发布一个屏幕捕捉类

前做时间完成了一个LED点陈显示屏系统，
其中有个功能是需要动态捕捉屏幕上显示的内容发送到LED屏，
现成整理出了一个屏幕捕捉类。如下:

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Drawing.Imaging;
using System.Drawing;

namespace wuChang
{
    /// <summary>
    /// 屏幕捕捉类
   /// 无常作品
    /// msn:wuChangx@hotmail.com
    /// QQ: 3263262
    /// http://www.cnblogs.com/wuchang
    /// </summary>
    internal class ScreenCapture : IDisposable
    {
        private static ScreenCapture instance = null;

        internal static ScreenCapture Instance
        {
            get
            {
                if (instance == null)
                {
                    instance = new ScreenCapture();
                }
                return ScreenCapture.instance;
            }
        }
        int hdcSrc,
            hdcDest;
        private ScreenCapture()
        {
            hdcSrc = User32.GetWindowDC(User32.GetDesktopWindow());
            hdcDest = GDI32.CreateCompatibleDC(hdcSrc);
        }
        /// <summary>
        /// 屏幕捕捉
        /// </summary>
        /// <param name="rct">要捕捉的桌面区域</param>
        /// <returns>捕获后的图形</returns>
        internal Bitmap Capture(Rectangle rct)
        {
            int hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc, rct.Width, rct.Height);

            GDI32.SelectObject(hdcDest, hBitmap);
            GDI32.BitBlt(hdcDest, 0, 0, rct.Width, rct.Height,
                            hdcSrc, rct.Left, rct.Top, 0x00CC0020);
            Bitmap image = new Bitmap(Image.FromHbitmap(new IntPtr(hBitmap)),
                     Image.FromHbitmap(new IntPtr(hBitmap)).Width,
                     Image.FromHbitmap(new IntPtr(hBitmap)).Height);

            GDI32.DeleteObject(hBitmap);
            return image;

        }

        #region IDisposable Members

        public void Dispose()
        {
            User32.ReleaseDC(User32.GetDesktopWindow(), hdcSrc);
            GDI32.DeleteDC(hdcDest);
        }
        #endregion


    }
    //下面二个类来自:http://www.c-sharpcorner.com/Code/2003/Dec/ScreenCapture.asp

    class GDI32
    {
        [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);
    }

    class User32
    {
        [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);
    }


}

使用方法：
1、捕捉主显示器的全屏内容

wuChang.ScreenCapture.Instance.Capture(Screen.PrimaryScreen.Bounds).Save(@"c:\aa.bmp", ImageFormat.Bmp);

2、捕捉当前窗口内容

wuChang.ScreenCapture.Instance.Capture( this.Bounds ).Save(@"c:\aa.bmp", ImageFormat.Bmp);