C#截取屏幕

    /// <summary>
    /// 截取屏幕
    /// </summary>
    class ScreenGrab
    {
        #region Functional imports for ScreenGrab functionality
        [DllImport("GDI32.dll")]
        public static extern bool BitBlt(int hdcDest, int nXDest, int nYDest, int nWidth, int nHeight, int hdcSrc, int nXSrc, int nYSrc, int dwRop);
        [DllImport("GDI32.dll")]
        public static extern int CreateCompatibleBitmap(int hdc, int nWidth, int nHeight);
        [DllImport("GDI32.dll")]
        public static extern int CreateCompatibleDC(int hdc);
        [DllImport("GDI32.dll")]
        public static extern bool DeleteDC(int hdc);
        [DllImport("GDI32.dll")]
        public static extern bool DeleteObject(int hObject);
        [DllImport("GDI32.dll")]
        public static extern int GetDeviceCaps(int hdc, int nIndex);
        [DllImport("GDI32.dll")]
        public static extern int SelectObject(int hdc, int hgdiobj);
        [DllImport("User32.dll")]
        public static extern int GetDesktopWindow();
        [DllImport("User32.dll")]
        public static extern int GetWindowDC(int hWnd);
        [DllImport("User32.dll")]
        public static extern int ReleaseDC(int hWnd, int hDC);
        #endregion

        // Captures the current on-screen representation using Windows API calls
        public Bitmap CaptureScreen()
        {
            // Provides a pointer to the visual representation of the desktop window
            int source = GetWindowDC(GetDesktopWindow());
            // Secures the image using CreateCompatibleBitmap
            int bitmap = CreateCompatibleBitmap(source, GetDeviceCaps(source, 8), GetDeviceCaps(source, 10));

            int destination = CreateCompatibleDC(source);

            SelectObject(destination, bitmap);
            BitBlt(destination, 0, 0, GetDeviceCaps(source, 8), GetDeviceCaps(source, 10), source, 0, 0, 0x00CC0020);
            Bitmap image = GetImage(bitmap);
            Cleanup(bitmap, source, destination);
            return image;
        }

        private void Cleanup(int bitmap, int source, int destination)
        {
            ReleaseDC(GetDesktopWindow(), source);
            DeleteDC(destination);
            DeleteObject(bitmap);
        }

        private Bitmap GetImage(int hBitmap)
        {
            Bitmap image = new Bitmap(Image.FromHbitmap(new IntPtr(hBitmap)), Image.FromHbitmap(new IntPtr(hBitmap)).Width,
                           Image.FromHbitmap(new IntPtr(hBitmap)).Height);
            return image;
        }
    }