[Webkit-unassigned] [Bug 220576] New: Setting filter on image before it's added in the DOM causes weird rendering when feComponentTransfer is present

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=220576

            Bug ID: 220576
           Summary: Setting filter on image before it's added in the DOM
                    causes weird rendering when feComponentTransfer is
                    present
           Product: WebKit
           Version: Safari Technology Preview
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: SVG
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: xidorn-webkit at upsuper.org
                CC: zimmermann at kde.org

Created attachment 417504

  --> https://bugs.webkit.org/attachment.cgi?id=417504&action=review

testcase

Steps to reproduce:
1. open the testcase
2. click the "Set filter" button

Expected result:
The image becomes blurred.

Actual result:
The image is blurred, but also stretched a bit.

(I've observed even worse distortion when more complicated filters are added.)

I've tested Firefox and Chrome, and neither of them has this problem.

After some diagnose, I think this is because `feComponentTransfer` doesn't work correctly when the SVG is not somehow rendered. This behavior can be easily reproduced if the SVG element is `display: none`. (Note that Firefox shows nothing when SVG element is `display: none` though, not sure whose behavior is correct here.)

That makes me think that the distorted state being persisted is probably related to bug 99996 that even if the SVG element is correctly rendered, the filter result is not updated accordingly.

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