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: Box<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 = Some(Box::new(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: Box::new(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: Box::new(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 = Some(Box::new(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: Box::new(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 = Some(Box::new(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 = Some(Box::new(f(StyleRefinement::default())));
458 self
459 }
460}
461
462pub type FocusListeners = Vec<FocusListener>;
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 (layout_id, interactive_state) = self.interactivity.layout(
533 element_state.map(|s| s.interactive_state),
534 cx,
535 |style, cx| {
536 cx.with_text_style(style.text_style().cloned(), |cx| {
537 child_layout_ids = self
538 .children
539 .iter_mut()
540 .map(|child| child.layout(cx))
541 .collect::<SmallVec<_>>();
542 cx.request_layout(&style, child_layout_ids.iter().copied())
543 })
544 },
545 );
546 (
547 layout_id,
548 DivState {
549 interactive_state,
550 child_layout_ids,
551 },
552 )
553 }
554
555 fn paint(
556 self,
557 bounds: Bounds<Pixels>,
558 element_state: &mut Self::State,
559 cx: &mut WindowContext,
560 ) {
561 let mut child_min = point(Pixels::MAX, Pixels::MAX);
562 let mut child_max = Point::default();
563 let content_size = if element_state.child_layout_ids.is_empty() {
564 bounds.size
565 } else if let Some(scroll_handle) = self.interactivity.scroll_handle.as_ref() {
566 let mut state = scroll_handle.0.borrow_mut();
567 state.child_bounds = Vec::with_capacity(element_state.child_layout_ids.len());
568 state.bounds = bounds;
569 let requested = state.requested_scroll_top.take();
570
571 for (ix, child_layout_id) in element_state.child_layout_ids.iter().enumerate() {
572 let child_bounds = cx.layout_bounds(*child_layout_id);
573 child_min = child_min.min(&child_bounds.origin);
574 child_max = child_max.max(&child_bounds.lower_right());
575 state.child_bounds.push(child_bounds);
576
577 if let Some(requested) = requested.as_ref() {
578 if requested.0 == ix {
579 *state.offset.borrow_mut() =
580 bounds.origin - (child_bounds.origin - point(px(0.), requested.1));
581 }
582 }
583 }
584 (child_max - child_min).into()
585 } else {
586 for child_layout_id in &element_state.child_layout_ids {
587 let child_bounds = cx.layout_bounds(*child_layout_id);
588 child_min = child_min.min(&child_bounds.origin);
589 child_max = child_max.max(&child_bounds.lower_right());
590 }
591 (child_max - child_min).into()
592 };
593
594 self.interactivity.paint(
595 bounds,
596 content_size,
597 &mut element_state.interactive_state,
598 cx,
599 |style, scroll_offset, cx| {
600 if style.visibility == Visibility::Hidden {
601 return;
602 }
603
604 let z_index = style.z_index.unwrap_or(0);
605
606 cx.with_z_index(z_index, |cx| {
607 cx.with_z_index(0, |cx| {
608 style.paint(bounds, cx);
609 });
610 cx.with_z_index(1, |cx| {
611 cx.with_text_style(style.text_style().cloned(), |cx| {
612 cx.with_content_mask(style.overflow_mask(bounds), |cx| {
613 cx.with_element_offset(scroll_offset, |cx| {
614 for child in self.children {
615 child.paint(cx);
616 }
617 })
618 })
619 })
620 })
621 })
622 },
623 );
624 }
625}
626
627impl IntoElement for Div {
628 type Element = Self;
629
630 fn element_id(&self) -> Option<ElementId> {
631 self.interactivity.element_id.clone()
632 }
633
634 fn into_element(self) -> Self::Element {
635 self
636 }
637}
638
639pub struct DivState {
640 child_layout_ids: SmallVec<[LayoutId; 2]>,
641 interactive_state: InteractiveElementState,
642}
643
644impl DivState {
645 pub fn is_active(&self) -> bool {
646 self.interactive_state.pending_mouse_down.borrow().is_some()
647 }
648}
649
650pub struct Interactivity {
651 pub element_id: Option<ElementId>,
652 pub key_context: Option<KeyContext>,
653 pub focusable: bool,
654 pub tracked_focus_handle: Option<FocusHandle>,
655 pub scroll_handle: Option<ScrollHandle>,
656 pub focus_listeners: FocusListeners,
657 pub group: Option<SharedString>,
658 pub base_style: Box<StyleRefinement>,
659 pub focus_style: Option<Box<StyleRefinement>>,
660 pub in_focus_style: Option<Box<StyleRefinement>>,
661 pub hover_style: Option<Box<StyleRefinement>>,
662 pub group_hover_style: Option<GroupStyle>,
663 pub active_style: Option<Box<StyleRefinement>>,
664 pub group_active_style: Option<GroupStyle>,
665 pub drag_over_styles: Vec<(TypeId, StyleRefinement)>,
666 pub group_drag_over_styles: Vec<(TypeId, GroupStyle)>,
667 pub mouse_down_listeners: Vec<MouseDownListener>,
668 pub mouse_up_listeners: Vec<MouseUpListener>,
669 pub mouse_move_listeners: Vec<MouseMoveListener>,
670 pub scroll_wheel_listeners: Vec<ScrollWheelListener>,
671 pub key_down_listeners: Vec<KeyDownListener>,
672 pub key_up_listeners: Vec<KeyUpListener>,
673 pub action_listeners: Vec<(TypeId, ActionListener)>,
674 pub drop_listeners: Vec<(TypeId, Box<DropListener>)>,
675 pub click_listeners: Vec<ClickListener>,
676 pub drag_listener: Option<DragListener>,
677 pub hover_listener: Option<Box<dyn Fn(&bool, &mut WindowContext)>>,
678 pub tooltip_builder: Option<TooltipBuilder>,
679}
680
681#[derive(Clone, Debug)]
682pub struct InteractiveBounds {
683 pub bounds: Bounds<Pixels>,
684 pub stacking_order: StackingOrder,
685}
686
687impl InteractiveBounds {
688 pub fn visibly_contains(&self, point: &Point<Pixels>, cx: &WindowContext) -> bool {
689 self.bounds.contains(point) && cx.was_top_layer(&point, &self.stacking_order)
690 }
691
692 pub fn drag_target_contains(&self, point: &Point<Pixels>, cx: &WindowContext) -> bool {
693 self.bounds.contains(point)
694 && cx.was_top_layer_under_active_drag(&point, &self.stacking_order)
695 }
696}
697
698impl Interactivity {
699 pub fn layout(
700 &mut self,
701 element_state: Option<InteractiveElementState>,
702 cx: &mut WindowContext,
703 f: impl FnOnce(Style, &mut WindowContext) -> LayoutId,
704 ) -> (LayoutId, InteractiveElementState) {
705 let mut element_state = element_state.unwrap_or_default();
706
707 // Ensure we store a focus handle in our element state if we're focusable.
708 // If there's an explicit focus handle we're tracking, use that. Otherwise
709 // create a new handle and store it in the element state, which lives for as
710 // as frames contain an element with this id.
711 if self.focusable {
712 element_state.focus_handle.get_or_insert_with(|| {
713 self.tracked_focus_handle
714 .clone()
715 .unwrap_or_else(|| cx.focus_handle())
716 });
717 }
718
719 if let Some(scroll_handle) = self.scroll_handle.as_ref() {
720 element_state.scroll_offset = Some(scroll_handle.0.borrow().offset.clone());
721 }
722
723 let style = self.compute_style(None, &mut element_state, cx);
724 let layout_id = f(style, cx);
725 (layout_id, element_state)
726 }
727
728 pub fn paint(
729 mut self,
730 bounds: Bounds<Pixels>,
731 content_size: Size<Pixels>,
732 element_state: &mut InteractiveElementState,
733 cx: &mut WindowContext,
734 f: impl FnOnce(Style, Point<Pixels>, &mut WindowContext),
735 ) {
736 let style = self.compute_style(Some(bounds), element_state, cx);
737
738 if style
739 .background
740 .as_ref()
741 .is_some_and(|fill| fill.color().is_some_and(|color| !color.is_transparent()))
742 {
743 cx.with_z_index(style.z_index.unwrap_or(0), |cx| cx.add_opaque_layer(bounds))
744 }
745
746 let interactive_bounds = Rc::new(InteractiveBounds {
747 bounds: bounds.intersect(&cx.content_mask().bounds),
748 stacking_order: cx.stacking_order().clone(),
749 });
750
751 if let Some(mouse_cursor) = style.mouse_cursor {
752 let mouse_position = &cx.mouse_position();
753 let hovered = interactive_bounds.visibly_contains(mouse_position, cx);
754 if hovered {
755 cx.set_cursor_style(mouse_cursor);
756 }
757 }
758
759 for listener in self.mouse_down_listeners.drain(..) {
760 let interactive_bounds = interactive_bounds.clone();
761 cx.on_mouse_event(move |event: &MouseDownEvent, phase, cx| {
762 listener(event, &*interactive_bounds, phase, cx);
763 })
764 }
765
766 for listener in self.mouse_up_listeners.drain(..) {
767 let interactive_bounds = interactive_bounds.clone();
768 cx.on_mouse_event(move |event: &MouseUpEvent, phase, cx| {
769 listener(event, &*interactive_bounds, phase, cx);
770 })
771 }
772
773 for listener in self.mouse_move_listeners.drain(..) {
774 let interactive_bounds = interactive_bounds.clone();
775 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
776 listener(event, &*interactive_bounds, phase, cx);
777 })
778 }
779
780 for listener in self.scroll_wheel_listeners.drain(..) {
781 let interactive_bounds = interactive_bounds.clone();
782 cx.on_mouse_event(move |event: &ScrollWheelEvent, phase, cx| {
783 listener(event, &*interactive_bounds, phase, cx);
784 })
785 }
786
787 let hover_group_bounds = self
788 .group_hover_style
789 .as_ref()
790 .and_then(|group_hover| GroupBounds::get(&group_hover.group, cx));
791
792 if let Some(group_bounds) = hover_group_bounds {
793 let hovered = group_bounds.contains(&cx.mouse_position());
794 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
795 if phase == DispatchPhase::Capture {
796 if group_bounds.contains(&event.position) != hovered {
797 cx.notify();
798 }
799 }
800 });
801 }
802
803 if self.hover_style.is_some()
804 || self.base_style.mouse_cursor.is_some()
805 || cx.active_drag.is_some() && !self.drag_over_styles.is_empty()
806 {
807 let bounds = bounds.intersect(&cx.content_mask().bounds);
808 let hovered = bounds.contains(&cx.mouse_position());
809 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
810 if phase == DispatchPhase::Capture {
811 if bounds.contains(&event.position) != hovered {
812 cx.notify();
813 }
814 }
815 });
816 }
817
818 if cx.active_drag.is_some() {
819 let drop_listeners = mem::take(&mut self.drop_listeners);
820 let interactive_bounds = interactive_bounds.clone();
821 if !drop_listeners.is_empty() {
822 cx.on_mouse_event(move |event: &MouseUpEvent, phase, cx| {
823 if phase == DispatchPhase::Bubble
824 && interactive_bounds.drag_target_contains(&event.position, cx)
825 {
826 if let Some(drag_state_type) =
827 cx.active_drag.as_ref().map(|drag| drag.view.entity_type())
828 {
829 for (drop_state_type, listener) in &drop_listeners {
830 if *drop_state_type == drag_state_type {
831 let drag = cx
832 .active_drag
833 .take()
834 .expect("checked for type drag state type above");
835
836 listener(drag.view.clone(), cx);
837 cx.notify();
838 cx.stop_propagation();
839 }
840 }
841 } else {
842 cx.active_drag = None;
843 }
844 }
845 });
846 }
847 }
848
849 let click_listeners = mem::take(&mut self.click_listeners);
850 let drag_listener = mem::take(&mut self.drag_listener);
851
852 if !click_listeners.is_empty() || drag_listener.is_some() {
853 let pending_mouse_down = element_state.pending_mouse_down.clone();
854 let mouse_down = pending_mouse_down.borrow().clone();
855 if let Some(mouse_down) = mouse_down {
856 if let Some(drag_listener) = drag_listener {
857 let active_state = element_state.clicked_state.clone();
858 let interactive_bounds = interactive_bounds.clone();
859
860 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
861 if cx.active_drag.is_some() {
862 if phase == DispatchPhase::Capture {
863 cx.notify();
864 }
865 } else if phase == DispatchPhase::Bubble
866 && interactive_bounds.visibly_contains(&event.position, cx)
867 && (event.position - mouse_down.position).magnitude() > DRAG_THRESHOLD
868 {
869 *active_state.borrow_mut() = ElementClickedState::default();
870 let cursor_offset = event.position - bounds.origin;
871 let drag = drag_listener(cursor_offset, cx);
872 cx.active_drag = Some(drag);
873 cx.notify();
874 cx.stop_propagation();
875 }
876 });
877 }
878
879 let interactive_bounds = interactive_bounds.clone();
880 cx.on_mouse_event(move |event: &MouseUpEvent, phase, cx| {
881 if phase == DispatchPhase::Bubble
882 && interactive_bounds.visibly_contains(&event.position, cx)
883 {
884 let mouse_click = ClickEvent {
885 down: mouse_down.clone(),
886 up: event.clone(),
887 };
888 for listener in &click_listeners {
889 listener(&mouse_click, cx);
890 }
891 }
892 *pending_mouse_down.borrow_mut() = None;
893 cx.notify();
894 });
895 } else {
896 let interactive_bounds = interactive_bounds.clone();
897 cx.on_mouse_event(move |event: &MouseDownEvent, phase, cx| {
898 if phase == DispatchPhase::Bubble
899 && event.button == MouseButton::Left
900 && interactive_bounds.visibly_contains(&event.position, cx)
901 {
902 *pending_mouse_down.borrow_mut() = Some(event.clone());
903 cx.notify();
904 }
905 });
906 }
907 }
908
909 if let Some(hover_listener) = self.hover_listener.take() {
910 let was_hovered = element_state.hover_state.clone();
911 let has_mouse_down = element_state.pending_mouse_down.clone();
912 let interactive_bounds = interactive_bounds.clone();
913
914 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
915 if phase != DispatchPhase::Bubble {
916 return;
917 }
918 let is_hovered = interactive_bounds.visibly_contains(&event.position, cx)
919 && has_mouse_down.borrow().is_none();
920 let mut was_hovered = was_hovered.borrow_mut();
921
922 if is_hovered != was_hovered.clone() {
923 *was_hovered = is_hovered;
924 drop(was_hovered);
925
926 hover_listener(&is_hovered, cx);
927 }
928 });
929 }
930
931 if let Some(tooltip_builder) = self.tooltip_builder.take() {
932 let active_tooltip = element_state.active_tooltip.clone();
933 let pending_mouse_down = element_state.pending_mouse_down.clone();
934 let interactive_bounds = interactive_bounds.clone();
935
936 cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
937 let is_hovered = interactive_bounds.visibly_contains(&event.position, cx)
938 && pending_mouse_down.borrow().is_none();
939 if !is_hovered {
940 active_tooltip.borrow_mut().take();
941 return;
942 }
943
944 if phase != DispatchPhase::Bubble {
945 return;
946 }
947
948 if active_tooltip.borrow().is_none() {
949 let task = cx.spawn({
950 let active_tooltip = active_tooltip.clone();
951 let tooltip_builder = tooltip_builder.clone();
952
953 move |mut cx| async move {
954 cx.background_executor().timer(TOOLTIP_DELAY).await;
955 cx.update(|_, cx| {
956 active_tooltip.borrow_mut().replace(ActiveTooltip {
957 tooltip: Some(AnyTooltip {
958 view: tooltip_builder(cx),
959 cursor_offset: cx.mouse_position(),
960 }),
961 _task: None,
962 });
963 cx.notify();
964 })
965 .ok();
966 }
967 });
968 active_tooltip.borrow_mut().replace(ActiveTooltip {
969 tooltip: None,
970 _task: Some(task),
971 });
972 }
973 });
974
975 let active_tooltip = element_state.active_tooltip.clone();
976 cx.on_mouse_event(move |_: &MouseDownEvent, _, _| {
977 active_tooltip.borrow_mut().take();
978 });
979
980 if let Some(active_tooltip) = element_state.active_tooltip.borrow().as_ref() {
981 if active_tooltip.tooltip.is_some() {
982 cx.active_tooltip = active_tooltip.tooltip.clone()
983 }
984 }
985 }
986
987 let active_state = element_state.clicked_state.clone();
988 if !active_state.borrow().is_clicked() {
989 cx.on_mouse_event(move |_: &MouseUpEvent, phase, cx| {
990 if phase == DispatchPhase::Capture {
991 *active_state.borrow_mut() = ElementClickedState::default();
992 cx.notify();
993 }
994 });
995 } else {
996 let active_group_bounds = self
997 .group_active_style
998 .as_ref()
999 .and_then(|group_active| GroupBounds::get(&group_active.group, cx));
1000 let interactive_bounds = interactive_bounds.clone();
1001 cx.on_mouse_event(move |down: &MouseDownEvent, phase, cx| {
1002 if phase == DispatchPhase::Bubble {
1003 let group =
1004 active_group_bounds.map_or(false, |bounds| bounds.contains(&down.position));
1005 let element = interactive_bounds.visibly_contains(&down.position, cx);
1006 if group || element {
1007 *active_state.borrow_mut() = ElementClickedState { group, element };
1008 cx.notify();
1009 }
1010 }
1011 });
1012 }
1013
1014 let overflow = style.overflow;
1015 if overflow.x == Overflow::Scroll || overflow.y == Overflow::Scroll {
1016 let scroll_offset = element_state
1017 .scroll_offset
1018 .get_or_insert_with(Rc::default)
1019 .clone();
1020 let line_height = cx.line_height();
1021 let scroll_max = (content_size - bounds.size).max(&Size::default());
1022 let interactive_bounds = interactive_bounds.clone();
1023
1024 cx.on_mouse_event(move |event: &ScrollWheelEvent, phase, cx| {
1025 if phase == DispatchPhase::Bubble
1026 && interactive_bounds.visibly_contains(&event.position, cx)
1027 {
1028 let mut scroll_offset = scroll_offset.borrow_mut();
1029 let old_scroll_offset = *scroll_offset;
1030 let delta = event.delta.pixel_delta(line_height);
1031
1032 if overflow.x == Overflow::Scroll {
1033 scroll_offset.x =
1034 (scroll_offset.x + delta.x).clamp(-scroll_max.width, px(0.));
1035 }
1036
1037 if overflow.y == Overflow::Scroll {
1038 scroll_offset.y =
1039 (scroll_offset.y + delta.y).clamp(-scroll_max.height, px(0.));
1040 }
1041
1042 if *scroll_offset != old_scroll_offset {
1043 cx.notify();
1044 cx.stop_propagation();
1045 }
1046 }
1047 });
1048 }
1049
1050 if let Some(group) = self.group.clone() {
1051 GroupBounds::push(group, bounds, cx);
1052 }
1053
1054 let scroll_offset = element_state
1055 .scroll_offset
1056 .as_ref()
1057 .map(|scroll_offset| *scroll_offset.borrow());
1058
1059 cx.with_key_dispatch(
1060 self.key_context.clone(),
1061 element_state.focus_handle.clone(),
1062 |_, cx| {
1063 for listener in self.key_down_listeners.drain(..) {
1064 cx.on_key_event(move |event: &KeyDownEvent, phase, cx| {
1065 listener(event, phase, cx);
1066 })
1067 }
1068
1069 for listener in self.key_up_listeners.drain(..) {
1070 cx.on_key_event(move |event: &KeyUpEvent, phase, cx| {
1071 listener(event, phase, cx);
1072 })
1073 }
1074
1075 for (action_type, listener) in self.action_listeners {
1076 cx.on_action(action_type, listener)
1077 }
1078
1079 if let Some(focus_handle) = element_state.focus_handle.as_ref() {
1080 for listener in self.focus_listeners {
1081 let focus_handle = focus_handle.clone();
1082 cx.on_focus_changed(move |event, cx| listener(&focus_handle, event, cx));
1083 }
1084 }
1085
1086 f(style, scroll_offset.unwrap_or_default(), cx)
1087 },
1088 );
1089
1090 if let Some(group) = self.group.as_ref() {
1091 GroupBounds::pop(group, cx);
1092 }
1093 }
1094
1095 pub fn compute_style(
1096 &self,
1097 bounds: Option<Bounds<Pixels>>,
1098 element_state: &mut InteractiveElementState,
1099 cx: &mut WindowContext,
1100 ) -> Style {
1101 let mut style = Style::default();
1102 style.refine(&self.base_style);
1103
1104 if let Some(focus_handle) = self.tracked_focus_handle.as_ref() {
1105 if let Some(in_focus_style) = self.in_focus_style.as_ref() {
1106 if focus_handle.within_focused(cx) {
1107 style.refine(in_focus_style);
1108 }
1109 }
1110
1111 if let Some(focus_style) = self.focus_style.as_ref() {
1112 if focus_handle.is_focused(cx) {
1113 style.refine(focus_style);
1114 }
1115 }
1116 }
1117
1118 if let Some(bounds) = bounds {
1119 let mouse_position = cx.mouse_position();
1120 if let Some(group_hover) = self.group_hover_style.as_ref() {
1121 if let Some(group_bounds) = GroupBounds::get(&group_hover.group, cx) {
1122 if group_bounds.contains(&mouse_position)
1123 && cx.was_top_layer(&mouse_position, cx.stacking_order())
1124 {
1125 style.refine(&group_hover.style);
1126 }
1127 }
1128 }
1129 if let Some(hover_style) = self.hover_style.as_ref() {
1130 if bounds
1131 .intersect(&cx.content_mask().bounds)
1132 .contains(&mouse_position)
1133 && cx.was_top_layer(&mouse_position, cx.stacking_order())
1134 {
1135 style.refine(hover_style);
1136 }
1137 }
1138
1139 if let Some(drag) = cx.active_drag.take() {
1140 for (state_type, group_drag_style) in &self.group_drag_over_styles {
1141 if let Some(group_bounds) = GroupBounds::get(&group_drag_style.group, cx) {
1142 if *state_type == drag.view.entity_type()
1143 && group_bounds.contains(&mouse_position)
1144 {
1145 style.refine(&group_drag_style.style);
1146 }
1147 }
1148 }
1149
1150 for (state_type, drag_over_style) in &self.drag_over_styles {
1151 if *state_type == drag.view.entity_type()
1152 && bounds
1153 .intersect(&cx.content_mask().bounds)
1154 .contains(&mouse_position)
1155 {
1156 style.refine(drag_over_style);
1157 }
1158 }
1159
1160 cx.active_drag = Some(drag);
1161 }
1162 }
1163
1164 let clicked_state = element_state.clicked_state.borrow();
1165 if clicked_state.group {
1166 if let Some(group) = self.group_active_style.as_ref() {
1167 style.refine(&group.style)
1168 }
1169 }
1170
1171 if let Some(active_style) = self.active_style.as_ref() {
1172 if clicked_state.element {
1173 style.refine(active_style)
1174 }
1175 }
1176
1177 style
1178 }
1179}
1180
1181impl Default for Interactivity {
1182 fn default() -> Self {
1183 Self {
1184 element_id: None,
1185 key_context: None,
1186 focusable: false,
1187 tracked_focus_handle: None,
1188 scroll_handle: None,
1189 focus_listeners: Vec::default(),
1190 // scroll_offset: Point::default(),
1191 group: None,
1192 base_style: Box::new(StyleRefinement::default()),
1193 focus_style: None,
1194 in_focus_style: None,
1195 hover_style: None,
1196 group_hover_style: None,
1197 active_style: None,
1198 group_active_style: None,
1199 drag_over_styles: Vec::new(),
1200 group_drag_over_styles: Vec::new(),
1201 mouse_down_listeners: Vec::new(),
1202 mouse_up_listeners: Vec::new(),
1203 mouse_move_listeners: Vec::new(),
1204 scroll_wheel_listeners: Vec::new(),
1205 key_down_listeners: Vec::new(),
1206 key_up_listeners: Vec::new(),
1207 action_listeners: Vec::new(),
1208 drop_listeners: Vec::new(),
1209 click_listeners: Vec::new(),
1210 drag_listener: None,
1211 hover_listener: None,
1212 tooltip_builder: None,
1213 }
1214 }
1215}
1216
1217#[derive(Default)]
1218pub struct InteractiveElementState {
1219 pub focus_handle: Option<FocusHandle>,
1220 pub clicked_state: Rc<RefCell<ElementClickedState>>,
1221 pub hover_state: Rc<RefCell<bool>>,
1222 pub pending_mouse_down: Rc<RefCell<Option<MouseDownEvent>>>,
1223 pub scroll_offset: Option<Rc<RefCell<Point<Pixels>>>>,
1224 pub active_tooltip: Rc<RefCell<Option<ActiveTooltip>>>,
1225}
1226
1227pub struct ActiveTooltip {
1228 tooltip: Option<AnyTooltip>,
1229 _task: Option<Task<()>>,
1230}
1231
1232/// Whether or not the element or a group that contains it is clicked by the mouse.
1233#[derive(Copy, Clone, Default, Eq, PartialEq)]
1234pub struct ElementClickedState {
1235 pub group: bool,
1236 pub element: bool,
1237}
1238
1239impl ElementClickedState {
1240 fn is_clicked(&self) -> bool {
1241 self.group || self.element
1242 }
1243}
1244
1245#[derive(Default)]
1246pub struct GroupBounds(HashMap<SharedString, SmallVec<[Bounds<Pixels>; 1]>>);
1247
1248impl GroupBounds {
1249 pub fn get(name: &SharedString, cx: &mut AppContext) -> Option<Bounds<Pixels>> {
1250 cx.default_global::<Self>()
1251 .0
1252 .get(name)
1253 .and_then(|bounds_stack| bounds_stack.last())
1254 .cloned()
1255 }
1256
1257 pub fn push(name: SharedString, bounds: Bounds<Pixels>, cx: &mut AppContext) {
1258 cx.default_global::<Self>()
1259 .0
1260 .entry(name)
1261 .or_default()
1262 .push(bounds);
1263 }
1264
1265 pub fn pop(name: &SharedString, cx: &mut AppContext) {
1266 cx.default_global::<Self>().0.get_mut(name).unwrap().pop();
1267 }
1268}
1269
1270pub struct Focusable<E> {
1271 pub element: E,
1272}
1273
1274impl<E: InteractiveElement> FocusableElement for Focusable<E> {}
1275
1276impl<E> InteractiveElement for Focusable<E>
1277where
1278 E: InteractiveElement,
1279{
1280 fn interactivity(&mut self) -> &mut Interactivity {
1281 self.element.interactivity()
1282 }
1283}
1284
1285impl<E: StatefulInteractiveElement> StatefulInteractiveElement for Focusable<E> {}
1286
1287impl<E> Styled for Focusable<E>
1288where
1289 E: Styled,
1290{
1291 fn style(&mut self) -> &mut StyleRefinement {
1292 self.element.style()
1293 }
1294}
1295
1296impl<E> Element for Focusable<E>
1297where
1298 E: Element,
1299{
1300 type State = E::State;
1301
1302 fn layout(
1303 &mut self,
1304 state: Option<Self::State>,
1305 cx: &mut WindowContext,
1306 ) -> (LayoutId, Self::State) {
1307 self.element.layout(state, cx)
1308 }
1309
1310 fn paint(self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext) {
1311 self.element.paint(bounds, state, cx)
1312 }
1313}
1314
1315impl<E> IntoElement for Focusable<E>
1316where
1317 E: Element,
1318{
1319 type Element = E;
1320
1321 fn element_id(&self) -> Option<ElementId> {
1322 self.element.element_id()
1323 }
1324
1325 fn into_element(self) -> Self::Element {
1326 self.element
1327 }
1328}
1329
1330impl<E> ParentElement for Focusable<E>
1331where
1332 E: ParentElement,
1333{
1334 fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
1335 self.element.children_mut()
1336 }
1337}
1338
1339pub struct Stateful<E> {
1340 element: E,
1341}
1342
1343impl<E> Styled for Stateful<E>
1344where
1345 E: Styled,
1346{
1347 fn style(&mut self) -> &mut StyleRefinement {
1348 self.element.style()
1349 }
1350}
1351
1352impl<E> StatefulInteractiveElement for Stateful<E>
1353where
1354 E: Element,
1355 Self: InteractiveElement,
1356{
1357}
1358
1359impl<E> InteractiveElement for Stateful<E>
1360where
1361 E: InteractiveElement,
1362{
1363 fn interactivity(&mut self) -> &mut Interactivity {
1364 self.element.interactivity()
1365 }
1366}
1367
1368impl<E: FocusableElement> FocusableElement for Stateful<E> {}
1369
1370impl<E> Element for Stateful<E>
1371where
1372 E: Element,
1373{
1374 type State = E::State;
1375
1376 fn layout(
1377 &mut self,
1378 state: Option<Self::State>,
1379 cx: &mut WindowContext,
1380 ) -> (LayoutId, Self::State) {
1381 self.element.layout(state, cx)
1382 }
1383
1384 fn paint(self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext) {
1385 self.element.paint(bounds, state, cx)
1386 }
1387}
1388
1389impl<E> IntoElement for Stateful<E>
1390where
1391 E: Element,
1392{
1393 type Element = Self;
1394
1395 fn element_id(&self) -> Option<ElementId> {
1396 self.element.element_id()
1397 }
1398
1399 fn into_element(self) -> Self::Element {
1400 self
1401 }
1402}
1403
1404impl<E> ParentElement for Stateful<E>
1405where
1406 E: ParentElement,
1407{
1408 fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
1409 self.element.children_mut()
1410 }
1411}
1412
1413#[derive(Default)]
1414struct ScrollHandleState {
1415 // not great to have the nested rc's...
1416 offset: Rc<RefCell<Point<Pixels>>>,
1417 bounds: Bounds<Pixels>,
1418 child_bounds: Vec<Bounds<Pixels>>,
1419 requested_scroll_top: Option<(usize, Pixels)>,
1420}
1421
1422#[derive(Clone)]
1423pub struct ScrollHandle(Rc<RefCell<ScrollHandleState>>);
1424
1425impl ScrollHandle {
1426 pub fn new() -> Self {
1427 Self(Rc::default())
1428 }
1429
1430 pub fn offset(&self) -> Point<Pixels> {
1431 self.0.borrow().offset.borrow().clone()
1432 }
1433
1434 pub fn top_item(&self) -> usize {
1435 let state = self.0.borrow();
1436 let top = state.bounds.top() - state.offset.borrow().y;
1437
1438 match state.child_bounds.binary_search_by(|bounds| {
1439 if top < bounds.top() {
1440 Ordering::Greater
1441 } else if top > bounds.bottom() {
1442 Ordering::Less
1443 } else {
1444 Ordering::Equal
1445 }
1446 }) {
1447 Ok(ix) => ix,
1448 Err(ix) => ix.min(state.child_bounds.len().saturating_sub(1)),
1449 }
1450 }
1451
1452 pub fn bounds_for_item(&self, ix: usize) -> Option<Bounds<Pixels>> {
1453 self.0.borrow().child_bounds.get(ix).cloned()
1454 }
1455
1456 /// scroll_to_item scrolls the minimal amount to ensure that the item is
1457 /// fully visible
1458 pub fn scroll_to_item(&self, ix: usize) {
1459 let state = self.0.borrow();
1460
1461 let Some(bounds) = state.child_bounds.get(ix) else {
1462 return;
1463 };
1464
1465 let scroll_offset = state.offset.borrow().y;
1466
1467 if bounds.top() + scroll_offset < state.bounds.top() {
1468 state.offset.borrow_mut().y = state.bounds.top() - bounds.top();
1469 } else if bounds.bottom() + scroll_offset > state.bounds.bottom() {
1470 state.offset.borrow_mut().y = state.bounds.bottom() - bounds.bottom();
1471 }
1472 }
1473
1474 pub fn logical_scroll_top(&self) -> (usize, Pixels) {
1475 let ix = self.top_item();
1476 let state = self.0.borrow();
1477
1478 if let Some(child_bounds) = state.child_bounds.get(ix) {
1479 (
1480 ix,
1481 child_bounds.top() + state.offset.borrow().y - state.bounds.top(),
1482 )
1483 } else {
1484 (ix, px(0.))
1485 }
1486 }
1487
1488 pub fn set_logical_scroll_top(&self, ix: usize, px: Pixels) {
1489 self.0.borrow_mut().requested_scroll_top = Some((ix, px));
1490 }
1491}