Bidi paragraph direction in terminal emulators (was: Proposal for BiDi in terminal emulators)

Eli Zaretskii via Unicode unicode at
Fri Feb 8 03:34:29 CST 2019

> Date: Fri, 8 Feb 2019 06:40:44 +0000
> From: Richard Wordingham via Unicode <unicode at>
> > I, for one, am not to the slightest bit interested in abandoning the
> > character grid and allowing for proportional fonts. This would just
> > break a gazillion of things.
> The message I take from that and this thread in general is that Emacs
> and 'M-x term' are the route to take if one only has proportional fonts.

Not sure why.  There are terminal emulators out there which support
proportional fonts.  Emacs is perhaps the only one whose terminal
emulator currently supports bidi more or less in full, but is that
related to proportional fonts?

> What's the sledgehammer for Windows?

Not sure what you meant.  "M-x term" doesn't work on Windows.

> Where do I find the specification for fixed-width fonts (is
> wcswidth() the core?) and how do I select the set of fonts to use?  Do I
> need to use fontconfig where available?

That depends on the underlying C library and other facilities;
basically on your OS.  AFAIK wcwidth will give the results consistent
with the UCD only if you use glibc.  In Emacs, you have the functions
char-width and string-width that take their data from
EastAsianWidth.txt.  Not sure about other facilities, and I don't
really understand what environment are you asking about -- are you
talking about C/C++ programs?

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