[Freetype] face->max_advance_width and the FreeType backend for XFree86

[Juliusz Chroboczek]

Dear all,

Unlike the Type 1 backend, the FreeType backend doesn't provide
clients with an accurate average width.  What it does is to provide
accurate average width for monospaced fonts (obviously), and just give
half the maximum advance width for proportional fonts.

While this heuristic works reasonably well with TrueType fonts, it
gives rather bad results with Type 1 fonts.  As pointed out by James
Cloos, the resulting value is varies widely between Type 1 and
TrueType fonts.  Here are a few samples of the values provided by
FreeType:

TrueType fonts:

  Monotype Times New Roman: 2.0 em
  Monotype Arial: 2.0 em

Type 1 fonts:

  Monotype Times New Roman PSMT: 0.25 em
  Monotype Arial PSMT: 0.278 em

I'm wondering whether there's something wrong with FreeType, or
whether I should use a different value to base my heuristic on.  Any
suggestions welcome.

Thanks to all,

                                        Juliusz