MESSENGER-3699 double tap for image attachments

Riot/Modules/Room/Attachements/MXKAttachmentsViewController.m

@@ -820,11 +820,18 @@
         // Note: tap gesture recognizer is required here because mxkImageView enables user interaction to allow image stretching.
         // [collectionView:didSelectItemAtIndexPath] is not triggered when mxkImageView is displayed.
         UITapGestureRecognizer *cellTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onCollectionViewCellTap:)];
-        [cellTapGesture setNumberOfTouchesRequired:1];
         [cellTapGesture setNumberOfTapsRequired:1];
         cell.tag = item;
         [cell addGestureRecognizer:cellTapGesture];
         
+        // BWI: allow changing the image zoom level by double tab
+        if ([BwiBuildSettings allowDoubleTapOnImageAttachmentsForZoom]) {
+            UITapGestureRecognizer *cellDoubleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onCollectionViewCellDoubleTap:)];
+            [cellDoubleTapGesture setNumberOfTapsRequired:2];
+            cell.tag = item;
+            [cell addGestureRecognizer:cellDoubleTapGesture];
+        }
+
         UILongPressGestureRecognizer *cellLongPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(onCollectionViewCellLongPress:)];
         [cell addGestureRecognizer:cellLongPressGesture];
     }
@@ -1172,6 +1179,43 @@
     }
 }
 
+- (void)onCollectionViewCellDoubleTap:(UIGestureRecognizer*)gestureRecognizer
+{
+    MXKMediaCollectionViewCell *selectedCell;
+    
+    UIView *view = gestureRecognizer.view;
+    if ([view isKindOfClass:[MXKMediaCollectionViewCell class]])
+    {
+        selectedCell = (MXKMediaCollectionViewCell*)view;
+    }
+    
+    // Notify the collection view delegate a cell has been selected.
+    if (selectedCell && selectedCell.tag < attachments.count)
+    {
+        NSInteger item = isBackPaginationInProgress ? selectedCell.tag + 1: selectedCell.tag;
+                
+        if (isBackPaginationInProgress)
+        {
+            if (item == 0)
+            {
+                return;
+            }
+            
+            item --;
+        }
+        
+        // Check whether the selected attachment is a video
+        if (item < attachments.count)
+        {
+            MXKAttachment *attachment = attachments[item];
+            if (attachment.type == MXKAttachmentTypeImage && attachment.contentURL)
+            {
+                [selectedCell.mxkImageView toggleZoomLevel];
+            }
+        }
+    }
+}
+
 - (void)onCollectionViewCellLongPress:(UIGestureRecognizer*)gestureRecognizer
 {
     MXKMediaCollectionViewCell *selectedCell;