Different vertical glyph positions between ot and ft font functions

[khaledhosny]

right (ot):

hb-view DejaVuSans.ttf "GgXx" --direction=t --font-funcs=ot

left (ft):

hb-view DejaVuSans.ttf "GgXx" --direction=t --font-funcs=ft

[behdad]

FT doesn't implement VORG. It should some day. HB too. But that only affects CFF.

For TrueType vertical, we should fetch tsb from glyf table and use it for to implement v_origin func. That's currently missing.

[behdad]

VORG is #544

[HinTak]

#1248 is not about glyph positioning, but font extents. FWIW. One of the values has a completely opposite sign!

[HinTak]

The font concerned - msmincho - does not have a VORG table. It has a vhea table.

[HinTak]

Also, my arriving at this issue is not that the two sets of functions behave differently, but that different set is the default, depending on how you open your file. hb-view defaults to the ft set, while the gobject interface defaults to the ot set.

[HinTak]

In the case of msmincho, the glyph positioning is identical (and uninteresting...). Here is the difference in the font extent functions - notice the clipping. (I have reversed the background/foreground color, but everything else is default). ft returns a width of 288, ot returns a width of 216.

[behdad]

FWIW. One of the values has a completely opposite sign!

You're amazing at writing useless bug reports. ;)

[HinTak]

FWIW, the descender changed sign from -36 to +36 (hence the 216 to 288 difference) between the ot/ft font funcs.

(1) writing/editing from mobile phone, don't always have all the details, (2) msmincho is common enough that it is easy for most people to see it themselves.

msmincho is perhaps also the first/most-used font that most non-tech people would try writing a vertical layout document in.

[behdad]

Still different. Reopening.