Add hero animation when opening image

app/lib/flutter_util.dart

@@ -0,0 +1,21 @@
+import 'package:flutter/material.dart';
+import 'package:nc_photos/entity/file.dart';
+
+class CustomizableMaterialPageRoute extends MaterialPageRoute {
+  CustomizableMaterialPageRoute({
+    required super.builder,
+    super.settings,
+    super.maintainState,
+    super.fullscreenDialog,
+    required this.transitionDuration,
+    required this.reverseTransitionDuration,
+  });
+
+  @override
+  final Duration transitionDuration;
+
+  @override
+  final Duration reverseTransitionDuration;
+}
+
+String getImageHeroTag(File file) => "imageHero(${file.path})";

app/lib/k.dart

@@ -18,7 +18,9 @@ const animationDurationNormal = Duration(milliseconds: 250);
 const animationDurationLong = Duration(milliseconds: 500);
 
 /// Duration for tab transition animation
-const animationDurationTabTransition = Duration(milliseconds: 400);
+const animationDurationTabTransition = Duration(milliseconds: 350);
+
+const heroDurationNormal = Duration(milliseconds: 450);
 
 /// Size of the photo/video thumbnails
 ///

app/lib/widget/album_browser.dart

@@ -17,6 +17,7 @@ import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/entity/file_util.dart' as file_util;
 import 'package:nc_photos/event/event.dart';
 import 'package:nc_photos/exception_util.dart' as exception_util;
+import 'package:nc_photos/flutter_util.dart' as flutter_util;
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/list_extension.dart';
 import 'package:nc_photos/object_extension.dart';
@@ -974,6 +975,7 @@ class _ImageListItem extends _FileListItem {
         account: account,
         previewUrl: previewUrl,
         isGif: file.contentType == "image/gif",
+        heroKey: flutter_util.getImageHeroTag(file),
       );
 
   final Account account;

app/lib/widget/dynamic_album_browser.dart

@@ -18,6 +18,7 @@ import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/entity/file_util.dart' as file_util;
 import 'package:nc_photos/event/event.dart';
 import 'package:nc_photos/exception_util.dart' as exception_util;
+import 'package:nc_photos/flutter_util.dart' as flutter_util;
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/object_extension.dart';
 import 'package:nc_photos/or_null.dart';
@@ -716,6 +717,7 @@ class _ImageListItem extends _FileListItem {
         account: account,
         previewUrl: previewUrl,
         isGif: file.contentType == "image/gif",
+        heroKey: flutter_util.getImageHeroTag(file),
       );
 
   final Account account;

app/lib/widget/image_viewer.dart

@@ -8,6 +8,7 @@ import 'package:nc_photos/api/api_util.dart' as api_util;
 import 'package:nc_photos/cache_manager_util.dart';
 import 'package:nc_photos/entity/file.dart' as app;
 import 'package:nc_photos/entity/local_file.dart';
+import 'package:nc_photos/flutter_util.dart' as flutter_util;
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/mobile/android/content_uri_image_provider.dart';
 import 'package:nc_photos/widget/cached_network_image_mod.dart' as mod;
@@ -115,23 +116,26 @@ class _RemoteImageViewerState extends State<RemoteImageViewer> {
         onHeightChanged: widget.onHeightChanged,
         onZoomStarted: widget.onZoomStarted,
         onZoomEnded: widget.onZoomEnded,
-        child: mod.CachedNetworkImage(
-          cacheManager: LargeImageCacheManager.inst,
-          imageUrl: _getImageUrl(widget.account, widget.file),
-          httpHeaders: {
-            "Authorization": Api.getAuthorizationHeaderValue(widget.account),
-          },
-          fit: BoxFit.contain,
-          fadeInDuration: const Duration(),
-          filterQuality: FilterQuality.high,
-          imageRenderMethodForWeb: ImageRenderMethodForWeb.HttpGet,
-          imageBuilder: (context, child, imageProvider) {
-            WidgetsBinding.instance.addPostFrameCallback((_) {
-              _onItemLoaded();
-            });
-            const SizeChangedLayoutNotification().dispatch(context);
-            return child;
-          },
+        child: Hero(
+          tag: flutter_util.getImageHeroTag(widget.file),
+          child: mod.CachedNetworkImage(
+            cacheManager: LargeImageCacheManager.inst,
+            imageUrl: _getImageUrl(widget.account, widget.file),
+            httpHeaders: {
+              "Authorization": Api.getAuthorizationHeaderValue(widget.account),
+            },
+            fit: BoxFit.contain,
+            fadeInDuration: const Duration(),
+            filterQuality: FilterQuality.high,
+            imageRenderMethodForWeb: ImageRenderMethodForWeb.HttpGet,
+            imageBuilder: (context, child, imageProvider) {
+              WidgetsBinding.instance.addPostFrameCallback((_) {
+                _onItemLoaded();
+              });
+              const SizeChangedLayoutNotification().dispatch(context);
+              return child;
+            },
+          ),
         ),
       );
 

app/lib/widget/photo_list_item.dart

@@ -7,6 +7,7 @@ import 'package:nc_photos/account.dart';
 import 'package:nc_photos/api/api.dart';
 import 'package:nc_photos/app_localizations.dart';
 import 'package:nc_photos/cache_manager_util.dart';
+import 'package:nc_photos/flutter_util.dart'as flutter_util;
 import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/entity/local_file.dart';
 import 'package:nc_photos/k.dart' as k;
@@ -65,6 +66,7 @@ class PhotoListImageItem extends PhotoListFileItem {
         previewUrl: previewUrl,
         isGif: file.contentType == "image/gif",
         isFavorite: shouldShowFavoriteBadge && file.isFavorite == true,
+        heroKey: flutter_util.getImageHeroTag(file),
       );
 
   final Account account;
@@ -214,10 +216,45 @@ class PhotoListImage extends StatelessWidget {
     this.padding = const EdgeInsets.all(2),
     this.isGif = false,
     this.isFavorite = false,
+    this.heroKey,
   }) : super(key: key);
 
   @override
   build(BuildContext context) {
+    Widget buildPlaceholder() => Center(
+          child: Icon(
+            Icons.image_not_supported,
+            size: 64,
+            color: Colors.white.withOpacity(.8),
+          ),
+        );
+    Widget child;
+    if (previewUrl == null) {
+      child = buildPlaceholder();
+    } else {
+      child = CachedNetworkImage(
+        cacheManager: ThumbnailCacheManager.inst,
+        imageUrl: previewUrl!,
+        httpHeaders: {
+          "Authorization": Api.getAuthorizationHeaderValue(account),
+        },
+        fadeInDuration: const Duration(),
+        filterQuality: FilterQuality.high,
+        errorWidget: (context, url, error) {
+          // won't work on web because the image is downloaded by
+          // the cache manager instead
+          return buildPlaceholder();
+        },
+        imageRenderMethodForWeb: ImageRenderMethodForWeb.HttpGet,
+      );
+      if (heroKey != null) {
+        child = Hero(
+          tag: heroKey!,
+          child: child,
+        );
+      }
+    }
+
     return Padding(
       padding: padding,
       child: FittedBox(
@@ -229,37 +266,7 @@ class PhotoListImage extends StatelessWidget {
               // arbitrary size here
               constraints: BoxConstraints.tight(const Size(128, 128)),
               color: AppTheme.getListItemBackgroundColor(context),
-              child: previewUrl == null
-                  ? Center(
-                      child: Icon(
-                        Icons.image_not_supported,
-                        size: 64,
-                        color: Colors.white.withOpacity(.8),
-                      ),
-                    )
-                  : CachedNetworkImage(
-                      cacheManager: ThumbnailCacheManager.inst,
-                      imageUrl: previewUrl!,
-                      httpHeaders: {
-                        "Authorization":
-                            Api.getAuthorizationHeaderValue(account),
-                      },
-                      fadeInDuration: const Duration(),
-                      filterQuality: FilterQuality.high,
-                      errorWidget: (context, url, error) {
-                        // won't work on web because the image is downloaded by
-                        // the cache manager instead
-                        // where's the preview???
-                        return Center(
-                          child: Icon(
-                            Icons.image_not_supported,
-                            size: 64,
-                            color: Colors.white.withOpacity(.8),
-                          ),
-                        );
-                      },
-                      imageRenderMethodForWeb: ImageRenderMethodForWeb.HttpGet,
-                    ),
+              child: child,
             ),
             if (isGif)
               Container(
@@ -296,6 +303,8 @@ class PhotoListImage extends StatelessWidget {
   final bool isGif;
   final EdgeInsetsGeometry padding;
   final bool isFavorite;
+  // if not null, the image will be contained by a Hero widget
+  final String? heroKey;
 }
 
 class PhotoListVideo extends StatelessWidget {

app/lib/widget/smart_album_browser.dart

@@ -12,6 +12,7 @@ import 'package:nc_photos/entity/album/item.dart';
 import 'package:nc_photos/entity/album/provider.dart';
 import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/entity/file_util.dart' as file_util;
+import 'package:nc_photos/flutter_util.dart' as flutter_util;
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/object_extension.dart';
 import 'package:nc_photos/share_handler.dart';
@@ -385,6 +386,7 @@ class _ImageListItem extends _FileListItem {
         account: account,
         previewUrl: previewUrl,
         isGif: file.contentType == "image/gif",
+        heroKey: flutter_util.getImageHeroTag(file),
       );
 
   final Account account;

app/lib/widget/viewer.dart

@@ -14,6 +14,7 @@ import 'package:nc_photos/download_handler.dart';
 import 'package:nc_photos/entity/album.dart';
 import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/entity/file_util.dart' as file_util;
+import 'package:nc_photos/flutter_util.dart';
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/notified_action.dart';
 import 'package:nc_photos/platform/features.dart' as features;
@@ -52,8 +53,11 @@ class ViewerArguments {
 class Viewer extends StatefulWidget {
   static const routeName = "/viewer";
 
-  static Route buildRoute(ViewerArguments args) => MaterialPageRoute(
-        builder: (context) => Viewer.fromArgs(args),
+  static Route buildRoute(ViewerArguments args) =>
+      CustomizableMaterialPageRoute(
+        transitionDuration: k.heroDurationNormal,
+        reverseTransitionDuration: k.heroDurationNormal,
+        builder: (_) => Viewer.fromArgs(args),
       );
 
   const Viewer({