[CREATE] Color opacity

Chris Lilley chris at w3.org
Tue May 20 07:39:18 PDT 2008

On Tuesday, May 20, 2008, 4:26:50 PM, Olivier wrote:

OB> SVG Tiny 1.2
OB> <http://www.w3.org/TR/SVGMobile12/painting.html#SolidColorElement>
OB> gives an opacity argument to the solidColor element. What is the
OB> concrete signification of color opacity? An object can have an
OB> opacity level but giving that attribute to a color isn't it mixing concepts?

Any object can have a global opacity, yes.

It can also have a fill opacity, stroke opacity, and so on.

Consider an object which has a gradient fill; one stop is yellow at
full stop-opacity and one is red at 0.2 stop-opacity. (You could also add stroke
opacity, fill-opacity, or even global opacity, to the same object).

Now consider a gradient where both stops have the same color and same
opacity. (This is what people used to do to make a paaint server,
before we had a solidColor element). So its essentially a single stop
gradient; and it has a solid-opacity property analagous to the

 Chris Lilley                    mailto:chris at w3.org
 Interaction Domain Leader
 W3C Graphics Activity Lead
 Co-Chair, W3C Hypertext CG

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