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Java ImageIcons and actioin listeners

I create a simple game where a person clicks on an image, the score is increased by one. It seems simple enough, right? Here's the trick - images will be partially hidden behind other images!

I am currently using several imageIcons to customize my scene. For example, my foreground has the image "foreground.png", my background is "background.png", and my image that is hidden between them is "hiding.png".

My first thought was to simply get the smoothing coordinates of imageIcon, add the heights () and width () to them, and create a mouse listener that will only work in the specified area. However, this will give me a rectangle for the user to click, who will defeat the goal of hiding the object (someone can click on the hard border of the chart behind the foreground).

Do you have any suggestions on how to make the mouse action listener work only with transparent pixels of the Icon image? Yes, I understand that action listeners can only be applied to components (for example, buttons), but the “button” just doesn't do what I want for this project.

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Example 1

Mostly used series JLabelon JLayeredPane. Each label has its own mouse listener, and when you hover over it, it will turn red. But, if there is an inscription above it, it will not respond to mouse events ...

enter image description here

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();
            }
        }
    }
}

Example 2

This example uses a method paintComponentto render images. It checks the pixel alpha of the image at the mouse point to determine if the mouse event should occur or not.

I am a little strict using the alpha value 255, but you can soften it a bit depending on your needs (e.g., about 225) ...

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enter image description here

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;
        }
    }
}
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Source: https://habr.com/ru/post/1538340/

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