// app18_12,拖拽鼠標繪圖
import java.awt.*;  
import java.awt.event.*; 
public class app18_12 extends Frame implements MouseMotionListener,MouseListener
{
   static app18_12 frm=new app18_12();
   int x1,x2,y1,y2; 
   public static void main(String args[])
   {
      frm.setTitle("Free drawing");
      frm.setSize(200,150);  
      frm.addMouseListener(frm);  // 設置MouseListener
      frm.addMouseMotionListener(frm); // 設置MouseMotionListener
      frm.setVisible(true);  
   }
   public void mousePressed(MouseEvent e)
   {
      x1=e.getX();   // 取得鼠標按下時的X坐標 (繪圖起始點是X坐標)
      y1=e.getY();   // 取得鼠標按下時的Y坐標 (繪圖起始點是Y坐標)
   }
   public void mouseDragged(MouseEvent e)
   {
      Graphics g=getGraphics(); 
      x2=e.getX();  // 取得鼠標拖拽時的X坐標
      y2=e.getY();  // 取得鼠標拖拽時的Y坐標
      g.drawLine(x1,y1,x2,y2);  // 繪出(x1,y1)到(x2,y2)的連線
      x1=x2;  // 更新繪圖起始點的X坐標
      y1=y2;  // 更新繪圖起始點的Y坐標 
   } 
   public void mouseMoved(MouseEvent e){} 
   public void mouseReleased(MouseEvent e){} 
   public void mouseEntered(MouseEvent e){} 
   public void mouseExited(MouseEvent e){} 
   public void mouseClicked(MouseEvent e){} 
}