Virtual Fonts & "FTL", was Re: Merging TTF files?

[Terry Hancock]

Hi. Thanks for the reply!

Antoine Leca wrote:
> Terry Hancock wrote:
> > It seems there are a lot of TrueType fonts in the world,
> > but very few which are reasonably complete (or at least
> > have the glyphs I wanted).
> > [...]
> > An obviously desireable solution would be to find all
> > the appropriate fonts and use them together
> 
> Correct. This solution is usually known as "virtual font".

Okay, now I have a name for it -- that's usually good. :)
>From your further comments, I gather you think this is
the "right" solution to my problem.

> > Since Yudit uses FreeType as the font server I assume
> > that any limitations it has in this regard are probably
> > inherent in FreeType (which is why I'm writing here).
> 
> You are correct that FreeType currently lack the feature
> of virtualization, which conceptualy stands one level higher
> than the one FreeType intends to target.
> 
> Perhaps another feature for FTL ?
                              ^^^
I don't know what that is.  Couldn't find it on the web page.
"Free Type Layout", maybe?

> > 1) Load more than one TrueType font at a time -- i.e.
> > overload them successively, leaving unassigned characters
> > as they were?
> 
> That is a framework of a possible solution. I shall let
> David T. or Werner comment on this.
> 
> This certainly goes quite beyond what is currently
> implementated, so this is not straightforward. However,
> I do not know enough of the internals of FT2 to know
> if it is easy or not.

Another question would be whether this should perhaps
be handled by the application.  Yudit, as I said, appears
to do this with X11 fonts.  If the interface to FreeType
is similar enough, maybe the easiest solution would be
to modify the Yudit source.

In either case, one would have to sense when the font
had "given up" and returned a default character, instead
of a correctly formatted character (it'd be nice if
the FreeType API would let you figure this out).  Or 
else, one could simply define ranges for each font 
(i.e. don't overload, just use an outside code page 
mapping file to tell which ranges come from which font).

Or maybe this should be a thin layer between FreeType
and the application -- i.e. just capture requests
and remap them to the appropriate font via FreeType?
This would seem to favor the code page tables approach.

The point is, I'm willing to make a contribution to
fix "my personal itch" on this, but I'd like to find the
right leverage point to do it.  Also the point where
it would be most helpful to others as well as me (no
point in wasting effort). Maybe I need to read the API
docs for FreeType?

Thanks for the comments!

-- 
Terry Hancock
address@hidden