Creating Apps in Kivy (2014)

Preface

This book introduces Kivy, an exciting new graphical user interface library that finally allows Python to be used to code cross-platform applications on most traditional and mobile operating systems. I’m happy you’re here to study Kivy with me and hope that you’ll enjoy reading it as much as I have enjoyed writing it. I am confident that you will be happy with the App you develop and deploy in this book and that it will lead you to develop many new applications of your own design. I look forward to seeing your Kivy Apps on the Android and iTunes market in the near future!

Who Should Read This Book

This book is primarily targeted to fairly new programmers who have read the Python tutorial, but haven’t done a lot of real-world coding. In addition to instructing you in Kivy, this book introduces you to the programming workflow. Each chapter builds on the previous chapter to help you create a fully functional mobile application. You will learn the steps you need to follow to design and implement your own apps.

It will also be applicable to programmers who have not worked with Python before but want to use Kivy for its amazing API, integrated multitouch support, or cross-platform deployment. You will probably want to review the Python tutorial to get a leg up on the language’s syntax before reading this book. You may be able to skim some sections of the text if you already understand the culture of coding.

Technology Used in This Book

The examples in this book all target Python 3. All but three of them also run seamlessly on Python 2.7. Those three examples have been highlighted in sidebars that include simple workarounds you can use to make the code run on both Python 2.7 and Python 3. Then, any future examples that use the same code will always use the version that works on both Pythons.

I encourage you to use Python 3 if possible, as it is a more enjoyable language to work with, provides nicer APIs, and is slowly being adopted by the entire Python community. That said, depending on what operating system you use, Python 2 may be easier to deploy and develop against at this time. You will have no trouble using Python 2.7 with the examples in this book if you prefer it.

This book was written entirely against Kivy 1.8, which is the first version of Kivy to support Python 3. The examples have been tested somewhat against Kivy 1.7, and it works with all the chapters except Chapter 6. Please use Kivy 1.8 or later if you can. The Kivy developers move very fast, and the newest version is always far better than the previous one in all dimensions: speed, stability, and features.

Conventions Used in This Book

The following typographical conventions are used in this book:

Italic

Indicates new terms, URLs, email addresses, filenames, and file extensions.

Constant width

Used for program listings, as well as within paragraphs to refer to program elements such as variable or function names, databases, data types, environment variables, statements, and keywords. Also used for commands and command-line options.

Constant width bold

Shows commands or other text that should be typed literally by the user.

Constant width italic

Shows text that should be replaced with user-supplied values or by values determined by context.

TIP

This element signifies a tip or suggestion.

NOTE

This element signifies a general note.

WARNING

This element indicates a warning or caution.