Bug 103424 - [Qt] A new compositing bug uncovered by r135859
Summary: [Qt] A new compositing bug uncovered by r135859
Status: RESOLVED INVALID
Alias: None
Product: WebKit
Classification: Unclassified
Component: New Bugs (show other bugs)
Version: 420+
Hardware: All All
: P2 Normal
Assignee: Nobody
URL:
Keywords:
Depends on:
Blocks: 87008 103275
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Reported: 2012-11-27 09:06 PST by Csaba Osztrogonác
Modified: 2014-02-03 03:23 PST (History)
5 users (show)

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Description Csaba Osztrogonác 2012-11-27 09:06:51 PST
fast/backgrounds/background-opaque-images-over-color.html started to
fail on Qt after r135859 and r135861 - refactoring to reftest

See https://bugs.webkit.org/show_bug.cgi?id=103275 for details.

Image diff on the Qt bot: http://build.webkit.sed.hu/results/x86-64%20Linux%20Qt%20Release/r135862%20%2845465%29/fast/backgrounds/background-opaque-images-over-color-diffs.html
Comment 1 Csaba Osztrogonác 2012-11-27 09:13:08 PST
I skipped it by r135865. Please unskip it with the proper fix.
Comment 2 Allan Sandfeld Jensen 2013-01-15 09:54:49 PST
It seems to be case 3 and case 8 that that fails.

  <div id="case_3" class="redBack" style="background-image: -webkit-cross-fade(url(../../http/tests/multipart/resources/green-100x100.png), url(../../http/tests/multipart/resources/green-100x100.png), 50%)"></div>

   <div id="case_9" class="redBack" style="background-repeat: no-repeat; background-image: url(../../http/tests/multipart/resources/green-100x100.png),url(resources/64x32-red.png)"></div>

 So it appears cross-fading between two identical images produces something that is not an identical image.
Comment 3 Allan Sandfeld Jensen 2013-01-16 02:23:46 PST
A quick investigation shows that cross-fading images is crossplatform code. It does however rely on a PLUS composition to ensure the two images opacity adds up to 100%. It could appear that QPainter does not composition opacity values set by QPainter::setOpacity but only thoses in the alpha values of painted images.
Comment 4 Jocelyn Turcotte 2014-02-03 03:23:44 PST
=== Bulk closing of Qt bugs ===

If you believe that this bug report is still relevant for a non-Qt port of webkit.org, please re-open it and remove [Qt] from the summary.

If you believe that this is still an important QtWebKit bug, please fill a new report at https://bugreports.qt-project.org and add a link to this issue. See http://qt-project.org/wiki/ReportingBugsInQt for additional guidelines.