Re: Styling vertical text, initial article and interactive tests

> On 26 May 2015, at 19:07, Richard Ishida <ishida@w3.org> wrote:
> 
> On 26/05/2015 17:55, cowan@ccil.org wrote:
>> Elizabeth J. Pyatt scripsit:
>> 
>>> Will this page be looking at the Irish Ogham as test cases?
>>> There are some archival projects on the Web where having accurate
>>> representation in a vertical format in Unicode could be beneficial.
>> 
>> Ogham is normally transcribed (or written on a MS ab origine) like
>> Latin: horizontal and left-to-right.  For that matter, when Latin
>> is inscribed on a monumental arch, it too is written bottom to top,
>> then horizontally, then top to bottom, with appropriate letter
>> rotation.
> 
> yes, that was my understanding too.  Not just on arches, but stone inscriptions too.  The present article will focus specifically on CJKM, though i suspect that one may be able to glean information on how to address Latin and Ogham verticality quite easily while reading it.
> 
> 
>> Richard:  It seems to me that the main use of sideways-left is when
>> you want non-vertical text to appear vertically bottom-up, as on the
>> spine of a German book, an arch as described above, or a caption
>> placed to the left of a table (often in a column that spans all the
>> rows).  A right-side caption, per contra, needs to be written
>> top-down and sideways-right.
> 
> yes, thanks, John. I don't really have any difficulty with the sideways-right and sideways-left values. It's just the alternative sideways value that i haven't yet fully understood the use case for.

The key is that text-orientation isn't used alone, but together with the writing-mode property.

If you're setting latin text on book spines or captions of the side of images or tables, you pick vertical-lr or vertical-rl as the value of writing-mode depending on which side of the figure you want your caption on or which way spines go in your country or which side of the arch you're on, and "text-orientation:sideways" automatically picks the right one between sideways-right and sideways-left to make the orientation of glyphs in a line match the stacking order of lines. Setting the text-orientation to "sideways" on the entire document for latin text (or any natively horizontal script) will give you the right thing. You could just used sideways-right and sideways-left explicitly, but you'd have to make sure to keep them in sync with vertical-lr and vertical-rl, which could be tedious and error prone.

For pieces of latin text in vertical CJK, sideways also computes to sideways-right since they use which use vertical-rl), and that's what you want, So latin-in-CJK, it doesn't matter if you specify sideways or sideways-right explicitly.

However, vertical Mongolian, which uses vertical-lr, also uses sideways-right for inline pieces of latin text, so it must be set explicitly to sideways-right.

There's one more use case for sideways-left I am aware of. RTL scripts such as Arabic or Hebrew, when embedded in vertical CJK text, are often set with sideways-right, so that the glyph orientation matches latin text. However, sometimes it is set with sideways-left. Doing so means that the CJK text and the RTL text both flow downwards, removing the need for bidi.

I hope that clears up the use cases for the various variants of sideways.

 - Florian

Received on Tuesday, 26 May 2015 19:59:22 UTC