♻️ Make delegate respect generic types as much as possible (#639)

We have `Asset` and `Path` generic abstractions, but we didn't consider the delegate's generic abstractions. They are necessary when building delegates that rely on custom data source providers.

Author: AlexV525

CHANGELOG.md

@@ -9,7 +9,8 @@ that can be found in the LICENSE file. -->
 
 ## Unreleased
 
-*None.*
+- Make delegate respect generic types as much as possible.
+  This is a breaking change for users who use custom delegates and providers.
 
 ## 9.6.0
 

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

@@ -163,18 +163,19 @@ class _DirectoryFileAssetPickerState extends State<DirectoryFileAssetPicker> {
     return GestureDetector(
       onTap: isDisplayingDetail
           ? () async {
-              final Widget viewer = AssetPickerViewer<File, Directory>(
-                builder: FileAssetPickerViewerBuilderDelegate(
+              final result = await AssetPickerViewer.pushToViewerWithDelegate<
+                  File,
+                  Directory,
+                  FileAssetPickerViewerProvider,
+                  FileAssetPickerViewerBuilderDelegate>(
+                context,
+                delegate: FileAssetPickerViewerBuilderDelegate(
                   currentIndex: index,
                   previewAssets: fileList,
                   provider: FileAssetPickerViewerProvider(fileList),
                   themeData: AssetPicker.themeData(themeColor),
                 ),
               );
-              final List<File>? result =
-                  await Navigator.maybeOf(context)?.push<List<File>>(
-                AssetPickerViewerPageRoute(builder: (context) => viewer),
-              );
               if (result != null && result != fileList) {
                 fileList
                   ..clear()
@@ -261,7 +262,8 @@ class _DirectoryFileAssetPickerState extends State<DirectoryFileAssetPicker> {
   }
 }
 
-class FileAssetPickerProvider extends AssetPickerProvider<File, Directory> {
+final class FileAssetPickerProvider
+    extends AssetPickerProvider<File, Directory> {
   FileAssetPickerProvider({
     required List<File> selectedAssets,
   }) : super(selectedAssets: selectedAssets) {
@@ -346,7 +348,7 @@ class FileAssetPickerProvider extends AssetPickerProvider<File, Directory> {
   }
 }
 
-class FileAssetPickerBuilder
+final class FileAssetPickerBuilder
     extends AssetPickerBuilderDelegate<File, Directory> {
   FileAssetPickerBuilder({
     required this.provider,
@@ -368,8 +370,13 @@ class FileAssetPickerBuilder
     int? index,
     File currentAsset,
   ) async {
-    final Widget viewer = AssetPickerViewer<File, Directory>(
-      builder: FileAssetPickerViewerBuilderDelegate(
+    final result = await AssetPickerViewer.pushToViewerWithDelegate<
+        File,
+        Directory,
+        FileAssetPickerViewerProvider,
+        FileAssetPickerViewerBuilderDelegate>(
+      context,
+      delegate: FileAssetPickerViewerBuilderDelegate(
         currentIndex: index ?? provider.selectedAssets.indexOf(currentAsset),
         previewAssets: provider.selectedAssets,
         provider: FileAssetPickerViewerProvider(provider.selectedAssets),
@@ -378,39 +385,11 @@ class FileAssetPickerBuilder
         selectorProvider: provider,
       ),
     );
-    final List<File>? result =
-        await Navigator.maybeOf(context)?.push<List<File>?>(
-      AssetPickerViewerPageRoute(builder: (context) => viewer),
-    );
     if (result != null) {
       Navigator.maybeOf(context)?.maybePop(result);
     }
   }
 
-  Future<List<File>?> pushToPicker(
-    BuildContext context, {
-    required int index,
-    required List<File> previewAssets,
-    List<File>? selectedAssets,
-    FileAssetPickerProvider? selectorProvider,
-  }) async {
-    final Widget viewer = AssetPickerViewer<File, Directory>(
-      builder: FileAssetPickerViewerBuilderDelegate(
-        currentIndex: index,
-        previewAssets: previewAssets,
-        provider: selectedAssets != null
-            ? FileAssetPickerViewerProvider(selectedAssets)
-            : null,
-        themeData: AssetPicker.themeData(themeColor),
-        selectedAssets: selectedAssets,
-        selectorProvider: selectorProvider,
-      ),
-    );
-    return await Navigator.maybeOf(context)?.push<List<File>?>(
-      AssetPickerViewerPageRoute(builder: (context) => viewer),
-    );
-  }
-
   @override
   void selectAsset(BuildContext context, File asset, int index, bool selected) {
     if (selected) {
@@ -975,23 +954,12 @@ class FileAssetPickerBuilder
 
   @override
   Widget previewButton(BuildContext context) {
-    return Selector<FileAssetPickerProvider, bool>(
-      selector: (_, FileAssetPickerProvider p) => p.isSelectedNotEmpty,
-      builder: (_, bool isSelectedNotEmpty, __) {
+    return Consumer<FileAssetPickerProvider>(
+      builder: (_, p, __) {
+        final isSelectedNotEmpty = p.isSelectedNotEmpty;
         return GestureDetector(
           onTap: isSelectedNotEmpty
-              ? () async {
-                  final List<File>? result = await pushToPicker(
-                    context,
-                    index: 0,
-                    previewAssets: provider.selectedAssets,
-                    selectedAssets: provider.selectedAssets,
-                    selectorProvider: provider,
-                  );
-                  if (result != null) {
-                    Navigator.maybeOf(context)?.pop(result);
-                  }
-                }
+              ? () => viewAsset(context, null, p.selectedAssets.first)
               : null,
           child: Padding(
             padding: const EdgeInsets.symmetric(vertical: 12.0),
@@ -1099,15 +1067,8 @@ class FileAssetPickerBuilder
             selectedAssets.where((File f) => f.path == asset.path).isNotEmpty;
         return Positioned.fill(
           child: GestureDetector(
-            onTap: () async {
-              final List<File>? result = await pushToPicker(
-                context,
-                index: index,
-                previewAssets: provider.currentAssets,
-              );
-              if (result != null) {
-                Navigator.maybeOf(context)?.pop(result);
-              }
+            onTap: () {
+              viewAsset(context, index, asset);
             },
             child: AnimatedContainer(
               duration: switchingPathDuration,
@@ -1159,7 +1120,8 @@ class FileAssetPickerBuilder
   }
 }
 
-class FileAssetPickerViewerProvider extends AssetPickerViewerProvider<File> {
+final class FileAssetPickerViewerProvider
+    extends AssetPickerViewerProvider<File> {
   FileAssetPickerViewerProvider(List<File> super.assets);
 
   @override
@@ -1170,18 +1132,19 @@ class FileAssetPickerViewerProvider extends AssetPickerViewerProvider<File> {
   }
 }
 
-class FileAssetPickerViewerBuilderDelegate
-    extends AssetPickerViewerBuilderDelegate<File, Directory> {
+final class FileAssetPickerViewerBuilderDelegate
+    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 +286,7 @@ class _InstaAssetPickerState extends State<InstaAssetPicker> {
   }
 }
 
-class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
+final class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
   InstaAssetPickerBuilder({
     required super.provider,
     required super.initialPermission,
@@ -488,8 +488,8 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
           width: MediaQuery.sizeOf(context).width,
           height: previewHeight(context),
           child: Selector<DefaultAssetPickerProvider, List<AssetEntity>>(
-            selector: (_, DefaultAssetPickerProvider p) => p.selectedAssets,
-            builder: (_, List<AssetEntity> selected, __) {
+            selector: (_, p) => p.selectedAssets,
+            builder: (_, selected, __) {
               if (previewAsset == null && selected.isEmpty) {
                 return loadingIndicator(context);
               }
@@ -499,10 +499,13 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
               if (previewAsset != null) {
                 effectiveIndex = selected.indexOf(previewAsset);
               }
-              final List<AssetEntity> assets =
-                  selected.isEmpty ? <AssetEntity>[previewAsset!] : selected;
+              final assets = selected.isEmpty ? [previewAsset!] : selected;
 
-              return AssetPickerViewer<AssetEntity, AssetPathEntity>(
+              return AssetPickerViewer<
+                  AssetEntity,
+                  AssetPathEntity,
+                  AssetPickerViewerProvider<AssetEntity>,
+                  InstaAssetPickerViewerBuilder>(
                 builder: InstaAssetPickerViewerBuilder(
                   currentIndex: effectiveIndex == -1 ? 0 : effectiveIndex,
                   previewAssets: assets,
@@ -645,7 +648,7 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
   Widget _buildListAlbums(BuildContext context) {
     appBarPreferredSize ??= appBar(context).preferredSize;
     return Consumer<DefaultAssetPickerProvider>(
-      builder: (BuildContext context, DefaultAssetPickerProvider provider, __) {
+      builder: (context, provider, __) {
         if (isAppleOS(context)) {
           return pathEntityListWidget(context);
         }
@@ -673,7 +676,7 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
   Widget _buildGrid(BuildContext context) {
     appBarPreferredSize ??= appBar(context).preferredSize;
     return Consumer<DefaultAssetPickerProvider>(
-      builder: (BuildContext context, DefaultAssetPickerProvider p, __) {
+      builder: (context, p, __) {
         final bool shouldDisplayAssets =
             p.hasAssetsToDisplay || shouldBuildSpecialItem;
         _initializePreviewAsset(p, shouldDisplayAssets);
@@ -767,7 +770,7 @@ class InstaAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
       const SizedBox.shrink();
 }
 
-class InstaAssetPickerViewerBuilder
+final class InstaAssetPickerViewerBuilder
     extends DefaultAssetPickerViewerBuilderDelegate {
   InstaAssetPickerViewerBuilder({
     required super.currentIndex,

example/lib/customs/pickers/multi_tabs_assets_picker.dart

@@ -260,7 +260,8 @@ class _MultiTabAssetPickerState extends State<MultiTabAssetPicker> {
   }
 }
 
-class MultiTabAssetPickerBuilder extends DefaultAssetPickerBuilderDelegate {
+final class MultiTabAssetPickerBuilder
+    extends DefaultAssetPickerBuilderDelegate {
   MultiTabAssetPickerBuilder({
     required super.provider,
     required this.videosProvider,
@@ -279,7 +280,10 @@ 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);
   }