Using fbBlt() for printing black text with a transparent background

[Adam Jackson]

On Sunday 05 March 2006 23:32, kartikay malhotra wrote:
> Dear all
>
> I wish to print text as images using fbBlt() (Xserver). I've been able to
> do so with some success. I am able to produce black text on a white
> background. However, I wish to retain the background (grey, blue, or any
> image). Kindly tell me:

Assuming you want black text:

> 1. How to fill the buffer to get a transparent background.

White.

> 2. What values to choose for "alu" & "pm" in fbBlt()

GXand, and FB_ALLONES.

More generally, the planemask (pm) defines the bits within each pixel on which 
the raster operation defined by alu will operate.  ANDing white (all 1 bits) 
with any color will leave the original color in place; ANDing black (all 0 
bits) with any color will yield black.

You may, of course, be solving this problem at entirely the wrong level.

- ajax
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