drawing image from a buffer using gdk_draw_image

[Patrick Sung <phsung ualberta ca>]

Hi,

I have been trying to draw an image (16-bit color) to a 16-bit color 
system, using a call like this:

GdkImage *img = gdk_image_new (GDK_IMAGE_FASTEST, gdk_visual_get_system 
(), 640, 482);

img->depth = 16;
img->byte_order = GDK_MSB_FIRST;
img->bpp = 2;
img->bpl = 640*2;
img->mem = buf;   /* buf is the pointer to the 16-bit colored data */

gdk_draw_image (some_d_area, gc, img, 0, 0, 0, 0, 640, 482);

however i got a black image.  The drawing area is created using 
gtk_drawing_area_new().

Do I have to do something extra before I call gdk_draw_image().  I tried 
to look into gdkrgb and see how it calls gdk_draw_image for 24/32 bit 
color image, but it is too complicate for me right now, and I don't have 
a good understanding of gdk_visual and gdk_colormap yet.

Regards,
Patrick