Bug 78943 - Avoid compositing empty elements
Summary: Avoid compositing empty elements
Status: RESOLVED DUPLICATE of bug 63499
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Xianzhu Wang
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2012-02-17 16:20 PST by Xianzhu Wang
Modified: 2012-03-14 14:32 PDT (History)
6 users (show)

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Description Xianzhu Wang 2012-02-17 16:20:32 PST 
Google+ has a zero-height fixed-position element beneath the main content.
we enable compositing for fixed-position elements, which means lots of content divs
overlap it and are also composited.  -- husky@chromium.org
Comment 1 Xianzhu Wang 2012-02-23 11:15:45 PST 
Just verified that the patch of bug 78186 also fixed this bug, because an empty rect doesn't intersect any other rect.
Comment 2 Xianzhu Wang 2012-02-23 15:59:46 PST 
Sorry my previous verification was not complete. Bug 78186 can prevents empty fixed position element that is at the bottom layer from being composited (and in turn may prevent elements over it from being composited).

If an empty element is over another composited element, it may still be composited because the intersect condition change in bug 34065. Would it be better to fix issue of cliprect cache instead of changing the overlap checking for bug 34065 that will cause unnecessary compositing layers?

We also tried to disable cliprect cache, and didn't see visible performance change.
Comment 3 Xianzhu Wang 2012-03-14 14:32:46 PDT 

*** This bug has been marked as a duplicate of bug 63499 ***