Discussion:
Is it possible to choose rotational direction of vertical script if I want to force them to display horizontally?
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gfb hjjhjh
2016-01-25 16:23:52 UTC
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For instance, traditional Mongolian script write in vertical-lr mode (text
run vertically from top to bottom, first line start on left), if you use
css writing mode horizontal-tb (default) then you can force it horizontal
by rotating each line of the text by 90 degree anticlockwise, and the
resultant text would be ltr. However, I just read on a Chinese webpage
http://www.zhihu.com/question/30727581 which claim there're a "traditional
way" of writing Mongolian horizontally by rotating it 90 degree clockwise
(despite I am not sure about what kind of tradition the webpage is
referring to nor do i know is it legit.), is this achievable via css?
[The message is a repost from unicode mailing list as I have been pointed
out that the message suit this list better.]
fantasai
2016-01-26 07:16:51 UTC
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Post by gfb hjjhjh
For instance, traditional Mongolian script write in vertical-lr mode
(text run vertically from top to bottom, first line start on left),
if you use css writing mode horizontal-tb (default) then you can
force it horizontal by rotating each line of the text by 90 degree
anticlockwise, and the resultant text would be ltr. However, I just
read on a Chinese webpage http://www.zhihu.com/question/30727581
which claim there're a "traditional way" of writing Mongolian
horizontally by rotating it 90 degree clockwise (despite I am not
sure about what kind of tradition the webpage is referring to nor
do i know is it legit.), is this achievable via css?
I don't think this is possible in CSS, except for one-line text
(using 'transform' to flip it 180deg). As for tradition... I don't
think Mongolian has ever been written horizontally, traditionally.
It *was* however derived from an RTL script that was rotated 90deg
counter-clockwise to create Mongolian, so perhaps that is what they
are referring to.

~fantasai
gfb hjjhjh
2016-03-11 23:17:16 UTC
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Then is it possible to specify something in CSS writing mode level 3 to
change the line orientation?

The line orientation example in https://www.w3.org/TR/css3-writing-modes/
section 1 suggest that the right hand side is the up direction, however
according to what I've seen, it's true for the case when it's arranged
together with other horizontal-tb, ltr text, but I'm not sure about what'd
happen if those Mongolian text are placed within Arabic or Uyghur text, and
I think those who can write Mongolian text and are not influenced by
default direction in computer, nor modern ltr publication (which are all
ltr by default) might not consider right hand side as top.

The draft also stated that, for Mongolian text, "In horizontal text, they
are typeset in a 90° counter-clockwise rotation from this orientation."
which I am aware of it is the genral approach to handle Mongolian text in
horizontal emvironment nowadays but I don't know if it is 100% universal.

I think adding an attribute for these nonrotatable vertical text so that
user can choose if it want the left side or right side to be top/upright
when it's forced horizontal or when there's elements like overline and
underline might be a good idea? That's like specifying if you want your
English text to appear with the character "A"'s head pointing left or right
when it have to be rotated.

On the other hand, according to the draft, vertical 'mixed' typeset can't
be handled automatically for Ogham or Old Turkic as per UTR50 and css
writing mode and it suggest the use of sideways-lr as a workarpund but the
draft also say sideways-lr might be dropped. I wonder if it can be solved
by the attributes I have just suggested plus a new vertical-bt.

A bit more note: In the CR's Appendix A it said Old Turkic is ttb in its
Vertical direction but there's some other pages who say it is btt. Which
one is correct?

And actually in the current status what is the expected behaviour for
Mongolian text in vertical-tb, rtl environment? would they form in a wrong
way or force itself ltr?
Post by fantasai
Post by gfb hjjhjh
For instance, traditional Mongolian script write in vertical-lr mode
(text run vertically from top to bottom, first line start on left),
if you use css writing mode horizontal-tb (default) then you can
force it horizontal by rotating each line of the text by 90 degree
anticlockwise, and the resultant text would be ltr. However, I just
read on a Chinese webpage http://www.zhihu.com/question/30727581
which claim there're a "traditional way" of writing Mongolian
horizontally by rotating it 90 degree clockwise (despite I am not
sure about what kind of tradition the webpage is referring to nor
do i know is it legit.), is this achievable via css?
I don't think this is possible in CSS, except for one-line text
(using 'transform' to flip it 180deg). As for tradition... I don't
think Mongolian has ever been written horizontally, traditionally.
It *was* however derived from an RTL script that was rotated 90deg
counter-clockwise to create Mongolian, so perhaps that is what they
are referring to.
~fantasai
fantasai
2017-05-02 19:49:18 UTC
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Then is it possible to specify something in CSS writing mode level 3 to change the line orientation?
Only vertical-lr vs sideways-lr. There is no ability to change
the line orientation in horizontal text.
The line orientation example in https://www.w3.org/TR/css3-writing-modes/ section 1 suggest that the right hand side is the up
direction, however according to what I've seen, it's true for the case when it's arranged together with other horizontal-tb,
ltr text, but I'm not sure about what'd happen if those Mongolian text are placed within Arabic or Uyghur text, and I think
those who can write Mongolian text and are not influenced by default direction in computer, nor modern ltr publication (which
are all ltr by default) might not consider right hand side as top.
The draft also stated that, for Mongolian text, "In horizontal text, they are typeset in a 90° counter-clockwise rotation from
this orientation." which I am aware of it is the genral approach to handle Mongolian text in horizontal emvironment nowadays
but I don't know if it is 100% universal.
I think adding an attribute for these nonrotatable vertical text so that user can choose if it want the left side or right
side to be top/upright when it's forced horizontal or when there's elements like overline and underline might be a good idea?
That's like specifying if you want your English text to appear with the character "A"'s head pointing left or right when it
have to be rotated.
The case of clockwise-rotated Mongolian seems rather theoretical
at this point, and we don't add features for theoretical or archaic
use cases to CSS. It is not worth the implementation complexity.
If at some point this becomes a significant issue, we'll solve it
at that point.
A bit more note: In the CR's Appendix A it said Old Turkic is ttb
in its Vertical direction but there's some other pages who say it
is btt. Which one is correct?
I'm not a scholar of this language, but the evidence seems to point
to ttb-lr. A comparison of the Unicode code charts
http://www.unicode.org/charts/PDF/U10C00.pdf
and this inscription
Loading Image...
seems to indicate that it is written top to bottom, left to right.
(Note that Old Turkic is encoded as RTL, and the glyphs are rotated
counter-clockwise.) This is also backed up by the description in the
Unicode Standard:
http://www.unicode.org/versions/Unicode9.0.0/ch14.pdf
Additionally, we can see on the inscription that the bottom edge
is ragged and consistently ends in punctuation, which is a good
indication that it is the end, not the beginning, of the lines.
And actually in the current status what is the expected behaviour
for Mongolian text in vertical-tb, rtl environment? would they
form in a wrong way or force itself ltr?
There is no such thing as vertical-tb. In an rtl environment, the
Mongolian text will remain ltr, just like English and Chinese remain
ltr. Punctuation before and after the Mongolian text run, being
bidi-neutral, may become scrambled, however. You can look up the
Unicode Bidirectional Algorithm for more information on exactly how
this works.

~fantasai

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