//Mandelbrot.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Mandelbrot extends JApplet implements ActionListener {
    
    private JLabel startRealLabel;
    private JTextField startRealField;
    private JLabel endRealLabel;
    private JTextField endRealField;

    private JLabel startImagLabel;
    private JTextField startImagField;
    private JLabel endImagLabel;
    private JTextField endImagField;

    private JLabel stepsLabel;
    private JTextField stepsField;

    private JLabel maxItsLabel;
    private JTextField maxItsField;

    private JButton doitButton;

    private JLabel zoomLabel;
    private JTextField zoomField;

    private JPanel topPanel;

    int xcenter, ycenter;  //needed by mouse event methods
    double scale;
    double originalZoom;


    public void init() {

      Container container = getContentPane();  
      //      container.setLayout( new BorderLayout() ); 

      topPanel = new JPanel();
      topPanel.setLayout( new GridLayout(3,6));

      startRealLabel = new JLabel( "Start real" );
      startRealField = new JTextField( 6 );
      startRealField.setText("-2.0");
      topPanel.add( startRealLabel );
      topPanel.add( startRealField );

      endRealLabel = new JLabel( "End real" );
      endRealField = new JTextField( 6 );
      endRealField.setText("1.0");
      topPanel.add( endRealLabel );
      topPanel.add( endRealField );

      startImagLabel = new JLabel( "Start imaginary" );
      startImagField = new JTextField( 6 );
      startImagField.setText("-1.0");
      topPanel.add( startImagLabel );
      topPanel.add( startImagField );

      endImagLabel = new JLabel( "End imaginary" );
      endImagField = new JTextField( 6 );
      endImagField.setText("1.0");
      topPanel.add( endImagLabel );
      topPanel.add( endImagField );

      stepsLabel = new JLabel( "Increments" );
      stepsField = new JTextField( 6 );
      stepsField.setText("1000");
      topPanel.add( stepsLabel );
      topPanel.add( stepsField );

      maxItsLabel = new JLabel( "Max iterations" );
      maxItsField = new JTextField( 6 );
      maxItsField.setText("100");
      topPanel.add( maxItsLabel );
      topPanel.add( maxItsField );

      doitButton = new JButton( "Do it" );
      topPanel.add( doitButton );

      doitButton.addActionListener( this );

      zoomLabel = new JLabel( "Zoom factor" );
      zoomField = new JTextField( 6 );
      zoomField.setEditable( false );
      zoomField.setText("1");
      topPanel.add( zoomLabel );
      topPanel.add( zoomField );

      originalZoom = Double.parseDouble(endRealField.getText()) -
	  Double.parseDouble(startRealField.getText());


      container.add( topPanel, BorderLayout.SOUTH);

      addMouseMotionListener(
	  //anonymous inner class overrides mouseMoved
	  new MouseMotionAdapter() {

	      public void mouseMoved( MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );

		  showStatus("move "+x + ", " + y + " --> " + r + ", " + imag);
	      }

	      public void mouseDragged( MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );

		  showStatus("drag " + x + ", " + y + " --> " + r + ", " + imag);
	      }
	  }
      );

      addMouseListener (
          new MouseAdapter() {
	      public void mousePressed (MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );

		  startRealField.setText ("" + r);
		  startImagField.setText ("" + imag);

	      }

	      public void mouseReleased (MouseEvent event) {
		  int x = event.getX();
		  int y = event.getY();
		  double r =  getR( x );
		  double imag = getImag( y );

		  endRealField.setText ("" + r);
		  endImagField.setText ("" + imag);

		  repaint();
	      }
	  }
       );


    }


    public void actionPerformed( ActionEvent event ) {
	if ( event.getSource() == doitButton )
	    repaint();
    }


    private double getR (int x ) {
	double start_real = Double.parseDouble(startRealField.getText());

	return x / scale + start_real;
    }

    private double getImag (int y ) {
	double start_imag = Double.parseDouble(startImagField.getText());

	return y / scale + start_imag;
    }

    public void paint( Graphics g )
    {
       super.paint( g );

       int   its, max_its, steps;
       int x1, y1;
       int appletSize;
       double start_real, end_real, inc_real, start_imag, end_imag, inc_imag;
       double zr, zi, t;

       start_real = Double.parseDouble(startRealField.getText());
       end_real =   Double.parseDouble(endRealField.getText());
       start_imag = Double.parseDouble(startImagField.getText());
       end_imag =   Double.parseDouble(endImagField.getText());
       steps =      Integer.parseInt(stepsField.getText());
       max_its =    Integer.parseInt(maxItsField.getText());

       inc_real = (end_real - start_real) / steps;
       inc_imag = (end_imag - start_imag) / steps;

       double dist_real = Math.abs(end_real - start_real);
       double dist_imag = Math.abs(end_imag - start_imag);
       double mid_real = start_real + dist_real/2;
       double mid_imag = start_imag + dist_imag/2;

       zoomField.setText("" + originalZoom/dist_real);

       appletSize = Math.min(getWidth(),getHeight());
       //double xScale = appletSize / dist_real;
       double xScale = getWidth() / dist_real;
       //double yScale = appletSize / dist_imag;
       double yScale = getHeight() / dist_imag;
       scale = Math.min(yScale,xScale);

       //xcenter = appletSize / 2;
       //ycenter = appletSize / 2 + 40;


       for (double r=start_real; r<end_real; r+=inc_real)
	   for (double imag=start_imag; imag<end_imag; imag+=inc_imag) {
	       zr = 0;
	       zi = 0;
	       its = 0;
	       while (its<max_its && zr*zr+zi*zi<4) {
		   t = zr*zr - zi*zi + r;
		   zi = 2*zr*zi + imag;
		   zr = t;
		   its++;
	       }
	       if (its == max_its) {
		   //x1 = (int)(r * appletSize + xcenter);
		   //y1 = (int)(imag * appletSize + ycenter);
		   //x1 = (int)((r    - start_real) * scale + xcenter);
		   //y1 = (int)((imag - start_imag) * scale + ycenter);
		   //x1 = (int)(r    * scale + xcenter);
		   //y1 = (int)(imag * scale + ycenter);
		   x1 = (int)(Math.abs(r -  start_real) * scale);
		   y1 = (int)(Math.abs(imag-start_imag) * scale);

		   g.setColor( Color.BLACK );
		   g.drawLine(x1,y1,x1,y1);  //point
	       }
	       else {
		   g.setColor( new Color( 128+(int)((double)its/max_its*128),0,0));
		   x1 = (int)(Math.abs(r -  start_real) * scale);
		   y1 = (int)(Math.abs(imag-start_imag) * scale);

		   g.drawLine(x1,y1,x1,y1);  //point
	       }
	   }
    }
}