winform 调用摄像头扫码识别二维码的实现步骤

private void LoadTitleCenterData()
 {
      string titleMsg ="二维码识别主界面";
      Graphics g = this.CreateGraphics();
      Double startingPoint = (this.Width / 2) - (g.MeasureString(titleMsg, this.Font).Width / 2);
      Double widthOfASpace = g.MeasureString(" ", this.Font).Width;
      String tmp = " ";
      Double tmpWidth = 0;

      while ((tmpWidth + widthOfASpace) < startingPoint)
      {
        tmp += " ";
        tmpWidth += widthOfASpace;
      }
      this.Text = tmp + titleMsg;
 }

最大最小化禁用：

public Form1()
{
  this.MinimizeBox = false;
  this.MaximizeBox = false;
  InitializeComponent();
  LoadTitleCenterData();
}

 private AForge.Video.DirectShow.FilterInfoCollection _videoDevices;//摄像设备
 System.Timers.Timer timer;//定时器
 CameraHelper _cameraHelper = new CameraHelper();//视屏设备操作类

窗体Load事件中获取拍照设备列表，并将第一个设备作为摄像设备（如有前后两个或多个摄像头，自己去改一下代码，设置成可以选择的，在CameraHelper中的CreateFilterInfoCollection()中）：

private void CameraQR_Load(object sender, EventArgs e)
{
      // 获取视频输入设备
      _videoDevices = _cameraHelper.CreateFilterInfoCollection();//获取拍照设备列表
      if (_videoDevices.Count == 0)
      {
        MessageBox.Show("无设备");
        this.Dispose();
        this.Close();
        return;
      }
      resultStr = "";//二维码识别字符串清空
      _cameraHelper.ConnectDevice(videoSourcePlayer1);//连接打开设备
}

组件初始化完成之后，添加一个定时任务，用来阶段性识别摄像设备中的图片资源，我写的是每200毫秒去识别一次，如果图片中有二维码，就识别二维码；识别成功之后，关闭窗体，将识别结果返回给上一个界面,此处需要一个有识别二维码程序包

使用Nuget添加引用，搜索ZXing，将如下程序包引入：

public CameraQR()
{
  this.MinimizeBox = false;
  this.MaximizeBox = false;
  InitializeComponent();
  LoadTitleCenterData();
  CheckForIllegalCrossThreadCalls = false;//多线程中访问窗体控件资源不会异常
  AddTimer();//定时识别图片
}

private void AddTimer()
{
 timer = new System.Timers.Timer();
 timer.Enabled = true;
 timer.Interval = 200;
 timer.Start();
 timer.Elapsed += new ElapsedEventHandler(PicToQRCode);
}
private void PicToQRCode(object sender, ElapsedEventArgs e)
{
      if (_cameraHelper.img == null)
        return;
      BinaryBitmap bitmap = null;
      try
      {
        MemoryStream ms = new MemoryStream();
        _cameraHelper.img.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);
        byte[] bt = ms.GetBuffer();
        ms.Close();
        LuminanceSource source = new RGBLuminanceSource(bt, _cameraHelper.img.Width, _cameraHelper.img.Height);
        bitmap = new BinaryBitmap(new ZXing.Common.HybridBinarizer(source));
      }
      catch (Exception ex)
      {
        return;
      }

      Result result=null;
      try
      {
        //开始解码
        result = new MultiFormatReader().decode(bitmap);
      }
      catch (ReaderException ex)
      {
        resultStr = ex.ToString();
      }
      if (result != null)
      {
        resultStr = result.Text;
        this.DialogResult = DialogResult.OK;
        this.Close();
      }}

private void CameraQR_FormClosing(object sender, FormClosingEventArgs e)
{
   if (timer != null)
   {
     timer.Dispose();
   }
    _cameraHelper.CloseDevice();
 }

public class CameraHelper
{
  public FilterInfoCollection _videoDevices;//本机摄像硬件设备列表
  public VideoSourcePlayer _videoSourcePlayer;//视频画布
  public Bitmap img = null;//全局变量，保存每一次捕获的图像
  public System.Drawing.Image CaptureImage(VideoSourcePlayer sourcePlayer = null)
  {

    if (sourcePlayer == null || sourcePlayer.VideoSource == null)
    {
      if (_videoSourcePlayer == null)
        return null;
      else
      {
        sourcePlayer = _videoSourcePlayer;
      }
    }

    try
    {
      if (sourcePlayer.IsRunning)
      {
        System.Drawing.Image bitmap = sourcePlayer.GetCurrentVideoFrame();
        return bitmap;
      }
      return null;

    }
    catch (Exception ex)
    {
      return null;
    }
  }

  public FilterInfoCollection CreateFilterInfoCollection()
  {
    if (_videoDevices != null)
      return _videoDevices;
    _videoDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice);
    return _videoDevices;
  }

  public VideoCaptureDevice ConnectDevice(VideoSourcePlayer videoSourcePlayer, FilterInfo filterInfo = null)
  {
    VideoCaptureDevice videoSource = new VideoCaptureDevice();
    if (filterInfo == null)
    {
      videoSource = new VideoCaptureDevice(_videoDevices[_videoDevices.Count - 1].MonikerString);
    }
    else
    {
      videoSource = new VideoCaptureDevice(filterInfo.MonikerString);
    }

    videoSource.NewFrame += new NewFrameEventHandler(video_NewFrame);
    videoSourcePlayer.VideoSource = videoSource;
    videoSourcePlayer.Start();
    _videoSourcePlayer = videoSourcePlayer;
    return videoSource;
  }

  private void video_NewFrame(object sender, NewFrameEventArgs eventArgs)
  {
    img = (Bitmap)eventArgs.Frame.Clone();
  }

  public void CloseDevice(VideoSourcePlayer videoSourcePlayer = null)
  {
    if (videoSourcePlayer == null)
    {
      if (_videoSourcePlayer == null)
        return;
      _videoSourcePlayer.SignalToStop();
    }
    else
    {
      videoSourcePlayer.SignalToStop();
    }
  }
}