RESOLVED DUPLICATE of bug 200026 226254
Premultiplication handled incorrectly for WebGL canvases display and upload 
https://bugs.webkit.org/show_bug.cgi?id=226254
Summary Premultiplication handled incorrectly for WebGL canvases display and upload
Kai Ninomiya
Reported 2021-05-25 17:54:55 PDT
Created attachment 429720 [details] Reproduction case 1. Open https://codepen.io/kainino0x/pen/oNZwoJQ (or the attached file) Expected result: The six WebGL-rendered canvases should match the six 2d-rendered canvases (with the exception described in the test case). Actual result: See attached. From inspection, I think (but I'm not sure): - Canvases with premultiplyAlpha:false are treated as if they have premultiplyAlpha:true (both when they are displayed, and when they are used as sources to texImage2D). - texImage2D from webgl canvas sources with premultiplyAlpha:false are incorrectly y-flipped. On macOS 11.3.1 (20E241): - Pass: Chrome - 92.0.4515.7 (Official Build) canary (x86_64) - Pass: Firefox - 90.0a1 (2021-05-18) (64-bit) - FAIL: Safari Stable - Version 14.1 (16611.1.21.161.6) - FAIL: Safari Technology Preview - Release 124 (Safari 14.2, WebKit 16612.1.11.10)
Attachments
Reproduction case (5.58 KB, text/html)
2021-05-25 17:54 PDT, Kai Ninomiya 		no flags
Details
Screenshot of the expected behavior (in Chrome, but Firefox is same) (49.96 KB, image/png)
2021-05-25 17:55 PDT, Kai Ninomiya 		no flags
Details
Screenshot of Safari Technology Preview's (incorrect) behavior (51.08 KB, image/png)
2021-05-25 17:55 PDT, Kai Ninomiya 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Kai Ninomiya
Comment 1 2021-05-25 17:55:25 PDT
Created attachment 429721 [details] Screenshot of the expected behavior (in Chrome, but Firefox is same)
Kai Ninomiya
Comment 2 2021-05-25 17:55:55 PDT
Created attachment 429722 [details] Screenshot of Safari Technology Preview's (incorrect) behavior
Kimmo Kinnunen
Comment 3 2021-05-26 01:36:01 PDT
Thanks for the repro. I believe the bugs in depends on are the earlier reports of these.
Radar WebKit Bug Importer
Comment 4 2021-06-01 17:55:17 PDT
<rdar://problem/78741173>
Kimmo Kinnunen
Comment 5 2022-04-22 00:25:17 PDT
*** This bug has been marked as a duplicate of bug 200026 ***
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