Changeset 225981 in webkit

Timestamp:

Dec 15, 2017 1:12:43 PM (6 years ago)

Author:

Simon Fraser

Message:

Rotating when zoomed in with fingers down can result in a broken tab
​https://bugs.webkit.org/show_bug.cgi?id=180859
rdar://problem/34532817

Reviewed by Tim Horton.

If you zoom in fully, then, with two fingers down, rotate the iPhone and rotate back,
then the tab can get into a broken state where the WKContentView has a non-zero position
which may push it entirely off-screen. The tab never recovers.

This is caused by a bug in UIKit (rdar://problem/36065495) so work around it by always
re-setting the position of the content view after zooming. We initialize contentView.frame
from self.bounds, so setting the position (via "center") to the bounds origin should always be safe.

• UIProcess/API/Cocoa/WKWebView.mm:

(-[WKWebView scrollViewDidEndZooming:withView:atScale:]):

Location:

trunk/Source/WebKit

Files:

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

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2017-12-14  Simon Fraser  <simon.fraser@apple.com>
+
+        Rotating when zoomed in with fingers down can result in a broken tab
+        https://bugs.webkit.org/show_bug.cgi?id=180859
+        rdar://problem/34532817
+
+        Reviewed by Tim Horton.
+
+        If you zoom in fully, then, with two fingers down, rotate the iPhone and rotate back,
+        then the tab can get into a broken state where the WKContentView has a non-zero position
+        which may push it entirely off-screen. The tab never recovers.
+
+        This is caused by a bug in UIKit (rdar://problem/36065495) so work around it by always
+        re-setting the position of the content view after zooming. We initialize contentView.frame
+        from self.bounds, so setting the position (via "center") to the bounds origin should always be safe.
+
+        * UIProcess/API/Cocoa/WKWebView.mm:
+        (-[WKWebView scrollViewDidEndZooming:withView:atScale:]):
+
 2017-12-15  Brady Eidson  <beidson@apple.com>
 

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

@@ -2379 +2379 @@
 {
     ASSERT(scrollView == _scrollView);
+    // FIXME: remove when rdar://problem/36065495 is fixed.
+    // When rotating with two fingers down, UIScrollView can set a bogus content view position.
+    // "Center" is top left because we set the anchorPoint to 0,0.
+    [_contentView setCenter:self.bounds.origin];
+
     [self _scheduleVisibleContentRectUpdateAfterScrollInView:scrollView];
     [_contentView didZoomToScale:scale];