Gtkmm-3.0 compiled code throwing Gtk+2 symbol error - c++

Question

I'm on Ubuntu 13.10 using gtkmm 3.0 dev package, compiling the following code:
#include <gtkmm.h>
#include <iostream>
#include "opencv2/opencv.hpp"
#include <chrono>
#include <thread>
#include <mutex>
//GASP! global vars!
std::mutex FRAME_MUTEX;
std::thread CV_THREAD;
cv::Mat FRAME, CLEAN;
Glib::Dispatcher dispatcher;
volatile bool THREADRUN;
void cvThread() {
THREADRUN = true;
cv::VideoCapture capture(0);
while(THREADRUN) {
FRAME_MUTEX.lock();
capture >> FRAME;
FRAME_MUTEX.unlock();
dispatcher.emit();
}
}
int main(int argc, char** argv)
{
Gtk::Main gtkMain(argc, argv);
Glib::RefPtr<Gtk::Builder> builder = Gtk::Builder::create_from_file("main_window.glade");
Gtk::Window *mainWindow;
Gtk::Image *cleanDisplay;
Gtk::Image *evmDisplay;
builder->get_widget("main_window", mainWindow);
builder->get_widget("clean_display", cleanDisplay);
builder->get_widget("evm_display", evmDisplay);
dispatcher.connect([&]() {
FRAME_MUTEX.lock();
cv::cvtColor(FRAME, CLEAN, CV_BGR2RGB);
cleanDisplay->set(Gdk::Pixbuf::create_from_data(CLEAN.data, Gdk::COLORSPACE_RGB, false, 8, CLEAN.cols, CLEAN.rows, CLEAN.step));
cleanDisplay->queue_draw();
FRAME_MUTEX.unlock();
});
CV_THREAD = std::thread(&cvThread);
gtkMain.run(*mainWindow);
return 0;
}
Using the command:
$ g++ test.cpp -o uitest `pkg-config --cflags --libs gtkmm-3.0 opencv` -std=c++11
Compilation works fine, but when I run the executable, it fails with the following error:
(uitest:20300): Gtk-ERROR **: GTK+ 2.x symbols detected.
Using GTK+ 2.x and GTK+ 3 in the same process is not supported
Trace/breakpoint trap (core dumped)
This is my first attempt to delve into using gtkmm, and I don't have the foggiest idea of where to go to start debugging. I checked the glade file, and it has an xml comment at the top indicating that gtk+3 is required by the contents of that file. The answer here didn't help me much; I got the following output from following those instructions:
-lgtkmm-3.0 -latkmm-1.6 -lgdkmm-3.0 -lgiomm-2.4 -lpangomm-1.4 -lgtk-3 -lglibmm-2.4
-lcairomm-1.0 -lgdk-3 -latk-1.0 -lgio-2.0 -lpangocairo-1.0 -lgdk_pixbuf-2.0
-lcairo-gobject -lpango-1.0 -lcairo -lsigc-2.0 -lgobject-2.0 -lglib-2.0
-lopencv_calib3d -lopencv_contrib -lopencv_core -lopencv_features2d -lopencv_flann
-lopencv_gpu -lopencv_highgui -lopencv_imgproc -lopencv_legacy -lopencv_ml
-lopencv_objdetect -lopencv_ocl -lopencv_photo -lopencv_stitching -lopencv_superres
-lopencv_ts -lopencv_video -lopencv_videostab
Any suggestions on how to fix this issue?

Answer 1

Till the OpenCV 3 gets released you can use Gtk::Image or Gdk::pixbuf to read/write images and skip linking highgui wich is the cause of the problem.
Here is how you can convert Mat & pixbuf:
cv::Mat mat(cv::Size(pixbuf->get_width(),pixbuf->get_height()),
CV_8UC3, (uchar*)pixbuf->get_pixels(), pixbuf->get_rowstride());
RefPtr<Gdk::Pixbuf> pixbuf = Gdk::Pixbuf::create_from_data((guint8*)mat.data,
Gdk::COLORSPACE_RGB,false,8,mat.cols,mat.rows,mat.step);
The "false" parameter is for transparency.

Answer 2

It seems that OpenCV uses gtk+2. While there has been some effort to extend support to version 3, the latest on that is that the pull request has not been fully approved. Until then, one can only use gtk+2 when using OpenCV.
For those interested in supporting the effort, visit the pull request page on github.