added a swipeable media gallery for chat and folder images and videos with server previews, on-demand originals and zoom, and marked document previews in chat so they no longer pass for photos

lib/view/pages/talk/data/chat_message.dart

@@ -1,12 +1,10 @@
-import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 
 import '../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
 import '../../../../api/marianumcloud/talk/chat/rich_object_string_processor.dart';
-import '../../../../model/endpoint_data.dart';
-import '../../../../session/session_manager.dart';
 import '../../../../utils/emoji_detection.dart';
 import '../../../../utils/url_opener.dart';
+import '../widgets/chat_file_attachment.dart';
 import '../widgets/highlighted_linkify.dart';
 import '../widgets/message_markdown.dart';
 
@@ -78,36 +76,7 @@ class ChatMessage {
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: [
-          CachedNetworkImage(
-            errorWidget: (context, url, error) => Row(
-              mainAxisSize: MainAxisSize.min,
-              crossAxisAlignment: CrossAxisAlignment.center,
-              children: [
-                const Icon(Icons.file_open_outlined, size: 35),
-                const SizedBox(width: 10),
-                Flexible(
-                  child: Text(
-                    file.name,
-                    maxLines: 2,
-                    overflow: TextOverflow.ellipsis,
-                    style: const TextStyle(fontWeight: FontWeight.bold),
-                  ),
-                ),
-                const SizedBox(width: 10),
-              ],
-            ),
-            alignment: Alignment.center,
-            placeholder: (context, url) => const Padding(
-              padding: EdgeInsets.all(15),
-              child: SizedBox(width: 50, child: LinearProgressIndicator()),
-            ),
-            fadeInDuration: Duration.zero,
-            fadeOutDuration: Duration.zero,
-            errorListener: (value) {},
-            httpHeaders: SessionManager().requireNextcloud().authHeaders,
-            imageUrl:
-                '${EndpointData().nextcloud().origin()}/index.php/core/preview?fileId=${file.id}&x=130&y=-1&a=1',
-          ),
+          ChatFileAttachment(file: file),
           if (originalMessage != '{file}') ...[
             SizedBox(height: 5),
             contentWidget,

lib/view/pages/talk/data/talk_gallery_source.dart

@@ -0,0 +1,128 @@
+import '../../../../api/marianumcloud/talk/chat/get_chat_response.dart';
+import '../../../../api/marianumcloud/talk/get_shared_items/get_shared_items.dart';
+import '../../../../extensions/date_time.dart';
+import '../../../../session/session_manager.dart';
+import '../../../../share_intent/remote_file_ref.dart';
+import '../../../../widget/media_gallery/gallery_item.dart';
+import '../../../../widget/media_gallery/gallery_source.dart';
+import '../details/shared_items_view.dart';
+
+GalleryItem? galleryItemFromTalk(GetChatResponseObject message) {
+  final file = message.messageParameters?['file'];
+  if (file == null || file.path == null) return null;
+  final kind = galleryMediaKindOf(file.name, mimeType: file.mimetype);
+  if (kind == null) return null;
+  return GalleryItem(
+    file: RemoteFileRef.fromTalk(file),
+    kind: kind,
+    messageId: message.id,
+    subtitle:
+        '${message.actorDisplayName} · ${message.sentAt.formatDateTime()}',
+  );
+}
+
+/// All images and videos of a chat, via Talk's shared-items `media` stream.
+/// Opens on the tapped message and fills in around it in the background.
+class TalkGallerySource extends GallerySource {
+  /// The share endpoint only pages backwards from the newest item, so reaching
+  /// an old tapped image means walking down to it; give up beyond this.
+  static const _maxCatchUpPages = 25;
+
+  final String token;
+  final GalleryItem initial;
+  final int _epoch = SessionManager().sessionEpoch;
+
+  List<GalleryItem> _items;
+  int? _cursor;
+  bool _hasOlder = false;
+  bool _loading = false;
+  bool _disposed = false;
+
+  TalkGallerySource({required this.token, required this.initial})
+    : _items = [initial] {
+    _catchUp();
+  }
+
+  @override
+  List<GalleryItem> get items => _items;
+
+  @override
+  bool get hasOlder => _hasOlder && !_loading;
+
+  bool get _stale => _disposed || !SessionManager().isCurrentSession(_epoch);
+
+  Future<SharedItemsPage> _fetch(int? cursor) async => buildSharedItemsPage(
+    await GetSharedItems(
+      token,
+      objectType: 'media',
+      limit: sharedItemsPageSize,
+      lastKnownMessageId: cursor,
+    ).run(),
+    cursor,
+  );
+
+  Iterable<GalleryItem> _toItems(SharedItemsPage page) =>
+      page.items.map(galleryItemFromTalk).nonNulls;
+
+  Future<void> _catchUp() async {
+    final initialId = initial.messageId!;
+    _loading = true;
+    try {
+      final collected = <GalleryItem>[];
+      int? cursor;
+      var hasMore = true;
+      var reached = false;
+      for (var pages = 0; hasMore && pages < _maxCatchUpPages; pages++) {
+        final page = await _fetch(cursor);
+        if (_stale) return;
+        collected.addAll(_toItems(page));
+        cursor = page.lastKnownMessageId;
+        hasMore = page.hasMore;
+        if (page.items.any((item) => item.id <= initialId)) {
+          reached = true;
+          break;
+        }
+      }
+      if (reached || !hasMore) {
+        _items = mergeGalleryItems(_items, collected);
+        _cursor = cursor;
+        _hasOlder = hasMore;
+      } else {
+        // Too far down: skip the newer media and only page older ones.
+        _cursor = initialId;
+        _hasOlder = true;
+      }
+    } on Object {
+      if (_stale) return;
+      _cursor = initialId;
+      _hasOlder = true;
+    } finally {
+      _loading = false;
+    }
+    notifyListeners();
+  }
+
+  @override
+  Future<void> loadOlder() async {
+    if (!hasOlder) return;
+    _loading = true;
+    try {
+      final page = await _fetch(_cursor);
+      if (_stale) return;
+      _items = mergeGalleryItems(_items, _toItems(page));
+      _cursor = page.lastKnownMessageId;
+      _hasOlder = page.hasMore;
+    } on Object {
+      // Retried on the next page change.
+    } finally {
+      _loading = false;
+    }
+    if (!_stale) notifyListeners();
+  }
+
+  @override
+  void dispose() {
+    _disposed = true;
+    super.dispose();
+  }
+}