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/details/shared_items_view.dart

@@ -10,14 +10,16 @@ import '../../../../api/marianumcloud/talk/get_shared_items/get_shared_items_res
 import '../../../../api/marianumcloud/talk/room/get_room_response.dart';
 import '../../../../extensions/date_time.dart';
 import '../../../../model/endpoint_data.dart';
+import '../../../../routing/app_routes.dart';
 import '../../../../session/session_manager.dart';
 import '../../../../share_intent/remote_file_ref.dart';
 import '../../../../utils/downloads/download_job.dart';
 import '../../../../widget/app_progress_indicator.dart';
 import '../../../../widget/demo_restricted.dart';
 import '../../../../widget/downloads/download_trigger.dart';
+import '../data/talk_gallery_source.dart';
 
-const int _sharedItemsPageSize = 20;
+const int sharedItemsPageSize = 20;
 
 /// The non-media shared-item categories Talk exposes, in tab order. `media` is
 /// handled separately (split into Bilder/Videos). `location`/`deckcard` are rich
@@ -64,7 +66,7 @@ SharedItemsPage buildSharedItemsPage(
 ) {
   final lastGiven = response.lastGivenMessageId;
   final hasMore =
-      response.items.length >= _sharedItemsPageSize &&
+      response.items.length >= sharedItemsPageSize &&
       lastGiven != null &&
       lastGiven != previousMessageId;
   return SharedItemsPage(
@@ -79,7 +81,7 @@ SharedItemsPage buildSharedItemsPage(
 /// its `X-Chat-Last-Given` header. [hasMore] is a heuristic — a full page from
 /// the overview means there are probably older items to fetch on scroll.
 SharedItemsPage _seedFromOverview(List<GetChatResponseObject> rawItems) {
-  final hasMore = rawItems.length >= _sharedItemsPageSize;
+  final hasMore = rawItems.length >= sharedItemsPageSize;
   final oldestId = rawItems.isEmpty
       ? null
       : rawItems.map((item) => item.id).reduce((a, b) => a < b ? a : b);
@@ -106,7 +108,7 @@ class SharedItemsView extends StatefulWidget {
   /// screen, so opening this view needs no round-trip.
   static Future<GetSharedItemsOverviewResponse> prefetchOverview(
     String token,
-  ) => GetSharedItemsOverview(token, limit: _sharedItemsPageSize).run();
+  ) => GetSharedItemsOverview(token, limit: sharedItemsPageSize).run();
 
   @override
   State<SharedItemsView> createState() => _SharedItemsViewState();
@@ -362,7 +364,7 @@ class _SharedItemsTabState extends State<_SharedItemsTab>
       final response = await GetSharedItems(
         widget.token,
         objectType: widget.objectType,
-        limit: _sharedItemsPageSize,
+        limit: sharedItemsPageSize,
         lastKnownMessageId: _lastKnownMessageId,
       ).run();
       if (!mounted) return;
@@ -445,6 +447,7 @@ class _SharedItemsTabState extends State<_SharedItemsTab>
                 ),
                 delegate: SliverChildBuilderDelegate(
                   (context, index) => _SharedItemTile(
+                    token: widget.token,
                     item: _items[index],
                     layout: _SharedItemsLayout.grid,
                   ),
@@ -456,6 +459,7 @@ class _SharedItemsTabState extends State<_SharedItemsTab>
             SliverList(
               delegate: SliverChildBuilderDelegate(
                 (context, index) => _SharedItemTile(
+                  token: widget.token,
                   item: _items[index],
                   layout: _SharedItemsLayout.list,
                 ),
@@ -470,10 +474,15 @@ class _SharedItemsTabState extends State<_SharedItemsTab>
 }
 
 class _SharedItemTile extends StatefulWidget {
+  final String token;
   final GetChatResponseObject item;
   final _SharedItemsLayout layout;
 
-  const _SharedItemTile({required this.item, required this.layout});
+  const _SharedItemTile({
+    required this.token,
+    required this.item,
+    required this.layout,
+  });
 
   @override
   State<_SharedItemTile> createState() => _SharedItemTileState();
@@ -502,12 +511,18 @@ class _SharedItemTileState extends State<_SharedItemTile>
     if (guardDemoAction(context)) return;
     if (isDownloading) {
       confirmCancelDownload();
-    } else {
-      startDownload(
-        name: _file.name,
-        remoteFile: RemoteFileRef.fromTalk(_file),
-      );
+      return;
     }
+    final galleryItem = galleryItemFromTalk(widget.item);
+    if (galleryItem != null) {
+      AppRoutes.openMediaGallery(
+        context,
+        source: TalkGallerySource(token: widget.token, initial: galleryItem),
+        initialKey: galleryItem.key,
+      );
+      return;
+    }
+    startDownload(name: _file.name, remoteFile: RemoteFileRef.fromTalk(_file));
   }
 
   String get _previewUrl =>