firka/flutter
firka/flutter
4
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix shadows in NestedScrollView (#14279)

Browse Source 
* Fix shadows in NestedScrollView

The previous logic (and especially the previous test) wasn't quite right.

* Update nested_scroll_view.dart
This commit is contained in:
Ian Hickson 2018-01-26 22:36:00 -08:00 committed by GitHub
parent ae1f65ebd6
commit 7701127bdd
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 73 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
packages/flutter/lib/src/widgets/nested_scroll_view.dart
View File

@ -313,10 +313,21 @@ class _NestedScrollViewState extends State<NestedScrollView> {
super.dispose();
}
bool _lastHasScrolledBody;
void _handleHasScrolledBodyChanged() {
if (!mounted)
return;
setState(() { /* _coordinator.hasScrolledBody changed (we use it in the build method) */ });
final bool newHasScrolledBody = _coordinator.hasScrolledBody;
if (_lastHasScrolledBody != newHasScrolledBody) {
setState(() {
// _coordinator.hasScrolledBody changed (we use it in the build method)
// (We record _lastHasScrolledBody in the build() method, rather than in
// this setState call, because the build() method may be called more
// often than just from here, and we want to only call setState when the
// new value is different than the last built value.)
});
}
}
@override
@ -325,6 +336,7 @@ class _NestedScrollViewState extends State<NestedScrollView> {
state: this,
child: new Builder(
builder: (BuildContext context) {
_lastHasScrolledBody = _coordinator.hasScrolledBody;
return new _NestedScrollViewCustomScrollView(
scrollDirection: widget.scrollDirection,
reverse: widget.reverse,
@ -335,7 +347,7 @@ class _NestedScrollViewState extends State<NestedScrollView> {
slivers: widget._buildSlivers(
context,
_coordinator._innerController,
_coordinator.hasScrolledBody,
_lastHasScrolledBody,
),
handle: _absorberHandle,
);
@ -461,13 +473,9 @@ class _NestedScrollCoordinator implements ScrollActivityDelegate, ScrollHoldCont
return false;
}
bool _lastHasScrolledBody;
void updateShadow() {
final bool newHasScrolledBody = hasScrolledBody;
if (_lastHasScrolledBody != newHasScrolledBody) {
if (_onHasScrolledBodyChanged != null)
_onHasScrolledBodyChanged();
}
if (_onHasScrolledBodyChanged != null)
_onHasScrolledBodyChanged();
}
ScrollDirection get userScrollDirection => _userScrollDirection;
@ -833,22 +841,24 @@ class _NestedScrollController extends ScrollController {
super.attach(position);
coordinator.updateParent();
coordinator.updateCanDrag();
position.addListener(_scheduleUpdateShadow);
_scheduleUpdateShadow();
}
@override
void detach(ScrollPosition position) {
assert(position is _NestedScrollPosition);
position.removeListener(_scheduleUpdateShadow);
super.detach(position);
_scheduleUpdateShadow();
}
void _scheduleUpdateShadow() {
// We do this asynchronously for attach() so that the new position has had
// time to be initialized, and we do it asynchronously for detach() because
// that happens synchronously during a frame, at a time where it's too late
// to call setState. Since the result is usually animated, the lag incurred
// is no big deal.
// time to be initialized, and we do it asynchronously for detach() and from
// the position change notifications because those happen synchronously
// during a frame, at a time where it's too late to call setState. Since the
// result is usually animated, the lag incurred is no big deal.
SchedulerBinding.instance.addPostFrameCallback(
(Duration timeStamp) {
coordinator.updateShadow();

56
packages/flutter/test/widgets/nested_scroll_view_test.dart
View File

@ -344,14 +344,17 @@ void main() {
});
testWidgets('NestedScrollView and internal scrolling', (WidgetTester tester) async {
final List<String> _tabs = <String>['Hello', 'World'];
const List<String> _tabs = const <String>['Hello', 'World'];
int buildCount = 0;
await tester.pumpWidget(
new MaterialApp(home: new Material(child:
// THE FOLLOWING SECTION IS FROM THE NestedScrollView DOCUMENTATION
// (EXCEPT FOR THE CHANGES TO THE buildCount COUNTER)
new DefaultTabController(
length: _tabs.length, // This is the number of tabs.
child: new NestedScrollView(
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
buildCount += 1; // THIS LINE IS NOT IN THE ORIGINAL -- ADDED FOR TEST
// These are the slivers that show up in the "outer" scroll view.
return <Widget>[
new SliverOverlapAbsorber(
@ -449,21 +452,46 @@ void main() {
// END
)),
);
int expectedBuildCount = 0;
expectedBuildCount += 1;
expect(buildCount, expectedBuildCount);
expect(find.text('Item 2'), findsOneWidget);
expect(find.text('Item 18'), findsNothing);
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
// scroll down
final TestGesture gesture0 = await tester.startGesture(tester.getCenter(find.text('Item 2')));
await gesture0.moveBy(const Offset(0.0, -120.0)); // tiny bit more than the pinned app bar height (56px * 2)
await tester.pump();
expect(buildCount, expectedBuildCount);
expect(find.text('Item 2'), findsOneWidget);
expect(find.text('Item 18'), findsNothing);
await gesture0.up();
await tester.pump(const Duration(milliseconds: 1)); // start shadow animation
expectedBuildCount += 1;
expect(buildCount, expectedBuildCount);
await tester.pump(const Duration(milliseconds: 1)); // during shadow animation
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), paints..shadow());
await tester.pump(const Duration(seconds: 1)); // end shadow animation
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), paints..shadow());
// scroll down
final TestGesture gesture1 = await tester.startGesture(tester.getCenter(find.text('Item 2')));
await gesture1.moveBy(const Offset(0.0, -800.0));
await tester.pump(); // start shadow animation
await tester.pump();
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), paints..shadow());
expect(find.text('Item 2'), findsNothing);
expect(find.text('Item 18'), findsOneWidget);
await gesture1.up();
await tester.pump(const Duration(seconds: 1)); // end shadow animation
await tester.pump(const Duration(seconds: 1));
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), paints..shadow());
// swipe left to bring in tap on the right
final TestGesture gesture2 = await tester.startGesture(tester.getCenter(find.byType(NestedScrollView)));
await gesture2.moveBy(const Offset(-400.0, 0.0));
await tester.pump();
expect(buildCount, expectedBuildCount);
expect(find.text('Item 18'), findsOneWidget);
expect(find.text('Item 2'), findsOneWidget);
expect(find.text('Item 0'), findsOneWidget);
@ -472,44 +500,61 @@ void main() {
expect(find.byType(NestedScrollView), paints..shadow());
await gesture2.up();
await tester.pump(); // start sideways scroll
await tester.pump(const Duration(seconds: 1)); // end sideways scroll
await tester.pump(); // start shadow going away
await tester.pump(const Duration(seconds: 1)); // end sideways scroll, triggers shadow going away
expect(buildCount, expectedBuildCount);
await tester.pump(const Duration(seconds: 1)); // start shadow going away
expectedBuildCount += 1;
expect(buildCount, expectedBuildCount);
await tester.pump(const Duration(seconds: 1)); // end shadow going away
expect(buildCount, expectedBuildCount);
expect(find.text('Item 18'), findsNothing);
expect(find.text('Item 2'), findsOneWidget);
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
await tester.pump(const Duration(seconds: 1)); // just checking we don't rebuild...
expect(buildCount, expectedBuildCount);
// peek left to see it's still in the right place
final TestGesture gesture3 = await tester.startGesture(tester.getCenter(find.byType(NestedScrollView)));
await gesture3.moveBy(const Offset(400.0, 0.0));
await tester.pump(); // bring the left page into view
expect(buildCount, expectedBuildCount);
await tester.pump(); // shadow comes back starting here
expectedBuildCount += 1;
expect(buildCount, expectedBuildCount);
expect(find.text('Item 18'), findsOneWidget);
expect(find.text('Item 2'), findsOneWidget);
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
await tester.pump(const Duration(seconds: 1)); // shadow finishes coming back
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), paints..shadow());
await gesture3.moveBy(const Offset(-400.0, 0.0));
await gesture3.up();
await tester.pump(); // left tab view goes away
expect(buildCount, expectedBuildCount);
await tester.pump(); // shadow goes away starting here
expectedBuildCount += 1;
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), paints..shadow());
await tester.pump(const Duration(seconds: 1)); // shadow finishes going away
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
// scroll back up
final TestGesture gesture4 = await tester.startGesture(tester.getCenter(find.byType(NestedScrollView)));
await gesture4.moveBy(const Offset(0.0, 200.0)); // expands the appbar again
await tester.pump();
expect(buildCount, expectedBuildCount);
expect(find.text('Item 2'), findsOneWidget);
expect(find.text('Item 18'), findsNothing);
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
await gesture4.up();
await tester.pump(const Duration(seconds: 1));
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
// peek left to see it's now back at zero
final TestGesture gesture5 = await tester.startGesture(tester.getCenter(find.byType(NestedScrollView)));
await gesture5.moveBy(const Offset(400.0, 0.0));
await tester.pump(); // bring the left page into view
await tester.pump(); // shadow would come back starting here, but there's no shadow to show
expect(buildCount, expectedBuildCount);
expect(find.text('Item 18'), findsNothing);
expect(find.text('Item 2'), findsNWidgets(2));
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
@ -518,6 +563,7 @@ void main() {
await gesture5.up();
await tester.pump(); // right tab view goes away
await tester.pumpAndSettle();
expect(buildCount, expectedBuildCount);
expect(find.byType(NestedScrollView), isNot(paints..shadow()));
});
}