RESOLVED INVALID261615
[Filters] Referenced SVG filters with outsets get clipped 
https://bugs.webkit.org/show_bug.cgi?id=261615
Summary [Filters] Referenced SVG filters with outsets get clipped
Said Abou-Hallawa
Reported 2023-09-15 12:01:50 PDT
1. Open the attached test case. 2. The green box has a css drop-shadow filter applied to it. 3. The red box has a css with a referenced SVG <feDropShadow> filter applied to it. 4. Notice the difference in drawing the referenced SVG <feDropShadow> filter. Result: The referenced SVG <feDropShadow> filter seems clipped. Expected: The display of the two filters in the test case should be identical.
Attachments
test case (697 bytes, text/html)
2023-09-15 12:02 PDT, Said Abou-Hallawa 		no flags
Details
test case 2 (968 bytes, text/html)
2023-09-15 12:07 PDT, Said Abou-Hallawa 		no flags
Details
test case 3 (968 bytes, text/html)
2023-09-15 12:14 PDT, Said Abou-Hallawa 		no flags
Details
work-around (1013 bytes, text/html)
2023-09-19 17:11 PDT, Said Abou-Hallawa 		no flags
Details
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.
Said Abou-Hallawa
Comment 1 2023-09-15 12:02:10 PDT
Created attachment 467688 [details] test case
Said Abou-Hallawa
Comment 2 2023-09-15 12:07:45 PDT
Created attachment 467689 [details] test case 2
Said Abou-Hallawa
Comment 3 2023-09-15 12:14:11 PDT
Created attachment 467690 [details] test case 3
Radar WebKit Bug Importer
Comment 4 2023-09-15 12:34:00 PDT
<rdar://problem/115567857>
Said Abou-Hallawa
Comment 5 2023-09-15 12:36:59 PDT
Pull request: https://github.com/WebKit/WebKit/pull/17822
Said Abou-Hallawa
Comment 6 2023-09-19 17:11:13 PDT
A workaround for this clipping is to set the geometry of the filter element to take into account the outsets of its effects. For example changing the <filter> tag in the above test case from <filter id="svgDropShadow"> to <filter id="svgDropShadow" x="-50%" y="-50%" width="200%" height="200%"> fixes the clipping. But it is sometimes hard to predict the exact outsets of the filter effects. For example the outsets of this effect is { 30, 30, 30, 30 } <feDropShadow dx="30" dy="30" stdDeviation="0"/> While the outsets of this effect is about { 50, 50, 50, 50 } <feDropShadow dx="30" dy="30" stdDeviation="10"/> Finding these values can be done by trial and error or by looking at the code and understanding how the outsets are calculated.
Said Abou-Hallawa
Comment 7 2023-09-19 17:11:43 PDT
Created attachment 467768 [details] work-around
Said Abou-Hallawa
Comment 8 2023-09-19 17:13:34 PDT
I am going to resolve this bug as "Invalid" since all browsers respect the geometry of the referenced SVG filter in drawing the CSS filter.
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