CSE 20232 Lecture 11 – Ncurses I/O

1. CSE 20232Lecture 11 – Ncurses I/O • Ncurses I/O • text-based GUI • Simple Program • Setting Up & Shutting Down • Moving cursor & handling I/O • Color (only on some terminals) • Special Keys • The Mouse

2. Curses Library • Allows “text-based” GUI • Curses or Ncurses for Unix/Linux/AIX • Defined in “curses.h” header file • PDCurses (Public Domain Curses) for Dos/Windows • Supports mouse, keypads, color, buffered & non-buffered input, and some simple graphics (lines, boxes, etc)

3. Curses (Windows, etc) • Curses works by creating a window / screen / console data structure within which the program moves the cursor and performs output • A refresh() function updates the actual window / screen / console to reflect the logical one • See class web site for URLs of Curses resources / tutorials / examples/ etc.

4. Curses Basics – Hello World! #include<curses.h> int main() { // always do this first initscr(); // initialize curses // these are optional cbreak(); // input keys immediately available noecho(); // stop echoing inputs nonl(); // faster cursor movement clear(); // clear the screen // move cursor to location and output message // upper left screen corner is 0,0 move(12,5); // move cursor to row 12, column 5 printw(“Hello World\n”); // instead of cout << ... refresh(); // make it visible to us getch(); // wait for a key to be hit endwin(); // release window back to shell return 0; }

5. CursesInitialization & Shutdown • Must use … • initscr();// first, to initialize curses • endwin();// last, to return screen to normal • Probably use … • cbreak();// enable direct keystroke access • noecho();// prevent echoing of input • nonl();// speeds cursor movement • getmaxyx(stdscr,h,w);// get screen limits • Notes: • stdscris the default screen/window

6. CursesMoving cursor & I/O • Cursor & position • move(y,x);// move cursor to line y, char posit x • Upper left of screen is at position 0,0 • getyx(y,x);// returns current cursor location • I/O • printw(“%d %s”, num, str);// cout << • Parameters are same as printf() • Prints in window from current cursor location • scanw(“%f”,&realNum);// cin >> • Parameters are same as scanf() • Reads input stream as directed by format string • getch();// reads single keystroke • wgetch(stdscr);// reads single keystroke • From indicated window

7. CursesMoving cursor & I/O • Combined movement and I/O • mvprintw(y,x,“%d %s”, num, str); • Prints in window from cursor location y, x • mvscanw(y,x,“%f”,&realNum); • Reads input stream as directed by format string • Making it visible • refresh();// updates console • Makes it match logical window data structure

8. Curses Color • Only supported on certain terminal types • xterm is good bet • set term=xterm • at unix prompt before running program • start_color();// initializes color • init_pair(num,fg_color,bg_color); • Creates a COLOR_PAIR of foreground and background colors • xterm has 8 colors and 64 color pairs, max • attron(COLOR_PAIR(num)); • makes color pair the output attribute until turned off • attroff(COLOR_PAIR(num));

9. Curses COLORS • COLOR_BLACK • COLOR_RED • COLOR_GREEN • COLOR_YELLOW • COLOR_BLUE • COLOR_MAGENTA • COLOR_CYAN • COLOR_WHITE

10. Curses Using Special Keys • To use function keys, arrows, etc. Initialize with • keypad(stdscr,TRUE); • Must be used before both special key input • And before mouse event capture • prevents immediate translation to ASCII • Get key with • int key = getch(); • Test key with keycodes • KEY_DOWN, KEY_UP, KEY_LEFT, KEY_RIGHT • KEY_HOME, KEY_BACKSPACE • KEY_F(n) Function keys, for 0 <= n >= 63 • KEY_DC Delete character • KEY_IC Insert char or enter insert mode • KEY_ENTER Enter or send

11. Curses Mouse Support • Only in Ncurses (Linux & AIX) • Initialize for capture of events with • mousemask(ALL_MOUSE_EVENTS,NULL); • Specific masks (BUTTON1_CLICKED, ...) • Read mouse click with • int key = getch(); or • int key =wgetch(stdscr);

12. Curses Mouse Events • Processing event • Value read will equal KEY_MOUSE • Use getmouse(&event) to recover event from event queue • Use event.bstate to determine button state (which event) • Use event.x and event.y to determine where mouse was clicked in window MEVENT event;// data type for mouse event if (key == KEY_MOUSE)// if it was the mouse if (getmouse(&event) == OK) { // get the event if (event.bstate & BUTTON1_CLICKED) { // so do something with // event.y; and event.x;

13. Example Curses Programs(on class web site) • hi.cpp • Simple curses “Hello World” program • bigHi.cpp • Shows big “HI” on screen • hw4_sample.cpp • Shows size of curses window, once open • mvbox.cpp • Moving star shape: Uses keyboard (letter) inputs • mvbox2.cpp • Moving star and box shapes: Uses keyboard (letter) inputs • Mvbox3.cpp • Like mvbox2.cpp but also uses arrow keys and mouse • tttCM (executable only) • TicTacToe: Uses Color, mouse and keyboard inputs

14. Finis • Look at some sample Ncurses Programs • Answer questions on any topic • Adios