1use crate::{
2 point, px, Action, AnyDrag, AnyElement, AnyTooltip, AnyView, AppContext, BorrowAppContext,
3 BorrowWindow, Bounds, ClickEvent, DispatchPhase, Element, ElementId, FocusEvent, FocusHandle,
4 IntoElement, KeyContext, KeyDownEvent, KeyUpEvent, LayoutId, MouseButton, MouseDownEvent,
5 MouseMoveEvent, MouseUpEvent, ParentElement, Pixels, Point, Render, ScrollWheelEvent,
6 SharedString, Size, StackingOrder, Style, StyleRefinement, Styled, Task, View, Visibility,
7 WindowContext,
8};
9use collections::HashMap;
10use refineable::Refineable;
11use smallvec::SmallVec;
12use std::{
13 any::{Any, TypeId},
14 cell::RefCell,
15 cmp::Ordering,
16 fmt::Debug,
17 mem,
18 rc::Rc,
19 time::Duration,
20};
21use taffy::style::Overflow;
22use util::ResultExt;
23
24const DRAG_THRESHOLD: f64 = 2.;
25const TOOLTIP_DELAY: Duration = Duration::from_millis(500);
26
27pub struct GroupStyle {
28 pub group: SharedString,
29 pub style: StyleRefinement,
30}
31
32pub trait InteractiveElement: Sized + Element {
33 fn interactivity(&mut self) -> &mut Interactivity;
34
35 fn group(mut self, group: impl Into<SharedString>) -> Self {
36 self.interactivity().group = Some(group.into());
37 self
38 }
39
40 fn id(mut self, id: impl Into<ElementId>) -> Stateful<Self> {
41 self.interactivity().element_id = Some(id.into());
42
43 Stateful { element: self }
44 }
45
46 fn track_focus(mut self, focus_handle: &FocusHandle) -> Focusable<Self> {
47 self.interactivity().focusable = true;
48 self.interactivity().tracked_focus_handle = Some(focus_handle.clone());
49 Focusable { element: self }
50 }
51
52 fn key_context<C, E>(mut self, key_context: C) -> Self
53 where
54 C: TryInto<KeyContext, Error = E>,
55 E: Debug,
56 {
57 if let Some(key_context) = key_context.try_into().log_err() {
58 self.interactivity().key_context = Some(key_context);
59 }
60 self
61 }
62
63 fn hover(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self {
64 self.interactivity().hover_style = f(StyleRefinement::default());
65 self
66 }
67
68 fn group_hover(
69 mut self,
70 group_name: impl Into<SharedString>,
71 f: impl FnOnce(StyleRefinement) -> StyleRefinement,
72 ) -> Self {
73 self.interactivity().group_hover_style = Some(GroupStyle {
74 group: group_name.into(),
75 style: f(StyleRefinement::default()),
76 });
77 self
78 }
79
80 fn on_mouse_down(
81 mut self,
82 button: MouseButton,
83 listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
84 ) -> Self {
85 self.interactivity().mouse_down_listeners.push(Box::new(
86 move |event, bounds, phase, cx| {
87 if phase == DispatchPhase::Bubble
88 && event.button == button
89 && bounds.visibly_contains(&event.position, cx)
90 {
91 (listener)(event, cx)
92 }
93 },
94 ));
95 self
96 }
97
98 fn on_any_mouse_down(
99 mut self,
100 listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
101 ) -> Self {
102 self.interactivity().mouse_down_listeners.push(Box::new(
103 move |event, bounds, phase, cx| {
104 if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
105 (listener)(event, cx)
106 }
107 },
108 ));
109 self
110 }
111
112 fn on_mouse_up(
113 mut self,
114 button: MouseButton,
115 listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
116 ) -> Self {
117 self.interactivity()
118 .mouse_up_listeners
119 .push(Box::new(move |event, bounds, phase, cx| {
120 if phase == DispatchPhase::Bubble
121 && event.button == button
122 && bounds.visibly_contains(&event.position, cx)
123 {
124 (listener)(event, cx)
125 }
126 }));
127 self
128 }
129
130 fn on_any_mouse_up(
131 mut self,
132 listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
133 ) -> Self {
134 self.interactivity()
135 .mouse_up_listeners
136 .push(Box::new(move |event, bounds, phase, cx| {
137 if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
138 (listener)(event, cx)
139 }
140 }));
141 self
142 }
143
144 fn on_mouse_down_out(
145 mut self,
146 listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
147 ) -> Self {
148 self.interactivity().mouse_down_listeners.push(Box::new(
149 move |event, bounds, phase, cx| {
150 if phase == DispatchPhase::Capture && !bounds.visibly_contains(&event.position, cx)
151 {
152 (listener)(event, cx)
153 }
154 },
155 ));
156 self
157 }
158
159 fn on_mouse_up_out(
160 mut self,
161 button: MouseButton,
162 listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
163 ) -> Self {
164 self.interactivity()
165 .mouse_up_listeners
166 .push(Box::new(move |event, bounds, phase, cx| {
167 if phase == DispatchPhase::Capture
168 && event.button == button
169 && !bounds.visibly_contains(&event.position, cx)
170 {
171 (listener)(event, cx);
172 }
173 }));
174 self
175 }
176
177 fn on_mouse_move(
178 mut self,
179 listener: impl Fn(&MouseMoveEvent, &mut WindowContext) + 'static,
180 ) -> Self {
181 self.interactivity().mouse_move_listeners.push(Box::new(
182 move |event, bounds, phase, cx| {
183 if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
184 (listener)(event, cx);
185 }
186 },
187 ));
188 self
189 }
190
191 fn on_scroll_wheel(
192 mut self,
193 listener: impl Fn(&ScrollWheelEvent, &mut WindowContext) + 'static,
194 ) -> Self {
195 self.interactivity().scroll_wheel_listeners.push(Box::new(
196 move |event, bounds, phase, cx| {
197 if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
198 (listener)(event, cx);
199 }
200 },
201 ));
202 self
203 }
204
205 /// Capture the given action, before normal action dispatch can fire
206 fn capture_action<A: Action>(
207 mut self,
208 listener: impl Fn(&A, &mut WindowContext) + 'static,
209 ) -> Self {
210 self.interactivity().action_listeners.push((
211 TypeId::of::<A>(),
212 Box::new(move |action, phase, cx| {
213 let action = action.downcast_ref().unwrap();
214 if phase == DispatchPhase::Capture {
215 (listener)(action, cx)
216 }
217 }),
218 ));
219 self
220 }
221
222 /// Add a listener for the given action, fires during the bubble event phase
223 fn on_action<A: Action>(mut self, listener: impl Fn(&A, &mut WindowContext) + 'static) -> Self {
224 self.interactivity().action_listeners.push((
225 TypeId::of::<A>(),
226 Box::new(move |action, phase, cx| {
227 let action = action.downcast_ref().unwrap();
228 if phase == DispatchPhase::Bubble {
229 (listener)(action, cx)
230 }
231 }),
232 ));
233 self
234 }
235
236 fn on_boxed_action(
237 mut self,
238 action: &Box<dyn Action>,
239 listener: impl Fn(&Box<dyn Action>, &mut WindowContext) + 'static,
240 ) -> Self {
241 let action = action.boxed_clone();
242 self.interactivity().action_listeners.push((
243 (*action).type_id(),
244 Box::new(move |_, phase, cx| {
245 if phase == DispatchPhase::Bubble {
246 (listener)(&action, cx)
247 }
248 }),
249 ));
250 self
251 }
252
253 fn on_key_down(
254 mut self,
255 listener: impl Fn(&KeyDownEvent, &mut WindowContext) + 'static,
256 ) -> Self {
257 self.interactivity()
258 .key_down_listeners
259 .push(Box::new(move |event, phase, cx| {
260 if phase == DispatchPhase::Bubble {
261 (listener)(event, cx)
262 }
263 }));
264 self
265 }
266
267 fn capture_key_down(
268 mut self,
269 listener: impl Fn(&KeyDownEvent, &mut WindowContext) + 'static,
270 ) -> Self {
271 self.interactivity()
272 .key_down_listeners
273 .push(Box::new(move |event, phase, cx| {
274 if phase == DispatchPhase::Capture {
275 listener(event, cx)
276 }
277 }));
278 self
279 }
280
281 fn on_key_up(mut self, listener: impl Fn(&KeyUpEvent, &mut WindowContext) + 'static) -> Self {
282 self.interactivity()
283 .key_up_listeners
284 .push(Box::new(move |event, phase, cx| {
285 if phase == DispatchPhase::Bubble {
286 listener(event, cx)
287 }
288 }));
289 self
290 }
291
292 fn capture_key_up(
293 mut self,
294 listener: impl Fn(&KeyUpEvent, &mut WindowContext) + 'static,
295 ) -> Self {
296 self.interactivity()
297 .key_up_listeners
298 .push(Box::new(move |event, phase, cx| {
299 if phase == DispatchPhase::Capture {
300 listener(event, cx)
301 }
302 }));
303 self
304 }
305
306 fn drag_over<S: 'static>(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self {
307 self.interactivity()
308 .drag_over_styles
309 .push((TypeId::of::<S>(), f(StyleRefinement::default())));
310 self
311 }
312
313 fn group_drag_over<S: 'static>(
314 mut self,
315 group_name: impl Into<SharedString>,
316 f: impl FnOnce(StyleRefinement) -> StyleRefinement,
317 ) -> Self {
318 self.interactivity().group_drag_over_styles.push((
319 TypeId::of::<S>(),
320 GroupStyle {
321 group: group_name.into(),
322 style: f(StyleRefinement::default()),
323 },
324 ));
325 self
326 }
327
328 fn on_drop<W: 'static>(
329 mut self,
330 listener: impl Fn(&View<W>, &mut WindowContext) + 'static,
331 ) -> Self {
332 self.interactivity().drop_listeners.push((
333 TypeId::of::<W>(),
334 Box::new(move |dragged_view, cx| {
335 listener(&dragged_view.downcast().unwrap(), cx);
336 }),
337 ));
338 self
339 }
340}
341
342pub trait StatefulInteractiveElement: InteractiveElement {
343 fn focusable(mut self) -> Focusable<Self> {
344 self.interactivity().focusable = true;
345 Focusable { element: self }
346 }
347
348 fn overflow_scroll(mut self) -> Self {
349 self.interactivity().base_style.overflow.x = Some(Overflow::Scroll);
350 self.interactivity().base_style.overflow.y = Some(Overflow::Scroll);
351 self
352 }
353
354 fn overflow_x_scroll(mut self) -> Self {
355 self.interactivity().base_style.overflow.x = Some(Overflow::Scroll);
356 self
357 }
358
359 fn overflow_y_scroll(mut self) -> Self {
360 self.interactivity().base_style.overflow.y = Some(Overflow::Scroll);
361 self
362 }
363
364 fn track_scroll(mut self, scroll_handle: &ScrollHandle) -> Self {
365 self.interactivity().scroll_handle = Some(scroll_handle.clone());
366 self
367 }
368
369 fn active(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
370 where
371 Self: Sized,
372 {
373 self.interactivity().active_style = f(StyleRefinement::default());
374 self
375 }
376
377 fn group_active(
378 mut self,
379 group_name: impl Into<SharedString>,
380 f: impl FnOnce(StyleRefinement) -> StyleRefinement,
381 ) -> Self
382 where
383 Self: Sized,
384 {
385 self.interactivity().group_active_style = Some(GroupStyle {
386 group: group_name.into(),
387 style: f(StyleRefinement::default()),
388 });
389 self
390 }
391
392 fn on_click(mut self, listener: impl Fn(&ClickEvent, &mut WindowContext) + 'static) -> Self
393 where
394 Self: Sized,
395 {
396 self.interactivity()
397 .click_listeners
398 .push(Box::new(move |event, cx| listener(event, cx)));
399 self
400 }
401
402 fn on_drag<W>(mut self, listener: impl Fn(&mut WindowContext) -> View<W> + 'static) -> Self
403 where
404 Self: Sized,
405 W: 'static + Render,
406 {
407 debug_assert!(
408 self.interactivity().drag_listener.is_none(),
409 "calling on_drag more than once on the same element is not supported"
410 );
411 self.interactivity().drag_listener = Some(Box::new(move |cursor_offset, cx| AnyDrag {
412 view: listener(cx).into(),
413 cursor_offset,
414 }));
415 self
416 }
417
418 fn on_hover(mut self, listener: impl Fn(&bool, &mut WindowContext) + 'static) -> Self
419 where
420 Self: Sized,
421 {
422 debug_assert!(
423 self.interactivity().hover_listener.is_none(),
424 "calling on_hover more than once on the same element is not supported"
425 );
426 self.interactivity().hover_listener = Some(Box::new(listener));
427 self
428 }
429
430 fn tooltip(mut self, build_tooltip: impl Fn(&mut WindowContext) -> AnyView + 'static) -> Self
431 where
432 Self: Sized,
433 {
434 debug_assert!(
435 self.interactivity().tooltip_builder.is_none(),
436 "calling tooltip more than once on the same element is not supported"
437 );
438 self.interactivity().tooltip_builder = Some(Rc::new(build_tooltip));
439
440 self
441 }
442}
443
444pub trait FocusableElement: InteractiveElement {
445 fn focus(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
446 where
447 Self: Sized,
448 {
449 self.interactivity().focus_style = f(StyleRefinement::default());
450 self
451 }
452
453 fn in_focus(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
454 where
455 Self: Sized,
456 {
457 self.interactivity().in_focus_style = f(StyleRefinement::default());
458 self
459 }
460}
461
462pub type FocusListeners = SmallVec<[FocusListener; 2]>;
463
464pub type FocusListener = Box<dyn Fn(&FocusHandle, &FocusEvent, &mut WindowContext) + 'static>;
465
466pub type MouseDownListener =
467 Box<dyn Fn(&MouseDownEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;
468pub type MouseUpListener =
469 Box<dyn Fn(&MouseUpEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;
470
471pub type MouseMoveListener =
472 Box<dyn Fn(&MouseMoveEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;
473
474pub type ScrollWheelListener =
475 Box<dyn Fn(&ScrollWheelEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;
476
477pub type ClickListener = Box<dyn Fn(&ClickEvent, &mut WindowContext) + 'static>;
478
479pub type DragListener = Box<dyn Fn(Point<Pixels>, &mut WindowContext) -> AnyDrag + 'static>;
480
481type DropListener = dyn Fn(AnyView, &mut WindowContext) + 'static;
482
483pub type TooltipBuilder = Rc<dyn Fn(&mut WindowContext) -> AnyView + 'static>;
484
485pub type KeyDownListener = Box<dyn Fn(&KeyDownEvent, DispatchPhase, &mut WindowContext) + 'static>;
486
487pub type KeyUpListener = Box<dyn Fn(&KeyUpEvent, DispatchPhase, &mut WindowContext) + 'static>;
488
489pub type DragEventListener = Box<dyn Fn(&MouseMoveEvent, &mut WindowContext) + 'static>;
490
491pub type ActionListener = Box<dyn Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static>;
492
493pub fn div() -> Div {
494 Div {
495 interactivity: Interactivity::default(),
496 children: SmallVec::default(),
497 }
498}
499
500pub struct Div {
501 interactivity: Interactivity,
502 children: SmallVec<[AnyElement; 2]>,
503}
504
505impl Styled for Div {
506 fn style(&mut self) -> &mut StyleRefinement {
507 &mut self.interactivity.base_style
508 }
509}
510
511impl InteractiveElement for Div {
512 fn interactivity(&mut self) -> &mut Interactivity {
513 &mut self.interactivity
514 }
515}
516
517impl ParentElement for Div {
518 fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
519 &mut self.children
520 }
521}
522
523impl Element for Div {
524 type State = DivState;
525
526 fn layout(
527 &mut self,
528 element_state: Option<Self::State>,
529 cx: &mut WindowContext,
530 ) -> (LayoutId, Self::State) {
531 let mut child_layout_ids = SmallVec::new();
532 let mut interactivity = mem::take(&mut self.interactivity);
533 let (layout_id, interactive_state) = interactivity.layout(
534 element_state.map(|s| s.interactive_state),
535 cx,
536 |style, cx| {
537 cx.with_text_style(style.text_style().cloned(), |cx| {
538 child_layout_ids = self
539 .children
540 .iter_mut()
541 .map(|child| child.layout(cx))
542 .collect::<SmallVec<_>>();
543 cx.request_layout(&style, child_layout_ids.iter().copied())
544 })
545 },
546 );
547 self.interactivity = interactivity;
548 (
549 layout_id,
550 DivState {
551 interactive_state,
552 child_layout_ids,
553 },
554 )
555 }
556
557 fn paint(
558 self,
559 bounds: Bounds<Pixels>,
560 element_state: &mut Self::State,
561 cx: &mut WindowContext,
562 ) {
563 let mut child_min = point(Pixels::MAX, Pixels::MAX);
564 let mut child_max = Point::default();
565 let content_size = if element_state.child_layout_ids.is_empty() {
566 bounds.size
567 } else if let Some(scroll_handle) = self.interactivity.scroll_handle.as_ref() {
568 let mut state = scroll_handle.0.borrow_mut();
569 state.child_bounds = Vec::with_capacity(element_state.child_layout_ids.len());
570 state.bounds = bounds;
571 let requested = state.requested_scroll_top.take();
572
573 for (ix, child_layout_id) in element_state.child_layout_ids.iter().enumerate() {
574 let child_bounds = cx.layout_bounds(*child_layout_id);
575 child_min = child_min.min(&child_bounds.origin);
576 child_max = child_max.max(&child_bounds.lower_right());
577 state.child_bounds.push(child_bounds);
578
579 if let Some(requested) = requested.as_ref() {
580 if requested.0 == ix {
581 *state.offset.borrow_mut() =
582 bounds.origin - (child_bounds.origin - point(px(0.), requested.1));
583 }
584 }
585 }
586 (child_max - child_min).into()
587 } else {
588 for child_layout_id in &element_state.child_layout_ids {
589 let child_bounds = cx.layout_bounds(*child_layout_id);
590 child_min = child_min.min(&child_bounds.origin);
591 child_max = child_max.max(&child_bounds.lower_right());
592 }
593 (child_max - child_min).into()
594 };
595
596 self.interactivity.paint(
597 bounds,
598 content_size,
599 &mut element_state.interactive_state,
600 cx,
601 |style, scroll_offset, cx| {
602 if style.visibility == Visibility::Hidden {
603 return;
604 }
605
606 let z_index = style.z_index.unwrap_or(0);
607
608 cx.with_z_index(z_index, |cx| {
609 cx.with_z_index(0, |cx| {
610 style.paint(bounds, cx);
611 });
612 cx.with_z_index(1, |cx| {
613 cx.with_text_style(style.text_style().cloned(), |cx| {
614 cx.with_content_mask(style.overflow_mask(bounds), |cx| {
615 cx.with_element_offset(scroll_offset, |cx| {
616 for child in self.children {
617 child.paint(cx);
618 }
619 })
620 })
621 })
622 })
623 })
624 },
625 );
626 }
627}
628
629impl IntoElement for Div {
630 type Element = Self;
631
632 fn element_id(&self) -> Option<ElementId> {
633 self.interactivity.element_id.clone()
634 }
635
636 fn into_element(self) -> Self::Element {
637 self
638 }
639}
640
641pub struct DivState {
642 child_layout_ids: SmallVec<[LayoutId; 4]>,
643 interactive_state: InteractiveElementState,
644}
645
646impl DivState {
647 pub fn is_active(&self) -> bool {
648 self.interactive_state.pending_mouse_down.borrow().is_some()
649 }
650}
651
652pub struct Interactivity {
653 pub element_id: Option<ElementId>,
654 pub key_context: Option<KeyContext>,
655 pub focusable: bool,
656 pub tracked_focus_handle: Option<FocusHandle>,
657 pub scroll_handle: Option<ScrollHandle>,
658 pub focus_listeners: FocusListeners,
659 pub group: Option<SharedString>,
660 pub base_style: StyleRefinement,
661 pub focus_style: StyleRefinement,
662 pub in_focus_style: StyleRefinement,
663 pub hover_style: StyleRefinement,
664 pub group_hover_style: Option<GroupStyle>,
665 pub active_style: StyleRefinement,
666 pub group_active_style: Option<GroupStyle>,
667 pub drag_over_styles: SmallVec<[(TypeId, StyleRefinement); 2]>,
668 pub group_drag_over_styles: SmallVec<[(TypeId, GroupStyle); 2]>,
669 pub mouse_down_listeners: SmallVec<[MouseDownListener; 2]>,
670 pub mouse_up_listeners: SmallVec<[MouseUpListener; 2]>,
671 pub mouse_move_listeners: SmallVec<[MouseMoveListener; 2]>,
672 pub scroll_wheel_listeners: SmallVec<[ScrollWheelListener; 2]>,
673 pub key_down_listeners: SmallVec<[KeyDownListener; 2]>,
674 pub key_up_listeners: SmallVec<[KeyUpListener; 2]>,
675 pub action_listeners: SmallVec<[(TypeId, ActionListener); 8]>,
676 pub drop_listeners: SmallVec<[(TypeId, Box<DropListener>); 2]>,
677 pub click_listeners: SmallVec<[ClickListener; 2]>,
678 pub drag_listener: Option<DragListener>,
679 pub hover_listener: Option<Box<dyn Fn(&bool, &mut WindowContext)>>,
680 pub tooltip_builder: Option<TooltipBuilder>,
681}
682
683#[derive(Clone, Debug)]
684pub struct InteractiveBounds {
685 pub bounds: Bounds<Pixels>,
686 pub stacking_order: StackingOrder,
687}
688
689impl InteractiveBounds {
690 pub fn visibly_contains(&self, point: &Point<Pixels>, cx: &WindowContext) -> bool {
691 self.bounds.contains(point) && cx.was_top_layer(&point, &self.stacking_order)
692 }
693
694 pub fn drag_target_contains(&self, point: &Point<Pixels>, cx: &WindowContext) -> bool {
695 self.bounds.contains(point)
696 && cx.was_top_layer_under_active_drag(&point, &self.stacking_order)
697 }
698}
699
700impl Interactivity {
701 pub fn layout(
702 &mut self,
703 element_state: Option<InteractiveElementState>,
704 cx: &mut WindowContext,
705 f: impl FnOnce(Style, &mut WindowContext) -> LayoutId,
706 ) -> (LayoutId, InteractiveElementState) {
707 let mut element_state = element_state.unwrap_or_default();
708
709 // Ensure we store a focus handle in our element state if we're focusable.
710 // If there's an explicit focus handle we're tracking, use that. Otherwise
711 // create a new handle and store it in the element state, which lives for as
712 // as frames contain an element with this id.
713 if self.focusable {
714 element_state.focus_handle.get_or_insert_with(|| {
715 self.tracked_focus_handle
716 .clone()
717 .unwrap_or_else(|| cx.focus_handle())
718 });
719 }
720
721 if let Some(scroll_handle) = self.scroll_handle.as_ref() {
722 element_state.scroll_offset = Some(scroll_handle.0.borrow().offset.clone());
723 }
724
725 let style = self.compute_style(None, &mut element_state, cx);
726 let layout_id = f(style, cx);
727 (layout_id, element_state)
728 }
729
730 pub fn paint(
731 mut self,
732 bounds: Bounds<Pixels>,
733 content_size: Size<Pixels>,
734 element_state: &mut InteractiveElementState,
735 cx: &mut WindowContext,
736 f: impl FnOnce(Style, Point<Pixels>, &mut WindowContext),
737 ) {
738 let style = self.compute_style(Some(bounds), element_state, cx);
739
740 if style
741 .background
742 .as_ref()
743 .is_some_and(|fill| fill.color().is_some_and(|color| !color.is_transparent()))
744 {
745 cx.with_z_index(style.z_index.unwrap_or(0), |cx| cx.add_opaque_layer(bounds))
746 }
747
748 let interactive_bounds = Rc::new(InteractiveBounds {
749 bounds: bounds.intersect(&cx.content_mask().bounds),
750 stacking_order: cx.stacking_order().clone(),
751 });
752
753 if let Some(mouse_cursor) = style.mouse_cursor {
754 let mouse_position = &cx.mouse_position();
755 let hovered = interactive_bounds.visibly_contains(mouse_position, cx);
756 if hovered {
757 cx.set_cursor_style(mouse_cursor);
758 }
759 }
760
761 for listener in self.mouse_down_listeners.drain(..) {
762 let interactive_bounds = interactive_bounds.clone();
763 cx.on_mouse_event(move |event: &MouseDownEvent, phase, cx| {
764 listener(event, &*interactive_bounds, phase, cx);
765 })
766 }
767
768 for listener in self.mouse_up_listeners.drain(..) {
769 let interactive_bounds = interactive_bounds.clone();
770 cx.on_mouse_event(move |event: &MouseUpEvent, phase, cx| {
771 listener(event, &*interactive_bounds, phase, cx);
772 })
773 }
774
775 for listener in self.mouse_move_listeners.drain(..) {
776 let interactive_bounds = interactive_bounds.clone();
777 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
778 listener(event, &*interactive_bounds, phase, cx);
779 })
780 }
781
782 for listener in self.scroll_wheel_listeners.drain(..) {
783 let interactive_bounds = interactive_bounds.clone();
784 cx.on_mouse_event(move |event: &ScrollWheelEvent, phase, cx| {
785 listener(event, &*interactive_bounds, phase, cx);
786 })
787 }
788
789 let hover_group_bounds = self
790 .group_hover_style
791 .as_ref()
792 .and_then(|group_hover| GroupBounds::get(&group_hover.group, cx));
793
794 if let Some(group_bounds) = hover_group_bounds {
795 let hovered = group_bounds.contains(&cx.mouse_position());
796 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
797 if phase == DispatchPhase::Capture {
798 if group_bounds.contains(&event.position) != hovered {
799 cx.notify();
800 }
801 }
802 });
803 }
804
805 if self.hover_style.is_some()
806 || self.base_style.mouse_cursor.is_some()
807 || cx.active_drag.is_some() && !self.drag_over_styles.is_empty()
808 {
809 let bounds = bounds.intersect(&cx.content_mask().bounds);
810 let hovered = bounds.contains(&cx.mouse_position());
811 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
812 if phase == DispatchPhase::Capture {
813 if bounds.contains(&event.position) != hovered {
814 cx.notify();
815 }
816 }
817 });
818 }
819
820 if cx.active_drag.is_some() {
821 let drop_listeners = mem::take(&mut self.drop_listeners);
822 let interactive_bounds = interactive_bounds.clone();
823 if !drop_listeners.is_empty() {
824 cx.on_mouse_event(move |event: &MouseUpEvent, phase, cx| {
825 if phase == DispatchPhase::Bubble
826 && interactive_bounds.drag_target_contains(&event.position, cx)
827 {
828 if let Some(drag_state_type) =
829 cx.active_drag.as_ref().map(|drag| drag.view.entity_type())
830 {
831 for (drop_state_type, listener) in &drop_listeners {
832 if *drop_state_type == drag_state_type {
833 let drag = cx
834 .active_drag
835 .take()
836 .expect("checked for type drag state type above");
837
838 listener(drag.view.clone(), cx);
839 cx.notify();
840 cx.stop_propagation();
841 }
842 }
843 } else {
844 cx.active_drag = None;
845 }
846 }
847 });
848 }
849 }
850
851 let click_listeners = mem::take(&mut self.click_listeners);
852 let drag_listener = mem::take(&mut self.drag_listener);
853
854 if !click_listeners.is_empty() || drag_listener.is_some() {
855 let pending_mouse_down = element_state.pending_mouse_down.clone();
856 let mouse_down = pending_mouse_down.borrow().clone();
857 if let Some(mouse_down) = mouse_down {
858 if let Some(drag_listener) = drag_listener {
859 let active_state = element_state.clicked_state.clone();
860 let interactive_bounds = interactive_bounds.clone();
861
862 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
863 if cx.active_drag.is_some() {
864 if phase == DispatchPhase::Capture {
865 cx.notify();
866 }
867 } else if phase == DispatchPhase::Bubble
868 && interactive_bounds.visibly_contains(&event.position, cx)
869 && (event.position - mouse_down.position).magnitude() > DRAG_THRESHOLD
870 {
871 *active_state.borrow_mut() = ElementClickedState::default();
872 let cursor_offset = event.position - bounds.origin;
873 let drag = drag_listener(cursor_offset, cx);
874 cx.active_drag = Some(drag);
875 cx.notify();
876 cx.stop_propagation();
877 }
878 });
879 }
880
881 let interactive_bounds = interactive_bounds.clone();
882 cx.on_mouse_event(move |event: &MouseUpEvent, phase, cx| {
883 if phase == DispatchPhase::Bubble
884 && interactive_bounds.visibly_contains(&event.position, cx)
885 {
886 let mouse_click = ClickEvent {
887 down: mouse_down.clone(),
888 up: event.clone(),
889 };
890 for listener in &click_listeners {
891 listener(&mouse_click, cx);
892 }
893 }
894 *pending_mouse_down.borrow_mut() = None;
895 cx.notify();
896 });
897 } else {
898 let interactive_bounds = interactive_bounds.clone();
899 cx.on_mouse_event(move |event: &MouseDownEvent, phase, cx| {
900 if phase == DispatchPhase::Bubble
901 && event.button == MouseButton::Left
902 && interactive_bounds.visibly_contains(&event.position, cx)
903 {
904 *pending_mouse_down.borrow_mut() = Some(event.clone());
905 cx.notify();
906 }
907 });
908 }
909 }
910
911 if let Some(hover_listener) = self.hover_listener.take() {
912 let was_hovered = element_state.hover_state.clone();
913 let has_mouse_down = element_state.pending_mouse_down.clone();
914 let interactive_bounds = interactive_bounds.clone();
915
916 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
917 if phase != DispatchPhase::Bubble {
918 return;
919 }
920 let is_hovered = interactive_bounds.visibly_contains(&event.position, cx)
921 && has_mouse_down.borrow().is_none();
922 let mut was_hovered = was_hovered.borrow_mut();
923
924 if is_hovered != was_hovered.clone() {
925 *was_hovered = is_hovered;
926 drop(was_hovered);
927
928 hover_listener(&is_hovered, cx);
929 }
930 });
931 }
932
933 if let Some(tooltip_builder) = self.tooltip_builder.take() {
934 let active_tooltip = element_state.active_tooltip.clone();
935 let pending_mouse_down = element_state.pending_mouse_down.clone();
936 let interactive_bounds = interactive_bounds.clone();
937
938 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
939 let is_hovered = interactive_bounds.visibly_contains(&event.position, cx)
940 && pending_mouse_down.borrow().is_none();
941 if !is_hovered {
942 active_tooltip.borrow_mut().take();
943 return;
944 }
945
946 if phase != DispatchPhase::Bubble {
947 return;
948 }
949
950 if active_tooltip.borrow().is_none() {
951 let task = cx.spawn({
952 let active_tooltip = active_tooltip.clone();
953 let tooltip_builder = tooltip_builder.clone();
954
955 move |mut cx| async move {
956 cx.background_executor().timer(TOOLTIP_DELAY).await;
957 cx.update(|_, cx| {
958 active_tooltip.borrow_mut().replace(ActiveTooltip {
959 tooltip: Some(AnyTooltip {
960 view: tooltip_builder(cx),
961 cursor_offset: cx.mouse_position(),
962 }),
963 _task: None,
964 });
965 cx.notify();
966 })
967 .ok();
968 }
969 });
970 active_tooltip.borrow_mut().replace(ActiveTooltip {
971 tooltip: None,
972 _task: Some(task),
973 });
974 }
975 });
976
977 let active_tooltip = element_state.active_tooltip.clone();
978 cx.on_mouse_event(move |_: &MouseDownEvent, _, _| {
979 active_tooltip.borrow_mut().take();
980 });
981
982 if let Some(active_tooltip) = element_state.active_tooltip.borrow().as_ref() {
983 if active_tooltip.tooltip.is_some() {
984 cx.active_tooltip = active_tooltip.tooltip.clone()
985 }
986 }
987 }
988
989 let active_state = element_state.clicked_state.clone();
990 if !active_state.borrow().is_clicked() {
991 cx.on_mouse_event(move |_: &MouseUpEvent, phase, cx| {
992 if phase == DispatchPhase::Capture {
993 *active_state.borrow_mut() = ElementClickedState::default();
994 cx.notify();
995 }
996 });
997 } else {
998 let active_group_bounds = self
999 .group_active_style
1000 .as_ref()
1001 .and_then(|group_active| GroupBounds::get(&group_active.group, cx));
1002 let interactive_bounds = interactive_bounds.clone();
1003 cx.on_mouse_event(move |down: &MouseDownEvent, phase, cx| {
1004 if phase == DispatchPhase::Bubble {
1005 let group =
1006 active_group_bounds.map_or(false, |bounds| bounds.contains(&down.position));
1007 let element = interactive_bounds.visibly_contains(&down.position, cx);
1008 if group || element {
1009 *active_state.borrow_mut() = ElementClickedState { group, element };
1010 cx.notify();
1011 }
1012 }
1013 });
1014 }
1015
1016 let overflow = style.overflow;
1017 if overflow.x == Overflow::Scroll || overflow.y == Overflow::Scroll {
1018 let scroll_offset = element_state
1019 .scroll_offset
1020 .get_or_insert_with(Rc::default)
1021 .clone();
1022 let line_height = cx.line_height();
1023 let scroll_max = (content_size - bounds.size).max(&Size::default());
1024 let interactive_bounds = interactive_bounds.clone();
1025
1026 cx.on_mouse_event(move |event: &ScrollWheelEvent, phase, cx| {
1027 if phase == DispatchPhase::Bubble
1028 && interactive_bounds.visibly_contains(&event.position, cx)
1029 {
1030 let mut scroll_offset = scroll_offset.borrow_mut();
1031 let old_scroll_offset = *scroll_offset;
1032 let delta = event.delta.pixel_delta(line_height);
1033
1034 if overflow.x == Overflow::Scroll {
1035 scroll_offset.x =
1036 (scroll_offset.x + delta.x).clamp(-scroll_max.width, px(0.));
1037 }
1038
1039 if overflow.y == Overflow::Scroll {
1040 scroll_offset.y =
1041 (scroll_offset.y + delta.y).clamp(-scroll_max.height, px(0.));
1042 }
1043
1044 if *scroll_offset != old_scroll_offset {
1045 cx.notify();
1046 cx.stop_propagation();
1047 }
1048 }
1049 });
1050 }
1051
1052 if let Some(group) = self.group.clone() {
1053 GroupBounds::push(group, bounds, cx);
1054 }
1055
1056 let scroll_offset = element_state
1057 .scroll_offset
1058 .as_ref()
1059 .map(|scroll_offset| *scroll_offset.borrow());
1060
1061 cx.with_key_dispatch(
1062 self.key_context.clone(),
1063 element_state.focus_handle.clone(),
1064 |_, cx| {
1065 for listener in self.key_down_listeners.drain(..) {
1066 cx.on_key_event(move |event: &KeyDownEvent, phase, cx| {
1067 listener(event, phase, cx);
1068 })
1069 }
1070
1071 for listener in self.key_up_listeners.drain(..) {
1072 cx.on_key_event(move |event: &KeyUpEvent, phase, cx| {
1073 listener(event, phase, cx);
1074 })
1075 }
1076
1077 for (action_type, listener) in self.action_listeners {
1078 cx.on_action(action_type, listener)
1079 }
1080
1081 if let Some(focus_handle) = element_state.focus_handle.as_ref() {
1082 for listener in self.focus_listeners {
1083 let focus_handle = focus_handle.clone();
1084 cx.on_focus_changed(move |event, cx| listener(&focus_handle, event, cx));
1085 }
1086 }
1087
1088 f(style, scroll_offset.unwrap_or_default(), cx)
1089 },
1090 );
1091
1092 if let Some(group) = self.group.as_ref() {
1093 GroupBounds::pop(group, cx);
1094 }
1095 }
1096
1097 pub fn compute_style(
1098 &self,
1099 bounds: Option<Bounds<Pixels>>,
1100 element_state: &mut InteractiveElementState,
1101 cx: &mut WindowContext,
1102 ) -> Style {
1103 let mut style = Style::default();
1104 style.refine(&self.base_style);
1105
1106 if let Some(focus_handle) = self.tracked_focus_handle.as_ref() {
1107 if focus_handle.within_focused(cx) {
1108 style.refine(&self.in_focus_style);
1109 }
1110
1111 if focus_handle.is_focused(cx) {
1112 style.refine(&self.focus_style);
1113 }
1114 }
1115
1116 if let Some(bounds) = bounds {
1117 let mouse_position = cx.mouse_position();
1118 if let Some(group_hover) = self.group_hover_style.as_ref() {
1119 if let Some(group_bounds) = GroupBounds::get(&group_hover.group, cx) {
1120 if group_bounds.contains(&mouse_position)
1121 && cx.was_top_layer(&mouse_position, cx.stacking_order())
1122 {
1123 style.refine(&group_hover.style);
1124 }
1125 }
1126 }
1127 if self.hover_style.is_some() {
1128 if bounds
1129 .intersect(&cx.content_mask().bounds)
1130 .contains(&mouse_position)
1131 && cx.was_top_layer(&mouse_position, cx.stacking_order())
1132 {
1133 style.refine(&self.hover_style);
1134 }
1135 }
1136
1137 if let Some(drag) = cx.active_drag.take() {
1138 for (state_type, group_drag_style) in &self.group_drag_over_styles {
1139 if let Some(group_bounds) = GroupBounds::get(&group_drag_style.group, cx) {
1140 if *state_type == drag.view.entity_type()
1141 && group_bounds.contains(&mouse_position)
1142 {
1143 style.refine(&group_drag_style.style);
1144 }
1145 }
1146 }
1147
1148 for (state_type, drag_over_style) in &self.drag_over_styles {
1149 if *state_type == drag.view.entity_type()
1150 && bounds
1151 .intersect(&cx.content_mask().bounds)
1152 .contains(&mouse_position)
1153 {
1154 style.refine(drag_over_style);
1155 }
1156 }
1157
1158 cx.active_drag = Some(drag);
1159 }
1160 }
1161
1162 let clicked_state = element_state.clicked_state.borrow();
1163 if clicked_state.group {
1164 if let Some(group) = self.group_active_style.as_ref() {
1165 style.refine(&group.style)
1166 }
1167 }
1168
1169 if clicked_state.element {
1170 style.refine(&self.active_style)
1171 }
1172
1173 style
1174 }
1175}
1176
1177impl Default for Interactivity {
1178 fn default() -> Self {
1179 Self {
1180 element_id: None,
1181 key_context: None,
1182 focusable: false,
1183 tracked_focus_handle: None,
1184 scroll_handle: None,
1185 focus_listeners: SmallVec::default(),
1186 // scroll_offset: Point::default(),
1187 group: None,
1188 base_style: StyleRefinement::default(),
1189 focus_style: StyleRefinement::default(),
1190 in_focus_style: StyleRefinement::default(),
1191 hover_style: StyleRefinement::default(),
1192 group_hover_style: None,
1193 active_style: StyleRefinement::default(),
1194 group_active_style: None,
1195 drag_over_styles: SmallVec::new(),
1196 group_drag_over_styles: SmallVec::new(),
1197 mouse_down_listeners: SmallVec::new(),
1198 mouse_up_listeners: SmallVec::new(),
1199 mouse_move_listeners: SmallVec::new(),
1200 scroll_wheel_listeners: SmallVec::new(),
1201 key_down_listeners: SmallVec::new(),
1202 key_up_listeners: SmallVec::new(),
1203 action_listeners: SmallVec::new(),
1204 drop_listeners: SmallVec::new(),
1205 click_listeners: SmallVec::new(),
1206 drag_listener: None,
1207 hover_listener: None,
1208 tooltip_builder: None,
1209 }
1210 }
1211}
1212
1213#[derive(Default)]
1214pub struct InteractiveElementState {
1215 pub focus_handle: Option<FocusHandle>,
1216 pub clicked_state: Rc<RefCell<ElementClickedState>>,
1217 pub hover_state: Rc<RefCell<bool>>,
1218 pub pending_mouse_down: Rc<RefCell<Option<MouseDownEvent>>>,
1219 pub scroll_offset: Option<Rc<RefCell<Point<Pixels>>>>,
1220 pub active_tooltip: Rc<RefCell<Option<ActiveTooltip>>>,
1221}
1222
1223pub struct ActiveTooltip {
1224 tooltip: Option<AnyTooltip>,
1225 _task: Option<Task<()>>,
1226}
1227
1228/// Whether or not the element or a group that contains it is clicked by the mouse.
1229#[derive(Copy, Clone, Default, Eq, PartialEq)]
1230pub struct ElementClickedState {
1231 pub group: bool,
1232 pub element: bool,
1233}
1234
1235impl ElementClickedState {
1236 fn is_clicked(&self) -> bool {
1237 self.group || self.element
1238 }
1239}
1240
1241#[derive(Default)]
1242pub struct GroupBounds(HashMap<SharedString, SmallVec<[Bounds<Pixels>; 1]>>);
1243
1244impl GroupBounds {
1245 pub fn get(name: &SharedString, cx: &mut AppContext) -> Option<Bounds<Pixels>> {
1246 cx.default_global::<Self>()
1247 .0
1248 .get(name)
1249 .and_then(|bounds_stack| bounds_stack.last())
1250 .cloned()
1251 }
1252
1253 pub fn push(name: SharedString, bounds: Bounds<Pixels>, cx: &mut AppContext) {
1254 cx.default_global::<Self>()
1255 .0
1256 .entry(name)
1257 .or_default()
1258 .push(bounds);
1259 }
1260
1261 pub fn pop(name: &SharedString, cx: &mut AppContext) {
1262 cx.default_global::<Self>().0.get_mut(name).unwrap().pop();
1263 }
1264}
1265
1266pub struct Focusable<E> {
1267 pub element: E,
1268}
1269
1270impl<E: InteractiveElement> FocusableElement for Focusable<E> {}
1271
1272impl<E> InteractiveElement for Focusable<E>
1273where
1274 E: InteractiveElement,
1275{
1276 fn interactivity(&mut self) -> &mut Interactivity {
1277 self.element.interactivity()
1278 }
1279}
1280
1281impl<E: StatefulInteractiveElement> StatefulInteractiveElement for Focusable<E> {}
1282
1283impl<E> Styled for Focusable<E>
1284where
1285 E: Styled,
1286{
1287 fn style(&mut self) -> &mut StyleRefinement {
1288 self.element.style()
1289 }
1290}
1291
1292impl<E> Element for Focusable<E>
1293where
1294 E: Element,
1295{
1296 type State = E::State;
1297
1298 fn layout(
1299 &mut self,
1300 state: Option<Self::State>,
1301 cx: &mut WindowContext,
1302 ) -> (LayoutId, Self::State) {
1303 self.element.layout(state, cx)
1304 }
1305
1306 fn paint(self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext) {
1307 self.element.paint(bounds, state, cx)
1308 }
1309}
1310
1311impl<E> IntoElement for Focusable<E>
1312where
1313 E: Element,
1314{
1315 type Element = E;
1316
1317 fn element_id(&self) -> Option<ElementId> {
1318 self.element.element_id()
1319 }
1320
1321 fn into_element(self) -> Self::Element {
1322 self.element
1323 }
1324}
1325
1326impl<E> ParentElement for Focusable<E>
1327where
1328 E: ParentElement,
1329{
1330 fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
1331 self.element.children_mut()
1332 }
1333}
1334
1335pub struct Stateful<E> {
1336 element: E,
1337}
1338
1339impl<E> Styled for Stateful<E>
1340where
1341 E: Styled,
1342{
1343 fn style(&mut self) -> &mut StyleRefinement {
1344 self.element.style()
1345 }
1346}
1347
1348impl<E> StatefulInteractiveElement for Stateful<E>
1349where
1350 E: Element,
1351 Self: InteractiveElement,
1352{
1353}
1354
1355impl<E> InteractiveElement for Stateful<E>
1356where
1357 E: InteractiveElement,
1358{
1359 fn interactivity(&mut self) -> &mut Interactivity {
1360 self.element.interactivity()
1361 }
1362}
1363
1364impl<E: FocusableElement> FocusableElement for Stateful<E> {}
1365
1366impl<E> Element for Stateful<E>
1367where
1368 E: Element,
1369{
1370 type State = E::State;
1371
1372 fn layout(
1373 &mut self,
1374 state: Option<Self::State>,
1375 cx: &mut WindowContext,
1376 ) -> (LayoutId, Self::State) {
1377 self.element.layout(state, cx)
1378 }
1379
1380 fn paint(self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext) {
1381 self.element.paint(bounds, state, cx)
1382 }
1383}
1384
1385impl<E> IntoElement for Stateful<E>
1386where
1387 E: Element,
1388{
1389 type Element = Self;
1390
1391 fn element_id(&self) -> Option<ElementId> {
1392 self.element.element_id()
1393 }
1394
1395 fn into_element(self) -> Self::Element {
1396 self
1397 }
1398}
1399
1400impl<E> ParentElement for Stateful<E>
1401where
1402 E: ParentElement,
1403{
1404 fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
1405 self.element.children_mut()
1406 }
1407}
1408
1409#[derive(Default)]
1410struct ScrollHandleState {
1411 // not great to have the nested rc's...
1412 offset: Rc<RefCell<Point<Pixels>>>,
1413 bounds: Bounds<Pixels>,
1414 child_bounds: Vec<Bounds<Pixels>>,
1415 requested_scroll_top: Option<(usize, Pixels)>,
1416}
1417
1418#[derive(Clone)]
1419pub struct ScrollHandle(Rc<RefCell<ScrollHandleState>>);
1420
1421impl ScrollHandle {
1422 pub fn new() -> Self {
1423 Self(Rc::default())
1424 }
1425
1426 pub fn offset(&self) -> Point<Pixels> {
1427 self.0.borrow().offset.borrow().clone()
1428 }
1429
1430 pub fn top_item(&self) -> usize {
1431 let state = self.0.borrow();
1432 let top = state.bounds.top() - state.offset.borrow().y;
1433
1434 match state.child_bounds.binary_search_by(|bounds| {
1435 if top < bounds.top() {
1436 Ordering::Greater
1437 } else if top > bounds.bottom() {
1438 Ordering::Less
1439 } else {
1440 Ordering::Equal
1441 }
1442 }) {
1443 Ok(ix) => ix,
1444 Err(ix) => ix.min(state.child_bounds.len().saturating_sub(1)),
1445 }
1446 }
1447
1448 pub fn bounds_for_item(&self, ix: usize) -> Option<Bounds<Pixels>> {
1449 self.0.borrow().child_bounds.get(ix).cloned()
1450 }
1451
1452 /// scroll_to_item scrolls the minimal amount to ensure that the item is
1453 /// fully visible
1454 pub fn scroll_to_item(&self, ix: usize) {
1455 let state = self.0.borrow();
1456
1457 let Some(bounds) = state.child_bounds.get(ix) else {
1458 return;
1459 };
1460
1461 let scroll_offset = state.offset.borrow().y;
1462
1463 if bounds.top() + scroll_offset < state.bounds.top() {
1464 state.offset.borrow_mut().y = state.bounds.top() - bounds.top();
1465 } else if bounds.bottom() + scroll_offset > state.bounds.bottom() {
1466 state.offset.borrow_mut().y = state.bounds.bottom() - bounds.bottom();
1467 }
1468 }
1469
1470 pub fn logical_scroll_top(&self) -> (usize, Pixels) {
1471 let ix = self.top_item();
1472 let state = self.0.borrow();
1473
1474 if let Some(child_bounds) = state.child_bounds.get(ix) {
1475 (
1476 ix,
1477 child_bounds.top() + state.offset.borrow().y - state.bounds.top(),
1478 )
1479 } else {
1480 (ix, px(0.))
1481 }
1482 }
1483
1484 pub fn set_logical_scroll_top(&self, ix: usize, px: Pixels) {
1485 self.0.borrow_mut().requested_scroll_top = Some((ix, px));
1486 }
1487}