[Webkit-unassigned] [Bug 86026] New: [QT 32 bit] Child div overlay on parent div results in image diff when it shouldn't

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=86026

           Summary: [QT 32 bit] Child div overlay on parent div results in
                    image diff when it shouldn't
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Linux
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: CSS
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: dtharp at codeaurora.org


Attached are two html files: div-overlay.html and div-overlay-expected.html (reference test).

When div-overlay.html is run in new-run-webkit-tests, it's output is pixel compared to the output from div-overlay-expected.html (presuming they are both in the same directory).

The design of the test is simple.  A parent div is created 300px wide by 100px tall with a red background.  A child div is created 300px wide by 100px tall with a green background. The rendered image should be a 300x100 green rectangle.  

The reference test is the same except the parent div has a *green* background. The rendered image should be the same as the test html: a 300x100 green rectangle.

On all ports except QT Linux 32-bit, this test will pass. 

The failure on QT Linux 32-bit is strange:
1. Visually, there is no difference detectable.
2. The output pngs' checksums are different, and the file sizes are off by 3 bytes.
3. Looking at the output pngs in gimp, I am able to inspect the green pixels. Both pngs' "green" are #008000
4. The diff png generated is simply a large completely black square, which I believe means no diffs (I verified by changing text and observing that the changed text appears white inside the black square).
5. Note that if the reference test is changed such that the parent div has a red background, the test passes. This would seem to indicate that somehow the red background is visible when Qt 32-bit renders, but close inspection of the resultant pngs does not confirm this.

Attaching the pngs as well.

-- 
Configure bugmail: https://bugs.webkit.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.