rollingtest.java

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import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
public class RollingTest extends java.applet.Applet implements Runnable
{
  Thread runThread;
  String s;
  int s_length;// 字符串的长度
  int x_character=0,  // 当前显示到第几个字符串
  y_coord,        // 字符串的Y坐标位置
  textcolor,     // 字符串的颜色值（16进制整数rrggbb）
  backcolor,  // applet背景颜色值（16进制整数rrggbb）
  delay;     //每帧画面的时延（毫秒）
  int appletWidth, appletHeight;
  String font_name; // 字体的名称
  int font_size;    // 字体的尺寸
  Font wordFont;
  FontMetrics wordMetrics;

  public void init()
  {
    String temp;
    appletWidth = size().width;
    appletHeight = size().height;
    temp=getParameter("font");
    font_name= (temp==null) ? "TimesRoman" : temp;
    temp = getParameter("fontsize");
    font_size= (temp==null) ? 12 : Integer.parseInt( temp );
    wordFont = new Font(font_name, Font.PLAIN, font_size);
    if (wordFont == null)
    wordFont = getFont();
    wordMetrics = getFontMetrics (wordFont);
    temp = getParameter("text");
    s=(temp==null) ? "Message goes here...   " : temp;
    s_length=s.length();
    temp = getParameter("textcolor");
    textcolor= (temp==null) ? 0 : Integer.parseInt( temp ,16 );
    temp = getParameter("backcolor");
    backcolor= (temp==null) ? 0xffffff : Integer.parseInt( temp ,16 );
    temp = getParameter("delay");
    delay= (temp==null) ? 100 : Integer.parseInt( temp );
    y_coord=appletHeight/2+(wordMetrics.getHeight()-wordMetrics.getDescent())/2;
  }
  public void start()
  {
    if(runThread==null)
    {
      runThread = new Thread(this);
      runThread.start();
    }
  }
  public void stop()
  {
    if(runThread!=null)
    {
      runThread.stop();
      runThread=null;
    }
  }
  public void run()
  {
    while(true)
    {
      if (x_character++>s_length)
      x_character = 0;
      repaint ();
      try {
        Thread.sleep( delay );
      } catch(InterruptedException e) {}
    }
  }
  public void paint (Graphics g)
  {
    g.setFont (wordFont);
    g.setColor (Color.red);
    g.drawString (s.substring(0,x_character), 8, y_coord);
  }
  public void update(Graphics g)
  {
    if (x_character == 0)
    {
      g.setColor(getBackground());
      g.fillRect(0,0,appletWidth,appletHeight);
      g.setColor(getForeground());
    }
   paint(g);
  }
}