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);
  }
}