屏幕抓屏（包括活动窗口，指定区域及全屏等）

using System;
using System.Runtime.InteropServices;
using System.Drawing;

namespace SystemTools
...{
    [StructLayout(LayoutKind.Sequential)]
    public struct RECT
    ...{
        public int left, top, right, bottom;
    }

    /**//// <summary>
    /// 封装API的类
    /// </summary>
    public class APIs
    ...{
        [DllImport("user32.dll")]
        public static extern bool GetCursorPos(ref Point lpPoint);
        [DllImport("user32.dll")]
        public static extern int WindowFormPoint(Point lpPoint);
        [DllImport("user32.dll")]
        public static extern IntPtr GetDesktopWindow();
        [DllImport("user32.dll")]
        public static extern int GetForegroundWindow();
        [DllImport("user32.dll")]
        public static extern int GetWindowRect(int hwnd, ref RECT rc);
        [DllImport("user32.dll")]
        public static extern int GetWindowDC(int hwnd);
        [DllImport("Gdi32.dll")]
        public static extern bool Bitblt(
            IntPtr hdcDest, // 目标设备的句柄
            int nXDest, // 目标对象的左上角的X坐标
            int nYDest, // 目标对象的左上角的X坐标
            int nWidth, // 目标对象的矩形的宽度
            int nHeight, // 目标对象的矩形的长度
            IntPtr hdcSrc, // 源设备的句柄
            int nXSrc, // 源对象的左上角的X坐标
            int nYSrc, // 源对象的左上角的X坐标
            System.Int32 dwRop // 光栅的操作值
            );
        [DllImportAttribute("gdi32.dll")]
        public static extern IntPtr CreateDC(
        string lpszDriver, // 驱动名称
        string lpszDevice, // 设备名称
        string lpszOutput, // 无用，可以设定位"NULL"
        IntPtr lpInitData // 任意的打印机数据
        );

    }
}

 

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Imaging;

namespace SystemTools
...{
    /**//// <summary>
    /// 封装各种抓屏操作的类
    /// </summary>
    public class CatchScreen
    ...{
        /**//// <summary>
        /// 获得屏幕指定区域 
        /// </summary>
        /// <param name="left"></param>
        /// <param name="top"></param>
        /// <param name="width"></param>
        /// <param name="height"></param>
        /// <returns></returns>
        public Bitmap getScreen(int left, int top, int width, int height)
        ...{
            IntPtr dc1 = APIs.CreateDC("DISPLAY", null, null, (IntPtr)null);
            Graphics newGraphics = Graphics.FromHdc(dc1);
            Bitmap img = new Bitmap(width, height, newGraphics);
            Graphics thisGraphics = Graphics.FromImage(img);
            IntPtr dc2 = thisGraphics.GetHdc();
            IntPtr dc3 = newGraphics.GetHdc();
            APIs.Bitblt(dc2, 0, 0, width, height, dc3, left, top, 13369376);
            thisGraphics.ReleaseHdc(dc2);
            newGraphics.ReleaseHdc(dc3);
            return img;
        }

        /**//// <summary>
        /// 获得全屏
        /// </summary>
        /// <returns></returns>
        public Bitmap getFullScreen()
        ...{
            return getScreen(0, 0, Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
        }

        /**//// <summary>
        /// 抓取句柄所指窗口
        /// </summary>
        /// <param name="hwnd"></param>
        /// <returns></returns>
        public Bitmap getScreenFromHandle(int hwnd)
        ...{
            RECT rc = new RECT();
            APIs.GetWindowRect(hwnd, ref rc);
            return getScreen(rc.left, rc.top, rc.right - rc.left, rc.bottom - rc.top);
        }

        /**//// <summary>
        /// 抓取活动窗口
        /// </summary>
        /// <returns></returns>
        public Bitmap getScreenFromActiveWindow()
        ...{
            int handle = APIs.GetForegroundWindow();
            return getScreenFromHandle(handle);
        }

        //保存成各种格式
        public string savepic(Bitmap bmp)
        ...{
            SaveFileDialog saveDialog = new SaveFileDialog();
            saveDialog.Filter = "位图文件 (*.bmp)|*.bmp|jpg文件 (*.jpg)|*.jpg|gif文件 (*.gif)|*.gif|tiff文件 (*.tiff)|*.tiff|"+
            "emf文件 (*.emf)|*.emf|图标文件 (*.ico)|*.ico|wmf文件 (*.wmf)|*.wmf|png文件 (*.png)|*.png";
            saveDialog.DefaultExt="*.bmp";
            if(saveDialog.ShowDialog() == DialogResult.OK)
            ...{
            string ext = saveDialog.FileName.Substring(saveDialog.FileName.Length-4,4);
            switch( ext)
            ...{ 
            case ".bmp":
            bmp.Save(saveDialog.FileName,ImageFormat.Bmp);
            break; 
            case ".gif": 
            bmp.Save(saveDialog.FileName,ImageFormat.Gif);
            break;
            case ".jpg": 
            bmp.Save(saveDialog.FileName,ImageFormat.Jpeg);
            break;
            case ".emf":
            bmp.Save(saveDialog.FileName,ImageFormat.Emf);
            break; 
            case ".ico": 
            bmp.Save(saveDialog.FileName,ImageFormat.Icon);
            break;
            case ".wmf": 
            bmp.Save(saveDialog.FileName,ImageFormat.Wmf);
            break;
            case ".png": 
            bmp.Save(saveDialog.FileName,ImageFormat.Png);
            break;
            case ".tiff": 
            bmp.Save(saveDialog.FileName,ImageFormat.Tiff);
            break;
            default :
            return "";
            } 
            return saveDialog.FileName;
            }
            return "";
        }
    }
}