[Cairo] Cairo and 1bpp Bitmaps

[Keith Packard]

Around 9 o'clock on Nov 13, Christof Petig wrote:

> > If I clear the 
> > image with the cairo_fill, the hole image will be black....
> 
> I would expect to need to set the fill color to white first.

Ah, there's a good source of confusion -- A1 format is not black/white, 
it's just the alpha channel with no color associated at all.  Cairo has no 
1bpp surface that holds color at this point.

-keith