The short story is, you can not. The glyphs of a digital typeface - a font as one Canadian prefers to name it - are nothing but vector(s) that can only be reproduced in one color as set by the application to use that digital typeface. In the case of an outline/hollow one thus only the vectors show. The rest is the background color, which is the 'inside' and the 'outside' of the outline/hollow one.
The long story is, yes it can be done but it makes typing extremely complicated as you would need both the outline glyphs and the inside of the outline glyphs is one and the same file and then have to change color for each subsequent character. Has been done. Madame is a nice example. But imho only usable for freaks.
Imagine this, without the spaces left and right of the = : [color = red]A[/color][color = green]a [/color] (which would be the filling of the outline A set at a negative position to fill the outline) to produce an A with an red outline and a green inline on a given background color. Sure no problem for one or two words. But imagine a 1000 letters text ... Brrrrrr
Edited 2 times. Last edit on Mar 23, 2013 at 22:40 by koeiekat
@ Sweetface, yes.
@ Claude, OP asked how to make a font that does this by itself. So without the use of a drawing application.
... as I said ... can be done but - imho - not very usable ... as Madame to name just one of other examples.
All times are CEST. The time is now 15:48