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

//The following two lines are needed to respond to an uncovering.
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;

//The following two lines are needed to respond to a keystroke.
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;

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

public class Bug implements PaintListener, KeyListener {

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

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

		//Add this bug to the list of the shell's PaintListeners
		//and to the list of the shell's KeyListeners.

		shell.addPaintListener(this);
		shell.addKeyListener(this);
	}

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

	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
	}

	//This method is called whenever the Bug is exposed.

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

	//This method is called whenever a key is pressed.

	public void keyPressed(KeyEvent event) {
		final char c = event.character;

		if (c == 'h') {
			move(-1, 0); // left
		} else if (c == 'j') {
			move(0, 1); // down
		} else if (c == 'k') {
			move(0, -1); // up
		} else if (c == 'l') {
			move(1, 0); // right
		}
		// Ignore any other keystroke.
	}

	public void keyReleased(KeyEvent 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
		Bug b = new Bug(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();
	}
}