curs_threads(3X) Library calls curs_threads(3X)

NCURSES_WINDOW_CB, NCURSES_SCREEN_CB, get_escdelay, set_escdelay, set_tabsize, use_screen, use_window - curses support for multi-threaded applications

#include <curses.h>
/* data types */
typedef int (*NCURSES_WINDOW_CB)(WINDOW *, void *);
typedef int (*NCURSES_SCREEN_CB)(SCREEN *, void *);
int get_escdelay(void);
int set_escdelay(int ms);
int set_tabsize(int cols);
int use_screen(SCREEN *scr, NCURSES_SCREEN_CB func, void *data);
int use_window(WINDOW *win, NCURSES_WINDOW_CB func, void *data);

The ncurses library can be configured to support multi-threaded applications in a rudimentary way. Such configuration produces a different set of libraries, named libncursest, for example, since doing so alters ncurses's application binary interface (ABI).

Instead of modifying the programming interface (API) to make ncurses functions expect an additional argument specifying a thread, the library adds functions, usable in any configuration, that hide the mutexes (mutual exclusion locks) needed to prevent concurrent access to variables shared by multiple threads of execution.

ncurses threading support requires the use of functions to access members of the WINDOW structure (see curs_opaque(3X)). It further makes functions of the common global variables COLORS, COLOR_PAIRS, COLS, ESCDELAY, LINES, TABSIZE, curscr, newscr, and ttytype, maintaining them as as read-only values in the SCREEN structure.

Even this is not enough to make an application using curses thread-safe. We would expect a multi-threaded application to have threads updating separate windows (on the same device), and separate screens (on different devices). Further, applications expect a few of the global variables to be writable. The functions described here address these special situations.

The ESCDELAY and TABSIZE global variables are modified by some applications. To modify them in any configuration, use the set_escdelay or set_tabsize functions. Other global variables are not modifiable. get_escdelay retrieves ESCDELAY's value.

The use_window and use_screen functions provide coarse-grained mutexes for their respective WINDOW and SCREEN parameters; they call a user-supplied function, pass it a data parameter, and return the value from the user-supplied function to the application.

All ncurses library functions assume that the locale is not altered during operation. In addition, they use data that is maintained within a hierarchy of scopes.

  • global data used in the low-level terminfo or termcap interfaces
  • terminal data associated with a call to set_curterm(3X)
Terminal data are initialized when screens are created.
Windows are associated with screens. Pads are not necessarily associated with any particular screen.
Most curses applications operate on one or more windows within a single screen.
reentrant data associated with “pure” functions that alter no shared variables

The following table lists the scope of each symbol in the ncurses library when configured to support multi-threaded applications.

Symbol Scope
BC global
COLORS screen (read-only)
COLOR_PAIR reentrant
COLOR_PAIRS screen (read-only)
COLS screen (read-only)
ESCDELAY screen (read-only; see set_escdelay)
LINES screen (read-only)
PAIR_NUMBER reentrant
PC global
SP global
TABSIZE screen (read-only; see set_tabsize)
UP global
acs_map screen (read-only)
add_wch window (stdscr)
add_wchnstr window (stdscr)
add_wchstr window (stdscr)
addch window (stdscr)
addchnstr window (stdscr)
addchstr window (stdscr)
addnstr window (stdscr)
addnwstr window (stdscr)
addstr window (stdscr)
addwstr window (stdscr)
assume_default_colors screen
attr_get window (stdscr)
attr_off window (stdscr)
attr_on window (stdscr)
attr_set window (stdscr)
attroff window (stdscr)
attron window (stdscr)
attrset window (stdscr)
baudrate screen
beep screen
bkgd window (stdscr)
bkgdset window (stdscr)
bkgrnd window (stdscr)
bkgrndset window (stdscr)
boolcodes global (read-only)
boolfnames global (read-only)
boolnames global (read-only)
border window (stdscr)
border_set window (stdscr)
box window (stdscr)
box_set window (stdscr)
can_change_color terminal
cbreak screen
chgat window (stdscr)
clear window (stdscr)
clearok window
clrtobot window (stdscr)
clrtoeol window (stdscr)
color_content screen
color_set window (stdscr)
copywin window (locks source, target)
cur_term terminal
curs_set screen
curscr screen (read-only)
curses_version global (read-only)
def_prog_mode terminal
def_shell_mode terminal
define_key screen
del_curterm screen
delay_output screen
delch window (stdscr)
deleteln window (stdscr)
delscreen global (locks screen list, screen)
delwin global (locks window list)
derwin screen
doupdate screen
dupwin screen (locks window)
echo screen
echo_wchar window (stdscr)
echochar window (stdscr)
endwin screen
erase window (stdscr)
erasechar window (stdscr)
erasewchar window (stdscr)
filter global
flash terminal
flushinp screen
get_wch screen (input operation)
get_wstr screen (input operation)
getattrs window
getbegx window
getbegy window
getbkgd window
getbkgrnd window
getcchar reentrant
getch screen (input operation)
getcurx window
getcury window
getmaxx window
getmaxy window
getmouse screen (input operation)
getn_wstr screen (input operation)
getnstr screen (input operation)
getparx window
getpary window
getstr screen (input operation)
getwin screen (input operation)
halfdelay screen
has_colors terminal
has_ic terminal
has_il terminal
has_key screen
hline window (stdscr)
hline_set window (stdscr)
idcok window
idlok window
immedok window
in_wch window (stdscr)
in_wchnstr window (stdscr)
in_wchstr window (stdscr)
inch window (stdscr)
inchnstr window (stdscr)
inchstr window (stdscr)
init_color screen
init_pair screen
initscr global (locks screen list)
innstr window (stdscr)
innwstr window (stdscr)
ins_nwstr window (stdscr)
ins_wch window (stdscr)
ins_wstr window (stdscr)
insch window (stdscr)
insdelln window (stdscr)
insertln window (stdscr)
insnstr window (stdscr)
insstr window (stdscr)
instr window (stdscr)
intrflush terminal
inwstr window (stdscr)
is_cleared window
is_idcok window
is_idlok window
is_immedok window
is_keypad window
is_leaveok window
is_linetouched window
is_nodelay window
is_notimeout window
is_scrollok window
is_syncok window
is_term_resized terminal
is_wintouched window
isendwin screen
key_defined screen
key_name global (static data)
keybound screen
keyname global (static data)
keyok screen
keypad window
killchar terminal
killwchar terminal
leaveok window
longname screen
mcprint terminal
meta screen
mouse_trafo window (stdscr)
mouseinterval screen
mousemask screen
move window (stdscr)
mvadd_wch window (stdscr)
mvadd_wchnstr window (stdscr)
mvadd_wchstr window (stdscr)
mvaddch window (stdscr)
mvaddchnstr window (stdscr)
mvaddchstr window (stdscr)
mvaddnstr window (stdscr)
mvaddnwstr window (stdscr)
mvaddstr window (stdscr)
mvaddwstr window (stdscr)
mvchgat window (stdscr)
mvcur screen
mvdelch window (stdscr)
mvderwin window (stdscr)
mvget_wch screen (input operation)
mvget_wstr screen (input operation)
mvgetch screen (input operation)
mvgetn_wstr screen (input operation)
mvgetnstr screen (input operation)
mvgetstr screen (input operation)
mvhline window (stdscr)
mvhline_set window (stdscr)
mvin_wch window (stdscr)
mvin_wchnstr window (stdscr)
mvin_wchstr window (stdscr)
mvinch window (stdscr)
mvinchnstr window (stdscr)
mvinchstr window (stdscr)
mvinnstr window (stdscr)
mvinnwstr window (stdscr)
mvins_nwstr window (stdscr)
mvins_wch window (stdscr)
mvins_wstr window (stdscr)
mvinsch window (stdscr)
mvinsnstr window (stdscr)
mvinsstr window (stdscr)
mvinstr window (stdscr)
mvinwstr window (stdscr)
mvprintw window (stdscr)
mvscanw screen
mvvline window (stdscr)
mvvline_set window (stdscr)
mvwadd_wch window
mvwadd_wchnstr window
mvwadd_wchstr window
mvwaddch window
mvwaddchnstr window
mvwaddchstr window
mvwaddnstr window
mvwaddnwstr window
mvwaddstr window
mvwaddwstr window
mvwchgat window
mvwdelch window
mvwget_wch screen (input operation)
mvwget_wstr screen (input operation)
mvwgetch screen (input operation)
mvwgetn_wstr screen (input operation)
mvwgetnstr screen (input operation)
mvwgetstr screen (input operation)
mvwhline window
mvwhline_set window
mvwin window
mvwin_wch window
mvwin_wchnstr window
mvwin_wchstr window
mvwinch window
mvwinchnstr window
mvwinchstr window
mvwinnstr window
mvwinnwstr window
mvwins_nwstr window
mvwins_wch window
mvwins_wstr window
mvwinsch window
mvwinsnstr window
mvwinsstr window
mvwinstr window
mvwinwstr window
mvwprintw window
mvwscanw screen
mvwvline window
mvwvline_set window
napms reentrant
newpad global (locks window list)
newscr screen (read-only)
newterm global (locks screen list)
newwin global (locks window list)
nl screen
nocbreak screen
nodelay window
noecho screen
nofilter global
nonl screen
noqiflush terminal
noraw screen
notimeout window
numcodes global (read-only)
numfnames global (read-only)
numnames global (read-only)
ospeed global
overlay window (locks source, target)
overwrite window (locks source, target)
pair_content screen
pecho_wchar screen
pechochar screen
pnoutrefresh screen
prefresh screen
printw window
putp global
putwin window
qiflush terminal
raw screen
redrawwin window
refresh screen
reset_prog_mode screen
reset_shell_mode screen
resetty terminal
resize_term screen (locks window list)
resizeterm screen
restartterm screen
ripoffline global (static data)
savetty terminal
scanw screen
scr_dump screen
scr_init screen
scr_restore screen
scr_set screen
scrl window (stdscr)
scroll window
scrollok window
set_curterm screen
set_escdelay screen
set_tabsize screen
set_term global (locks screen list, screen)
setcchar reentrant
setscrreg window (stdscr)
setupterm global
slk_attr screen
slk_attr_off screen
slk_attr_on screen
slk_attr_set screen
slk_attroff screen
slk_attron screen
slk_attrset screen
slk_clear screen
slk_color screen
slk_init screen
slk_label screen
slk_noutrefresh screen
slk_refresh screen
slk_restore screen
slk_set screen
slk_touch screen
slk_wset screen
standend window
standout window
start_color screen
stdscr screen (read-only)
strcodes global (read-only)
strfnames global (read-only)
strnames global (read-only)
subpad window
subwin window
syncok window
term_attrs screen
termattrs screen
termname terminal
tgetent global
tgetflag global
tgetnum global
tgetstr global
tgoto global
tigetflag terminal
tigetnum terminal
tigetstr terminal
timeout window (stdscr)
touchline window
touchwin window
tparm global (static data)
tputs screen
trace global (static data)
ttytype screen (read-only)
typeahead screen
unctrl screen
unget_wch screen (input operation)
ungetch screen (input operation)
ungetmouse screen (input operation)
untouchwin window
use_default_colors screen
use_env global (static data)
use_extended_names global (static data)
use_legacy_coding screen
use_screen global (locks screen list, screen)
use_window global (locks window list, window)
vid_attr screen
vid_puts screen
vidattr screen
vidputs screen
vline window (stdscr)
vline_set window (stdscr)
vw_printw window
vw_scanw screen
vwprintw window
vwscanw screen
wadd_wch window
wadd_wchnstr window
wadd_wchstr window
waddch window
waddchnstr window
waddchstr window
waddnstr window
waddnwstr window
waddstr window
waddwstr window
wattr_get window
wattr_off window
wattr_on window
wattr_set window
wattroff window
wattron window
wattrset window
wbkgd window
wbkgdset window
wbkgrnd window
wbkgrndset window
wborder window
wborder_set window
wchgat window
wclear window
wclrtobot window
wclrtoeol window
wcolor_set window
wcursyncup screen (affects window plus parents)
wdelch window
wdeleteln window
wecho_wchar window
wechochar window
wenclose window
werase window
wget_wch screen (input operation)
wget_wstr screen (input operation)
wgetbkgrnd window
wgetch screen (input operation)
wgetdelay window
wgetn_wstr screen (input operation)
wgetnstr screen (input operation)
wgetparent window
wgetscrreg window
wgetstr screen (input operation)
whline window
whline_set window
win_wch window
win_wchnstr window
win_wchstr window
winch window
winchnstr window
winchstr window
winnstr window
winnwstr window
wins_nwstr window
wins_wch window
wins_wstr window
winsch window
winsdelln window
winsertln window
winsnstr window
winsstr window
winstr window
winwstr window
wmouse_trafo window
wmove window
wnoutrefresh screen
wprintw window
wredrawln window
wrefresh screen
wresize window (locks window list)
wscanw screen
wscrl window
wsetscrreg window
wstandend window
wstandout window
wsyncdown screen (affects window plus parents)
wsyncup screen (affects window plus parents)
wtimeout window
wtouchln window
wunctrl global (static data)
wvline window
wvline_set window

get_escdelay returns the value of ESCDELAY. set_escdelay and set_tabsize return ERR upon failure and OK upon successful completion. use_screen and use_window return the int returned by the user-supplied function they are called with.

ncurses provides both a C function and a preprocessor macro for each function documented in this page.

These routines are specific to ncurses. They were not supported on Version 7, BSD or System V implementations. It is recommended that any code depending on ncurses extensions be conditioned using NCURSES_VERSION.

curses(3X), curs_opaque(3X), curs_variables(3X)

2024-03-16 ncurses 6.5