[Matplotlib-users] Get the gtk.DrawingArea

[Luigi P. <lu...@la...>]

Hi!

I'm trying to create a customized cursor crosshair in my plot. It is 
inserted into a gtk.Window. I'm using GTKAGG backend.

In order do this, I need to create a class CursorCrosshair for a code 
like this:

** CODE **

   win = gtk.Window()
   win.connect("destroy", lambda x: gtk.main_quit())
   win.set_default_size(400,300)

   figure = Figure()

   t = arange(0.0, 1.0, 0.01)
   s = sin(2*2*pi*t)

   sub1 = figure.add_subplot(111)
   sub1.plot(t, s, 'o')

   box = gtk.VBox()

   canvas = FigureCanvasGTKAgg(figure)
   cursor = CursorCrosshair()
   connect('motion_notify_event', cursor.draw_cursor)

   toolbar = NavigationToolbar2GTK( canvas, win )
   toolbar.update()

   box.pack_start(canvas, True, True)
   box.pack_end(toolbar, False, False)

   win.add(box)

   win.show_all()
   gtk.main()

*********


Into the draw_cursor method of CursorCrosshair class I'll paint the 
horizontal and vertical lines.

Well, the canvas in my example (FigureCanvasGTKAgg) inherits from 
gtk.DrawingArea, that is the GTK "real" canvas I need to paint into 
CursorCrosshair.draw_cursor(...) method.  gtk.DrawingArea has a method 
named draw_line(gc, x1, y1, x2, y2) that needs the coordinates and a 
graphics context as input parameters.

OK: how can I get the graphics context? What is it? And can I really use 
FigureCanvasGTKAgg like a gtk.DrawingArea object? If I cannot, how can I 
draw a line directly on the gtk inner canvas class (gtk.DrawingArea).

Thanks in advance.

Luigi