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    internal class ScreenCapture
    {
        /// <summary>
        /// Creates an Image object containing a screen shot of the entire desktop
        /// </summary>
        /// <returns></returns>
        public Bitmap CaptureScreen()
        {
            return CaptureWindow(User32.GetDesktopWindow());
        }

        /// <summary>
        /// Creates an Image object containing a screen shot of a specific window
        /// </summary>
        /// <param name="handle">The handle to the window.
        /// (In windows forms, this is obtained by the Handle property)</param>
        /// <returns></returns>
        public Bitmap CaptureWindow(IntPtr handle)
        {
            // get the size
            User32.RECT windowRect = new User32.RECT();
            User32.GetWindowRect(handle, ref windowRect);
            int width = windowRect.right - windowRect.left;
            int height = windowRect.bottom - windowRect.top;
            return CaptureWindow(handle, 0, 0, width, height, true);
        }

        public Bitmap CaptureWindow(IntPtr handle, int x, int y, int width, int height, bool hasWindowBorder = false)
        {
            IntPtr hdcSrc = IntPtr.Zero;
            // get te hDC of the target window
            if (hasWindowBorder)
            {
                hdcSrc = User32.GetWindowDC(handle);
            }
            else
            {
                hdcSrc = User32.GetDC(handle);
            }

            // create a device context we can copy to
            IntPtr hdcDest = GDI32.CreateCompatibleDC(hdcSrc);
            // create a bitmap we can copy it to,
            // using GetDeviceCaps to get the width/height
            IntPtr hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc, width, height);
            // select the bitmap object
            IntPtr hOld = GDI32.SelectObject(hdcDest, hBitmap);
            // bitblt over
            GDI32.BitBlt(hdcDest, 0, 0, width, height, hdcSrc, x, y, GDI32.SRCCOPY | GDI32.CAPTUREBLT);
            // restore selection
            GDI32.SelectObject(hdcDest, hOld);
            // clean up
            GDI32.DeleteDC(hdcDest);
            User32.ReleaseDC(handle, hdcSrc);
            // get a .NET image object for it
            Bitmap img = Image.FromHbitmap(hBitmap);
            // free up the Bitmap object
            GDI32.DeleteObject(hBitmap);
            return img;
        }

        /// <summary>
        /// Helper class containing Gdi32 API functions
        /// </summary>
        private class GDI32
        {
            public const int SRCCOPY = 0x00CC0020; // BitBlt dwRop parameter
            public const int CAPTUREBLT = 0x40000000;//包含透明

            [DllImport("gdi32.dll")]
            public static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest,
                int nWidth, int nHeight, IntPtr hObjectSource,
                int nXSrc, int nYSrc, int dwRop);

            [DllImport("gdi32.dll")]
            public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC, int nWidth,
                int nHeight);

            [DllImport("gdi32.dll")]
            public static extern IntPtr CreateCompatibleDC(IntPtr hDC);

            [DllImport("gdi32.dll")]
            public static extern bool DeleteDC(IntPtr hDC);

            [DllImport("gdi32.dll")]
            public static extern bool DeleteObject(IntPtr hObject);

            [DllImport("gdi32.dll")]
            public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
        }

        /// <summary>
        /// Helper class containing User32 API functions
        /// </summary>
        private class User32
        {
            [StructLayout(LayoutKind.Sequential)]
            public struct RECT
            {
                public int left;
                public int top;
                public int right;
                public int bottom;
            }

            [DllImport("user32.dll")]
            public static extern IntPtr GetDesktopWindow();

            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowDC(IntPtr hWnd);

            [DllImport("user32.dll")]
            public static extern IntPtr GetDC(IntPtr hWnd);

            [DllImport("user32.dll")]
            public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDC);

            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowRect(IntPtr hWnd, ref RECT rect);
        }
    }