#include	<stdio.h>
#include	<curses.h>
#include	<signal.h>

/*
 * bounce0.c
 *	purpose	animation with user control
 *	note	alarm() sends SIGALRM, handler does animation
 *		keyboard waits for input
 *	compile	cc bounce0.c -lcurses -o bounce0
 */

/*
 * some global vars that main and the handler use
 */

#define	MESSAGE	" hello "

int	row;	/* current row		*/
int	col;	/* current column	*/
int	dir;	/* where we are going	*/
int	delay;	/* how long to wait	*/

main()
{
	void	on_alarm(int);	/* handler for alarm	*/
	int	c;		/* user input		*/

	initscr();
	crmode();
	noecho();
	clear();

	row   = 10;		/* start here		*/
	col   = 0;
	dir   = 1;		/* add 1 to row number	*/
	delay = 1;		/* 1 sec between moves	*/

	move(row,col);		/* get into position	*/
	addstr( MESSAGE );	/* note spaces		*/
	signal(SIGALRM, on_alarm );
	alarm(delay);

	while(1)
	{
		c = getch();
		if ( c == 'Q' ) break;
		if ( c == ' ' ) dir = -dir;
	}
	endwin();
}

void on_alarm(int signum)
{
	signal(SIGALRM, on_alarm);	/* reset, just in case	*/
	col += dir;			/* move to new column	*/
	move( row, col );		/* then set cursor	*/
	addstr( MESSAGE );		/* redo message		*/
	refresh();			/* and show it		*/

	/*
	 * now handle borders
	 */
	if ( dir == -1 && col == 0 )
		dir = 1;
	else if ( dir == 1 && col+strlen(MESSAGE) >= COLS )
		dir = -1;
	alarm(delay);
}