Java ImageIcons 和 Action 监听器

Question

我正在创建一个简单的游戏，在这个游戏中，一个人点击一张图片，得分会增加一分。 这看起来很简单，对吧？关键是——图片将部分隐藏在其他图片后面!

目前，我正在使用多个 imageIcons 来设置我的场景。例如，我的前景有一个图像“foreground.png”，我的背景是“background.png”，我隐藏在两者之间的图像是“hiding.png”。

我的第一个想法是简单地获取 imageIcon 隐藏的坐标，将 height() 和 width() 添加到它们，并创建一个只在该指定区域工作的鼠标监听器。但是，这会给我一个供用户单击的矩形，这会破坏隐藏对象的目的(有人可以单击前景后面图形的刚性边界)。

对于如何使鼠标 Action 监听器仅在 imageIcon 的可见像素上工作，您有什么建议吗？是的，我知道 Action 监听器只能应用于组件(例如按钮) 但是“按钮”并不能满足我对这个项目的要求。

Answer 1

示例 1

这基本上是在 JLayeredPane 上使用了一系列 JLabel。每个标签都有自己的鼠标监听器，当您将鼠标悬停在它上面时，它会变成红色。但是，如果上面有标签，它不会响应鼠标事件...

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class ClickMyImages {

    public static void main(String[] args) {
        new ClickMyImages();
    }

    public ClickMyImages() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JLayeredPane {

        public TestPane() {
            try {
                BufferedImage img1 = ImageIO.read("/Image1");
                BufferedImage img2 = ImageIO.read("/Image2");
                BufferedImage img3 = ImageIO.read("/Image3");
                BufferedImage img4 = ImageIO.read("/Image4");
                BufferedImage img5 = ImageIO.read("/Image5");

                JLabel label1 = new ClickableLabel(new ImageIcon(img1));
                JLabel label2 = new ClickableLabel(new ImageIcon(img2));
                JLabel label3 = new ClickableLabel(new ImageIcon(img3));
                JLabel label4 = new ClickableLabel(new ImageIcon(img4));
                JLabel label5 = new ClickableLabel(new ImageIcon(img5));

                Dimension masterSize = getPreferredSize();

                Dimension size = label1.getPreferredSize();
                label1.setBounds((masterSize.width - size.width) / 2, (masterSize.height - size.height) / 2, size.width, size.height);
                Point masterPoint = label1.getLocation();
                size = label2.getPreferredSize();
                label2.setBounds(
                        masterPoint.x - (size.width / 2), 
                        masterPoint.y - (size.height  / 2), 
                        size.width, size.height);
                size = label3.getPreferredSize();
                label3.setBounds(
                        masterPoint.x + (size.width / 2), 
                        masterPoint.y - (size.height  / 2), 
                        size.width, size.height);
                size = label4.getPreferredSize();
                label4.setBounds(
                        masterPoint.x - (size.width / 2), 
                        masterPoint.y + (size.height  / 2), 
                        size.width, size.height);
                size = label5.getPreferredSize();
                label5.setBounds(
                        masterPoint.x + (size.width / 2), 
                        masterPoint.y + (size.height  / 2), 
                        size.width, size.height);

                add(label1);
                add(label2);
                add(label3);
                add(label4);
                add(label5);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(800, 800);
        }
    }

    // This is for demonstration purposes only!
    public class ClickableLabel extends JLabel {

        private boolean isIn = false;

        public ClickableLabel(Icon image) {
            super(image);
            addMouseListener(new MouseAdapter() {
                @Override
                public void mouseEntered(MouseEvent e) {
                    isIn = true;
                    repaint();
                }

                @Override
                public void mouseExited(MouseEvent e) {
                    isIn = false;
                    repaint();
                }
            });
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (isIn) {
                Graphics2D g2d = (Graphics2D) g.create();
                g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
                g2d.setColor(Color.RED);
                g2d.fillRect(0, 0, getWidth(), getHeight());
                g2d.dispose();
            }
        }
    }
}

示例 2

此示例使用 paintComponent 方法来渲染图像。它检查鼠标点处图像的像素 alpha，以确定鼠标事件是否应该落空。

我使用 255 的 alpha 值有点严格，但您可以根据您的需要稍微软化它(例如 225 之类的东西)...

我已经对图层进行了硬编码，以便树始终位于松鼠上方，但是按照您希望它们出现的顺序将所有图像添加到 List 并不难简单地沿着列表向下运行，直到你被击中。

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Composite;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class ClickMyDrawnImages {

    public static void main(String[] args) {
        new ClickMyDrawnImages();
    }

    public ClickMyDrawnImages() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private BufferedImage tree;
        private BufferedImage squirrel;
        private BufferedImage mouseOver;

        public TestPane() {
            try {
                tree = ImageIO.read(new File("Tree.png"));
                squirrel = ImageIO.read(new File("Squirrel.png"));
            } catch (IOException exp) {
                exp.printStackTrace();
            }
            addMouseMotionListener(new MouseAdapter() {
                @Override
                public void mouseMoved(MouseEvent e) {
                    if (withinTree(e.getPoint())) {
                        mouseOver = tree;
                    } else if (withinSquirrel(e.getPoint())) {
                        mouseOver = squirrel;
                    } else {
                        mouseOver = null;
                    }
                    repaint();
                }
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        protected boolean withinTree(Point p) {
            return withinBounds(p, getTreeBounds(), tree);
        }

        protected boolean withinSquirrel(Point p) {
            return !withinBounds(p, getTreeBounds(), tree) && withinBounds(p, getSquirrelBounds(), squirrel);
        }

        protected Rectangle getTreeBounds() {
            int width = getWidth();
            int height = getHeight();

            int x = (width - tree.getWidth()) / 2;
            int y = (height - tree.getHeight()) / 2;

            return new Rectangle(x, y, tree.getWidth(), tree.getHeight());
        }

        protected Rectangle getSquirrelBounds() {
            Rectangle bounds = getTreeBounds();

            return new Rectangle(
                    bounds.x - (squirrel.getWidth() / 4),
                    (getHeight() - squirrel.getHeight()) / 2,
                    squirrel.getWidth(), squirrel.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            int width = getWidth();
            int height = getHeight();

            int x = (width - tree.getWidth()) / 2;
            int y = (height - tree.getHeight()) / 2;

            g.drawImage(highlight(squirrel), x - (squirrel.getWidth() / 4), (height - squirrel.getHeight()) / 2, this);
            g2d.drawImage(highlight(tree), x, y, this);

            g2d.dispose();
        }

        protected BufferedImage highlight(BufferedImage img) {
            BufferedImage highlight = img;
            if (img.equals(mouseOver)) {
                highlight = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_INT_ARGB);
                Graphics2D g2d = highlight.createGraphics();
                g2d.setColor(Color.RED);
                g2d.drawImage(img, 0, 0, this);

                g2d.setComposite(AlphaComposite.SrcAtop.derive(0.5f));
                g2d.fillRect(0, 0, highlight.getWidth(), highlight.getHeight());
                g2d.dispose();
            }
            return highlight;
        }

        protected boolean withinBounds(Point p, Rectangle bounds, BufferedImage image) {
            boolean withinBounds = false;
            if (bounds.contains(p)) {
                int x = p.x - bounds.x;
                int y = p.y - bounds.y;
                int pixel = image.getRGB(x, y);
                int a = (pixel >> 24) & 0xFF;
                // could use a little weighting, so translucent pixels can be effected
                if (a == 255) {
                    withinBounds = true;
                }
            }
            return withinBounds;
        }
    }
}