[EMAIL PROTECTED] wrote on 2001-05-16 12:52 UTC:
> As we all know, ISO2022 compliant terminals have CL,CR,GL,GR which are
> mapped to C0,C1,G0,G1,G2,G3. When we use an ISO2022 escape to switch
> to UTF8 mode for instance we given up the ability to manipulate the
> mappings between GL/GR and G0-G3. I would argue that if we provide
> ISO2022 escapes to use IBM/MS code pages that we would in turn be
> giving up the ability to perform those manipulations. This is turn
> would mean that IBM/MS Code Pages could not be used in conjunction
> with the Graphics or Box drawing character sets of VT terminals.
Agreed. Just like you can't use the GL Graphics or Box drawing character
sets of VT terminals any more in UTF-8 mode, unless you use the U+25xx
Unicode characters for that purpose.
> Are you are proposing that an update to ISO2022 be issued that defines
> a new mode that combines CR+GR into a single entity for the purposes
> of mapping to
>
> C1+G0 C1+G1 C1+G2 C1+G3
>
> but keep the ability to manipulate the mappings of GL/GR? If so, I
> do not see how this would work.
I thought that would be one feasible way. Note that MS-DOS/CGA has even
graphical characters in the CL range. We certainly can't support these
in the Cl range, but they could be mapped into the CR range for
instance. I'm note sure myself however, whether that is really worth the
effort of revision ISO 2022.
> The only possible scenario that I can see is the use of ISO2022
> escapes which would disable the use of ISO2022 until a suitable return
> sequence is issued. This may be suitable for some applications.
Agreed.
> However, I believe it will break most terminfo/termcap entries that
> assume ISO2022 is used for box drawing.
Just like UTF-8 does. There are already applications around that
deactivate the DEC block graphics in UTF-8 locales and use the U+25xx
codes instead. W3m-m17n <http://www2u.biglobe.ne.jp/~hsaka/w3m/> is a
very nice example that makes good use of UTF-8 block graphics when in
UTF-8 mode. Absolutely don't use any terminfo/termcap entries for block
graphics when you are in UTF-8 mode!
Markus
--
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
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Linux-UTF8: i18n of Linux on all levels
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