ColourPicker.java

/**
 * @author Steven Sams
 * RGB Colour inspector desktop tool
 */

import java.awt.AWTException;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.MouseInfo;
import java.awt.Color;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.image.BufferedImage;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.SwingConstants;

public class ColourPicker {

    private ColourPicker() {

        Color colour;

        JPanel panel = new JPanel();
        panel.setBorder(BorderFactory.createLineBorder(Color.BLACK, 1));
        panel.setLayout(new BorderLayout());

        JLabel label = new JLabel();
        label.setHorizontalTextPosition(SwingConstants.CENTER);

        JWindow frame = new JWindow();
        frame.setLayout(new BorderLayout());
        frame.setPreferredSize(new Dimension(128, 128));
        frame.setAlwaysOnTop(true);
        frame.add(panel, BorderLayout.CENTER);
        frame.add(label, BorderLayout.SOUTH);
        frame.pack();
        frame.setVisible(true);

        try {
            Robot robot = new Robot();
            while (true) {
                colour = robot.getPixelColor(MouseInfo.getPointerInfo().getLocation().x, MouseInfo.getPointerInfo().getLocation().y);
                frame.setLocation(MouseInfo.getPointerInfo().getLocation().x + 10, MouseInfo.getPointerInfo().getLocation().y - 10);
                BufferedImage image=robot.createScreenCapture(new Rectangle(MouseInfo.getPointerInfo().getLocation(), new Dimension(10,10)));
                panel.removeAll();
                panel.add(new JLabel(new ImageIcon(image.getScaledInstance(panel.getWidth(), panel.getHeight(), BufferedImage.SCALE_FAST))), BorderLayout.CENTER);
                label.setText(colour.getRed() + ", " + colour.getGreen() + ", " + colour.getBlue());
                panel.validate();
                Thread.sleep(10);
            }
        } catch (InterruptedException ex) {
            Logger.getLogger(ColourPicker.class.getName()).log(Level.SEVERE, null, ex);
        } catch (AWTException ex) {
            Logger.getLogger(ColourPicker.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static void main(String args[]) {
        ColourPicker picker = new ColourPicker();
    }
}