[cairo] changing alpha in herds

Carl Worth cworth at cworth.org
Mon Nov 5 13:15:25 PST 2007

On Mon, 5 Nov 2007 22:50:36 +0200, Donn wrote:
> Hi again,
> In my random quest to draw things from a stack, I am wondering how best to
> tackle this:

Hi again, Donn,

I'm quite glad that so far your questions have fairly easy
answers. :-)

> I'm aiming for:
> <some voodoo alpha = 0.5>
> BigSquare.draw()
> <end voodoo>
> If that makes any sense :)

Yes, I think it does. Here's some voodoo that might be exactly what
you're looking for, (I'll write in C because I'm much less likely to
make it totally wrong than if I attempted python---hopefully you'll be
able to translate to python just fine---if you have any trouble just

	cairo_push_group (cr);
	draw (BigSquare);
	cairo_pop_group_to_source (cr);
	cairo_paint_with_alpha (cr, 0.5);

I hope that helps! If you need voodoo with different semantics, let us

And please feel free to add anything useful you learn to the cairo
website. The whole thing is a world-writable wiki, (small registration
step required first). For example, you might add things here:


Have fun with cairo!

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