Unexpected-Keyboard/CONTRIBUTING.md

# Contributing

Thanks for contributing :)

## Building the app

The application doesn't use Gradle and it might be hard to use some features of
Android Studio.

Fortunately, there's not many dependencies:
- OpenJDK 8
- Android SDK: build tools `30.0.3`, platform `30`
- Make sure to have the `$ANDROID_HOME` environment variable set.

For Nix users, there's a `shell.nix` for setting-up the right environment.

Building the debug apk:

```sh
make
```

If the build succeed, the debug apk is located in
`_build/juloo.keyboard2.debug.apk`.

## Debugging on your phone

First [Enable adb debugging on your device](https://developer.android.com/studio/command-line/adb#Enabling).
Then connect your phone to your computer using an USB cable or wireless
debugging.

And finally, install the application with:
```sh
make installd
```

The debug version of the application won't be removed, both versions will stay
installed at the same time.

The application must be enabled in the settings:
System > Languages & input > On-screen keyboard > Manage on-screen keyboards.

## Debugging the application: INSTALL_FAILED_UPDATE_INCOMPATIBLE

`make installd` can fail with the following error message:

```
adb: failed to install _build/juloo.keyboard2.debug.apk: Failure [INSTALL_FAILED_UPDATE_INCOMPATIBLE: Package juloo.keyboard2.debug signatures do not match previously installed version; ignoring!]
make: *** [Makefile:20: installd] Error 1
```

The application can't be "updated" because the temporary certificate has been
lost. The solution is to uninstall and install again.
The application must be enabled again in the settings.

```sh
adb uninstall juloo.keyboard2.debug
make installd
```