//Plot.java
import java.awt.*;
import javax.swing.*;

public class Plot extends JComponent {
  public Plot(Function f, double start, double end,
              double deltaX)
  {
    function = f;
    delta = deltaX;
    from = start;
    to = end;
    findRange(); // find max and min of f(x)
    setSize(200, 100); // default width, height
  }
  public void paint(Graphics g) 
  {
    double x = from;
    double f_of_x = function.valueAt(x);
    while (x < to - delta) {
      double f_of_x_plus_delta;
      f_of_x_plus_delta = function.valueAt(x + delta);
      drawLine(g, x, f_of_x,
               x + delta, f_of_x_plus_delta);
      x = x + delta;
      f_of_x = f_of_x_plus_delta;
    }
    drawLine(g, x, f_of_x, to, function.valueAt(to));
  }
  public void setBounds(int x, int y, 
                        int width, int height)
  {
    xScale = (width - 2) / (to - from);
    yScale = (height - 2) / (fmax - fmin);
    dim = new Dimension(width, height);
    super.setBounds(x, y, width, height);
    repaint();
  }
  public Dimension getMinimumSize() {
    return dim;
  }

  public Dimension getPreferredSize() {
    return getMinimumSize();
  }
  // scale and translate the points from the
  // user's coordinate space to Java's
  private void drawLine(Graphics g,
                         double x1, double y1,
                         double x2, double y2)
  {
    g.drawLine(
                (int)Math.round((x1 - from) * xScale),
                (int)Math.round((fmax - y1) * yScale),
                (int)Math.round((x2 - from) * xScale),
                (int)Math.round((fmax - y2) *yScale));
  }
  // determine the minimum and maximum values of
  // f(x) with x varying between from and to
  private void findRange() {
    fmin = fmax = function.valueAt(from);
    for (double x = from + delta; 
        x < to - delta;
        x = x + delta)
    {
      double f_of_x = function.valueAt(x);
      if (f_of_x < fmin)
        fmin = f_of_x;
      if (f_of_x > fmax)
        fmax = f_of_x;
    }
  }
  private Dimension dim;
  private double fmin, fmax;
  private double xScale, yScale;
  private double from, to, delta;
  private Function function;
}