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

Localizing coordinates – adding stickmen


In the last section, we used the to_parent() method (line 66) to translate the coordinates relative to the DrawingSpace to its parent.

Note

Please note, that we were inside DraggableWidget and the coordinates we received were relative to the parent (DrawingSpace).

These coordinates are convenient for DraggableWidget because we position it in the parent's coordinates. It allows us to use the coordinates in the parent's collide_point. This is no longer convenient when we want to check the coordinates on the parent's parent space or when we need to draw something directly on the canvas of a Widget.

Before studying more examples, let's summarize the theory.You learned that RelativeLayout is very useful because it is easier to think inside of a constraint space to localize our objects. The problems start when we need to translate the coordinates to other Widget area. Let us consider the following screenshot of a Kivy program:

Three Embedded Relative Layouts...