1343436 - feTurbulence (SVG filter) alpha channel output is incorrect

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[Amelia Bellamy-Royds]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce:

Create an SVG filter with
<feTurbulence type="fractalNoise" baseFrequency="0"/>
or
<feTurbulence type="fractalNoise"/>
(because 0 is the default value for baseFrequency)
and apply to an element.


Actual results:

Firefox returns a transparent rectangle.


Expected results:

For a turbulence filter of type="fractalNoise", the zero-frequency result should be 50% alpha 50% gray.

This is probably an over-eager optimization, since for type="turbulence", the zero-frequency result is transparent black.

Spec: https://drafts.fxtf.org/filters/#feTurbulenceElement
Test site: http://codepen.io/AmeliaBR/pen/zZxozG/?editors=1100
Discussion re clarifying the spec prose: https://github.com/w3c/fxtf-drafts/issues/112

Comment 1

[Markus Stange [:mstange]]

Attachment: Bug 1343436 - Fix filter result for baseFrequency="0" type="fractalNoise".

Review commit: https://reviewboard.mozilla.org/r/116290/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/116290/

Comment 2

[Robert Longson [:longsonr]]

Comment on attachment 8842434 [details]
Bug 1343436 - Fix filter result for baseFrequency="0" type="fractalNoise".

https://reviewboard.mozilla.org/r/116290/#review118006

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/55aa0d9957fb
Fix filter result for baseFrequency="0" type="fractalNoise". r=longsonr+218550

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/55aa0d9957fb