simpledrawboard.java~4~

一个使用Java完成的简易绘图板

package simpledrawboard;

/**
 * 简单的画图板
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 class SimpleDrawBoard extends JFrame implements ActionListener
{
     static int first = 0;
        int x1,y1,x2,y2,px,py,width,hight,flag;
        JRadioButton b1,b2,b3,b4,b5;
        JPanel bottom;
        ButtonGroup group;
        //JFrame n=new JFrame();
        public SimpleDrawBoard()
        {
      super("Example of mouse event handling");

     // Container c=getContentPane();
      setBounds(100,100,450,120);
          setSize(800,600);
      bottom=new JPanel();
      group=new ButtonGroup();
      b1=new JRadioButton("自由绘图");
      b1.addActionListener(this);
      group.add(b1);
      bottom.add(b1);
      b2=new JRadioButton("画直线");
      b2.addActionListener(this);
      group.add(b2);
      bottom.add(b2);
      b3=new JRadioButton("画矩形");
      b3.addActionListener(this);
      group.add(b3);
      bottom.add(b3);
      b4=new JRadioButton("画椭圆");
      b4.addActionListener(this);
      group.add(b4);
      bottom.add(b4);
      b5=new JRadioButton("清空");
      b5.addActionListener(this);
      b5.setVisible(true);
      group.add(b5);
      bottom.add(b5);
      bottom.setVisible(true);
      bottom.repaint();
      add(bottom,BorderLayout.NORTH);

      setVisible(true);
      setDefaultCloseOperation(EXIT_ON_CLOSE);
      setResizable(false);

      addMouseListener(new MouseListener()
      {
        public void mouseClicked(MouseEvent e)
        {
        }
        public void mouseEntered(MouseEvent e)
        {
        }
        public void mouseExited(MouseEvent e)
        {
        }
        public void mousePressed(MouseEvent e)
            {
             if(flag==1||flag==2)
             {
              x1=e.getX();
              y1=e.getY();
              x2=x1;
              y2=y1;
              repaint();
              }
              else if(flag==3||flag==4)
                {
                  x1=e.getX();
                  y1=e.getY();
                  px=x1;py=y1;
                }
           }
           public void mouseReleased(MouseEvent e)
           {
                if(flag==2)
                {
                        x2=x1;
                y2=y1;
                x1=e.getX();
                y1=e.getY();
                repaint();
                }
                else if(flag==3||flag==4)
                {
                   x2=e.getX();
                y2=e.getY();
                if(x1>x2||y1>y2)
                {
                        x1=x1+x2;
                        x2=x1-x2;
                        x1=x1-x2;
                        y1=y1+y2;
                        y2=y1-y2;
                        y1=y1-y2;
                        px=x1;py=y1;
                }
                width=Math.abs(x2-px);
                hight=Math.abs(y2-py);
                repaint();
                }
           }

      });
          addMouseMotionListener(new MouseMotionListener()
      {
        public void mouseDragged(MouseEvent e)
        {
          if(flag==1)
               {
                x2=x1;
                y2=y1;
                x1=e.getX();
                y1=e.getY();
                repaint();
                }

            }
            public void mouseMoved(MouseEvent e)
            {
            }
            });
            }

        public void paint(Graphics g)
        {
            if(first == 0) {
                super.paint(g);
                first = 1;
            }
            g.setColor(Color.white);
            g.drawLine(0,65,800,65);
            g.setColor(Color.black);
            if(flag==1||flag==2)
            g.drawLine(x1,y1,x2,y2);
            else if(flag==3)
            g.drawRect(px,py,width,hight);
            else if(flag==4)
                g.drawOval(px,py,width,hight);
        }

        public void actionPerformed(ActionEvent e)
        {
                try
                {
                    Graphics g=getGraphics();
                        if(e.getSource()==b1)
                                flag=1;
                        else if(e.getSource()==b2)
                                flag=2;
                        else if(e.getSource()==b3)
                                flag=3;
                        else if(e.getSource()==b4)
                          flag=4;
                        else if(e.getSource()==b5)
                         {
                                flag=5;
                                g.clearRect(0,66,800,534);
                         }
                }
                catch(Exception event)
                {
                }
        }
        public static void main(String [] args)
        {
         JFrame m1=new SimpleDrawBoard();
         //m1.show();
        }
}