.\" $NetBSD: curses_screen.3,v 1.23.4.1 2018/10/04 10:20:12 martin Exp $ .\" .\" Copyright (c) 2002 .\" Brett Lymn (blymn@NetBSD.org, brett_lymn@yahoo.com.au) .\" .\" This code is donated to the NetBSD Foundation by the Author. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the Author may not be used to endorse or promote .\" products derived from this software without specific prior written .\" permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" .Dd October 2, 2018 .Dt CURSES_SCREEN 3 .Os .Sh NAME .Nm curses_screen , .Nm filter , .Nm ripoffline , .Nm use_env , .Nm newterm , .Nm set_term , .Nm delscreen , .Nm endwin , .Nm initscr , .Nm isendwin , .Nm is_term_resized , .Nm resize_term , .Nm resizeterm , .Nm setterm , .Nm set_tabsize .Nd curses terminal and screen routines .Sh LIBRARY .Lb libcurses .Sh SYNOPSIS .In curses.h .Ft void .Fn filter "void" .Ft int .Fn ripoffline "int line" "int (*init)(WINDOW *win, int cols)" .Ft void .Fn use_env "bool value" .Ft SCREEN * .Fn newterm "char *type" "FILE *outfd" "FILE *infd" .Ft SCREEN * .Fn set_term "SCREEN *screen" .Ft void .Fn delscreen "SCREEN *screen" .Ft int .Fn endwin "void" .Ft WINDOW * .Fn initscr "void" .Ft bool .Fn isendwin "void" .Ft bool .Fn is_term_resized "int lines" "int cols" .Ft int .Fn resize_term "int lines" "int cols" .Ft int .Fn resizeterm "int lines" "int cols" .Ft int .Fn setterm "char *name" .Ft int .Fn set_tabsize "int value" .Pp .Va extern int LINES ; .Pp .Va extern int COLS ; .Sh DESCRIPTION These functions initialize terminals and screens. .Pp The .Fn newterm function initialises the curses data structures and pointers ready for use by curses. The .Fa type argument points to a .Xr terminfo 5 entry, or it may be .Dv NULL in which case the TERM environment variable is used. The .Fa outfd and .Fa infd are the output and input file descriptors for the terminal. The .Fn newterm function must only be called once per terminal. .Pp The .Fn set_term function can be used to switch between the screens defined by calling .Fn newterm , a pointer to the previous screen structure that was in use will be returned on success. .Pp Calling .Fn delscreen will destroy the given screen and free all allocated resources. .Pp Calling .Fn endwin will end the curses session and restore the saved terminal settings. .Pp The curses session must be initialised by calling .Fn 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 .Fn newterm call which may be called prior to .Fn initscr . The size of the curses screen is determined by checking the .Xr tty 4 size and then the .Xr terminfo 5 entries for the terminal type. If the environment variables .Ev LINES or .Ev COLUMNS are set, then these will be used instead. .Pp When either .Fn newterm or .Fn initscr are called, the Curses library sets up signal handlers for .Dv SIGTSTP and .Dv SIGWINCH . If a signal handler is already installed for .Dv SIGWINCH , this will also be called when the Curses library handler is called. .Pp The .Fn isendwin function can be used to determine whether or not a refresh of the screen has occurred since the last call to .Fn endwin . .Pp The size of the screen may be changed by calling .Fn 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 .Dv curscr and .Dv 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 .Fn resize_term . The .Fn resizeterm function is a wrapper for .Fn resize_term and adjusts other structure data that handles window dimensions. The .Fn is_term_resized function tests if either of the above functions need to be called. .Pp The .Fn 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 .Fa name argument must be a valid name or alias in the .Xr terminfo 5 database for this function to succeed. .Pp The .Fn filter function changes the way the terminal is initialised. A subsequent call to .Fn initscr or .Fn newterm performs the following additonal actions: .Bl -bullet -compact .It Disable use of clear, cud, cud1, cup, cuu, cuu1 and vpa. .It Set the value of the home string to the value of the cr string. .It Set lines equal to 1. .El .Pp The .Fn ripoffline function will rip a line from .Dv stdscr at the top if .Fa line is positive, or at the bottom if negative. When .Fn initscr or .Fn newterm is called, a window will be created for each line ripped and passed to the .Fa init function pointer alongwith the number of columns in the window. This init function cannot use the .Dv LINES or .Dv COLS variables and cannot call .Xr wrefresh 3 or .Xr doupdate 3 , but may call .Xr wnoutrefresh 3 . .Fn ripoffline can be called up to five times. .Pp The .Fn use_env function determines whether the environment variables .Ev LINES and .Ev COLUMNS override the normal values. The default is true. Any call to .Fn use_env must precede calls to .Fn initscr , .Fn newterm , or .Fn setupterm . .Pp The .Fn set_tabsize function will set .Va TABSIZE of the current screen to .Va tabsize . .Sh RETURN VALUES Functions returning pointers will return .Dv NULL if an error is detected. The functions that return an int will return one of the following values: .Pp .Bl -tag -width ERR -compact .It Er OK The function completed successfully. .It Er ERR An error occurred in the function. .El .Sh SEE ALSO .Xr curses_window 3 , .Xr tty 4 , .Xr terminfo 5 , .Xr signal 7 .Sh STANDARDS The .Nx Curses library complies with the X/Open Curses specification, part of the Single Unix Specification. .Sh HISTORY The Curses package appeared in .Bx 4.0 . The .Fn resizeterm function is a .Em ncurses extension to the Curses library and was added in .Nx 1.6 . The .Fn is_term_resized , .Fn resize_term and .Fn set_tabsize functions are .Em ncurses extension to the Curses library and was added in .Nx 8.0 . .Sh 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 .Fn ripoffline .