[css-writing-modes] Propose to weaken upright rendering of horizontal-only scripts

I’d like to propose to weaken spec words when rendering horizontal-only scripts in upright.

One in text-orientation: upright, the proposed change is from:
  characters from horizontal-only scripts are rendered upright
to:
  characters from horizontal-only scripts should be rendered upright

Then in the definition of “upright characters”[2], from:
  characters from horizontal cursive scripts (such as Arabic) are shaped in their isolated forms when typeset upright
to:
  characters from horizontal cursive scripts (such as Arabic) should be shaped in their isolated forms when typeset upright
or we could be more descriptive how we’d like to weaken.

The motivation is that I know little about if every single horizontal-only script can really render upright with this definition. I know there are people who knows it better than me, but a discussion of Jonathan and Behdad[3] indicated me that there are more we need to study, and I’m afraid to define it normatively with our current knowledge.

Further more, tests discovered that all browsers are not able to render some each own set of horizontal-only characters in upright. Fixing all of such issues would require broad knowledge of scripts in the world, which would require quite a work, and I think it is far beyond the basic vertical flow that better to defer.

Thoughts?

[1] http://dev.w3.org/csswg/css-writing-modes-3/#valdef-text-orientation-upright
[2] http://dev.w3.org/csswg/css-writing-modes-3/#typeset-upright
[3] http://lists.freedesktop.org/archives/harfbuzz/2015-April/004819.html

/koji

Received on Tuesday, 28 April 2015 18:02:33 UTC