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Google Summer of Code - 2015


Kivy is a cross-platform, business friendly, GPU Accelerated open source Python library for rapid development of applications that make use of innovative user interfaces, such as multi-touch apps.

The Kivy Organization oversees several major projects:

  • The Kivy GUI Library
  • The Python-For-Android compilation tool.
  • The Kivy-iOS compilation tool.
  • The PyJNIus library for interfacing with Java from Python.
  • The PyOBJus library for interfacing with Objective-C from Python.
  • The Plyer platform-independent Python wrapper for platform dependent APIs.
  • Buildozer - A generic Python packager for Android, iOS, and desktop.

Altogether, these projects allow the user to create applications for every major operating system that make use of any native APIs present. Our goal is to enable development of Python applications that run everywhere off the same codebase and make use of platform dependent APIs and features that users of specific operating systems have come to expect.

Depending on which project you choose you may need to know Cython, OpenGL ES2, Java, Objective-C, or C in addition to python. We make heavy use of Cython and OpenGL for computational and graphics performance where it matters, and the other languages are typically involved in accesses OS or provider level APIs.

We are hoping to participate in Google Summer of Code 2015. This page showcases some ideas for GSoC projects and corresponding guidelines for students contributing to the Kivy Framework.


It is assumed that the incoming student meets some basic requirements as highlighted here:

  • Intermediate level familiarity with Python.
  • Comfortable with git and github (Kivy and its sister projects are all managed on github) If you have never used github before you may be interested in this tutorial.
  • Comfortable with event driven programming.
  • Has suitable tools/environment for kivy or the sister project you are going to work on. For example to be able to work on PyOBJus you would need access to an iOS device, mac with xcode and a developer license, to work on PyJNIus you would need an Android device, and to work on plyer you would need access to hardware for both platforms.

Additional desired skills may be listed with specific projects.

Familiarize yourself with the contributing guide We can help you get up to speed, however students demonstrating ability in advance will be given preference.

How to get setup

For Kivy, the easiest way is to follow the installation instructions for the development version for your specific platform:


For the rest it’s usually sufficient to install the relevant project from git and add it to your PYTHONPATH.

eg.. for PyJNIus:

git clone http://github.com/kivy/pyjnius
export PYTHONPATH=/path/to/pyjnius:$PYTHONPATH

Project Ideas

Here are some prospective ideas sourced from the Kivy development team, if none of these projects interest you come talk to us in #kivy-dev about a project idea of your own.

Beginner Projects

These projects should be suitable for anyone with a college level familiarity with Python and require little knowedge of platform specifics.

Kivy Designer

Kivy Designer is a GUI tool for creating Kivy GUI layouts written in Kivy. You can compose, customize, and test widgets using the tool. This project has been the subject of 2 previous GSoC and is experimental, alpha level software at the moment. However, it is a very popular request for more updates among our users; if you are interested in GUI tool development this could be a great fit for you!

The Student will:

  • Integrate Buildozer, which is our build tool for deploying to different target OS, within the kivy-designer.
  • Interface for using hanga.io (Remote Buildozer server) as a deployment target.
  • Better File management for project files. Browser Pane.
  • Interface to test using different screen modules, for emulating interface on different screen sizes.
  • Interface to Select different targets, simulator or actual device if connected to deploy to.
  • Add mobile specific UI fixes(mostly making sure UI looks and feels the same on tablets as on desktops)
  • Work on stability fixes.
Expected outcome:
It is expected that the student completes all the features mentioned above, except stability fixes which is dependent on however much time is left after completing the rest of the features.
  • Mentors: Akshay Arora, Ryan Pessa
  • Requirements: Access to Linux, Windows, or OS X
  • Task level: Easy
  • Desired Skills: Experience with other GUI creation tools. Familiar with Kivy approach to EventLoop and UIX Widgets.

Matplotlib Integration

More advanced graphing and plotting tools are a frequently requested addition to Kivy, and it would be ideal to provide them via integration with matplotlib’s extensive feature set. The primary goal of the project would be to write a Kivy backend to matplotlib that displays plots using Kivy’s own graphics API, but it would also potentially involve ensuring that matplotlib is deployable on every platform Kivy supports.
Expected outcome:
The matplotlib widgets will be included in the Kivy garden and ready to use on all of Kivy’s supported OS.
  • Mentors: Alexander Taylor, Matthew Einhorn, Jacob Kovac
  • Requirements: Access to Desktop OS and ideally at least one mobile platform
  • Task level: Easy
  • Desired Skills: Familiarity with Kivy widget construction and matplotlib.

Intermediate Projects

These projects will involve more than just pure Python coding. You may find yourself either dealing with the details of cross platform compilation or working with communicating between Python and an API in a different language.



Plyer is a platform-independant Python API to use features commonly found on the desktop and mobile platforms supported by Kivy. The idea is to provide a stable API to the user for accessing features of their desktop or mobile device.

The student would replace some .java code currently in the Kivy project to a more appropriate place in Plyer. In addition, the student would work on improving access to platform specific features through Plyer, including accessibility, Bluetooth, Bluetooth Low Energy, recording and previewing the video camera, accessing contacts, recording audio, and utilizing speech recognition.

Under the hood you’ll use PyJNIus on Android, PyOBJus on OS X and iOS, ctypes on Windows, and native APIs on Linux. This probably would also include improving PyObjus and PyJNIus to handle interfaces that they can’t right now.

Expected outcome:
A successful outcome would include moving the Kivy Java code to plyer and implementation of some or all of the new facades to be decided with the student.
  • Mentors: Gabriel Pettier, Sebastian Popute
  • Requirements: Access to Linux, Windows, OS X, iOS device, Android device.
  • Task level: Intermediate
  • Desired Skills: Familiarity with Pyjnius, PyOBJus.

Font Reshaping and Font Fallback Support


Currently Kivy does not support reshaping for alphabets such as Arabic, Persian, Thai, or Devanagari. The solution is to integrate a text shaping engine- Harfbuzz. You would need to ensure that we can compile Harfbuzz on every platform and properly integrate it as a core text provider.

The second part of the same project would involve font fallback support. If a particular character/glyph is missing; currently we show a [] box. The solution for this would involve either using an OS API if available or maintaining a hashtable for the default fonts on each OS which can be used for glyph fallback.

Expected outcome:
Font fallback and text reshaping support Kivy and correct compilation recipes for the libs used (harfbuzz) for platforms that need it, such as Python-For-Android.
  • Mentors: Akshay Arora, Jacob Kovac
  • Requirements: Access to Desktop OS and ideally at least one mobile platform
  • Task level: Intermediate
  • Desired Skills: Familiarity with text rendering, HarfBuzz, and Kivy’s provider abstraction.

Hard Projects

These projects may involve very in-depth knowledge of Kivy’s existing internals, the hairy details of cross-platform compilation, or other fairly advanced topics. If you are comfortable with the internals of Python, working with C code, and using Cython to build your own C extensions these projects may appeal to you.

Python-For-Android Revamp:

Currently Python-For-Android is not very flexible and have a very specific bootstrap crafted for use with Kivy’s old SDL1.2/1.3 backend used through Pygame and functions only with Python2. Your job would be to make the necessary changes to expose swappable bootstraps, python interpreters, and the appropriate compilation options for ARM and x86 Android. This project will involve a significant amount of refactoring the current tool, as much hardcoded functionality needs to be made optional. A student looking to take on this task should be familiar with compiling Python, the compilation process for Cython modules, and the Android SDK and NDK.

The Student will:

  • Introduce bootstrap argument for the distribute script
  • Introduce a new SDL2 bootstrap
  • Refactor old bootstrap to use new approach
  • Refactor pyjnius to find the appropriate Activity from the provided bootstrap
  • Introduce option for compilation with Python3 instead of Python2, this will involve properly configuring the blacklist of ommitted modules, the collection of libs into one large one to avoid shared library limit on older devices, and performing any Python3 code conversions necessary.
  • Ensure all recipes work with Python3 version of their modules
  • Introduce option for compiling for different architectures (ARM and x86)
Expected outcome:
Python-for-Android with more options for compilation including Python2 and Python3, legacy Pygame bootstrap, SDL2 bootstrap, and ARM and x86 compilation options.
  • Mentors: Mathieu Virbel, Jacob Kovac
  • Requirements: Access to Linux, Android.
  • Task level: Hard
  • Desired Skills: Understanding of cross-compilation for Android, familiarity with PyJNIus

How to Contact devs

Ask your questions on the Kivy users forums http://kivy.org/#forum

Or send a mail at kivy-users@googlegroups.com

Make sure to Join kivy-dev user group too @ https://groups.google.com/forum/#!forum/kivy-dev

You can also try to contact us on IRC (online chat), to get the irc handles of the devs mentioned above visit http://kivy.org/#aboutus

Make sure to read the IRC rules before connecting. Connect to webchat

Most of our developers are located in Europe, India, and North America so keep in mind typical waking hours for these areas.

How to be a good student

If you want to participate as a student and want to maximize your chances of being accepted, start talking to us today and try fixing some smaller problems to get used to our workflow. If we know you can work well with us, you will have much better chances of being selected.

Here’s a checklist:

  • Make sure to read through the website and at least skim the documentation.
  • Look at the source code.
  • Read our contribution guidelines.
  • Make a contribution! Kivy would like to see how you engage with the development process. Take a look at the issue tracker for a Kivy project that interest you and submit a Pull Request. It can be a simple bug or a documentation change. We are looking to get a feel for how you work, not evaluating your capabilities. Don’t worry about trying to pick something to impress us.
  • Pick an idea that you think is interesting from the ideas list or come up with your own idea.
  • Do some research yourself. GSoC is about give and take, not just one sided interaction. It is about you trying to achieve agreed upon goals with our support. The main driving force in this should be, obviously, yourself. Many students pop up and ask what they should do. You shoud base that decision on your interests and your skills. Show us you’re serious about it and take the initiative.
  • Write a draft proposal about what you want to do. Include what you understand the current state of the project to be, what you would like to improve, how, etc.
  • Discuss that proposal with us in a timely manner. Get feedback.
  • Be patient! Especially on IRC. We will try to get to you if we’re available. If not, send an email and just wait. Most questions are already answered in the docs or somewhere else and can be found with some research. Your questions should reflect that you’ve actually thought through what you’re asking and done some rudimentary research.
  • Most of all don’t forget to have fun and interact with the community. The community is as big a part of Open Source as the code itself.

What to expect if you are chosen

  • All students should join the #kivy and the #kivy-dev irc channels daily, this is how the development team communicates both internally and with the users.
  • You and your mentors will agree on two week milestones for the duration of the summer.
  • Development will occur in your fork of the master branch of Kivy, we expect you to submit at least one PR a week from your branch into a branch reserved for you in the primary repo. This will be your forum for reporting progress as well as documenting any struggles you may have encountered.
  • Missing 2 weekly PR or 2 milestones will result in your failure unless there have been extenuating circumstances. If something comes up, please inform your mentors as soon as possible. If a milestone seems out of reach we will work with you to reevaluate the goals.
  • Your changes will be merged into master once the project has been completed and we have thoroughly tested on every platform that is relevant!