Re: Get and set pixel values

[Havoc Pennington <hp redhat com>]

Björne Lindberg <bjorne lindberg tfe umu se> writes:
>  
>
> I have loaded a pixmap image into a drawable area and now I want to rewrite it
> with some of the pixels moved from (xa.ya) to (xb, yb), but how can I get the
> pixel value at point (x,y) and how do I set the pixel value at the new
> (x1,y1)?
>
>  
>
> I need something like this:
>
>  
>
> setPixelValue(getPixelValue(x,y),x1,y1)
>
> and it would be nice if it's quite fast, gdk_draw_point() will probably be to
> slow.
>
>  
>
> Are there anyone who might have a solution for me?
>
>  

The only remotely fast way to do this is to gtk_image_get() part of
the pixmap, modify the image, then draw the image back; with the
rather nasty problem that pixels have a different size and format
according to display visual.

With gdk-pixbuf you can use gdk_pixbuf_get_from_drawable() instead and
modify the GdkPixbuf (a GdkPixbuf is essentially a GtkImage with a
nicer format).  For now this is a separate library from GTK but will
ship with GTK 2.0.

Havoc