#include <qapplication.h>
#include <qwidget.h>
#include <qpainter.h>
#include <qpixmap.h>
#include <qtimer.h>
#include <cmath>
#include <vector>  // vector headers
#include <iostream>
using namespace std;

class Ball {
private:
  Ball();
  QPoint ballpos;
  double angle, dangle;
  int ballradius, dist;
  const Ball *refball;

public:
  Ball(int x, int y, int rad);
  Ball(const Ball *bref, int dist, int rad, double dang);
  Ball(const QPoint &);
  virtual void travel(double time);
  void paint(QPainter &painter) const;

};

Ball::Ball(int x, int y, int rad) : refball(0)
{
  ballpos.setX(x);
  ballpos.setY(y);
  ballradius = rad;
  
  dist = 0;
  angle = 0.;
  dangle = 0.;
}

Ball::Ball(const Ball *bref, int d, int rad, double dang) : refball( bref)
{
  ballpos.setX(refball->ballpos.x());
  ballpos.setY(refball->ballpos.y()+d);

  dist = d;
  ballradius = rad;
  angle = 0.;
  dangle  = dang;
}


void Ball::paint(QPainter &painter) const 
{
  painter.drawEllipse( ballpos.x()-ballradius/2, 
			     ballpos.y()-ballradius/2, ballradius, ballradius );
}

void Ball::travel(double time) {
  
  if ( dangle != 0. ) {
    angle += time*dangle;  // change angle
    if ( angle > 360. ) angle -= 360.;
    //    angle %= 360;         // modulo 360
    int x = refball->ballpos.x() // - refball->ballradius
      +  (int) (cos( angle*M_PI/180.) * dist);
    int y = refball->ballpos.y() // - refball->ballradius
      +  (int) (sin( angle*M_PI/180.) * dist);
    ballpos.setX(x);
    ballpos.setY(y);
  }
}
class PlanetAnim : public QWidget
{
  Q_OBJECT
public:
  PlanetAnim();

protected:
  virtual void paintEvent(QPaintEvent*);
private slots:
  virtual void timeout(  );
private:
  int xpos, ypos, radius; // sun parameters
  int xpose, ypose, radiuse; // earth parameters


  vector<Ball*> vb;

  int distsunearth, deltaAngle, currentAngle;

  QColor mycol;
};

PlanetAnim::PlanetAnim()
{

  Ball *sun   = new Ball( 250, 250, 60 );
  Ball *earth = new Ball( sun, 200, 15, 1. );
  Ball *moon  = new Ball( earth, 25, 6, 10. );

  vb.push_back( sun );
  vb.push_back( earth );
  vb.push_back( moon );

  mycol = Qt::yellow;
  setBackgroundRole(QPalette::Base);
  setAutoFillBackground(true);

  // setup timer
  QTimer *internalTimer = new QTimer( this ); // create internal timer
  connect( internalTimer, SIGNAL(timeout()), this, SLOT(timeout()) );
  internalTimer->start(50 );               // emit signal every 100 ms
}


void PlanetAnim::timeout()
{
  for ( int i= 0; i<vb.size(); i++ ) {
    vb[i]->travel( 2. );
  }
  update();
}

void PlanetAnim::paintEvent(QPaintEvent *)
{
  QPainter paint;
  paint.begin( this);  

  paint.setPen( Qt::red );
  paint.setBrush( Qt::red );

  for ( int i= 0; i<vb.size(); i++ ) {
    vb[i]->paint( paint );
  }

  paint.end();
}

#include "PlanetAnim.moc"

int main(int argc, char **argv)
{
    QApplication app(argc,argv);

    PlanetAnim *wid = new PlanetAnim();
    wid->resize(500,500);
    wid->show();
    return app.exec();
}