- From: Alex Danilo <alex@pagefire.com>
- Date: Wed, 14 Apr 2010 15:53:57 +1000
- To: Dirk Schulze <vbs85@gmx.de>
- Cc: www-svg@w3.org
Hi, There are very good reasons why it is defined the way it is. Many more than I can put into an email. Basically the compositing operator is a property of an object, not 'glue' to join 2 objects together. We implemented it as you suggest back around 2003 or so and it doesn't work for the Porter-Duff operators proerly especially when combined with background-enable='accumulate'. Anthony may want to make some more comments. But the basic one is that it doesn't work properly if you try to represent compositing as nodes in the tree - which is effectively what you suggest. Adobe's ASV3 has compositing as a property on objects, via the adobe-blending-mode property. Illustrator will geberate that rather than use filters. Compositing can be achieved without using an intermediate store which I don't think you can expect when using a filter primitive. Alex --Original Message--: >Hi, > >I have a question to SVG Compositing >(http://www.w3.org/TR/2009/WD-SVGCompositing-20090430). Maybe it's to >late to make bigger changes on the Spec anyway, but wouldn't it be >easier to understand compositing by adding a new tag like <composite>? > >This tag could have attributes 'source', 'destination', 'operater' and >other attributes depending on the operator. The handling would be >simular to feComposite >(http://www.w3.org/TR/SVG11/filters.html#feComposite). > >Short example: ><svg> ><defs> > <rect id="rect" width="100" height="100" /> > <circle id="circle" r="50" cx="120" cy="120" /> ></defs> > ><composite source="url(#rect)" destination="url(#circle)" >operator="src-in" /> ></svg> > >Of course it should be possible to cascade the composite effects. >This is just a design proposal. It's hard to find examples for the use >of enable-background in the web (beside the wrong test in the test >suite: >http://dev.w3.org/SVG/profiles/1.1F2/test/svg/filters-blend-01-b.svg). >And I don't believe that it will be used more frequently for SVG 2.0 - >with or without Compositing. > >Dirk > > >
Received on Wednesday, 14 April 2010 15:54:28 UTC