Zoom/magnification of images in GDK

[<lindleyf cox net>]

I have a GUI which shows 640x480 video frames from a firewire camera. I've gotten a request to allow the user 
to zoom in on a particular part of the image if they choose; the camera doesn't have a zoom feature, so this 
wouldn't give any better resolution, but might make things easier to see anyway.

Right now, the image is being written to a GtkDrawingArea using gdk_draw_grey_image().

Now, I know how I could do this if I used gtkglext to get OpenGL in the picture, so I could throw the image 
into a texture and then render it at an arbitrary size. But I was wondering if there were any options built 
into GTK/GDK which would allow me to avoid the extra dependency?