highlight thumbnail after scaling

lib/model/collection_lens.dart

@@ -16,6 +16,7 @@ class CollectionLens with ChangeNotifier, CollectionActivityMixin, CollectionSel
   GroupFactor groupFactor;
   SortFactor sortFactor;
   final AChangeNotifier filterChangeNotifier = AChangeNotifier();
+  final StreamController<ImageEntry> _highlightController = StreamController.broadcast();
 
   List<ImageEntry> _filteredEntries;
   List<StreamSubscription> _subscriptions = [];
@@ -74,6 +75,10 @@ class CollectionLens with ChangeNotifier, CollectionActivityMixin, CollectionSel
     return _sortedEntries;
   }
 
+  Stream<ImageEntry> get highlightStream => _highlightController.stream;
+
+  void highlight(ImageEntry entry) => _highlightController.add(entry);
+
   bool get showHeaders {
     if (sortFactor == SortFactor.size) return false;
 

lib/widgets/album/grid/scaling.dart

@@ -17,6 +17,7 @@ class GridScaleGestureDetector extends StatefulWidget {
   final ValueNotifier<double> extentNotifier;
   final Size mqSize;
   final double mqHorizontalPadding;
+  final void Function(ImageEntry entry) onScaled;
   final Widget child;
 
   const GridScaleGestureDetector({
@@ -25,6 +26,7 @@ class GridScaleGestureDetector extends StatefulWidget {
     @required this.extentNotifier,
     @required this.mqSize,
     @required this.mqHorizontalPadding,
+    this.onScaled,
     @required this.child,
   });
 
@@ -112,7 +114,11 @@ class _GridScaleGestureDetectorState extends State<GridScaleGestureDetector> {
         } else {
           // scroll to show the focal point thumbnail at its new position
           WidgetsBinding.instance.addPostFrameCallback((_) {
-            _scrollToEntry(_metadata.entry);
+            final entry = _metadata.entry;
+            _scrollToEntry(entry);
+            WidgetsBinding.instance.addPostFrameCallback((_) {
+              widget.onScaled?.call(entry);
+            });
             _applyingScale = false;
           });
         }

lib/widgets/album/thumbnail/decorated.dart

@@ -1,3 +1,4 @@
+import 'package:aves/model/collection_lens.dart';
 import 'package:aves/model/image_entry.dart';
 import 'package:aves/widgets/album/thumbnail/overlay.dart';
 import 'package:aves/widgets/album/thumbnail/raster.dart';
@@ -7,39 +8,42 @@ import 'package:flutter/material.dart';
 class DecoratedThumbnail extends StatelessWidget {
   final ImageEntry entry;
   final double extent;
-  final Object heroTag;
+  final CollectionLens collection;
   final ValueNotifier<bool> isScrollingNotifier;
   final bool showOverlay;
+  final Object heroTag;
 
   static final Color borderColor = Colors.grey.shade700;
   static const double borderWidth = .5;
 
-  const DecoratedThumbnail({
+  DecoratedThumbnail({
     Key key,
     @required this.entry,
     @required this.extent,
-    this.heroTag,
+    this.collection,
     this.isScrollingNotifier,
     this.showOverlay = true,
-  }) : super(key: key);
+  })  : heroTag = collection?.heroTag(entry),
+        super(key: key);
 
   @override
   Widget build(BuildContext context) {
-    final child = Stack(
-      children: [
-        entry.isSvg
-            ? ThumbnailVectorImage(
-                entry: entry,
-                extent: extent,
-                heroTag: heroTag,
-              )
-            : ThumbnailRasterImage(
-                entry: entry,
-                extent: extent,
-                isScrollingNotifier: isScrollingNotifier,
-                heroTag: heroTag,
-              ),
-        if (showOverlay)
+    var child = entry.isSvg
+        ? ThumbnailVectorImage(
+            entry: entry,
+            extent: extent,
+            heroTag: heroTag,
+          )
+        : ThumbnailRasterImage(
+            entry: entry,
+            extent: extent,
+            isScrollingNotifier: isScrollingNotifier,
+            heroTag: heroTag,
+          );
+    if (showOverlay) {
+      child = Stack(
+        children: [
+          child,
           Positioned(
             bottom: 0,
             left: 0,
@@ -48,13 +52,17 @@ class DecoratedThumbnail extends StatelessWidget {
               extent: extent,
             ),
           ),
-        if (showOverlay)
           ThumbnailSelectionOverlay(
             entry: entry,
             extent: extent,
           ),
-      ],
-    );
+          ThumbnailHighlightOverlay(
+            highlightedStream: collection.highlightStream.map((highlighted) => highlighted == entry),
+            extent: extent,
+          ),
+        ],
+      );
+    }
     return Container(
       decoration: BoxDecoration(
         border: Border.all(

lib/widgets/album/thumbnail/overlay.dart

@@ -2,6 +2,7 @@ import 'dart:math';
 
 import 'package:aves/model/collection_lens.dart';
 import 'package:aves/model/image_entry.dart';
+import 'package:aves/widgets/common/fx/sweeper.dart';
 import 'package:aves/widgets/common/icons.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
@@ -103,3 +104,43 @@ class ThumbnailSelectionOverlay extends StatelessWidget {
     );
   }
 }
+
+class ThumbnailHighlightOverlay extends StatefulWidget {
+  final double extent;
+  final Stream<bool> highlightedStream;
+
+  const ThumbnailHighlightOverlay({
+    Key key,
+    @required this.extent,
+    @required this.highlightedStream,
+  }) : super(key: key);
+
+  @override
+  _ThumbnailHighlightOverlayState createState() => _ThumbnailHighlightOverlayState();
+}
+
+class _ThumbnailHighlightOverlayState extends State<ThumbnailHighlightOverlay> {
+  final ValueNotifier<bool> _highlightedNotifier = ValueNotifier(false);
+
+  @override
+  Widget build(BuildContext context) {
+    return StreamBuilder<bool>(
+      stream: widget.highlightedStream,
+      builder: (context, snapshot) {
+        _highlightedNotifier.value = snapshot.hasData && snapshot.data;
+        return Sweeper(
+          builder: (context) => Container(
+            decoration: BoxDecoration(
+              border: Border.all(
+                color: Theme.of(context).accentColor,
+                width: widget.extent * .1,
+              ),
+            ),
+          ),
+          toggledNotifier: _highlightedNotifier,
+          onSweepEnd: () => _highlightedNotifier.value = false,
+        );
+      },
+    );
+  }
+}

lib/widgets/album/thumbnail_collection.dart

@@ -55,6 +55,7 @@ class ThumbnailCollection extends StatelessWidget {
                 extentNotifier: _tileExtentNotifier,
                 mqSize: mqSize,
                 mqHorizontalPadding: mqHorizontalPadding,
+                onScaled: collection.highlight,
                 child: scrollView,
               );
 
@@ -210,7 +211,6 @@ class _CollectionScrollViewState extends State<CollectionScrollView> {
     widget.isScrollingNotifier.value = true;
     _stopScrollMonitoringTimer();
     _scrollMonitoringTimer = Timer(const Duration(milliseconds: 100), () {
-      debugPrint('$runtimeType _onScrollChange is scrolling false');
       widget.isScrollingNotifier.value = false;
     });
   }

lib/widgets/common/fx/sweeper.dart

@@ -9,6 +9,7 @@ class Sweeper extends StatefulWidget {
   final double sweepAngle;
   final Curve curve;
   final ValueNotifier<bool> toggledNotifier;
+  final VoidCallback onSweepEnd;
 
   const Sweeper({
     Key key,
@@ -17,6 +18,7 @@ class Sweeper extends StatefulWidget {
     this.sweepAngle = pi / 4,
     this.curve = Curves.easeInOutCubic,
     @required this.toggledNotifier,
+    this.onSweepEnd,
   }) : super(key: key);
 
   @override
@@ -96,6 +98,9 @@ class _SweeperState extends State<Sweeper> with SingleTickerProviderStateMixin {
 
   void _onAnimationStatusChange(AnimationStatus status) {
     setState(() {});
+    if (status == AnimationStatus.completed) {
+      widget.onSweepEnd?.call();
+    }
   }
 
   Future<void> _onToggle() async {
@@ -121,10 +126,23 @@ class _SweepClipPath extends CustomClipper<Path> {
 
   @override
   Path getClip(Size size) {
+    final width = size.width;
+    final height = size.height;
+    final centerX = width / 2;
+    final centerY = height / 2;
+    final diagonal = sqrt(width * width + height * height);
     return Path()
-      ..moveTo(size.width / 2, size.height / 2)
-      ..addArc(Rect.fromLTWH(0, 0, size.width, size.height), startAngle, sweepAngle)
-      ..lineTo(size.width / 2, size.height / 2);
+      ..moveTo(centerX, centerY)
+      ..addArc(
+        Rect.fromCenter(
+          center: Offset(centerX, centerY),
+          width: diagonal,
+          height: diagonal,
+        ),
+        startAngle,
+        sweepAngle,
+      )
+      ..lineTo(centerX, centerY);
   }
 
   @override