Build options

This page contains instructions for using different build options.

Python versions

python-for-android supports using Python 3.7 or higher. To explicitly select a Python version in your requirements, use e.g. --requirements=python3==3.7.1,hostpython3==3.7.1.

The last python-for-android version supporting Python2 was v2019.10.06

Python-for-android no longer supports building for Python 3 using the CrystaX NDK. The last python-for-android version supporting CrystaX was 0.7.0

Bootstrap options

python-for-android supports multiple app backends with different types of interface. These are called bootstraps.

Currently the following bootstraps are supported, but we hope that it should be easy to add others if your project has different requirements. Let us know if you’d like help adding a new one.

sdl2

Use this with --bootstrap=sdl2, or just include the sdl2 recipe, e.g. --requirements=sdl2,python3.

SDL2 is a popular cross-platform depelopment library, particularly for games. It has its own Android project support, which python-for-android uses as a bootstrap, and to which it adds the Python build and JNI code to start it.

From the point of view of a Python program, SDL2 should behave as normal. For instance, you can build apps with Kivy or PySDL2 and have them work with this bootstrap. It should also be possible to use e.g. pygame_sdl2, but this would need a build recipe and doesn’t yet have one.

Build options

The sdl2 bootstrap supports the following additional command line options (this list may not be exhaustive):

• --private: The directory containing your project files.
• --package: The Java package name for your project. e.g. org.example.yourapp.
• --name: The app name.
• --version: The version number.
• --orientation: Usually one of portait, landscape, sensor to automatically rotate according to the device orientation, or user to do the same but obeying the user’s settings. The full list of valid options is given under android:screenOrientation in the Android documentation.
• --icon: A path to the png file to use as the application icon.
• --permission: A permission name for the app, e.g. --permission VIBRATE. For multiple permissions, add multiple --permission arguments.
• --meta-data: Custom key=value pairs to add in the application metadata.
• --presplash: A path to the image file to use as a screen while the application is loading.
• --presplash-color: The presplash screen background color, of the form #RRGGBB or a color name red, green, blue etc.
• --presplash-lottie: use a lottie (json) file as a presplash animation. If used, this will replace the static presplash image.
• --wakelock: If the argument is included, the application will prevent the device from sleeping.
• --window: If the argument is included, the application will not cover the Android status bar.
• --blacklist: The path to a file containing blacklisted patterns that will be excluded from the final APK. Defaults to ./blacklist.txt.
• --whitelist: The path to a file containing whitelisted patterns that will be included in the APK even if also blacklisted.
• --add-jar: The path to a .jar file to include in the APK. To include multiple jar files, pass this argument multiple times.
• --intent-filters: A file path containing intent filter xml to be included in AndroidManifest.xml.
• --service: A service name and the Python script it should run. See Arbitrary service scripts.
• --add-source: Add a source directory to the app’s Java code.
• --no-compile-pyo: Do not optimise .py files to .pyo.
• --enable-androidx: Enable AndroidX support library.

webview

You can use this with --bootstrap=webview, or include the webviewjni recipe, e.g. --requirements=webviewjni,python3.

The webview bootstrap gui is, per the name, a WebView displaying a webpage, but this page is hosted on the device via a Python webserver. For instance, your Python code can start a Flask application, and your app will display and allow the user to navigate this website.

Note

Your Flask script must start the webserver without :code:debug=True. Debug mode doesn’t seem to work on Android due to use of a subprocess.

This bootstrap will automatically try to load a website on port 5000 (the default for Flask), or you can specify a different option with the –port command line option. If the webserver is not immediately present (e.g. during the short Python loading time when first started), it will instead display a loading screen until the server is ready.

• --private: The directory containing your project files.
• --package: The Java package name for your project. e.g. org.example.yourapp.
• --name: The app name.
• --version: The version number.
• --orientation: Usually one of portait, landscape, sensor to automatically rotate according to the device orientation, or user to do the same but obeying the user’s settings. The full list of valid options is given under android:screenOrientation in the Android documentation.
• --icon: A path to the png file to use as the application icon.
• --permission: A permission name for the app, e.g. --permission VIBRATE. For multiple permissions, add multiple --permission arguments.
• --meta-data: Custom key=value pairs to add in the application metadata.
• --presplash: A path to the image file to use as a screen while the application is loading.
• --presplash-color: The presplash screen background color, of the form #RRGGBB or a color name red, green, blue etc.
• --wakelock: If the argument is included, the application will prevent the device from sleeping.
• --window: If the argument is included, the application will not cover the Android status bar.
• --blacklist: The path to a file containing blacklisted patterns that will be excluded from the final APK. Defaults to ./blacklist.txt.
• --whitelist: The path to a file containing whitelisted patterns that will be included in the APK even if also blacklisted.
• --add-jar: The path to a .jar file to include in the APK. To include multiple jar files, pass this argument multiple times.
• --intent-filters: A file path containing intent filter xml to be included in AndroidManifest.xml.
• --service: A service name and the Python script it should run. See Arbitrary service scripts.
• add-source: Add a source directory to the app’s Java code.
• --port: The port on localhost that the WebView will access. Defaults to 5000.

service_library

You can use this with --bootstrap=service_library option.

This bootstrap can be used together with aar output target to generate a library, containing Python services that can be used with other build systems and frameworks.

• --private: The directory containing your project files.
• --package: The Java package name for your project. e.g. org.example.yourapp.
• --name: The library name.
• --version: The version number.
• --service: A service name and the Python script it should run. See Arbitrary service scripts.
• --blacklist: The path to a file containing blacklisted patterns that will be excluded from the final AAR. Defaults to ./blacklist.txt.
• --whitelist: The path to a file containing whitelisted patterns that will be included in the AAR even if also blacklisted.
• --add-jar: The path to a .jar file to include in the APK. To include multiple jar files, pass this argument multiple times.
• add-source: Add a source directory to the app’s Java code.

Requirements blacklist (APK size optimization)

To optimize the size of the .apk file that p4a builds for you, you can blacklist certain core components. Per default, p4a will add python with batteries included as would be expected on desktop, including openssl, sqlite3 and other components you may not use.

To blacklist an item, specify the --blacklist-requirements option:

p4a apk ... --blacklist-requirements=sqlite3

At the moment, the following core components can be blacklisted (if you don’t want to use them) to decrease APK size:

• android disables p4a’s android module (see android for Android API access)
• libffi disables ctypes stdlib module
• openssl disables ssl stdlib module
• sqlite3 disables sqlite3 stdlib module