Kivy and properties

Even though we have only touched on explanations of properties in the section, the truth is that we have been using them since the beginning of this chapter.Kivy's internals are full of properties. They are almost everywhere. For example, when we implemented DraggableWidget, we simply modified theroperty center_x and center_y (line 72) and the whole Widget was updated because there are properties involved in the use of center_x.

The last example in this chapter illustrates how powerful the Kivy properties are. Here is the code for statusbar.py:

270. # File name: statusbar.py
271. from kivy.uix.boxlayout import BoxLayout
272. from kivy.properties import NumericProperty, ObjectProperty
273. 
274. class StatusBar(BoxLayout):
275.     counter = NumericProperty(0)
276.     previous_counter = 0
277. 
278.     def on_counter(self, instance, value):
279.         if value == 0:
280.             self.msg_text = "Drawing space cleared"
281.         elif value - 1 == self.__class__...