Bug 139417 – Incorrect rounding in feGaussianBlur filter effect

• Status: NEW
• Component: SVG

[Said Abou-Hallawa]

Created attachment 242854 [details]
Safari-Rendering

Open the following SVG in WebKit:

<svg xmlns="http://www.w3.org/2000/svg" version="1.0">
  <filter id="f1">
    <feGaussianBlur in="SourceGraphic" stdDeviation="0.000000000000000000000000001" />
  </filter>
  <rect width="100%" height="100%" fill="lime"/>
  <circle fill="red" r="98" cx="200" cy="100"/>
  <circle fill="lime" r="100" cx="200" cy="100" filter="url(#f1)"/>
</svg>

Result: A lime background with the bottom arch of the blur effect although the stdDeviation of the effect is almost equal to zero.
Expected: A pure lime background is drawn. The same background can be drawn if the filter effect above is changed to be: <feGaussianBlur in="SourceGraphic" stdDeviation="0" />

NOTE: Both Chrome and FireFox display this SVG as expected.

[Radar WebKit Bug Importer]

<rdar://problem/19182781>

[Ahmad Saleem]

I am unable to reproduce this bug in Safari 16.4 and STP169. I think it might be something fixed macOS 13 update because some SVG bugs got fixed because of it.

If someone else confirm, we can close this as "RESOLVED CONFIGURATION CHANGED'.

[Karl Dubost]

Created attachment 466350 [details]
SVG test-case

It's not sure the svg below is testing what is required to exhibit the issue. 

Because the current rendering is the same in the 3 browsers, in the context of 

```
data:text/html,<svg xmlns="http://www.w3.org/2000/svg" version="1.0"><filter id="f1"><feGaussianBlur in="SourceGraphic" stdDeviation="0.000000000000000000000000001" /></filter><rect width="100%" height="100%" fill="lime"/><circle fill="red" r="98" cx="200" cy="100"/><circle fill="lime" r="100" cx="200" cy="100" filter="url(#f1)%22/%3E%3C/svg%3E 
```
It gives a red circle inside a green rectangle which is being cutout.



Ha! This is still valid when loading directly as an SVG file. Adding a test case for it. 

I will add a screenshot

[Karl Dubost]

Created attachment 466351 [details]
rendering in safari, firefox, chrome

Rendering in the latest versions of STP, nightly and canary as of today.