public class DrawView extends View implements OnTouchListener
{
	private Canvas  	m_Canvas;

	private Path    	m_Path;

	private Paint       m_Paint;

	ArrayList<Pair<Path, Paint>> arrayListPaths = new ArrayList<Pair<Path, Paint>>();

	ArrayList<Pair<Path, Paint>> undonePaths = new ArrayList<Pair<Path, Paint>>();

	private float mX, mY;

	private Bitmap bitmapToCanvas;

	private static final float TOUCH_TOLERANCE = 4;

	public DrawView(Context context)
	{
		super(context);
		setFocusable(true);
		setFocusableInTouchMode(true);
		this.setOnTouchListener(this);

		onCanvasInitialization();
	}

	public void onCanvasInitialization()
	{
		m_Paint = new Paint();
		m_Paint.setAntiAlias(true);
		m_Paint.setDither(true);
		m_Paint.setColor(Color.parseColor("#37A1D1"));
		m_Paint.setStyle(Paint.Style.STROKE);
		m_Paint.setStrokeJoin(Paint.Join.ROUND);
		m_Paint.setStrokeCap(Paint.Cap.ROUND);
		m_Paint.setStrokeWidth(2);

		m_Path = new Path();
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh)
	{
		super.onSizeChanged(w, h, oldw, oldh);

		bitmapToCanvas = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
		m_Canvas = new Canvas(bitmapToCanvas);
	}

	@Override
	protected void onDraw(Canvas canvas)
	{
		canvas.drawBitmap(bitmapToCanvas, 0f, 0f, null);
		for (Pair<Path, Paint> p : arrayListPaths)
		{
		    canvas.drawPath(p.first, p.second);
		}
		canvas.drawPath(m_Path, m_Paint);
	}

	public boolean onTouch(View arg0, MotionEvent event)
	{
		float x = event.getX();
		float y = event.getY();

		switch (event.getAction())
		{
			case MotionEvent.ACTION_DOWN:
			touch_start(x, y);
			invalidate();
			break;
			case MotionEvent.ACTION_MOVE:
			{
				touch_move(x, y);
				invalidate();
				break;
			}
			case MotionEvent.ACTION_UP:
			touch_up();
			invalidate();
			break;
		}
		return true;
	}

	private void touch_start(float x, float y)
	{
		m_Path.reset();
		m_Path.moveTo(x, y);
		mX = x;
		mY = y;
	}

	private void touch_move(float x, float y)
	{
		float dx = Math.abs(x - mX);
		float dy = Math.abs(y - mY);
		if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE)
		{
			m_Path.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
			mX = x;
			mY = y;
		}
	}
	private void touch_up()
	{
		m_Path.lineTo(mX, mY);

		// commit the path to our offscreen
		m_Canvas.drawPath(m_Path, m_Paint);

		// kill this so we don't double draw
		Paint newPaint = new Paint(m_Paint); // Clones the mPaint object
		arrayListPaths.add(new Pair<Path, Paint>(m_Path, newPaint));
		m_Path = new Path();
	}

	public void onClickUndo ()
	{
		if (arrayListPaths.size()>0)
		{
			undonePaths.add(arrayListPaths.remove(arrayListPaths.size()-1));
			invalidate();
		}
		else
		{

		}
	}

	public void onClickRedo ()
	{
		if (undonePaths.size()>0)
		{
			arrayListPaths.add(undonePaths.remove(undonePaths.size()-1));
			invalidate();
		}
		else
		{

		}
	}