[Glade-users] adding custom widgets written with Gtkmm

[tristan at wibberley.org (Tristan Wibberley)]

Hi

I've made a widget in a custom widget library (I think that's what I've
managed). The so is built with one source file (as below) from a gtkmm
tutorial and I've added the lines in the extern "C" section. This seems
like it should be correct.

Then I wrote a catalog xml file below which I copied
to /usr/share/glade3/catalogs and I copied the library libcustom.so
to /usr/lib/glad3/modules.

glade-3 doesn't load my widget into the toolbox and says:

====================================================
GladeUI-Message: 1 missing displayable value for
GnomeDateEdit::dateedit-flags

(glade-3:10870): GladeUI-CRITICAL **: Unable to load module 'custom'
from any search paths

(glade-3:10870): GladeUI-WARNING **: Failed to load external library
'custom'

(glade-3:10870): GladeUI-WARNING **: We could not find the symbol
"mywidget_get_type"

(glade-3:10870): GladeUI-WARNING **: Could not get the type from
"Mywidget"

(glade-3:10870): GladeUI-WARNING **: Failed to load the GType for
'Mywidget'

(glade-3:10870): GladeUI-WARNING **: Tried to include undefined widget
class 'Mywidget' in a widget group
====================================================

catalog file
====================================================
<glade-catalog name="custom" library="custom" requires="gtk+">

  <glade-widget-classes>
    <glade-widget-class name="Mywidget" generic-name="mywidget"
title="Frobnicator"/>
  </glade-widget-classes>

  <glade-widget-group name="foo" title="Foo">
    <glade-widget-class-ref name="Mywidget"/>
  </glade-widget-group>

</glade-catalog>
====================================================

libcustom.so source file
====================================================
#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;
};

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

extern "C" {
  GType mywidget_get_type (void) {
    return MyWidget::get_type();
  }
  GtkWidget *
  mywidget_new (void)
  {
    return manage(new MyWidget())->gobj();
  }
}

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

  //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()
{
  //Call base class:
  Gtk::Widget::on_realize();

  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 = {0};
  
    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_window() /* parent */,
&attributes,
            GDK_WA_X | GDK_WA_Y);
    unset_flags(Gtk::NO_WINDOW);
    set_window(m_refGdkWindow);

    //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.clear();

  //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;
}

-- 
Tristan Wibberley