Re: char-displayable-p issue

[Jason Rumney <jasonr@gnu.org>]

Michael Mauger <mmaug@yahoo.com> writes:

> 3. Modify `x_to_w32_font' to handle the forms:
>    -FOUNDRY-*-REGISTRY-ENCODING
>    -*-REGISTRY-ENCODING
> 
>    The code in this routine is a little fragile.  There are many
>    special cases handled implicitly without explicit acknowledgement
>    that they are there.  

> I see option 3 as the ideal, and I will start to work on it. 

Thank you. I have tweaked that bit of code many times now to fix
bugs like this, it could do with a fresh set of eyes. Please document
any implicit special cases that you find.

> One other issue: Kenichi Handa said that the car of font-pattern
> could be one of "FOUNDRY-FAMILY", "*FAMILY", or "FOUNDRY*", in
> addition to nil.  My solution would not handle the "*FAMILY" form
> unless it is really sent as "*-FAMILY".  The Windows code does
> not handle partial wildcards in the font pattern.

I recently changed the font selection code in the emacs-unicode-2
branch to fix the same problem in charset and encoding fields. The
approach I took is to treat partial wildcards as full wildcards in
x_to_w32_charset, and to do more thorough comparisons in
enum_font_cb2.

> Trying to accommodate the partial wildcards in `x_to_w32_font' may
> break other usages.

That is my experience with trying to do anything in x_to_w32_font. It
is not an easy piece of code to get "right". That is why I have not
rushed into merging the changes I made to get emacs-unicode-2 to work
back into HEAD.