Re: Dynamic Line Art - Clear action

Andreas Kraft (kraft@fokus.gmd.de)
Wed, 24 Jun 1998 16:54:54 +0200 ((MEZ) - Mitteleurop. Sommerzeit)

Dear colleagues,

On Wed, 24 Jun 1998, Emmanuel BEUQUE wrote:

> >What happens if this colour is not 100 per cent opaque? If you have
> >drawn anything in the object before the clear does this remain visible
> >through the semi transparent fill, or is anything drawn before the fill
> >supposed to quietly disappear so the transparency is onto the object
> >below the DLA object? One answer fits with the concept of "clear" and
> >the other with "fills the bounding box..."
>
> Andreas has already given the answer but there is a confusion here I think.
> What do you mean by "100 per cent opaque" ?
> There is a "Transparency" attribute for Bitmap class but it doesn't apply
> to LineArt one so that a lineArt color is always 100% opaque IMHO.

Yes, but an application domain can define a colour scheme where the three
basic colours plus a transparency factor are encoded in a single string
or number. This ways you have a transparency without support by the
MHEG-5 object.

> Regarding the OriginalRefFillColour, it is said to be transparent if not
> encoded. Consequently, if you use the Clear action, you fill or set each
> pixel of the DynamicLineArt with a transparent color i.e. the
> DynamicLineArt becomes completely transparent.

Right. But if you draw a non-transparent rectangle with another colour you
end up with a rectangle on a transparent DLA object...

Best regards,

Andreas

--
  o  _     Andreas Kraft
 (\_|_)      GMD FOKUS, kraft@fokus.gmd.de, +49 30 3463-7232
 T> ] [        The sky is the limit