Additional feed performance improvements

lib/src/features/community/presentation/widgets/post_card_view_comfortable.dart

@@ -2,10 +2,8 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 import 'package:flutter_bloc/flutter_bloc.dart';
-import 'package:html/parser.dart';
-import 'package:markdown/markdown.dart' hide Text;
-import 'package:thunder/src/app/cubits/feed_ui_cubit/feed_ui_cubit.dart';
 
+import 'package:thunder/src/app/cubits/feed_ui_cubit/feed_ui_cubit.dart';
 import 'package:thunder/src/features/community/community.dart';
 import 'package:thunder/src/features/post/post.dart';
 import 'package:thunder/src/core/enums/media_type.dart';
@@ -204,7 +202,7 @@ class PostCardViewComfortable extends StatelessWidget {
             Padding(
               padding: const EdgeInsets.only(bottom: 6.0, left: 12.0, right: 12.0),
               child: ScalableText(
-                parse(markdownToHtml(textContent)).documentElement?.text.trim() ?? textContent,
+                post.textPreview ?? textContent,
                 maxLines: 4,
                 overflow: TextOverflow.ellipsis,
                 fontScale: contentFontSizeScale,

lib/src/features/feed/presentation/widgets/feed_post_card_list.dart

@@ -4,9 +4,9 @@ import 'package:flutter/material.dart';
 
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:flutter_staggered_grid_view/flutter_staggered_grid_view.dart';
-import 'package:thunder/src/features/post/post.dart';
 import 'package:visibility_detector/visibility_detector.dart';
 
+import 'package:thunder/src/features/post/post.dart';
 import 'package:thunder/src/features/account/account.dart';
 import 'package:thunder/src/core/enums/enums.dart';
 import 'package:thunder/src/features/community/community.dart';
@@ -57,6 +57,9 @@ class _FeedPostCardListState extends State<FeedPostCardList> {
   /// This is used to calculate the read status of posts in the range [0, lastTappedIndex]
   int lastTappedIndex = -1;
 
+  /// The index of the last processed post for read status.
+  int lastProcessedIndex = -1;
+
   /// Whether the user is scrolling down or not. The logic for determining read posts will
   /// only be applied when the user is scrolling down
   bool isScrollingDown = false;
@@ -134,7 +137,10 @@ class _FeedPostCardListState extends State<FeedPostCardList> {
 
             debounceTimer = Timer(const Duration(milliseconds: 500), () {
               // TODO: Improve logic here so that we don't have to iterate through all posts if possible.
-              for (int i = index; i >= 0; i--) {
+              int startIndex = index;
+              int endIndex = lastProcessedIndex > 0 ? lastProcessedIndex : 0;
+
+              for (int i = startIndex; i >= endIndex; i--) {
                 final post = widget.posts[i];
 
                 // If we already checked this post's read status, or we already marked it as read, skip it
@@ -145,6 +151,9 @@ class _FeedPostCardListState extends State<FeedPostCardList> {
                 readPostIds.add(post.id);
               }
 
+              // Update the last processed index
+              if (index > lastProcessedIndex) lastProcessedIndex = index;
+
               if (markReadPostIds.isNotEmpty) {
                 context.read<FeedBloc>().add(FeedItemActionedEvent(postIds: [...markReadPostIds], postAction: PostAction.multiRead, value: true));
                 readPostIds.addAll(markReadPostIds); // Add all post ids that were queued to prevent them from being queued again

lib/src/features/post/data/models/thunder_post.dart

@@ -66,6 +66,11 @@ class ThunderPost extends Equatable {
   /// The post's alternate text
   final String? altText;
 
+  /// The post's text preview.
+  ///
+  /// This field is not returned by the API, but is computed locally during post parsing.
+  final String? textPreview;
+
   /// The post's creator
   final ThunderUser? creator;
 
@@ -163,6 +168,7 @@ class ThunderPost extends Equatable {
     this.myVote,
     this.unreadComments,
     this.media = const [],
+    this.textPreview,
   });
 
   @override
@@ -206,6 +212,7 @@ class ThunderPost extends Equatable {
         myVote,
         unreadComments,
         media,
+        textPreview,
       ];
 
   ThunderPost copyWith({
@@ -248,6 +255,7 @@ class ThunderPost extends Equatable {
     int? myVote,
     int? unreadComments,
     List<Media>? media,
+    String? textPreview,
   }) {
     return ThunderPost(
       id: id ?? this.id,
@@ -289,6 +297,7 @@ class ThunderPost extends Equatable {
       myVote: myVote ?? this.myVote,
       unreadComments: unreadComments ?? this.unreadComments,
       media: media ?? this.media,
+      textPreview: textPreview ?? this.textPreview,
     );
   }
 

lib/src/features/post/presentation/utils/post.dart

@@ -1,6 +1,8 @@
 import 'package:flutter/material.dart';
 
 import 'package:html_unescape/html_unescape_small.dart';
+import 'package:html/parser.dart';
+import 'package:markdown/markdown.dart' hide Text;
 
 import 'package:thunder/src/features/account/account.dart';
 import 'package:thunder/src/core/enums/local_settings.dart';
@@ -12,6 +14,8 @@ import 'package:thunder/src/features/search/search.dart';
 import 'package:thunder/src/shared/utils/media/image.dart';
 import 'package:thunder/src/shared/utils/media/video.dart';
 
+final _htmlUnescape = HtmlUnescape();
+
 // Optimistically updates a post. This changes the value of the post locally, without sending the network request
 ThunderPost optimisticallyVotePost(ThunderPost post, int voteType) {
   int newScore = post.score!;
@@ -114,8 +118,13 @@ Future<List<ThunderPost>> parsePosts(List<ThunderPost> posts, {String? resolutio
 ///
 /// This includes unescaping the title and parsing any associated media.
 Future<ThunderPost> parsePost(ThunderPost post, bool fetchImageDimensions, bool edgeToEdgeImages, bool tabletMode) async {
-  final html = HtmlUnescape();
-  final title = html.convert(post.name);
+  final title = _htmlUnescape.convert(post.name);
+
+  // Compute text preview
+  String? textPreview;
+  if (post.body != null && post.body!.isNotEmpty) {
+    textPreview = parse(markdownToHtml(post.body!)).documentElement?.text.trim() ?? post.body;
+  }
 
   List<Media> mediaList = [];
 
@@ -191,5 +200,5 @@ Future<ThunderPost> parsePost(ThunderPost post, bool fetchImageDimensions, bool
   media.height = scaledSize?.height;
   mediaList.add(media);
 
-  return post.copyWith(media: mediaList, name: title);
+  return post.copyWith(media: mediaList, name: title, textPreview: textPreview);
 }

lib/src/shared/utils/media/image.dart

@@ -4,13 +4,14 @@ import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
-
 import 'package:flutter/services.dart';
+
 import 'package:flutter_avif/flutter_avif.dart';
 import 'package:flutter_cache_manager/flutter_cache_manager.dart';
 import 'package:http/http.dart' as http;
 import 'package:image/image.dart' as img;
 import 'package:image_picker/image_picker.dart';
+import 'package:image_dimension_parser/image_dimension_parser.dart';
 
 import 'package:thunder/src/core/cache/image_dimension_cache.dart';
 import 'package:thunder/src/shared/images/image_viewer.dart';
@@ -114,6 +115,25 @@ bool _isAvifImage(String path) {
   return path.toLowerCase().endsWith('.avif');
 }
 
+/// Fetches the image dimensions from the given URL using partial content fetch
+Future<List<int>> processImageDimensions(String imageUrl) async {
+  try {
+    final response = await http.get(
+      Uri.parse(imageUrl),
+      headers: {'Range': 'bytes=0-10240'}, // 10KB
+    );
+
+    if (response.statusCode == 206 || response.statusCode == 200) {
+      final sizeResult = ImageDimensionParser().parse(response.bodyBytes);
+      return [sizeResult.width, sizeResult.height];
+    }
+  } catch (e) {
+    debugPrint('Failed to fetch dimensions in isolate: $e');
+  }
+
+  return [];
+}
+
 /// Retrieves the size of the given image given its bytes.
 /// Uses the `image` package which does not support AVIF format. For AVIF images, use [processAvifImage] instead.
 Future<Size> processImage(String filename) async {
@@ -159,13 +179,27 @@ Future<Size> retrieveImageDimensions({String? imageUrl, Uint8List? imageBytes})
     Uint8List? data = imageBytes;
 
     if (data == null && imageUrl != null) {
-      final file = await DefaultCacheManager().getSingleFile(imageUrl);
+      // Try to get size using partial content fetch
+      try {
+        final dimensions = await compute(processImageDimensions, imageUrl);
+
+        if (dimensions.isNotEmpty) {
+          size = Size(dimensions[0].toDouble(), dimensions[1].toDouble());
+          debugPrint('Retrieved image dimensions using partial content fetch: ${dimensions[0]}x${dimensions[1]}');
+        }
+      } catch (e) {
+        // Fallback to full download if partial fetch fails
+        debugPrint('Failed to retrieve image dimensions using partial content fetch: $e');
+      }
+
+      if (size == null) {
+        final file = await DefaultCacheManager().getSingleFile(imageUrl);
 
-      if (_isAvifImage(imageUrl) || _isAvifImage(file.path)) {
-        size = await processAvifImage(file.path);
-      } else {
-        // Other formats can be processed in a background isolate using the `image` package.
-        size = await compute(processImage, file.path);
+        if (_isAvifImage(imageUrl)) {
+          size = await processAvifImage(file.path);
+        } else {
+          size = await compute(processImage, file.path);
+        }
       }
     }
 

pubspec.lock

@@ -981,6 +981,15 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.7.1"
+  image_dimension_parser:
+    dependency: "direct main"
+    description:
+      path: "."
+      ref: d9bfec9dfe6a53b2d032129ce56311ec02796a29
+      resolved-ref: d9bfec9dfe6a53b2d032129ce56311ec02796a29
+      url: "https://github.com/thunder-app/image-dimension-parser.git"
+    source: git
+    version: "1.0.0"
   image_picker:
     dependency: "direct main"
     description:
@@ -2053,5 +2062,5 @@ packages:
     source: hosted
     version: "3.1.2"
 sdks:
-  dart: ">=3.10.0 <4.0.0"
+  dart: ">=3.10.4 <4.0.0"
   flutter: ">=3.38.1"

pubspec.yaml

@@ -18,6 +18,10 @@ dependencies:
     git:
       url: https://github.com/thunder-app/markdown-editor.git
       ref: 34db147d5964b2e84f5a7e8edff4a5ce6b649ec8
+  image_dimension_parser:
+    git:
+      url: https://github.com/thunder-app/image-dimension-parser.git
+      ref: d9bfec9dfe6a53b2d032129ce56311ec02796a29
   l10n_esperanto: ^2.0.14
   android_intent_plus: ^6.0.0
   app_links: ^7.0.0