
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 <https://github.com/kivy/python-for-android/archive/v2019.10.06.zip>`__

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 <https://github.com/kivy/python-for-android/archive/0.7.0.zip>`__

.. _bootstrap_build_options:

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
<https://groups.google.com/forum/#!forum/python-android>`__ 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
  <https://developer.android.com/guide/topics/manifest/activity-element.html>`__.
- ``--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 :ref:`arbitrary_scripts_services`.
- ``--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
  <https://developer.android.com/guide/topics/manifest/activity-element.html>`__.
- ``--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 :ref:`arbitrary_scripts_services`.
- ``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 :ref:`arbitrary_scripts_services`.
- ``--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 :ref:`reference-label-for-android-module`)
- ``libffi``  disables ctypes stdlib module
- ``openssl``   disables ssl stdlib module
- ``sqlite3``   disables sqlite3 stdlib module
