gdk-pixbuf: partial image loading

[Nicolas George <nicolas george ens fr>]

Is it possible, with gdk pixbuf, tu partially load an image? By that, I
mean to get a pixbuf with only a sub-image or a shrinked image, without
loading all in memory. This would be really useful in order to load parts
of huges high resolution images, or scaled to fit on the screen, without
filling the memory.