[DllImport("gdi32.dll",EntryPoint="BitBlt")]

        public static extern bool BitBlt(IntPtr hdcDest,int xDest,int yDest,int

            wDest,int hDest,IntPtr hdcSource,int xSrc,int ySrc,int RasterOp);

        [DllImport ("gdi32.dll",EntryPoint="CreateCompatibleBitmap")]

        public static extern IntPtr CreateCompatibleBitmap(IntPtr hdc,int nWidth, int nHeight);

        [DllImport ("gdi32.dll",EntryPoint="CreateCompatibleDC")]

        public static extern IntPtr CreateCompatibleDC(IntPtr hdc);

        [DllImport ("gdi32.dll",EntryPoint="SelectObject")]

        public static extern IntPtr SelectObject(IntPtr hdc,IntPtr bmp);

        #endregion

    }

    // 使用User32 APIs

    public class PlatformInvokeUSER32

    {

        #region Class Variables

        public  const int SM_CXSCREEN=0;

        public  const int SM_CYSCREEN=1;

        #endregion   

        #region Class Functions

        [DllImport("user32.dll", EntryPoint="GetDesktopWindow")]

        public static extern IntPtr GetDesktopWindow();

        [DllImport("user32.dll",EntryPoint="GetDC")]

        public static extern IntPtr GetDC(IntPtr ptr);

        [DllImport("user32.dll",EntryPoint="GetSystemMetrics")]

        public static extern int GetSystemMetrics(int abc);

        [DllImport("user32.dll",EntryPoint="GetWindowDC")]

        public static extern IntPtr GetWindowDC(Int32 ptr);

        [DllImport("user32.dll",EntryPoint="ReleaseDC")]

        public static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hDc);

        [DllImport("user32.dll", EntryPoint="ShowWindow", CharSet=CharSet.Auto)]

　　    public static extern int ShowWindow(IntPtr hwnd,int nCmdShow);

        #endregion

    }