Bug 222112 - WebKit renders APNGs with corrupted palettes
Summary: WebKit renders APNGs with corrupted palettes
Status: RESOLVED MOVED
Alias: None
Product: WebKit
Classification: Unclassified
Component: Images (show other bugs)
Version: Safari 14
Hardware: iPhone / iPad iOS 14
: P2 Normal
Assignee: Nobody
URL: https://bobatealee.com/hosting/webkit...
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2021-02-18 08:59 PST by trashboyjet
Modified: 2021-02-19 19:09 PST (History)
2 users (show)

See Also:

Attachments
Test Case Reduction (182 bytes, text/html)
2021-02-18 08:59 PST, trashboyjet 		no flags Details
Test Case Reduction (183 bytes, text/html)
2021-02-19 12:45 PST, trashboyjet 		no flags Details
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Description trashboyjet 2021-02-18 08:59:12 PST 
Created attachment 420835 [details]
Test Case Reduction

It appears that WebKit has issues with rendering certain .apng files. I've tested on multiple browsers utilizing WebKit, with a few images, and they generally have corrupted palettes/flickering that does not occur on non-WebKit browsers.

To reproduce this error, simply visit one of the pages attached to this report. It should happen consistently.

By doing the above, you'll see the .apng file flicker or have transparency/palette corruption.

The expected result is to have this function as it does on any non-WebKit browser.

Here's 4 different WebKit browsers I tested on where the issue consistently occurs:
- Safari 14 (macOS)
- Safari 14 (iOS)
- Firefox 31 (iOS)
- Chrome 87.0.4280.77 (iOS)

I've also tested non-WebKit browsers, and the issue isn't present:
- Firefox 85.0.2 (Windows)
- Chrome 88.0.4324.150(Windows)
- Firefox 85.0.1 (macOS)
- Chrome 88.0.4324.182 (macOS)
- Brave 1.19.86 (macOS)

If you need any more information, please let me know.
Comment 1 trashboyjet 2021-02-19 12:45:00 PST 
Comment on attachment 420835 [details]
Test Case Reduction

><!DOCTYPE html>
><html>
>	<head>
>		<title>Test Case Reduction</title>
>	</head>
>
>	<body>
>		<img src="https://bobatealee.com/hosting/webkitbug/ohyeah.png"></img>
>	</body>
></html>
Comment 2 trashboyjet 2021-02-19 12:45:58 PST 
Created attachment 421015 [details]
Test Case Reduction
Comment 3 Alexey Proskuryakov 2021-02-19 18:41:26 PST 
It almost looks intentional on this example, but comparing to other browsers, it's not.
Comment 4 Simon Fraser (smfr) 2021-02-19 19:09:48 PST 
rdar://74547307
Comment 5 Simon Fraser (smfr) 2021-02-19 19:09:59 PST 
Tracked internally.