C# 屏幕捕捉类

在网上搜到的，和大家一起分享

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:[email protected]
     ///  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);
    }


}