chicken-android-sdl2 builder Dockerfile

You can now run CHICKEN and SDL2 on Android devices with greater ease. This project will let you build your own docker image which can build android apps for you. Inside the docker image you'll find:

• and Android project template (with an AndroidManifest.xml and everything else you love)
• Android SDK and api-level 19
• Android NDK r10e
• cross chicken-4.12.0 (builds eggs suitable for armeabi Android)
• SDL2.0.5 (on the host and libSDL2.so on Android)
• sdl2 egg 0.2.0

Making the docker image

user@host $ git clone https://github.com/chicken-mobile/chicken-sdl2-android-builder
user@host $ cd chicken-sdl2-android-builder
user@host $ docker build -t chicken/chicken-sdl2-android-builder:0.1 .

Then leave this beast for a while. The build takes half an hour on my machine, and the ending docker image will be a horrifying 6GB or so. It will also download large quantities of data :-(

Once built though, you should have to tools ready to make an Android app that should actually work.

Setup project

Your "game" sources should be at the root of the project directory, and the android build project should be under android. Let's have a loot at the bundled example:

user@host $ cd examples/basic/main.scm

main.scm should work on your host development machine, provided you have the sdl2 egg installed:

user@host $ chicken-install -s sdl2
user@host $ csi main.scm # note no -s

You don't need to test that it's working on you host machine, but this is probably a good idea. Back to building this as an Android app:

user@host $ docker run -it --rm -v $PWD:/data/app -e HOST_USER_ID=`id -u` chicken/chicken-sdl2-android-builder:0.1 bash

This command is a mouthful. You may want to put it in a Makefile.

Now you should be in a Android environment suited to build your app. We mounted our host project in /data/app so that we can access the "game" sources and so that we can get build artifacts from the container.

HOST_USER_ID allows the container to chown back to your user, so that all build artifacts won't be owned by root.

The docker image contains an Android project template which we copy over. We only need to do this once per app:

root@builder $ pwd
/data/app
root@builder $ cp -r /data/template/ android
root@builder $ ls -l
total 4
drwxr-xr-x 5 root root   240 May 18 00:13 android
-rw-r--r-- 1 1000 users 1350 May 18 00:10 main.scm

It's probably a good idea, at least for non-trivial games, to commit this android project template into your verion-control system.

Building the APK

To build from within the container:

root@builder $ cd /data/app/android/
root@builder $ build.sh

If everything goes as planned, this should produce an SDLActivity-debug.apk. build.sh is just a simple wrapper for ndk-build, ant debug and some cleanup.

Installing the APK

If volumes were mounted properly, the build artifacts are available on our host machine:

user@host $ adb uninstall org.libsdl.app # re-install doesn't work yet :(
user@host $ adb install android/bin/SDLActivity-debug.apk

For this part you'll need some Android tools on the host system in order to install the app, or send the apk to your phone and install it there ("allow external sources" must be on in settings). I don't know how to do adb install from within the docker image.

TODO

• sdl2-egg: make-surface fails on 32bit platforms
• make the resulting docker image much, much smaller (now it's 6GB)
• provide conventions for bundling assets and resources
• fix WARNING: linker: unused DT entry: type 0x1d arg 0x2b1 as discussed here
• support multiple architectures (our natives are only armeabi, see Application.mk)