#  HelloGTK.py   (c) Kari Laitinen

#  http://www.naturalprogramming.com

#  2006-10-05  First program version created.
#  2006-10-05  Last modification.

#  This program draws two lines of text onto the screen.

#  drawing_area_exposed() is the 'paint' method of this application.
#  It will be called automatically whenever there is a need to
#  redraw the contents of the window.

#  A gtk.DrawingArea object is a 'canvas' on which it is possible
#  to draw various objects, such as lines of text. A DrawingArea is
#  created in this program, and it is added to a window with the add()
#  method.

#  By using a method named connect(), the method that updates the
#  screen, i.e. the drawing_area_exposed() method, is set to handle
#  a signal named "expose-event". This signal is received whenever
#  the drawing area is exposed, i.e., whenever it is necessary to
#  to update the drawing area.

#  In this program text_to_show refers to a pango.Layout object
#  which represents a paragraph of text. With the set_text() method
#  the actual text inside the object can be set.

import gtk

class HelloApplication :

   def __init__( self ) :

      self.application_window = gtk.Window( gtk.WINDOW_TOPLEVEL )
      self.application_window.connect( "destroy", gtk.main_quit )
      self.application_window.set_size_request( 400, 250 )
      
      self.drawing_area = gtk.DrawingArea()

      self.drawing_area.connect( "expose-event", self.drawing_area_exposed )

      self.application_window.add( self.drawing_area )

      self.application_window.show_all()

   def drawing_area_exposed( self, area, event ) :

      graphics_context = self.drawing_area.get_style().fg_gc[gtk.STATE_NORMAL]
      this_drawable  =  self.drawing_area.window
      text_to_show   =  self.drawing_area.create_pango_layout("")

      text_to_show.set_text( "Hello. I am a Python/GTK/Linux application." )
      this_drawable.draw_layout( graphics_context, 80, 100, text_to_show )

      text_to_show.set_text( "The coordinates of this line are (80,150)." )
      this_drawable.draw_layout( graphics_context, 80, 150, text_to_show )

      return True

   def run( self ) :

      gtk.main()

if __name__ == "__main__" :

      this_application  =  HelloApplication()
      this_application.run()