A bitmap is a two-color image where each bit in the image determines which of two specified colors appears on the screen.
The X Window interface requires support for both opaque and transparent bitmaps. X requires that, after each bit is expanded to a full pixel depth, the raster op mix (alu) occur with the destination pixel and that the hardware planemask be applied to the result when the destination pixel is written.
Most recent graphics chips
can achieve all these tasks.
Exceptions to this are
the Weitek P9000 that cannot apply
a raster operation to a transparent expanded pixel
and the Cirrus GD5426 which does not support a planemask.
The NFB interface supports the following routines to manipulate bitmaps:
|DrawMonoImage(D3nfb)||draws transparent bitmaps|
|DrawOpaqueMonoImage(D3nfb)||draws opaque expanded bitmaps|