[ft-devel] ascender = descender = linegap = 0

[Werner LEMBERG]

I have an old font called `Agenda-MediumItalic.ttf' (probably from
1993) which has very strange `hhea' entries:

    <ascent value="0"/>
    <descent value="0"/>
    <lineGap value="0"/>

Additionally, it has an `OS/2' table, version 0 -- something which
Windows doesn't accept IIRC -- so it seems that this font is from/for
the Mac.  On the other hand, it has valid entries in `OS/2':

    <sTypoAscender value="712"/>
    <sTypoDescender value="-231"/>
    <sTypoLineGap value="71"/>
    <usWinAscent value="930"/>
    <usWinDescent value="238"/>

Currently, FreeType only uses the `hhea' table entries to compute the
`ascender', `descender', and `height' fields in `FT_Face' which means
that you get unusable values for this font.  What do you think about
providing a fall-back, say:

  if ascent == 0 && descent == 0
    use sTypoAscender and sTypoDescender
  endif

  if lineGap == 0
    use TypoLineGap
  endif

Do you have a better idea?  Shall I take care of this situation at
all?


    Werner