CURSES_SCREEN(3)

CURSES_SCREEN(3) | Library Functions Manual | 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

Curses Library (libcurses, -lcurses)

# 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 additonal 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. 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 a 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 extension to the Curses library and was 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`().

October 2, 2018 | NetBSD 9.5