Changeset 170783 in webkit

Timestamp:

Jul 3, 2014 5:48:14 PM (10 years ago)

Author:

Simon Fraser

Message:

[iOS WK2] Compositing layers draw outside page bounds
​https://bugs.webkit.org/show_bug.cgi?id=134619
<rdar://problem/16953222>

Reviewed by Benjamin Poulain.

With the new rubber-banding behavior, we no longer have the root content layer clipping all
the web layers, but this resulted in web layers which were moved outside the viewport by CSS
transforms not being clipped.

Fix by adding a clipping layer inside the scroll view, above _rootContentView. This layer
normally has the same bounds as the content, but when rubber-banding or pinching,
it takes the union of the content bounds and the rect used for fixed positioning.
To make scrolling work as expected in this scenario, when it has non-zero offset, it
has to compensate by setting its bounds origin.

The bounds of the clipping layer are updated on scrolling/zooming, and when the
layer commit tells us that the content size changed.

• UIProcess/API/Cocoa/WKWebView.mm:

(-[WKWebView _updateScrollViewBackground]):

• UIProcess/ios/WKContentView.mm:

(-[WKContentView initWithFrame:context:configuration:webView:]):
(-[WKContentView updateFixedClippingView:]):
(-[WKContentView didUpdateVisibleRect:unobscuredRect:unobscuredRectInScrollViewCoordinates:scale:minimumScale:inStableState:isChangingObscuredInsetsInteractively:]):
(-[WKContentView _didCommitLayerTree:]):

Location:

trunk/Source/WebKit2

Files:

• ChangeLog (modified) (1 diff)
• UIProcess/API/Cocoa/WKWebView.mm (modified) (1 diff)
• UIProcess/ios/WKContentView.mm (modified) (6 diffs)

trunk/Source/WebKit2/ChangeLog

@@ +1 @@
+2014-07-03  Simon Fraser  <simon.fraser@apple.com>
+
+        [iOS WK2] Compositing layers draw outside page bounds
+        https://bugs.webkit.org/show_bug.cgi?id=134619
+        <rdar://problem/16953222>
+
+        Reviewed by Benjamin Poulain.
+        
+        With the new rubber-banding behavior, we no longer have the root content layer clipping all
+        the web layers, but this resulted in web layers which were moved outside the viewport by CSS
+        transforms not being clipped.
+        
+        Fix by adding a clipping layer inside the scroll view, above _rootContentView. This layer
+        normally has the same bounds as the content, but when rubber-banding or pinching,
+        it takes the union of the content bounds and the rect used for fixed positioning.
+        To make scrolling work as expected in this scenario, when it has non-zero offset, it
+        has to compensate by setting its bounds origin.
+
+        The bounds of the clipping layer are updated on scrolling/zooming, and when the
+        layer commit tells us that the content size changed.
+
+        * UIProcess/API/Cocoa/WKWebView.mm:
+        (-[WKWebView _updateScrollViewBackground]):
+        * UIProcess/ios/WKContentView.mm:
+        (-[WKContentView initWithFrame:context:configuration:webView:]):
+        (-[WKContentView updateFixedClippingView:]):
+        (-[WKContentView didUpdateVisibleRect:unobscuredRect:unobscuredRectInScrollViewCoordinates:scale:minimumScale:inStableState:isChangingObscuredInsetsInteractively:]):
+        (-[WKContentView _didCommitLayerTree:]):
+
 2014-07-03  Brady Eidson  <beidson@apple.com>
 

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

@@ -665 +665 @@
     else
         color = _page->pageExtendedBackgroundColor();
+
     CGFloat zoomScale = contentZoomScale(self);
     CGFloat minimumZoomScale = [_scrollView minimumZoomScale];

trunk/Source/WebKit2/UIProcess/ios/WKContentView.mm

@@ -418 +418 @@
 
     RetainPtr<UIView> _rootContentView;
+    RetainPtr<UIView> _fixedClippingView;
     RetainPtr<WKInspectorIndicationView> _inspectorIndicationView;
     RetainPtr<WKInspectorHighlightView> _inspectorHighlightView;
@@ -445 +446 @@
     _rootContentView = adoptNS([[UIView alloc] init]);
     [_rootContentView layer].masksToBounds = NO;
-
-    [self addSubview:_rootContentView.get()];
+    
+    _fixedClippingView = adoptNS([[UIView alloc] init]);
+    [_fixedClippingView layer].masksToBounds = YES;
+    [_fixedClippingView layer].anchorPoint = CGPointZero;
+#ifndef NDEBUG
+    [[_fixedClippingView layer] setName:@"Fixed clipping"];
+#endif
+
+    [self addSubview:_fixedClippingView.get()];
+    [_fixedClippingView addSubview:_rootContentView.get()];
 
     [self setupInteraction];
@@ -554 +563 @@
 }
 
+- (void)updateFixedClippingView:(FloatRect)fixedPositionRectForUI
+{
+    FloatRect clippingBounds = [self bounds];
+    clippingBounds.unite(fixedPositionRectForUI);
+
+    [_fixedClippingView setCenter:clippingBounds.location()]; // Not really the center since we set an anchor point.
+    [_fixedClippingView setBounds:clippingBounds];
+}
+
 - (void)didUpdateVisibleRect:(CGRect)visibleRect unobscuredRect:(CGRect)unobscuredRect unobscuredRectInScrollViewCoordinates:(CGRect)unobscuredRectInScrollViewCoordinates
     scale:(CGFloat)zoomScale minimumScale:(CGFloat)minimumScale inStableState:(BOOL)isStableState isChangingObscuredInsetsInteractively:(BOOL)isChangingObscuredInsetsInteractively
@@ -571 +589 @@
 
     RemoteScrollingCoordinatorProxy* scrollingCoordinator = _page->scrollingCoordinatorProxy();
-    scrollingCoordinator->viewportChangedViaDelegatedScrolling(scrollingCoordinator->rootScrollingNodeID(), _page->computeCustomFixedPositionRect(_page->unobscuredContentRect(), zoomScale), zoomScale);
+    FloatRect fixedPositionRect = _page->computeCustomFixedPositionRect(_page->unobscuredContentRect(), zoomScale);
+    scrollingCoordinator->viewportChangedViaDelegatedScrolling(scrollingCoordinator->rootScrollingNodeID(), fixedPositionRect, zoomScale);
 
     if (auto drawingArea = _page->drawingArea())
@@ -578 +597 @@
     if (!withinEpsilon(oldDisplayedContentScale, zoomScale))
         [self _updateUnscaledView];
+        
+    [self updateFixedClippingView:fixedPositionRect];
 }
 
@@ -668 +689 @@
 {
     CGSize contentsSize = layerTreeTransaction.contentsSize();
-
-    [self setBounds:{CGPointZero, contentsSize}];
-    [_rootContentView setFrame:CGRectMake(0, 0, contentsSize.width, contentsSize.height)];
-    [_inspectorIndicationView setFrame:[self bounds]];
+    CGRect contentBounds = { CGPointZero, contentsSize };
+    CGRect oldBounds = [self bounds];
+
+    BOOL boundsChanged = !CGRectEqualToRect(oldBounds, contentBounds);
+    if (boundsChanged) {
+        [self setBounds:contentBounds];
+        [_rootContentView setFrame:contentBounds];
+        [_inspectorIndicationView setFrame:contentBounds];
+    }
 
     [_webView _didCommitLayerTree:layerTreeTransaction];
+    
+    if (boundsChanged) {
+        FloatRect fixedPositionRect = _page->computeCustomFixedPositionRect(_page->unobscuredContentRect(), [[_webView scrollView] zoomScale]);
+        [self updateFixedClippingView:fixedPositionRect];
+    }
+    
     [self _updateChangedSelection];
 }