I use viewport to zoom/pan an image.

Right now, I can pan the image with one finger but I want it with two fingers. How to do it?

The main reason for doing this is to draw with one finger and pan with two fingers.

Here is a part of my image control code..

Code:
        private void Viewport_ManipulationDelta(object sender, ManipulationDeltaEventArgs e)
        {
            if (e.PinchManipulation != null)
            {
                e.Handled = true;

                if (!_pinching)
                {
                    _pinching = true;

                    _relativeCenter = new Point(
                        e.PinchManipulation.Original.Center.X / Image.Width,
                        e.PinchManipulation.Original.Center.Y / Image.Height);
                }

                double w, h;

                if (_width < _height)
                {
                    h = _height * _scale * e.PinchManipulation.CumulativeScale;
                    h = Math.Max(Viewport.ActualHeight, h);
                    h = Math.Min(h, _height);

                    w = h * _width / _height;
                }
                else
                {
                    w = _width * _scale * e.PinchManipulation.CumulativeScale;
                    w = Math.Max(Viewport.ActualWidth, w);
                    w = Math.Min(w, _width);

                    h = w * _height / _width;
                }

                Image.Width = w;
                Image.Height = h;

                Viewport.Bounds = new Rect(0, 0, w, h);

                GeneralTransform transform = Image.TransformToVisual(Viewport);
                Point p = transform.Transform(e.PinchManipulation.Original.Center);

                double x = _relativeCenter.X * w - p.X;
                double y = _relativeCenter.Y * h - p.Y;

                if (w < _width && h < _height)
                {
                    Viewport.SetViewportOrigin(new Point(x, y));
                }
            }
            else if (_pinching)
            {
                e.Handled = true;

                CompletePinching();
            }
        }