Use version 0.4.0 photo_manager .

example/lib/asset_image.dart

     if (assetEntity == null) {
       return _buildContainer();
     }
-    return FutureBuilder<Size>(
-      builder: (c, s) {
-        if (!s.hasData) {
-          return Container();
+    final size = assetEntity.size;
+
+    print(
+        "assetEntity.width = ${assetEntity.width} , assetEntity.height = ${assetEntity.height}");
+
+    return FutureBuilder<Uint8List>(
+      builder: (BuildContext context, snapshot) {
+        if (snapshot.hasData) {
+          return _buildContainer(
+            child: Image.memory(
+              snapshot.data,
+              width: width,
+              height: height,
+              fit: boxFit,
+            ),
+          );
+        } else {
+          return _buildContainer();
         }
-        var size = s.data;
-        return FutureBuilder<Uint8List>(
-          builder: (BuildContext context, snapshot) {
-            if (snapshot.hasData) {
-              return _buildContainer(
-                child: Image.memory(
-                  snapshot.data,
-                  width: width,
-                  height: height,
-                  fit: boxFit,
-                ),
-              );
-            } else {
-              return _buildContainer();
-            }
-          },
-          future: assetEntity.thumbDataWithSize(
-            size.width.toInt(),
-            size.height.toInt(),
-          ),
-        );
       },
-      future: assetEntity.size,
+      future: assetEntity.thumbDataWithSize(
+        width.toInt(),
+        height.toInt(),
+      ),
     );
   }
 

lib/src/engine/throttle.dart

     this.duration = const Duration(seconds: 2),
   });
 
-  void call() {
+  void call(call) {
     if (!_isRunning) {
       _startTimer();
       onCall?.call();

lib/src/ui/dialog/change_gallery_dialog.dart

 
     return FlatButton(
       child: ListTile(
-        title: Text(text),
+        title: Text("$text (${entity.assetCount})"),
       ),
       onPressed: () {
         Navigator.pop(context, entity);

lib/src/ui/page/main/image_item.dart

       height: double.infinity,
       fit: BoxFit.cover,
     );
-    // FutureBuilder()
-    var badge = FutureBuilder<Duration>(
-      future: entity.videoDuration,
-      builder: (ctx, snapshot) {
-        if (snapshot.hasData && snapshot != null) {
-          var buildBadge =
-              badgeDelegate?.buildBadge(context, entity.type, snapshot.data);
-          if (buildBadge == null) {
-            return Container();
-          } else {
-            return buildBadge;
-          }
-        } else {
-          return Container();
-        }
-      },
-    );
+    var badge;
+    final badgeBuilder =
+        badgeDelegate?.buildBadge(context, entity.type, entity.videoDuration);
+    if (badgeBuilder == null) {
+      badge = Container();
+    } else {
+      badge = badgeBuilder;
+    }
 
     return Stack(
       children: <Widget>[

lib/src/ui/page/photo_main_page.dart

 
   Color get themeColor => options.themeColor;
 
-  AssetPathEntity _currentPath = AssetPathEntity.all;
+  AssetPathEntity _currentPath;
 
   bool _isInit = false;
 
   }
 
   String get currentGalleryName {
-    if (currentPath.isAll) {
+    if (currentPath?.isAll == true) {
       return i18nProvider.getAllGalleryText(options);
     }
-    return currentPath.name;
+    return currentPath?.name ?? "";
   }
 
   GlobalKey scaffoldKey;
     var v = await Navigator.of(context).push(
       MaterialPageRoute(
         builder: (ctx) => ConfigProvider(
-              provider: ConfigProvider.of(context).provider,
-              options: options,
-              child: PhotoPreviewPage(
-                selectedProvider: this,
-                list: List.of(selectedList),
-                changeProviderOnCheckChange: false,
-                result: result,
-              ),
-            ),
+          provider: ConfigProvider.of(context).provider,
+          options: options,
+          child: PhotoPreviewPage(
+            selectedProvider: this,
+            list: List.of(selectedList),
+            changeProviderOnCheckChange: false,
+            result: result,
+          ),
+        ),
       ),
     );
     if (handlePreviewResult(v)) {

pubspec.lock

 # Generated by pub
-# See https://www.dartlang.org/tools/pub/glossary#lockfile
+# See https://dart.dev/tools/pub/glossary#lockfile
 packages:
   async:
     dependency: transitive
       name: async
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.1.0"
+    version: "2.2.0"
   boolean_selector:
     dependency: transitive
     description:
       name: pedantic
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "1.5.0"
+    version: "1.7.0"
   photo_manager:
     dependency: "direct main"
     description:
-      name: photo_manager
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "0.3.4"
+      path: "."
+      ref: ffaa6e8470708e63c3456837c8bd6eef7b0d42df
+      resolved-ref: ffaa6e8470708e63c3456837c8bd6eef7b0d42df
+      url: "https://github.com/CaiJingLong/flutter_photo_manager.git"
+    source: git
+    version: "0.4.0"
   quiver:
     dependency: transitive
     description:
       name: quiver
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "2.0.2"
+    version: "2.0.3"
   sky_engine:
     dependency: transitive
     description: flutter
       name: test_api
       url: "https://pub.flutter-io.cn"
     source: hosted
-    version: "0.2.4"
+    version: "0.2.5"
   typed_data:
     dependency: transitive
     description:
     source: hosted
     version: "2.0.8"
 sdks:
-  dart: ">=2.2.0 <3.0.0"
+  dart: ">=2.2.2 <3.0.0"

pubspec.yaml

   flutter:
     sdk: flutter
 
-  photo_manager: ^0.3.4
-  # photo_manager:
-  #   git:
-  #     url: https://github.com/CaiJingLong/flutter_photo_manager.git
-  #     ref: 2e4821c1fa797272e4c454366b4fb264e8a054d6
+  # photo_manager: ^0.3.4
+  photo_manager:
+    git:
+      url: https://github.com/CaiJingLong/flutter_photo_manager.git
+      ref: ffaa6e8470708e63c3456837c8bd6eef7b0d42df
   # photo_manager:
   #   path: ../flutter_photo_manager