1use crate::{
2 geometry::{
3 rect::RectF,
4 vector::{vec2f, Vector2F},
5 },
6 json::json,
7 AnyElement, Element, MouseRegion, SceneBuilder, SizeConstraint, View, ViewContext,
8};
9use std::{cell::RefCell, collections::VecDeque, fmt::Debug, ops::Range, rc::Rc};
10use sum_tree::{Bias, SumTree};
11
12pub struct List<V: View> {
13 state: ListState<V>,
14}
15
16pub struct ListState<V: View>(Rc<RefCell<StateInner<V>>>);
17
18#[derive(Clone, Copy, Debug, Eq, PartialEq)]
19pub enum Orientation {
20 Top,
21 Bottom,
22}
23
24struct StateInner<V: View> {
25 last_layout_width: Option<f32>,
26 render_item: Box<dyn FnMut(&mut V, usize, &mut ViewContext<V>) -> AnyElement<V>>,
27 rendered_range: Range<usize>,
28 items: SumTree<ListItem<V>>,
29 logical_scroll_top: Option<ListOffset>,
30 orientation: Orientation,
31 overdraw: f32,
32 #[allow(clippy::type_complexity)]
33 scroll_handler: Option<Box<dyn FnMut(Range<usize>, &mut V, &mut ViewContext<V>)>>,
34}
35
36#[derive(Clone, Copy, Debug, Default, PartialEq)]
37pub struct ListOffset {
38 pub item_ix: usize,
39 pub offset_in_item: f32,
40}
41
42enum ListItem<V: View> {
43 Unrendered,
44 Rendered(Rc<RefCell<AnyElement<V>>>),
45 Removed(f32),
46}
47
48impl<V: View> Clone for ListItem<V> {
49 fn clone(&self) -> Self {
50 match self {
51 Self::Unrendered => Self::Unrendered,
52 Self::Rendered(element) => Self::Rendered(element.clone()),
53 Self::Removed(height) => Self::Removed(*height),
54 }
55 }
56}
57
58impl<V: View> Debug for ListItem<V> {
59 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
60 match self {
61 Self::Unrendered => write!(f, "Unrendered"),
62 Self::Rendered(_) => f.debug_tuple("Rendered").finish(),
63 Self::Removed(height) => f.debug_tuple("Removed").field(height).finish(),
64 }
65 }
66}
67
68#[derive(Clone, Debug, Default, PartialEq)]
69struct ListItemSummary {
70 count: usize,
71 rendered_count: usize,
72 unrendered_count: usize,
73 height: f32,
74}
75
76#[derive(Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
77struct Count(usize);
78
79#[derive(Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
80struct RenderedCount(usize);
81
82#[derive(Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
83struct UnrenderedCount(usize);
84
85#[derive(Clone, Debug, Default)]
86struct Height(f32);
87
88impl<V: View> List<V> {
89 pub fn new(state: ListState<V>) -> Self {
90 Self { state }
91 }
92}
93
94impl<V: View> Element<V> for List<V> {
95 type LayoutState = ListOffset;
96 type PaintState = ();
97
98 fn layout(
99 &mut self,
100 constraint: SizeConstraint,
101 view: &mut V,
102 cx: &mut ViewContext<V>,
103 ) -> (Vector2F, Self::LayoutState) {
104 let state = &mut *self.state.0.borrow_mut();
105 let size = constraint.max;
106 let mut item_constraint = constraint;
107 item_constraint.min.set_y(0.);
108 item_constraint.max.set_y(f32::INFINITY);
109
110 if cx.refreshing || state.last_layout_width != Some(size.x()) {
111 state.rendered_range = 0..0;
112 state.items = SumTree::from_iter(
113 (0..state.items.summary().count).map(|_| ListItem::Unrendered),
114 &(),
115 )
116 }
117
118 let old_items = state.items.clone();
119 let mut new_items = SumTree::new();
120 let mut rendered_items = VecDeque::new();
121 let mut rendered_height = 0.;
122 let mut scroll_top = state.logical_scroll_top();
123
124 // Render items after the scroll top, including those in the trailing overdraw.
125 let mut cursor = old_items.cursor::<Count>();
126 cursor.seek(&Count(scroll_top.item_ix), Bias::Right, &());
127 for (ix, item) in cursor.by_ref().enumerate() {
128 let visible_height = rendered_height - scroll_top.offset_in_item;
129 if visible_height >= size.y() + state.overdraw {
130 break;
131 }
132
133 // Force re-render if the item is visible, but attempt to re-use an existing one
134 // if we are inside the overdraw.
135 let existing_element = if visible_height >= size.y() {
136 Some(item)
137 } else {
138 None
139 };
140 if let Some(element) = state.render_item(
141 scroll_top.item_ix + ix,
142 existing_element,
143 item_constraint,
144 view,
145 cx,
146 ) {
147 rendered_height += element.borrow().size().y();
148 rendered_items.push_back(ListItem::Rendered(element));
149 }
150 }
151
152 // Prepare to start walking upward from the item at the scroll top.
153 cursor.seek(&Count(scroll_top.item_ix), Bias::Right, &());
154
155 // If the rendered items do not fill the visible region, then adjust
156 // the scroll top upward.
157 if rendered_height - scroll_top.offset_in_item < size.y() {
158 while rendered_height < size.y() {
159 cursor.prev(&());
160 if cursor.item().is_some() {
161 if let Some(element) =
162 state.render_item(cursor.start().0, None, item_constraint, view, cx)
163 {
164 rendered_height += element.borrow().size().y();
165 rendered_items.push_front(ListItem::Rendered(element));
166 }
167 } else {
168 break;
169 }
170 }
171
172 scroll_top = ListOffset {
173 item_ix: cursor.start().0,
174 offset_in_item: rendered_height - size.y(),
175 };
176
177 match state.orientation {
178 Orientation::Top => {
179 scroll_top.offset_in_item = scroll_top.offset_in_item.max(0.);
180 state.logical_scroll_top = Some(scroll_top);
181 }
182 Orientation::Bottom => {
183 scroll_top = ListOffset {
184 item_ix: cursor.start().0,
185 offset_in_item: rendered_height - size.y(),
186 };
187 state.logical_scroll_top = None;
188 }
189 };
190 }
191
192 // Render items in the leading overdraw.
193 let mut leading_overdraw = scroll_top.offset_in_item;
194 while leading_overdraw < state.overdraw {
195 cursor.prev(&());
196 if let Some(item) = cursor.item() {
197 if let Some(element) =
198 state.render_item(cursor.start().0, Some(item), item_constraint, view, cx)
199 {
200 leading_overdraw += element.borrow().size().y();
201 rendered_items.push_front(ListItem::Rendered(element));
202 }
203 } else {
204 break;
205 }
206 }
207
208 let new_rendered_range = cursor.start().0..(cursor.start().0 + rendered_items.len());
209
210 let mut cursor = old_items.cursor::<Count>();
211
212 if state.rendered_range.start < new_rendered_range.start {
213 new_items.push_tree(
214 cursor.slice(&Count(state.rendered_range.start), Bias::Right, &()),
215 &(),
216 );
217 let remove_to = state.rendered_range.end.min(new_rendered_range.start);
218 while cursor.start().0 < remove_to {
219 new_items.push(cursor.item().unwrap().remove(), &());
220 cursor.next(&());
221 }
222 }
223 new_items.push_tree(
224 cursor.slice(&Count(new_rendered_range.start), Bias::Right, &()),
225 &(),
226 );
227
228 new_items.extend(rendered_items, &());
229 cursor.seek(&Count(new_rendered_range.end), Bias::Right, &());
230
231 if new_rendered_range.end < state.rendered_range.start {
232 new_items.push_tree(
233 cursor.slice(&Count(state.rendered_range.start), Bias::Right, &()),
234 &(),
235 );
236 }
237 while cursor.start().0 < state.rendered_range.end {
238 new_items.push(cursor.item().unwrap().remove(), &());
239 cursor.next(&());
240 }
241
242 new_items.push_tree(cursor.suffix(&()), &());
243
244 state.items = new_items;
245 state.rendered_range = new_rendered_range;
246 state.last_layout_width = Some(size.x());
247 (size, scroll_top)
248 }
249
250 fn paint(
251 &mut self,
252 scene: &mut SceneBuilder,
253 bounds: RectF,
254 visible_bounds: RectF,
255 scroll_top: &mut ListOffset,
256 view: &mut V,
257 cx: &mut ViewContext<V>,
258 ) {
259 let visible_bounds = visible_bounds.intersection(bounds).unwrap_or_default();
260 scene.push_layer(Some(visible_bounds));
261 scene.push_mouse_region(
262 MouseRegion::new::<Self>(cx.view_id(), 0, bounds).on_scroll({
263 let state = self.state.clone();
264 let height = bounds.height();
265 let scroll_top = scroll_top.clone();
266 move |e, view, cx| {
267 state.0.borrow_mut().scroll(
268 &scroll_top,
269 height,
270 *e.platform_event.delta.raw(),
271 e.platform_event.delta.precise(),
272 view,
273 cx,
274 )
275 }
276 }),
277 );
278
279 let state = &mut *self.state.0.borrow_mut();
280 for (element, origin) in state.visible_elements(bounds, scroll_top) {
281 element
282 .borrow_mut()
283 .paint(scene, origin, visible_bounds, view, cx);
284 }
285
286 scene.pop_layer();
287 }
288
289 fn rect_for_text_range(
290 &self,
291 range_utf16: Range<usize>,
292 bounds: RectF,
293 _: RectF,
294 scroll_top: &Self::LayoutState,
295 _: &Self::PaintState,
296 view: &V,
297 cx: &ViewContext<V>,
298 ) -> Option<RectF> {
299 let state = self.state.0.borrow();
300 let mut item_origin = bounds.origin() - vec2f(0., scroll_top.offset_in_item);
301 let mut cursor = state.items.cursor::<Count>();
302 cursor.seek(&Count(scroll_top.item_ix), Bias::Right, &());
303 while let Some(item) = cursor.item() {
304 if item_origin.y() > bounds.max_y() {
305 break;
306 }
307
308 if let ListItem::Rendered(element) = item {
309 if let Some(rect) =
310 element
311 .borrow()
312 .rect_for_text_range(range_utf16.clone(), view, cx)
313 {
314 return Some(rect);
315 }
316
317 item_origin.set_y(item_origin.y() + element.borrow().size().y());
318 cursor.next(&());
319 } else {
320 unreachable!();
321 }
322 }
323
324 None
325 }
326
327 fn debug(
328 &self,
329 bounds: RectF,
330 scroll_top: &Self::LayoutState,
331 _: &(),
332 view: &V,
333 cx: &ViewContext<V>,
334 ) -> serde_json::Value {
335 let state = self.state.0.borrow_mut();
336 let visible_elements = state
337 .visible_elements(bounds, scroll_top)
338 .map(|e| e.0.borrow().debug(view, cx))
339 .collect::<Vec<_>>();
340 let visible_range = scroll_top.item_ix..(scroll_top.item_ix + visible_elements.len());
341 json!({
342 "visible_range": visible_range,
343 "visible_elements": visible_elements,
344 "scroll_top": state.logical_scroll_top.map(|top| (top.item_ix, top.offset_in_item)),
345 })
346 }
347}
348
349impl<V: View> ListState<V> {
350 pub fn new<D, F>(
351 element_count: usize,
352 orientation: Orientation,
353 overdraw: f32,
354 mut render_item: F,
355 ) -> Self
356 where
357 D: Element<V>,
358 F: 'static + FnMut(&mut V, usize, &mut ViewContext<V>) -> D,
359 {
360 let mut items = SumTree::new();
361 items.extend((0..element_count).map(|_| ListItem::Unrendered), &());
362 Self(Rc::new(RefCell::new(StateInner {
363 last_layout_width: None,
364 render_item: Box::new(move |view, ix, cx| render_item(view, ix, cx).into_any()),
365 rendered_range: 0..0,
366 items,
367 logical_scroll_top: None,
368 orientation,
369 overdraw,
370 scroll_handler: None,
371 })))
372 }
373
374 pub fn reset(&self, element_count: usize) {
375 let state = &mut *self.0.borrow_mut();
376 state.rendered_range = 0..0;
377 state.logical_scroll_top = None;
378 state.items = SumTree::new();
379 state
380 .items
381 .extend((0..element_count).map(|_| ListItem::Unrendered), &());
382 }
383
384 pub fn splice(&self, old_range: Range<usize>, count: usize) {
385 let state = &mut *self.0.borrow_mut();
386
387 if let Some(ListOffset {
388 item_ix,
389 offset_in_item,
390 }) = state.logical_scroll_top.as_mut()
391 {
392 if old_range.contains(item_ix) {
393 *item_ix = old_range.start;
394 *offset_in_item = 0.;
395 } else if old_range.end <= *item_ix {
396 *item_ix = *item_ix - (old_range.end - old_range.start) + count;
397 }
398 }
399
400 let new_end = old_range.start + count;
401 if old_range.start < state.rendered_range.start {
402 state.rendered_range.start =
403 new_end + state.rendered_range.start.saturating_sub(old_range.end);
404 }
405 if old_range.start < state.rendered_range.end {
406 state.rendered_range.end =
407 new_end + state.rendered_range.end.saturating_sub(old_range.end);
408 }
409
410 let mut old_heights = state.items.cursor::<Count>();
411 let mut new_heights = old_heights.slice(&Count(old_range.start), Bias::Right, &());
412 old_heights.seek_forward(&Count(old_range.end), Bias::Right, &());
413
414 new_heights.extend((0..count).map(|_| ListItem::Unrendered), &());
415 new_heights.push_tree(old_heights.suffix(&()), &());
416 drop(old_heights);
417 state.items = new_heights;
418 }
419
420 pub fn set_scroll_handler(
421 &mut self,
422 handler: impl FnMut(Range<usize>, &mut V, &mut ViewContext<V>) + 'static,
423 ) {
424 self.0.borrow_mut().scroll_handler = Some(Box::new(handler))
425 }
426
427 pub fn logical_scroll_top(&self) -> ListOffset {
428 self.0.borrow().logical_scroll_top()
429 }
430
431 pub fn scroll_to(&self, mut scroll_top: ListOffset) {
432 let state = &mut *self.0.borrow_mut();
433 let item_count = state.items.summary().count;
434 if scroll_top.item_ix >= item_count {
435 scroll_top.item_ix = item_count;
436 scroll_top.offset_in_item = 0.;
437 }
438 state.logical_scroll_top = Some(scroll_top);
439 }
440}
441
442impl<V: View> Clone for ListState<V> {
443 fn clone(&self) -> Self {
444 Self(self.0.clone())
445 }
446}
447
448impl<V: View> StateInner<V> {
449 fn render_item(
450 &mut self,
451 ix: usize,
452 existing_element: Option<&ListItem<V>>,
453 constraint: SizeConstraint,
454 view: &mut V,
455 cx: &mut ViewContext<V>,
456 ) -> Option<Rc<RefCell<AnyElement<V>>>> {
457 if let Some(ListItem::Rendered(element)) = existing_element {
458 Some(element.clone())
459 } else {
460 let mut element = (self.render_item)(view, ix, cx);
461 element.layout(constraint, view, cx);
462 Some(Rc::new(RefCell::new(element)))
463 }
464 }
465
466 fn visible_range(&self, height: f32, scroll_top: &ListOffset) -> Range<usize> {
467 let mut cursor = self.items.cursor::<ListItemSummary>();
468 cursor.seek(&Count(scroll_top.item_ix), Bias::Right, &());
469 let start_y = cursor.start().height + scroll_top.offset_in_item;
470 cursor.seek_forward(&Height(start_y + height), Bias::Left, &());
471 scroll_top.item_ix..cursor.start().count + 1
472 }
473
474 fn visible_elements<'a>(
475 &'a self,
476 bounds: RectF,
477 scroll_top: &ListOffset,
478 ) -> impl Iterator<Item = (Rc<RefCell<AnyElement<V>>>, Vector2F)> + 'a {
479 let mut item_origin = bounds.origin() - vec2f(0., scroll_top.offset_in_item);
480 let mut cursor = self.items.cursor::<Count>();
481 cursor.seek(&Count(scroll_top.item_ix), Bias::Right, &());
482 std::iter::from_fn(move || {
483 while let Some(item) = cursor.item() {
484 if item_origin.y() > bounds.max_y() {
485 break;
486 }
487
488 if let ListItem::Rendered(element) = item {
489 let result = (element.clone(), item_origin);
490 item_origin.set_y(item_origin.y() + element.borrow().size().y());
491 cursor.next(&());
492 return Some(result);
493 }
494
495 cursor.next(&());
496 }
497
498 None
499 })
500 }
501
502 fn scroll(
503 &mut self,
504 scroll_top: &ListOffset,
505 height: f32,
506 mut delta: Vector2F,
507 precise: bool,
508 view: &mut V,
509 cx: &mut ViewContext<V>,
510 ) {
511 if !precise {
512 delta *= 20.;
513 }
514
515 let scroll_max = (self.items.summary().height - height).max(0.);
516 let new_scroll_top = (self.scroll_top(scroll_top) - delta.y())
517 .max(0.)
518 .min(scroll_max);
519
520 if self.orientation == Orientation::Bottom && new_scroll_top == scroll_max {
521 self.logical_scroll_top = None;
522 } else {
523 let mut cursor = self.items.cursor::<ListItemSummary>();
524 cursor.seek(&Height(new_scroll_top), Bias::Right, &());
525 let item_ix = cursor.start().count;
526 let offset_in_item = new_scroll_top - cursor.start().height;
527 self.logical_scroll_top = Some(ListOffset {
528 item_ix,
529 offset_in_item,
530 });
531 }
532
533 if self.scroll_handler.is_some() {
534 let visible_range = self.visible_range(height, scroll_top);
535 self.scroll_handler.as_mut().unwrap()(visible_range, view, cx);
536 }
537
538 cx.notify();
539 }
540
541 fn logical_scroll_top(&self) -> ListOffset {
542 self.logical_scroll_top
543 .unwrap_or_else(|| match self.orientation {
544 Orientation::Top => ListOffset {
545 item_ix: 0,
546 offset_in_item: 0.,
547 },
548 Orientation::Bottom => ListOffset {
549 item_ix: self.items.summary().count,
550 offset_in_item: 0.,
551 },
552 })
553 }
554
555 fn scroll_top(&self, logical_scroll_top: &ListOffset) -> f32 {
556 let mut cursor = self.items.cursor::<ListItemSummary>();
557 cursor.seek(&Count(logical_scroll_top.item_ix), Bias::Right, &());
558 cursor.start().height + logical_scroll_top.offset_in_item
559 }
560}
561
562impl<V: View> ListItem<V> {
563 fn remove(&self) -> Self {
564 match self {
565 ListItem::Unrendered => ListItem::Unrendered,
566 ListItem::Rendered(element) => ListItem::Removed(element.borrow().size().y()),
567 ListItem::Removed(height) => ListItem::Removed(*height),
568 }
569 }
570}
571
572impl<V: View> sum_tree::Item for ListItem<V> {
573 type Summary = ListItemSummary;
574
575 fn summary(&self) -> Self::Summary {
576 match self {
577 ListItem::Unrendered => ListItemSummary {
578 count: 1,
579 rendered_count: 0,
580 unrendered_count: 1,
581 height: 0.,
582 },
583 ListItem::Rendered(element) => ListItemSummary {
584 count: 1,
585 rendered_count: 1,
586 unrendered_count: 0,
587 height: element.borrow().size().y(),
588 },
589 ListItem::Removed(height) => ListItemSummary {
590 count: 1,
591 rendered_count: 0,
592 unrendered_count: 1,
593 height: *height,
594 },
595 }
596 }
597}
598
599impl sum_tree::Summary for ListItemSummary {
600 type Context = ();
601
602 fn add_summary(&mut self, summary: &Self, _: &()) {
603 self.count += summary.count;
604 self.rendered_count += summary.rendered_count;
605 self.unrendered_count += summary.unrendered_count;
606 self.height += summary.height;
607 }
608}
609
610impl<'a> sum_tree::Dimension<'a, ListItemSummary> for Count {
611 fn add_summary(&mut self, summary: &'a ListItemSummary, _: &()) {
612 self.0 += summary.count;
613 }
614}
615
616impl<'a> sum_tree::Dimension<'a, ListItemSummary> for RenderedCount {
617 fn add_summary(&mut self, summary: &'a ListItemSummary, _: &()) {
618 self.0 += summary.rendered_count;
619 }
620}
621
622impl<'a> sum_tree::Dimension<'a, ListItemSummary> for UnrenderedCount {
623 fn add_summary(&mut self, summary: &'a ListItemSummary, _: &()) {
624 self.0 += summary.unrendered_count;
625 }
626}
627
628impl<'a> sum_tree::Dimension<'a, ListItemSummary> for Height {
629 fn add_summary(&mut self, summary: &'a ListItemSummary, _: &()) {
630 self.0 += summary.height;
631 }
632}
633
634impl<'a> sum_tree::SeekTarget<'a, ListItemSummary, ListItemSummary> for Count {
635 fn cmp(&self, other: &ListItemSummary, _: &()) -> std::cmp::Ordering {
636 self.0.partial_cmp(&other.count).unwrap()
637 }
638}
639
640impl<'a> sum_tree::SeekTarget<'a, ListItemSummary, ListItemSummary> for Height {
641 fn cmp(&self, other: &ListItemSummary, _: &()) -> std::cmp::Ordering {
642 self.0.partial_cmp(&other.height).unwrap()
643 }
644}
645
646#[cfg(test)]
647mod tests {
648 use super::*;
649 use crate::{elements::Empty, geometry::vector::vec2f, Entity};
650 use rand::prelude::*;
651 use std::env;
652
653 #[crate::test(self)]
654 fn test_layout(cx: &mut crate::AppContext) {
655 cx.add_window(Default::default(), |cx| {
656 let mut view = TestView;
657 let constraint = SizeConstraint::new(vec2f(0., 0.), vec2f(100., 40.));
658 let elements = Rc::new(RefCell::new(vec![(0, 20.), (1, 30.), (2, 100.)]));
659 let state = ListState::new(elements.borrow().len(), Orientation::Top, 1000.0, {
660 let elements = elements.clone();
661 move |_, ix, _| {
662 let (id, height) = elements.borrow()[ix];
663 TestElement::new(id, height).into_any()
664 }
665 });
666
667 let mut list = List::new(state.clone());
668 let (size, _) = list.layout(constraint, &mut view, cx);
669 assert_eq!(size, vec2f(100., 40.));
670 assert_eq!(
671 state.0.borrow().items.summary().clone(),
672 ListItemSummary {
673 count: 3,
674 rendered_count: 3,
675 unrendered_count: 0,
676 height: 150.
677 }
678 );
679
680 state.0.borrow_mut().scroll(
681 &ListOffset {
682 item_ix: 0,
683 offset_in_item: 0.,
684 },
685 40.,
686 vec2f(0., -54.),
687 true,
688 &mut view,
689 cx,
690 );
691
692 let (_, logical_scroll_top) = list.layout(constraint, &mut view, cx);
693 assert_eq!(
694 logical_scroll_top,
695 ListOffset {
696 item_ix: 2,
697 offset_in_item: 4.
698 }
699 );
700 assert_eq!(state.0.borrow().scroll_top(&logical_scroll_top), 54.);
701
702 elements.borrow_mut().splice(1..2, vec![(3, 40.), (4, 50.)]);
703 elements.borrow_mut().push((5, 60.));
704 state.splice(1..2, 2);
705 state.splice(4..4, 1);
706 assert_eq!(
707 state.0.borrow().items.summary().clone(),
708 ListItemSummary {
709 count: 5,
710 rendered_count: 2,
711 unrendered_count: 3,
712 height: 120.
713 }
714 );
715
716 let (size, logical_scroll_top) = list.layout(constraint, &mut view, cx);
717 assert_eq!(size, vec2f(100., 40.));
718 assert_eq!(
719 state.0.borrow().items.summary().clone(),
720 ListItemSummary {
721 count: 5,
722 rendered_count: 5,
723 unrendered_count: 0,
724 height: 270.
725 }
726 );
727 assert_eq!(
728 logical_scroll_top,
729 ListOffset {
730 item_ix: 3,
731 offset_in_item: 4.
732 }
733 );
734 assert_eq!(state.0.borrow().scroll_top(&logical_scroll_top), 114.);
735
736 view
737 });
738 }
739
740 #[crate::test(self, iterations = 10)]
741 fn test_random(cx: &mut crate::AppContext, mut rng: StdRng) {
742 let operations = env::var("OPERATIONS")
743 .map(|i| i.parse().expect("invalid `OPERATIONS` variable"))
744 .unwrap_or(10);
745
746 cx.add_window(Default::default(), |cx| {
747 let mut view = TestView;
748
749 let mut next_id = 0;
750 let elements = Rc::new(RefCell::new(
751 (0..rng.gen_range(0..=20))
752 .map(|_| {
753 let id = next_id;
754 next_id += 1;
755 (id, rng.gen_range(0..=200) as f32 / 2.0)
756 })
757 .collect::<Vec<_>>(),
758 ));
759 let orientation = *[Orientation::Top, Orientation::Bottom]
760 .choose(&mut rng)
761 .unwrap();
762 let overdraw = rng.gen_range(1..=100) as f32;
763
764 let state = ListState::new(elements.borrow().len(), orientation, overdraw, {
765 let elements = elements.clone();
766 move |_, ix, _| {
767 let (id, height) = elements.borrow()[ix];
768 TestElement::new(id, height).into_any()
769 }
770 });
771
772 let mut width = rng.gen_range(0..=2000) as f32 / 2.;
773 let mut height = rng.gen_range(0..=2000) as f32 / 2.;
774 log::info!("orientation: {:?}", orientation);
775 log::info!("overdraw: {}", overdraw);
776 log::info!("elements: {:?}", elements.borrow());
777 log::info!("size: ({:?}, {:?})", width, height);
778 log::info!("==================");
779
780 let mut last_logical_scroll_top = None;
781 for _ in 0..operations {
782 match rng.gen_range(0..=100) {
783 0..=29 if last_logical_scroll_top.is_some() => {
784 let delta = vec2f(0., rng.gen_range(-overdraw..=overdraw));
785 log::info!(
786 "Scrolling by {:?}, previous scroll top: {:?}",
787 delta,
788 last_logical_scroll_top.unwrap()
789 );
790 state.0.borrow_mut().scroll(
791 last_logical_scroll_top.as_ref().unwrap(),
792 height,
793 delta,
794 true,
795 &mut view,
796 cx,
797 );
798 }
799 30..=34 => {
800 width = rng.gen_range(0..=2000) as f32 / 2.;
801 log::info!("changing width: {:?}", width);
802 }
803 35..=54 => {
804 height = rng.gen_range(0..=1000) as f32 / 2.;
805 log::info!("changing height: {:?}", height);
806 }
807 _ => {
808 let mut elements = elements.borrow_mut();
809 let end_ix = rng.gen_range(0..=elements.len());
810 let start_ix = rng.gen_range(0..=end_ix);
811 let new_elements = (0..rng.gen_range(0..10))
812 .map(|_| {
813 let id = next_id;
814 next_id += 1;
815 (id, rng.gen_range(0..=200) as f32 / 2.)
816 })
817 .collect::<Vec<_>>();
818 log::info!("splice({:?}, {:?})", start_ix..end_ix, new_elements);
819 state.splice(start_ix..end_ix, new_elements.len());
820 elements.splice(start_ix..end_ix, new_elements);
821 for (ix, item) in state.0.borrow().items.cursor::<()>().enumerate() {
822 if let ListItem::Rendered(element) = item {
823 let (expected_id, _) = elements[ix];
824 element.borrow().with_metadata(|metadata: Option<&usize>| {
825 assert_eq!(*metadata.unwrap(), expected_id);
826 });
827 }
828 }
829 }
830 }
831
832 let mut list = List::new(state.clone());
833 let window_size = vec2f(width, height);
834 let (size, logical_scroll_top) = list.layout(
835 SizeConstraint::new(vec2f(0., 0.), window_size),
836 &mut view,
837 cx,
838 );
839 assert_eq!(size, window_size);
840 last_logical_scroll_top = Some(logical_scroll_top);
841
842 let state = state.0.borrow();
843 log::info!("items {:?}", state.items.items(&()));
844
845 let scroll_top = state.scroll_top(&logical_scroll_top);
846 let rendered_top = (scroll_top - overdraw).max(0.);
847 let rendered_bottom = scroll_top + height + overdraw;
848 let mut item_top = 0.;
849
850 log::info!(
851 "rendered top {:?}, rendered bottom {:?}, scroll top {:?}",
852 rendered_top,
853 rendered_bottom,
854 scroll_top,
855 );
856
857 let mut first_rendered_element_top = None;
858 let mut last_rendered_element_bottom = None;
859 assert_eq!(state.items.summary().count, elements.borrow().len());
860 for (ix, item) in state.items.cursor::<()>().enumerate() {
861 match item {
862 ListItem::Unrendered => {
863 let item_bottom = item_top;
864 assert!(item_bottom <= rendered_top || item_top >= rendered_bottom);
865 item_top = item_bottom;
866 }
867 ListItem::Removed(height) => {
868 let (id, expected_height) = elements.borrow()[ix];
869 assert_eq!(
870 *height, expected_height,
871 "element {} height didn't match",
872 id
873 );
874 let item_bottom = item_top + height;
875 assert!(item_bottom <= rendered_top || item_top >= rendered_bottom);
876 item_top = item_bottom;
877 }
878 ListItem::Rendered(element) => {
879 let (expected_id, expected_height) = elements.borrow()[ix];
880 let element = element.borrow();
881 element.with_metadata(|metadata: Option<&usize>| {
882 assert_eq!(*metadata.unwrap(), expected_id);
883 });
884 assert_eq!(element.size().y(), expected_height);
885 let item_bottom = item_top + element.size().y();
886 first_rendered_element_top.get_or_insert(item_top);
887 last_rendered_element_bottom = Some(item_bottom);
888 assert!(item_bottom > rendered_top || item_top < rendered_bottom);
889 item_top = item_bottom;
890 }
891 }
892 }
893
894 match orientation {
895 Orientation::Top => {
896 if let Some(first_rendered_element_top) = first_rendered_element_top {
897 assert!(first_rendered_element_top <= scroll_top);
898 }
899 }
900 Orientation::Bottom => {
901 if let Some(last_rendered_element_bottom) = last_rendered_element_bottom {
902 assert!(last_rendered_element_bottom >= scroll_top + height);
903 }
904 }
905 }
906 }
907
908 view
909 });
910 }
911
912 struct TestView;
913
914 impl Entity for TestView {
915 type Event = ();
916 }
917
918 impl View for TestView {
919 fn ui_name() -> &'static str {
920 "TestView"
921 }
922
923 fn render(&mut self, _: &mut ViewContext<Self>) -> AnyElement<Self> {
924 Empty::new().into_any()
925 }
926 }
927
928 struct TestElement {
929 id: usize,
930 size: Vector2F,
931 }
932
933 impl TestElement {
934 fn new(id: usize, height: f32) -> Self {
935 Self {
936 id,
937 size: vec2f(100., height),
938 }
939 }
940 }
941
942 impl<V: View> Element<V> for TestElement {
943 type LayoutState = ();
944 type PaintState = ();
945
946 fn layout(
947 &mut self,
948 _: SizeConstraint,
949 _: &mut V,
950 _: &mut ViewContext<V>,
951 ) -> (Vector2F, ()) {
952 (self.size, ())
953 }
954
955 fn paint(
956 &mut self,
957 _: &mut SceneBuilder,
958 _: RectF,
959 _: RectF,
960 _: &mut (),
961 _: &mut V,
962 _: &mut ViewContext<V>,
963 ) {
964 todo!()
965 }
966
967 fn rect_for_text_range(
968 &self,
969 _: Range<usize>,
970 _: RectF,
971 _: RectF,
972 _: &Self::LayoutState,
973 _: &Self::PaintState,
974 _: &V,
975 _: &ViewContext<V>,
976 ) -> Option<RectF> {
977 todo!()
978 }
979
980 fn debug(&self, _: RectF, _: &(), _: &(), _: &V, _: &ViewContext<V>) -> serde_json::Value {
981 self.id.into()
982 }
983
984 fn metadata(&self) -> Option<&dyn std::any::Any> {
985 Some(&self.id)
986 }
987 }
988}