C#实现控制摄像头的类

/// <summary>
/// 一个控制摄像头的类
/// </summary>
public class Pick
{
  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 bool bStat = false;
  private IntPtr mControlPtr;
  private int mWidth;
  private int mHeight;
  private int mLeft;
  private int mTop;
  /// <summary>
  /// 初始化摄像头
  /// </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 Pick(IntPtr handle, int left, int top, int width, int height)
  {
   mControlPtr = handle;
   mWidth = width;
   mHeight = height;
   mLeft = left;
   mTop = top;
  }
  [DllImport("avicap32.dll")]
  private static extern IntPtr capCreateCaptureWindowA(byte[] lpszWindowName, int dwStyle, int x, int y, int nWidth, int nHeight, IntPtr hWndParent, int nID);
  [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, int wParam, long lParam);
  /// <summary>
  /// 开始显示图像
  /// </summary>
  public void Start()
  {
   if (bStat)
    return;
   bStat = 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, 0, 0);
    SendMessage(hWndC, WM_CAP_SET_CALLBACK_ERROR, 0, 0);
    SendMessage(hWndC, WM_CAP_SET_CALLBACK_STATUSA, 0, 0);
    SendMessage(hWndC, WM_CAP_DRIVER_CONNECT, 0, 0);
    SendMessage(hWndC, WM_CAP_SET_SCALE, 1, 0);
    SendMessage(hWndC, WM_CAP_SET_PREVIEWRATE, 66, 0);
    SendMessage(hWndC, WM_CAP_SET_OVERLAY, 1, 0);
    SendMessage(hWndC, WM_CAP_SET_PREVIEW, 1, 0);
   }
   return;
  }
  /// <summary>
  /// 停止显示
  /// </summary>
  public void Stop()
  {
   SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, 0, 0);
   bStat = 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);
   SendMessage(hWndC, WM_CAP_SAVEDIB, 0, hBmp.ToInt64());
  }
  /// <summary>
  /// 录像
  /// </summary>
  /// <param name="path">要保存avi文件的路径</param>
  public void Kinescope(string path)
  {
   IntPtr hBmp = Marshal.StringToHGlobalAnsi(path);
   SendMessage(hWndC, WM_CAP_FILE_SET_CAPTURE_FILEA, 0, hBmp.ToInt64());
   SendMessage(hWndC, WM_CAP_SEQUENCE, 0, 0);
  }
  /// <summary>
  /// 停止录像
  /// </summary>
  public void StopKinescope()
  {
   SendMessage(hWndC, WM_CAP_STOP, 0, 0);
  }
}