window, _cx| {
2640            if !tooltip_id.map_or(false, |tooltip_id| tooltip_id.is_hovered(window)) {
2641                clear_active_tooltip_if_not_hoverable(&active_tooltip, window);
2642            }
2643        }
2644    });
2645
2646    window.on_mouse_event({
2647        let active_tooltip = active_tooltip.clone();
2648        move |_: &ScrollWheelEvent, _phase, window: &mut Window, _cx| {
2649            if !tooltip_id.map_or(false, |tooltip_id| tooltip_id.is_hovered(window)) {
2650                clear_active_tooltip_if_not_hoverable(&active_tooltip, window);
2651            }
2652        }
2653    });
2654}
2655
2656/// Handles displaying tooltips when an element is hovered.
2657///
2658/// The mouse hovering logic also relies on being called from window prepaint in order to handle the
2659/// case where the element the tooltip is on is not rendered - in that case its mouse listeners are
2660/// also not registered. During window prepaint, the hitbox information is not available, so
2661/// `check_is_hovered_during_prepaint` is used which bases the check off of the absolute bounds of
2662/// the element.
2663///
2664/// TODO: There's a minor bug due to the use of absolute bounds while checking during prepaint - it
2665/// does not know if the hitbox is occluded. In the case where a tooltip gets displayed and then
2666/// gets occluded after display, it will stick around until the mouse exits the hover bounds.
2667fn handle_tooltip_mouse_move(
2668    active_tooltip: &Rc<RefCell<Option<ActiveTooltip>>>,
2669    build_tooltip: &Rc<dyn Fn(&mut Window, &mut App) -> Option<(AnyView, bool)>>,
2670    check_is_hovered: &Rc<dyn Fn(&Window) -> bool>,
2671    check_is_hovered_during_prepaint: &Rc<dyn Fn(&Window) -> bool>,
2672    phase: DispatchPhase,
2673    window: &mut Window,
2674    cx: &mut App,
2675) {
2676    // Separates logic for what mutation should occur from applying it, to avoid overlapping
2677    // RefCell borrows.
2678    enum Action {
2679        None,
2680        CancelShow,
2681        ScheduleShow,
2682    }
2683
2684    let action = match active_tooltip.borrow().as_ref() {
2685        None => {
2686            let is_hovered = check_is_hovered(window);
2687            if is_hovered && phase.bubble() {
2688                Action::ScheduleShow
2689            } else {
2690                Action::None
2691            }
2692        }
2693        Some(ActiveTooltip::WaitingForShow { .. }) => {
2694            let is_hovered = check_is_hovered(window);
2695            if is_hovered {
2696                Action::None
2697            } else {
2698                Action::CancelShow
2699            }
2700        }
2701        // These are handled in check_visible_and_update.
2702        Some(ActiveTooltip::Visible { .. }) | Some(ActiveTooltip::WaitingForHide { .. }) => {
2703            Action::None
2704        }
2705    };
2706
2707    match action {
2708        Action::None => {}
2709        Action::CancelShow => {
2710            // Cancel waiting to show tooltip when it is no longer hovered.
2711            active_tooltip.borrow_mut().take();
2712        }
2713        Action::ScheduleShow => {
2714            let delayed_show_task = window.spawn(cx, {
2715                let active_tooltip = active_tooltip.clone();
2716                let build_tooltip = build_tooltip.clone();
2717                let check_is_hovered_during_prepaint = check_is_hovered_during_prepaint.clone();
2718                async move |cx| {
2719                    cx.background_executor().timer(TOOLTIP_SHOW_DELAY).await;
2720                    cx.update(|window, cx| {
2721                        let new_tooltip =
2722                            build_tooltip(window, cx).map(|(view, tooltip_is_hoverable)| {
2723                                let active_tooltip = active_tooltip.clone();
2724                                ActiveTooltip::Visible {
2725                                    tooltip: AnyTooltip {
2726                                        view,
2727                                        mouse_position: window.mouse_position(),
2728                                        check_visible_and_update: Rc::new(
2729                                            move |tooltip_bounds, window, cx| {
2730                                                handle_tooltip_check_visible_and_update(
2731                                                    &active_tooltip,
2732                                                    tooltip_is_hoverable,
2733                                                    &check_is_hovered_during_prepaint,
2734                                                    tooltip_bounds,
2735                                                    window,
2736                                                    cx,
2737                                                )
2738                                            },
2739                                        ),
2740                                    },
2741                                    is_hoverable: tooltip_is_hoverable,
2742                                }
2743                            });
2744                        *active_tooltip.borrow_mut() = new_tooltip;
2745                        window.refresh();
2746                    })
2747                    .ok();
2748                }
2749            });
2750            active_tooltip
2751                .borrow_mut()
2752                .replace(ActiveTooltip::WaitingForShow {
2753                    _task: delayed_show_task,
2754                });
2755        }
2756    }
2757}
2758
2759/// Returns a callback which will be called by window prepaint to update tooltip visibility. The
2760/// purpose of doing this logic here instead of the mouse move handler is that the mouse move
2761/// handler won't get called when the element is not painted (e.g. via use of `visible_on_hover`).
2762fn handle_tooltip_check_visible_and_update(
2763    active_tooltip: &Rc<RefCell<Option<ActiveTooltip>>>,
2764    tooltip_is_hoverable: bool,
2765    check_is_hovered: &Rc<dyn Fn(&Window) -> bool>,
2766    tooltip_bounds: Bounds<Pixels>,
2767    window: &mut Window,
2768    cx: &mut App,
2769) -> bool {
2770    // Separates logic for what mutation should occur from applying it, to avoid overlapping RefCell
2771    // borrows.
2772    enum Action {
2773        None,
2774        Hide,
2775        ScheduleHide(AnyTooltip),
2776        CancelHide(AnyTooltip),
2777    }
2778
2779    let is_hovered = check_is_hovered(window)
2780        || (tooltip_is_hoverable && tooltip_bounds.contains(&window.mouse_position()));
2781    let action = match active_tooltip.borrow().as_ref() {
2782        Some(ActiveTooltip::Visible { tooltip, .. }) => {
2783            if is_hovered {
2784                Action::None
2785            } else {
2786                if tooltip_is_hoverable {
2787                    Action::ScheduleHide(tooltip.clone())
2788                } else {
2789                    Action::Hide
2790                }
2791            }
2792        }
2793        Some(ActiveTooltip::WaitingForHide { tooltip, .. }) => {
2794            if is_hovered {
2795                Action::CancelHide(tooltip.clone())
2796            } else {
2797                Action::None
2798            }
2799        }
2800        None | Some(ActiveTooltip::WaitingForShow { .. }) => Action::None,
2801    };
2802
2803    match action {
2804        Action::None => {}
2805        Action::Hide => clear_active_tooltip(&active_tooltip, window),
2806        Action::ScheduleHide(tooltip) => {
2807            let delayed_hide_task = window.spawn(cx, {
2808                let active_tooltip = active_tooltip.clone();
2809                async move |cx| {
2810                    cx.background_executor()
2811                        .timer(HOVERABLE_TOOLTIP_HIDE_DELAY)
2812                        .await;
2813                    if active_tooltip.borrow_mut().take().is_some() {
2814                        cx.update(|window, _cx| window.refresh()).ok();
2815                    }
2816                }
2817            });
2818            active_tooltip
2819                .borrow_mut()
2820                .replace(ActiveTooltip::WaitingForHide {
2821                    tooltip,
2822                    _task: delayed_hide_task,
2823                });
2824        }
2825        Action::CancelHide(tooltip) => {
2826            // Cancel waiting to hide tooltip when it becomes hovered.
2827            active_tooltip.borrow_mut().replace(ActiveTooltip::Visible {
2828                tooltip,
2829                is_hoverable: true,
2830            });
2831        }
2832    }
2833
2834    active_tooltip.borrow().is_some()
2835}
2836
2837#[derive(Default)]
2838pub(crate) struct GroupHitboxes(HashMap<SharedString, SmallVec<[HitboxId; 1]>>);
2839
2840impl Global for GroupHitboxes {}
2841
2842impl GroupHitboxes {
2843    pub fn get(name: &SharedString, cx: &mut App) -> Option<HitboxId> {
2844        cx.default_global::<Self>()
2845            .0
2846            .get(name)
2847            .and_then(|bounds_stack| bounds_stack.last())
2848            .cloned()
2849    }
2850
2851    pub fn push(name: SharedString, hitbox_id: HitboxId, cx: &mut App) {
2852        cx.default_global::<Self>()
2853            .0
2854            .entry(name)
2855            .or_default()
2856            .push(hitbox_id);
2857    }
2858
2859    pub fn pop(name: &SharedString, cx: &mut App) {
2860        cx.default_global::<Self>().0.get_mut(name).unwrap().pop();
2861    }
2862}
2863
2864/// A wrapper around an element that can store state, produced after assigning an ElementId.
2865pub struct Stateful<E> {
2866    pub(crate) element: E,
2867}
2868
2869impl<E> Styled for Stateful<E>
2870where
2871    E: Styled,
2872{
2873    fn style(&mut self) -> &mut StyleRefinement {
2874        self.element.style()
2875    }
2876}
2877
2878impl<E> StatefulInteractiveElement for Stateful<E>
2879where
2880    E: Element,
2881    Self: InteractiveElement,
2882{
2883}
2884
2885impl<E> InteractiveElement for Stateful<E>
2886where
2887    E: InteractiveElement,
2888{
2889    fn interactivity(&mut self) -> &mut Interactivity {
2890        self.element.interactivity()
2891    }
2892}
2893
2894impl<E> Element for Stateful<E>
2895where
2896    E: Element,
2897{
2898    type RequestLayoutState = E::RequestLayoutState;
2899    type PrepaintState = E::PrepaintState;
2900
2901    fn id(&self) -> Option<ElementId> {
2902        self.element.id()
2903    }
2904
2905    fn source_location(&self) -> Option<&'static core::panic::Location<'static>> {
2906        self.element.source_location()
2907    }
2908
2909    fn request_layout(
2910        &mut self,
2911        id: Option<&GlobalElementId>,
2912        inspector_id: Option<&InspectorElementId>,
2913        window: &mut Window,
2914        cx: &mut App,
2915    ) -> (LayoutId, Self::RequestLayoutState) {
2916        self.element.request_layout(id, inspector_id, window, cx)
2917    }
2918
2919    fn prepaint(
2920        &mut self,
2921        id: Option<&GlobalElementId>,
2922        inspector_id: Option<&InspectorElementId>,
2923        bounds: Bounds<Pixels>,
2924        state: &mut Self::RequestLayoutState,
2925        window: &mut Window,
2926        cx: &mut App,
2927    ) -> E::PrepaintState {
2928        self.element
2929            .prepaint(id, inspector_id, bounds, state, window, cx)
2930    }
2931
2932    fn paint(
2933        &mut self,
2934        id: Option<&GlobalElementId>,
2935        inspector_id: Option<&InspectorElementId>,
2936        bounds: Bounds<Pixels>,
2937        request_layout: &mut Self::RequestLayoutState,
2938        prepaint: &mut Self::PrepaintState,
2939        window: &mut Window,
2940        cx: &mut App,
2941    ) {
2942        self.element.paint(
2943            id,
2944            inspector_id,
2945            bounds,
2946            request_layout,
2947            prepaint,
2948            window,
2949            cx,
2950        );
2951    }
2952}
2953
2954impl<E> IntoElement for Stateful<E>
2955where
2956    E: Element,
2957{
2958    type Element = Self;
2959
2960    fn into_element(self) -> Self::Element {
2961        self
2962    }
2963}
2964
2965impl<E> ParentElement for Stateful<E>
2966where
2967    E: ParentElement,
2968{
2969    fn extend(&mut self, elements: impl IntoIterator<Item = AnyElement>) {
2970        self.element.extend(elements)
2971    }
2972}
2973
2974/// Represents an element that can be scrolled *to* in its parent element.
2975///
2976/// Contrary to [ScrollHandle::scroll_to_item], an anchored element does not have to be an immediate child of the parent.
2977#[derive(Clone)]
2978pub struct ScrollAnchor {
2979    handle: ScrollHandle,
2980    last_origin: Rc<RefCell<Point<Pixels>>>,
2981}
2982
2983impl ScrollAnchor {
2984    /// Creates a [ScrollAnchor] associated with a given [ScrollHandle].
2985    pub fn for_handle(handle: ScrollHandle) -> Self {
2986        Self {
2987            handle,
2988            last_origin: Default::default(),
2989        }
2990    }
2991    /// Request scroll to this item on the next frame.
2992    pub fn scroll_to(&self, window: &mut Window, _cx: &mut App) {
2993        let this = self.clone();
2994
2995        window.on_next_frame(move |_, _| {
2996            let viewport_bounds = this.handle.bounds();
2997            let self_bounds = *this.last_origin.borrow();
2998            this.handle.set_offset(viewport_bounds.origin - self_bounds);
2999        });
3000    }
3001}
3002
3003#[derive(Default, Debug)]
3004struct ScrollHandleState {
3005    offset: Rc<RefCell<Point<Pixels>>>,
3006    bounds: Bounds<Pixels>,
3007    max_offset: Size<Pixels>,
3008    child_bounds: Vec<Bounds<Pixels>>,
3009    scroll_to_bottom: bool,
3010    overflow: Point<Overflow>,
3011}
3012
3013/// A handle to the scrollable aspects of an element.
3014/// Used for accessing scroll state, like the current scroll offset,
3015/// and for mutating the scroll state, like scrolling to a specific child.
3016#[derive(Clone, Debug)]
3017pub struct ScrollHandle(Rc<RefCell<ScrollHandleState>>);
3018
3019impl Default for ScrollHandle {
3020    fn default() -> Self {
3021        Self::new()
3022    }
3023}
3024
3025impl ScrollHandle {
3026    /// Construct a new scroll handle.
3027    pub fn new() -> Self {
3028        Self(Rc::default())
3029    }
3030
3031    /// Get the current scroll offset.
3032    pub fn offset(&self) -> Point<Pixels> {
3033        *self.0.borrow().offset.borrow()
3034    }
3035
3036    /// Get the maximum scroll offset.
3037    pub fn max_offset(&self) -> Size<Pixels> {
3038        self.0.borrow().max_offset
3039    }
3040
3041    /// Get the top child that's scrolled into view.
3042    pub fn top_item(&self) -> usize {
3043        let state = self.0.borrow();
3044        let top = state.bounds.top() - state.offset.borrow().y;
3045
3046        match state.child_bounds.binary_search_by(|bounds| {
3047            if top < bounds.top() {
3048                Ordering::Greater
3049            } else if top > bounds.bottom() {
3050                Ordering::Less
3051            } else {
3052                Ordering::Equal
3053            }
3054        }) {
3055            Ok(ix) => ix,
3056            Err(ix) => ix.min(state.child_bounds.len().saturating_sub(1)),
3057        }
3058    }
3059
3060    /// Return the bounds into which this child is painted
3061    pub fn bounds(&self) -> Bounds<Pixels> {
3062        self.0.borrow().bounds
3063    }
3064
3065    /// Get the bounds for a specific child.
3066    pub fn bounds_for_item(&self, ix: usize) -> Option<Bounds<Pixels>> {
3067        self.0.borrow().child_bounds.get(ix).cloned()
3068    }
3069
3070    /// scroll_to_item scrolls the minimal amount to ensure that the child is
3071    /// fully visible
3072    pub fn scroll_to_item(&self, ix: usize) {
3073        let state = self.0.borrow();
3074
3075        let Some(bounds) = state.child_bounds.get(ix) else {
3076            return;
3077        };
3078
3079        let mut scroll_offset = state.offset.borrow_mut();
3080
3081        if state.overflow.y == Overflow::Scroll {
3082            if bounds.top() + scroll_offset.y < state.bounds.top() {
3083                scroll_offset.y = state.bounds.top() - bounds.top();
3084            } else if bounds.bottom() + scroll_offset.y > state.bounds.bottom() {
3085                scroll_offset.y = state.bounds.bottom() - bounds.bottom();
3086            }
3087        }
3088
3089        if state.overflow.x == Overflow::Scroll {
3090            if bounds.left() + scroll_offset.x < state.bounds.left() {
3091                scroll_offset.x = state.bounds.left() - bounds.left();
3092            } else if bounds.right() + scroll_offset.x > state.bounds.right() {
3093                scroll_offset.x = state.bounds.right() - bounds.right();
3094            }
3095        }
3096    }
3097
3098    /// Scrolls to the bottom.
3099    pub fn scroll_to_bottom(&self) {
3100        let mut state = self.0.borrow_mut();
3101        state.scroll_to_bottom = true;
3102    }
3103
3104    /// Set the offset explicitly. The offset is the distance from the top left of the
3105    /// parent container to the top left of the first child.
3106    /// As you scroll further down the offset becomes more negative.
3107    pub fn set_offset(&self, mut position: Point<Pixels>) {
3108        let state = self.0.borrow();
3109        *state.offset.borrow_mut() = position;
3110    }
3111
3112    /// Get the logical scroll top, based on a child index and a pixel offset.
3113    pub fn logical_scroll_top(&self) -> (usize, Pixels) {
3114        let ix = self.top_item();
3115        let state = self.0.borrow();
3116
3117        if let Some(child_bounds) = state.child_bounds.get(ix) {
3118            (
3119                ix,
3120                child_bounds.top() + state.offset.borrow().y - state.bounds.top(),
3121            )
3122        } else {
3123            (ix, px(0.))
3124        }
3125    }
3126
3127    /// Get the count of children for scrollable item.
3128    pub fn children_count(&self) -> usize {
3129        self.0.borrow().child_bounds.len()
3130    }
3131}