BoardBridge

A modern, native EGL / Surface bridge for Android: it binds an Android Surface to an OpenGL ES 3.2 context in C++, drives it from a dedicated render thread, and handles the full surface lifecycle and input dispatch.

BoardBridge modernizes the Surface-to-GL approach of Boardwalk by zhuowei (Apache-2.0). It targets current Android (Android 15 / API 35) and Mali-G52 / Helio G85 class devices.

Note on Boardwalk: the original (archived) Boardwalk did not hand-write an EGL bridge — it subclassed the framework GLSurfaceView and let the framework bind the Surface and manage EGL, while its native code did Dalvik VM tweaks. BoardBridge takes that GLSurfaceView pattern as the conceptual seed and rebuilds it natively. See docs/DESIGN.md for the full analysis and the modernization table.

What it does

• Surface → EGLSurface binding in native code via ANativeWindow_fromSurface
  • eglCreateWindowSurface, with an ES 3.2 context (3.1 / 3.0 fallback).
• Thread-safe surface lifecycle: surfaceCreated / Changed / Destroyed are marshaled to a dedicated render thread; surfaceDestroyed blocks until the native side releases the window, preventing use-after-free.
• Input dispatch: touch (per-pointer) and key events flow through a bounded native queue and are consumed each frame.
• Live demo: a spinning GLES 3.00 shader triangle over an animated clear color — touch steers the color, key presses shift the hue.

Architecture

MainActivity ─ BridgeSurfaceView (SurfaceView + SurfaceHolder.Callback + input)
        │  JNI (NativeBridge)
        ▼
native_bridge.cpp ─▶ RenderThread ─▶ EglCore (EGL + GLES 3.2)
                          └─ InputQueue

• Kotlin: app/src/main/java/com/boardbridge/egl/
• Native C++: app/src/main/cpp/ (native_bridge, render_thread, egl_core, input_queue)

Requirements

compileSdk / targetSdk	35 (Android 15)
minSdk	26
NDK	r27c (27.2.12479018) — 16 KB page aligned
CMake	3.22.1
ABIs	arm64-v8a (primary), armeabi-v7a, x86_64
GPU	OpenGL ES 3.2 (e.g. Mali-G52)

Building

The canonical build uses the Gradle wrapper (no Android Studio required):

./gradlew :app:assembleDebug
# output: app/build/outputs/apk/debug/app-debug.apk

Why CI builds this

This project is developed on an aarch64 Android phone (in a proot Linux environment). The Android SDK build-tools available there are x86-64 binaries that cannot execute on aarch64, so a local ./gradlew build is not possible on the device. The build therefore runs on GitHub Actions (an ubuntu-latest runner), which installs the NDK + CMake and runs the exact same ./gradlew :app:assembleDebug. See .github/workflows/build.yml. The built app-debug.apk is uploaded as a workflow artifact.

To build locally on a normal x86-64 Linux/macOS/Windows machine, install the Android SDK (API 35), accept licenses, point ANDROID_HOME at it (or add a local.properties with sdk.dir=...), and run the command above; Gradle/AGP will fetch NDK r27c and CMake 3.22.1 as needed.

Credits & license

• Boardwalk by zhuowei — Apache-2.0. The conceptual origin of the Surface/GL bridge modernized here.
• The Android Open Source Project — Apache-2.0 (original Boardwalk headers).

BoardBridge is licensed under the Apache License, Version 2.0. See LICENSE and NOTICE.