Bug 258672

Summary:

Regression (iOS 17.0 beta 2): Canvas Layering of Images Renders Differently

Product:

WebKit

Reporter:

M <heystoneybatter>

Component:

Canvas

Assignee:

Nobody <webkit-unassigned>

Status:

RESOLVED CONFIGURATION CHANGED

Severity:

Normal

CC:

dino, heycam, sabouhallawa, webkit-bug-importer

Priority:

Keywords:

InRadar

Version:

Safari 17

Hardware:

iPhone / iPad

OS:

Other

Attachments:

Description	Flags
Image showing comparison of the two renderings (prior Safari vs 17.0 Beta 2)	none

Description M 2023-06-29 06:24:54 PDT

Created attachment 466866 [details]
Image showing comparison of the two renderings (prior Safari vs 17.0 Beta 2)

Overview:
I was testing the new iPadOS 17.0 Beta 2 (21A5268h) and noticed a bug in how Canvas rendered layered images. I hadn't noticed this issue in 17 Beta 1 (or any prior version of Safari/WebKit), so I believe it was introduced in Beta 2.

The bug can be seen at this URL using an iPad on 17.0 Beta 2:
https://webkit-canvas-test.pages.dev


Steps To Reproduce:
The code at the link above loads a photo of a man (man.jpeg) to the canvas and then loads another image (noise.png) on top of that. The second image is of a subtle noise pattern that should render across the canvas.

Actual Results:
On iPadOS 17 Beta 2, the canvas renders a man covered in an INTENSE noise pattern. It is almost as if globalCompositeOperation is something other than the default.

What You Should See: 
All prior versions of Safari/Webkit will just show a man holding a frying pan with a subtle amount of noise on the image (see attached). The latest Safari Technology Preview release 173 on my MacBook Pro renders this correctly as well. I do not have an iPhone to test on this release yet though, so the bug may be on both iOS and iPadOS.

Build:
Issues seen on iPadOS 17.0 (21A5268h) on an iPad Mini 6th Generation

Comment 1 Radar WebKit Bug Importer 2023-06-29 10:28:56 PDT

<rdar://problem/111520394>

Comment 2 Cameron McCormack (:heycam) 2023-07-12 19:57:50 PDT

This should be fixed in the iPadOS public beta released today.  Please let me know if you are still seeing this issue, thanks!

Comment 3 M 2023-07-13 02:52:28 PDT

(In reply to Cameron McCormack (:heycam) from comment #2)
> This should be fixed in the iPadOS public beta released today.  Please let
> me know if you are still seeing this issue, thanks!

Thank you Cameron. I can confirm that this was fixed and I am no longer seeing the issue. Great work!