Bug 130015

Summary: [CSS Regions] Hit-testing is not working properly inside scrollable regions
Product: WebKit Reporter: Radu Stavila <stavila>
Component: CSSAssignee: Radu Stavila <stavila>
Status: RESOLVED FIXED    
Severity: Normal CC: commit-queue, darin, esprehn+autocc, glenn, kondapallykalyan, simon.fraser, WebkitBugTracker
Priority: P2 Keywords: AdobeTracked
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 57312    
Attachments:
Description Flags
Patch none

Description Radu Stavila 2014-03-10 04:04:41 PDT 
Hit-testing on elements inside scrollable regions does not take the region's scroll offset into consideration.
Comment 1 Radu Stavila 2014-03-10 10:05:01 PDT 
Created attachment 226313 [details]
Patch
Comment 2 Darin Adler 2014-03-10 10:12:31 PDT 
Comment on attachment 226313 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=226313&action=review

> Source/WebCore/rendering/RenderLayer.cpp:6879
> +    IntSize scrolledContentOffset = region->fragmentContainer().hasOverflowClip() ? region->fragmentContainer().scrolledContentOffset() : IntSize();

Why would we want to skip the call to scrolledContentOffset is the container does not handle overflow? Wouldn’t the container correctly return 0,0 in that case? This seems mysterious enough that you might want to write a comment.
Comment 3 Radu Stavila 2014-03-10 10:20:37 PDT 
Comment on attachment 226313 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=226313&action=review

>> Source/WebCore/rendering/RenderLayer.cpp:6879
>> +    IntSize scrolledContentOffset = region->fragmentContainer().hasOverflowClip() ? region->fragmentContainer().scrolledContentOffset() : IntSize();
> 
> Why would we want to skip the call to scrolledContentOffset is the container does not handle overflow? Wouldn’t the container correctly return 0,0 in that case? This seems mysterious enough that you might want to write a comment.

The first line of the RenderBox::scrolledContentOffset() method is ASSERT(hasOverflowClip());
Comment 4 Antti Koivisto 2014-03-10 10:27:58 PDT 
Comment on attachment 226313 [details]
Patch

r=me with the informative comment Darin asked for.
Comment 5 Radu Stavila 2014-03-10 10:33:10 PDT 
After discussing with Antti on IRC, we decided to not add the comment, since throughout the code, every time the scrolledContentOffset is used, it's preceeded by the hasOverflowClip check. I will submit an issue to move the check inside the scrolledContentOffset method itself.
Comment 6 WebKit Commit Bot 2014-03-10 11:42:58 PDT 
Comment on attachment 226313 [details]
Patch

Clearing flags on attachment: 226313

Committed r165388: <http://trac.webkit.org/changeset/165388>
Comment 7 WebKit Commit Bot 2014-03-10 11:43:02 PDT 
All reviewed patches have been landed.  Closing bug.