Getting Started

Getting up and running on python-for-android (p4a) is a simple process and should only take you a couple of minutes. We’ll refer to Python for android as p4a in this documentation.

Concepts

Basic:

  • requirements: For p4a, all your app’s dependencies must be specified via --requirements similar to the standard requirements.txt. (Unless you specify them via a setup.py/install_requires) All dependencies will be mapped to “recipes” if any exist, so that many common libraries will just work. See “recipe” below for details.
  • distribution: A distribution is the final “build” of your compiled project + requirements, as an Android project assembled by p4a that can be turned directly into an APK. p4a can contain multiple distributions with different sets of requirements.
  • build: A build refers to a compiled recipe or distribution.
  • bootstrap: A bootstrap is the app backend that will start your application. The default for graphical applications is SDL2. You can also use e.g. the webview for web apps, or service_only for background services. Different bootstraps have different additional build options.

Advanced:

  • recipe: A recipe is a file telling p4a how to install a requirement that isn’t by default fully Android compatible. This is often necessary for Cython or C/C++-using python extensions. p4a has recipes for many common libraries already included, and any dependency you specified will be automatically mapped to its recipe. If a dependency doesn’t work and has no recipe included in p4a, then it may need one to work.

Installation

Installing p4a

p4a is now available on Pypi, so you can install it using pip:

pip install python-for-android

You can also test the master branch from Github using:

pip install git+https://github.com/kivy/python-for-android.git

Installing Dependencies

p4a has several dependencies that must be installed:

  • git
  • ant
  • python2
  • cython (can be installed via pip)
  • a Java JDK (e.g. openjdk-8)
  • zlib (including 32 bit)
  • libncurses (including 32 bit)
  • unzip
  • virtualenv (can be installed via pip)
  • ccache (optional)
  • autoconf (for ffpyplayer_codecs recipe)
  • libtool (for ffpyplayer_codecs recipe)
  • cmake (required for some native code recipes like jpeg’s recipe)

On recent versions of Ubuntu and its derivatives you may be able to install most of these with:

sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get install -y build-essential ccache git zlib1g-dev python2.7 python2.7-dev libncurses5:i386 libstdc++6:i386 zlib1g:i386 openjdk-8-jdk unzip ant ccache autoconf libtool

On Arch Linux (64 bit) you should be able to run the following to install most of the dependencies (note: this list may not be complete). gcc-multilib will conflict with (and replace) gcc if not already installed:

sudo pacman -S jdk7-openjdk python2 python2-pip python2-kivy mesa-libgl lib32-mesa-libgl lib32-sdl2 lib32-sdl2_image lib32-sdl2_mixer sdl2_ttf unzip gcc-multilib gcc-libs-multilib

Installing Android SDK

Warning

python-for-android is often picky about the SDK/NDK versions. Pick the recommended ones from below to avoid problems.

Basic SDK install

You need to download and unpack the Android SDK and NDK to a directory (let’s say $HOME/Documents/):

For the Android SDK, you can download ‘just the command line tools’. When you have extracted these you’ll see only a directory named tools, and you will need to run extra commands to install the SDK packages needed.

For Android NDK, note that modern releases will only work on a 64-bit operating system. The minimal, and recommended, NDK version to use is r19b:

  • Go to ndk downloads page
  • Windows users should create a virtual machine with an GNU Linux os installed, and then you can follow the described instructions from within your virtual machine.

Platform and build tools

First, install an API platform to target. The recommended *target* API level is 27, you can replace it with a different number but keep in mind other API versions are less well-tested and older devices are still supported down to the recommended specified *minimum* API/NDK API level 21:

$SDK_DIR/tools/bin/sdkmanager "platforms;android-27"

Second, install the build-tools. You can use $SDK_DIR/tools/bin/sdkmanager --list to see all the possibilities, but 28.0.2 is the latest version at the time of writing:

$SDK_DIR/tools/bin/sdkmanager "build-tools;28.0.2"

Configure p4a to use your SDK/NDK

Then, you can edit your ~/.bashrc or other favorite shell to include new environment variables necessary for building on android:

# Adjust the paths!
export ANDROIDSDK="$HOME/Documents/android-sdk-27"
export ANDROIDNDK="$HOME/Documents/android-ndk-r19b"
export ANDROIDAPI="27"  # Target API version of your application
export NDKAPI="21"  # Minimum supported API version of your application
export ANDROIDNDKVER="r10e"  # Version of the NDK you installed

You have the possibility to configure on any command the PATH to the SDK, NDK and Android API using:

  • --sdk-dir PATH as an equivalent of $ANDROIDSDK
  • --ndk-dir PATH as an equivalent of $ANDROIDNDK
  • --android-api VERSION as an equivalent of $ANDROIDAPI
  • --ndk-api VERSION as an equivalent of $NDKAPI
  • --ndk-version VERSION as an equivalent of $ANDROIDNDKVER

Usage

Build a Kivy or SDL2 application

To build your application, you need to specify name, version, a package identifier, the bootstrap you want to use (sdl2 for kivy or sdl2 apps) and the requirements:

p4a apk --private $HOME/code/myapp --package=org.example.myapp --name "My application" --version 0.1 --bootstrap=sdl2 --requirements=python3,kivy

Note on --requirements: you must add all libraries/dependencies your app needs to run. Example: --requirements=python3,kivy,vispy. For an SDL2 app, kivy is not needed, but you need to add any wrappers you might use (e.g. pysdl2).

This p4a apk … command builds a distribution with python3, kivy, and everything else you specified in the requirements. It will be packaged using a SDL2 bootstrap, and produce an .apk file.

Compatibility notes:

  • While python2 is still supported by python-for-android, it will possibly no longer receive patches by the python creators themselves in 2020. Migration to Python 3 is recommended!

Build a WebView application

To build your application, you need to have a name, version, a package identifier, and explicitly use the webview bootstrap, as well as the requirements:

p4a apk --private $HOME/code/myapp --package=org.example.myapp --name "My WebView Application" --version 0.1 --bootstrap=webview --requirements=flask --port=5000

Please note as with kivy/SDL2, you need to specify all your additional requirements/dependencies.

You can also replace flask with another web framework.

Replace --port=5000 with the port on which your app will serve a website. The default for Flask is 5000.

Other options

You can pass other command line arguments to control app behaviours such as orientation, wakelock and app permissions. See Bootstrap options.

Rebuild everything

If anything goes wrong and you want to clean the downloads and builds to retry everything, run:

p4a clean_all

If you just want to clean the builds to avoid redownloading dependencies, run:

p4a clean_builds && p4a clean_dists

Getting help

If something goes wrong and you don’t know how to fix it, add the --debug option and post the output log to the kivy-users Google group or the kivy #support Discord channel.

See Troubleshooting for more information.

Advanced usage

Recipe management

You can see the list of the available recipes with:

p4a recipes

If you are contributing to p4a and want to test a recipes again, you need to clean the build and rebuild your distribution:

p4a clean_recipe_build RECIPENAME
p4a clean_dists
# then rebuild your distribution

You can write “private” recipes for your application, just create a p4a-recipes folder in your build directory, and place a recipe in it (edit the __init__.py):

mkdir -p p4a-recipes/myrecipe
touch p4a-recipes/myrecipe/__init__.py

Distribution management

Every time you start a new project, python-for-android will internally create a new distribution (an Android build project including Python and your other dependencies compiled for Android), according to the requirements you added on the command line. You can force the reuse of an existing distribution by adding:

p4a apk --dist_name=myproject ...

This will ensure your distribution will always be built in the same directory, and avoids using more disk space every time you adjust a requirement.

You can list the available distributions:

p4a distributions

And clean all of them:

p4a clean_dists

Configuration file

python-for-android checks in the current directory for a configuration file named .p4a. If found, it adds all the lines as options to the command line. For example, you can add the options you would always include such as:

--dist_name my_example
--android_api 27
--requirements kivy,openssl

Overriding recipes sources

You can override the source of any recipe using the $P4A_recipename_DIR environment variable. For instance, to test your own Kivy branch you might set:

export P4A_kivy_DIR=/home/username/kivy

The specified directory will be copied into python-for-android instead of downloading from the normal url specified in the recipe.

setup.py file (experimental)

If your application is also packaged for desktop using setup.py, you may want to use your setup.py instead of the --requirements option to avoid specifying things twice. For that purpose, check out distutils/setuptools integration

Going further

See the other pages of this doc for more information on specific topics: