Docs: Document Android build steps

README.md

@@ -55,3 +55,86 @@ To run without ninja rule:
 export SERENITY_SOURCE_DIR=${PWD}/Build/serenity
 ./Build/ladybird
 ```
+
+## Experimental Android Build Steps
+
+### Prepping Qt Creator
+
+In order to build an Android APK, the following additional dependencies are required/recommended:
+
+* Qt Creator 6.4.0 (dev branch)
+* Android Studio 2021.2 (dev branch)
+
+Note that Qt Creator 6.3.x LTS does NOT have the required fix to [QTBUG-104580](https://bugreports.qt.io/browse/QTBUG-104580) as of 2022-07-16 in order to use NDK 24.
+
+The build configuration was tested with the following pacakges from the Android SDK:
+
+* Android Platform and Build Tools version 33
+* Android System Images for API 33 aka ``"system-images;android-33;google-apis;x86_64"``
+* Android NDK 24.0.8215888 for the llvm-14 based toolchain
+
+In order to build ladybird for cross compilation, a separate serenity checkout is recommended.
+
+e.g.
+```
+cd ~/Repos
+git clone https://github.com/SerenityOS/serenity
+```
+
+First create a LagomTools build:
+
+```
+cmake -GNinja -S /path/to/serenity -B BuildTools -Dpackage=LagomTools -DCMAKE_INSTALL_PREFIX=tool-install
+ninja -C BuildTools install
+```
+
+Next, create a build configuration in Qt Creator that uses an ``Android Qt 6.4.0 Debug x86_64`` Kit by following the instructions [here](https://doc.qt.io/qt-6/android-getting-started.html).
+
+Ensure that you get Android API 30 or higher, and Android NDK 24 or higher. In the initial standup, an API 33 SDK for Android 13 was used.
+
+Setup Android device settings in Qt Creator following this [link](https://doc.qt.io/qtcreator/creator-developing-android.html). Note that Qt Creator might not like the Android NDK version 24 we downloaded earlier, as it's "too new" and "not supported". No worries, we can force it to like our version by editing the ``sdk_defintions.json`` file as described uner [Viewing Android Tool Chain Settings](https://doc.qt.io/qtcreator/creator-developing-android.html#viewing-android-tool-chain-settings)
+
+The relevant snippets of that JSON file are reproduced below. Just have to make sure it's happy with "platforms;android-33" and the exact installed NDK version.
+
+```json
+ "sdk_essential_packages": {
+ "default": ["platform-tools", "platforms;android-33", "cmdline-tools;latest"],
+ "linux": [],
+ "mac": [],
+ "windows": ["extras;google;usb_driver"]
+ }
+ },
+ "specific_qt_versions": [
+ {
+ "versions": ["default"],
+ "sdk_essential_packages": ["build-tools;33.0.0", "ndk;24.0.8215888"],
+ "ndk_path": "ndk/24.0.8215888"
+ },
+```
+
+
+### Building Ladybird for Android
+
+Next, we can select the ``Android Qt 6.4.0 Debug x86_64`` Kit under the Projects tab of the Qt Creator, and watch CMake have a bad time because we need to edit the configuration.
+
+In the ``Initial Configuration`` Tab of the CMake configuration for the Kit, edit the following initial values:
+
+* ANDROID_NATIVE_API_LEVEL: 23 --> 30
+* LagomTools_DIR: New Directory setting, set to `/path/to/ladybird/tool-install/share/Lagom` for the LagomTools build we created earlier
+* SERENITY_SOURCE_DIR: New path setting, set to your local serenity checkout
+
+Make sure to click the ``Reconfigure With Initial Parameters`` button, and triple check you've been editing the ``Initial Configuration`` tab and not the ``Current Configuration`` one.
+
+Build the project, and cross your fingers that it all works :)
+
+### Running the Android APK
+
+In order to run the ladybird application, first make sure that the Debug settings in the bottom left of the Qt Creator window are trying to debug ladybird, and not another Lagom target, like LibArchive.
+
+Create an Android device to test using the Tools->Options->Devices->Devices add button. This will only work for an Android device if the ``"system-images;android-33;google-apis;x86_64"`` or similar package is installed with the Android SDK ``sdkmanager`` tool.
+
+Open up Android Studio, and in the Device Manager edit the created AVD to update its Internal Storage under Advanced Settings. Make sure it's at least 1 GiB. The default of 800 MiB is generally too small to install ladybird.
+
+Hit the Debug or Run green arrows and hope for the best!
+
+With luck the application should start up, install the required resources into the internal storage from the APK, and open up the default webpage. Clicking the home button to load serenityos.org should work.