Transparent pixmaps?

[johannes nada kth se (Johannes Keukelaar)]

Hello all,

I tried to post this earlier, but suspect that it didn't get through. I seem to 
get kicked off the mailing list every couple of days or so. *sigh* Anyway, if 
it didn't get through:

I'm working on an application that will visualize certain expensive-to-draw 
objects; these objects are nonrectangular, have a position and size and may 
overlap. Even worse (I would think) is that the objects may even have holes in 
them; just drawing a filled polygon and then filling in the holes again with 
the background color would not always work for overlapping objects.

For this reason and to speed up rendering, I've been looking at using partially 
transparent pixmaps. However, there doesn't seem to be a way to properly draw 
these on the screen. Given, e.g. a pixmap and a bitmap mask, how would I go 
about drawing those on the screen so that the transparency mask works? I've 
been unable to figure out a better way than to do this in a loop with 
GetPixel/PutPixel (or some such). Any hints?

Thanks,

Johannes.
--
There are two classes of people: Those who divide people into classes, and 
those who don't.

How do I connect to that real-life thing I keep hearing about?