Bug 196761

Summary:	Unprefixed clip-path present in computed stye (for SVG), but doesn't work on CSS boxes
Product:	WebKit	Reporter:	Jack Doyle <jack>
Component:	CSS	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	bfulgham, krit, simon.fraser, webkit-bug-importer, zalan
Priority:	P2	Keywords:	InRadar
Version:	Safari 12
Hardware:	Unspecified
OS:	Unspecified
See Also:	https://bugs.webkit.org/show_bug.cgi?id=187888
Bug Depends on:
Bug Blocks:	126207

Description Jack Doyle 2019-04-09 21:29:37 PDT

The JavaScript element.style.clipPath is present (returns "" instead of undefined), indicating a prefix is NOT needed. However, if you apply a clipPath (without the -webkit- prefix), it doesn't work! Here's a reduced test case:

https://codepen.io/GreenSock/pen/4ec363d7fca960b501b390634fdf2e39?editors=0010

For a non-valid property (like element.style.bogus), undefined is returned (correct). So this clipPath behavior is very confusing (and I'd say clearly a bug). The element.style.clipPath test is passing, but functionality fails. It should either be fully functional in unprefixed form, or element.style.clipPath should return undefined.

Possibly a related thread: https://bugs.webkit.org/show_bug.cgi?id=187888

Comment 1 Radar WebKit Bug Importer 2019-04-09 23:24:46 PDT

<rdar://problem/49764514>

Comment 2 Simon Fraser (smfr) 2019-04-10 09:27:24 PDT

clip-path is present in computed style because it's present for SVG in the non-prefixed form.

Comment 3 Jack Doyle 2019-04-10 10:19:39 PDT

This seems like non-standard behavior. My demo isn't using an SVG element. Shouldn't it be returning undefined (indicating it's not supported on that element)? Of course ideally it would actually just work unprefixed.

Comment 4 Dirk Schulze 2019-10-04 10:47:21 PDT

We did not unprefix clip-path yet (though there is a patch for doing so). Sadly that means that both properties behave like 2 different properties as long as we did not unprefix (and alias the prefixed version) of Clip-path.

Comment 5 Dirk Schulze 2019-10-04 10:50:05 PDT

(In reply to Dirk Schulze from comment #4)
> We did not unprefix clip-path yet (though there is a patch for doing so).
> Sadly that means that both properties behave like 2 different properties as
> long as we did not unprefix (and alias the prefixed version) of Clip-path.

Forgot the background: clip-path was introduced by and for SVG. -WebKit-Clip-path for HTML first. So those properties currently ARE 2 different properties. When unprefixing we plan to make them one. Foundation is there already. You should be able to find the bug that is duplicated by this bug by searching for clip-path.