public class DPIUtils
    {
        private static double _dpiX = 1.0;
        private static double _dpiY = 1.0;
        public static double DPIX
        {
            get
            {
                return DPIUtils._dpiX;
            }
        }
        public static double DPIY
        {
            get
            {
                return DPIUtils._dpiY;
            }
        }
        public static void Init(System.Windows.Media.Visual visual)
        {
            Matrix transformToDevice = System.Windows.PresentationSource.FromVisual(visual).CompositionTarget.TransformToDevice;
            DPIUtils._dpiX = transformToDevice.M11;
            DPIUtils._dpiY = transformToDevice.M22;
        }
        public static Point DivideByDPI(Point p)
        {
            return new Point(p.X / DPIUtils.DPIX, p.Y / DPIUtils.DPIY);
        }
        public static Rect DivideByDPI(Rect r)
        {
            return new Rect(r.Left / DPIUtils.DPIX, r.Top / DPIUtils.DPIY, r.Width, r.Height);
        }
    }