c# 如何在form中通过摄像头拍照

using System;

using System.Collections.Generic;

using System.Text;

using System.Runtime.InteropServices;



namespace CamTest

{



    //参考AVICap技术

    public class Cam

    {

        private const int WM_USER = 0x400;

        private const int WS_CHILD = 0x40000000;

        private const int WS_VISIBLE = 0x10000000;

        private const int WM_CAP_START = WM_USER;

        private const int WM_CAP_STOP = WM_CAP_START + 68;

        private const int WM_CAP_DRIVER_CONNECT = WM_CAP_START + 10;

        private const int WM_CAP_DRIVER_DISCONNECT = WM_CAP_START + 11;

        private const int WM_CAP_SAVEDIB = WM_CAP_START + 25;

        private const int WM_CAP_GRAB_FRAME = WM_CAP_START + 60;

        private const int WM_CAP_SEQUENCE = WM_CAP_START + 62;

        private const int WM_CAP_FILE_SET_CAPTURE_FILEA = WM_CAP_START + 20;

        private const int WM_CAP_SEQUENCE_NOFILE = WM_CAP_START + 63;

        private const int WM_CAP_SET_OVERLAY = WM_CAP_START + 51;

        private const int WM_CAP_SET_PREVIEW = WM_CAP_START + 50;

        private const int WM_CAP_SET_CALLBACK_VIDEOSTREAM = WM_CAP_START + 6;

        private const int WM_CAP_SET_CALLBACK_ERROR = WM_CAP_START + 2;

        private const int WM_CAP_SET_CALLBACK_STATUSA = WM_CAP_START + 3;

        private const int WM_CAP_SET_CALLBACK_FRAME = WM_CAP_START + 5;

        private const int WM_CAP_SET_SCALE = WM_CAP_START + 53;

        private const int WM_CAP_SET_PREVIEWRATE = WM_CAP_START + 52;



        private IntPtr hWndC;

        private IntPtr mControlPtr;

        private bool bWorkStart = false;

        private int mWidth;

        private int mHeight;

        private int mLeft;

        private int mTop;



        /// <summary>

        /// 初始化显示图像

        /// </summary>

        /// <param name="handle">控件的句柄 </param>

        /// <param name="left">开始显示的左边距 </param>

        /// <param name="top">开始显示的上边距 </param>

        /// <param name="width">要显示的宽度 </param>

        /// <param name="height">要显示的长度 </param>

        public Cam(IntPtr handle, int left, int top, int width, int height)  

        {

            mControlPtr = handle;

            mWidth = width;

            mHeight = height;

            mLeft = left;

            mTop = top;

        }

        // 创建捕捉窗口

        //HWND VFWAPI capCreateCaptureWindow(

        //      LPCSTR lpszWindowName，// 捕捉窗口名字

        //      DWORD dwStyle，// 捕捉窗口的风格

        //      int x，// 窗口左上角x轴坐标

        //      int y，// 窗口左上角y轴坐标

        //      int nWidth，// 窗口的宽度

        //      int nHeight，// 窗口的高度

        //      HWND HWnd，// 父窗口句柄

        //      Int nID// 捕捉窗口的ID号

        //);

        //如果该函数调用成功 则函数返回窗口的句柄 否则函数返回NULL。

        [DllImport("avicap32.dll")]

        private static extern IntPtr capCreateCaptureWindowA(byte[] lpszWindowName, int dwStyle, int x, int y, int nWidth, int nHeight, IntPtr hWndParent, int nID);



    //      视频格式设置对话框

    //    BOOL capDlgVideoFormat( hwnd ); // hwnd：捕捉窗口句柄

    //视频格式设置对话框对于每一个捕捉驱动程序来说，是唯一的。而且，有些驱动程序不一定支持这一功能。应用程序可以通过检测CAPDRIVERCAPS结构的成员变量fHasDlgVideoFormat来判断驱动程序是否支持这一功能。



        [DllImport("avicap32.dll")]

        private static extern int capGetVideoFormat(IntPtr hWnd, IntPtr psVideoFormat, int wSize);

        [DllImport("User32.dll")]

        private static extern bool SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam);



        /// <summary>

        /// 开始显示图像

        /// </summary>

        public void Start()

        {

            if (bWorkStart)

            {

                return;

            }

            bWorkStart = true;

            byte[] lpszName = new byte[100];

            hWndC = capCreateCaptureWindowA(lpszName, WS_CHILD | WS_VISIBLE, mLeft, mTop, mWidth, mHeight, mControlPtr, 0);

            if (hWndC.ToInt32() != 0)

            {

                SendMessage(hWndC, WM_CAP_SET_CALLBACK_VIDEOSTREAM, IntPtr.Zero, IntPtr.Zero);

                SendMessage(hWndC, WM_CAP_SET_CALLBACK_ERROR, IntPtr.Zero, IntPtr.Zero);

                SendMessage(hWndC, WM_CAP_SET_CALLBACK_STATUSA, IntPtr.Zero, IntPtr.Zero);

                SendMessage(hWndC, WM_CAP_DRIVER_CONNECT, IntPtr.Zero, IntPtr.Zero);

                SendMessage(hWndC, WM_CAP_SET_SCALE, (IntPtr)1, IntPtr.Zero);

                SendMessage(hWndC, WM_CAP_SET_PREVIEWRATE, (IntPtr)66, IntPtr.Zero);

                SendMessage(hWndC, WM_CAP_SET_OVERLAY, (IntPtr)1, IntPtr.Zero);

                SendMessage(hWndC, WM_CAP_SET_PREVIEW, (IntPtr)1, IntPtr.Zero);

            }

            return;

        }



        /// <summary>

        /// 停止显示图像

        /// </summary>

        public void Stop()

        {

            SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, IntPtr.Zero, IntPtr.Zero);

            bWorkStart = false;

        }



        /// <summary>

        /// 抓图

        /// </summary>

        /// <param name="path">要保存bmp文件的路径 </param>

        public void GrabImage(string path)

        {

            IntPtr hBmp = Marshal.StringToHGlobalAnsi(path);  //将System.String内容复制到非托管内存当中

            SendMessage(hWndC, WM_CAP_SAVEDIB, IntPtr.Zero, hBmp);

        }



        ///<summary>

        ///录像

        ///</summary>

        ///<param name="path">要保存avi文件的路径</param>

        public void Kinescope(string path)

        {

            IntPtr hCap = Marshal.StringToHGlobalAnsi(path);

            SendMessage(hWndC, WM_CAP_FILE_SET_CAPTURE_FILEA, IntPtr.Zero, hCap);

            SendMessage(hWndC, WM_CAP_SEQUENCE, IntPtr.Zero, hCap);

        }



        ///<summary>

        ///停止录像

        ///</summary>

        public void StopKinescope()

        {

            SendMessage(hWndC, WM_CAP_STOP, IntPtr.Zero, IntPtr.Zero);

        }



    }

}