On 23/03/2004 18:09, Thomas Kuehne wrote:
Am Mittwoch 24 März 2004 00:09 schrieb Asmus Freytag:
Is somebody already using a PUA assignment for vertical text
direction controls?
I think the idea was that these don't belong in plain text.
Markup languages have had vertical layout controls forever.
The problem arose at very resource limited devices, thus no HTML nor
RTF etc.. In fact there is no higher level protocol other than plain
strings/text.
While crawling through the Pango and SilGraphite rendering engines I
noticed that they provide(or are planning to) an interface for
vertical text.
For CJK, old European in-scripts and especially Egyptian hieroglyphs
it would be good to have a common control set - otherwise plain text
can't be used for data exchange.
Thomas Kuehne
It seems strangely inconsistent to me that Unicode has detailed controls
for horizontal layout direction and the complex bidi algorithm, but has
nothing for vertical layout. I can force Latin text to be rendered right
to left or Hebrew left to right (although such overrides are hardly
plain text issues), but there is no way I can select vertical layout
even for languages in which that is a normal way of writing. We already
have U+202A LEFT-TO-RIGHT EMBEDDING and U+202B RIGHT-TO-LEFT EMBEDDING.
It would be easy to define new characters TOP-TO-BOTTOM EMBEDDING and
BOTTOM-TO-TOP EMBEDDING, with similar scope until the next PDF
character. The difficult part would be implementing this, and before
that defining the exact semantics (but Unicode could define the
semantics as beyond its scope). (Another problem would be deciding which
variant of mirrored characters e.g. brackets to use given that the
context is neither RTL nor LTR - this is a problem with Egyptian
hieroglyphs, many of which are mirrored in horizontal text.)
--
Peter Kirk
[EMAIL PROTECTED] (personal)
[EMAIL PROTECTED] (work)
http://www.qaya.org/
