Good gtk object to make a captcha

["Tony B" <pktux86 gmail com>]

Hi,

I'm working in the idea to make a captcha (system generating picts containing text you should type to prove you're not a bot...) using GTK+ 2 and I'm seeking the right object to create an image from scratch and then saving it in a file.

I had a look in the tutorial and in the ref manual and 3 objects seems to be ok: gtk drawing_area, gtk_image, and Gdk Pixbuf.

I don't know really how I should make the choice (and I may forget another object I didn't see...).

What I have to do with the object is:
  * creating a pict with an uniform background
  * having the ability to do standard operations (points, polygons, etc...)
  * having the ability to read a pixel
  * having the ability to display text with a choosen font and size
  * being able to save the final image...
  * the rest to produce a good (I hope) captcha would be my work...

Has anybody any reasons for a choice or a pointer to relevant docs to make the choice?

Tony