Switch gallery to grid view

lib/screens/gallery_screen.dart

@@ -69,6 +69,31 @@ class GalleryScreen extends StatelessWidget {
       );
     }
 
+    return GridView.builder(
+        itemCount: images.length,
+        padding: EdgeInsets.all(5.0),
+        gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
+            maxCrossAxisExtent: thumbnailDimension),
+        itemBuilder: (context, index) {
+          final image = images[index];
+          return Padding(
+            padding: const EdgeInsets.all(2.0),
+            child: InkWell(
+              onTap: () {
+                Navigator.push(context, MaterialPageRoute(builder: (context) {
+                  return ImageViewerScreen(
+                      attachment: image.toMediaAttachment());
+                }));
+              },
+              child: CachedNetworkImage(
+                width: thumbnailDimension,
+                height: thumbnailDimension,
+                imageUrl: image.thumbnailUrl,
+              ),
+            ),
+          );
+        });
+
     return ListView.separated(
       itemBuilder: (context, index) {
         final image = images[index];