- From: Rik Cabanier <cabanier@gmail.com>
- Date: Thu, 17 Nov 2011 21:10:48 -0800
- To: www-svg <www-svg@w3.org>, public-fx@w3.org
- Message-ID: <CAGN7qDBPJBmyAkJehKsNcSe+sy1n1V7nhdZNNRjrvDOyD01arg@mail.gmail.com>
Last week I sent out some ideas to update the SVG composting spec: http://www.w3.org/TR/SVGCompositing/. Some people suggested some improvements which I integrated. Here is the updated list of proposals: a. split up the spec in 2 sections: Porter-Duff & Blending. Porter-Duff are compositing primitives that describes how 2 images (src+dst) can be merged. Porter-Duff will continue to use the existing comp-op property. Blending describes how the top image will 'blend' with its underlying colors. The result of this is a new blended image. In the Adobe imaging model and the existing SVG compositing spec it is assumed that this blended image is composited with src-over. However, there are use cases where you might not want 'src-over'. To facilitate other composting operators, we will introduce a new keyword 'blend-mode'. b. simplify Porter-Duff -remove the clip-to-self property. The default behavior becomes 'clip-to-self: object'. c. complete blend modes - add the following missing blend modes: hue, saturation, color & luminosity - define 'normal' as the default blend mode d. update knockout - change the value to be more descriptive. The new value ('replace'/'preserve') is confusing. - provide a better description + correct the compositing formula - knockout will only affect groups that use the new 'blend-mode' operator e. update enable-background - remove the ability to set up x, y, width & height. - clarify the description and refer to the filters spec which already defines this parameter - replace the keyword with 'isolate' which is Adobe's equivalent. 'isolate: isolated' = 'enable-background: new'. Keep the existing parameter for backward compatibility. - Any comp-op apart from 'src-over' will establish a new stacking context. f. update all the formulas on the page - fix incorrect math - always do the math with pre-multiplied alpha. g. replace 'src'/'dst' in the spec with 'source'/'dest' Let me know if I missed something. Rik
Received on Friday, 18 November 2011 05:11:17 UTC