Swing 实现简单的自定义不规则按钮组件

学习java swing，参考WilliamChen blog中关于Component的介绍，并使用Java2d 中的Paint类，自己实现了一个简单的五角星形状的自定义按钮，颜色实现渐变的效果。
特点：
五角星形状按钮
颜色渐变
相关技术：
如何自定义简单组件
如何使用Graphics2D的Paint类实现颜色渐变效果

运行界面如下：



组件代码如下：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
/**
*一个标准的五角星按钮，中间为空，通过五个点连接而成。
*颜色从上到下渐变，由topColor和bottomColor控制
*
* @author sunsnowad
* @date 2009-7-27
*/
//TODO to be continued
public class JRegularStarButton extends JComponent{
private boolean isPressed;
private ArrayList<ActionListener> listeners =
new ArrayList<ActionListener>();
private Polygon region;//按钮实际区域
private JRegularStarButton thisButton;//标识当前对象

private int gapTopOrLeft = 1;//最上点或最左点距边界的像素值
private int gapBottomOrRight = 1;//最下点或最右点距边界的像素值
private Color topColor = Color.yellow;//颜色渐变1
private Color bottomColor = Color.red;//颜色渐变2

public JRegularStarButton(){
isPressed = false;
region = new Polygon();
thisButton = this;
this.addMouseListener(new CustomMouseListener());
}

public void addActionListener(ActionListener listener){
listeners.add(listener);
}

public void removeActionListener(ActionListener listener){
listeners.remove(listener);
}

protected void fireActionPerformed(ActionEvent event){
for(ActionListener listener:listeners){
listener.actionPerformed(event);
}
}
/**
*
* @return StarButton的star区域
*/
public Polygon getRegion(){
return region;
}

@Override
public void paint(Graphics g){
super.paint(g);

Graphics2D g2 = (Graphics2D)g;

//打开反锯齿开关antialiasing
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);

//GradientPaint渐变颜色控制
GradientPaint paint;

if(isPressed){
paint = new GradientPaint(
getWidth()/2,0,topColor,getWidth()/2,getHeight(),bottomColor);
g2.setPaint(paint);
g2.fillPolygon(region);
}
else{
paint = new GradientPaint(
getWidth()/2,0,bottomColor,getWidth()/2,getHeight(),topColor);
g2.setPaint(paint);
g2.fillPolygon(region);
}
}

@Override
public void setBounds(int x, int y, int width, int height){
region = new Polygon();
Point[] pointSet = calcStarRegion(width,height);
if(pointSet == null)
return;
for(Point p : pointSet){
region.addPoint(p.x, p.y);
}
super.setBounds(x, y, width, height);
}

/**
* 设置按钮按下状态
* @param isPressed
*/
public void setPressed(boolean isPressed){
this.isPressed = isPressed;
if(isShowing())
repaint();
}
/**
*
* @return 返回按钮的按下状态
*/
public boolean isPressed(){
return isPressed;
}

/**
* @return the topColor
*/
public Color getTopColor() {
return topColor;
}

/**
* @param topColor the topColor to set
*/
public void setTopColor(Color topColor) {
this.topColor = topColor;
if(isShowing())
repaint();
}

/**
* @return the bottomColor
*/
public Color getBottomColor() {
return bottomColor;
}

/**
* @param bottomColor the bottomColor to set
*/
public void setBottomColor(Color bottomColor) {
this.bottomColor = bottomColor;
if(isShowing())
repaint();
}

/**
*
* @param x
* @param y
* @param width
* @param height
* @return star区域的点集
*/
private Point[] calcStarRegion(int width, int height){
int minSizeOfButton = gapTopOrLeft+gapBottomOrRight;
if(height < minSizeOfButton || width < minSizeOfButton){
return null;//如果太小的按钮则不显示，太小抛出异常
}
Point[] result = new Point[5];
double sin36 = Math.sin(Math.PI/5);
double cos36 = Math.cos(Math.PI/5);
double sin72 = Math.sin(Math.PI*2/5);
double cos72 = Math.cos(Math.PI*2/5);

double radius;

if(width > height){
double heightOfStar = height - minSizeOfButton;
radius = heightOfStar/(1+cos36);

result[0] = new Point((int)(width/2.0), gapTopOrLeft);

result[1] = new Point(
(int)((int)(width/2.0) + radius*sin36),
height-gapBottomOrRight);

result[2] = new Point(
(int)((int)(width/2.0) - radius*sin72),
(int)((int)(height/2.0) - radius*cos72));

result[3] = new Point(
(int)((int)(width/2.0) + radius*sin72),
(int)((int)(height/2.0) - radius*cos72));

result[4] = new Point(
(int)((int)(width/2.0) - radius*sin36),
height-gapBottomOrRight);
}
else{
double widthOfStar = width - minSizeOfButton;
radius = widthOfStar/(1+cos36);

result[0] = new Point(
(int)(width/2.0),
(int)((int)(height/2.0)-radius));

result[1] = new Point(
(int)((int)(width/2.0) + radius*sin36),
(int)((int)(height/2.0) + radius*cos36));

result[2] = new Point(
(int)((int)(width/2.0) - radius*sin72),
(int)((int)(height/2.0) - radius*cos72));

result[3] = new Point(
(int)((int)(width/2.0) + radius*sin72),
(int)((int)(height/2.0) - radius*cos72));

result[4] = new Point(
(int)((int)(width/2.0) - radius*sin36),
(int)((int)(height/2.0) + radius*cos36));
}
return result;
}
/**
*
* @author sunsnowad
* 处理鼠标按下，当按下时出发所有注册的actionListener
*/
class CustomMouseListener extends MouseAdapter{

@Override
public void mousePressed(MouseEvent e){
Point p = e.getPoint();
if(e.getButton() == MouseEvent.BUTTON1 && getRegion().contains(p)){
isPressed = true;
repaint();
fireActionPerformed(new ActionEvent(thisButton, 0, null));
}
}
@Override
public void mouseReleased(MouseEvent e){
if(e.getButton() == MouseEvent.BUTTON1){
isPressed = false;
repaint();
}
}
}
}