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Re: [css-masking] multiple mask layers and mask-composite

From: fantasai <fantasai.lists@inkedblade.net>
Date: Wed, 05 Mar 2014 00:36:53 -0800
Message-ID: <5316E225.8040003@inkedblade.net>
To: www-style@w3.org
On 03/04/2014 12:54 AM, Dirk Schulze wrote:
> Hi all,
> We removed multiple mask layers from the CSS Masking spec[1]. We could not
> reach consensus on how to composite the different mask layers. [...]
> I would like to propose adding layered masks back to level 1 [by] adding
>  a new mask longhand property: mask-composite.
> Name: mask-composite
> Value: <composite-operator>#
> <composite-operator> = clear | copy | source-over | source-in | source-out | source-atop | destination-over | destination-in | destination-out | destination-atop | xor

I think this is an interesting idea worth exploring, and wouldn't mind
exploring it for L1.

Are there ways to make these values (or at least, the commonly-used ones)
more obvious? Not being a graphics person, I can't tell at all what they

I vaguely remember the problem being something about choosing between
   - each layer acts individually as a mask over all the layers+content
     before it
   - composite all the mask images, then use that as a mask
and then the possibility of grouping certain combinations of images
rather than all or none. Does your proposal address that in a reasonable

Received on Wednesday, 5 March 2014 08:37:20 UTC

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