Re: gamegrid.el and some games

[Oliver Scholz]

Richard Stallman <address@hidden> writes:

>     I don't know anything about Emacs' internals. Does an Emacs that
>     supports images always support colours, too?
>
> Emacs always supports colors, but the display in use could be monochrome.
> Use display-color-p to test that.

Pardon my ignorance: what happens with colour images on monochrome
displays? Are they displayed in shades of gray if
`display-grayscale-p' returns nil?  If so, the conversion of XPM to
PPM would probably do for such displays.

Are there any displays for which `display-images-p' returns t, but
both `display-color-p' and `display-grayscale-p' return nil? Is it
necessary to make sure that gamegrid.el DTRT on such displays?

If not, I suggest to simply convert XPMs via some Lisp functions if
Emacs is compiled without XPM-support on the C-level. I have written a
prototype[1] for this. What do you think?

xpm.el
Description: application/emacs-lisp

    -- Oliver

PS: Could someone who has an Emacs compiled with image-support, but
without XPM-support check if the following gives a coloured image for
him or her, please?

(require 'gamegrid)

(insert-image 
 (xpm-convert-string gamegrid-xpm 
                     '((col1 . "Blue") 
                       (col2 . "Red") 
                       (col3 . "Green")) 
                     :ascent 'center))


Footnotes: 
[1]  I have not read the specification for the XPM-format, yet. (My
ghostscript is b0rked.) My knowledge of the format is based on a few
example XPMs.
Furthermore I am just an amateur. I would appreciate it, if an
experienced programmer could have a quick glance over my code and tell
me if the approach is clean/unclean/silly/sound.
And finally, if you like the idea, this should probably go into
images.el, not into gamegrid.el, and hook there into the functions to
create images.
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