painter.java

Java语言

// Using class MouseMotionAdapter.
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;

public class Painter extends JFrame {
   private int xValue = -10, yValue = -10;

   public Painter()
   {
      super( "A simple paint program" );

      getContentPane().add(
         new Label( "Drag the mouse to draw" ),
         BorderLayout.SOUTH );

      addMouseMotionListener(
         new MouseMotionAdapter() {
            public void mouseDragged( MouseEvent e )
            {
               xValue = e.getX();
               yValue = e.getY();
               repaint();
            }           
         }
      );

      setSize( 300, 150 );  
      show();   
   }

   public void paint( Graphics g )
   {
      g.fillOval( xValue, yValue, 4, 4 );
   }

   public static void main( String args[] )
   {
      Painter app = new Painter();

      app.addWindowListener(
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
            {
               System.exit( 0 );
            }
         }
      );
   }
}