webcam类的代码：  
 using System;
 using System.Runtime.InteropServices;namespace webcam
 {
     /** 
     /// avicap 的摘要说明。
     /// 
     public class showVideo
     {
         // showVideo calls
         [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); 
         [DllImport("User32.dll")] public static extern bool SendMessage(IntPtr hWnd, int wMsg, short wParam, FrameEventHandler lParam); 
         [DllImport("User32.dll")] public static extern bool SendMessage(IntPtr hWnd, int wMsg, int wParam, ref BITMAPINFO lParam);
         [DllImport("User32.dll")] public static extern int SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int y, int cx, int cy, int wFlags);
         [DllImport("avicap32.dll")]public static extern int capGetVideoFormat(IntPtr hWnd, IntPtr psVideoFormat, int wSize );        // Constants
         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;
  
         // Structures
         [StructLayout(LayoutKind.Sequential)] public struct VIDEOHDR
         {
             [MarshalAs(UnmanagedType.I4)] public int lpData;
             [MarshalAs(UnmanagedType.I4)] public int dwBufferLength;
             [MarshalAs(UnmanagedType.I4)] public int dwBytesUsed;
             [MarshalAs(UnmanagedType.I4)] public int dwTimeCaptured;
             [MarshalAs(UnmanagedType.I4)] public int dwUser;
             [MarshalAs(UnmanagedType.I4)] public int dwFlags;
             [MarshalAs(UnmanagedType.ByValArray, SizeConst=4)] public int[] dwReserved;
         }        [StructLayout(LayoutKind.Sequential)] public struct BITMAPINFOHEADER
         {
             [MarshalAs(UnmanagedType.I4)] public Int32 biSize ;
             [MarshalAs(UnmanagedType.I4)] public Int32 biWidth ;
             [MarshalAs(UnmanagedType.I4)] public Int32 biHeight ;
             [MarshalAs(UnmanagedType.I2)] public short biPlanes;
             [MarshalAs(UnmanagedType.I2)] public short biBitCount ;
             [MarshalAs(UnmanagedType.I4)] public Int32 biCompression;
             [MarshalAs(UnmanagedType.I4)] public Int32 biSizeImage;
             [MarshalAs(UnmanagedType.I4)] public Int32 biXPelsPerMeter;
             [MarshalAs(UnmanagedType.I4)] public Int32 biYPelsPerMeter;
             [MarshalAs(UnmanagedType.I4)] public Int32 biClrUsed;
             [MarshalAs(UnmanagedType.I4)] public Int32 biClrImportant;
         }         [StructLayout(LayoutKind.Sequential)] public struct BITMAPINFO
         {
             [MarshalAs(UnmanagedType.Struct, SizeConst=40)] public BITMAPINFOHEADER bmiHeader;
             [MarshalAs(UnmanagedType.ByValArray, SizeConst=1024)] public Int32[] bmiColors;
         }
  
         public delegate void FrameEventHandler(IntPtr lwnd, IntPtr lpVHdr);
  
         // Public methods
         public static object GetStructure(IntPtr ptr,ValueType structure)
         {
             return Marshal.PtrToStructure(ptr,structure.GetType());
         }
  
         public static object GetStructure(int ptr,ValueType structure)
         {
             return GetStructure(new IntPtr(ptr),structure);
         }
  
         public static void Copy(IntPtr ptr,byte[] data)
         {
             Marshal.Copy(ptr,data,0,data.Length);
         }
  
         public static void Copy(int ptr,byte[] data)
         {
             Copy(new IntPtr(ptr),data);
         }
  
         public static int SizeOf(object structure)
         {
             return Marshal.SizeOf(structure); 
         }
     }    //Web Camera Class
     public class WebCamera
     {
         // Constructur
         public WebCamera(IntPtr handle, int width,int height)
         {
             mControlPtr = handle;
             mWidth = width;
             mHeight = height;
         } 
         // delegate for frame callback
         public delegate void RecievedFrameEventHandler(byte[] data);
         public event RecievedFrameEventHandler RecievedFrame;
  
         private IntPtr lwndC; // Holds the unmanaged handle of the control
         private IntPtr mControlPtr; // Holds the managed pointer of the control
         private int mWidth;
         private int mHeight;
  
         private showVideo.FrameEventHandler mFrameEventHandler; // Delegate instance for the frame callback - must keep alive! gc should NOT collect it
         // Close the web camera
         public void CloseWebcam()
         {
             this.capDriverDisconnect(this.lwndC);
         }
  
         // start the web camera
         public void StartWebCam()
         {
             byte[] lpszName = new byte[100];
             byte[] lpszVer = new byte[100];
  
             showVideo.capGetDriverDescriptionA(0, lpszName, 100,lpszVer, 100);
             this.lwndC = showVideo.capCreateCaptureWindowA(lpszName, showVideo.WS_VISIBLE + showVideo.WS_CHILD, 0, 0, mWidth, mHeight, mControlPtr, 0);
  
             if (this.capDriverConnect(this.lwndC, 0))
             {
                 this.capPreviewRate(this.lwndC, 66);
                 this.capPreview(this.lwndC, true);
                 showVideo.BITMAPINFO bitmapinfo = new showVideo.BITMAPINFO(); 
                 bitmapinfo.bmiHeader.biSize = showVideo.SizeOf(bitmapinfo.bmiHeader);
                 bitmapinfo.bmiHeader.biWidth = 352;
                 bitmapinfo.bmiHeader.biHeight = 288;
                 bitmapinfo.bmiHeader.biPlanes = 1;
                 bitmapinfo.bmiHeader.biBitCount = 24;
                 this.capSetVideoFormat(this.lwndC, ref bitmapinfo, showVideo.SizeOf(bitmapinfo));
                 this.mFrameEventHandler = new showVideo.FrameEventHandler(FrameCallBack);
                 this.capSetCallbackOnFrame(this.lwndC, this.mFrameEventHandler);
                 showVideo.SetWindowPos(this.lwndC, 0, 0, 0, mWidth , mHeight , 6);
             } 
         }        // private functions
         private bool capDriverConnect(IntPtr lwnd, short i)
         {
             return showVideo.SendMessage(lwnd, showVideo.WM_CAP_DRIVER_CONNECT, i, 0);
         }
         private bool capDriverDisconnect(IntPtr lwnd)
         {
             return showVideo.SendMessage(lwnd, showVideo.WM_CAP_DRIVER_DISCONNECT, 0, 0);
         }
         private bool capPreview(IntPtr lwnd, bool f)
         {return showVideo.SendMessage(lwnd, showVideo.WM_CAP_SET_PREVIEW , f, 0);}        private bool capPreviewRate(IntPtr lwnd, short wMS)
         {
             return showVideo.SendMessage(lwnd, showVideo.WM_CAP_SET_PREVIEWRATE, wMS, 0);
         }
  
         private bool capSetCallbackOnFrame(IntPtr lwnd, showVideo.FrameEventHandler lpProc)
         {
                 return showVideo.SendMessage(lwnd, showVideo.WM_CAP_SET_CALLBACK_FRAME, 0, lpProc);
         }        private bool capSetVideoFormat(IntPtr hCapWnd, ref showVideo.BITMAPINFO BmpFormat, int CapFormatSize)
         {
             return showVideo.SendMessage(hCapWnd, showVideo.WM_CAP_SET_VIDEOFORMAT, CapFormatSize, ref BmpFormat);
         }        private void FrameCallBack(IntPtr lwnd, IntPtr lpVHdr)
         {
             showVideo.VIDEOHDR videoHeader = new showVideo.VIDEOHDR();
             byte[] VideoData;
             videoHeader = (showVideo.VIDEOHDR)showVideo.GetStructure(lpVHdr,videoHeader);
             VideoData = new byte[videoHeader.dwBytesUsed];
             showVideo.Copy(videoHeader.lpData ,VideoData);
             if (this.RecievedFrame != null)
                 this.RecievedFrame (VideoData);
         }
     }}
 下面是实现的代码
 using System;
 using System.Drawing;
 using System.Collections;
 using System.ComponentModel;
 using System.Windows.Forms;
 using System.Data;
 using webcam;namespace webcam
 {
 /** 
 /// Form1 的摘要说明。
 /// 
 public class Form1 : System.Windows.Forms.Form
 {
 private System.Windows.Forms.Panel panelPreview;
 private System.Windows.Forms.Button b_play;
 private System.Windows.Forms.Button b_stop;
 /** 
 /// 必需的设计器变量。
 /// 
 private System.ComponentModel.Container components = null;
  WebCamera wc;public Form1()
 {
 //
 // Windows 窗体设计器支持所必需的
 //
 InitializeComponent();//
 // TODO: 在 InitializeComponent 调用后添加任何构造函数代码
 //
 }/** 
 /// 清理所有正在使用的资源。
 /// 
 protected override void Dispose( bool disposing )
 {
 if( disposing )
 {
 if (components != null) 
 {
 components.Dispose();
 }
 }
 base.Dispose( disposing );
 }Windows 窗体设计器生成的代码#region Windows 窗体设计器生成的代码
 /** 
 /// 设计器支持所需的方法 - 不要使用代码编辑器修改
 /// 此方法的内容。
 /// 
 private void InitializeComponent()
 {
 this.b_play = new System.Windows.Forms.Button();
 this.panelPreview = new System.Windows.Forms.Panel();
 this.b_stop = new System.Windows.Forms.Button();
 this.SuspendLayout();
 // 
 // b_play
 // 
 this.b_play.Location = new System.Drawing.Point(280, 368);
 this.b_play.Name = "b_play";
 this.b_play.TabIndex = 0;
 this.b_play.Text = "&Play";
 this.b_play.Click += new System.EventHandler(this.button1_Click);
 // 
 // panelPreview
 // 
 this.panelPreview.Location = new System.Drawing.Point(8, 8);
  = "panelPreview";
 this.panelPreview.Size = new System.Drawing.Size(344, 272);
 this.panelPreview.TabIndex = 1;
 // 
 // b_stop
 // 
 this.b_stop.Enabled = false;
 this.b_stop.Location = new System.Drawing.Point(360, 368);
 this.b_stop.Name = "b_stop";
 this.b_stop.TabIndex = 2;
 this.b_stop.Text = "&Stop";
 this.b_stop.Click += new System.EventHandler(this.b_stop_Click);
 // 
 // Form1
 // 
 this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
 this.ClientSize = new System.Drawing.Size(464, 413);
 this.Controls.Add(this.b_stop);
 this.Controls.Add(this.panelPreview);
 this.Controls.Add(this.b_play);
 this.MaximizeBox = false;
 this.MinimizeBox = false;
  = "Form1";
 this.Text = "GoodView test Web Camera";
 this.Load += new System.EventHandler(this.Form1_Load);
 this.ResumeLayout(false);
 }
 #endregion/** 
 /// 应用程序的主入口点。
 /// 
 [STAThread]
 static void Main() 
 {
 Application.Run(new Form1());
 }private void Form1_Load(object sender, System.EventArgs e)
 {
 b_play.Enabled = false;
 b_stop.Enabled = true;
 panelPreview.Size = new Size(330,330);
 wc = new WebCamera( panelPreview.Handle,panelPreview.Width,panelPreview.Height);
 wc.StartWebCam();
 }private void button1_Click(object sender, System.EventArgs e)
 {
 b_play.Enabled = false;
 b_stop.Enabled = true;
 panelPreview.Size = new Size(330,330);
 wc = new WebCamera( panelPreview.Handle,panelPreview.Width,panelPreview.Height);
 wc.StartWebCam();
 }private void b_stop_Click(object sender, System.EventArgs e)
 {
 b_play.Enabled = true;
 b_stop.Enabled = false;
 wc.CloseWebcam();
 }
 }
 }