CURSES_SCREEN(3)

NAME
curses_screen, filter, ripoffline, use_env, newterm, set_term, delscreen, endwin, initscr, isendwin, is_term_resized, resize_term, resizeterm, setterm, set_tabsize - curses terminal and screen routines

LIBRARY
libcurses

SYNOPSIS
#include <curses.h>
void
filter(void);
int
ripoffline(int line, int (*init)(WINDOW *win, int cols));
void
use_env(bool value);
SCREEN *
newterm(char *type, FILE *outfd, FILE *infd);
SCREEN *
set_term(SCREEN *screen);
void
delscreen(SCREEN *screen);
int
endwin(void);
WINDOW *
initscr(void);
bool
isendwin(void);
bool
is_term_resized(int lines, int cols);
int
resize_term(int lines, int cols);
int
resizeterm(int lines, int cols);
int
setterm(char *name);
int
set_tabsize(int value);

extern int LINES;

extern int COLS;

DESCRIPTION
These functions initialize terminals and screens.

The newterm() function initialises the curses data structures and pointers ready for use by curses. The type argument points to a terminfo(5) entry, or it may be NULL in which case the TERM environment variable is used. The outfd and infd are the output and input file descriptors for the terminal. The newterm() function must only be called once per terminal.

The set_term() function can be used to switch between the screens defined by calling newterm(), a pointer to the previous screen structure that was in use will be returned on success.

Calling delscreen() will destroy the given screen and free all allocated resources.

Calling endwin() will end the curses session and restore the saved terminal settings.

The curses session must be initialised by calling initscr() which saves the current terminal state and sets up the terminal and internal data structures to support the curses application. This function call must be, with few exceptions, the first Curses library call made. The exception to this rule is the newterm() call which may be called prior to initscr(). The size of the curses screen is determined by checking the tty(4) size and then the terminfo(5) entries for the terminal type. If the environment variables LINES or COLUMNS are set, then these will be used instead.

When either newterm() or initscr() are called, the Curses library sets up signal handlers for SIGTSTP and SIGWINCH. If a signal handler is already installed for SIGWINCH, this will also be called when the Curses library handler is called.

The isendwin() function can be used to determine whether or not a refresh of the screen has occurred since the last call to endwin().

The size of the screen may be changed by calling resize_term() with the updated number of lines and columns. This will resize the curses internal data structures to accommodate the changed terminal geometry. The curscr and stdscr windows and any of their subwindows will be resized to fit the new screen size. The application must redraw the screen after a call to resize_term(). The resizeterm() function is a wrapper for resize_term() and adjusts other structure data that handles window dimensions. The is_term_resized() function tests if either of the above functions need to be called.

The setterm() function sets the terminal type for the current screen to the one passed, initialising all the curses internal data structures with information related to the named terminal. The name argument must be a valid name or alias in the terminfo(5) database for this function to succeed.

The filter() function changes the way the terminal is initialised. A subsequent call to initscr() or newterm() performs the following additional actions:
•   Disable use of clear, cud, cud1, cup, cuu, cuu1 and vpa.
•   Set the value of the home string to the value of the cr string.
•   Set lines equal to 1.

The ripoffline() function will rip a line from stdscr at the top if line is positive, or at the bottom if negative. When initscr() or newterm() is called, a window will be created for each line ripped and passed to the init function pointer alongwith the number of columns in the window. This init function cannot use the LINES or COLS variables and cannot call wrefresh(3) or doupdate(3), but may call wnoutrefresh(3). ripoffline() can be called up to five times.

The use_env() function determines whether the environment variables LINES and COLUMNS override the normal values. The default is true. Any call to use_env() must precede calls to initscr(), newterm(), or setupterm().

The set_tabsize() function will set TABSIZE of the current screen to tabsize.

RETURN VALUES
Functions returning pointers will return NULL if an error is detected with the exception of initscr() which will log a diagnostic to standard error output and then call exit(3). The functions that return an int will return one of the following values:

OK  The function completed successfully.
ERR An error occurred in the function.

SEE ALSO
curses_window(3), tty(4), terminfo(5), signal(7)

STANDARDS
The NetBSD Curses library complies with the X/Open Curses specification, part of the Single Unix Specification.

HISTORY
The Curses package appeared in 4.0BSD. The resizeterm() function is an ncurses extension to the Curses library and was added in NetBSD 1.6. The is_term_resized(), resize_term() and set_tabsize() functions are ncurses extensions to the Curses library and were added in NetBSD 8.0.

BUGS
There is currently an issue with cursor movement in a 1 line sized window which causes the screen to scroll up. This can obviously be seen when using ripoffline().