♻️ Make delegate respect generic types as much as possible

example/lib/constants/picker_method.dart

@@ -207,10 +207,9 @@ class PickMethod {
                       return;
                     }
                     final picker = context.findAncestorWidgetOfExactType<
-                        AssetPicker<AssetEntity, AssetPathEntity>>()!;
-                    final builder =
-                        picker.builder as DefaultAssetPickerBuilderDelegate;
-                    final p = builder.provider;
+                        AssetPicker<AssetEntity, AssetPathEntity,
+                            DefaultAssetPickerBuilderDelegate>>()!;
+                    final p = picker.builder.provider;
                     await p.switchPath(
                       PathWrapper<AssetPathEntity>(
                         path:

example/lib/customs/pickers/directory_file_asset_picker.dart

@@ -163,7 +163,11 @@ class _DirectoryFileAssetPickerState extends State<DirectoryFileAssetPicker> {
     return GestureDetector(
       onTap: isDisplayingDetail
           ? () async {
-              final Widget viewer = AssetPickerViewer<File, Directory>(
+              final viewer = AssetPickerViewer<
+                  File,
+                  Directory,
+                  FileAssetPickerViewerProvider,
+                  FileAssetPickerViewerBuilderDelegate>(
                 builder: FileAssetPickerViewerBuilderDelegate(
                   currentIndex: index,
                   previewAssets: fileList,
@@ -392,7 +396,11 @@ class FileAssetPickerBuilder
           Animation<double> animation,
           Animation<double> secondaryAnimation,
         ) {
-          return AssetPickerViewer<File, Directory>(
+          return AssetPickerViewer<
+              File,
+              Directory,
+              FileAssetPickerViewerProvider,
+              FileAssetPickerViewerBuilderDelegate>(
             builder: FileAssetPickerViewerBuilderDelegate(
               currentIndex:
                   index ?? provider.selectedAssets.indexOf(currentAsset),
@@ -418,7 +426,8 @@ class FileAssetPickerBuilder
     List<File>? selectedAssets,
     FileAssetPickerProvider? selectorProvider,
   }) async {
-    final Widget viewer = AssetPickerViewer<File, Directory>(
+    final viewer = AssetPickerViewer<File, Directory,
+        FileAssetPickerViewerProvider, FileAssetPickerViewerBuilderDelegate>(
       builder: FileAssetPickerViewerBuilderDelegate(
         currentIndex: index,
         previewAssets: previewAssets,
@@ -1210,17 +1219,18 @@ class FileAssetPickerViewerProvider extends AssetPickerViewerProvider<File> {
 }
 
 class FileAssetPickerViewerBuilderDelegate
-    extends AssetPickerViewerBuilderDelegate<File, Directory> {
+    extends AssetPickerViewerBuilderDelegate<File, Directory,
+        FileAssetPickerViewerProvider> {
   FileAssetPickerViewerBuilderDelegate({
     required super.previewAssets,
     required super.themeData,
     required super.currentIndex,
     super.selectedAssets,
-    super.selectorProvider,
+    this.selectorProvider,
     super.provider,
-  }) : super(
-          maxAssets: selectorProvider?.maxAssets,
-        );
+  }) : super(maxAssets: selectorProvider?.maxAssets);
+
+  final FileAssetPickerProvider? selectorProvider;
 
   late final PageController _pageController = PageController(
     initialPage: currentIndex,

example/lib/customs/pickers/insta_asset_picker.dart

@@ -286,7 +286,8 @@ class _InstaAssetPickerState extends State<InstaAssetPicker> {
   }
 }
 
-class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
+class InstaAssetPickerBuilder<T extends DefaultAssetPickerProvider>
+    extends DefaultAssetPickerBuilderDelegate<T> {
   InstaAssetPickerBuilder({
     required super.provider,
     required super.initialPermission,
@@ -349,7 +350,7 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
   /// Initialize [_previewAsset] with [p.selectedAssets] if not empty
   /// otherwise if the first item of the album
   Future<void> _initializePreviewAsset(
-    DefaultAssetPickerProvider p,
+    T p,
     bool shouldDisplayAssets,
   ) async {
     if (_previewAsset.value != null) {
@@ -487,8 +488,8 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
             SizedBox(
           width: MediaQuery.sizeOf(context).width,
           height: previewHeight(context),
-          child: Selector<DefaultAssetPickerProvider, List<AssetEntity>>(
-            selector: (_, DefaultAssetPickerProvider p) => p.selectedAssets,
+          child: Selector<T, List<AssetEntity>>(
+            selector: (_, T p) => p.selectedAssets,
             builder: (_, List<AssetEntity> selected, __) {
               if (previewAsset == null && selected.isEmpty) {
                 return loadingIndicator(context);
@@ -502,7 +503,11 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
               final List<AssetEntity> assets =
                   selected.isEmpty ? <AssetEntity>[previewAsset!] : selected;
 
-              return AssetPickerViewer<AssetEntity, AssetPathEntity>(
+              return AssetPickerViewer<
+                  AssetEntity,
+                  AssetPathEntity,
+                  AssetPickerViewerProvider<AssetEntity>,
+                  InstaAssetPickerViewerBuilder>(
                 builder: InstaAssetPickerViewerBuilder(
                   currentIndex: effectiveIndex == -1 ? 0 : effectiveIndex,
                   previewAssets: assets,
@@ -541,7 +546,7 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
         _kPathSelectorRowHeight +
         MediaQuery.paddingOf(context).top;
 
-    return ChangeNotifierProvider<DefaultAssetPickerProvider>.value(
+    return ChangeNotifierProvider<T>.value(
       value: provider,
       builder: (BuildContext context, _) => ValueListenableBuilder<double>(
         valueListenable: _viewerPosition,
@@ -644,8 +649,8 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
 
   Widget _buildListAlbums(BuildContext context) {
     appBarPreferredSize ??= appBar(context).preferredSize;
-    return Consumer<DefaultAssetPickerProvider>(
-      builder: (BuildContext context, DefaultAssetPickerProvider provider, __) {
+    return Consumer<T>(
+      builder: (BuildContext context, T provider, __) {
         if (isAppleOS(context)) {
           return pathEntityListWidget(context);
         }
@@ -672,8 +677,8 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
 
   Widget _buildGrid(BuildContext context) {
     appBarPreferredSize ??= appBar(context).preferredSize;
-    return Consumer<DefaultAssetPickerProvider>(
-      builder: (BuildContext context, DefaultAssetPickerProvider p, __) {
+    return Consumer<T>(
+      builder: (BuildContext context, T p, __) {
         final bool shouldDisplayAssets =
             p.hasAssetsToDisplay || shouldBuildSpecialItem;
         _initializePreviewAsset(p, shouldDisplayAssets);

example/lib/customs/pickers/multi_tabs_assets_picker.dart

@@ -279,7 +279,10 @@ class MultiTabAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
   late final TabController _tabController;
 
   @override
-  void initState(AssetPickerState<AssetEntity, AssetPathEntity> state) {
+  void initState(
+    AssetPickerState<AssetEntity, AssetPathEntity, MultiTabAssetPickerBuilder>
+        state,
+  ) {
     super.initState(state);
     _tabController = TabController(length: 3, vsync: state);
   }

lib/builder.dart

@@ -0,0 +1,8 @@
+// Copyright 2019 The FlutterCandies author. All rights reserved.
+// Use of this source code is governed by an Apache license that can be found
+// in the LICENSE file.
+
+export 'src/widget/builder/asset_entity_grid_item_builder.dart';
+export 'src/widget/builder/audio_page_builder.dart';
+export 'src/widget/builder/image_page_builder.dart';
+export 'src/widget/builder/video_page_builder.dart';