♻️ Improve AssetPickerViewerBuilderDelegate's abstraction

Author: AlexV525

example/lib/customs/pickers/directory_file_asset_picker.dart

@@ -1198,7 +1198,7 @@ class FileAssetPickerViewerBuilderDelegate
           maxAssets: selectorProvider?.maxAssets,
         );
 
-  bool isDisplayingDetail = true;
+  bool _isDisplayingDetail = true;
 
   late final AnimationController _doubleTapAnimationController;
   late final Animation<double> _doubleTapCurveAnimation;
@@ -1209,14 +1209,16 @@ class FileAssetPickerViewerBuilderDelegate
 
   AssetsPickerTextDelegate get textDelegate => AssetsPickerTextDelegate();
 
+  @override
   void switchDisplayingDetail({bool? value}) {
-    isDisplayingDetail = value ?? !isDisplayingDetail;
+    _isDisplayingDetail = value ?? !_isDisplayingDetail;
     if (viewerState.mounted) {
       // ignore: invalid_use_of_protected_member
       viewerState.setState(() {});
     }
   }
 
+  @override
   void updateAnimation(ExtendedImageGestureState state) {
     final double begin = state.gestureDetails!.totalScale!;
     final double end = state.gestureDetails!.totalScale! == 1.0 ? 3.0 : 1.0;
@@ -1240,13 +1242,6 @@ class FileAssetPickerViewerBuilderDelegate
     _doubleTapAnimationController.forward();
   }
 
-  Future<bool> syncSelectedAssetsWhenPop() async {
-    if (provider?.currentlySelectedAssets != null) {
-      selectorProvider?.selectedAssets = provider!.currentlySelectedAssets;
-    }
-    return true;
-  }
-
   @override
   Widget assetPageBuilder(BuildContext context, int index) {
     final File asset = previewAssets.elementAt(index);
@@ -1281,7 +1276,7 @@ class FileAssetPickerViewerBuilderDelegate
     return AnimatedPositioned(
       duration: kThemeAnimationDuration,
       curve: Curves.easeInOut,
-      bottom: isDisplayingDetail
+      bottom: _isDisplayingDetail
           ? 0.0
           : -(Screens.bottomSafeHeight + bottomDetailHeight),
       left: 0.0,
@@ -1395,7 +1390,7 @@ class FileAssetPickerViewerBuilderDelegate
     return AnimatedPositioned(
       duration: kThemeAnimationDuration,
       curve: Curves.easeInOut,
-      top: isDisplayingDetail ? 0.0 : -(Screens.topSafeHeight + kToolbarHeight),
+      top: _isDisplayingDetail ? 0.0 : -(Screens.topSafeHeight + kToolbarHeight),
       left: 0.0,
       right: 0.0,
       height: Screens.topSafeHeight + kToolbarHeight,

lib/src/delegates/asset_picker_viewer_builder_delegate.dart

@@ -60,6 +60,10 @@ abstract class AssetPickerViewerBuilderDelegate<Asset, Path> {
   /// 正在预览的资源的 [ScrollController]
   final ScrollController previewingListController = ScrollController();
 
+  /// Whether detail widgets displayed.
+  /// 详情部件是否显示
+  final ValueNotifier<bool> isDisplayingDetail = ValueNotifier<bool>(true);
+
   /// The [State] for a viewer.
   /// 预览器的状态实例
   late final AssetPickerViewerState<Asset, Path> viewerState;
@@ -115,8 +119,13 @@ abstract class AssetPickerViewerBuilderDelegate<Asset, Path> {
     pageStreamController.close();
     previewingListController.dispose();
     selectedNotifier.dispose();
+    isDisplayingDetail.dispose();
   }
 
+  /// Execute scale animation when double tap.
+  /// 双击时执行缩放动画
+  void updateAnimation(ExtendedImageGestureState state);
+
   /// The length getter for selected assets currently.
   /// 当前选中的资源的长度获取
   int get selectedCount => selectedAssets?.length ?? 0;
@@ -154,6 +163,21 @@ abstract class AssetPickerViewerBuilderDelegate<Asset, Path> {
     }
   }
 
+  /// Method to switch [isDisplayingDetail].
+  /// 切换显示详情状态的方法
+  void switchDisplayingDetail({bool? value}) {
+    isDisplayingDetail.value = value ?? !isDisplayingDetail.value;
+  }
+
+  /// Sync selected assets currently with asset picker provider.
+  /// 在预览中当前已选的图片同步到选择器的状态
+  Future<bool> syncSelectedAssetsWhenPop() async {
+    if (provider?.currentlySelectedAssets != null) {
+      selectorProvider?.selectedAssets = provider!.currentlySelectedAssets;
+    }
+    return true;
+  }
+
   /// Split page builder according to type of asset.
   /// 根据资源类型使用不同的构建页
   Widget assetPageBuilder(BuildContext context, int index);
@@ -270,10 +294,6 @@ class DefaultAssetPickerViewerBuilderDelegate
   late final PageController pageController =
       PageController(initialPage: currentIndex);
 
-  /// Whether detail widgets displayed.
-  /// 详情部件是否显示
-  final ValueNotifier<bool> isDisplayingDetail = ValueNotifier<bool>(true);
-
   /// Whether the [SpecialPickerType.wechatMoment] is enabled.
   /// 当前是否为微信朋友圈选择模式
   bool get isWeChatMoment =>
@@ -309,8 +329,7 @@ class DefaultAssetPickerViewerBuilderDelegate
     super.dispose();
   }
 
-  /// Execute scale animation when double tap.
-  /// 双击时执行缩放动画
+  @override
   void updateAnimation(ExtendedImageGestureState state) {
     final double begin = state.gestureDetails!.totalScale!;
     final double end = state.gestureDetails!.totalScale! == 1.0 ? 3.0 : 1.0;
@@ -334,52 +353,35 @@ class DefaultAssetPickerViewerBuilderDelegate
     _doubleTapAnimationController.forward();
   }
 
-  /// Method to switch [isDisplayingDetail].
-  /// 切换显示详情状态的方法
-  void switchDisplayingDetail({bool? value}) {
-    isDisplayingDetail.value = value ?? !isDisplayingDetail.value;
-  }
-
-  /// Sync selected assets currently with asset picker provider.
-  /// 在预览中当前已选的图片同步到选择器的状态
-  Future<bool> syncSelectedAssetsWhenPop() async {
-    if (provider?.currentlySelectedAssets != null) {
-      selectorProvider?.selectedAssets = provider!.currentlySelectedAssets;
-    }
-    return true;
-  }
-
   @override
   Widget assetPageBuilder(BuildContext context, int index) {
     final AssetEntity asset = previewAssets.elementAt(index);
-    Widget builder;
+    Widget _builder;
     switch (asset.type) {
       case AssetType.audio:
-        builder = AudioPageBuilder(asset: asset, state: viewerState);
+        _builder = AudioPageBuilder(asset: asset);
         break;
       case AssetType.image:
-        builder = ImagePageBuilder(
+        _builder = ImagePageBuilder(
           asset: asset,
-          state: viewerState,
+          delegate: this,
           previewThumbSize: previewThumbSize,
         );
         break;
       case AssetType.video:
-        builder = VideoPageBuilder(
+        _builder = VideoPageBuilder(
           asset: asset,
-          state: viewerState,
+          delegate: this,
           hasOnlyOneVideoAndMoment: isWeChatMoment && hasVideo,
         );
         break;
       case AssetType.other:
-        builder = Center(
-          child: ScaleText(
-            Constants.textDelegate.unSupportedAssetType,
-          ),
+        _builder = Center(
+          child: ScaleText(Constants.textDelegate.unSupportedAssetType),
         );
         break;
     }
-    return builder;
+    return _builder;
   }
 
   /// Preview item widgets for audios.

lib/src/widget/builder/audio_page_builder.dart

@@ -10,20 +10,12 @@ import '../../../src/constants/constants.dart';
 import '../scale_text.dart';
 
 class AudioPageBuilder extends StatefulWidget {
-  const AudioPageBuilder({
-    Key? key,
-    required this.asset,
-    required this.state,
-  }) : super(key: key);
+  const AudioPageBuilder({Key? key, required this.asset}) : super(key: key);
 
   /// Asset currently displayed.
   /// 展示的资源
   final AssetEntity asset;
 
-  /// [State] for asset picker viewer.
-  /// 资源查看器的状态 [State]
-  final AssetPickerViewerState<AssetEntity, AssetPathEntity> state;
-
   @override
   State<StatefulWidget> createState() => _AudioPageBuilderState();
 }

lib/src/widget/builder/image_page_builder.dart

@@ -12,17 +12,15 @@ class ImagePageBuilder extends StatefulWidget {
   const ImagePageBuilder({
     Key? key,
     required this.asset,
-    required this.state,
+    required this.delegate,
     this.previewThumbSize,
   }) : super(key: key);
 
   /// Asset currently displayed.
   /// 展示的资源
   final AssetEntity asset;
 
-  /// [State] for asset picker viewer.
-  /// 资源查看器的状态[State]
-  final AssetPickerViewerState<AssetEntity, AssetPathEntity> state;
+  final AssetPickerViewerBuilderDelegate<AssetEntity, AssetPathEntity> delegate;
 
   final List<int>? previewThumbSize;
 
@@ -31,9 +29,6 @@ class ImagePageBuilder extends StatefulWidget {
 }
 
 class _ImagePageBuilderState extends State<ImagePageBuilder> {
-  DefaultAssetPickerViewerBuilderDelegate get builder =>
-      widget.state.builder as DefaultAssetPickerViewerBuilderDelegate;
-
   @override
   Widget build(BuildContext context) {
     return LocallyAvailableBuilder(
@@ -42,7 +37,7 @@ class _ImagePageBuilderState extends State<ImagePageBuilder> {
       builder: (BuildContext context, AssetEntity asset) {
         return GestureDetector(
           behavior: HitTestBehavior.opaque,
-          onTap: builder.switchDisplayingDetail,
+          onTap: widget.delegate.switchDisplayingDetail,
           child: ExtendedImage(
             image: AssetEntityImageProvider(
               asset,
@@ -51,7 +46,7 @@ class _ImagePageBuilderState extends State<ImagePageBuilder> {
             ),
             fit: BoxFit.contain,
             mode: ExtendedImageMode.gesture,
-            onDoubleTap: builder.updateAnimation,
+            onDoubleTap: widget.delegate.updateAnimation,
             initGestureConfigHandler: (ExtendedImageState state) {
               return GestureConfig(
                 initialScale: 1.0,
@@ -64,7 +59,7 @@ class _ImagePageBuilderState extends State<ImagePageBuilder> {
               );
             },
             loadStateChanged: (ExtendedImageState state) {
-              return builder.previewWidgetLoadStateChanged(
+              return widget.delegate.previewWidgetLoadStateChanged(
                 context,
                 state,
                 hasLoaded: state.extendedImageLoadState == LoadState.completed,

lib/src/widget/builder/video_page_builder.dart

@@ -13,17 +13,15 @@ class VideoPageBuilder extends StatefulWidget {
   const VideoPageBuilder({
     Key? key,
     required this.asset,
-    required this.state,
+    required this.delegate,
     this.hasOnlyOneVideoAndMoment = false,
   }) : super(key: key);
 
   /// Asset currently displayed.
   /// 展示的资源
   final AssetEntity asset;
 
-  /// [State] for asset picker viewer.
-  /// 资源查看器的状态 [State]
-  final AssetPickerViewerState<AssetEntity, AssetPathEntity> state;
+  final AssetPickerViewerBuilderDelegate<AssetEntity, AssetPathEntity> delegate;
 
   /// Only previewing one video and with the [SpecialPickerType.wechatMoment].
   /// 是否处于 [SpecialPickerType.wechatMoment] 且只有一个视频
@@ -54,9 +52,6 @@ class _VideoPageBuilderState extends State<VideoPageBuilder> {
   /// 播放控制器是否在播放
   bool get isControllerPlaying => _controller.value.isPlaying;
 
-  DefaultAssetPickerViewerBuilderDelegate get builder =>
-      widget.state.builder as DefaultAssetPickerViewerBuilderDelegate;
-
   @override
   void initState() {
     super.initState();
@@ -122,8 +117,8 @@ class _VideoPageBuilderState extends State<VideoPageBuilder> {
     if (isPlaying.value) {
       _controller.pause();
     } else {
-      if (builder.isDisplayingDetail.value) {
-        builder.switchDisplayingDetail(value: false);
+      if (widget.delegate.isDisplayingDetail.value) {
+        widget.delegate.switchDisplayingDetail(value: false);
       }
       if (_controller.value.duration == _controller.value.position) {
         _controller
@@ -164,7 +159,7 @@ class _VideoPageBuilderState extends State<VideoPageBuilder> {
                   behavior: HitTestBehavior.opaque,
                   onTap: value
                       ? playButtonCallback
-                      : builder.switchDisplayingDetail,
+                      : widget.delegate.switchDisplayingDetail,
                   child: Center(
                     child: AnimatedOpacity(
                       duration: kThemeAnimationDuration,