c# winform 访问摄像头照片

public Form1()
        {
            InitializeComponent();
        }
        cVideo video;
        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            video = new cVideo(pictureBox1.Handle, pictureBox1.Width, pictureBox1.Height);

            video.StartWebCam();

        }

        private void button2_Click(object sender, EventArgs e)
        {
            video.CloseWebcam();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            video.GrabImage(video.GetIntPtr(), "d:\\a.bmp");
        }
    }

    public class VideoAPI
    {

        // 视频API调用

        [DllImport("avicap32.dll")]

        public static extern IntPtr capCreateCaptureWindowA(byte[] lpszWindowName,

            int dwStyle, int x, int y, int nWidth, int nHeight,

            IntPtr hWndParent, int nID);

        [DllImport("avicap32.dll")]

        public static extern bool capGetDriverDescriptionA(short wDriver,

            byte[] lpszName, int cbName, byte[] lpszVer, int cbVer);

        [DllImport("User32.dll")]

        public static extern bool SendMessage(IntPtr hWnd, int wMsg,

            bool wParam, int lParam);

        [DllImport("User32.dll")]

        public static extern bool SendMessage(IntPtr hWnd, int wMsg,

            short wParam, int lParam);

        // 常量

        public const int WM_USER = 0x400;

        public const int WS_CHILD = 0x40000000;

        public const int WS_VISIBLE = 0x10000000;

        public const int SWP_NOMOVE = 0x2;

        public const int SWP_NOZORDER = 0x4;

        public const int WM_CAP_DRIVER_CONNECT = WM_USER + 10;

        public const int WM_CAP_DRIVER_DISCONNECT = WM_USER + 11;

        public const int WM_CAP_SET_CALLBACK_FRAME = WM_USER + 5;

        public const int WM_CAP_SET_PREVIEW = WM_USER + 50;

        public const int WM_CAP_SET_PREVIEWRATE = WM_USER + 52;

        public const int WM_CAP_SET_VIDEOFORMAT = WM_USER + 45;

        public const int WM_CAP_START = WM_USER;

        public const int WM_CAP_SAVEDIB = WM_CAP_START + 25;

    }

    public class cVideo
    {

        private IntPtr lwndC;       //保存无符号句柄

        private IntPtr mControlPtr; //保存管理指示器

        private int mWidth;

        private int mHeight;

        public cVideo(IntPtr handle, int width, int height)
        {

            mControlPtr = handle; //显示视频控件的句柄

            mWidth = width;      //视频宽度

            mHeight = height;    //视频高度

        }

        /// <summary>

        /// 打开视频设备

        /// </summary>

        public void StartWebCam()
        {

            byte[] lpszName = new byte[100];

            byte[] lpszVer = new byte[100];

            VideoAPI.capGetDriverDescriptionA(0, lpszName, 100, lpszVer, 100);

            this.lwndC = VideoAPI.capCreateCaptureWindowA(lpszName,

                VideoAPI.WS_CHILD | VideoAPI.WS_VISIBLE, 0, 0,

                mWidth, mHeight, mControlPtr, 0);

            if (VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_DRIVER_CONNECT, 0, 0))
            {

                VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SET_PREVIEWRATE, 100, 0);

                VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SET_PREVIEW, true, 0);

            }

        }


        public IntPtr GetIntPtr()
        {
            byte[] lpszName = new byte[100];

            return VideoAPI.capCreateCaptureWindowA(lpszName,

               VideoAPI.WS_CHILD | VideoAPI.WS_VISIBLE, 0, 0,

               mWidth, mHeight, mControlPtr, 0);
        }
        /// <summary>

        /// 关闭视频设备

        /// </summary>

        public void CloseWebcam()
        {

            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_DRIVER_DISCONNECT, 0, 0);

        }

        ///   <summary>  

        ///   拍照

        ///   </summary>  

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

        public void GrabImage(IntPtr hWndC, string path)
        {

            IntPtr hBmp = Marshal.StringToHGlobalAnsi(path);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SAVEDIB, 0, hBmp.ToInt32());

        }



    }

怎么获取不到图像？？？？？

先不要那么复杂，就执行你的连接摄像头打开显示在图片框的代码，能不能执行，摄像头驱动有没有装好，摄像头有没有插好。

我的是笔记本，自带摄像头，点击打开后，摄像头的灯都开了的，但图片框变成黑色了

用第三方程序能看到图像么？另外系统中同时只能有一个程序访问摄像头。看看别的程序是不是关了。
最后，检查摄像头是否被物体遮挡

this.lwndC = VideoAPI.capCreateCaptureWindowA(lpszName,

            VideoAPI.WS_CHILD | VideoAPI.WS_VISIBLE, 0, 0,

            mWidth, mHeight, mControlPtr, 0);

                            调试下这里，返回什么

if (VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_DRIVER_CONNECT, 0, 0))
之后走入了判断分支了么？

说明摄像头是可以工作的，代码也没有问题，你重启下电脑再试试，或者换一个摄像头看看