Using opencv and gtk+2 together - c++

Question

so i am currently trying to achieve the following: Create a gui for the user were the user can see a livefeed of the webcam and also have two buttons left of the livefeed to start and stop the recording. all this has to run on a raspberry pi.
I am using a basler camera so i can not use the videocapture object but using the pylon sdk (sdk for basler cameras) i managed to grab an image and convert it into a opencv::mat.
however im stuck on two points:
first i do not know how to display an opencv::mat on a gtk widget at all.
the second problem is that i do not know how to get a live stream. I tried to use the g_timeout_add function but then the ui gets unresponsive. it calls the function in background but since i call it every 100ms it seems to be stuck forever in the function and therefore i can not click on any buttons.
i have included some of my code below.
#include <gtk/gtk.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/video/video.hpp>
#include <pylon/PylonIncludes.h>
using namespace Pylon;
using namespace cv;
using namespace std;
void callback(GtkWidget *widget, gpointer labelstatus) {}
gint delete_event(GtkWidget *widget, GdkEvent *event) {
gtk_main_quit ();
}
static gboolean livefeed_func(gpointer data) {
Pylon::PylonAutoInitTerm autoInitTerm;
CInstantCamera camera(CTlFactory::GetInstance().CreateFirstDevice());
camera.Open();
GenApi::INodeMap& nodemap = camera.GetNodeMap();
.
. Some other pylon related stuff
.
CImageFormatConverter formatConverter;
formatConverter.OutputPixelFormat= PixelType_BGR8packed;
CPylonImage pylonImage;
Mat openCvImage;
cv::Size frameSize = Size((int)width->GetValue(), (int)height->GetValue());
.
. Some other pylon related stuff
.
formatConverter.Convert(pylonImage, ptrGrabResult);
openCvImage = cv::Mat(ptrGrabResult->GetHeight(), ptrGrabResult->GetWidth(), CV_8UC3, (uint8_t *) pylonImage.GetBuffer());
imwrite("tmp_name.jpg", openCvImage);
}
int main(int argc, char *argv[]) {
//GTK
GtkWidget *window;
GtkWidget *table;
GtkWidget *labelstatus;
GtkWidget *labellog;
GtkWidget *buttonexit;
GtkWidget *buttonstart;
GtkWidget *buttonstop;
GtkWidget *livefeed;
gtk_init (&argc, &argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_title (GTK_WINDOW (window), "Table");
gtk_container_set_border_width (GTK_CONTAINER (window), 20);
gtk_signal_connect (GTK_OBJECT (window), "delete_event", GTK_SIGNAL_FUNC (delete_event), NULL);
table = gtk_table_new (6, 6, TRUE);
gtk_container_add (GTK_CONTAINER (window), table);
labelstatus = gtk_label_new ("Status: Idle");
gtk_table_attach_defaults (GTK_TABLE(table), labelstatus, 0, 2, 0, 1);
gtk_widget_show (labelstatus);
buttonstart = gtk_button_new_with_label ("Start");
gtk_signal_connect (GTK_OBJECT (buttonstart), "clicked", GTK_SIGNAL_FUNC (callback), (gpointer) labelstatus);
gtk_table_attach_defaults (GTK_TABLE(table), buttonstart, 0, 1, 1, 2);
gtk_widget_show (buttonstart);
buttonstop = gtk_button_new_with_label ("Stop");
gtk_signal_connect (GTK_OBJECT (buttonstop), "clicked", GTK_SIGNAL_FUNC (callback), NULL);
gtk_table_attach_defaults (GTK_TABLE(table), buttonstop, 1, 2, 1, 2);
gtk_widget_show (buttonstop);
labellog = gtk_label_new ("11:31:54: Started Recording\n11:36:54: Stopped Recording");
gtk_table_attach_defaults (GTK_TABLE(table), labellog, 0, 2, 2, 3);
gtk_widget_show (labellog);
buttonexit = gtk_button_new_with_label ("Quit");
gtk_signal_connect (GTK_OBJECT (buttonexit), "clicked",GTK_SIGNAL_FUNC (delete_event), NULL);
gtk_table_attach_defaults (GTK_TABLE(table), buttonexit, 0, 2, 3, 4);
gtk_widget_show (buttonexit);
livefeed = gtk_drawing_area_new();
gtk_table_attach_defaults (GTK_TABLE(table), livefeed, 2, 5, 0, 4);
gtk_widget_show (livefeed);
gtk_widget_show (table);
gtk_widget_show (window);
g_timeout_add(100, livefeed_func, livefeed);
gtk_main ();
}
so if i run this code it will display the gtk window and then be unresponsive and write images until i cancel the process.
So to sum it up:
is there a way to execute background tasks in gtk without the ui becoming unresponsive
how can i display an opencv::Mat in a gtk window/widget?