Developing Android Apps completely in Python (EuroPython 2012 Training)

At this year's EuroPython conference in Florence, Italy, I've been giving a half-day training about Python application development on Android. The training was 240 minutes long and took place on Tuesday July 3rd 2012 at 09:00.

Photo credit: Stefan Kögl

Summary

The goal of this training is to show you how to start developing full Android applications using only Python. Different technologies will be demonstrated, including PySide-based QML GUIs using the Necessitas Qt port and the Py4A/SL4A-based approach, which can be combined with Android’s WebKit and re-use Python web frameworks.

While Android already has a good SDK out of the box, being able to use Python instead of Java is a big advantage for some developers - it allows for quicker turnaround times, and reuse of Python libraries. Python on Android uses a native CPython build, so its performance and compatibility is very good. Combined with PySide (which uses a native Qt build) and Qt’s support for OpenGL ES acceleration, you can create fluent UIs even with Python.

The resulting PySide-based applications run on Android, but also at least on Mac OS X, Windows, Linux and Maemo and MeeGo - basically all platforms on which Qt is available. The SL4A/Py4A-based applications will run on Android only, but will be able to utilize Android-specific APIs. Both approaches can also be combined.

Code downloads

mygame.py - PGS4A example
launcher.c - C wrapper/launcher
run_gpodder.py - gPodder launcher

Prepare yourself

To get started, you have to download some packages to your host computer, so you can develop and deploy your Python packages to your Android device:

SL4A: sl4a_r5.apk on your device
PGS4A: .tar.bz2 or .zip then python android.py installsdk
Py4A: hg clone https://code.google.com/p/python-for-android/
Native SDK (NDK): Download on your host
Java SDK: Download on your host

Video (second part only)

Unfortunately, due to technical problems, the first part of the video is not available online. The second part can be found here:

Developing Android apps completely in Python part 2 (YouTube)

Questions from the break

How to install the Android emulator

Don't forget to install the "Android Platform Tools" via $SDK/tools/android!

http://developer.android.com/tools/devices/
$SDK/tools/android avd # "android virtual devices"
create emulator
start emulator
"adb devices" shows emulator too

Where to get SL4A for your Android device

Then, to install via adb:

adb install Downloads/sl4a_r5.apk
adb install Downloads/PythonForAndroid_r5.apk

How to install PySide on Mac OS X

See the instructions in the Qt Project Wiki: PySide Binaries for Mac OS X

Other useful instructions

Building CTypes for PGS4A

hg clone https://code.google.com/p/android-python27/

Look into README, copy the environment variable setting + fix paths:

source environment.sh
bash bootstrap.sh
bash build.sh
cp Python/build/lib.linux-i686-2.7/_ctypes.so /path/to/pgs4a/private/
cp -rpv Python/Lib/ctypes ~/src/pgs4a-0.9.4/private/lib/
cd /path/to/pgs4a/
rm -rf private/lib/ctypes/test

Running Python from ADB shell

cd /data/data/com.googlecode.pythonforandroid/files/python/bin
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/data/data/com.googlecode.pythonforandroid/files/python/lib

PGS4A notes

Change "android-8" to "android-15" to install the right platform
Symlink "android-15" from Android SDK into pgs4a/android-sdk/platforms
To initialize: python android.py configure mygame (will write a file .android.json)
To build and deploy: python android.py build mygame release install

Py4A notes

http://code.google.com/p/python-for-android/wiki/BuildingPython
export ANDROID_NDK=~/pkg/android-ndk-r8/
export PATH=$PATH:$ANDROID_NDK:$ANDROID_NDK/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86/

Links

Thomas Perl | contact | 2012 | thp.io