Compounding properties

While working with properties in Kivy, there are times when we will have to create our own property that usually is a compound of some standard properties.

Getting ready

Again, for this recipe, it is important to understand the properties in Kivy that have been reviewed in Chapter 1, Kivy and the Kv language, articular in the Declaring properties within a class recipe. We will be learning in detail about AliasProperty, in which you need to create a custom getter and setter methods that fit your needs.

How to do it…

For this recipe, follow these steps:

1. Define a getter method in your code.

2. Define the setter method.

3. Create the reference for AliasProperty.

4. Define the method to fire the event:

   def get_right(self):
       return self.x + self.width
   
   def set_right(self, value):
       self.x = value - self.width
   
   right = AliasProperty(get_right, set_right, bind=('x', 'width'))
       def on_right():
           print "Hello"

How it works…

The first line defines the getter method, which will get...