import java.awt.*;

public class Gas extends java.applet.Applet{


  public DrawGas  drawing;
  public GasSimulation simulation;
  public Controls usercontrols;
  public Thread runner;
  public Image   offscreenImage;
  public Graphics offscreenGraphics;

  public int N=25,diameter,iborder,jborder,stepsize;
  
  public void init(){
    diameter=30;
    iborder=450;
    jborder=450;
    stepsize=10;


    setLayout(new BorderLayout());       //what does this do?
    usercontrols = new Controls(this);
    drawing = new DrawGas(this);

    add("Center",drawing);
    add("South",usercontrols);
    offscreenImage=createImage(this.size().width,this.size().height);
    offscreenGraphics=offscreenImage.getGraphics();    

  }

  public void start(){
    if (simulation == null) {
      simulation = new GasSimulation(this);
      runner=new Thread(simulation);
      runner.start();
    } else {
      runner.resume();
    }
  }

  public void stop(){
    if(runner!=null){
      runner.suspend();
    }
  }

}