Custom Widgets

#ifndef GTKMM_CUSTOM_WIDGET_MYWIDGET_H
#define GTKMM_CUSTOM_WIDGET_MYWIDGET_H

#include <gtkmm/widget.h>

class MyWidget : public Gtk::Widget
{
public:
  MyWidget();
  virtual ~MyWidget();

protected:

  //Overrides:
  virtual void on_size_request(Gtk::Requisition* requisition);
  virtual void on_size_allocate(Gtk::Allocation& allocation);
  virtual void on_map();
  virtual void on_unmap();
  virtual void on_realize();
  virtual void on_unrealize();
  virtual bool on_expose_event(GdkEventExpose* event);

  Glib::RefPtr<Gdk::Window> m_refGdkWindow;

  int m_scale;
};

#endif //GTKMM_CUSTOM_WIDGET_MYWIDGET_H

#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include <gtkmm.h>
#include "mywidget.h"

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

protected:
  //Signal handlers:
  void on_button_quit();

  //Child widgets:
  Gtk::VBox m_VBox;
  MyWidget m_MyWidget;
  Gtk::HButtonBox m_ButtonBox;
  Gtk::Button m_Button_Quit;
};

#endif //GTKMM_EXAMPLEWINDOW_H

#include "mywidget.h"
#include <gdkmm/drawable.h>
#include <gdkmm/general.h>  // for cairo helper functions
#include <iostream>
//#include <gtk/gtkwidget.h> //For GTK_IS_WIDGET()
#include <cstring>


MyWidget::MyWidget() :
  //The GType name will actually be gtkmm__CustomObject_mywidget
  Glib::ObjectBase("mywidget"),
  Gtk::Widget(),
  m_scale(1000)
{
  set_has_window(true);

  //This shows the GType name, which must be used in the RC file.
  std::cout << "GType name: " << G_OBJECT_TYPE_NAME(gobj()) << std::endl;

  //This show that the GType still derives from GtkWidget:
  //std::cout << "Gtype is a GtkWidget?:" << GTK_IS_WIDGET(gobj()) << std::endl;

  //Install a style so that an aspect of this widget may be themed via an RC
  //file: 
  gtk_widget_class_install_style_property(GTK_WIDGET_CLASS(
              G_OBJECT_GET_CLASS(gobj())), 
      g_param_spec_int("example_scale",
        "Scale of Example Drawing",
        "The scale to use when drawing. This is just a silly example.",
        G_MININT,
        G_MAXINT,
        0,
        G_PARAM_READABLE) );

  gtk_rc_parse("custom_gtkrc");
}

MyWidget::~MyWidget()
{
}

void MyWidget::on_size_request(Gtk::Requisition* requisition)
{
  //Initialize the output parameter:
  *requisition = Gtk::Requisition();

  //Discover the total amount of minimum space needed by this widget.

  //Let's make this simple example widget always need 50 by 50:
  requisition->height = 50;
  requisition->width = 50;
}

void MyWidget::on_size_allocate(Gtk::Allocation& allocation)
{
  //Do something with the space that we have actually been given:
  //(We will not be given heights or widths less than we have requested, though
  //we might get more)

  //Use the offered allocation for this container:
  set_allocation(allocation);

  if(m_refGdkWindow)
  {
    m_refGdkWindow->move_resize( allocation.get_x(), allocation.get_y(),
            allocation.get_width(), allocation.get_height() );
  }
}

void MyWidget::on_map()
{
  //Call base class:
  Gtk::Widget::on_map();
}

void MyWidget::on_unmap()
{
  //Call base class:
  Gtk::Widget::on_unmap();
}

void MyWidget::on_realize()
{
  //Do not call base class Gtk::Widget::on_realize().
  //It's intended only for widgets that set_has_window(false).

  set_realized();
  ensure_style();

  //Get the themed style from the RC file:
  get_style_property("example_scale", m_scale);
  std::cout << "m_scale (example_scale from the theme/rc-file) is: "
      << m_scale << std::endl; 

  if(!m_refGdkWindow)
  {
    //Create the GdkWindow:

    GdkWindowAttr attributes;
    memset(&attributes, 0, sizeof(attributes));

    Gtk::Allocation allocation = get_allocation();

    //Set initial position and size of the Gdk::Window:
    attributes.x = allocation.get_x();
    attributes.y = allocation.get_y();
    attributes.width = allocation.get_width();
    attributes.height = allocation.get_height();

    attributes.event_mask = get_events () | Gdk::EXPOSURE_MASK; 
    attributes.window_type = GDK_WINDOW_CHILD;
    attributes.wclass = GDK_INPUT_OUTPUT;

    m_refGdkWindow = Gdk::Window::create(get_parent_window(), &attributes,
            GDK_WA_X | GDK_WA_Y);
    set_window(m_refGdkWindow);

    //Attach this widget's style to its Gdk::Window.
    style_attach();

    //set colors
    modify_bg(Gtk::STATE_NORMAL , Gdk::Color("red"));
    modify_fg(Gtk::STATE_NORMAL , Gdk::Color("blue"));

    //make the widget receive expose events
    m_refGdkWindow->set_user_data(gobj());
  }
}

void MyWidget::on_unrealize()
{
  m_refGdkWindow.reset();

  //Call base class:
  Gtk::Widget::on_unrealize();
}

bool MyWidget::on_expose_event(GdkEventExpose* event)
{
  if(m_refGdkWindow)
  {
    double scale_x = (double)get_allocation().get_width() / m_scale;
    double scale_y = (double)get_allocation().get_height() / m_scale;

    Cairo::RefPtr<Cairo::Context> cr = m_refGdkWindow->create_cairo_context();
    if(event)
    {
      // clip to the area that needs to be re-exposed so we don't draw any
      // more than we need to.
      cr->rectangle(event->area.x, event->area.y,
              event->area.width, event->area.height);
      cr->clip();
    }

    // paint the background
    Gdk::Cairo::set_source_color(cr, get_style()->get_bg(Gtk::STATE_NORMAL));
    cr->paint();

    // draw the foreground
    Gdk::Cairo::set_source_color(cr, get_style()->get_fg(Gtk::STATE_NORMAL));
    cr->move_to(155.*scale_x, 165.*scale_y);
    cr->line_to(155.*scale_x, 838.*scale_y);
    cr->line_to(265.*scale_x, 900.*scale_y);
    cr->line_to(849.*scale_x, 564.*scale_y);
    cr->line_to(849.*scale_x, 438.*scale_y);
    cr->line_to(265.*scale_x, 100.*scale_y);
    cr->line_to(155.*scale_x, 165.*scale_y);
    cr->move_to(265.*scale_x, 100.*scale_y);
    cr->line_to(265.*scale_x, 652.*scale_y);
    cr->line_to(526.*scale_x, 502.*scale_y);
    cr->move_to(369.*scale_x, 411.*scale_y);
    cr->line_to(633.*scale_x, 564.*scale_y);
    cr->move_to(369.*scale_x, 286.*scale_y);
    cr->line_to(369.*scale_x, 592.*scale_y);
    cr->move_to(369.*scale_x, 286.*scale_y);
    cr->line_to(849.*scale_x, 564.*scale_y);
    cr->move_to(633.*scale_x, 564.*scale_y);
    cr->line_to(155.*scale_x, 838.*scale_y);
    cr->stroke();
  }
  return true;
}

#include "examplewindow.h"

ExampleWindow::ExampleWindow()
: m_Button_Quit("Quit")
{
  set_title("Custom Widget example");
  set_border_width(6);
  set_default_size(400, 200);

  add(m_VBox);
  m_VBox.pack_start(m_MyWidget, Gtk::PACK_EXPAND_WIDGET);
  m_MyWidget.show();

  m_VBox.pack_start(m_ButtonBox, Gtk::PACK_SHRINK);

  m_ButtonBox.pack_start(m_Button_Quit, Gtk::PACK_SHRINK);
  m_ButtonBox.set_border_width(6);
  m_ButtonBox.set_layout(Gtk::BUTTONBOX_END);
  m_Button_Quit.signal_clicked().connect( sigc::mem_fun(*this, &ExampleWindow::on_button_quit) );

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

void ExampleWindow::on_button_quit()
{
  hide();
}

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

int main(int argc, char *argv[])
{
  Gtk::Main kit(argc, argv);

  ExampleWindow window;
  //Shows the window and returns when it is closed.
  Gtk::Main::run(window);

  return 0;
}