SuperMap.WindowsPhone.Mapping.Map.OnManipulationDelta C# (CSharp) Method

        protected override void OnManipulationDelta(ManipulationDeltaEventArgs e)
        {
            base.OnManipulationDelta(e);

            //if (this.Action != null)
            //{
            //    this.Action.OnManipulationDelta(e);
            //}
            Point scale = new Point(Math.Abs(e.DeltaManipulation.Scale.X), Math.Abs(e.DeltaManipulation.Scale.Y));
            _center = e.ManipulationContainer.TransformToVisual(this).Transform(e.ManipulationOrigin);

            _centerP = ScreenToMap(_center);
            if (IsPinchOrStretch(scale))
            {
                double num = (scale.X + scale.Y) / 2;
                oldResolution = this.mapResolution;
                double newResolution = this.mapResolution / num;
                newResolution = MathUtil.MinMaxCheck(newResolution, MinResolution, MaxResolution);
                num = this.mapResolution / newResolution;
                double num1 = _center.X - currentSize.Width / 2;
                double num2 = _center.Y - currentSize.Height / 2;
                ZoomToResolution(newResolution, new Point2D(_centerP.X - newResolution * num1, _centerP.Y + newResolution * num2), true);

            }
            else
            {
                this.PanHelper.DeltaPan(Convert.ToInt32(e.DeltaManipulation.Translation.X), Convert.ToInt32(e.DeltaManipulation.Translation.Y), this.PanDuration, true);
            }
        }