multipage: thumbnail request cancellation

lib/model/entry.dart

@@ -172,6 +172,15 @@ class AvesEntry {
     addressChangeNotifier.dispose();
   }
 
+  @override
+  bool operator ==(Object other) {
+    if (other.runtimeType != runtimeType) return false;
+    return other is AvesEntry && other.uri == uri && other.pageId == pageId && other._dateModifiedSecs == _dateModifiedSecs;
+  }
+
+  @override
+  int get hashCode => hashValues(uri, pageId, _dateModifiedSecs);
+
   @override
   String toString() => '$runtimeType#${shortHash(this)}{uri=$uri, path=$path, pageId=$pageId}';
 

lib/model/multipage.dart

@@ -1,11 +1,13 @@
 import 'package:flutter/foundation.dart';
 
 class MultiPageInfo {
+  final String uri;
   final List<SinglePageInfo> pages;
 
   int get pageCount => pages.length;
 
   MultiPageInfo({
+    @required this.uri,
     this.pages,
   }) {
     if (pages.isNotEmpty) {
@@ -18,8 +20,11 @@ class MultiPageInfo {
     }
   }
 
-  factory MultiPageInfo.fromPageMaps(List<Map> pageMaps) {
+  factory MultiPageInfo.fromPageMaps(String uri, List<Map> pageMaps) {
-    return MultiPageInfo(pages: pageMaps.map((page) => SinglePageInfo.fromMap(page)).toList());
+    return MultiPageInfo(
+      uri: uri,
+      pages: pageMaps.map((page) => SinglePageInfo.fromMap(page)).toList(),
+    );
   }
 
   SinglePageInfo get defaultPage => pages.firstWhere((page) => page.isDefault, orElse: () => null);
@@ -29,7 +34,7 @@ class MultiPageInfo {
   SinglePageInfo getById(int pageId) => pages.firstWhere((page) => page.pageId == pageId, orElse: () => null);
 
   @override
-  String toString() => '$runtimeType#${shortHash(this)}{pages=$pages}';
+  String toString() => '$runtimeType#${shortHash(this)}{uri=$uri, pages=$pages}';
 }
 
 class SinglePageInfo implements Comparable<SinglePageInfo> {

lib/services/metadata_service.dart

@@ -89,7 +89,7 @@ class MetadataService {
         'uri': entry.uri,
       });
       final pageMaps = (result as List).cast<Map>();
-      return MultiPageInfo.fromPageMaps(pageMaps);
+      return MultiPageInfo.fromPageMaps(entry.uri, pageMaps);
     } on PlatformException catch (e) {
       debugPrint('getMultiPageInfo failed with code=${e.code}, exception=${e.message}, details=${e.details}');
     }

lib/widgets/collection/grid/thumbnail.dart

@@ -43,7 +43,10 @@ class InteractiveThumbnail extends StatelessWidget {
           entry: entry,
           extent: tileExtent,
           collection: collection,
-          isScrollingNotifier: isScrollingNotifier,
+          // when the user is scrolling faster than we can retrieve the thumbnails,
+          // the retrieval task queue can pile up for thumbnails that got disposed
+          // in this case we pause the image retrieval task to get it out of the queue
+          cancellableNotifier: isScrollingNotifier,
         ),
       ),
     );

lib/widgets/collection/thumbnail/decorated.dart

@@ -9,7 +9,7 @@ class DecoratedThumbnail extends StatelessWidget {
   final AvesEntry entry;
   final double extent;
   final CollectionLens collection;
-  final ValueNotifier<bool> isScrollingNotifier;
+  final ValueNotifier<bool> cancellableNotifier;
   final bool selectable, highlightable;
 
   static final Color borderColor = Colors.grey.shade700;
@@ -20,7 +20,7 @@ class DecoratedThumbnail extends StatelessWidget {
     @required this.entry,
     @required this.extent,
     this.collection,
-    this.isScrollingNotifier,
+    this.cancellableNotifier,
     this.selectable = true,
     this.highlightable = true,
   }) : super(key: key);
@@ -40,7 +40,7 @@ class DecoratedThumbnail extends StatelessWidget {
         : RasterImageThumbnail(
             entry: entry,
             extent: extent,
-            isScrollingNotifier: isScrollingNotifier,
+            cancellableNotifier: cancellableNotifier,
             heroTag: heroTag,
           );
 

lib/widgets/collection/thumbnail/raster.dart

@@ -9,14 +9,14 @@ import 'package:flutter/material.dart';
 class RasterImageThumbnail extends StatefulWidget {
   final AvesEntry entry;
   final double extent;
-  final ValueNotifier<bool> isScrollingNotifier;
+  final ValueNotifier<bool> cancellableNotifier;
   final Object heroTag;
 
   const RasterImageThumbnail({
     Key key,
     @required this.entry,
     @required this.extent,
-    this.isScrollingNotifier,
+    this.cancellableNotifier,
     this.heroTag,
   }) : super(key: key);
 
@@ -70,11 +70,7 @@ class _RasterImageThumbnailState extends State<RasterImageThumbnail> {
   }
 
   void _pauseProvider() {
-    final isScrolling = widget.isScrollingNotifier?.value ?? false;
+    if (widget.cancellableNotifier?.value ?? false) {
-    // when the user is scrolling faster than we can retrieve the thumbnails,
-    // the retrieval task queue can pile up for thumbnails that got disposed
-    // in this case we pause the image retrieval task to get it out of the queue
-    if (isScrolling) {
       _fastThumbnailProvider?.pause();
       _sizedThumbnailProvider?.pause();
     }

lib/widgets/viewer/overlay/multipage.dart

@@ -27,6 +27,7 @@ class MultiPageOverlay extends StatefulWidget {
 }
 
 class _MultiPageOverlayState extends State<MultiPageOverlay> {
+  final _cancellableNotifier = ValueNotifier(true);
   ScrollController _scrollController;
   bool _syncScroll = true;
 
@@ -90,7 +91,8 @@ class _MultiPageOverlayState extends State<MultiPageOverlay> {
       future: controller.info,
       builder: (context, snapshot) {
         final multiPageInfo = snapshot.data;
-        if ((multiPageInfo?.pageCount ?? 0) <= 1) return SizedBox.shrink();
+        if ((multiPageInfo?.pageCount ?? 0) <= 1) return SizedBox();
+        if (multiPageInfo.uri != mainEntry.uri) return SizedBox();
         return Container(
           height: extent + separatorWidth * 2,
           child: Stack(
@@ -125,6 +127,10 @@ class _MultiPageOverlayState extends State<MultiPageOverlay> {
                       child: DecoratedThumbnail(
                         entry: pageEntry,
                         extent: extent,
+                        // the retrieval task queue can pile up for thumbnails of heavy pages
+                        // (e.g. thumbnails of 15MP HEIF images inside 100MB+ HEIC containers)
+                        // so we cancel these requests when possible
+                        cancellableNotifier: _cancellableNotifier,
                         selectable: false,
                         highlightable: false,
                       ),