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// The Plotter Applet

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class Plotter extends Applet {
  boolean isStandalone = false;
//Get a parameter value

  public String getParameter(String key, String def) {
    return isStandalone ? System.getProperty(key, def) :
      (getParameter(key) != null ? getParameter(key) : def);
  }
  //Construct the applet

  public Plotter() {
  }
//Initialize the applet
  public void init() {
    try {
    jbInit();
    }
    catch (Exception e) {
    e.printStackTrace();
    }
  }
//Component initialization
  private PlotEngine engine;
  private void jbInit() throws Exception {
    String engname;
    engname=getParameter("engine","PlotEngineImpl");
    Class c=Class.forName(engname);
    engine=(PlotEngine)c.newInstance();
  }
//Get Applet information

  public String getAppletInfo() {
    return "JPlot demo by Al Williams";
  }
  public void paint(Graphics g) {
    int x,y;
    float x0,xscale,yscale;
    xscale=Float.valueOf(getParameter("XScale","1.0")).floatValue();
    yscale=Float.valueOf(getParameter("YScale","1.0")).floatValue();
    x0=Float.valueOf(getParameter("XOff","0.0")).floatValue();
    Dimension d;
    d=this.getSize();
    if (engine==null) return;
    for (x=0;x<d.width;x++) {
      y=d.height-(int)(yscale*engine.f((x+x0)*xscale));
      g.fillRect(x,y,1,1);
    }

  }
}