[ft] Vertical layout

[Sergey Tolstov]

Hello,

In what state is FT support for vertical glyph metrics?

I am encountering problem with vertical glyph metrics, when they are
present in a font file. I get a huge number for the linearVertAdvance,
other values look fine, because of that, glyphs are not generated. I
need advance value in design units for WYSIWYG.

While debugging, I found:
In the ttgload.c, line 1768, subtraction is incorrect
        advance_height = (FT_UShort)( loader->pp4.y - loader->pp3.y );
should be, according to earlier calculations
        advance_height = (FT_UShort)( loader->pp3.y - loader->pp4.y );

Even with that fix, linearVertAdvance is calculated incorrectly. (Should
they use loader->vadvance instead?)

I see the problem, when I try to layout a string of Japanese text using
SimSun.ttf. It looks ok with Arial Unicode MS, but that font does not
have vertical metrics.

Version: 2.1.10

Thank you,
Sergey