.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_kernel.3x,v 1.53 2024/01/05 21:46:58 tom Exp $
-.TH curs_kernel 3X 2024-01-05 "ncurses 6.4" "Library calls"
+.\" $Id: curs_kernel.3x,v 1.63 2024/05/25 21:13:56 tom Exp $
+.TH curs_kernel 3X 2024-05-25 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
.ie \n(.g \{\
.ds `` \(lq
.ds '' \(rq
\fB\%savetty\fP,
\fB\%getsyx\fP,
\fB\%setsyx\fP,
-\fB\%ripoffline\fP,
\fB\%curs_set\fP,
-\fB\%napms\fP \-
+\fB\%mvcur\fP,
+\fB\%napms\fP,
+\fB\%ripoffline\fP \-
low-level \fIcurses\fR routines
.SH SYNOPSIS
.nf
\fBvoid getsyx(int \fIy\fP, int \fIx\fP);
\fBvoid setsyx(int \fIy\fP, int \fIx\fP);
.PP
-\fBint ripoffline(int \fIline\fP, int (*\fIinit\fP)(WINDOW *, int));
\fBint curs_set(int \fIvisibility\fP);
+\fBint mvcur(int \fIoldrow\fP, int \fIoldcol\fP, int \fInewrow\fP, int \fInewcol\fP);
\fBint napms(int \fIms\fP);
+\fBint ripoffline(int \fIline\fP, int (*\fIinit\fP)(WINDOW *, int));
.fi
.SH DESCRIPTION
The following routines give low-level access
.PP
Few applications will use this feature,
most use \fBwmove\fP instead.
+.SS curs_set
+The \fBcurs_set\fP routine sets the cursor state to invisible,
+normal, or very visible for \fBvisibility\fP equal to \fB0\fP,
+\fB1\fP, or \fB2\fP respectively.
+If the terminal supports the \fIvisibility\fP requested,
+the previous \fIcursor\fP state is returned;
+otherwise, \fBERR\fP is returned.
+.SS mvcur
+.B \%mvcur
+provides low-level cursor motion.
+It takes effect immediately,
+rather than at the next refresh.
+Unlike the other low-level output functions,
+which either write to the standard output stream
+or are passed a function pointer to perform output,
+.B \%mvcur
+uses a file descriptor derived from the output stream parameter of
+\fB\%newterm\fP(3X).
+.PP
+One application of
+.B \%mvcur
+accompanies the temporary use of another program to write to the
+terminal screen.
+For example,
+first call \fB\%refresh\fP(3X) to ensure that the screen and the
+library's model of it is up to date;
+then call
+.BR \%reset_shell_mode ";"
+write to the screen with the external application;
+call
+.BR \%reset_prog_mode ";"
+and finally call
+.B \%mvcur
+to set the cursor's location to where
+.I \%curses
+thinks it is,
+since the library has no knowledge of how the external application
+moved it.
+.\" https://lists.gnu.org/archive/html/bug-ncurses/2016-10/msg00002.html
+.SS napms
+.B \%napms
+sleeps for
+.I ms
+milliseconds.
+If
+.I ms
+exceeds 30,000
+(thirty seconds),
+it is capped at that value.
.SS ripoffline
-The \fBripoffline\fP routine provides access to the same facility that
-\fBslk_init\fP [see \fBcurs_slk\fP(3X)] uses to reduce the size of the
-screen.
-\fBripoffline\fP must be called before \fBinitscr\fP or
+.B \%ripoffline
+provides access to the same facility that \fB\%slk_init\fP(3X) uses to
+reduce the size of the screen.
+\fB\%ripoffline\fP must be called before \fBinitscr\fP or
\fBnewterm\fP is called, to prepare these initial actions:
.bP
If \fIline\fP is positive, a line is removed from the top of \fBstdscr\fP.
.PP
\fBripoffline\fP can be called up to five times before calling \fBinitscr\fP or
\fBnewterm\fP.
-.SS curs_set
-The \fBcurs_set\fP routine sets the cursor state to invisible,
-normal, or very visible for \fBvisibility\fP equal to \fB0\fP,
-\fB1\fP, or \fB2\fP respectively.
-If the terminal supports the \fIvisibility\fP requested,
-the previous \fIcursor\fP state is returned;
-otherwise, \fBERR\fP is returned.
-.SS napms
-The \fBnapms\fP routine is used to sleep for \fIms\fP milliseconds.
-If the value of \fIms\fP exceeds 30,000
-(thirty seconds),
-it is capped at that value.
.SH RETURN VALUE
Except for \fBcurs_set\fP, these routines always return \fBOK\fP.
.PP
In this implementation
.TP 5
\fBdef_prog_mode\fP, \fBdef_shell_mode\fP, \fBreset_prog_mode\fP, \fBreset_shell_mode\fP
-return an error
+return
+.B ERR
if the terminal was not initialized, or
if the I/O call to obtain the terminal settings fails.
.TP 5
\fBripoffline\fP
-returns an error if the maximum number of ripped-off lines
+returns
+.B ERR
+if the maximum number of ripped-off lines
exceeds the maximum (5).
.SH NOTES
Note that \fBgetsyx\fP is a macro, so \fB&\fP is not necessary before
invisible or very visible.
There is no way for \fI\%ncurses\fP to determine the initial cursor
state to restore that.
+.SH EXTENSIONS
+In
+.IR \%ncurses ","
+.B \%mvcur
+accepts
+.B \-1
+for either or both old coordinates.
+This value tells
+.I \%ncurses
+that the old location is unknown,
+and that it must use only absolute motion,
+as with the
+.B \%cursor_address
+.RB ( cup )
+capability,
+rather than the least costly combination of absolute and relative
+motion.
.SH PORTABILITY
The \fIvirtual screen\fP functions \fBsetsyx\fP and \fBgetsyx\fP
-are not described in the XSI Curses standard, Issue 4.
-All other functions are as described in XSI Curses.
+are not described in X/Open Curses, Issue 4.
+All other functions are as described in X/Open Curses.
.PP
The SVr4 documentation describes \fBsetsyx\fP and \fBgetsyx\fP
as having return type int.
This is misleading, as they are macros with no documented semantics
for the return value.
.PP
+X/Open Curses notes:
+.RS
+.PP
+\*(``After use of
+.IR \%mvcur "(),"
+the model Curses maintains of the state of the terminal might not
+match the actual state of the terminal.
+An application should touch and refresh the window before
+resuming conventional use of Curses.\*(''
+.RE
+.PP
+Both
+.I \%ncurses
+and SVr4
+.I curses
+implement
+.B \%mvcur
+using the
+.I SCREEN
+data allocated in either \fB\%initscr\fP(3X) or \fB\%newterm\fP(3X).
+X/Open Curses states that the old location must be given for
+.B \%mvcur
+to accommodate terminals that lack absolute cursor positioning.
+.\" X/Open Curses Issue 7, p. 161
+.PP
If interrupted, \fI\%ncurses\fP restarts \fBnapms\fP.
That, and the limitation to 30 seconds,
are different from other implementations.
projects / ncurses.git / blobdiff