Fixes a glitch when dismissing a GIF in the media attachment viewer (#6475)

Riot/Modules/MatrixKit/Animators/MXKAttachmentAnimator.h

@@ -32,6 +32,8 @@ typedef NS_ENUM(NSInteger, PhotoBrowserAnimationType) {
 
 @protocol MXKDestinationAttachmentAnimatorDelegate <NSObject>
 
+- (BOOL)prepareSubviewsForTransition:(BOOL)isStartInteraction;
+
 - (UIImageView *)finalImageView;
 
 @end

Riot/Modules/MatrixKit/Animators/MXKAttachmentInteractionController.m

@@ -111,7 +111,9 @@ - (void)handleGesture:(UIPanGestureRecognizer *)recognizer
 - (void)startInteractiveTransition:(id <UIViewControllerContextTransitioning>)transitionContext
 {
     self.transitionContext = transitionContext;
-
+
+    [self.destinationViewController prepareSubviewsForTransition:YES];
+
     UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
     UIImageView *destinationImageView = [self.destinationViewController finalImageView];
     destinationImageView.hidden = YES;
@@ -158,6 +160,8 @@ - (void)cancelInteractiveTransition {
 
             [self.transitionContext cancelInteractiveTransition];
             [self.transitionContext completeTransition:NO];
+
+            [self.destinationViewController prepareSubviewsForTransition:NO];
         }
     }];
 }

Riot/Modules/Room/Attachements/MXKAttachmentsViewController.m

@@ -701,7 +701,7 @@ - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cell
                     width = minSize;
                     height = minSize;
                 }
-                
+
                 WKWebView *animatedGifViewer = [[WKWebView alloc] initWithFrame:CGRectMake(0, 0, width, height)];
                 animatedGifViewer.center = cell.customView.center;
                 animatedGifViewer.opaque = NO;
@@ -1379,6 +1379,30 @@ - (void)documentInteractionControllerDidDismissOpenInMenu:(UIDocumentInteraction
     }
 }
 
+#pragma mark - MXKDestinationAttachmentAnimatorDelegate
+
+- (BOOL)prepareSubviewsForTransition:(BOOL)isStartInteraction
+{
+    MXKMediaCollectionViewCell *cell = (MXKMediaCollectionViewCell *)[self.attachmentsCollection.visibleCells firstObject];
+    MXKAttachment *attachment = attachments[currentVisibleItemIndex];
+    NSString *mimeType = attachment.contentInfo[@"mimetype"];
+
+    // Check attachment type for GIFs - this is required because of the extra WKWebView
+    if (attachment.type == MXKAttachmentTypeImage && attachment.contentURL && [mimeType isEqualToString:@"image/gif"])
+    {
+        UIView *customView = cell.customView;
+        for (UIView *v in customView.subviews)
+        {
+            if ([v isKindOfClass:[WKWebView class]])
+            {
+                v.hidden = isStartInteraction;
+                return YES;
+            }
+        }
+    }
+    return NO;
+}
+
 - (UIImageView *)finalImageView
 {
     MXKMediaCollectionViewCell *cell = (MXKMediaCollectionViewCell *)[self.attachmentsCollection.visibleCells firstObject];

changelog.d/6475.bugfix

@@ -0,0 +1 @@
+Media Attachments Viewer: Fixed an issue where dismissing GIFs would show the WebView playing the animation below the interaction transition animation.