How to inject an event like button press programmatically in gtkmm C++? - c++

Question

I am very new to C++ gtkmm (Linux) programming. I developing a program where I need a button to be clicked in the callback function of another button on the gui.
I have tried
button.activate()
But it only animates the button click but the callback function is not called. When I click the button manually, the callback function is called.
Please explain how to inject event into the gtkmm C++ coding. Events may include button press, key press etc.

Answer 1

Here is an example that works with Gtkmm 3.24 for a button click:
#include <iostream>
#include <gtkmm.h>
class MainWindow : public Gtk::ApplicationWindow
{
public:
MainWindow();
private:
Gtk::Grid m_layout;
Gtk::Label m_label;
Gtk::Button m_buttonA;
Gtk::Button m_buttonB;
};
MainWindow::MainWindow()
: m_buttonA{"A"}
, m_buttonB{"B"}
{
m_label.set_text("Click a button...");
m_buttonA.signal_clicked().connect(
[this](){
std::cout << "Button A clicked!" << std::endl;
// Emits "clicked" on button B, just like when
// a user clicks it:
m_buttonB.clicked();
m_buttonB.activate_action("clicked");
}
);
m_buttonB.signal_clicked().connect(
[this](){
std::cout << "Button B clicked!" << std::endl;
}
);
m_layout.attach(m_buttonA, 0, 0, 1, 1);
m_layout.attach(m_buttonB, 1, 0, 1, 1);
add(m_layout);
}
int main(int argc, char *argv[])
{
std::cout << "Gtkmm version : " << gtk_get_major_version() << "."
<< gtk_get_minor_version() << "."
<< gtk_get_micro_version() << std::endl;
auto app = Gtk::Application::create(argc, argv, "org.gtkmm.examples.base");
MainWindow window;
window.show_all();
return app->run(window);
}
With Gtkmm 4 however, the clicked() method seems to have been removed from Gtk::Button's interface. By looking at the new interface, there is a activate_action method (inherited from Gtk::Widget) that, maybe, could work. However, I don't have Gtkmm 4 here, so I could not try it.