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 | | From: | Roger Leigh | | Subject: | ECMA-48 and Unicode | | Date: | Tue, 11 Jan 2005 23:11:23 +0000 |
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Hello,
I've been reading up on terminal emulation standards recently, and I
have found a few questions about them. I hope someone in this group
might possibly know the answers, or point me to the relevant
documentation.
I've read the DEC VT-100 manual, ECMA-35, ECMA-43 and ECMA-48. I'd
also like to read some of the referenced ISO standards in addition,
but they are rather expensive.
Some terminals (e.g. XTerm, GNOME-terminal) support double-width
Unicode characters. The cursor positioning functions (e.g. CHA, CUP)
move the cursor to a specific position. Is this the character cell
number, or the character number on the line? If this is character
number, what happens if you are writing text into a previously-drawn
box--will it mess up the line-drawing character alignment?
Is there any reference about how 2/3/4-cell-width chars behave?
ECMA-48 specifies a data component and a presentation component. Are
there any examples of the relationship between the two? I can see
that the data component is required to process e.g. reversed strings,
but if the reversing can extend over multiple lines, this would also
require the reversing of a set of (possibly partial) lines. I can see
this would be possible, but I can't see how this would be possible if
one can position the cursor at arbitrary positions in either component
if this were the case. There are some examples in the TR-053
appendix, but I didn't find them particularly enlightening.
Do any free software terminal emulators actually implement this
separation?
Many thanks,
Roger
- --
Roger Leigh
Printing on GNU/Linux? http://gimp-print.sourceforge.net/
Debian GNU/Linux http://www.debian.org/
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