Re: mono, gray and index configs

Geert Uytterhoeven wrote:

On Thu, 11 Aug 2005, Antonino Daplas wrote:

quoted

On 8/11/05, Geert Uytterhoeven [off-list ref] wrote:

quoted

On Thu, 11 Aug 2005, Antonino A. Daplas wrote:

quoted

that all the lengths = 1 and offsets = 0.  Currently, we have no way to
specifically request for mono01, mono10, or 1-bit pseudocolor. Just check
for fix->visual afterwards.

For mono01 or mono10, if the visual is pseudocolor, just set the colormap to
black/white or white/black.

I don't know. If I can change the colormap, I would  advertise this as
1-bit pseudocolor, not monochrome.  Otherwise, why differentiate
between mono01 and mono10 if I can control what color is 0 and what
color is 1.  I think the closest definition of monochrome is 1-bit
static pseudocolor.  And we just have mono01 and mono10 to advertise
how hardware treats 0/1 (background/foreground or reverse).

Yes, for advertisement, that's true (cfr. amifb with bpp = 1, which is
pseudocolor).

Ok.

But when the app needs monochrome, it can ask for 1 bpp. If it returns a mono
visual, fine. If it returns a pseudocolor visual, set the colormap to
black/white.

quoted

I have a few things that are still not clear to me.  If I understand
it correctly, monochrome means 2 colors regardless of the bit depth. 

Monochrome means 2 colors, which are black and white (or white and black). If
the colors are different, it's (static) pseudocolor.

In fact monochrome is a special case of static pseudocolor.

Ok.

quoted

So it's possible, for example, to have 8-bit monochrome that has only
two colors, ie 0x00 and 0xff.   If this was 8-bit static pseudocolor,

Yes, cfr. old HP9000/300 graphics hardware.

Hmm.  Yes, there's a bug in fbdev then with regards to this hardware.

quoted

then it has 256 different colors.

Yes.

quoted

(Depending on how correct I am with the interpretation, there might be
some bugs in fbdev on how it determines the color depth. No one is
complaining yet though, so greater than 1-bit monochrome is probably
rare if not nonexistent.)

There definitely are bugs w.r.t. this, especially in the 2.4 logo code ;-)

Yes, I would agree.  Do you know of any outstanding bugs on color handling
in 2.6 code, especially for hardware with bitdepths < 8? I would like to
fix them.

Tony


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