[tex-live] Fontconfig for XeTeX versus regular fontconfig

[Jonathan Kew]

On 28 Oct 2011, at 11:08, Dr. Werner Fink wrote:
> 
> Reading the source code of web2c/xetexdir/XeTeXFontMgr_FC.cpp for
> xetex and xdvipdfmx/src/fontmap.c and a short comparision by testing
> leads me to the conclusion that XeTeXFontMgr_FC.cpp should be
> redesigned.  This because it reads in *all* fonts (very slow)
> and holds it in its own memory based cache ...

This is necessary to fully support xetex's font management - e.g., IIRC fontconfig patterns do not provide optical-size support. (Performance could be improved by caching details across runs, and just fstat'ing the files to check if they've changed, but simply using Fc patterns and relying on the Fc cache is not sufficient.)

> whereas fontmap.c
> simply uses the search options for font patterns to load *one*
> font at the time it is required.

So the problem is that what gets passed (via xdv) from xetex to xdvipdfmx is not precise enough to guarantee that this will locate the same font that xetex was using. Making xetex embed the font file path (and face index) in the xdv instead would resolve this.

JK