Changeset 210041 in webkit

Timestamp:

Dec 20, 2016, 3:32:28 PM (8 years ago)

Author:

Simon Fraser

Message:

[iOS WK2] Switching or closing a tab leads to all-white tab content if the status bar is double height
​https://bugs.webkit.org/show_bug.cgi?id=166286
rdar://problem/29593525

Reviewed by Tim Horton.

A double-height status bar triggers view resize while snapshotting in the background,
which also triggers calls to _endAnimatedResize on tab resume. However, it was possible
for _endAnimatedResize to re-enter via synchronizeDynamicViewportUpdate()/didCommitLayerTree(),
causing us to use a nil _resizeAnimationView for scale computations, thus setting a zero
scale on the WKContentView.

Fix by checking _dynamicViewportUpdateMode again after the call to synchronizeDynamicViewportUpdate(),
and do a belt-and-braces check for a nil _resizeAnimationView.

• UIProcess/API/Cocoa/WKWebView.mm:

(-[WKWebView _endAnimatedResize]):

Location:

trunk/Source/WebKit2

Files:

• ChangeLog (modified) (1 diff)
• UIProcess/API/Cocoa/WKWebView.mm (modified) (1 diff)

trunk/Source/WebKit2/ChangeLog

@@ +1 @@
+2016-12-20  Simon Fraser  <simon.fraser@apple.com>
+
+        [iOS WK2] Switching or closing a tab leads to all-white tab content if the status bar is double height
+        https://bugs.webkit.org/show_bug.cgi?id=166286
+        rdar://problem/29593525
+
+        Reviewed by Tim Horton.
+
+        A double-height status bar triggers view resize while snapshotting in the background,
+        which also triggers calls to _endAnimatedResize on tab resume. However, it was possible
+        for _endAnimatedResize to re-enter via synchronizeDynamicViewportUpdate()/didCommitLayerTree(),
+        causing us to use a nil _resizeAnimationView for scale computations, thus setting a zero
+        scale on the WKContentView.
+
+        Fix by checking _dynamicViewportUpdateMode again after the call to synchronizeDynamicViewportUpdate(),
+        and do a belt-and-braces check for a nil _resizeAnimationView.
+
+        * UIProcess/API/Cocoa/WKWebView.mm:
+        (-[WKWebView _endAnimatedResize]):
+
 2016-12-20  Andy Estes  <aestes@apple.com>
 

trunk/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm

@@ -4305 +4305 @@
     _page->synchronizeDynamicViewportUpdate();
 
+    // synchronizeDynamicViewportUpdate() may cause this function to re-enter via _didCommitLayerTree, so check _dynamicViewportUpdateMode again.
+    if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::NotResizing)
+        return;
+
+    if (!_resizeAnimationView) {
+        // Paranoia. If _resizeAnimationView is null we'll end up setting a zero scale on the content view.
+        ASSERT_NOT_REACHED();
+        _dynamicViewportUpdateMode = DynamicViewportUpdateMode::NotResizing;
+        [_contentView setHidden:NO];
+        return;
+    }
+    
     NSUInteger indexOfResizeAnimationView = [[_scrollView subviews] indexOfObject:_resizeAnimationView.get()];
     [_scrollView insertSubview:_contentView.get() atIndex:indexOfResizeAnimationView];