Scrollable DrawingArea?

["Johan Winge" <johan winge telia com>]

I have problems understanding how I can get a DrawingArea scrollable. I  
have written a small program which loads an image and shows it in a  
DrawingArea, placed inside a ScrolledWindow. This works great, except for  
the scrollbars, which are unusable. Am I supposed to update them manually,  
and how in that case? Or is there another way to do what I want to achieve  
(load a picture, display it with scrollbars, and also analyse and modify  
individual pixels.)

Just for your information, I'm a newbie when it comes to gtkmm, nor am I  
that familiar with the C++ language. I'm learning by doing.

This is the complete program (the file "test.tiff" is a relatively large  
image):



#include <gtkmm.h>

class MyArea : public Gtk::DrawingArea
{
public:

  MyArea()
  {
    image = Gdk::Pixbuf::create_from_file("test.tiff");
  }
  virtual ~MyArea();

protected:

  Glib::RefPtr<Gdk::Pixbuf> image;

  bool on_expose_event(GdkEventExpose* event)
  {
    Glib::RefPtr<Gdk::Window> window = get_window();
    if(window && image)
    {
       image->render_to_drawable(window, get_style()->get_black_gc(),
         0, 0, 0, 0, image->get_width(), image->get_height(),  
Gdk::RGB_DITHER_NONE, 0, 0);
    }

    return true;
  }

};

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

  Gtk::ScrolledWindow scrolledwindow;
  window.add(scrolledwindow);

  MyArea drawingarea;
  scrolledwindow.add(drawingarea);

  window.show_all_children();

  Gtk::Main::run(window);
  return 0;
}




Thanks,
Johan Winge