How do I get the X and Y location of an image in a JScrollPane

Question

I am trying to make a Map Editor for a 2D RPG, and what I currently am trying to do (to place tiles on the ground) is to have a JScrollPane with a JLabel (that has an image

Answer 1

If you use JScrollPane for this, get the value of the vertical scrollbar, and add it to the Y value from the mouse listener and you will have the correct value

Answer 2

Instead of adding the MouseListener to the scrollpane, try adding it to the scroll pane's view component (ie, the thing that the scroll pane is displaying)

The image in this example is 2560x1600

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
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 java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestScrollPanePos {

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

    public TestScrollPanePos() {
        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 JScrollPane(new TestPane()));
                frame.setSize(400, 400);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private BufferedImage bg;
        private Point point;

        public TestPane() {
            try {
                bg = ImageIO.read(new File("/path/to/image));
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            addMouseMotionListener(new MouseAdapter() {

                @Override
                public void mouseMoved(MouseEvent e) {
                    System.out.println(e.getPoint());
                    point = e.getPoint();
                    repaint();
                }

            });
        }

        @Override
        public Dimension getPreferredSize() {
            return bg == null ? new Dimension(200, 200) : new Dimension(bg.getWidth(), bg.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (bg != null) {
                Graphics2D g2d = (Graphics2D) g.create();
                int x = (getWidth() - bg.getWidth()) / 2;
                int y = (getHeight()- bg.getHeight()) / 2;
                g2d.drawImage(bg, x, y, this);
                if (point != null) {
                    FontMetrics fm = g2d.getFontMetrics();
                    g2d.setColor(Color.BLACK);
                    g2d.drawString(point.x + "x" + point.y, point.x, point.y - fm.getHeight() + fm.getAscent());
                }
                g2d.dispose();
            }
        }
    }

}