Re: gamegrid.el and some games

[Oliver Scholz <alkibiades@gmx.de>]

Richard Stallman <rms@gnu.org> writes:

[black-and-white displays]

> It is possible that no such displays have been built in recent years.
> gamegrid.el should do SOME kind of Right Thing on those displays, but
> pretending they cannot draw images might be good enough.

I see.

[...]
> Converting XPM to PPM seems useful, because with this, we can arrange
> that Emacs can always display XPM format.  That makes the API specs
> simpler.  It would be nice if Emacs always used this conversion method
> when you try to display an XPM and the support is not built in.

O.K. I am working on it. 

> But why do you prefix this with "if not"?  I know very very little
> about these graphics formats, so it isn't obvious to me why this
> method would depend on being able to display more than just black and
> white.  Can you explain?

I know nothing about graphical black&white displays. I assume -- but
this is just a wild guess -- that on such a display _every_ coloured
pixel appears as black. I fear that this could lead to the end that
you have to play tetris or snake with black squares on a black
background, which makes it unnecessarily difficult.

So I agree that it's best and safest to use simple ascii-chars on
displays for which

(and (display-images-p) 
     (not (or (display-color-p)
              (display-grayscale-p))))

is t.

    -- Oliver

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