RESOLVED WORKSFORME 118576
REGRESSION(r120021): Weird color differences on Acid3 test. 
https://bugs.webkit.org/show_bug.cgi?id=118576
Summary REGRESSION(r120021): Weird color differences on Acid3 test.
Zev Eisenberg
Reported 2013-07-11 14:20:52 PDT
Created attachment 206488 [details] screen recording of the bug Steps to Reproduce: 1. Go to http://acid3.acidtests.org in Safari or Webkit Nightly. I was able to reproduce this in 6.0.5 (8536.30.1) and 6.0.5 (8536.30.1, 538+). 2. Command-click the Reference Rendering link to open it in a new tab. 3. Switch back and forth between the two tabs. Expected Results: The colors in the six colorful squares are identical between the real test and the reference rendering. Actual Results: The colors are different. To my eyes, the blue square is the most obviously a different color, but sampling the attached video with e.g. DigitalColor Meter.app on a Mac will reveal that they are all different colors. Here's where it gets weird: if I refresh the reference rendering page, as shown in the attached video, the colors then match up perfectly between the reference rendering and the actual test. Regression: I believe this started within the last several months, certainly less than a year. I noticed it a while ago, but it didn't occur to me to report it until just now. Notes: This problem does not seem to exist in Firefox. The current stable build of Chrome fails miserably at the Acid3 test (no colored squares show up), so I was unable to determine whether it happens there. As far as I can tell from screenshots, the problem is not present in Mobile Safari on an iPad mini running iOS 6.1.3.
Attachments
screen recording of the bug (3.56 MB, video/quicktime)
2013-07-11 14:20 PDT, Zev Eisenberg 		no flags
Details
test case (122 bytes, text/html)
2013-07-16 06:28 PDT, alan baradlay 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
alan baradlay
Comment 1 2013-07-16 06:28:43 PDT
Created attachment 206773 [details] test case To repo this bug, click on the link (with command button down) and manually switch over to the new tab. if the <a> has 'target=blank' so that the tab gets activated right after the navigation, the color diff does not occur.
Simon Fraser (smfr)
Comment 2 2013-07-16 08:25:41 PDT
Possibly fixed in Mavericks?
Zev Eisenberg
Comment 3 2013-07-16 09:55:54 PDT
(In reply to comment #2) > Possibly fixed in Mavericks? I can not reproduce this in Mavericks beta 3. Does this mean it should be closed? What was the problem, and how was it fixed?
alan baradlay
Comment 4 2013-07-16 09:56:46 PDT
(In reply to comment #2) > Possibly fixed in Mavericks? Indeed. Can't repro on Mavericks.
Simon Fraser (smfr)
Comment 5 2013-07-16 10:02:43 PDT
QuartzCore uses two different code paths (one when offscreen) for CG rendering, and one of them has color matching bugs.
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