COLORS, COLOR_PAIRS, COLS, ESCDELAY, LINES,
TABSIZE, curscr, newscr, stdscr - curses
global variables
#include <ncurses/curses.h>
int COLOR_PAIRS;
int COLORS;
int COLS;
int ESCDELAY;
int LINES;
int TABSIZE;
WINDOW * curscr;
WINDOW * newscr;
WINDOW * stdscr;
This page summarizes variables provided by the curses library. A more
complete description is given in the curses(3X) manual page.
Depending on the configuration, these may be actual variables, or
macros (see curs_threads(3X) and curs_opaque(3X)) which
provide read-only access to curses's state. In either case,
applications should treat them as read-only to avoid confusing the
library.
After initializing curses, this variable contains the number of color pairs
which the terminal can support. Usually the number of color pairs will be the
product COLORS*COLORS, however this is not always true:
- a few terminals use HLS colors, which do not follow this rule
- terminals supporting a large number of colors are limited by the number of
color pairs that can be represented in a signed short value.
After initializing curses, this variable contains the number of colors which the
terminal can support.
After initializing curses, this variable contains the width of the screen, i.e.,
the number of columns.
This variable holds the number of milliseconds to wait after reading an escape
character, to distinguish between an individual escape character entered on
the keyboard from escape sequences sent by cursor- and function-keys (see
curses(3X)).
After initializing curses, this variable contains the height of the screen,
i.e., the number of lines.
This variable holds the number of columns used by the curses library when
converting a tab character to spaces as it adds the tab to a window (see
curs_addch(3X).
This implementation of curses uses a special window curscr to record its
updates to the terminal screen.
This is referred to as the “physical screen” in the
curs_refresh(3X) and curs_outopts(3X) manual pages.
This implementation of curses uses a special window newscr to hold
updates to the terminal screen before applying them to curscr.
This is referred to as the “virtual screen” in the
curs_kernel(3X), curs_refresh(3X) and curs_outopts(3X)
manual pages.
Upon initializing curses, a default window called stdscr, which is the
size of the terminal screen, is created. Many curses functions use this
window.
The curses library is initialized using either initscr(3X), or
newterm(3X).
If curses is configured to use separate curses/terminfo
libraries, most of these variables reside in the curses library.
TABSIZE is a feature of SVr4 curses which is not documented by X/Open
curses.
- •
- In SVr4 curses, TABSIZE is initially set from the terminal
description's init_tabs capability. After that, it can be altered
by the applications using SVr4 curses.
- SVr4 curses uses the current value of TABSIZE to compute the
position of tabstops for updating both the virtual screen with
addch(3X) as well as the physical screen with
mvcur(3X).
- This implementation uses the current value of TABSIZE only for
updating the virtual screen. It uses the terminal description's it
(init_tabs) capability for computing hardware tabs (i.e., tab stops
on the physical screen).
- Other implementations differ. For instance, NetBSD curses allows
TABSIZE to be set through an environment variable. This
implementation does not.
- NetBSD curses does not support hardware tabs; it uses the init_tabs
capability and the TABSIZE variable only for updating the virtual
screen.
ESCDELAY is an extension in AIX curses:
- In AIX, the units for ESCDELAY are fifths of a
millisecond.
- The default value for AIX's ESCDELAY is 0.1 seconds.
- AIX also enforces a limit of 10,000 seconds for ESCDELAY; this
implementation currently has no upper limit.
This implementation has long used ESCDELAY with units of
milliseconds, making it impossible to be completely compatible with AIX.
Likewise, most users have either decided to override the value, or rely upon
its default value.