Add a hook to create a collage

lib/generated/intl/messages_en.dart

@@ -427,6 +427,7 @@ class MessageLookup extends MessageLookupByLibrary {
         "createAccount": MessageLookupByLibrary.simpleMessage("Create account"),
         "createAlbumActionHint": MessageLookupByLibrary.simpleMessage(
             "Long press to select photos and click + to create an album"),
+        "createCollage": MessageLookupByLibrary.simpleMessage("Create collage"),
         "createNewAccount":
             MessageLookupByLibrary.simpleMessage("Create new account"),
         "createOrSelectAlbum":

lib/generated/l10n.dart

@@ -4855,6 +4855,16 @@ class S {
     );
   }
 
+  /// `Create collage`
+  String get createCollage {
+    return Intl.message(
+      'Create collage',
+      name: 'createCollage',
+      desc: '',
+      args: [],
+    );
+  }
+
   /// `Add to ente`
   String get addToEnte {
     return Intl.message(

lib/l10n/intl_en.arb

@@ -687,6 +687,7 @@
   "favorite": "Favorite",
   "removeFromFavorite": "Remove from favorite",
   "shareLink": "Share link",
+  "createCollage": "Create collage",
   "addToEnte": "Add to ente",
   "addToAlbum": "Add to album",
   "delete": "Delete",

lib/ui/viewer/actions/file_selection_actions_widget.dart

@@ -6,6 +6,7 @@ import "package:photos/generated/l10n.dart";
 import 'package:photos/models/collection.dart';
 import 'package:photos/models/device_collection.dart';
 import 'package:photos/models/file.dart';
+import "package:photos/models/file_type.dart";
 import 'package:photos/models/files_split.dart';
 import 'package:photos/models/gallery_type.dart';
 import "package:photos/models/metadata/common_keys.dart";
@@ -33,6 +34,9 @@ class FileSelectionActionWidget extends StatefulWidget {
   final DeviceCollection? deviceCollection;
   final SelectedFiles selectedFiles;
 
+  static const int collageItemsMin = 2;
+  static const int collageItemsMax = 5;
+
   const FileSelectionActionWidget(
     this.type,
     this.selectedFiles, {
@@ -135,6 +139,28 @@ class _FileSelectionActionWidgetState extends State<FileSelectionActionWidget> {
       }
     }
 
+    bool hasVideoFile = false;
+    for (final file in widget.selectedFiles.files) {
+      if (file.fileType == FileType.video) {
+        hasVideoFile = true;
+      }
+    }
+
+    if (!hasVideoFile &&
+        widget.selectedFiles.files.length >=
+            FileSelectionActionWidget.collageItemsMin &&
+        widget.selectedFiles.files.length <=
+            FileSelectionActionWidget.collageItemsMax) {
+      firstList.add(
+        BlurMenuItemWidget(
+          leadingIcon: Icons.grid_view_outlined,
+          labelText: S.of(context).createCollage,
+          menuItemColor: colorScheme.fillFaint,
+          onTap: () {},
+        ),
+      );
+    }
+
     final showUploadIcon = widget.type == GalleryType.localFolder &&
         split.ownedByCurrentUser.isEmpty;
     if (widget.type.showAddToAlbum()) {