Title: [133225] trunk/Source/WebKit/mac
- Revision
- 133225
- Author
- aro...@webkit.org
- Date
- 2012-11-01 13:57:46 -0700 (Thu, 01 Nov 2012)
Log Message
[WK1] Fixed-position elements jiggle up and down slightly during scrolling on a Retina display
https://bugs.webkit.org/show_bug.cgi?id=100957
Reviewed by Simon Fraser.
WebCore doesn't yet support subpixel scrolling. WebKit2 forces
scrolling to always be integral. Now WebKit1 forces this as well.
I'm not sure how to write a test for this.
* WebView/WebDynamicScrollBarsView.mm:
(shouldRoundScrollOrigin): Returns YES if there are any position:fixed
or position:sticky elements in the page.
(-[WebDynamicScrollBarsView scrollClipView:toPoint:]): Round the
scroll origin to the nearest pixel if needed.
Modified Paths
Diff
Modified: trunk/Source/WebKit/mac/ChangeLog (133224 => 133225)
--- trunk/Source/WebKit/mac/ChangeLog 2012-11-01 20:54:20 UTC (rev 133224)
+++ trunk/Source/WebKit/mac/ChangeLog 2012-11-01 20:57:46 UTC (rev 133225)
@@ -1,3 +1,21 @@
+2012-11-01 Adam Roben <aro...@webkit.org>
+
+ [WK1] Fixed-position elements jiggle up and down slightly during scrolling on a Retina display
+ https://bugs.webkit.org/show_bug.cgi?id=100957
+
+ Reviewed by Simon Fraser.
+
+ WebCore doesn't yet support subpixel scrolling. WebKit2 forces
+ scrolling to always be integral. Now WebKit1 forces this as well.
+
+ I'm not sure how to write a test for this.
+
+ * WebView/WebDynamicScrollBarsView.mm:
+ (shouldRoundScrollOrigin): Returns YES if there are any position:fixed
+ or position:sticky elements in the page.
+ (-[WebDynamicScrollBarsView scrollClipView:toPoint:]): Round the
+ scroll origin to the nearest pixel if needed.
+
2012-10-31 Anders Carlsson <ander...@apple.com>
Fix build.
Modified: trunk/Source/WebKit/mac/WebView/WebDynamicScrollBarsView.mm (133224 => 133225)
--- trunk/Source/WebKit/mac/WebView/WebDynamicScrollBarsView.mm 2012-11-01 20:54:20 UTC (rev 133224)
+++ trunk/Source/WebKit/mac/WebView/WebDynamicScrollBarsView.mm 2012-11-01 20:57:46 UTC (rev 133225)
@@ -29,7 +29,6 @@
#import "WebFrameInternal.h"
#import "WebFrameView.h"
#import "WebHTMLViewInternal.h"
-#import <WebCore/Frame.h>
#import <WebCore/FrameView.h>
#import <WebKitSystemInterface.h>
@@ -188,6 +187,36 @@
return _private->verticalScrollingAllowedButScrollerHidden || [self hasVerticalScroller];
}
+static BOOL shouldRoundScrollOrigin(WebDynamicScrollBarsView *view)
+{
+ NSView *documentView = [view documentView];
+ if (![documentView isKindOfClass:[WebHTMLView class]])
+ return NO;
+
+ Frame* frame = core([(WebHTMLView *)documentView _frame]);
+ if (!frame)
+ return NO;
+
+ FrameView *frameView = frame->view();
+ if (!frameView)
+ return NO;
+
+ return frameView->hasViewportConstrainedObjects();
+}
+
+- (void)scrollClipView:(NSClipView *)clipView toPoint:(NSPoint)point
+{
+ if (shouldRoundScrollOrigin(self)) {
+ // WebCore isn't yet able to handle subpixel scrolling, as can happen on Retina displays. For
+ // now we'll round to the nearest pixel. Once subpixel layout is enabled in WebCore we may be
+ // able to remove this method entirely.
+ point.x = round(point.x);
+ point.y = round(point.y);
+ }
+
+ [super scrollClipView:clipView toPoint:point];
+}
+
@end
@implementation WebDynamicScrollBarsView (WebInternal)
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