Re: How does one overlay one image on top of another ?

[Bob Murphy <bob murphy access-company com>]

> As an alternate, how might I generate a new pixbuf with the 2nd image's bits replacing the
> 1st image's bits at a specific location ? (I'm sure Gimp can do this, I'm just curious as
> to how it manages this...)

gdk_pixbuf_composite() does this. If the source pixbuf has an alpha 
channel, I believe it also does alpha-compositing on the colors. Here's 
a URL:
http://library.gnome.org/devel/gdk-pixbuf/stable/gdk-pixbuf-scaling.html#gdk-pixbuf-composite

If you want to do something fancier, you can analyze and/or modify the 
pixels comprising a GdkPixbuf. I've used this general approach to do 
some unusual things with raster images in pixbufs. For some simple 
sample code, take a look at example 1 in the following URL:
http://library.gnome.org/devel/gdk-pixbuf/stable/gdk-pixbuf-gdk-pixbuf.html

- Bob