Re: [bug-ncurses] How to use `rep' in xterm since ncurses-6.0-20170729

[Thomas Dickey]

On Wed, Sep 20, 2017 at 02:33:03PM +0200, Dr. Werner Fink wrote:
> On Wed, Sep 20, 2017 at 05:04:01AM -0400, Thomas Dickey wrote:
> > On Wed, Sep 20, 2017 at 10:52:53AM +0200, Dr. Werner Fink wrote:
> > > 
> > > I meant that I see exactly the same within XTerm with 112 113 114 115
> > > but not with p q r s
> > 
> > That's because tput doesn't know how to convert "p q r s" into numbers.
> > I could make it report an error and quit...
> 
> Stupid question: does hline(), hline(), mvhline(), and mvvline() use
> repeat_char if found in the current terminfo entry?  And how do those
> functions the given character, e.g. ' ' or '-' ...

The repeat function is done at a low level, as ncurses translates screen
updates to escape sequences.

This chunk in tty_update.c is what decides if the repeat is used:

                    } else if (repeat_char != 0 &&
        #if USE_WIDEC_SUPPORT
                               (!SP_PARM->_screen_unicode &&
                                ((AttrOf(ntext0) & A_ALTCHARSET) == 0 ||
                                 (CharOf(ntext0) < ACS_LEN))) &&
        #endif
                               runcount > SP_PARM->_rep_cost) {
 
Essentially it says that if there's enough repetition on a horizontal
line (no verticals...), and the previous cell on the screen is a
narrow character, then it's okay to repeat that.

> I've reports about ncdu (NCurses Disk Usage) as well as about other
> ncurses based applications about wrong/missing line drawings

If it's for ncurses 20170829 or later and xterm (any recent version),
I can address that.

For those other terminal emulators - the developers have been advised
repeatedly that setting TERM=xterm (or anything derived from xterm) is a bad
idea.  We'll have similar discussions in the future.

-- 
Thomas E. Dickey <address@hidden>
http://invisible-island.net
ftp://ftp.invisible-island.net

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