Heaps Android

An Android Studio project for a simple Heaps.io application. If you're using the latest versions of Haxe, Heaps, and Hashlink, building an Android app should be as simple as copying the compiled C code into the project and building it.

This project wouldn't be possible without the work done by: https://github.com/altef/heaps-android

Structure

.
├── app/             		
|   └── src/                     	
|   |   └── main/			# This is where the code goes, split by language.
|   |       ├── cpp/		# Various libraries are here, plus the C generated from your Haxe.
|   |       |   └── out/    # Put your generated C code in here. The folder is not included in Git, as it's what you generate and move from Heaps.
|   |       ├── haxe/
|   |       ├── java/		# Some necessary Java classes.
|   |       ├── res/
|   |       └── AndroidManifest.xml 
|   └── build.gradle                
├── gradle/          		# Generated by Android Studio.
├── heaps-src/          	# An example Heaps project. Bare minimum you need to generate the C code, plus some helper methods for handling input and save files.
├── ...
└── README.md

Usage

1. Clone/download the repo along with the submodules and subtrees: git clone --recursive https://github.com/4as/heaps-android

2. Open the directory in Android Studio. For reference, the project has been successfully built with Android Studio Panda 1 | 2025.3.1 RC 1.

3. Make sure you have the NDK and CMake installed - you can do this in Android Studio, by going to Tools > SDK Manager, and then clicking the SDK Tools tab. Make sure NDK (side by side) and CMake are selected.

4. The project is configured to run the current version of NDK 27.3.13750724 and CMAKE 3.10.2. Android Studio should download them for you in the previous step; you just need to set the correct versions in build.gradle. Alternatively, you can download a specific version from here: developer.android.com/ndk/downloads, or if it becomes outdated in the future, from here: github.com/android/ndk/wiki/Unsupported-Downloads. A manually downloaded NDK needs to be placed in ndk directory inside your Android SDK directory. You can find it under File > Project Structure and then SDK Location.

5. Compile your app to C and place the generated code inside the /app/src/cpp/out directory. I highly recommend checking out the example app in the /heaps-src directory, as it contains not only the configuration, but also some helper methods you might find useful in your own project. The helper methods include software keyboard handling (which current Heaps doesn't provide) and the ability to retrieve a writable directory for save files and similar data.

6. Build the project. If you have a mobile device connected to your machine, you could even try pressing the run button to test it directly.

Changes overview

Making the project work took a lot of experimentation. If something doesn't work, I probably won't be able to help. Here are some things I've changed to fix the compilation issues:

1. Updated SDL to version 2.32.2 and removed android-project-ant. SDL is added to the repo as a subtree, to allow for those changes.
2. Updated OpenAL-soft to version 1.21.0. It is included as a subtree to fix compatibility issues and remove examples.
3. Finally, the biggest change was including Hashlink's 1.15.0 repo as subtree to update various libraries and includes.

To be more specific Hashlink required the following changes:

1. Updated LibUV to use the full 1.9.1 source code. For some reason, Hashlink's repo doesn't include unix files (only win), which are needed for Android.
2. Updated PCRE to 10.45 and fixed various configuration problems. This was by far the hardest thing to get working. By default, PCRE attempts to use JIT functions, which Android does not support, so they had to be disabled completely. However, this led to compilation errors, so I ultimately removed them and provided stubs (in cpp/stubs.c) to allow the project to compile. I honestly have no idea what the proper long-term solution should be...
3. Pulled some additional changes from HashLink's repo committed after 1.15 was released. Some reported issues were relevant to the compilation errors I was having, so the current code is made up of random patches.

Project overview

The entry point to the application is in the HeapsActivity class, which extends SDLActivity. SDL is what connects the Java code to native C - it calls SDL_main() inside the cpp/jni.c file, which in turn calls hl_entry_point() located in your cpp/out/game.c file, the one exported from Heaps along with the rest of your application.

Self-promotion

The project was used to realase Yeet My Darknesss on Itch.io.