Margus Martsepp (Stackoverflow:Wanting a type of grid for a pixel editor)

import java.awt.AWTException;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.MouseInfo;
import java.awt.Point;
import java.awt.Robot;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;
import java.util.Date;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Zoom extends JPanel implements MouseMotionListener {

    private static final int SIZE = 8;
    private static final int S2 = SIZE / 2;
    private static final int SCALE = 48;
    private BufferedImage img;
    private Robot robot;
    private Ticker t;

    private class Ticker extends Thread {
        private long timeRef = new Date().getTime();
        public boolean update = true;
        public JPanel jp = null;
        private int iter = 0;

        public Ticker(JPanel g) {
            super();
            jp = g;
        }

        public void done() {
            update = false;
        }

        public void run() {
            try {
                while (update == true) {
                    BufferedImage img2 = new BufferedImage(SIZE, SIZE,
                            BufferedImage.TYPE_INT_RGB);
                    updateImg(img2);
                    synchronized (img) {
                        img = img2;
                    }
                    paintComponent(jp.getGraphics());
                    StringBuilder sb = new StringBuilder();
                    sb.append(++iter)
                            .append(" frames in ")
                            .append((double) (new Date().getTime() - this.timeRef) / 1000)
                            .append("s.");
                    System.out.println(sb.toString());
                }
            } catch (Exception e) {
                e.printStackTrace();
                update = false;
            }
        }
    }

    private void updateImg(BufferedImage image) {
        Graphics2D gc = null;
        try {
            Point p = MouseInfo.getPointerInfo().getLocation();
            gc = image.createGraphics();
            for (int x = 0; x < 8; x++) {
                for (int y = 0; y < 8; y++) {
                    gc.setColor(robot.getPixelColor(p.x - 4 + x, p.y - 4 + y));
                    gc.drawLine(x, y, x, y);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            gc.dispose();
        }
    }

    public Zoom() {
        super(true);

        this.setPreferredSize(new Dimension(SIZE * SCALE, SIZE * SCALE));

        img = new BufferedImage(SIZE, SIZE, BufferedImage.TYPE_INT_RGB);

        t = new Ticker(this);
        try {
            robot = new Robot();
        } catch (AWTException e) {
            e.printStackTrace(System.err);
        }

    }

    @Override
    protected void paintComponent(Graphics g) {
        try {
            if (img != null)
                synchronized (img) {
                    g.drawImage(img, 0, 0, getWidth(), getHeight(), null);
                }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    @Override
    public void mouseMoved(MouseEvent e) {
        Point p = e.getPoint();
        int x = p.x * SIZE / getWidth();
        int y = p.y * SIZE / getHeight();
        int c = img.getRGB(x, y);
        this.setToolTipText(x + "," + y + ": " + String.format("%08X", c));
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        for (int r = 0; r < SIZE; r++) {
            for (int c = 0; c < SIZE; c++) {
                Color color = robot.getPixelColor(e.getXOnScreen() + c - S2,
                        e.getYOnScreen() + r - S2);
                img.setRGB(c, r, color.getRGB());
            }
        }
        repaint();
    }

    private static void create() {
        JFrame f = new JFrame("Click & drag to zoom.");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Zoom zoom = new Zoom();
        f.add(zoom);
        f.pack();
        f.setVisible(true);
        zoom.addMouseMotionListener(zoom);
        zoom.t.run();
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                create();
            }
        });
    }
}