♻️ Take out things that belongs to the builder.

Author: AlexV525

lib/src/delegates/asset_picker_builder_delegate.dart

@@ -19,6 +19,8 @@ abstract class AssetPickerBuilderDelegate<A, P> {
     Color themeColor,
     AssetsPickerTextDelegate textDelegate,
     this.pickerTheme,
+    this.customItemPosition = CustomItemPosition.none,
+    this.customItemBuilder,
   })  : assert(
           pickerTheme == null || themeColor == null,
           'Theme and theme color cannot be set at the same time.',
@@ -50,6 +52,14 @@ abstract class AssetPickerBuilderDelegate<A, P> {
   /// 通常情况下微信选择器使用的是暗色（暗色背景）的主题，但某些情况下开发者需要亮色或自定义主题。
   final ThemeData pickerTheme;
 
+  /// Allow users set custom item in the picker with several positions.
+  /// 允许用户在选择器中添加一个自定义item，并指定位置。
+  final CustomItemPosition customItemPosition;
+
+  /// The widget builder for the custom item.
+  /// 自定义item的构造方法
+  final WidgetBuilder customItemBuilder;
+
   /// [ThemeData] for the picker.
   /// 选择器使用的主题
   ThemeData get theme => pickerTheme ?? AssetPicker.themeData(themeColor);
@@ -387,10 +397,10 @@ class DefaultAssetPickerBuilderDelegate
     Color themeColor,
     AssetsPickerTextDelegate textDelegate,
     ThemeData pickerTheme,
+    CustomItemPosition customItemPosition = CustomItemPosition.none,
+    WidgetBuilder customItemBuilder,
     this.previewThumbSize,
     this.specialPickerType,
-    this.customItemPosition = CustomItemPosition.none,
-    this.customItemBuilder,
   })  : assert(
           provider != null,
           'AssetPickerProvider must be provided and not null.',
@@ -405,6 +415,8 @@ class DefaultAssetPickerBuilderDelegate
           themeColor: themeColor,
           textDelegate: textDelegate,
           pickerTheme: pickerTheme,
+          customItemPosition: customItemPosition,
+          customItemBuilder: customItemBuilder,
         );
 
   /// Thumb size for the preview of images in the viewer.
@@ -431,14 +443,6 @@ class DefaultAssetPickerBuilderDelegate
   /// * [SpecialPickerType.wechatMoment] 微信朋友圈模式。当用户选择了视频，将不能选择图片。
   final SpecialPickerType specialPickerType;
 
-  /// The widget builder for the custom item.
-  /// 自定义item的构造方法
-  final WidgetBuilder customItemBuilder;
-
-  /// Allow users set custom item in the picker with several positions.
-  /// 允许用户在选择器中添加一个自定义item，并指定位置。
-  final CustomItemPosition customItemPosition;
-
   /// [Duration] when triggering path switching.
   /// 切换路径时的动画时长
   Duration get switchingPathDuration => kThemeAnimationDuration * 1.5;
@@ -570,10 +574,11 @@ class DefaultAssetPickerBuilderDelegate
     int index,
     List<AssetEntity> currentAssets,
   ) {
-    final AssetPathEntity currentPath = Provider.of<DefaultAssetPickerProvider>(
+    final AssetPathEntity currentPathEntity =
+        Provider.of<DefaultAssetPickerProvider>(
       context,
       listen: false,
-    ).currentPath;
+    ).currentPathEntity;
 
     int currentIndex;
     switch (customItemPosition) {
@@ -585,7 +590,7 @@ class DefaultAssetPickerBuilderDelegate
         currentIndex = index - 1;
         break;
     }
-    if (!currentPath.isAll) {
+    if (!currentPathEntity.isAll) {
       currentIndex = index;
     }
 
@@ -594,7 +599,7 @@ class DefaultAssetPickerBuilderDelegate
       provider.loadMoreAssets();
     }
 
-    if (currentPath.isAll) {
+    if (currentPathEntity.isAll) {
       if ((index == currentAssets.length &&
               customItemPosition == CustomItemPosition.append) ||
           (index == 0 && customItemPosition == CustomItemPosition.prepend)) {
@@ -631,14 +636,15 @@ class DefaultAssetPickerBuilderDelegate
     BuildContext context,
     List<AssetEntity> currentAssets,
   ) {
-    final AssetPathEntity currentPath = Provider.of<DefaultAssetPickerProvider>(
+    final AssetPathEntity currentPathEntity =
+        Provider.of<DefaultAssetPickerProvider>(
       context,
       listen: false,
-    ).currentPath;
+    ).currentPathEntity;
 
     /// 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。
-    if (!currentPath.isAll) {
+    if (!currentPathEntity.isAll) {
       return currentAssets.length;
     }
     int length;
@@ -867,9 +873,8 @@ class DefaultAssetPickerBuilderDelegate
           ignoring: !isSwitchingPath,
           child: GestureDetector(
             onTap: () {
-              context
-                  .read<AssetPickerProvider<AssetEntity, AssetPathEntity>>()
-                  .isSwitchingPath = false;
+              context.read<DefaultAssetPickerProvider>().isSwitchingPath =
+                  false;
             },
             child: AnimatedOpacity(
               duration: switchingPathDuration,
@@ -977,10 +982,10 @@ class DefaultAssetPickerBuilderDelegate
               child: Row(
                 mainAxisSize: MainAxisSize.min,
                 children: <Widget>[
-                  if (provider.currentPath != null)
+                  if (provider.currentPathEntity != null)
                     Flexible(
                       child: Text(
-                        provider.currentPath.name ?? '',
+                        provider.currentPathEntity.name ?? '',
                         style: const TextStyle(
                           fontSize: 18.0,
                           fontWeight: FontWeight.normal,
@@ -1107,7 +1112,7 @@ class DefaultAssetPickerBuilderDelegate
                   BuildContext _,
                   DefaultAssetPickerProvider provider,
                 ) =>
-                    provider.currentPath,
+                    provider.currentPathEntity,
                 builder: (
                   BuildContext _,
                   AssetPathEntity currentPathEntity,

lib/src/provider/asset_picker_provider.dart

@@ -19,17 +19,10 @@ abstract class AssetPickerProvider<A, P> extends ChangeNotifier {
     this.pageSize = 320,
     this.pathThumbSize = 80,
     List<A> selectedAssets,
-    Duration routeDuration,
   }) {
     if (selectedAssets?.isNotEmpty ?? false) {
       _selectedAssets = List<A>.from(selectedAssets);
     }
-    Future<void>.delayed(routeDuration).then(
-      (dynamic _) async {
-        await getAssetPathList();
-        await getAssetList();
-      },
-    );
   }
 
   /// Maximum count for asset selection.
@@ -51,7 +44,7 @@ abstract class AssetPickerProvider<A, P> extends ChangeNotifier {
     _isAssetsEmpty = false;
     _isSwitchingPath = false;
     _pathEntityList.clear();
-    _currentPath = null;
+    _currentPathEntity = null;
     _currentAssets = null;
     _selectedAssets.clear();
     super.dispose();
@@ -136,16 +129,16 @@ abstract class AssetPickerProvider<A, P> extends ChangeNotifier {
 
   /// The path which is currently using.
   /// 正在查看的资源路径
-  P _currentPath;
+  P _currentPathEntity;
 
-  P get currentPath => _currentPath;
+  P get currentPathEntity => _currentPathEntity;
 
   set currentPathEntity(P value) {
     assert(value != null);
-    if (value == _currentPath) {
+    if (value == _currentPathEntity) {
       return;
     }
-    _currentPath = value;
+    _currentPathEntity = value;
     notifyListeners();
   }
 
@@ -186,17 +179,13 @@ abstract class AssetPickerProvider<A, P> extends ChangeNotifier {
   /// 获取所有的资源路径
   Future<void> getAssetPathList();
 
-  /// Get assets list from current path entity.
-  /// 从当前已选路径获取资源列表
-  Future<void> getAssetList();
-
   /// Get thumb data from the first asset under the specific path entity.
   /// 获取指定路径下的第一个资源的缩略数据
-  Future<Uint8List> getFirstThumbFromPathEntity(P path);
+  Future<Uint8List> getFirstThumbFromPathEntity(P pathEntity);
 
   /// Get assets under the specific path entity.
   /// 获取指定路径下的资源
-  Future<void> getAssetsFromEntity(int page, P path);
+  Future<void> getAssetsFromEntity(int page, P pathEntity);
 
   /// Load more assets.
   /// 加载更多资源
@@ -223,7 +212,7 @@ abstract class AssetPickerProvider<A, P> extends ChangeNotifier {
 
   /// Switch path entity.
   /// 切换路径
-  void switchPath(P path);
+  void switchPath(P pathEntity);
 }
 
 class DefaultAssetPickerProvider
@@ -242,9 +231,14 @@ class DefaultAssetPickerProvider
           pageSize: pageSize,
           pathThumbSize: pathThumbSize,
           selectedAssets: selectedAssets,
-          routeDuration: routeDuration,
         ) {
     Constants.sortPathDelegate = sortPathDelegate ?? SortPathDelegate.common;
+    Future<void>.delayed(routeDuration).then(
+      (dynamic _) async {
+        await getAssetPathList();
+        await getAssetList();
+      },
+    );
   }
 
   /// Request assets type.
@@ -304,34 +298,37 @@ class DefaultAssetPickerProvider
 
     /// Set first path entity as current path entity.
     if (_pathEntityList.isNotEmpty) {
-      _currentPath ??= pathEntityList.keys.elementAt(0);
+      _currentPathEntity ??= pathEntityList.keys.elementAt(0);
     }
   }
 
-  @override
+  /// Get assets list from current path entity.
+  /// 从当前已选路径获取资源列表
   Future<void> getAssetList() async {
     if (_pathEntityList.isNotEmpty) {
-      _currentPath = pathEntityList.keys.elementAt(0);
-      totalAssetsCount = currentPath.assetCount;
-      await getAssetsFromEntity(0, currentPath);
+      _currentPathEntity = _pathEntityList.keys.elementAt(0);
+      totalAssetsCount = currentPathEntity.assetCount;
+      await getAssetsFromEntity(0, currentPathEntity);
       // Update total assets count.
     } else {
       isAssetsEmpty = true;
     }
   }
 
   @override
-  Future<void> getAssetsFromEntity(int page, AssetPathEntity path) async {
-    _currentAssets =
-        (await path.getAssetListPaged(page, pageSize ?? path.assetCount))
-            .toList();
+  Future<void> getAssetsFromEntity(int page, AssetPathEntity pathEntity) async {
+    _currentAssets = (await pathEntity.getAssetListPaged(
+      page,
+      pageSize ?? pathEntity.assetCount,
+    ))
+        .toList();
     _hasAssetsToDisplay = currentAssets?.isNotEmpty ?? false;
     notifyListeners();
   }
 
   @override
   Future<void> loadMoreAssets() async {
-    final List<AssetEntity> assets = (await currentPath.getAssetListPaged(
+    final List<AssetEntity> assets = (await currentPathEntity.getAssetListPaged(
       currentAssetsListPage,
       pageSize,
     ))
@@ -347,18 +344,23 @@ class DefaultAssetPickerProvider
   }
 
   @override
-  void switchPath(AssetPathEntity path) {
+  void switchPath(AssetPathEntity pathEntity) {
     _isSwitchingPath = false;
-    _currentPath = path;
-    _totalAssetsCount = path.assetCount;
+    _currentPathEntity = pathEntity;
+    _totalAssetsCount = pathEntity.assetCount;
     notifyListeners();
-    getAssetsFromEntity(0, currentPath);
+    getAssetsFromEntity(0, currentPathEntity);
   }
 
   @override
-  Future<Uint8List> getFirstThumbFromPathEntity(AssetPathEntity path) async {
-    final AssetEntity asset =
-        (await path.getAssetListRange(start: 0, end: 1)).elementAt(0);
+  Future<Uint8List> getFirstThumbFromPathEntity(
+    AssetPathEntity pathEntity,
+  ) async {
+    final AssetEntity asset = (await pathEntity.getAssetListRange(
+      start: 0,
+      end: 1,
+    ))
+        .elementAt(0);
     final Uint8List assetData =
         await asset.thumbDataWithSize(pathThumbSize, pathThumbSize);
     return assetData;