Bug 255208

Summary:

CanvasRenderingContext2D drawImage doesn't work correctly with transform when copying from self

Product:

WebKit

Reporter:

Gregg Tavares <gman>

Component:

Canvas

Assignee:

Said Abou-Hallawa <sabouhallawa>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

dino, heycam, karlcow, sabouhallawa, simon.fraser, webkit-bug-importer

Priority:

Keywords:

BrowserCompat, InRadar

Version:

Safari Technology Preview

Hardware:

All

OS:

All

Attachments:

Description	Flags
repo of canvas drawImage issue	none

Description Gregg Tavares 2023-04-09 16:55:30 PDT

Created attachment 465824 [details]
repo of canvas drawImage issue

Here's an example where a canvas is 400x200

It sets the scale to 2x2  eg: ctx.scale(2,2)
It then copies the canvas to itself with

    ctx.drawImage(ctx.canvas
      2, 0, 398, 200,    // these values are in source pixels (ie, 400x200)
      0, 0, 199, 100);   // these values are in transformed pixels (ie, 200x100)

this works in Firefox and Chrome but fails in Safari

https://jsgist.org/?src=fedaf98f88bb57622af24481944bbefc

Attached a stand alone repo

Comment 1 Radar WebKit Bug Importer 2023-04-10 12:13:05 PDT

<rdar://problem/107844963>

Comment 2 Said Abou-Hallawa 2023-04-10 12:29:12 PDT

Pull request: https://github.com/WebKit/WebKit/pull/12580

Comment 3 EWS 2023-04-11 15:01:47 PDT

Committed 262841@main (aa025e46a961): <https://commits.webkit.org/262841@main>

Reviewed commits have been landed. Closing PR #12580 and removing active labels.