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fixed scrolling after scaling

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This commit is contained in:
Thibault Deckers 2020-05-04 12:43:32 +09:00
parent 6e53ce8cf3
commit 2740bdc597
1 changed files with 26 additions and 18 deletions
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44
lib/widgets/album/grid/scaling.dart
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@ -32,6 +32,7 @@ class GridScaleGestureDetector extends StatefulWidget {
class _GridScaleGestureDetectorState extends State<GridScaleGestureDetector> {
double _startExtent, _extentMin, _extentMax;
bool _applyingScale = false;
ValueNotifier<double> _scaledExtentNotifier;
OverlayEntry _overlayEntry;
ThumbnailMetadata _metadata;
@ -47,6 +48,10 @@ class _GridScaleGestureDetectorState extends State<GridScaleGestureDetector> {
// horizontal drag gestures are interpreted as scaling
},
onScaleStart: (details) {
// the gesture detector wrongly detects a new scaling gesture
// when scaling ends and we apply the new extent, so we prevent this
// until we scaled and scrolled to the tile in the new grid
if (_applyingScale) return;
final scrollableContext = widget.scrollableKey.currentContext;
final RenderBox scrollableBox = scrollableContext.findRenderObject();
final result = BoxHitTestResult();
@ -86,12 +91,13 @@ class _GridScaleGestureDetectorState extends State<GridScaleGestureDetector> {
_scaledExtentNotifier.value = (_startExtent * s).clamp(_extentMin, _extentMax);
},
onScaleEnd: (details) {
if (_scaledExtentNotifier == null) return;
if (_overlayEntry != null) {
_overlayEntry.remove();
_overlayEntry = null;
}
if (_scaledExtentNotifier == null) return;
_applyingScale = true;
final oldExtent = tileExtentNotifier.value;
// sanitize and update grid layout if necessary
final newExtent = TileExtentManager.applyTileExtent(
@ -101,23 +107,25 @@ class _GridScaleGestureDetectorState extends State<GridScaleGestureDetector> {
newExtent: _scaledExtentNotifier.value,
);
_scaledExtentNotifier = null;
if (newExtent == oldExtent) return;
// TODO TLAD fix scroll to specific thumbnail with custom SliverList
// scroll to show the focal point thumbnail at its new position
final viewportClosure = _renderViewport;
WidgetsBinding.instance.addPostFrameCallback((_) {
final scrollableContext = widget.scrollableKey.currentContext;
final gridSize = (scrollableContext.findRenderObject() as RenderBox).size;
final sectionLayout = Provider.of<SectionedListLayout>(context, listen: false);
final tileRect = sectionLayout.getTileRect(_metadata.entry);
final scrollOffset = (tileRect?.top ?? 0) - gridSize.height / 2;
viewportClosure.offset.jumpTo(scrollOffset.clamp(.0, double.infinity));
// about scrolling & offset retrieval:
// `Scrollable.ensureVisible` only works on already rendered objects
// `RenderViewport.showOnScreen` can find any `RenderSliver`, but not always a `RenderMetadata`
// `RenderViewport.scrollOffsetOf` is a good alternative
});
if (newExtent == oldExtent) {
_applyingScale = false;
} else {
// scroll to show the focal point thumbnail at its new position
final viewportClosure = _renderViewport;
WidgetsBinding.instance.addPostFrameCallback((_) {
// about scrolling & offset retrieval:
// `Scrollable.ensureVisible` only works on already rendered objects
// `RenderViewport.showOnScreen` can find any `RenderSliver`, but not always a `RenderMetadata`
// `RenderViewport.scrollOffsetOf` is a good alternative
final scrollableContext = widget.scrollableKey.currentContext;
final gridSize = (scrollableContext.findRenderObject() as RenderBox).size;
final sectionLayout = Provider.of<SectionedListLayout>(context, listen: false);
final tileRect = sectionLayout.getTileRect(_metadata.entry);
final scrollOffset = (tileRect?.top ?? 0) - gridSize.height / 2;
viewportClosure.offset.jumpTo(max(.0, scrollOffset));
_applyingScale = false;
});
}
},
child: widget.child,
);