🐛 Fix the experience with shouldRevertGrid (#552)

Address
#546 (comment).

Author: AlexV525

CHANGELOG.md

@@ -16,9 +16,10 @@ that can be found in the LICENSE file. -->
 
 ### Fixes
 
-- Fix previewing selected assets behavior.
+- Fix previewing selected assets' behavior.
 - Use `PermissionRequestOption` as much as possible.
 - Raise more errors for non-synced paths.
+- Fix the experience with `shouldRevertGrid`.
 
 ## 9.0.0-dev.2
 

lib/src/constants/typedefs.dart

@@ -8,7 +8,7 @@ import 'package:flutter/widgets.dart';
 import 'package:photo_manager/photo_manager.dart' show PermissionState;
 import 'package:provider/provider.dart';
 
-/// {@nodoc}
+/// Mirroring [ChangeNotifierProvider].
 typedef CNP<T extends ChangeNotifier?> = ChangeNotifierProvider<T>;
 
 /// {@template wechat_assets_picker.LoadingIndicatorBuilder}

lib/src/delegates/asset_picker_builder_delegate.dart

@@ -883,7 +883,8 @@ class DefaultAssetPickerBuilderDelegate
             provider.selectedAssets.isNotEmpty)) {
       return;
     }
-    final List<AssetEntity> current;
+    final revert = effectiveShouldRevertGrid(context);
+    List<AssetEntity> current;
     final List<AssetEntity>? selected;
     final int effectiveIndex;
     if (isWeChatMoment) {
@@ -905,7 +906,10 @@ class DefaultAssetPickerBuilderDelegate
     } else {
       current = provider.currentAssets;
       selected = provider.selectedAssets;
-      effectiveIndex = index;
+      effectiveIndex = revert ? current.length - index - 1 : index;
+    }
+    if (revert && index == null) {
+      current = current.reversed.toList(growable: false);
     }
     final List<AssetEntity>? result = await AssetPickerViewer.pushToViewer(
       context,
@@ -918,7 +922,7 @@ class DefaultAssetPickerBuilderDelegate
       selectorProvider: provider,
       specialPickerType: specialPickerType,
       maxAssets: provider.maxAssets,
-      shouldReversePreview: isAppleOS(context),
+      shouldReversePreview: revert,
     );
     if (result != null) {
       Navigator.of(context).maybePop(result);

lib/src/delegates/asset_picker_viewer_builder_delegate.dart

@@ -410,7 +410,9 @@ class DefaultAssetPickerViewerBuilderDelegate
 
   @override
   Widget assetPageBuilder(BuildContext context, int index) {
-    final AssetEntity asset = previewAssets.elementAt(index);
+    final AssetEntity asset = previewAssets.elementAt(
+      shouldReversePreview ? previewAssets.length - index - 1 : index,
+    );
     final Widget builder = switch (asset.type) {
       AssetType.audio => AudioPageBuilder(asset: asset),
       AssetType.image => ImagePageBuilder(
@@ -634,7 +636,10 @@ class DefaultAssetPickerViewerBuilderDelegate
           stream: pageStreamController.stream,
           builder: (_, AsyncSnapshot<int> snapshot) {
             final AssetEntity asset = selectedAssets!.elementAt(index);
-            final bool isViewing = previewAssets[snapshot.data!] == asset;
+            final viewingIndex = shouldReversePreview
+                ? previewAssets.length - snapshot.data! - 1
+                : snapshot.data!;
+            final bool isViewing = previewAssets[viewingIndex] == asset;
             final Widget item = switch (asset.type) {
               AssetType.image => _imagePreviewItem(asset),
               AssetType.video => _videoPreviewItem(asset),
@@ -930,7 +935,6 @@ class DefaultAssetPickerViewerBuilderDelegate
         controller: pageController,
         itemCount: previewAssets.length,
         itemBuilder: assetPageBuilder,
-        reverse: shouldReversePreview,
         onPageChanged: (int index) {
           currentIndex = index;
           pageStreamController.add(index);