rxvt and line-drawing characters

[Charles Wilson]

Charles Wilson wrote:
> Strangely, if I set TERM=rxvt-cygwin-native , use luconP as my font , it 
> does NOT matter whether my CYGWIN variable has codepage:oem, 
> codepage:ansi, or neither.  The following behaviors are the same:
> 
> ascii.exe prints the line draw characters
> pstree -G prints garbage
> 
> It *could be* due to the fact that pstree uses ncurses, and ascii does 
> not.   Checking...
> 
> Hmmm.  /usr/lib/ncurses/test/ncurses.exe (part of the ncurses-demo 
> package) turns the screen black-on-black when I try to check the 
> line-draw characters.  So I can't even tell if ACS chars with ncurses is 
> broken -- first I gotta figure out why the colors are getting scrogged 
> by the test program!  Somebody, like the ncurses maintainer, should fix 
> that.
> 
> Oh.  That'd be me, then.  Ooops.  I'll try to look into it soon, but PTC.

Okay, so I've looked into this.

(1) the ncurses "problem" is not a problem.  The ncurses.exe test 
program leaves the decision as to whether to use colorfgbg() defaults up 
to the user (-a fg,bg to explicitly specify defaults, -d to inherit 
defaults from rxvt, or '' to use the DEFAULT defaults.  Which is, 
apparently, black on black -- at least when run in an rxvt shell.)

So, running ncurses.exe with -d, (or, for that matter, the hideous -a 
1,4 == red-on-blue, unless you've redefined rxvt's colors) works fine. 
With

   rxvt -fn 'Lucida ConsoleP-16' -tn rxvt-cygwin-native -e /bin/bash

I get nice line draw characters from the ncurses.exe test program.  With

   rxvt -fn 'Lucida Console-16' -tn rxvt-cygwin-native -e /bin/bash

I get "european" characters where the line drawing ones used to be. Just 
as expected.  Also, codepage:oem|ansi has no effect -- it only applies 
when using the windows console, not when using rxvt.

(2) So why does pstree misbehave? Because it's hardcoded to use VT-100 
control characters for line drawing.  But that's EXACTLY where rxvt 
differs from VT-100 (and where rxvt-cygwin differs from rxvt, and where 
rxvt-cygwin-native differs from them all).

pstree SHOULD be using tgetent() calls to dynamically obtain the 
appropriate line-drawing character codes and escape sequences from 
ncurses/terminfo.  But it doesn't.

(There's also a similar bug in that it doesn't always calculate 
accurately the width of strings in which these line-draw chars are 
embedded...but that's a whole 'nother thing.)

Basically, pstree -G should be rewritten; it's just not going to work on 
cygwin's rxvt (native or X) very well.

"It's surely evil code"
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=265552


Basically, you're stuck with 'pstree -A'.

--
Chuck


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