Source Code

File: examplewindow.h (For use with gtkmm 3, not gtkmm 2)

#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include <gtkmm.h>

class ExampleWindow : public Gtk::Window
{
public:
  ExampleWindow();
  virtual ~ExampleWindow();

protected:
  //Signal handlers:
  void on_color_button_color_set();
  void on_button_dialog_clicked();
  bool on_drawing_area_draw(const Cairo::RefPtr<Cairo::Context>& cr);

  //Child widgets:
  Gtk::Box m_VBox;
  Gtk::ColorButton m_ColorButton;
  Gtk::Button m_Button_Dialog;
  Gtk::DrawingArea m_DrawingArea; //To show the color.

  Gdk::RGBA m_Color;
};

#endif //GTKMM_EXAMPLEWINDOW_H

File: main.cc (For use with gtkmm 3, not gtkmm 2)

#include "examplewindow.h"
#include <gtkmm/application.h>

int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create(argc, argv, "org.gtkmm.example");

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app->run(window);
}

File: examplewindow.cc (For use with gtkmm 3, not gtkmm 2)

#include "examplewindow.h"
#include <iostream>

ExampleWindow::ExampleWindow()
: m_VBox(Gtk::ORIENTATION_VERTICAL, 5),
  m_Button_Dialog("Choose Color")
{
  set_title("Gtk::ColorChooserDialog example");
  set_default_size(200, 200);

  add(m_VBox);

  m_VBox.pack_start(m_ColorButton, Gtk::PACK_SHRINK);
  m_ColorButton.signal_color_set().connect(sigc::mem_fun(*this,
    &ExampleWindow::on_color_button_color_set) );

  m_VBox.pack_start(m_Button_Dialog, Gtk::PACK_SHRINK);
  m_Button_Dialog.signal_clicked().connect(sigc::mem_fun(*this,
    &ExampleWindow::on_button_dialog_clicked) );

  //Set start color:
  m_Color.set_red(0.0);
  m_Color.set_green(0.0);
  m_Color.set_blue(1.0);
  m_Color.set_alpha(1.0); //opaque
  m_ColorButton.set_rgba(m_Color);

  m_VBox.pack_start(m_DrawingArea);
  m_DrawingArea.signal_draw().connect(sigc::mem_fun(*this,
    &ExampleWindow::on_drawing_area_draw));

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

void ExampleWindow::on_color_button_color_set()
{
  //Store the chosen color:
  m_Color = m_ColorButton.get_rgba();
}

void ExampleWindow::on_button_dialog_clicked()
{
  Gtk::ColorChooserDialog dialog("Please choose a color");
  dialog.set_transient_for(*this);

  //Get the previously selected color:
  dialog.set_rgba(m_Color);

  const int result = dialog.run();

  //Handle the response:
  switch(result)
  {
    case Gtk::RESPONSE_OK:
    {
      //Store the chosen color:
      m_Color = dialog.get_rgba();
      m_ColorButton.set_rgba(m_Color);
      break;
    }
    case Gtk::RESPONSE_CANCEL:
    {
      std::cout << "Cancel clicked." << std::endl;
      break;
    }
    default:
    {
      std::cout << "Unexpected button clicked: " << result << std::endl;
      break;
    }
  }
}

bool ExampleWindow::on_drawing_area_draw(const Cairo::RefPtr<Cairo::Context>& cr)
{
  Gdk::Cairo::set_source_rgba(cr, m_Color);
  cr->paint();

  return true;
}