[gtkada] Getting the color of one point ?

[Emmanuel Briot]

Jeremy Berthet wrote:
> I'm actually using a gdk_pixmap to draw on and a gtk_drawing_area to
> render it.
> 
> I have been looking, without any success, for a method to obtain the
> color of one point (pixel) at a specific position either on the pixmap
> or the drawing area.


I don't think you can do that with a gtk_drawing_area. This is a 
server-side pixmap (like a Gdk_Pixmap, in fact), and requesting the 
color of one pixel requires a round-trip to the server.
Have a look at either Gdk_Image/Gtk_Image, which is a client_side 
drawing area, or even a a Gdk_Pixbuf/Gdk_RGB, which seems to be what 
gtk+ itself uses when you load a jpg file for instance.
I don't have much on the technical details, though, so you should also 
investigate the C toolkit and mailing list and see how people do this in 
C. The mapping in Ada should be pretty straightforward after that.

regards,
Emmanuel