//The following two lines are needed to open and close a window.
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;

import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;

import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseListener;

public class MouseBug implements PaintListener, MouseListener {

	private Shell shell;
	private Color color;
	private int x, y;

	public MouseBug(Shell s, Color c, int initial_x, int initial_y) {
		shell = s;
		color = c;
		x = initial_x;
		y = initial_y;

		// Add this MouseBug to the lists of the shell's listeners.
		shell.addPaintListener(this);
		shell.addMouseListener(this);

	}

	public String toString() {
		return color + " (" + x + ", " + y + ")";
	}

	public void move(int dx, int dy) {
		x += dx;
		y += dy;

		//A Graphics Context is the brush you paint with.
		paint(new GC(shell));
	}

	private void paint(GC gc) {
		gc.setBackground(color);
		gc.fillRectangle(11 * x, 11 * y, 10, 10); // x, y, width, height
	}

	public void paintControl(PaintEvent event) {
		paint(event.gc);
	}

	public void mouseDown(MouseEvent event) {
		//event.x and event.y are the location in pixels of the event.
		//xclick and yclick are the location in squares of the event.

		final int xclick = event.x / 11;
		final int yclick = event.y / 11;

		final int dx;
		final int dy;

		if (xclick > x) {
			dx = 1;
		} else if (xclick < x) {
			dx = -1;
		} else {
			dx = 0;
		}

		if (yclick > y) {
			dy = 1;
		} else if (yclick < y) {
			dy = -1;
		} else {
			dy = 0;
		}

		move(dx, dy);
	}

	public void mouseUp(MouseEvent event) {
	}

	public void mouseDoubleClick(MouseEvent event) {
	}

	public static void main(String[] args) {

		// The following two lines are needed to open the window.
		final Display display = new Display();
		final Shell shell = new Shell(display);

		Color black = new Color(display, 0, 0, 0); // rgb
		MouseBug b = new MouseBug(shell, black, 1, 1);
		System.out.println(b);

		// Color red = new Color(display, 255, 0, 0);
		// Bug b2 = new Bug(shell, red, 2, 2);

		shell.setText("Volkswagen Bug");
		shell.open();

		// The following six lines are needed to close the window.
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch()) {
				display.sleep();
			}
		}

		black.dispose();
		display.dispose();
	}
}