Bug 6022 – SVG Filters do not support source images besides "sourceGraphic" and "sourceAlpha"

• Status: NEW
• Component: SVG

[Eric Seidel (no email)]

WebKit+SVG does not support any source images besides "sourceGraphic"
http://www.w3.org/TR/SVG/filters.html#CommonAttributes

We need to add support for:
SourceAlpha | BackgroundImage | BackgroundAlpha | FillPaint | StrokePaint | <filter-primitive-reference>

[Eric Seidel (no email)]

Sorry, we already (clearly!) support <filter-primitive-reference>, just not the rest.  None of these should 
be hard to do (with the possible exception of BackgroundImage/BackgroundAlpha.

FillPaint and StrokePaint should probably be implemented as CIImages with ImageProviders, so they can 
lazily create the bits as needed.

SourceAlpha is just SourceGraphic w/ an alpha-only filter applied.

All of these should be lazily generated on demand.

[Eric Seidel (no email)]

This is one of our two most basic SVG filter support bugs.  Shipping SVG with filter support would require solving this bug.  Adding SVGHitList keyword and bumping to p2.  I've included instructions above on how we might implement these.

[Alexander Kellett]

Created attachment 6036 [details]
testcase showing a related bug

i've attached a reduced testcase showing a bug in the current sourcealpha support

[Eric Seidel (no email)]

Oh, those above numbers were using 5 runs each, cached content.

[Eric Seidel (no email)]

We really need some test cases for these various modes.

[Dirk Schulze]

Created attachment 40584 [details]
Support for FilterEffect SourceAlpha

Support for FilterEffect SourceAlpha.

[Nikolas Zimmermann]

Comment on attachment 40584 [details]
Support for FilterEffect SourceAlpha

Looks great, r=me.

[Dirk Schulze]

Comment on attachment 40584 [details]
Support for FilterEffect SourceAlpha

Clering review flag. Landed in r49153.

[Andres Gomez Garcia]

Just adding a reference test, in case it is useful:
https://rawgit.com/tanty/design-hodgepodge/master/svg/filter/feBlend-backgroundimage-tests.html

Notice that for SVG 2 the "enable-background" is deprecated and the blending is governed by the isolation property:
http://dev.w3.org/fxtf/compositing-1/#isolation

Also, notice that, if I'm understanding correctly how the isolation property works, when using a SVG filter we shouldn't worry about what it is behind the SVG document since the filter makes a mandatory isolated group:
https://drafts.fxtf.org/compositing-1/#csscompositingrules_SVG

Similar issues from other web engines:
https://bugzilla.mozilla.org/show_bug.cgi?id=437554
https://code.google.com/p/chromium/issues/detail?id=137230
https://wpdev.uservoice.com/forums/257854-microsoft-edge-developer/suggestions/10238658-implement-backgroundimage-backgroundalpha-input-so

[Radar WebKit Bug Importer]

<rdar://problem/25719215>