On Mon, 12 Nov 2001, Thruput Ltd wrote:
> Dear Sirs,
>
> Has anybody written a X windows driver that converts 8 bit pseudocolor visuals into
>24 trucolor?
>
> This is the problem
>
> "what we need is having two different pseudo color 8 bits visuals, we
> will call "standard" and "underlay". in both visuals we have several
> windows and colormaps and we have a root window. But in the "standard"
> visual" we would have a special (fixed) transparency color index in each
> colormap, that allows to see the underlay visual windows below:
> for instance suppose i create window A in the underlay visual, and do some
> drawings inside : nothing appears on the screen.
> now i create another window B in the normal visual, and paint its
> background with the transparency color ; if part of the B window
> rectangle intersects the A window rectangle, i can see the drawings in the
> intersection.
> All of this is standard X11 behaviour.
>
> The colormaps in both visual can be changed in real time by the
> application. That's why the problem is complicated and prevents from using
> directly the hardware.
> But those changes are not done very often and we might accept a software
> palette in the two visuals, that maps pseudocolors to tru colors.
> that's why i'm confident a solution might exists with ony software changes
> in the driver or X server."
>
Doing this in software is a waste of time and the results would
be too slow to be usable. XFree86 supports simultaneous depth 8 and
24 visuals on hardware that supports it, that is Matrox and 3Dlabs
hardware. I think transparency key emulation on hardware that doesn't
do it is a bad idea.
Mark.
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