[NTG-context] VORG and vmtx table in fontloader

Hironori KITAGAWA h_kitagawa2001 at yahoo.co.jp
Mon Jul 22 11:03:14 CEST 2019


Hello all,

It seems that ConTeXt's fontloader (hence luaotfload's fontloader) 
skips to load the VORG table and topSideBearing in the vmtx table
These informations are used to get the vertical origin of a glyph.

> readers.vorg = function(f,fontdata,specification)
>     reportskippedtable(f,fontdata,"vorg",specification.glyphs)
> end

> readers.vmtx = function(f,fontdata,specification)
> ...
>         for i=0,nofmetrics-1 do
>          ... 
>             if vheight ~= 0 and vheight ~= vdefault then
>                 glyph.vheight = vheight
>             end
>          -- if topsidebearing ~= 0 then
>          --     glyph.tsb = topsidebearing
>          -- end

I don't know whether vertical metrics are used in ConTeXt.
But, they will be useful for other packages (e.g., LuaTeX-ja)
to improve vertical typesetting.

Regards
Hironori KITAGAWA
<h_kitagawa2001 at yahoo.co.jp>


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