⚡ Improve assets viewing (#605)

CHANGELOG.md

@@ -7,6 +7,15 @@ that can be found in the LICENSE file. -->
 > [!IMPORTANT]  
 > See the [Migration Guide](guides/migration_guide.md) for the details of breaking changes between versions.
 
+## Unreleased
+
+### Fixes
+
+- Raise detailed negative range error.
+- Fix viewer confirm button predication.
+- Enlarge GIF gradients.
+- Fix potential paths assets count unexpected merging behaviors.
+
 ## 9.1.0
 
 ### Improvements

lib/src/delegates/asset_picker_builder_delegate.dart

@@ -389,10 +389,10 @@ abstract class AssetPickerBuilderDelegate<Asset, Path> {
   /// GIF image type indicator.
   /// GIF 类型图片指示
   Widget gifIndicator(BuildContext context, Asset asset) {
-    return PositionedDirectional(
-      start: 0,
-      bottom: 0,
+    return Positioned.fill(
+      top: null,
       child: Container(
+        alignment: AlignmentDirectional.centerEnd,
         padding: const EdgeInsets.all(6),
         decoration: BoxDecoration(
           gradient: LinearGradient(

lib/src/delegates/asset_picker_viewer_builder_delegate.dart

@@ -814,10 +814,9 @@ class DefaultAssetPickerViewerBuilderDelegate
             return textDelegate.confirm;
           }
 
-          final bool isButtonEnabled = provider == null ||
-              provider.currentlySelectedAssets.isNotEmpty ||
+          final isButtonEnabled = provider == null ||
               previewAssets.isEmpty ||
-              selectedNotifier.value == 0;
+              (selectedAssets?.isNotEmpty ?? false);
           return MaterialButton(
             minWidth:
                 (isWeChatMoment && hasVideo) || provider!.isSelectedNotEmpty
@@ -920,9 +919,23 @@ class DefaultAssetPickerViewerBuilderDelegate
         stream: pageStreamController.stream,
         builder: (_, s) {
           final index = s.data!;
-          final AssetEntity asset = previewAssets.elementAt(
-            shouldReversePreview ? previewAssets.length - index - 1 : index,
-          );
+          final assetIndex =
+              shouldReversePreview ? previewAssets.length - index - 1 : index;
+          if (assetIndex < 0) {
+            throw IndexError.withLength(
+              assetIndex,
+              previewAssets.length,
+              indexable: previewAssets,
+              name: 'selectButton.assetIndex',
+              message: 'previewReversed: $shouldReversePreview\n'
+                  'stream.index: $index\n'
+                  'selectedAssets.length: ${selectedAssets?.length}\n'
+                  'previewAssets.length: ${previewAssets.length}\n'
+                  'currentIndex: $currentIndex\n'
+                  'maxAssets: $maxAssets',
+            );
+          }
+          final asset = previewAssets.elementAt(assetIndex);
           return Selector<AssetPickerViewerProvider<AssetEntity>,
               List<AssetEntity>>(
             selector: (_, p) => p.currentlySelectedAssets,

lib/src/provider/asset_picker_provider.dart

@@ -365,10 +365,13 @@ class DefaultAssetPickerProvider
     _paths = list.map((p) => PathWrapper<AssetPathEntity>(path: p)).toList();
     // Sort path using sort path delegate.
     Singleton.sortPathDelegate.sort(_paths);
-    // Use sync method to avoid unnecessary wait.
-    _paths
-      ..forEach(getAssetCountFromPath)
-      ..forEach(getThumbnailFromPath);
+    // Populate fields to paths without awaiting.
+    for (final path in _paths) {
+      Future(() async {
+        await getAssetCountFromPath(path);
+        await getThumbnailFromPath(path);
+      });
+    }
 
     // Set first path entity as current path entity.
     if (_paths.isNotEmpty) {
@@ -479,7 +482,10 @@ class DefaultAssetPickerProvider
         (PathWrapper<AssetPathEntity> p) => p.path == path.path,
       );
       if (index != -1) {
-        _paths[index] = _paths[index].copyWith(thumbnailData: data);
+        _paths[index] = _paths[index].copyWith(
+          assetCount: assetCount,
+          thumbnailData: data,
+        );
         notifyListeners();
       }
       return data;