Re: Font fallback mechanism

[Fred Kiefer]

> I would like to suggest a fallback font mechanism in GNUstep.
>  Right now, user can specify the font they want to use
>  in .GNUstepDefault, and only one font can be specified.
>  But one font can't contain all the characters from English to Chinese.
>  As far as I know, WindowMaker and GTK use a fall-back mechanism
>  to solve this problem.
>  User can specify more than one font in the setting,
>  like NSFont = (Times, MingTi);
>  The program will try to use the first specified font,
>  and if the first specified font doesn't support the encoding,
>  it will try to use the second specified font, and so on.
>  That's the easy way to display multiple language at the same time,
>  and I guess the easy way to implement in GNUstep. 

I appreciate the idea behind this, we really need a better support for 
different scripts in GNUstep. What I doubt is, if the way you suggest to 
solve this would be possible to implement and if so, if it would help at 
all.

OpenStep has its own solution for the problem, but currently GNUstep 
does not implement it: Here the method fixFontAttributeInRange: on 
NSAttributedString is used to redefine the used font to one that offers 
the needed characters. So the easiest way to achive what you suggest, 
would be to implement this method. The order in which fonts are checked 
for the replacement would be defined by the preferredFontNames of 
NSFont, perhaps this would be the place where your font list could be used.
I don't know how MacOSX handles this, as the fix... methods seem to be 
gone there.

Cheers
Fred