Android: decouple JNI setup from unused subsystems#15895
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Query the natively compiled-in subsystems at runtime so the Java side only registers and initializes the managers that exist, fixing UnsatisfiedLinkError when SDL is built with a subsystem disabled (e.g. -DSDL_AUDIO_DISABLED). - SDL.setupJNI() calls nativeGetCompiledSubsystems() and skips SDLAudioManager/SDLControllerManager setup for absent subsystems. - Gate SDLControllerManager.initializeDeviceListener() and the joystick key-event path on the controller subsystem; gate the clipboard handler on video, mirroring the native guards. - Guard the SDLControllerManager JNI bindings with SDL_ANDROID_NEED_CONTROLLER_MANAGER (joystick or haptic enabled). - Reorganize SDL_android.h/.c into guarded per-subsystem groups with matching ordering.
slouken
reviewed
Jun 28, 2026
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| if ((subsystems & SDL_INIT_AUDIO) != 0) { | ||
| int compiled = SDLActivity.nativeGetCompiledSubsystems(); | ||
| mInitializedSubsystems = subsystems & compiled; |
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| mInitializedSubsystems = subsystems & compiled; | |
| mInitializedSubsystems = (subsystems & compiled); |
slouken
reviewed
Jun 28, 2026
| // C functions we call | ||
| public static native String nativeGetVersion(); | ||
| public static native void nativeSetupJNI(); | ||
| public static native int nativeGetCompiledSubsystems(); |
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@HTRamsey, @AntTheAlchemist, do we need to do something with proguard here?
slouken
reviewed
Jun 28, 2026
| SDLActivity.getContentView().requestPointerCapture(); | ||
| } else { | ||
| SDLActivity.getContentView().releasePointerCapture(); | ||
| if (SDLActivity.getContentView() != null) { |
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Please put this into a temporary variable.
slouken
reviewed
Jun 28, 2026
| } | ||
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| if (mRelativeModeEnabled && !SDLActivity.isDeXMode()) { | ||
| if (mRelativeModeEnabled && !SDLActivity.isDeXMode() && SDLActivity.getContentView() != null) { |
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Again, please put this into a temporary variable.
slouken
reviewed
Jun 28, 2026
| return SDL_Unsupported(); | ||
| } | ||
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| #ifndef SDL_HAPTIC_DISABLED |
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Please move this to the top of the function.
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Summary
On Android, JNI setup previously assumed every subsystem was compiled in:
JNI_OnLoad/checkJNIReadywaited on the audio and controller manager classes unconditionally, andSDLActivityalways created a surface, clipboard handler, and controller listeners. As a result a build with subsystems disabled (e.g.-DSDL_VIDEO=OFF,-DSDL_AUDIO=OFF, joystick-only) would either fail to link, stall incheckJNIReady()becauseSDL_SetMainReady()never fired, or crash dereferencing a null surface.This decouples the Android JNI layer from individual subsystems so SDL builds and runs with any subsystem disabled, and supports a headless
SDLActivity(no rendering surface) whenSDL_VIDEO_DISABLEDis set.Changes
C (
src/core/android/)SDL_*_DISABLEDmacros. TheSDLControllerManagertable is gated on joystick (haptic requires joystick, enforced in CMake), audio onSDL_AUDIO_DISABLED, video/input and dialog rows likewise.JNI_OnLoadonly registers the manager classes that are compiled in;checkJNIReady()only waits on the classes that exist, soSDL_SetMainReady()fires in reduced builds.nativeGetCompiledSubsystems()exports the compiled-in subsystem mask to Java so the Java layer can match the native build.Java (
android-project/.../org/libsdl/app/)SDL.setupJNI()intersects the requested subsystems withnativeGetCompiledSubsystems()and only sets up the audio / controller managers whose bits survive — this is what prevents thecheckJNIReady()stall.SDLActivitygates surface, layout, clipboard, drop-file, orientation, and controller-listener setup on the active subsystems, and is null-safe on the lifecycle paths when there is no surface (headless).SDLControllerManageronly builds a haptic handler when haptic is active and null-guards the relative-mouse paths for the headless case.Testing
Built
arm64-v8a,Release, NDK r27,android-21,-DSDL_SHARED=ON, with each subsystem disabled individually plus an all-off "minimal" config. All 13 configurations configure, compile, and link cleanly. StrippedlibSDL3.sosizes (llvm-strip):libSDL3.so(stripped)SDL_POWER=OFFSDL_HAPTIC=OFFSDL_DIALOG=OFFSDL_SENSOR=OFFSDL_CAMERA=OFFSDL_AUDIO=OFFSDL_GPU=OFFSDL_JOYSTICK=OFF+SDL_HAPTIC=OFFSDL_RENDER=OFFSDL_HIDAPI=OFFSDL_VIDEO=OFF(headless)A minimal Android build is roughly 46% smaller than the full library.
Static/build verification is complete across all configs. On-device runtime validation of a headless activity and a controller-only build is still outstanding.