Book Image

Kivy: Interactive Applications in Python

By : Roberto Ulloa
4 (1)
Book Image

Kivy: Interactive Applications in Python

4 (1)
By: Roberto Ulloa

Overview of this book

Mobiles and tablets have brought with them a dramatic change in the utility of applications. Compatibility has become essential, and this has increased the kind of interaction that users expect: gestures, multi-touches, animations, and magic pens. Kivy is an open source Python solution that covers these market needs with an easy-to-learn and rapid development approach. Kivy is growing fast and gaining attention as an alternative to the established developing platforms. Kivy: Interactive Applications in Python quickly introduces you to the Kivy development methodology. You will learn some examples of how to use many of the Kivy components, as well as understand how to integrate and combine them into big projects. This book serves as a reference guide and is organized in such a way that once finished, you will have already completed your first project. You will start by learning the Kivy Language for building User Interfaces (UI) and vector figures. We then proceed to the uses of Kivy events and properties to glue the UI with the application logic. You then go on to build an entire User Interface (UI) starting from a hand-made sketch. Furthermore, you will go on to understand how to use the canvas and drawing instructions to create different types of geometrical figures. Finally, you will be introduced to a big set of interactive and smooth features: transformations (scale, rotate, and translate), gestures, animations, scheduling tasks, and multi-touch elements. Kivy: Interactive Applications in Python expands your knowledge by introducing various components that improve the User Experience (UX). Towards the end of the book, you will be confident to utilize Kivy components and strategies to start any application or game you have in mind.
Table of Contents (13 chapters)
Kivy: Interactive Applications in Python
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Creating your own events – the magical properties


This section covers the use of Kivy properties. A Kivy property triggers an event every time we modify it. There are different types of properties, from the simple NumericProperty or StringProperty to much more complex versions like ListProperty, DictProperty, or ObjectProperty. For example, if we define a StringProperty, called text, then an on_text event is going to be triggered each time text is modified.

Note

The on_translation method (line 243) is associated with the ListProperty in line 216 called translation. Once we define a Kivy property, Kivy internally creates an event associated with that property. The property name is generated adding the prefi x on_ to the name of the property.

All the properties work in the same way. For example, the state property of ToogleButton is actually a property which creates the on_state event. We alreadsed this event in line 203. We define the property and Kivy creates the event for us.

Note

In the context...