RE: A CGM Question: handling transparency

[Lofton Henderson <lofton@rockynet.com>]

Hi Benoit,
Hi Benoit,

At 12:16 PM 8/28/03 -0400, Benoit Bezaire
wrote:

[...]

SVG 1.0 ... what is the background?  I.e., if you just have a simple file, <svg>...blah...blah...</svg>, what is the "...blah...blah..." drawn on or over?  You are much more involved with this than I, and I'm drawing a blank on the answer.  Is it well defined in the SVG 1.0 standard, or undefined (i.e., "nothing", transparent), or viewer-dependent?

[Benoit Bezaire] Yes, it is well defined.  A canvas in SVG 1.0/1.0 is always initialized to transparent black.  You can find more info at:

http://www.w3.org/TR/SVG11/render.html#Grouping

http://www.w3.org/TR/SVG11/render.html#Elements

 

Thanks, that's the bit that I couldn't remember.

The WebCGM solution that I proposed earlier achieves that same effect -- choose the RGB-alpha colour model, and set BACKGROUND COLOUR to (0,0,0,0).

Cheers,
-Lofton.