Copyright (c) 1980 The Regents of the University of California.
All rights reserved.
%sccs.include.redist.roff%
@(#)intro.3 6.8 (Berkeley) 02/03/93
.sh 1 Usage .pp This is a description of how to actually use the screen package. For simplicity, we assume all updating, reading, etc. is applied to .Vn stdscr , although a different window can of course be specified. .sh 2 "Initialization" .pp In order to use the screen package, the routines must know about terminal characteristics, and the space for .Vn curscr and .Vn stdscr must be allocated. These functions are performed by .Fn initscr . Since it must allocate space for the windows, it can overflow core when attempting to do so. On this rather rare occasion, .Fn initscr returns ERR. .Fn Initscr must .bi always be called before any of the routines which affect windows are used. If it is not, the program will core dump as soon as either .Vn curscr or .Vn stdscr are referenced. However, it is usually best to wait to call it until after you are sure you will need it, like after checking for startup errors. Terminal status changing routines like .Fn nl and .Fn cbreak should be called after .Fn initscr . .pp After the initial window allocation done by .Fn initscr , specific window characteristics can be set. Scrolling can be enabled by calling .Fn scrollok . If you want the cursor to be left after the last change, use .Fn leaveok . If this isn't done, .Fn refresh will move the cursor to the window's current \*y after updating it. Additional windows can be created by using the functions .Fn newwin and .Fn subwin . .Fn Delwin allows you to delete an exisiting window. The variables .Vn LINES and .Vn COLS control the size of the terminal. They are initially implicitly set by .Fn initscr , but can be altered explicitly by the user followed by a call to .Fn initscr . Note that any call to .Fn initscr , will always delete any existing .Vn stdscr and/or .Vn curscr before creating new ones so this change is best done before the initial call to .Fn initscr . .pp .sh 2 "Output" .pp The basic functions used to change what will go on a window are .Fn addch and .Fn move . .Fn Addch adds a character at the current \*y, returning ERR if it would cause the window to illegally scroll, .i i.e. , printing a character in the lower right-hand corner of a terminal which automatically scrolls if scrolling is not allowed. .Fn Move changes the current \*y to whatever you want them to be. It returns ERR if you try to move off the window. As mentioned above, you can combine the two into .Fn mvaddch to do both things in one call. .pp The other output functions (such as .Fn addstr and .Fn printw ) all call .Fn addch to add characters to the window. .pp After a change has been made to the window, you must call .Fn refresh . when you want the portion of the terminal covered by the window to reflect the change. In order to optimize finding changes, .Fn refresh assumes that any part of the window not changed since the last .Fn refresh of that window has not been changed on the terminal, .i i.e. , that you have not refreshed a portion of the terminal with an overlapping window. If this is not the case, the routines .Fn touchwin , .Fn touchline , and .Fn touchoverlap are provided to make it look like a desired part of window has been changed, thus forcing .Fn refresh to check that whole subsection of the terminal for changes. .pp If you call .Fn wrefresh with .Vn curscr , it will make the screen look like the image of .Vn curscr . This is useful for implementing a command which would redraw the screen in case it got messed up. .sh 2 Input .pp Input is essentially a mirror image of output. The complementary function to .Fn addch is .Fn getch which, if echo is set, will call .Fn addch to echo the character. Since the screen package needs to know what is on the terminal at all times, if characters are to be echoed, the tty must be in raw or cbreak mode. If it is not, .Fn getch sets it to be cbreak, and then reads in the character. .sh 2 "Termination" .pp In order to perform certain optimizations, and, on some terminals, to work at all, some things must be done before the screen routines start up. These functions are performed in .Fn getttmode and .Fn setterm , which are called by .Fn initscr . In order to clean up after the routines, the routine .Fn endwin is provided. It restores tty modes to what they were when .Fn initscr was first called. The terminal state module uses the variable .Vn curses_termios to save the original terminal state which is then restored upon a call to .Fn endwin . Thus, anytime after the call to initscr, .Fn endwin should be called before exiting. Note however, that .Fn endwin should always be called .b before the final calls to .Fn delwin , which free the storage of the windows.
All rights reserved.
%sccs.include.redist.roff%
@(#)intro.3 6.8 (Berkeley) 02/03/93
.sh 1 Usage .pp This is a description of how to actually use the screen package. For simplicity, we assume all updating, reading, etc. is applied to .Vn stdscr , although a different window can of course be specified. .sh 2 "Initialization" .pp In order to use the screen package, the routines must know about terminal characteristics, and the space for .Vn curscr and .Vn stdscr must be allocated. These functions are performed by .Fn initscr . Since it must allocate space for the windows, it can overflow core when attempting to do so. On this rather rare occasion, .Fn initscr returns ERR. .Fn Initscr must .bi always be called before any of the routines which affect windows are used. If it is not, the program will core dump as soon as either .Vn curscr or .Vn stdscr are referenced. However, it is usually best to wait to call it until after you are sure you will need it, like after checking for startup errors. Terminal status changing routines like .Fn nl and .Fn cbreak should be called after .Fn initscr . .pp After the initial window allocation done by .Fn initscr , specific window characteristics can be set. Scrolling can be enabled by calling .Fn scrollok . If you want the cursor to be left after the last change, use .Fn leaveok . If this isn't done, .Fn refresh will move the cursor to the window's current \*y after updating it. Additional windows can be created by using the functions .Fn newwin and .Fn subwin . .Fn Delwin allows you to delete an exisiting window. The variables .Vn LINES and .Vn COLS control the size of the terminal. They are initially implicitly set by .Fn initscr , but can be altered explicitly by the user followed by a call to .Fn initscr . Note that any call to .Fn initscr , will always delete any existing .Vn stdscr and/or .Vn curscr before creating new ones so this change is best done before the initial call to .Fn initscr . .pp .sh 2 "Output" .pp The basic functions used to change what will go on a window are .Fn addch and .Fn move . .Fn Addch adds a character at the current \*y, returning ERR if it would cause the window to illegally scroll, .i i.e. , printing a character in the lower right-hand corner of a terminal which automatically scrolls if scrolling is not allowed. .Fn Move changes the current \*y to whatever you want them to be. It returns ERR if you try to move off the window. As mentioned above, you can combine the two into .Fn mvaddch to do both things in one call. .pp The other output functions (such as .Fn addstr and .Fn printw ) all call .Fn addch to add characters to the window. .pp After a change has been made to the window, you must call .Fn refresh . when you want the portion of the terminal covered by the window to reflect the change. In order to optimize finding changes, .Fn refresh assumes that any part of the window not changed since the last .Fn refresh of that window has not been changed on the terminal, .i i.e. , that you have not refreshed a portion of the terminal with an overlapping window. If this is not the case, the routines .Fn touchwin , .Fn touchline , and .Fn touchoverlap are provided to make it look like a desired part of window has been changed, thus forcing .Fn refresh to check that whole subsection of the terminal for changes. .pp If you call .Fn wrefresh with .Vn curscr , it will make the screen look like the image of .Vn curscr . This is useful for implementing a command which would redraw the screen in case it got messed up. .sh 2 Input .pp Input is essentially a mirror image of output. The complementary function to .Fn addch is .Fn getch which, if echo is set, will call .Fn addch to echo the character. Since the screen package needs to know what is on the terminal at all times, if characters are to be echoed, the tty must be in raw or cbreak mode. If it is not, .Fn getch sets it to be cbreak, and then reads in the character. .sh 2 "Termination" .pp In order to perform certain optimizations, and, on some terminals, to work at all, some things must be done before the screen routines start up. These functions are performed in .Fn getttmode and .Fn setterm , which are called by .Fn initscr . In order to clean up after the routines, the routine .Fn endwin is provided. It restores tty modes to what they were when .Fn initscr was first called. The terminal state module uses the variable .Vn curses_termios to save the original terminal state which is then restored upon a call to .Fn endwin . Thus, anytime after the call to initscr, .Fn endwin should be called before exiting. Note however, that .Fn endwin should always be called .b before the final calls to .Fn delwin , which free the storage of the windows.