Step 7 : ちらつきの制御

import java.awt.Graphics;
import java.applet.Applet;
import java.awt.Font;
import java.awt.Color;
import java.awt.Event;
import java.awt.FontMetrics;
import java.awt.Image;

public class HelloWorld7 extends Applet implements Runnable{
String input_text;
int xpos=400;
int realLength;
int realHeight;
int width=400;
int height=40;
boolean suspended = false;

Font font= new Font("Helvetica",1,24);
Color color = new Color(0,0,255);
Thread killme=null;
Image im;
Graphics osGraphics;

  public void init(){
  input_text=getParameter("text");
  im=createImage(size().width,size().height);
  osGraphics=im.getGraphics();
  }

  public void paint(Graphics g){
  paintText(osGraphics);
  g.drawImage(im,0,0,null);
  }

  public void paintText(Graphics g){
  g.setColor(Color.black);
  g.fillRect(0,0,width,height);
  g.clipRect(0,0,width,height);
  g.setFont(font);
  g.setColor(color);
  FontMetrics fmetrics=g.getFontMetrics();
  realLength=fmetrics.stringWidth(input_text);
  realHeight=fmetrics.getHeight(); 
  g.drawString(input_text,xpos,(height+realHeight)/2);
  }

public void start(){
if(killme==null){
  killme=new Thread(this);
  killme.start();
  }
}

public void setcoord(){
  xpos =xpos-5;
  if(xpos<-realLength){
  xpos=width;
  }
}

public void run(){
while(killme != null){
 try {Thread.sleep(10);}catch(InterruptedException e){}
 setcoord();
 repaint();
 }
}

public void update(Graphics g){
 paint(g);
 }

public boolean handleEvent(Event evt) {
	if (evt.id == Event.MOUSE_DOWN) {
	    if (suspended) {
	      killme.resume();
	    } else {
	      killme.suspend();
	      }
	    suspended = !suspended;
	    }
	    return true;
      }

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

}