EmguCV ImageGrabbed Event WPF App

问题

I have problems with the following code

namespace MyApp
{    
    public partial class PhotoWindow : Window
    {
        private Capture _capture;

        public PhotoWindow ()
        {
            InitializeComponent();    
            _capture = new Capture();

            if (_capture != null)
            {
                //<Image> in XAML
                CaptureSource.Width = 150;
                CaptureSource.Height = 180;

                _capture.ImageGrabbed += ProcessFrame;
                _capture.Start();                
            }

            Activated += (s, e) => _capture.Start();
            Closing += (s, e) =>
            {
                if (_capture == null) return;
                _capture.Stop();                
                _capture.Dispose();
            };
        }

        private void ProcessFrame(object sender, EventArgs e)
        {
            try
            {
                Image<Bgr, Byte> frame = _capture.RetrieveBgrFrame();                   
                CaptureSource.Source = Helper.ToBitmapSource(frame);
            }
            catch (Exception exception)
            {

                System.Windows.MessageBox.Show(exception.ToString());
            }
        }

    }
}

when I run the application I get the exception System.InvalidOperationException: The thread that this call can not access this object because the owner is another thread on line CaptureSource.Source = Helper.ToBitmapSource(frame);

As I can solve this?

回答1:

It seems that ImageGrabbed event is raised from Capture's background thread and because of that your handler is running in that thread rather then the UI thread of your window.

You can use the Dispatcher to invoke code in the control's UI thread.

CaptureSource.Dispatcher.Invoke(() =>
{
   Image<Bgr, Byte> frame = _capture.RetrieveBgrFrame();                   
   CaptureSource.Source = Helper.ToBitmapSource(frame);
});

回答2:

I use Emgu.CV.UI.ImageBox in the UI to display the Image<,> frame from the Capture

Image<Bgr, Byte> frame = _capture.RetrieveBgrFrame();    
imageBox.Invoke(new Action(() => imageBox.Image = frame));

来源：https://stackoverflow.com/questions/11402314/emgucv-imagegrabbed-event-wpf-app

标签

multithreading

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