Klemens Nanni wrote in
<20200603124948.irvdnxrxa5g75pmi@eru>:
|On Wed, Jun 03, 2020 at 12:45:35PM +0100, Stuart Henderson wrote:
|> It should check terminal capabilities for this, see termcap(5).
|> If 'am' (auto-margin) is set then it shouldn't write to the final column.
|> If 'xn' is set then it's OK in some circumstances (it's probably \
|> easier to
|> skip writing to the final column if this is set too).
|Thanks mark and Stuart, I did not know about auto-margin (or autoWrap as
|xterm(1) seems to call it).
|
|What I understand is that writing to the screen's last terminal should
|be avoided in terminal without the "am" capability, presumably because
|it would cause a line wrap - is that correct?
|
|Preliminary testing however indicates to me that at least xterm(1)
|behaves the same in top's interactive screen with my patch, regardless
|of the auto-margin capablility.
|
|According to termcap(5) I did the following to disable "am", with
|tput(1) I verify that it gets indeed disabled:
|
| $ echo $TERM ; tput am ; echo $?
| xterm
| 0
| $ TERM=vt100-nam ; tput am ; echo $?
| 1
|
|But in both cases, starting ./obj/top in the very same terminal/shell
|behaves the same, that is to say the last column is written properly and
|I see no line wrap or any change of behaviour.
I do not think that you en- or disable "am", it indicates whether
the terminal has the capability or not. I have
n_TERMCAP_QUERY_am, /* am/am, BOOL | auto_right_margin */
n_TERMCAP_QUERY_sam, /* sam/YE, BOOL | semi_auto_right_margin */
n_TERMCAP_QUERY_xenl, /* xenl/xn, BOOL | eat_newline_glitch */
... ^^terminfo/termcap^^ names | terminfo variable
eat_newline_glitch ensures that \n written after margin does not
cause a line wrap.
/* TODO We do not handle !n_TERMCAP_QUERY_sam in this software! */
if(!n_termcap_query(n_TERMCAP_QUERY_am, &tv) ||
n_termcap_query(n_TERMCAP_QUERY_xenl, &tv))
n_psonce |= n_PSO_TERMCAP_FULLWIDTH;
...
/* Then search for right boundary. Dependent upon n_PSO_FULLWIDTH (termcap
* am/xn) We leave the rightmost column empty because some terminals
* [cw]ould wrap the line if we write into that, or not.
* TODO We do not deal with !n_TERMCAP_QUERY_sam */
--End of <20200603124948.irvdnxrxa5g75pmi@eru>
--steffen
|
|Der Kragenbaer, The moon bear,
|der holt sich munter he cheerfully and one by one
|einen nach dem anderen runter wa.ks himself off
|(By Robert Gernhardt)
