Hi I found a class ReadingPixels someone wrote on the net which given an image it dispays the x,y,r,g,b values as the mouse is over the image. I have a separate class I want to add the panel to. I can add the panel to my frame however I think the problem is that the image is not being passed to the ReadingPixels class.


import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.swing.*;

public class ReadingPixels extends JPanel {
    BufferedImage image;
    JLabel[] labels;

    public ReadingPixels(BufferedImage image) {
        this.image = image;

    protected void paintComponent(Graphics g) {
        int x = (getWidth() - image.getWidth())/2;
        int y = (getHeight() - image.getHeight())/2;
        g.drawImage(image, x, y, this);

    public Dimension getPreferredSize() {
        return new Dimension(image.getWidth(), image.getHeight());

    private void showPixel(Point p) {
        int w = getWidth();
        int h = getHeight();
        int iw = image.getWidth();
        int ih = image.getHeight();
        Rectangle rect = new Rectangle(iw, ih);
        rect.x = (w - iw)/2;
        rect.y = (h - ih)/2;
        int x = 0, y = 0, a = 0, r = 0, g = 0, b = 0;
        if(rect.contains(p)) {
            x = p.x - rect.x;
            y = p.y - rect.y;
            int pixel = image.getRGB(x, y);
            a = (pixel >> 24) & 0xff;
            r = (pixel >> 16) & 0xff;
            g = (pixel >>  8) & 0xff;
            b = (pixel >>  0) & 0xff;
        setLabels(x, y, a, r, g, b);

    private void setLabels(int x, int y, int a, int r, int g, int b) {

    private JPanel getLabels() {
        labels = new JLabel[6];
        for(int i = 0; i < labels.length; i++) {
            labels[i] = new JLabel();
        Dimension d = new Dimension(35, 25);
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(2,2,2,2);
        addComponents("x =", labels[0], panel, gbc, d, 1.0, 0  );
        addComponents("y =", labels[1], panel, gbc, d, 0,   1.0);
        addComponents("a =", labels[2], panel, gbc, d, 1.0, 0  );
        addComponents("r =", labels[3], panel, gbc, d, 0,   0  );
        addComponents("g =", labels[4], panel, gbc, d, 0,   0  );
        addComponents("b =", labels[5], panel, gbc, d, 0,   1.0);
        return panel;

    private void addComponents(String s, JComponent jc, Container c,
                               GridBagConstraints gbc, Dimension d,
                               double weightx1, double weightx2) {
        gbc.weightx = weightx1;
        gbc.anchor = GridBagConstraints.EAST;
        c.add(new JLabel(s), gbc);
        gbc.weightx = weightx2;
        gbc.anchor = GridBagConstraints.WEST;
        c.add(jc, gbc);

    public static void main(String[] args) throws IOException {
        File file = new File("images/blackBear.jpg");
        BufferedImage image = javax.imageio.ImageIO.read(file);
        ReadingPixels test = new ReadingPixels(image);
        JFrame f = new JFrame("ReadingPixels");
        f.add(new JScrollPane(test));
        f.add(test.getLabels(), "Last");

    private MouseMotionListener mml = new MouseMotionAdapter() {
        public void mouseMoved(MouseEvent e) {
            Point p = e.getPoint();

How my class RunProgram works is that the user selects an image to open. So what I want is when the image is open I want the ReadPixels class to display the pixel information of that image that is loaded.

This is the code in my class that opens a picture on a panel

/** Method which takes an image file and opens it on a panel
     * @param f file to be opened
     * @return fileR
    public File openFileR(File f) {
        try {
            tmpImageR = ImageIO.read(f);
            Image toGray = (Image) tmpImageR;
            largeImageR = new ImageIcon(toGray);
            rightPic = new JLabel(largeImageR);
            rightPic.setBorder(new OvalBorder());
        } catch (IOException ex) {
        rightPic.setPreferredSize(new Dimension(350, 350));
        return fileR;

I'm not too sure how to connect this to my class. Can anyone help?
Thank you

Look at the main(...) method in the ReadingPixels class. It is an example of how to call/use the class.

I have a class which implements a JPanel and when an image is loaded, it is loaded to that panel. Because this too is a panel I tried merging it will my image panel class however it doesn't work. I wanted a way for the lables to be added to the bottom of my panel. I tried doing this:

public File openFileL(File f) {
        try {
            tmpImageL = ImageIO.read(f);
            tmpImageL = createGrayscalePic(tmpImageL);
//            runGrabPixels(tmpImage);
            Image toGray = (Image) tmpImageL;
            largeImageL = new ImageIcon(toGray);
            leftPic = new JLabel(largeImageL);
            leftPic.setBorder(new OvalBorder());
        } catch (IOException ex) {
        leftPic.setPreferredSize(new Dimension(350, 350));
        PicturePanel p = new PicturePanel(tmpImageL);
        return fileL;

I have run the code again and the labels are added to the bottom of my screen but however only the values are shown when i scroll over those lables. It seems that the picture is not on the same panel therefore when I scroll over it nothing happens. How could I rectify this?

Thank you

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