import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

//圖片的拖動效果

public class DragPictureDemo extends JFrame {

   JLabel jlPic; //圖片，用于拖動

   public DragPictureDemo() {
   	super("圖片的拖動效果");  //調用父類構造函數
   	Icon image=new ImageIcon(this.getClass().getResource("1.jpg"));  //實例化圖標
		jlPic = new JLabel(image);  //實例化帶圖片的標簽
      getContentPane().add(jlPic);  //增加標簽到容器上
      
      DragPicListener listener=new DragPicListener();  //鼠標事件處理
      jlPic.addMouseListener(listener);  //增加標簽的事件處理
      jlPic.addMouseMotionListener(listener);       
      
      setSize(300,200);  //設置窗口尺寸
      setVisible(true);  //設置窗口為可視
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  //關閉窗口時退出程序
   }
   
   class DragPicListener implements MouseInputListener{  //鼠標事件處理
      Point p=new Point(0,0); //坐標點
   	public void mouseMoved(MouseEvent e){}
   	public void mouseDragged(MouseEvent e){
       	Point newP=SwingUtilities.convertPoint(jlPic,e.getPoint(),jlPic.getParent()); //轉換坐標系統
       	jlPic.setLocation(jlPic.getX()+(newP.x-p.x),jlPic.getY()+(newP.y-p.y)); //設置標簽的新位置
      	p=newP; //更改坐標點
   	}
   	public void mouseReleased(MouseEvent e){}
   	public void mouseEntered(MouseEvent e){}
   	public void mouseExited(MouseEvent e){}
   	public void mouseClicked(MouseEvent e){}
   	public void mousePressed(MouseEvent e){
       	p=SwingUtilities.convertPoint(jlPic,e.getPoint(),jlPic.getParent()); //得到當前坐標點
   	}   
   }

    public static void main(String[] args) {
		new DragPictureDemo();
   } 
}