// plot_waved.java   a very basic, yet complete java plot application
//                  y=f(x)  x in 0.0 to 1.0, and y in -1.0 to 1.0
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Line2D;
import javax.swing.*;
    
public class plot_waved extends Frame
{
  int wsize = 1000;
  int xoff = 20; // frame
  int yoff = 60; // frame down
  int ymid = yoff+(wsize-xoff-yoff)/2;
  double xscale = (double)(wsize-xoff-xoff);
  double yscale = (double)(wsize-xoff-yoff);
  double xmin = 0.0;
  double xmax = 1.0;
  int nx = 512;
  double dx = (xmax-xmin)/(double)(nx-1);
  double x1, y1, x2, y2;
  int xp1, yp1, xp2, yp2;
    
  double f(double x) // y = f(x)  0.0 <= y <= 1.0
  {
    double y = 0.0;
    double r = 1.0;
    double Pi = Math.PI;
    r = 0.1+0.9*Math.cos(x*Pi);
    y = r*Math.cos(20.0*x*2.0*Pi);
    return y;
  } // end y
    
  plot_waved()
  {
    setTitle("plot_waved");
    setSize(wsize,wsize);
    setBackground(Color.white);
    setForeground(Color.black);
    addWindowListener(new WindowAdapter()
    {
      public void windowClosing(WindowEvent e)
      {
        System.exit(0);
      }
    });
    setVisible(true);
    this.addMouseListener (new mousePressHandler());
  }


  class mousePressHandler extends MouseAdapter
  {
    public void mousePressed (MouseEvent e)
    {
      requestFocus();
      System.out.println("press"); // debug print
      repaint();
      System.exit(0);
    }
  }

  public void paint(Graphics g)
  {
    g.drawString("r = 0.1+0.9*cos(x*Pi)     y = r*cos(20.0*x*2.0*Pi)",50,50);
    g.drawString("y=f(x)  xmin=0, xmax=1,    ymin=-1, ymax=1", wsize/2, 50);
    // draw boundary and y=0
    g.setColor(Color.red);
    g.drawRect(xoff, yoff, wsize-xoff-xoff, wsize-xoff-yoff);
    g.drawLine(xoff, ymid, wsize-xoff, ymid);
    g.setColor(Color.black);
    // draw a wave
    for(int i=0; i<nx-1; i++)
    {
      System.out.println("x1="+x1+"  y1=f(x1)="+f(x1));
      x1=xmin+dx*(double)i;
      y1 = (-f(x1)+1.0)/2.0; // y down, f(x) y=-1.0 to +1.0
      x2 = x1 + dx;
      y2 = (-f(x2)+1.0)/2.0; // now x1,x2,y1,y2 in 0.0 to 1.0
      xp1 = (int)(x1*xscale)+xoff;
      yp1 = (int)(y1*yscale)+yoff;
      xp2 = (int)(x2*xscale)+xoff;
      yp2 = (int)(y2*yscale)+yoff;
      g.drawLine(xp1, yp1, xp2, yp2);
    } // end i
  }

  public static void main(String args[])
  {
    new plot_waved();
  }
} // end plot_waved.java