Bug 135637 – [Mac] Unable to scroll to bottom of nested scrollable areas

• Status: RESOLVED
• Resolution: FIXED
• Component: Layout and Rendering

[Brent Fulgham]

A user reported that "On some pages, I can’t scroll to the bottom of the page using the trackpad, but I can get there with the down arrow key."

This seems to be an issue with sub-pixel calculations when a scrollable <div> is nested inside another scrollable <div>.

[Brent Fulgham]

<rdar://problem/17910241>

[Brent Fulgham]

Created attachment 236077 [details]
Patch

[zalan]

Comment on attachment 236077 [details]
Patch

I don't know much about scrolling, but wouldn't it make sense to fix those totalSize()/visibleSize() values too? It seems like we can't use them to calculate the scroll size value anymore and that could potentially cause other issues throughout the code -wherever they are used (if they are used at all)

[Simon Fraser (smfr)]

Comment on attachment 236077 [details]
Patch

I think you should be able to make a layout test for this.

[Darin Adler]

Comment on attachment 236077 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=236077&action=review

> Source/WebCore/rendering/RenderLayer.cpp:2603
> +    IntSize scrollRange = maximumScrollPosition() - minimumScrollPosition();
> +    if (orientation == HorizontalScrollbar)
> +        return scrollRange.width();
> +
> +    return scrollRange.height();

The blank line makes this read awkwardly. I think ? : would be nicer.

[Darin Adler]

Comment on attachment 236077 [details]
Patch

Why no regression test?

[Build Bot]

Comment on attachment 236077 [details]
Patch

Attachment 236077 [details] did not pass mac-wk2-ews (mac-wk2):
Output: http://webkit-queues.appspot.com/results/4751358750097408

New failing tests:
ietestcenter/css3/bordersbackgrounds/background-attachment-local-scrolling.htm

[Build Bot]

Created attachment 236079 [details]
Archive of layout-test-results from webkit-ews-13 for mac-mountainlion-wk2

The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews.
Bot: webkit-ews-13  Port: mac-mountainlion-wk2  Platform: Mac OS X 10.8.5

[Build Bot]

Comment on attachment 236077 [details]
Patch

Attachment 236077 [details] did not pass mac-ews (mac):
Output: http://webkit-queues.appspot.com/results/4914987340398592

New failing tests:
ietestcenter/css3/bordersbackgrounds/background-attachment-local-scrolling.htm

[Build Bot]

Created attachment 236080 [details]
Archive of layout-test-results from webkit-ews-05 for mac-mountainlion

The attached test failures were seen while running run-webkit-tests on the mac-ews.
Bot: webkit-ews-05  Port: mac-mountainlion  Platform: Mac OS X 10.8.5

[Build Bot]

Comment on attachment 236077 [details]
Patch

Attachment 236077 [details] did not pass mac-ews (mac):
Output: http://webkit-queues.appspot.com/results/6105597372006400

New failing tests:
ietestcenter/css3/bordersbackgrounds/background-attachment-local-scrolling.htm

[Build Bot]

Created attachment 236081 [details]
Archive of layout-test-results from webkit-ews-04 for mac-mountainlion

The attached test failures were seen while running run-webkit-tests on the mac-ews.
Bot: webkit-ews-04  Port: mac-mountainlion  Platform: Mac OS X 10.8.5

[Brent Fulgham]

(In reply to comment #6)
> (From update of attachment 236077 [details])
> Why no regression test?

Yes - I'm working on that now!

[Brent Fulgham]

Created attachment 236108 [details]
Patch

[Brent Fulgham]

Committed r172160: <http://trac.webkit.org/changeset/172160>