c# GTK 2 & 3 conflict when using Emgucv

Question

I found a strange confict when using Emgu with class 'ImageViewer'

When I have no static class member, everything work just fine. for example, code like below

using Emgu.CV;
using Emgu.CV.Util;
using Emgu.CV.UI;

namespace TmpTest
{
    class TmpTest
    {
        private Mat img = new Mat();  // a non-static class member is OKey
        public static void Main(string[] arg)
        {
            SDKWrapper util = new SDKWrapper();
            ImageViewer viewer = new ImageViewer ();
            VideoCapture capture = new VideoCapture ();

            Application.Idle += new EventHandler (delegate(object sender, EventArgs e) {
                Mat read_frame = capture.QueryFrame();
                util.processFrame(read_frame);
                util.drawSkeleton(read_frame);
                viewer.Image = read_frame;
            });
            viewer.ShowDialog ();  
            return;
        }
    }
}

But as soon as I add a static class member, for example, change private Mat img into private static Mat img , I got an runtime error immediately like this

Gtk-ERROR **: GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported

I'm using ubuntu 16.04 and monodevelopment, does anyone knows what had happened and how to solve it?

Answer 1

Emgu CV is a .Net wrapper to OpenCV. Depending on the OpenCV version you use, it can be build against GTK 2 or GTK 3, but usually is against GTK 2. However, an application can't use GTK 2 and GTK 3 at the same time. So I think the OpenCv part uses GTK 2 and you have something else pulling GTK 3. You should check on which libraries the binaries of emgu CV you're using depend.