get_from_drawable for bitmaps

[Havoc Pennington <hp redhat com>]

Hi,

This patch allows gdk_pixbuf_get_from_image/get_from_drawable to be
called with no colormap if the source drawable is a bitmap. It then
fills in the pixbuf with opaque white for on bits and transparent
black for off bits.

Also, it fixes some bugs in the old one-bit visual, I hope.

Not sure about one change; I removed:

  data = srow[xx >> 3] >> (7 - (xx & 7)) & 1;

replaced with:

  data = srow[xx >> 3] & (image->byte_order == GDK_MSB_FIRST ?
                                  (0x80 >> (xx & 7)) :
                                  (1 << (xx & 7)));

The existing code doesn't seem to work, I didn't really unpack it
enough to see why.

Can image->byte_order ever be different from current CPU order?
XGetPixel() in Xlib uses the field in the image, but current
get_from_drawable() code just does a compile time thing (I think), so
maybe I could write:

#ifdef LITTLE
  data = srow[xx >> 3] & (1 << (xx & 7));
#else
  data = srow[xx >> 3] & (0x80 >> (xx & 7));
#endif

However, gdk_image_new_bitmap() for example seems to always use
MSBFirst, so that's at least one way to get MSBFirst on any CPU,
right?

I really, really hate this bitshifting graphics code hell. ;-)

Havoc