TwipsPerPixel

当把VB程式转成.net 时，其座标会经常转换，用下面的程式来解决这个问题．

 

 const long HWND_DESKTOP = 0;
        const int LOGPIXELSX = 88;
        const int LOGPIXELSY = 90;

  [DllImport("gdi32.dll ")]
        private static extern int GetDeviceCaps(IntPtr hdc, int Index);
        [DllImport("User32.dll")]
        static extern IntPtr GetDC(IntPtr Hwnd); 
        [DllImport("User32.dll")]
        static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);

   private double TwipsPerPixelX()
        {
            IntPtr lngDC = GetDC(IntPtr.Zero);
            double perPixel= 1440 / GetDeviceCaps(lngDC, LOGPIXELSX);
            ReleaseDC(IntPtr.Zero, lngDC);
            return perPixel;
        }

        private double TwipsPerPixelY()
        {
            IntPtr lngDC = GetDC(IntPtr.Zero);
            double perPixel = 1440 / GetDeviceCaps(lngDC, LOGPIXELSY);
            ReleaseDC(IntPtr.Zero, lngDC);
            return perPixel;
        }