W3C home > Mailing lists > Public > www-svg@w3.org > August 2012

SVG Compositing Details

From: Bob Holmes <rangsynth@gmail.com>
Date: Tue, 14 Aug 2012 14:22:05 +0200
Message-ID: <CAMvo67ZanmewyAy5TLH29dD-xFXMz2Lzh4gHRXhPtgKGn7Ne0w@mail.gmail.com>
To: Rik Cabanier <cabanier@gmail.com>
Cc: Nikos Andronikos <Nikos.Andronikos@cisra.canon.com.au>, www-svg@w3.org
Suggestions

A) In Section 1.2
While this specification provides the author the choice of many Porter
Duff compositing operators and many blending modes, the simple alpha
compositing model forced a single Porter Duff compositing operator and
a single blend mode.

While this specification provides the author the choice of many Porter
Duff compositing operators and many blending modes, the simple alpha
compositing model forced a single Porter Duff compositing operator and
a single blend mode, WHICH IS SPECIFICALLY SRCOVER COMPOSITE MODE AND
NORMAL BLEND MODE RESPECTIVELY.

More emphasis needs to be placed on this factor. Implementors with
decent design should not be concerned with simple alpha compositing or
the formula. Only the formula for SRCOVER and NORMAL blend mode
surely?(Because is same thing Yes?)

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B) Section 6.1.1
This is the default attribute which specifies no blending. The
blending formula simply select the source color.

SHOULD IT NOT SAY "SIMPLY SELECTS THE SOURCE COLOR"?

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C) 5.1.7. Destination In

NEED TO INSERT A LINE BREAK BEFORE THE ao
Fa = 0 Fb = s
    co = b x Cb x s o = b x s

SHOULD BE
Fa = 0 Fb = s
    co = b x Cb x s
    o = b x s

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D) Reference bitmaps
Would be nice to have reference bitmaps.

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E) Alpha Adjustment/Masking/Opacity
It would be nice if there was a section or some more emphasis as a
guide to implementors on the fact that any alpha adjustments can
simply be made before the blending function. Drawing to a layer with
some masks then works fine. Then drawing the layer to the background
using "srcover" composite mode allows the opacity and any further
masking to be applied just before the srcover and all works well.
Received on Tuesday, 14 August 2012 12:22:34 GMT

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