🚸 Update how paths get update (#312)

Author: AlexV525

lib/src/delegates/asset_picker_builder_delegate.dart

@@ -810,10 +810,33 @@ class DefaultAssetPickerBuilderDelegate
       return;
     }
     final AssetPathEntity? _currentPathEntity = provider.currentPath;
+    if (call.arguments is Map) {
+      final Map<dynamic, dynamic> arguments =
+          call.arguments as Map<dynamic, dynamic>;
+      if (arguments['newCount'] == 0) {
+        provider
+          ..currentAssets = <AssetEntity>[]
+          ..currentPath = null
+          ..hasAssetsToDisplay = false
+          ..isAssetsEmpty = true;
+        return;
+      }
+      if (_currentPathEntity == null) {
+        await provider.getPaths();
+      }
+    }
     if (_currentPathEntity != null) {
-      provider.currentPath = await _currentPathEntity.obtainForNewProperties();
-      await provider.switchPath(_currentPathEntity);
+      final AssetPathEntity newPath =
+          await _currentPathEntity.obtainForNewProperties();
+      provider
+        ..currentPath = newPath
+        ..hasAssetsToDisplay = newPath.assetCount != 0
+        ..isAssetsEmpty = newPath.assetCount == 0
+        ..totalAssetsCount = newPath.assetCount;
       isSwitchingPath.value = false;
+      if (newPath.isAll) {
+        await provider.getAssetsFromCurrentPath();
+      }
     }
   }
 
@@ -1375,7 +1398,7 @@ class DefaultAssetPickerBuilderDelegate
     /// Return actual length if current path is all.
     /// 如果当前目录是全部内容，则返回实际的内容数量。
     final int _length = assets.length + placeholderCount;
-    if (!currentPathEntity!.isAll) {
+    if (currentPathEntity?.isAll != true) {
       return _length;
     }
     switch (specialItemPosition) {
@@ -1679,10 +1702,34 @@ class DefaultAssetPickerBuilderDelegate
 
   @override
   Widget pathEntitySelector(BuildContext context) {
+    Widget _text(
+      BuildContext context,
+      String text,
+      String semanticsText,
+    ) {
+      return Flexible(
+        child: ScaleText(
+          text,
+          style: const TextStyle(
+            fontSize: 17,
+            fontWeight: FontWeight.normal,
+          ),
+          maxLines: 1,
+          overflow: TextOverflow.fade,
+          maxScaleFactor: 1.2,
+          semanticsLabel: semanticsText,
+        ),
+      );
+    }
+
     return UnconstrainedBox(
       child: GestureDetector(
         onTap: () {
           Feedback.forTap(context);
+          if (isPermissionLimited && provider.isAssetsEmpty) {
+            PhotoManager.presentLimited();
+            return;
+          }
           isSwitchingPath.value = !isSwitchingPath.value;
         },
         child: Container(
@@ -1700,23 +1747,21 @@ class DefaultAssetPickerBuilderDelegate
             builder: (_, AssetPathEntity? p, Widget? w) => Row(
               mainAxisSize: MainAxisSize.min,
               children: <Widget>[
+                if (p == null && isPermissionLimited)
+                  _text(
+                    context,
+                    textDelegate.changeAccessibleLimitedAssets,
+                    semanticsTextDelegate.changeAccessibleLimitedAssets,
+                  ),
                 if (p != null)
-                  Flexible(
-                    child: ScaleText(
-                      isPermissionLimited && p.isAll
-                          ? textDelegate.accessiblePathName
-                          : pathNameBuilder?.call(p) ?? p.name,
-                      style: const TextStyle(
-                        fontSize: 17,
-                        fontWeight: FontWeight.normal,
-                      ),
-                      maxLines: 1,
-                      overflow: TextOverflow.ellipsis,
-                      maxScaleFactor: 1.2,
-                      semanticsLabel: isPermissionLimited && p.isAll
-                          ? semanticsTextDelegate.accessiblePathName
-                          : pathNameBuilder?.call(p) ?? p.name,
-                    ),
+                  _text(
+                    context,
+                    isPermissionLimited && p.isAll
+                        ? textDelegate.accessiblePathName
+                        : pathNameBuilder?.call(p) ?? p.name,
+                    isPermissionLimited && p.isAll
+                        ? semanticsTextDelegate.accessiblePathName
+                        : pathNameBuilder?.call(p) ?? p.name,
                   ),
                 w!,
               ],

lib/src/provider/asset_picker_provider.dart

@@ -155,7 +155,7 @@ abstract class AssetPickerProvider<Asset, Path> extends ChangeNotifier {
   Path? _currentPath;
 
   set currentPath(Path? value) {
-    if (value == null || value == _currentPath) {
+    if (value == _currentPath) {
       return;
     }
     _currentPath = value;
@@ -282,6 +282,30 @@ class DefaultAssetPickerProvider
   /// 将会与基础条件进行合并。
   final FilterOptionGroup? filterOptions;
 
+  @override
+  set currentPath(AssetPathEntity? value) {
+    if (value == _currentPath) {
+      return;
+    }
+    _currentPath = value;
+    if (value != null &&
+        _pathsList.keys.any((AssetPathEntity p) => p.id == value.id)) {
+      final AssetPathEntity previous = _pathsList.keys.singleWhere(
+        (AssetPathEntity p) => p.id == value.id,
+      );
+      final int index = _pathsList.keys.toList().indexOf(previous);
+      final List<MapEntry<AssetPathEntity, Uint8List?>> newEntries =
+          _pathsList.entries.toList()
+            ..removeAt(index)
+            ..insert(index, MapEntry<AssetPathEntity, Uint8List?>(value, null));
+      _pathsList
+        ..clear()
+        ..addEntries(newEntries);
+      getThumbnailFromPath(value);
+    }
+    notifyListeners();
+  }
+
   @override
   Future<void> getPaths() async {
     // Initial base options.
@@ -314,12 +338,7 @@ class DefaultAssetPickerProvider
     for (final AssetPathEntity pathEntity in _list) {
       // Use sync method to avoid unnecessary wait.
       _pathsList[pathEntity] = null;
-      if (requestType != RequestType.audio) {
-        getThumbnailFromPath(pathEntity).then((Uint8List? data) {
-          _pathsList[pathEntity] = data;
-          notifyListeners();
-        });
-      }
+      getThumbnailFromPath(pathEntity);
     }
 
     // Set first path entity as current path entity.
@@ -402,6 +421,9 @@ class DefaultAssetPickerProvider
         return true;
       }(),
     );
+    if (requestType == RequestType.audio) {
+      return null;
+    }
     final List<AssetEntity> assets = await path.getAssetListRange(
       start: 0,
       end: 1,
@@ -417,14 +439,15 @@ class DefaultAssetPickerProvider
     final Uint8List? assetData = await asset.thumbnailDataWithSize(
       pathThumbnailSize,
     );
+    _pathsList[path] = assetData;
+    notifyListeners();
     return assetData;
   }
 
   /// Get assets list from current path entity.
   /// 从当前已选路径获取资源列表
   Future<void> getAssetsFromCurrentPath() async {
     if (_pathsList.isNotEmpty) {
-      _currentPath = _pathsList.keys.elementAt(0);
       totalAssetsCount = currentPath!.assetCount;
       await getAssetsFromPath(0, currentPath!);
     } else {