curs_threads(3X) curs_threads(3X)


use_screen, use_window - curses thread support


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


This implementation can be configured to provide rudimentary support for multi-threaded applications. This makes a different set of libraries, e.g., libncursest since the binary interfaces are different.

Rather than modify the interfaces to pass a thread specifier to each function, it adds a few functions which can be used in any configuration which hide the mutex's needed to prevent concurrent use of the global variables when configured for threading.

In addition to forcing access to members of the WINDOW structure to be via functions (see curs_opaque(3x)), it makes functions of the common global variables, e.g., COLORS, COLOR_PAIRS, COLS, ESCDELAY, LINES, TABSIZE curscr, newscr and ttytype. Those variables are maintained as read-only values, stored in the SCREEN structure.

Even this is not enough to make a thread-safe application using curses. A multi-threaded application would be expected to have threads updating separate windows (within the same device), or updating on separate screens (on different devices). Also, a few of the global variables are considered writable by some applications. 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.

The use_window and use_screen functions provide coarse granularity mutexes for their respective WINDOW and SCREEN parameters, and call a user-supplied function, passing it a data parameter, and returning the value from the user-supplied function to the application.


All of the ncurses library functions assume that the locale is not altered during operation. In addition, they use data which is maintained within a hierarchy of scopes.
global data, e.g., used in the low-level terminfo or termcap interfaces.
terminal data, e.g., associated with a call to set_curterm. The terminal data are initialized when screens are created.
screen data, e.g., associated with a call to newterm or initscr.
window data, e.g., associated with a call to newwin or subwin. Windows are associated with screens. Pads are not necessarily associated with a particular screen.
Most curses applications operate on one or more windows within a single screen.
reentrant, i.e., it uses only the data passed as parameters.

This table lists the scope of data used for each symbol in the ncurses library when it is configured to support threading:

Symbol Scope
BC global
COLORS screen (readonly)
COLOR_PAIR reentrant
COLOR_PAIRS screen (readonly)
COLS screen (readonly)
ESCDELAY screen (readonly, see set_escdelay)
LINES screen (readonly)
PAIR_NUMBER reentrant
PC global
SP global
TABSIZE screen (readonly)
UP global
acs_map screen (readonly)
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 (readonly)
boolfnames global (readonly)
boolnames global (readonly)
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 (readonly)
curses_version global (readonly)
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(screenlist, screen)
delwin global locks(windowlist)
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(screenlist)
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(windowlist)
newscr screen (readonly)
newterm global locks(screenlist)
newwin global locks(windowlist)
nl screen
nocbreak screen
nodelay window
noecho screen
nofilter global
nonl screen
noqiflush terminal
noraw screen
notimeout window
numcodes global (readonly)
numfnames global (readonly)
numnames global (readonly)
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(windowlist)
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(screenlist, 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 (readonly)
strcodes global (readonly)
strfnames global (readonly)
strnames global (readonly)
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 (readonly)
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(screenlist, screen)
use_window global locks(windowlist, 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)
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(windowlist)
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


These functions all return TRUE or FALSE, except as noted.


Both a macro and a function are provided for each name.


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)