// FFTGraph.java
import java.awt.*;

public class FFTGraph extends Canvas
{
   private int[] xi, yi, yffti;
   private double[] x, y, yfft;
   private double xMin, xMax, yMin, yMax;
   private int width, height;
   private boolean overlay, showFFT, showNormal;

   public FFTGraph()
   {
      setBackground(Color.black);
   }

   public Dimension getPreferredSize()
   {
      return new Dimension(350, 250);
   }

   private void findMinAndMax()
   {
      yMin = yMax = y[0];
      xMin = x[0];
      xMax = x[x.length - 1];
      for(int i = 0; i < y.length; i++)
      {
         if (y[i] < yMin)
            yMin = y[i];
         if (yfft[i] < yMin)
            yMin = yfft[i];
         if (y[i] > yMax)
            yMax = y[i];
         if (yfft[i] > yMax)
            yMax = yfft[i];
      }
      yMin = yMin - 0.1 * Math.abs(yMin);
      yMax = yMax + 0.1 * Math.abs(yMax);
   }

   public void plot(double _x[], double _y[], double _yfft[], boolean _overlay,
                    boolean _showFFT, boolean _showNormal)
   {
      x = _x;
      y = _y;
      yfft = _yfft;
      overlay = _overlay;
      showFFT = _showFFT;
      showNormal = _showNormal;
      xi = new int[x.length];
      yi = new int[y.length];
      yffti = new int[yfft.length];
      findMinAndMax();
      fitToScreen();
   }

   public void fitToScreen()
   {
      if (x != null)
      {
         width = this.getSize().width;
         height = this.getSize().height;
         for(int i = 0; i < y.length; i++)
         {
            xi[i] = changeXCoords(x[i]);
            if (!overlay)
            {
               yi[i] = (changeYCoords(y[i]) + height) / 2;
               yffti[i] = changeYCoords(yfft[i]) / 2;
            }
            else
            {
               yi[i] = changeYCoords(y[i]);
               yffti[i] = changeYCoords(yfft[i]);
            }
         }
         repaint();
      }
   }

   private int changeXCoords(double x)
   {
      return (int)Math.round(((double)width / (xMax - xMin)) *
                             (x - xMax) + (double)width - 1);
   }

   private int changeYCoords(double y)
   {
      return (int)Math.round(((double)height / (yMin - yMax)) *
                             (y - yMin) + (double)height - 1);
   }

   public void paint(Graphics g)
   {
      g.setColor(Color.black);
      g.fillRect(0, 0, this.getSize().width, this.getSize().height);
      g.setColor(Color.darkGray);
      for(int i = 0; i < 8; i++)
         g.drawLine((i * width) / 8, 0, (i * width) / 8, height);
      if (xi != null)
      {
         if ((width != this.getSize().width) ||
             (height != this.getSize().height))
            fitToScreen();
         if (!overlay)
         {
            g.setColor(Color.darkGray);
            g.drawLine(0, height / 2, width, height / 2);
         }
         if (showNormal)
         {
            g.setColor(Color.white);
            g.drawPolyline(xi, yi, xi.length);
         }
         if (showFFT)
         {
            g.setColor(Color.green);
            g.drawPolyline(xi, yffti, xi.length);
         }
      }
   }

}