[Bug 21610] New: drop-shadow with support for inset shadow

https://www.w3.org/Bugs/Public/show_bug.cgi?id=21610

            Bug ID: 21610
           Summary: drop-shadow with support for inset shadow
    Classification: Unclassified
           Product: CSS
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Filter Effects
          Assignee: dino@apple.com
          Reporter: dschulze@adobe.com
        QA Contact: public-css-bugzilla@w3.org
                CC: cmarrin@apple.com, eoconnor@apple.com, smfr@me.com

Currently the drop-shadow shorthand filter does not support inset shadows and
the inset keyword (in comparison to box-shadow for instance). I wonder if this
could be added to the spec and would like to hear implementers input.

Most shorthands have the advantage that they can easily be HW accelerated. This
already seems not always be the case for drop-shadow on some platforms.
However,  I do not think that it is harder to implement inset shadow, even if
it will be of course slower than other filters.

Here is a short example how to use inset shadows with SVG Filters today[1]:

        <filter id="innershadow" x0="-50%" y0="-50%" width="200%"
height="200%">
            <feGaussianBlur in="SourceAlpha" stdDeviation="2" result="blur"/>
            <feOffset dy="3" dx="3"/>
            <feComposite in2="SourceAlpha" operator="arithmetic"
                    k2="-1" k3="1" result="shadowDiff"/>
            <feFlood flood-color="black" flood-opacity="1"/>
            <feComposite in2="shadowDiff" operator="in"/>
            <feComposite in2="SourceGraphic" operator="over"/>
        </filter>

Implementations could replace the inset shadow in the CSS string with an
equivalent filter chain as above.

[1] http://ledrug.wordpress.com/2010/09/30/learning-svg-lesson-2/

from http://lists.w3.org/Archives/Public/public-fx/2013JanMar/0262.html

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Received on Sunday, 7 April 2013 19:11:55 UTC