.\"	$NetBSD: curses_slk.3,v 1.2 2018/09/29 22:04:57 kamil Exp $
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.Dd September 29, 2018
.Dt CURSES_SLK 3
.Os
.Sh NAME
.Nm slk_attroff ,
.Nm slk_attr_off ,
.Nm slk_attron ,
.Nm slk_attr_on ,
.Nm slk_attrset ,
.Nm slk_attr_set ,
.Nm slk_clear ,
.Nm slk_color ,
.Nm slk_init ,
.Nm slk_label ,
.Nm slk_noutrefresh ,
.Nm slk_refresh ,
.Nm slk_restore ,
.Nm slk_set ,
.Nm slk_touch ,
.Nm slk_wset
.Nd Curses soft label key routines
.Sh LIBRARY
.Lb libcurses
.Sh SYNOPSIS
.In curses.h
.Ft int
.Fn slk_attroff "const chtype attr"
.Ft int
.Fn slk_attr_off "const attr_t attr" "void *opt"
.Ft int
.Fn slk_attron "const chtype attr"
.Ft int
.Fn slk_attr_on "const attr_t attr" "void *opt"
.Ft int
.Fn slk_attrset "const chtype attr"
.Ft int
.Fn slk_attr_set "const attr_t attr" "short pair" "void *opt"
.Ft void
.Fn slk_clear "void"
.Ft int
.Fn slk_color "short pair"
.Ft int
.Fn slk_init "int fmt"
.Ft char *
.Fn slk_label "int labnum"
.Ft int
.Fn slk_noutrefresh "void"
.Ft int
.Fn slk_refresh "void"
.Ft int
.Fn slk_restore "void"
.Ft int
.Fn slk_set "int labnum" "const char *label" "int justify"
.Ft int
.Fn slk_touch "void"
.Ft int
.Fn slk_wset "int labnum" "const wchar_t *label" "int justify"
.Sh DESCRIPTION
This Curses interface manipulates the set of soft function-key labels that
exist on some terminals.
For those terminals that do not have soft labels, Curses takes over the bottom
line of
.Dv stdstr ,
reducing the size of
.Dv stdscr
and the value of the
.Dv LINES
external variable.
There can be up to eight labels of up to eight display columns each.
.Pp
To use soft labels,
.Fn slk_init
must be called before
.Xr initscr 3 ,
.Xr newterm 3 ,
or
.Xr ripoffline 3
is called.
If
.Xr newterm 3
eventually uses a line from
.Dv stdscr
to emulate the soft labels, then
.Fa fmt
determines how the labels are arranged on the screen from the following list:
.Bl -tag -width ERR -compact
.It 0
indicates a 3-2-3 arrangement.
.It 1
indicates a 4-4 arrangement.
.El
.Pp
The
.Fn slk_set
and
.Fn slk_wset
functions specify the text of soft label number
.Fa labnum ,
within the range from 1 to 8 inclusive.
The
.Fa label
argument is the string to be put on the label.
The
.Fa justify
argument can have the following values to indicate how to justify
.Fa label
within the space reserved for it:
.Bl -tag -width ERR -compact
.It 0
Left align.
.It 1
Center align.
.It 2
Right align.
.El
.Pp
The
.Fn slk_refresh
and
.Fn slk_noutrefresh
functions correspond to the
.Xr wrefresh 3
and
.Xr wnoutrefresh 3
functions.
.Pp
The
.Fn slk_label
function returns a pointer to the text displayed in the label.
.Pp
The
.Fn slk_clear
function immediately clears the soft labels from the screen.
.Pp
The
.Fn slk_restore
function immediately restores the soft labels to the screen after a call to
.Fn slk_clear .
.Pp
The
.Fn slk_touch
function forces all soft labels to be output the next time
.Fn slk_noutrefresh
or
.Fn slk_refresh
is called.
.Pp
The
.Fn slk_attron ,
.Fn slk_attrset
and
.Fn slk_attroff
functions correspond to
.Xr attron 3 ,
.Xr attrset 3
and
.Xr attroff 3 .
The have an effect only if soft labels are simulated on the bottom line of the
screen.
.Pp
The
.Fn slk_attr_on ,
.Fn slk_attr_set ,
.Fn slk_color
and
.Fn slk_attr_off
functions correspond to
.Xr attr_on 3 ,
.Xr attr_set 3 ,
.Xr color_set 3
and
.Xr attr_off 3
and thus support the attribute constants with the WA_ prefix and color.
The have an effect only if soft labels are simulated on the bottom line of the
screen.
.Pp
The
.Fa opt
argument is reserved for future use.
Currently the application must provide a NULL pointer as
.Fa opt .
.Sh RETURN VALUES
Functions returning pointers will return
.Dv NULL
if an error is detected.
The functions that return an int will return one of the following
values:
.Pp
.Bl -tag -width ERR -compact
.It Er OK
The function completed successfully.
.It Er ERR
An error occurred in the function.
.El
.Sh SEE ALSO
.Xr terminfo 5
.Sh NOTES
This has not been tested on a terminal with real soft label keys.
.Dv label_height ,
.Dv label_width ,
.Dv label_format
and
.Dv lab_f*
are currently not used.
.Sh STANDARDS
The
.Nx
Curses library complies with the X/Open Curses specification, part of the
Single Unix Specification.
.Sh HISTORY
The Curses package appeared in
.Bx 4.0 .
The soft label key functions were added in
.Nx 8.0 .