画笔程序说明

//In the last version I have finish the function to write a line ...//This version 0.2 will add more fun things...import java.awt.*;import javax.swing.*;import java.awt.event.*;public class DrawPad extends Frame {IDrawPad idp;JButton b1;JButton b2;JPanel jpl;public void init() {idp=new IDrawPad(this);jpl=new JPanel(new GridLayout(1,2,10,10));b1=new JButton("Black");b2=new JButton("Other");//add(idp);add(idp,BorderLayout.CENTER);add(jpl,BorderLayout.NORTH);jpl.add(b1);jpl.add(b2);b1.addActionListener(idp);idp.init();idp.setBackground(Color.magenta);this.setBackground(Color.white);this.setVisible(true);addWindowListener(new WindowAdapter(){@Overridepublic void windowClosing(WindowEvent e) {System.exit(0);}});}public static void main(String args[]) {new DrawPad().init();}}class IDrawPad extends JPanel implements ActionListener{DrawPad dp;IDrawPad(DrawPad dp) {this.dp=dp;}Color c=new Color(0, 150, 150);Point Frond=new Point(0,0);Point Back=new Point(0,0);Image tem;int i=1;boolean s_s;@SuppressWarnings("deprecation")public void actionPerformed(ActionEvent e) {if(i%4==3) {dp.b1.setLabel("CYAN");c=Color.cyan;dp.b1.setBackground(c);i++;//System.out.println(i);}else if(i%4==2){dp.b1.setLabel("Black");c=Color.black;dp.b1.setBackground(c);i++;//System.out.println(i);}else if(i%4==1) {dp.b1.setLabel("RED");c=Color.red;dp.b1.setBackground(c);i++;//System.out.println(i);}else if(i%4==0) {dp.b1.setLabel("BLUE");c=Color.blue;dp.b1.setBackground(c);i++;//System.out.println(i);}}public void init() {setBounds(100,100,700,550);setBackground(Color.orange);setVisible(true);this.addMouseMotionListener(new MouseE());this.addMouseListener(new MouseE());}public void update(Graphics g) {if(tem==null) {tem=this.createImage(700, 550);}Graphics tg=tem.getGraphics();paint(tg);g.drawImage(tem, 0, 0, null);}public void paint(Graphics g) {g.setColor(c);g.drawLine(Back.x, Back.y, Frond.x, Frond.y);Back=Frond;}}class MouseE extends MouseMotionAdapter implements MouseListener {IDrawPad y;@Overridepublic void mouseClicked(MouseEvent e) {// TODO Auto-generated method stub}@Overridepublic void mousePressed(MouseEvent e) {y=(IDrawPad)e.getSource();//System.out.println(y.Back);y.Back=e.getPoint();}@Overridepublic void mouseReleased(MouseEvent e) {// TODO Auto-generated method stub}@Overridepublic void mouseEntered(MouseEvent e) {// TODO Auto-generated method stub}@Overridepublic void mouseExited(MouseEvent e) {// TODO Auto-generated method stub}public void mouseDragged(MouseEvent e) {y=(IDrawPad)e.getSource();y.Frond=e.getPoint();y.repaint();}}

1.在最初,我直接在DrawPad上面作画,然后不断的update()这个画面....这样这个画面其实都是一个画板.但是实际中,我们只需要在一个画板区域作画...其他地方放置一个按键等功能...

2.所以我们需要在主窗口中添加一个可以画画的组件.也就是拥有paint()方法的一个组件...我们发现JPanel中有这个方法....所以我们新建一个IDrawPad从JPanel中继承...