[MPEG-OTSPEC] Vertical Writing: Character Orientations are Sometimes Uncontrollable

[梁海 Liang Hai]

The “compliance” talked about in the slides sounds a bit misguided.

The behavior specified by UAX #50 is a decent low-level default at most, and can’t address all the use cases. Therefore fonts naturally need to be diverse and address the flexibility required by typography.

The architectural problem is that, layout engines assume a predefined rotation property (based on UAX #50 or not) for characters, and there’s no reliable way to override that. The boundaries between rotated and upright runs even makes OTL a non-starter.

Therefore we need to define and implement a mechanism that allows layout engines to resolve a glyph’s rotation property based on both a predefined dataset *and* the current font’s overriding.

Best,
梁海 Liang Hai
https://lianghai.github.io

> On Aug 6, 2020, at 07:37, MURATA Makoto <eb2m-mrt at asahi-net.or.jp> wrote:
> 
> Folks,
> 
> This presentation explains typical problems around interactions 
> of fonts and vertical writing.
> 
> https://1drv.ms/p/s!An5Z79wj5AZBgsdN2pd2XmS08WslZA?e=UM5O6K <https://1drv.ms/p/s!An5Z79wj5AZBgsdN2pd2XmS08WslZA?e=UM5O6K>
> 
> Japanese publishers are forced to use rasterized text, which hampers 
> accessibility.  I hope that the activities planned here help to make 
> things better.
> 
> -- 
> Regards,
> Makoto
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