inserting images in light and dark background

inserting images in light and dark background

[Miguel Frasson]

Hi

I have a set of icon sized images in xpm format. They are grayscale, with
white background and black is the "foreground" color (gray in the middle).

They are very nice to insert in a buffer, but if one uses black
background (like me!!), they are terrible. I wnat to white a elisp program
to display them, no matter background.

The best solution would be able to display them in reverse-video if the
background is black. Is thee a way to do it?

[]'s

Miguel


-- 
Miguel Vinicius Santini Frasson
http://www.math.leidenuniv.nl/~frasson

Re: inserting images in light and dark background

[Oliver Scholz]

Miguel Frasson <frasson@enquist.math.leidenuniv.nl> writes:

> Hi
>
> I have a set of icon sized images in xpm format. They are grayscale, with
> white background and black is the "foreground" color (gray in the middle).
>
> They are very nice to insert in a buffer, but if one uses black
> background (like me!!), they are terrible. I wnat to white a elisp program
> to display them, no matter background.
>
> The best solution would be able to display them in reverse-video if the
> background is black. Is thee a way to do it?

I am not aware of any functionality like that. However, the XPM
format provides a means to change the colours of an image at
run-time. Take this example:


(defvar my-xpm "/* XPM */
static char * my_xpm[] = {
\"10 10 3 1\",
\". s back c White\",
\"o s medium c Grey50\",
\"# s fore c Black\",
\"....##....\",
\"..##..##..\",
\".#......#.\",
\"#...oo...#\",
\"#..oooo..#\",
\"#..oooo..#\",
\"#...oo...#\",
\".#......#.\",
\"..##..##..\",
\"....##....\"};")

In the colour specification the key-symbol "c" specifies the colour
to use on a colour display. The "s" symbol specifies a symbol to
reference the according pixels and assign a different colour to them
programmatically. This will insert the image with the colours
specified by "c":

(insert-image (create-image my-xpm 'xpm t))

But this will insert the image with different colours:

(insert-image (create-image my-xpm 'xpm t
			    :color-symbols '(("back" . "black")
					     ("medium" . "darkslateblue")
					     ("fore" . "white"))))


If you can't change the XPM images, then the best I can think of is to
make the background transparent:

(insert-image (create-image my-xpm 'xpm t
			    :mask '(heuristic t)))

Even if you can change the XPM files, it is probably a good idea
anyways to use a transparent background instead of white. Your users
could have a light grey background, for instance. Use the special
symbol "None" in the XPM file for this, e.g. in the example above
change ". s back c White", to ". s back c None".


    Oliver
--
4 Pluviôse an 212 de la Révolution
Liberté, Egalité, Fraternité!