Created attachment 357545 [details]
an unexpected 1px red line on
a JPEG file.
I found an issue with JPEG drawing on iOS 12 devices.
An unexpected 1px line appears on a image when I use context.drawImage() method of html to show a specified part of a JPEG file.
It doesn't occur when using iOS12 simulators or iOS11 devices.
[Steps to reproduce the problem]
1. Open 'index.html' on Safari using iPhone/iPad on iOS12.
This html file shows a specified part of each following file.
2. An unexpected 1px red line appears on 'test.jpg' image. No problems with the other files, though.
[What is the expected behavior?]
No unexpected lines appear on a JPEG image like the other file formats ( : png, jp2, gif).
[What went wrong?]
An unexpected 1px red line appears on a JPEG image.
[Is it a problem with a plugin?]
[Did this work before?]
[Does this work in other browsers?]
Created attachment 357546 [details]
a html file used for this test.
Created attachment 357548 [details]
This appears to be a bug in the underlying graphics framework, not WebKit.
This will be fixed in a future iOS version.