Bug 120535 – Require layout when -webkit-overflow-scrolling changes

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Daniel Bates]

We should perform a layout when the value of -webkit-overflow-scrolling changes as -webkit-overflow-scrolling creates a stacking context.

[Daniel Bates]

Created attachment 210129 [details]
Patch and layout test

I'm unhappy with the layout test included with the patch, which tests that a change to -webkit-overflow-scrolling causes a repaint. I tried to write a test to show that -webkit-overflow-scrolling creates a stacking context by detecting a difference in an element's z-index after changing the value of it's property -webkit-overflow-scrolling from auto to touch. I was unclear how to write such a test given the constraints that we only set z-index to 0 on an element with auto z-index, -webkit-overflow-scrolling: touch, and overflow: auto/hidden/scroll.  Does anyone have any insight/suggestions on how to write such a test or knows of a better way to test that we perform a layout when the value of -webkit-overflow-scrolling changes?

[Daniel Bates]

(In reply to comment #1)
> Created an attachment (id=210129) [details]
> Patch and layout test
> 
> [...] I was unclear how to write such a test given the constraints that we only set z-index to 0 on an element with auto z-index, -webkit-overflow-scrolling: touch, and overflow: auto/hidden/scroll.

*overflow: auto/scroll/overlay

[Build Bot]

Comment on attachment 210129 [details]
Patch and layout test

Attachment 210129 [details] did not pass mac-wk2-ews (mac-wk2):
Output: http://webkit-queues.appspot.com/results/1641037

New failing tests:
fast/repaint/overflow-scroll-touch-repaint.html

[Build Bot]

Created attachment 210144 [details]
Archive of layout-test-results from webkit-ews-14 for mac-mountainlion-wk2

The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews.
Bot: webkit-ews-14  Port: mac-mountainlion-wk2  Platform: Mac OS X 10.8.4

[Build Bot]

Comment on attachment 210129 [details]
Patch and layout test

Attachment 210129 [details] did not pass mac-ews (mac):
Output: http://webkit-queues.appspot.com/results/1660082

New failing tests:
fast/repaint/overflow-scroll-touch-repaint.html

[Build Bot]

Created attachment 210161 [details]
Archive of layout-test-results from webkit-ews-07 for mac-mountainlion

The attached test failures were seen while running run-webkit-tests on the mac-ews.
Bot: webkit-ews-07  Port: mac-mountainlion  Platform: Mac OS X 10.8.4

[Daniel Bates]

As far as I can tell ACCELERATED_OVERFLOW_SCROLLING is only enabled on iOS. Antonio Gomes seemed to imply that the BlackBerry port also enables ACCELERATED_OVERFLOW_SCROLLING in his remark in bug #120380, comment 8. Will skip test fast/repaint/overflow-scroll-touch-repaint.html on all non-iOS ports, except BlackBerry.

[Daniel Bates]

Committed r154993: <http://trac.webkit.org/changeset/154993>