curs_slk.3x - Man Page

curses soft label key routines

Synopsis

#include <curses.h>

int slk_init(int fmt);

int slk_set(int labnum, const char *label, int align);
int slk_wset(int labnum, const wchar_t *label, int align);

char *slk_label(int labnum);

int slk_refresh(void);
int slk_noutrefresh(void);
int slk_clear(void);
int slk_restore(void);
int slk_touch(void);

int slk_attron(const chtype attrs);
int slk_attroff(const chtype attrs);
int slk_attrset(const chtype attrs);
int slk_attr_on(attr_t attrs, void *opts);
int slk_attr_off(const attr_t attrs, void *opts);
int slk_attr_set(const attr_t attrs, short pair, void*opts);
/* extension */
attr_t slk_attr(void);

int slk_color(short pair);
/* extension */
int extended_slk_color(int pair);

Description

These functions manipulate the soft function key labels that some hardware terminals support. For those terminals that do not have soft labels, curses takes over the bottom line of stdscr, reducing its vertical size and the value of LINES by one. By default, curses uses eight labels of up to eight characters each.

ncurses furthermore supports a mode comprising twelve labels of up to five characters each, following a convention associated with the IBM PC/AT keyboard. ncurses simulates this mode by taking over up to two lines at the bottom of the screen; it does not try to use any hardware support for this mode.

Initialization

slk_init must be called before initscr or newterm. If initscr eventually uses a line from stdscr to emulate the soft labels, then fmt determines how the labels are arranged on the screen.

0

indicates a 3-2-3 arrangement of the labels.

1

indicates a 4-4 arrangement

2

indicates the PC-like 4-4-4 mode.

3

is again the PC-like 4-4-4 mode, but in addition an index line is generated, helping the user to associate each label with its numbered function key. LINES and the vertical size of stdscr are further reduced.

Labels

Populate the labels with normal strings (slk_set) or wide-character strings (slk_wset). Each function takes three parameters.

labnum

is the label number, from 1 to 8 (12 if fmt in slk_init is 2 or 3);

label

is be the string to put on the label, up to eight (five if fmt in slk_init is 2 or 3) characters in length. A empty string or a null pointer sets up a blank label.

align

is 0, 1, or 2, aligning label to the left, center, or right, respectively, within the 8 (5) character cells housing it.

slk_label obtains the string assigned to label number labnum, with any leading and trailing blanks stripped.

Screen Updates

slk_refresh and slk_noutrefresh affect the soft key label lines as wrefresh and wnoutrefresh do the curses window.

The slk_clear routine clears the soft labels from the screen.

The slk_restore routine restores the soft labels to the screen after a slk_clear has been performed.

The slk_touch routine forces all the soft labels to be output the next time a slk_noutrefresh is performed.

Video Attributes

The slk_attron, slk_attrset, slk_attroff, and slk_attr routines correspond to attron, attrset, attroff, and attr_get, respectively. They have an effect only if soft labels are simulated on the bottom line of the screen. The default highlight for soft key labels is A_STANDOUT (as in System V curses, which does not document this fact).

Colors

The slk_color routine corresponds to color_set. It has an effect only if soft labels are simulated on the bottom line of the screen.

Because slk_color accepts only short (signed 16-bit integer) values, this implementation provides extended_slk_color, which accepts an int value of at least 32 bits.

Return Value

Routines that return an integer return ERR upon failure and OK (SVr4 specifies only “an integer value other than ERR”) upon successful completion.

X/Open Curses defines no error conditions.

In this implementation

slk_attr

returns the attribute used for the soft keys.

slk_attroff,  slk_attron,  slk_clear,  slk_noutrefresh,  slk_refresh,  slk_touch

return an error if the terminal or the softkeys were not initialized.

slk_attrset

returns an error if the terminal or the softkeys were not initialized.

slk_attr_set

returns an error if the terminal or the softkeys were not initialized, or the color pair is outside the range 0..COLOR_PAIRS-1.

slk_color

returns an error if the terminal or the softkeys were not initialized, or the color pair is outside the range 0..COLOR_PAIRS-1.

slk_init

returns an error if the format parameter is outside the range 0..3.

slk_label

returns NULL on error.

slk_set

returns an error if the terminal or the softkeys were not initialized, or the labnum parameter is outside the range of label counts, or if the format parameter is outside the range 0..2, or if memory for the labels cannot be allocated.

Notes

Most applications would use slk_noutrefresh because a wrefresh is likely to follow soon.

Extensions

X/Open Curses documents the opts argument as reserved for future use, saying that it must be null. This implementation uses that parameter in ABI 6 for the functions which have a color pair parameter to support extended color pairs.

For functions which modify the color, e.g., slk_attr_set, if opts is set it is treated as a pointer to int, and used to set the color pair instead of the short pair parameter.

Portability

X/Open Curses, Issue 4, describes these functions, with some differences from SVr4 curses:

Although slk_start is declared in the curses header file, it was not documented by SVr4 other than its presence in a list of libtermlib.so.1 symbols. Reading the source code (i.e., Illumos):

The function slk_attr was added by ncurses in 1996.

X/Open Curses does not specify a limit for the number of colors and color pairs which a terminal can support. However, in its use of short for the parameters, it carries over SVr4's implementation detail for the compiled terminfo database, which uses signed 16-bit numbers. This implementation provides extended versions of those functions which use int parameters, allowing applications to use larger color- and pair-numbers.

History

SVr3 introduced these functions:
 slk_clear
 slk_init
 slk_label
 slk_noutrefresh
 slk_refresh
 slk_restore
 slk_set
 slk_touch

SVr4 added these functions:
 slk_attroff
 slk_attron
 slk_attrset
 slk_start

X/Open Curses added these:
 slk_attr_off
 slk_attr_on
 slk_attr_set
 slk_color
 slk_wset

See Also

curses(3X), curs_attr(3X), curs_initscr(3X), curs_refresh(3X), curs_variables(3X)

Referenced By

The man pages extended_slk_color.3x(3), slk_attr.3x(3), slk_attr_off.3x(3), slk_attroff.3x(3), slk_attr_on.3x(3), slk_attron.3x(3), slk_attr_set.3x(3), slk_attrset.3x(3), slk_clear.3x(3), slk_color.3x(3), slk_init.3x(3), slk_label.3x(3), slk_noutrefresh.3x(3), slk_refresh.3x(3), slk_restore.3x(3), slk_set.3x(3), slk_touch.3x(3) and slk_wset.3x(3) are aliases of curs_slk.3x(3).

2023-12-16 ncurses 6.4 Library calls