我如何创建一个包含两个图像的JPanel，而鼠标悬停在其中却只显示下面一个图像的一部分？

Question

我正在尝试创建一个按钮面板，使单击的按钮变成“不同颜色”。即显示背景图像。ps我只需要这种方法（带有2张图像），不需要其他任何东西。谢谢 ！

例如：

public class TestPane extends JPanel {

        private BufferedImage   imgUnclicked;
        private BufferedImage   imgClicked;
        private Point           mousePoint;

        public TestPane() {
            try {
                imgUnclicked = ImageIO.read(new File("C:\\Users\\Me\\Desktop\\tmp\\Uncolored.png"));
                imgClicked = ImageIO.read(new File("C:\\Users\\Me\\Desktop\\tmp\\Colored.png"));
            } catch (IOException ex) {
                Logger.getLogger(Spotlight.class.getName()).log(Level.SEVERE, null, ex);
            }

            addMouseMotionListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    mousePoint = e.getPoint();
                    repaint();
                }
            });
        }
    }
    @Override
    protected void paintComponent(Graphics g) {
        //Draw imgClicked
        //Draw imgUnclicked with some rectangular area around mouse click subtracted
    }
}

Answer 1

无需重新发明轮子。而是使用JToggleButton（适当配置）。一个按钮将同时响应鼠标 和 键盘输入。

import java.awt.*;
import java.net.*;
import javax.imageio.ImageIO;
import javax.swing.*;

class ChangeImageOnClick {

    public static void main(String[] args) throws Exception {
        URL url1 = new URL("http://i.stack.imgur.com/gJmeJ.png");
        final Image img1 = ImageIO.read(url1);
        URL url2 = new URL("http://i.stack.imgur.com/wCF8S.png");
        final Image img2 = ImageIO.read(url2);
        Runnable r = new Runnable() {

            @Override
            public void run() {
                JToggleButton btn = new JToggleButton("Click me!");
                btn.setIcon(new ImageIcon(img1));
                btn.setSelectedIcon(new ImageIcon(img2));

                btn.setContentAreaFilled(false);
                btn.setBorderPainted(false);

                JOptionPane.showMessageDialog(null, btn);
            }
        };
        SwingUtilities.invokeLater(r);
    }
}