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[scrollable_positioned_list] Add thumbVisibility parameter #557

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[scrollable_positioned_list] Add thumbVisibility parameter #557

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100 changes: 57 additions & 43 deletions packages/scrollable_positioned_list/lib/src/scrollable_positioned_list.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,8 @@ import 'dart:async';
import 'dart:math';

import 'package:collection/collection.dart' show IterableExtension;
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/widgets.dart';
import 'package:scrollable_positioned_list/scrollable_positioned_list.dart';

import 'item_positions_notifier.dart';
Expand Down Expand Up @@ -57,6 +57,7 @@ class ScrollablePositionedList extends StatefulWidget {
this.addAutomaticKeepAlives = true,
this.addRepaintBoundaries = true,
this.minCacheExtent,
this.thumbVisibility = false,
}) : assert(itemCount != null),
assert(itemBuilder != null),
itemPositionsNotifier = itemPositionsListener as ItemPositionsNotifier?,
Expand Down Expand Up @@ -87,6 +88,7 @@ class ScrollablePositionedList extends StatefulWidget {
this.addAutomaticKeepAlives = true,
this.addRepaintBoundaries = true,
this.minCacheExtent,
this.thumbVisibility = false,
}) : assert(itemCount != null),
assert(itemBuilder != null),
assert(separatorBuilder != null),
Expand Down Expand Up @@ -186,6 +188,14 @@ class ScrollablePositionedList extends StatefulWidget {
/// cache extent.
final double? minCacheExtent;

/// Whether the scrollbar thumb should always be visible.
///
/// When true, the scrollbar thumb will remain visible even when the list is
/// not actively scrolling. Defaults to false.
///
/// This is passed to the internal [Scrollbar.thumbVisibility] parameter.
final bool thumbVisibility;

@override
State<StatefulWidget> createState() => _ScrollablePositionedListState();
}
Expand Down Expand Up @@ -408,58 +418,31 @@ class _ScrollablePositionedListState extends State<ScrollablePositionedList>
return LayoutBuilder(
builder: (context, constraints) {
final cacheExtent = _cacheExtent(constraints);
return Listener(
onPointerDown: (_) => _stopScroll(canceled: true),
child: Stack(
children: <Widget>[
PostMountCallback(
key: primary.key,
callback: startAnimationCallback,
child: FadeTransition(
opacity: ReverseAnimation(opacity),
child: NotificationListener<ScrollNotification>(
onNotification: (_) => _isTransitioning,
child: PositionedList(
itemBuilder: widget.itemBuilder,
separatorBuilder: widget.separatorBuilder,
itemCount: widget.itemCount,
positionedIndex: primary.target,
controller: primary.scrollController,
itemPositionsNotifier: primary.itemPositionsNotifier,
scrollDirection: widget.scrollDirection,
reverse: widget.reverse,
cacheExtent: cacheExtent,
alignment: primary.alignment,
physics: widget.physics,
shrinkWrap: widget.shrinkWrap,
addSemanticIndexes: widget.addSemanticIndexes,
semanticChildCount: widget.semanticChildCount,
padding: widget.padding,
addAutomaticKeepAlives: widget.addAutomaticKeepAlives,
addRepaintBoundaries: widget.addRepaintBoundaries,
),
),
),
),
if (_isTransitioning)
return Scrollbar(
controller: primary.scrollController,
thumbVisibility: widget.thumbVisibility,
child: Listener(
onPointerDown: (_) => _stopScroll(canceled: true),
child: Stack(
children: <Widget>[
PostMountCallback(
key: secondary.key,
key: primary.key,
callback: startAnimationCallback,
child: FadeTransition(
opacity: opacity,
opacity: ReverseAnimation(opacity),
child: NotificationListener<ScrollNotification>(
onNotification: (_) => false,
onNotification: (_) => _isTransitioning,
child: PositionedList(
itemBuilder: widget.itemBuilder,
separatorBuilder: widget.separatorBuilder,
itemCount: widget.itemCount,
itemPositionsNotifier: secondary.itemPositionsNotifier,
positionedIndex: secondary.target,
controller: secondary.scrollController,
positionedIndex: primary.target,
controller: primary.scrollController,
itemPositionsNotifier: primary.itemPositionsNotifier,
scrollDirection: widget.scrollDirection,
reverse: widget.reverse,
cacheExtent: cacheExtent,
alignment: secondary.alignment,
alignment: primary.alignment,
physics: widget.physics,
shrinkWrap: widget.shrinkWrap,
addSemanticIndexes: widget.addSemanticIndexes,
Expand All @@ -471,7 +454,38 @@ class _ScrollablePositionedListState extends State<ScrollablePositionedList>
),
),
),
],
if (_isTransitioning)
PostMountCallback(
key: secondary.key,
callback: startAnimationCallback,
child: FadeTransition(
opacity: opacity,
child: NotificationListener<ScrollNotification>(
onNotification: (_) => false,
child: PositionedList(
itemBuilder: widget.itemBuilder,
separatorBuilder: widget.separatorBuilder,
itemCount: widget.itemCount,
itemPositionsNotifier: secondary.itemPositionsNotifier,
positionedIndex: secondary.target,
controller: secondary.scrollController,
scrollDirection: widget.scrollDirection,
reverse: widget.reverse,
cacheExtent: cacheExtent,
alignment: secondary.alignment,
physics: widget.physics,
shrinkWrap: widget.shrinkWrap,
addSemanticIndexes: widget.addSemanticIndexes,
semanticChildCount: widget.semanticChildCount,
padding: widget.padding,
addAutomaticKeepAlives: widget.addAutomaticKeepAlives,
addRepaintBoundaries: widget.addRepaintBoundaries,
),
),
),
),
],
),
),
);
},
Expand Down
21 changes: 21 additions & 0 deletions packages/scrollable_positioned_list/test/scrollable_positioned_list_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@ void main() {
bool addAutomaticKeepAlives = true,
double? minCacheExtent,
bool variableHeight = false,
bool thumbVisibility = false,
}) async {
tester.view.devicePixelRatio = 1.0;
tester.view.physicalSize = const Size(screenWidth, screenHeight);
Expand Down Expand Up @@ -64,6 +65,7 @@ void main() {
addAutomaticKeepAlives: addAutomaticKeepAlives,
addRepaintBoundaries: addRepaintBoundaries,
minCacheExtent: minCacheExtent,
thumbVisibility: thumbVisibility,
),
),
);
Expand Down Expand Up @@ -2269,6 +2271,25 @@ void main() {
.itemLeadingEdge,
0);
});

testWidgets('Scrollbar thumb is always visible when thumbVisibility is true',
(WidgetTester tester) async {
final itemScrollController = ItemScrollController();

await setUpWidgetTest(
tester,
key: const Key('thumb_test'),
itemScrollController: itemScrollController,
itemPositionsListener: ItemPositionsListener.create(),
thumbVisibility: true,
);

itemScrollController.jumpTo(index: 50);
await tester.pumpAndSettle();

final scrollbar = tester.widget<Scrollbar>(find.byType(Scrollbar));
expect(scrollbar.thumbVisibility, isTrue);
});
}

bool collectSemanticNodes(SemanticsNode root, List<SemanticsNode> nodes) {
Expand Down