freedraw1.java

用java 实现一个拖动鼠标来画图的程序由鼠标的移动来决定轨迹。

import java.applet.Applet;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
public class freedraw1 extends Applet implements MouseMotionListener
{
  int x,y;
  public void init()
  {
	  setBackground(Color.cyan);
	  setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
	  addMouseMotionListener(this);
  }
    public void paint(Graphics g)
    {
    	Graphics2D g2d=(Graphics2D)g;
    	g2d.setColor(Color.red);
    	BasicStroke bs1=new BasicStroke(4);//BasicStroke是用来描写GraphicsD图形的外形
    	g2d.setStroke(bs1);
    	Line2D obj1=new Line2D.Double(x,y,x,y);
    	g2d.draw(obj1);
    }
	public void mouseDragged(MouseEvent e) 
	{
	  x=(int)e.getX();
	  y=(int)e.getY();
	  repaint();
	}
    public void update(Graphics g)
    {
    	paint(g);
    }
	public void mouseMoved(MouseEvent arg0) 
	{
      
	}

}