private void InitializeGraphics(GraphicsContext gc)
{
GraphicsContext = gc;
ScreenWidth = GraphicsContext.Screen.Width;
ScreenHeight = GraphicsContext.Screen.Height;
ScreenRectangle = GraphicsContext.Screen.Rectangle;
DevicePpiX = SystemParameters.DisplayDpiX;
DevicePpiY = SystemParameters.DisplayDpiY;
DeviceSizeWidth = (Single)Math.Round(ScreenWidth / DevicePpiX, 1);
DeviceSizeHeight = (Single)Math.Round(ScreenHeight / DevicePpiY, 1);
DevicePpi = CalculateDevicePpi();
DeviceSize = CalculateDeviceSize();
}