#include <qapplication.h>
#include <qcanvas.h>
#include <stdlib.h>

class Logo : public QCanvasSprite {
    void initPos() {
	initSpeed();
	int trial=1000;
	do {
	    move(rand()%(canvas()->width()-width()),rand()%(canvas()->height()-height()));
	    advance(0);
	} while (trial-- && xVelocity()==0.0 && yVelocity()==0.0);
    }
    void initSpeed() {
	const double speed = 4.0;
	double d = (double)(rand()%1024) / 1024.0;
	setVelocity( d*speed*2-speed, (1-d)*speed*2-speed );
    }
public:
    Logo( QCanvasPixmapArray* pm,  QCanvas* c ) : QCanvasSprite( pm, c ) {
	setAnimated(TRUE);
	initPos();
    }
    void advance( int stage ) {
	switch ( stage ) {
	case 0: {
	    double vx = xVelocity();
	    double vy = yVelocity();

	    // we are too slow, reinitialize speed
	    if ( QABS( vx ) < 0.1 && QABS(vy) < 0.1 ) {
		initSpeed();
		vx = xVelocity();
		vy = yVelocity();
	    }

	    // whenever we hit a wall, turn around
 	    if ( x()+vx < 0 || x()+width()+vx >= canvas()->width() )
 		vx = -vx;
 	    if ( y()+vy < 0 || y()+height()+vy >= canvas()->height() )
 		vy = -vy;

	    // test all four directions and bounce if possible. If
	    // not, slow down
	    for (int bounce=0; bounce<4; bounce++) {
		QCanvasItemList l=collisions(FALSE);
		for (QCanvasItemList::Iterator it=l.begin(); it!=l.end(); ++it) {
		    if ( (*it)->collidesWith(this) ) {
			switch ( bounce ) {
			case 0: vx = -vx; break;
			case 1: vy = -vy; vx = -vx; break;
			case 2: vx = -vx; break;
 			case 3: vx /= 2; vy /= 2; break;
			}
			setVelocity(vx,vy);
			break;
		    }
		}
	    }

	    // we still would hit a wall, slow down speed
 	    if ( x()+vx < 0 || x()+width()+vx >= canvas()->width() )
 		vx /= 2;
 	    if ( y()+vy < 0 || y()+height()+vy >= canvas()->height() )
 		vy /= 2;

	    setVelocity(vx,vy);
	} break;
	case 1:
	    QCanvasItem::advance(stage);
	    break;
	}
    }
};


int main( int argc, char* argv[] )
{
    QApplication a( argc, argv );
    QCanvas canvas( 800, 600 );

    QCanvasPixmapArray pm("qtlogo.png" );

    for ( int i = 0; i < 6; i++ )
	(new Logo( &pm, &canvas ) )->show();

    canvas.setAdvancePeriod(30);

    QCanvasView cview( &canvas );
    a.setMainWidget( &cview );
    cview.setCaption( "Bouncing Qt logos");
    cview.show();
    return a.exec();
}