Ahmed Fawzy Mohamed Gad - Building Android Apps in Python Using Kivy with Android Studio: With Pyjnius, Plyer, and Buildozer

Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the books product page, located at www.apress.com/978-1-4842-5030-3 . For more detailed information, please visit http://www.apress.com/source-code .

Python is a popular programming language that grabs the attention of its users because its so simple and powerful. A complex task is accomplished in Python using a few lines of code. Python has a number of libraries, such as NumPy, that make life easier. Python is an essential requirement for data scientists.

Once you build a Python desktop app, its a good idea to think about distributing it to different platforms. The good news is that there is a Python framework called Kivy ( https://github.com//kivy/kivy ) for building cross-platform apps with natural user interfaces. Using the same code unchanged, you can produce apps for the Windows, Linux, Mac, iOS, and Android platforms. This book focuses on building Android apps and exploiting the Android features using Kivy. Multiple user interface elements (widgets) are introduced throughout the book.

The framework is very easy to learn once you understand the basic app structure. Because Kivy is simple, the challenge is not learning the Kivy features but using them effectively to build rich apps. This book provides a good recipe for building a number of apps that effectively use Kivy features. Lets look at an overview of the book chapters.

Chapter introduces Kivy and prepares its development environment in a Linux platform for building Kivy desktop apps. Throughout the book, a desktop Kivy app is created first to check whether everything is working as expected. After that, this chapter produces Android apps. Buildozer and Python-4-Android are the two projects used to produce the Android app. This is by building an Android Studio project based on the Kivy project. The structure of the Android Studio project maps between the Kivy app and the Android app. Once the Android Studio project is created successfully, the APK file of the app can be installed on Android devices. Moreover, the app can be published at Google Play, similar to regular Android apps.

Chapter introduces the KV language for placing the widget tree of the Kivy app in a different file than the Python file. This makes debugging the app much easier.

Chapter discusses the Camera widget, which enables you to access the Android camera very easily. Kivy canvases are discussed for drawing on the Kivy widgets and applying transformations. The captured images are uploaded to a Flask HTTP server to display them in a Web browser.

Chapter uses the Screen widget for separating the widgets across multiple screens, where each screen has a task to do. Navigation from one screen to another is discussed.

Chapters build a multi-level game from scratch in which a player has a mission of collecting a number of uniformly distributed coins on the screen. Monsters and fires kill the player if a collision occurs.

Chapter is a complete guide for understanding how to edit the Android Studio project produced from the Kivy app within Android Studio. After the project is exported using Buildozer, it is imported in Android Studio as a regular Android app. By doing this, you can add whatever functionality you want to the Android app. If the functionality is not available within the Kivy app, you can add it within Android Studio. This chapter discusses how to access the Kivy widgets within Android Studio to handle their actions. The loading screen of the Kivy app is edited. Moreover, OpenCV is imported into the project and an image is loaded and processed once a Kivy button is pressed.

Thanks to Allah who planted the idea of starting this book in my mind. Writing a book is not easy but Allah helps me meet the challenges. I always remember Ayah 15 from Surah Al-Naml in the Nobel Quran: And We had certainly given to David and Solomon knowledge, and they said, Praise [is due] to Allah, who has favored us over many of His believing servants.

Thanks to the Apress team, including Celestin John, Divya Modi, Welmoed Spahr, and Rita Fernando. This is my second time working with them and I happy to repeat the experience.

I am grateful to the Kivy community, led by Mathieu Virbel and Gabriel Pettier, who did a good job building such a wonderful open source framework. It makes it easier to build cross-platform apps in Python. I implore companies to fund this awesome project.

Thanks to Matthew Mayo, a researcher and editor at KDnuggets, for sharing my tutorials with readers all over the world. Thanks to Austin Kodra, head of the Fritz community, for his trust and for making me part of Heartbeat and sharing my writings.

Thanks to my colleague, Mohamed Hamed, a teaching assistant and a senior Android app developer, for giving me Android Studio packaged with the necessary tools to start app development.

I am grateful to Dr. Mahmoud Albawaneh, Executive Director of Institutional Research and Analytics at California State University, Long Beach, for helping me get out of my comfort zone and for always helping me.

I am delighted to say thanks to my friend Fatima Ezzahra Jarmouni, a Moroccan data scientist, for the continuous encouragement and for never letting me walk alone.

I am very thankful to Monica Abdullah Yunis, a kind Palestine-American Muslim mother, for teaching me perseverance through fasting in order to cleanse my soul and mind just for Allah. This is a cure for depression. She is always a wise supporter of me and available to help me.