Re: Grayscale visuals

[Owen Taylor <otaylor redhat com>]

Arthur Jerijian <lightmanaj@earthlink.net> writes:

> Hi all,
> 
> Do the mask, shift, and prec parameters (for red, green, and blue) exists in
> grayscale visuals? If not, then how can I convert back-and-forth
> between a GDK pixel and component RGB values in grayscale visuals?

The depth is the only interesting parameter for a static-gray visual
(or grayscale visual with a normal colormap) typically, converting
from the pixel value to RGB would look something like:

 r = pixel << (16 - visual->depth);
 g = pixel << (16 - visual->depth);
 b = pixel << (16 - visual->depth);

and the reverse something like:

 pixel = ((r + g + b) / 3) >> (16 - visual->depth);

Regards,
                                        Owen