src/core/android/SDL_android.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2015 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "../../SDL_internal.h"
#include "SDL_stdinc.h"
#include "SDL_assert.h"
#include "SDL_hints.h"
#include "SDL_log.h"

#ifdef __ANDROID__

#include "SDL_system.h"
#include "SDL_android.h"
#include <EGL/egl.h>

#include "../../events/SDL_events_c.h"
#include "../../video/android/SDL_androidkeyboard.h"
#include "../../video/android/SDL_androidmouse.h"
#include "../../video/android/SDL_androidtouch.h"
#include "../../video/android/SDL_androidvideo.h"
#include "../../video/android/SDL_androidwindow.h"
#include "../../joystick/android/SDL_sysjoystick_c.h"

#include <android/log.h>
#include <pthread.h>
#include <sys/types.h>
#include <unistd.h>
#define LOG_TAG "SDL_android"
/* #define LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__) */
/* #define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__) */
#define LOGI(...) do {} while (0)
#define LOGE(...) do {} while (0)

/* Uncomment this to log messages entering and exiting methods in this file */
/* #define DEBUG_JNI */

static void Android_JNI_ThreadDestroyed(void*);

/*******************************************************************************
 This file links the Java side of Android with libsdl
*******************************************************************************/
#include <jni.h>
#include <android/log.h>


/*******************************************************************************
                               Globals
*******************************************************************************/
static pthread_key_t mThreadKey;
static JavaVM* mJavaVM;

/* Main activity */
static jclass mActivityClass;

/* method signatures */
static jmethodID midGetNativeSurface;
static jmethodID midFlipBuffers;
static jmethodID midAudioInit;
static jmethodID midAudioWriteShortBuffer;
static jmethodID midAudioWriteByteBuffer;
static jmethodID midAudioQuit;
static jmethodID midPollInputDevices;

/* Accelerometer data storage */
static float fLastAccelerometer[3];
static SDL_bool bHasNewData;

/*******************************************************************************
                 Functions called by JNI
*******************************************************************************/

/* Library init */
JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved)
{
    JNIEnv *env;
    mJavaVM = vm;
    LOGI("JNI_OnLoad called");
    if ((*mJavaVM)->GetEnv(mJavaVM, (void**) &env, JNI_VERSION_1_4) != JNI_OK) {
        LOGE("Failed to get the environment using GetEnv()");
        return -1;
    }
    /*
     * Create mThreadKey so we can keep track of the JNIEnv assigned to each thread
     * Refer to http://developer.android.com/guide/practices/design/jni.html for the rationale behind this
     */
    if (pthread_key_create(&mThreadKey, Android_JNI_ThreadDestroyed) != 0) {
        __android_log_print(ANDROID_LOG_ERROR, "SDL", "Error initializing pthread key");
    }
    Android_JNI_SetupThread();

    return JNI_VERSION_1_4;
}

/* Called before SDL_main() to initialize JNI bindings */
JNIEXPORT void JNICALL SDL_Android_Init(JNIEnv* mEnv, jclass cls)
{
    __android_log_print(ANDROID_LOG_INFO, "SDL", "SDL_Android_Init()");

    Android_JNI_SetupThread();

    mActivityClass = (jclass)((*mEnv)->NewGlobalRef(mEnv, cls));

    midGetNativeSurface = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                "getNativeSurface","()Landroid/view/Surface;");
    midFlipBuffers = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                "flipBuffers","()V");
    midAudioInit = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                "audioInit", "(IZZI)I");
    midAudioWriteShortBuffer = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                "audioWriteShortBuffer", "([S)V");
    midAudioWriteByteBuffer = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                "audioWriteByteBuffer", "([B)V");
    midAudioQuit = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                "audioQuit", "()V");
    midPollInputDevices = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
                                "pollInputDevices", "()V");

    bHasNewData = SDL_FALSE;

    if(!midGetNativeSurface || !midFlipBuffers || !midAudioInit ||
       !midAudioWriteShortBuffer || !midAudioWriteByteBuffer || !midAudioQuit || !midPollInputDevices) {
        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL: Couldn't locate Java callbacks, check that they're named and typed correctly");
    }
    __android_log_print(ANDROID_LOG_INFO, "SDL", "SDL_Android_Init() finished!");
}

/* Drop file */
void Java_org_libsdl_app_SDLActivity_onNativeDropFile(
                                    JNIEnv* env, jclass jcls,
                                    jstring filename)
{
    const char *path = (*env)->GetStringUTFChars(env, filename, NULL);
    SDL_SendDropFile(path);
    (*env)->ReleaseStringUTFChars(env, filename, path);
}

/* Resize */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeResize(
                                    JNIEnv* env, jclass jcls,
                                    jint width, jint height, jint format, jfloat rate)
{
    Android_SetScreenResolution(width, height, format, rate);
}

/* Paddown */
JNIEXPORT jint JNICALL Java_org_libsdl_app_SDLActivity_onNativePadDown(
                                    JNIEnv* env, jclass jcls,
                                    jint device_id, jint keycode)
{
    return Android_OnPadDown(device_id, keycode);
}

/* Padup */
JNIEXPORT jint JNICALL Java_org_libsdl_app_SDLActivity_onNativePadUp(
                                   JNIEnv* env, jclass jcls,
                                   jint device_id, jint keycode)
{
    return Android_OnPadUp(device_id, keycode);
}

/* Joy */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeJoy(
                                    JNIEnv* env, jclass jcls,
                                    jint device_id, jint axis, jfloat value)
{
    Android_OnJoy(device_id, axis, value);
}

/* POV Hat */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeHat(
                                    JNIEnv* env, jclass jcls,
                                    jint device_id, jint hat_id, jint x, jint y)
{
    Android_OnHat(device_id, hat_id, x, y);
}


JNIEXPORT jint JNICALL Java_org_libsdl_app_SDLActivity_nativeAddJoystick(
    JNIEnv* env, jclass jcls,
    jint device_id, jstring device_name, jint is_accelerometer, 
    jint nbuttons, jint naxes, jint nhats, jint nballs)
{
    int retval;
    const char *name = (*env)->GetStringUTFChars(env, device_name, NULL);

    retval = Android_AddJoystick(device_id, name, (SDL_bool) is_accelerometer, nbuttons, naxes, nhats, nballs);

    (*env)->ReleaseStringUTFChars(env, device_name, name);
    
    return retval;
}

JNIEXPORT jint JNICALL Java_org_libsdl_app_SDLActivity_nativeRemoveJoystick(
    JNIEnv* env, jclass jcls, jint device_id)
{
    return Android_RemoveJoystick(device_id);
}


/* Surface Created */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeSurfaceChanged(JNIEnv* env, jclass jcls)
{
    SDL_WindowData *data;
    SDL_VideoDevice *_this;

    if (Android_Window == NULL || Android_Window->driverdata == NULL ) {
        return;
    }
    
    _this =  SDL_GetVideoDevice();
    data =  (SDL_WindowData *) Android_Window->driverdata;
    
    /* If the surface has been previously destroyed by onNativeSurfaceDestroyed, recreate it here */
    if (data->egl_surface == EGL_NO_SURFACE) {
        if(data->native_window) {
            ANativeWindow_release(data->native_window);
        }
        data->native_window = Android_JNI_GetNativeWindow();
        data->egl_surface = SDL_EGL_CreateSurface(_this, (NativeWindowType) data->native_window);
    }
    
    /* GL Context handling is done in the event loop because this function is run from the Java thread */
    
}

/* Surface Destroyed */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeSurfaceDestroyed(JNIEnv* env, jclass jcls)
{
    /* We have to clear the current context and destroy the egl surface here
     * Otherwise there's BAD_NATIVE_WINDOW errors coming from eglCreateWindowSurface on resume
     * Ref: http://stackoverflow.com/questions/8762589/eglcreatewindowsurface-on-ics-and-switching-from-2d-to-3d
     */
    SDL_WindowData *data;
    SDL_VideoDevice *_this;
    
    if (Android_Window == NULL || Android_Window->driverdata == NULL ) {
        return;
    }
    
    _this =  SDL_GetVideoDevice();
    data = (SDL_WindowData *) Android_Window->driverdata;
    
    if (data->egl_surface != EGL_NO_SURFACE) {
        SDL_EGL_MakeCurrent(_this, NULL, NULL);
        SDL_EGL_DestroySurface(_this, data->egl_surface);
        data->egl_surface = EGL_NO_SURFACE;
    }
    
    /* GL Context handling is done in the event loop because this function is run from the Java thread */

}

JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_nativeFlipBuffers(JNIEnv* env, jclass jcls)
{
    SDL_GL_SwapWindow(Android_Window);
}

/* Keydown */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeKeyDown(
                                    JNIEnv* env, jclass jcls, jint keycode)
{
    Android_OnKeyDown(keycode);
}

/* Keyup */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeKeyUp(
                                    JNIEnv* env, jclass jcls, jint keycode)
{
    Android_OnKeyUp(keycode);
}

/* Keyboard Focus Lost */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeKeyboardFocusLost(
                                    JNIEnv* env, jclass jcls)
{
    /* Calling SDL_StopTextInput will take care of hiding the keyboard and cleaning up the DummyText widget */
    SDL_StopTextInput();
}


/* Touch */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeTouch(
                                    JNIEnv* env, jclass jcls,
                                    jint touch_device_id_in, jint pointer_finger_id_in,
                                    jint action, jfloat x, jfloat y, jfloat p)
{
    Android_OnTouch(touch_device_id_in, pointer_finger_id_in, action, x, y, p);
}

/* Mouse */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeMouse(
                                    JNIEnv* env, jclass jcls,
                                    jint button, jint action, jfloat x, jfloat y)
{
    Android_OnMouse(button, action, x, y);
}

/* Accelerometer */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_onNativeAccel(
                                    JNIEnv* env, jclass jcls,
                                    jfloat x, jfloat y, jfloat z)
{
    fLastAccelerometer[0] = x;
    fLastAccelerometer[1] = y;
    fLastAccelerometer[2] = z;
    bHasNewData = SDL_TRUE;
}

/* Low memory */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_nativeLowMemory(
                                    JNIEnv* env, jclass cls)
{
    SDL_SendAppEvent(SDL_APP_LOWMEMORY);
}

/* Quit */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_nativeQuit(
                                    JNIEnv* env, jclass cls)
{
    /* Discard previous events. The user should have handled state storage
     * in SDL_APP_WILLENTERBACKGROUND. After nativeQuit() is called, no
     * events other than SDL_QUIT and SDL_APP_TERMINATING should fire */
    SDL_FlushEvents(SDL_FIRSTEVENT, SDL_LASTEVENT);
    /* Inject a SDL_QUIT event */
    SDL_SendQuit();
    SDL_SendAppEvent(SDL_APP_TERMINATING);
    /* Resume the event loop so that the app can catch SDL_QUIT which
     * should now be the top event in the event queue. */
    if (!SDL_SemValue(Android_ResumeSem)) SDL_SemPost(Android_ResumeSem);
}

/* Pause */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_nativePause(
                                    JNIEnv* env, jclass cls)
{
    __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativePause()");
    if (Android_Window) {
        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_FOCUS_LOST, 0, 0);
        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_MINIMIZED, 0, 0);
        SDL_SendAppEvent(SDL_APP_WILLENTERBACKGROUND);
        SDL_SendAppEvent(SDL_APP_DIDENTERBACKGROUND);
    
        /* *After* sending the relevant events, signal the pause semaphore 
         * so the event loop knows to pause and (optionally) block itself */
        if (!SDL_SemValue(Android_PauseSem)) SDL_SemPost(Android_PauseSem);
    }
}

/* Resume */
JNIEXPORT void JNICALL Java_org_libsdl_app_SDLActivity_nativeResume(
                                    JNIEnv* env, jclass cls)
{
    __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "nativeResume()");

    if (Android_Window) {
        SDL_SendAppEvent(SDL_APP_WILLENTERFOREGROUND);
        SDL_SendAppEvent(SDL_APP_DIDENTERFOREGROUND);
        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_FOCUS_GAINED, 0, 0);
        SDL_SendWindowEvent(Android_Window, SDL_WINDOWEVENT_RESTORED, 0, 0);
        /* Signal the resume semaphore so the event loop knows to resume and restore the GL Context
         * We can't restore the GL Context here because it needs to be done on the SDL main thread
         * and this function will be called from the Java thread instead.
         */
        if (!SDL_SemValue(Android_ResumeSem)) SDL_SemPost(Android_ResumeSem);
    }
}

JNIEXPORT void JNICALL Java_org_libsdl_app_SDLInputConnection_nativeCommitText(
                                    JNIEnv* env, jclass cls,
                                    jstring text, jint newCursorPosition)
{
    const char *utftext = (*env)->GetStringUTFChars(env, text, NULL);

    SDL_SendKeyboardText(utftext);

    (*env)->ReleaseStringUTFChars(env, text, utftext);
}

JNIEXPORT void JNICALL Java_org_libsdl_app_SDLInputConnection_nativeSetComposingText(
                                    JNIEnv* env, jclass cls,
                                    jstring text, jint newCursorPosition)
{
    const char *utftext = (*env)->GetStringUTFChars(env, text, NULL);

    SDL_SendEditingText(utftext, 0, 0);

    (*env)->ReleaseStringUTFChars(env, text, utftext);
}

JNIEXPORT jstring JNICALL Java_org_libsdl_app_SDLActivity_nativeGetHint(JNIEnv* env, jclass cls, jstring name) {
    const char *utfname = (*env)->GetStringUTFChars(env, name, NULL);
    const char *hint = SDL_GetHint(utfname);

    jstring result = (*env)->NewStringUTF(env, hint);
    (*env)->ReleaseStringUTFChars(env, name, utfname);

    return result;
}

/*******************************************************************************
             Functions called by SDL into Java
*******************************************************************************/

static int s_active = 0;
struct LocalReferenceHolder
{
    JNIEnv *m_env;
    const char *m_func;
};

static struct LocalReferenceHolder LocalReferenceHolder_Setup(const char *func)
{
    struct LocalReferenceHolder refholder;
    refholder.m_env = NULL;
    refholder.m_func = func;
#ifdef DEBUG_JNI
    SDL_Log("Entering function %s", func);
#endif
    return refholder;
}

static SDL_bool LocalReferenceHolder_Init(struct LocalReferenceHolder *refholder, JNIEnv *env)
{
    const int capacity = 16;
    if ((*env)->PushLocalFrame(env, capacity) < 0) {
        SDL_SetError("Failed to allocate enough JVM local references");
        return SDL_FALSE;
    }
    ++s_active;
    refholder->m_env = env;
    return SDL_TRUE;
}

static void LocalReferenceHolder_Cleanup(struct LocalReferenceHolder *refholder)
{
#ifdef DEBUG_JNI
    SDL_Log("Leaving function %s", refholder->m_func);
#endif
    if (refholder->m_env) {
        JNIEnv* env = refholder->m_env;
        (*env)->PopLocalFrame(env, NULL);
        --s_active;
    }
}

static SDL_bool LocalReferenceHolder_IsActive(void)
{
    return s_active > 0;
}

ANativeWindow* Android_JNI_GetNativeWindow(void)
{
    ANativeWindow* anw;
    jobject s;
    JNIEnv *env = Android_JNI_GetEnv();

    s = (*env)->CallStaticObjectMethod(env, mActivityClass, midGetNativeSurface);
    anw = ANativeWindow_fromSurface(env, s);
    (*env)->DeleteLocalRef(env, s);
  
    return anw;
}

void Android_JNI_SwapWindow(void)
{
    JNIEnv *mEnv = Android_JNI_GetEnv();
    (*mEnv)->CallStaticVoidMethod(mEnv, mActivityClass, midFlipBuffers);
}

void Android_JNI_SetActivityTitle(const char *title)
{
    jmethodID mid;
    JNIEnv *mEnv = Android_JNI_GetEnv();
    mid = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,"setActivityTitle","(Ljava/lang/String;)Z");
    if (mid) {
        jstring jtitle = (jstring)((*mEnv)->NewStringUTF(mEnv, title));
        (*mEnv)->CallStaticBooleanMethod(mEnv, mActivityClass, mid, jtitle);
        (*mEnv)->DeleteLocalRef(mEnv, jtitle);
    }
}

SDL_bool Android_JNI_GetAccelerometerValues(float values[3])
{
    int i;
    SDL_bool retval = SDL_FALSE;

    if (bHasNewData) {
        for (i = 0; i < 3; ++i) {
            values[i] = fLastAccelerometer[i];
        }
        bHasNewData = SDL_FALSE;
        retval = SDL_TRUE;
    }

    return retval;
}

static void Android_JNI_ThreadDestroyed(void* value)
{
    /* The thread is being destroyed, detach it from the Java VM and set the mThreadKey value to NULL as required */
    JNIEnv *env = (JNIEnv*) value;
    if (env != NULL) {
        (*mJavaVM)->DetachCurrentThread(mJavaVM);
        pthread_setspecific(mThreadKey, NULL);
    }
}

JNIEnv* Android_JNI_GetEnv(void)
{
    /* From http://developer.android.com/guide/practices/jni.html
     * All threads are Linux threads, scheduled by the kernel.
     * They're usually started from managed code (using Thread.start), but they can also be created elsewhere and then
     * attached to the JavaVM. For example, a thread started with pthread_create can be attached with the
     * JNI AttachCurrentThread or AttachCurrentThreadAsDaemon functions. Until a thread is attached, it has no JNIEnv,
     * and cannot make JNI calls.
     * Attaching a natively-created thread causes a java.lang.Thread object to be constructed and added to the "main"
     * ThreadGroup, making it visible to the debugger. Calling AttachCurrentThread on an already-attached thread
     * is a no-op.
     * Note: You can call this function any number of times for the same thread, there's no harm in it
     */

    JNIEnv *env;
    int status = (*mJavaVM)->AttachCurrentThread(mJavaVM, &env, NULL);
    if(status < 0) {
        LOGE("failed to attach current thread");
        return 0;
    }

    /* From http://developer.android.com/guide/practices/jni.html
     * Threads attached through JNI must call DetachCurrentThread before they exit. If coding this directly is awkward,
     * in Android 2.0 (Eclair) and higher you can use pthread_key_create to define a destructor function that will be
     * called before the thread exits, and call DetachCurrentThread from there. (Use that key with pthread_setspecific
     * to store the JNIEnv in thread-local-storage; that way it'll be passed into your destructor as the argument.)
     * Note: The destructor is not called unless the stored value is != NULL
     * Note: You can call this function any number of times for the same thread, there's no harm in it
     *       (except for some lost CPU cycles)
     */
    pthread_setspecific(mThreadKey, (void*) env);

    return env;
}

int Android_JNI_SetupThread(void)
{
    Android_JNI_GetEnv();
    return 1;
}

/*
 * Audio support
 */
static jboolean audioBuffer16Bit = JNI_FALSE;
static jobject audioBuffer = NULL;
static void* audioBufferPinned = NULL;

int Android_JNI_OpenAudioDevice(int sampleRate, int is16Bit, int channelCount, int desiredBufferFrames)
{
    jboolean audioBufferStereo;
    int audioBufferFrames;

    JNIEnv *env = Android_JNI_GetEnv();

    if (!env) {
        LOGE("callback_handler: failed to attach current thread");
    }
    Android_JNI_SetupThread();

    __android_log_print(ANDROID_LOG_VERBOSE, "SDL", "SDL audio: opening device");
    audioBuffer16Bit = is16Bit;
    audioBufferStereo = channelCount > 1;

    if ((*env)->CallStaticIntMethod(env, mActivityClass, midAudioInit, sampleRate, audioBuffer16Bit, audioBufferStereo, desiredBufferFrames) != 0) {
        /* Error during audio initialization */
        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: error on AudioTrack initialization!");
        return 0;
    }

    /* Allocating the audio buffer from the Java side and passing it as the return value for audioInit no longer works on
     * Android >= 4.2 due to a "stale global reference" error. So now we allocate this buffer directly from this side. */

    if (is16Bit) {
        jshortArray audioBufferLocal = (*env)->NewShortArray(env, desiredBufferFrames * (audioBufferStereo ? 2 : 1));
        if (audioBufferLocal) {
            audioBuffer = (*env)->NewGlobalRef(env, audioBufferLocal);
            (*env)->DeleteLocalRef(env, audioBufferLocal);
        }
    }
    else {
        jbyteArray audioBufferLocal = (*env)->NewByteArray(env, desiredBufferFrames * (audioBufferStereo ? 2 : 1));
        if (audioBufferLocal) {
            audioBuffer = (*env)->NewGlobalRef(env, audioBufferLocal);
            (*env)->DeleteLocalRef(env, audioBufferLocal);
        }
    }

    if (audioBuffer == NULL) {
        __android_log_print(ANDROID_LOG_WARN, "SDL", "SDL audio: could not allocate an audio buffer!");
        return 0;
    }

    jboolean isCopy = JNI_FALSE;
    if (audioBuffer16Bit) {
        audioBufferPinned = (*env)->GetShortArrayElements(env, (jshortArray)audioBuffer, &isCopy);
        audioBufferFrames = (*env)->GetArrayLength(env, (jshortArray)audioBuffer);
    } else {
        audioBufferPinned = (*env)->GetByteArrayElements(env, (jbyteArray)audioBuffer, &isCopy);
        audioBufferFrames = (*env)->GetArrayLength(env, (jbyteArray)audioBuffer);
    }
    if (audioBufferStereo) {
        audioBufferFrames /= 2;
    }

    return audioBufferFrames;
}

void * Android_JNI_GetAudioBuffer(void)
{
    return audioBufferPinned;
}

void Android_JNI_WriteAudioBuffer(void)
{
    JNIEnv *mAudioEnv = Android_JNI_GetEnv();

    if (audioBuffer16Bit) {
        (*mAudioEnv)->ReleaseShortArrayElements(mAudioEnv, (jshortArray)audioBuffer, (jshort *)audioBufferPinned, JNI_COMMIT);
        (*mAudioEnv)->CallStaticVoidMethod(mAudioEnv, mActivityClass, midAudioWriteShortBuffer, (jshortArray)audioBuffer);
    } else {
        (*mAudioEnv)->ReleaseByteArrayElements(mAudioEnv, (jbyteArray)audioBuffer, (jbyte *)audioBufferPinned, JNI_COMMIT);
        (*mAudioEnv)->CallStaticVoidMethod(mAudioEnv, mActivityClass, midAudioWriteByteBuffer, (jbyteArray)audioBuffer);
    }

    /* JNI_COMMIT means the changes are committed to the VM but the buffer remains pinned */
}

void Android_JNI_CloseAudioDevice(void)
{
    JNIEnv *env = Android_JNI_GetEnv();

    (*env)->CallStaticVoidMethod(env, mActivityClass, midAudioQuit);

    if (audioBuffer) {
        (*env)->DeleteGlobalRef(env, audioBuffer);
        audioBuffer = NULL;
        audioBufferPinned = NULL;
    }
}

/* Test for an exception and call SDL_SetError with its detail if one occurs */
/* If the parameter silent is truthy then SDL_SetError() will not be called. */
static SDL_bool Android_JNI_ExceptionOccurred(SDL_bool silent)
{
    SDL_assert(LocalReferenceHolder_IsActive());
    JNIEnv *mEnv = Android_JNI_GetEnv();

    jthrowable exception = (*mEnv)->ExceptionOccurred(mEnv);
    if (exception != NULL) {
        jmethodID mid;

        /* Until this happens most JNI operations have undefined behaviour */
        (*mEnv)->ExceptionClear(mEnv);

        if (!silent) {
            jclass exceptionClass = (*mEnv)->GetObjectClass(mEnv, exception);
            jclass classClass = (*mEnv)->FindClass(mEnv, "java/lang/Class");

            mid = (*mEnv)->GetMethodID(mEnv, classClass, "getName", "()Ljava/lang/String;");
            jstring exceptionName = (jstring)(*mEnv)->CallObjectMethod(mEnv, exceptionClass, mid);
            const char* exceptionNameUTF8 = (*mEnv)->GetStringUTFChars(mEnv, exceptionName, 0);

            mid = (*mEnv)->GetMethodID(mEnv, exceptionClass, "getMessage", "()Ljava/lang/String;");
            jstring exceptionMessage = (jstring)(*mEnv)->CallObjectMethod(mEnv, exception, mid);

            if (exceptionMessage != NULL) {
                const char* exceptionMessageUTF8 = (*mEnv)->GetStringUTFChars(mEnv, exceptionMessage, 0);
                SDL_SetError("%s: %s", exceptionNameUTF8, exceptionMessageUTF8);
                (*mEnv)->ReleaseStringUTFChars(mEnv, exceptionMessage, exceptionMessageUTF8);
            } else {
                SDL_SetError("%s", exceptionNameUTF8);
            }

            (*mEnv)->ReleaseStringUTFChars(mEnv, exceptionName, exceptionNameUTF8);
        }

        return SDL_TRUE;
    }

    return SDL_FALSE;
}

static int Internal_Android_JNI_FileOpen(SDL_RWops* ctx)
{
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);

    int result = 0;

    jmethodID mid;
    jobject context;
    jobject assetManager;
    jobject inputStream;
    jclass channels;
    jobject readableByteChannel;
    jstring fileNameJString;
    jobject fd;
    jclass fdCls;
    jfieldID descriptor;

    JNIEnv *mEnv = Android_JNI_GetEnv();
    if (!LocalReferenceHolder_Init(&refs, mEnv)) {
        goto failure;
    }

    fileNameJString = (jstring)ctx->hidden.androidio.fileNameRef;
    ctx->hidden.androidio.position = 0;

    /* context = SDLActivity.getContext(); */
    mid = (*mEnv)->GetStaticMethodID(mEnv, mActivityClass,
            "getContext","()Landroid/content/Context;");
    context = (*mEnv)->CallStaticObjectMethod(mEnv, mActivityClass, mid);


    /* assetManager = context.getAssets(); */
    mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, context),
            "getAssets", "()Landroid/content/res/AssetManager;");
    assetManager = (*mEnv)->CallObjectMethod(mEnv, context, mid);

    /* First let's try opening the file to obtain an AssetFileDescriptor.
    * This method reads the files directly from the APKs using standard *nix calls
    */
    mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, assetManager), "openFd", "(Ljava/lang/String;)Landroid/content/res/AssetFileDescriptor;");
    inputStream = (*mEnv)->CallObjectMethod(mEnv, assetManager, mid, fileNameJString);
    if (Android_JNI_ExceptionOccurred(SDL_TRUE)) {
        goto fallback;
    }

    mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, inputStream), "getStartOffset", "()J");
    ctx->hidden.androidio.offset = (*mEnv)->CallLongMethod(mEnv, inputStream, mid);
    if (Android_JNI_ExceptionOccurred(SDL_TRUE)) {
        goto fallback;
    }

    mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, inputStream), "getDeclaredLength", "()J");
    ctx->hidden.androidio.size = (*mEnv)->CallLongMethod(mEnv, inputStream, mid);
    if (Android_JNI_ExceptionOccurred(SDL_TRUE)) {
        goto fallback;
    }

    mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, inputStream), "getFileDescriptor", "()Ljava/io/FileDescriptor;");
    fd = (*mEnv)->CallObjectMethod(mEnv, inputStream, mid);
    fdCls = (*mEnv)->GetObjectClass(mEnv, fd);
    descriptor = (*mEnv)->GetFieldID(mEnv, fdCls, "descriptor", "I");
    ctx->hidden.androidio.fd = (*mEnv)->GetIntField(mEnv, fd, descriptor);
    ctx->hidden.androidio.assetFileDescriptorRef = (*mEnv)->NewGlobalRef(mEnv, inputStream);

    /* Seek to the correct offset in the file. */
    lseek(ctx->hidden.androidio.fd, (off_t)ctx->hidden.androidio.offset, SEEK_SET);

    if (0) {
fallback:
        /* Disabled log message because of spam on the Nexus 7 */
        /* __android_log_print(ANDROID_LOG_DEBUG, "SDL", "Falling back to legacy InputStream method for opening file"); */

        /* Try the old method using InputStream */
        ctx->hidden.androidio.assetFileDescriptorRef = NULL;

        /* inputStream = assetManager.open(<filename>); */
        mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, assetManager),
                "open", "(Ljava/lang/String;I)Ljava/io/InputStream;");
        inputStream = (*mEnv)->CallObjectMethod(mEnv, assetManager, mid, fileNameJString, 1 /* ACCESS_RANDOM */);
        if (Android_JNI_ExceptionOccurred(SDL_FALSE)) {
            /* Try fallback to APK expansion files */
            mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, context),
                "openAPKExpansionInputStream", "(Ljava/lang/String;)Ljava/io/InputStream;");
            if (!mid) {
                SDL_SetError("No openAPKExpansionInputStream() in Java class");
                goto failure; /* Java class is missing the required method */
            }
            inputStream = (*mEnv)->CallObjectMethod(mEnv, context, mid, fileNameJString);

            /* Exception is checked first because it always needs to be cleared.
             * If no exception occurred then the last SDL error message is kept.
             */
            if (Android_JNI_ExceptionOccurred(SDL_FALSE) || !inputStream) {
                goto failure;
            }
        }

        ctx->hidden.androidio.inputStreamRef = (*mEnv)->NewGlobalRef(mEnv, inputStream);

        /* Despite all the visible documentation on [Asset]InputStream claiming
         * that the .available() method is not guaranteed to return the entire file
         * size, comments in <sdk>/samples/<ver>/ApiDemos/src/com/example/ ...
         * android/apis/content/ReadAsset.java imply that Android's
         * AssetInputStream.available() /will/ always return the total file size
        */
        
        /* size = inputStream.available(); */
        mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, inputStream),
                "available", "()I");
        ctx->hidden.androidio.size = (long)(*mEnv)->CallIntMethod(mEnv, inputStream, mid);
        if (Android_JNI_ExceptionOccurred(SDL_FALSE)) {
            goto failure;
        }

        /* readableByteChannel = Channels.newChannel(inputStream); */
        channels = (*mEnv)->FindClass(mEnv, "java/nio/channels/Channels");
        mid = (*mEnv)->GetStaticMethodID(mEnv, channels,
                "newChannel",
                "(Ljava/io/InputStream;)Ljava/nio/channels/ReadableByteChannel;");
        readableByteChannel = (*mEnv)->CallStaticObjectMethod(
                mEnv, channels, mid, inputStream);
        if (Android_JNI_ExceptionOccurred(SDL_FALSE)) {
            goto failure;
        }

        ctx->hidden.androidio.readableByteChannelRef =
            (*mEnv)->NewGlobalRef(mEnv, readableByteChannel);

        /* Store .read id for reading purposes */
        mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, readableByteChannel),
                "read", "(Ljava/nio/ByteBuffer;)I");
        ctx->hidden.androidio.readMethod = mid;
    }

    if (0) {
failure:
        result = -1;

        (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.fileNameRef);

        if(ctx->hidden.androidio.inputStreamRef != NULL) {
            (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.inputStreamRef);
        }

        if(ctx->hidden.androidio.readableByteChannelRef != NULL) {
            (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.readableByteChannelRef);
        }

        if(ctx->hidden.androidio.assetFileDescriptorRef != NULL) {
            (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.assetFileDescriptorRef);
        }

    }
    
    LocalReferenceHolder_Cleanup(&refs);
    return result;
}

int Android_JNI_FileOpen(SDL_RWops* ctx,
        const char* fileName, const char* mode)
{
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);
    JNIEnv *mEnv = Android_JNI_GetEnv();
    int retval;

    if (!LocalReferenceHolder_Init(&refs, mEnv)) {
        LocalReferenceHolder_Cleanup(&refs);        
        return -1;
    }

    if (!ctx) {
        LocalReferenceHolder_Cleanup(&refs);
        return -1;
    }

    jstring fileNameJString = (*mEnv)->NewStringUTF(mEnv, fileName);
    ctx->hidden.androidio.fileNameRef = (*mEnv)->NewGlobalRef(mEnv, fileNameJString);
    ctx->hidden.androidio.inputStreamRef = NULL;
    ctx->hidden.androidio.readableByteChannelRef = NULL;
    ctx->hidden.androidio.readMethod = NULL;
    ctx->hidden.androidio.assetFileDescriptorRef = NULL;

    retval = Internal_Android_JNI_FileOpen(ctx);
    LocalReferenceHolder_Cleanup(&refs);
    return retval;
}

size_t Android_JNI_FileRead(SDL_RWops* ctx, void* buffer,
        size_t size, size_t maxnum)
{
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);

    if (ctx->hidden.androidio.assetFileDescriptorRef) {
        size_t bytesMax = size * maxnum;
        if (ctx->hidden.androidio.size != -1 /* UNKNOWN_LENGTH */ && ctx->hidden.androidio.position + bytesMax > ctx->hidden.androidio.size) {
            bytesMax = ctx->hidden.androidio.size - ctx->hidden.androidio.position;
        }
        size_t result = read(ctx->hidden.androidio.fd, buffer, bytesMax );
        if (result > 0) {
            ctx->hidden.androidio.position += result;
            LocalReferenceHolder_Cleanup(&refs);
            return result / size;
        }
        LocalReferenceHolder_Cleanup(&refs);
        return 0;
    } else {
        jlong bytesRemaining = (jlong) (size * maxnum);
        jlong bytesMax = (jlong) (ctx->hidden.androidio.size -  ctx->hidden.androidio.position);
        int bytesRead = 0;

        /* Don't read more bytes than those that remain in the file, otherwise we get an exception */
        if (bytesRemaining >  bytesMax) bytesRemaining = bytesMax;

        JNIEnv *mEnv = Android_JNI_GetEnv();
        if (!LocalReferenceHolder_Init(&refs, mEnv)) {
            LocalReferenceHolder_Cleanup(&refs);            
            return 0;
        }

        jobject readableByteChannel = (jobject)ctx->hidden.androidio.readableByteChannelRef;
        jmethodID readMethod = (jmethodID)ctx->hidden.androidio.readMethod;
        jobject byteBuffer = (*mEnv)->NewDirectByteBuffer(mEnv, buffer, bytesRemaining);

        while (bytesRemaining > 0) {
            /* result = readableByteChannel.read(...); */
            int result = (*mEnv)->CallIntMethod(mEnv, readableByteChannel, readMethod, byteBuffer);

            if (Android_JNI_ExceptionOccurred(SDL_FALSE)) {
                LocalReferenceHolder_Cleanup(&refs);            
                return 0;
            }

            if (result < 0) {
                break;
            }

            bytesRemaining -= result;
            bytesRead += result;
            ctx->hidden.androidio.position += result;
        }
        LocalReferenceHolder_Cleanup(&refs);                    
        return bytesRead / size;
    }
}

size_t Android_JNI_FileWrite(SDL_RWops* ctx, const void* buffer,
        size_t size, size_t num)
{
    SDL_SetError("Cannot write to Android package filesystem");
    return 0;
}

static int Internal_Android_JNI_FileClose(SDL_RWops* ctx, SDL_bool release)
{
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);

    int result = 0;
    JNIEnv *mEnv = Android_JNI_GetEnv();

    if (!LocalReferenceHolder_Init(&refs, mEnv)) {
        LocalReferenceHolder_Cleanup(&refs);
        return SDL_SetError("Failed to allocate enough JVM local references");
    }

    if (ctx) {
        if (release) {
            (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.fileNameRef);
        }

        if (ctx->hidden.androidio.assetFileDescriptorRef) {
            jobject inputStream = (jobject)ctx->hidden.androidio.assetFileDescriptorRef;
            jmethodID mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, inputStream),
                    "close", "()V");
            (*mEnv)->CallVoidMethod(mEnv, inputStream, mid);
            (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.assetFileDescriptorRef);
            if (Android_JNI_ExceptionOccurred(SDL_FALSE)) {
                result = -1;
            }
        }
        else {
            jobject inputStream = (jobject)ctx->hidden.androidio.inputStreamRef;

            /* inputStream.close(); */
            jmethodID mid = (*mEnv)->GetMethodID(mEnv, (*mEnv)->GetObjectClass(mEnv, inputStream),
                    "close", "()V");
            (*mEnv)->CallVoidMethod(mEnv, inputStream, mid);
            (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.inputStreamRef);
            (*mEnv)->DeleteGlobalRef(mEnv, (jobject)ctx->hidden.androidio.readableByteChannelRef);
            if (Android_JNI_ExceptionOccurred(SDL_FALSE)) {
                result = -1;
            }
        }

        if (release) {
            SDL_FreeRW(ctx);
        }
    }

    LocalReferenceHolder_Cleanup(&refs);
    return result;
}


Sint64 Android_JNI_FileSize(SDL_RWops* ctx)
{
    return ctx->hidden.androidio.size;
}

Sint64 Android_JNI_FileSeek(SDL_RWops* ctx, Sint64 offset, int whence)
{
    if (ctx->hidden.androidio.assetFileDescriptorRef) {
        switch (whence) {
            case RW_SEEK_SET:
                if (ctx->hidden.androidio.size != -1 /* UNKNOWN_LENGTH */ && offset > ctx->hidden.androidio.size) offset = ctx->hidden.androidio.size;
                offset += ctx->hidden.androidio.offset;
                break;
            case RW_SEEK_CUR:
                offset += ctx->hidden.androidio.position;
                if (ctx->hidden.androidio.size != -1 /* UNKNOWN_LENGTH */ && offset > ctx->hidden.androidio.size) offset = ctx->hidden.androidio.size;
                offset += ctx->hidden.androidio.offset;
                break;
            case RW_SEEK_END:
                offset = ctx->hidden.androidio.offset + ctx->hidden.androidio.size + offset;
                break;
            default:
                return SDL_SetError("Unknown value for 'whence'");
        }
        whence = SEEK_SET;

        off_t ret = lseek(ctx->hidden.androidio.fd, (off_t)offset, SEEK_SET);
        if (ret == -1) return -1;
        ctx->hidden.androidio.position = ret - ctx->hidden.androidio.offset;
    } else {
        Sint64 newPosition;

        switch (whence) {
            case RW_SEEK_SET:
                newPosition = offset;
                break;
            case RW_SEEK_CUR:
                newPosition = ctx->hidden.androidio.position + offset;
                break;
            case RW_SEEK_END:
                newPosition = ctx->hidden.androidio.size + offset;
                break;
            default:
                return SDL_SetError("Unknown value for 'whence'");
        }

        /* Validate the new position */
        if (newPosition < 0) {
            return SDL_Error(SDL_EFSEEK);
        }
        if (newPosition > ctx->hidden.androidio.size) {
            newPosition = ctx->hidden.androidio.size;
        }

        Sint64 movement = newPosition - ctx->hidden.androidio.position;
        if (movement > 0) {
            unsigned char buffer[4096];

            /* The easy case where we're seeking forwards */
            while (movement > 0) {
                Sint64 amount = sizeof (buffer);
                if (amount > movement) {
                    amount = movement;
                }
                size_t result = Android_JNI_FileRead(ctx, buffer, 1, amount);
                if (result <= 0) {
                    /* Failed to read/skip the required amount, so fail */
                    return -1;
                }

                movement -= result;
            }

        } else if (movement < 0) {
            /* We can't seek backwards so we have to reopen the file and seek */
            /* forwards which obviously isn't very efficient */
            Internal_Android_JNI_FileClose(ctx, SDL_FALSE);
            Internal_Android_JNI_FileOpen(ctx);
            Android_JNI_FileSeek(ctx, newPosition, RW_SEEK_SET);
        }
    }

    return ctx->hidden.androidio.position;

}

int Android_JNI_FileClose(SDL_RWops* ctx)
{
    return Internal_Android_JNI_FileClose(ctx, SDL_TRUE);
}

/* returns a new global reference which needs to be released later */
static jobject Android_JNI_GetSystemServiceObject(const char* name)
{
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);
    JNIEnv* env = Android_JNI_GetEnv();
    jobject retval = NULL;

    if (!LocalReferenceHolder_Init(&refs, env)) {
        LocalReferenceHolder_Cleanup(&refs);
        return NULL;
    }

    jstring service = (*env)->NewStringUTF(env, name);

    jmethodID mid;

    mid = (*env)->GetStaticMethodID(env, mActivityClass, "getContext", "()Landroid/content/Context;");
    jobject context = (*env)->CallStaticObjectMethod(env, mActivityClass, mid);

    mid = (*env)->GetMethodID(env, mActivityClass, "getSystemServiceFromUiThread", "(Ljava/lang/String;)Ljava/lang/Object;");
    jobject manager = (*env)->CallObjectMethod(env, context, mid, service);

    (*env)->DeleteLocalRef(env, service);

    retval = manager ? (*env)->NewGlobalRef(env, manager) : NULL;
    LocalReferenceHolder_Cleanup(&refs);
    return retval;
}

#define SETUP_CLIPBOARD(error) \
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__); \
    JNIEnv* env = Android_JNI_GetEnv(); \
    if (!LocalReferenceHolder_Init(&refs, env)) { \
        LocalReferenceHolder_Cleanup(&refs); \
        return error; \
    } \
    jobject clipboard = Android_JNI_GetSystemServiceObject("clipboard"); \
    if (!clipboard) { \
        LocalReferenceHolder_Cleanup(&refs); \
        return error; \
    }

#define CLEANUP_CLIPBOARD() \
    LocalReferenceHolder_Cleanup(&refs);

int Android_JNI_SetClipboardText(const char* text)
{
    SETUP_CLIPBOARD(-1)

    jmethodID mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, clipboard), "setText", "(Ljava/lang/CharSequence;)V");
    jstring string = (*env)->NewStringUTF(env, text);
    (*env)->CallVoidMethod(env, clipboard, mid, string);
    (*env)->DeleteGlobalRef(env, clipboard);
    (*env)->DeleteLocalRef(env, string);

    CLEANUP_CLIPBOARD();

    return 0;
}

char* Android_JNI_GetClipboardText(void)
{
    SETUP_CLIPBOARD(SDL_strdup(""))

    jmethodID mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, clipboard), "getText", "()Ljava/lang/CharSequence;");
    jobject sequence = (*env)->CallObjectMethod(env, clipboard, mid);
    (*env)->DeleteGlobalRef(env, clipboard);
    if (sequence) {
        mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, sequence), "toString", "()Ljava/lang/String;");
        jstring string = (jstring)((*env)->CallObjectMethod(env, sequence, mid));
        const char* utf = (*env)->GetStringUTFChars(env, string, 0);
        if (utf) {
            char* text = SDL_strdup(utf);
            (*env)->ReleaseStringUTFChars(env, string, utf);

            CLEANUP_CLIPBOARD();

            return text;
        }
    }

    CLEANUP_CLIPBOARD();    

    return SDL_strdup("");
}

SDL_bool Android_JNI_HasClipboardText(void)
{
    SETUP_CLIPBOARD(SDL_FALSE)

    jmethodID mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, clipboard), "hasText", "()Z");
    jboolean has = (*env)->CallBooleanMethod(env, clipboard, mid);
    (*env)->DeleteGlobalRef(env, clipboard);

    CLEANUP_CLIPBOARD();
    
    return has ? SDL_TRUE : SDL_FALSE;
}


/* returns 0 on success or -1 on error (others undefined then)
 * returns truthy or falsy value in plugged, charged and battery
 * returns the value in seconds and percent or -1 if not available
 */
int Android_JNI_GetPowerInfo(int* plugged, int* charged, int* battery, int* seconds, int* percent)
{
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);
    JNIEnv* env = Android_JNI_GetEnv();
    if (!LocalReferenceHolder_Init(&refs, env)) {
        LocalReferenceHolder_Cleanup(&refs);
        return -1;
    }

    jmethodID mid;

    mid = (*env)->GetStaticMethodID(env, mActivityClass, "getContext", "()Landroid/content/Context;");
    jobject context = (*env)->CallStaticObjectMethod(env, mActivityClass, mid);

    jstring action = (*env)->NewStringUTF(env, "android.intent.action.BATTERY_CHANGED");

    jclass cls = (*env)->FindClass(env, "android/content/IntentFilter");

    mid = (*env)->GetMethodID(env, cls, "<init>", "(Ljava/lang/String;)V");
    jobject filter = (*env)->NewObject(env, cls, mid, action);

    (*env)->DeleteLocalRef(env, action);

    mid = (*env)->GetMethodID(env, mActivityClass, "registerReceiver", "(Landroid/content/BroadcastReceiver;Landroid/content/IntentFilter;)Landroid/content/Intent;");
    jobject intent = (*env)->CallObjectMethod(env, context, mid, NULL, filter);

    (*env)->DeleteLocalRef(env, filter);

    cls = (*env)->GetObjectClass(env, intent);

    jstring iname;
    jmethodID imid = (*env)->GetMethodID(env, cls, "getIntExtra", "(Ljava/lang/String;I)I");

#define GET_INT_EXTRA(var, key) \
    iname = (*env)->NewStringUTF(env, key); \
    int var = (*env)->CallIntMethod(env, intent, imid, iname, -1); \
    (*env)->DeleteLocalRef(env, iname);

    jstring bname;
    jmethodID bmid = (*env)->GetMethodID(env, cls, "getBooleanExtra", "(Ljava/lang/String;Z)Z");

#define GET_BOOL_EXTRA(var, key) \
    bname = (*env)->NewStringUTF(env, key); \
    int var = (*env)->CallBooleanMethod(env, intent, bmid, bname, JNI_FALSE); \
    (*env)->DeleteLocalRef(env, bname);

    if (plugged) {
        GET_INT_EXTRA(plug, "plugged") /* == BatteryManager.EXTRA_PLUGGED (API 5) */
        if (plug == -1) {
            LocalReferenceHolder_Cleanup(&refs);
            return -1;
        }
        /* 1 == BatteryManager.BATTERY_PLUGGED_AC */
        /* 2 == BatteryManager.BATTERY_PLUGGED_USB */
        *plugged = (0 < plug) ? 1 : 0;
    }

    if (charged) {
        GET_INT_EXTRA(status, "status") /* == BatteryManager.EXTRA_STATUS (API 5) */
        if (status == -1) {
            LocalReferenceHolder_Cleanup(&refs);
            return -1;
        }
        /* 5 == BatteryManager.BATTERY_STATUS_FULL */
        *charged = (status == 5) ? 1 : 0;
    }

    if (battery) {
        GET_BOOL_EXTRA(present, "present") /* == BatteryManager.EXTRA_PRESENT (API 5) */
        *battery = present ? 1 : 0;
    }

    if (seconds) {
        *seconds = -1; /* not possible */
    }

    if (percent) {
        GET_INT_EXTRA(level, "level") /* == BatteryManager.EXTRA_LEVEL (API 5) */
        GET_INT_EXTRA(scale, "scale") /* == BatteryManager.EXTRA_SCALE (API 5) */
        if ((level == -1) || (scale == -1)) {
            LocalReferenceHolder_Cleanup(&refs);
            return -1;
        }
        *percent = level * 100 / scale;
    }

    (*env)->DeleteLocalRef(env, intent);

    LocalReferenceHolder_Cleanup(&refs);
    return 0;
}

/* returns number of found touch devices as return value and ids in parameter ids */
int Android_JNI_GetTouchDeviceIds(int **ids) {
    JNIEnv *env = Android_JNI_GetEnv();
    jint sources = 4098; /* == InputDevice.SOURCE_TOUCHSCREEN */
    jmethodID mid = (*env)->GetStaticMethodID(env, mActivityClass, "inputGetInputDeviceIds", "(I)[I");
    jintArray array = (jintArray) (*env)->CallStaticObjectMethod(env, mActivityClass, mid, sources);
    int number = 0;
    *ids = NULL;
    if (array) {
        number = (int) (*env)->GetArrayLength(env, array);
        if (0 < number) {
            jint* elements = (*env)->GetIntArrayElements(env, array, NULL);
            if (elements) {
                int i;
                *ids = SDL_malloc(number * sizeof (**ids));
                for (i = 0; i < number; ++i) { /* not assuming sizeof (jint) == sizeof (int) */
                    (*ids)[i] = elements[i];
                }
                (*env)->ReleaseIntArrayElements(env, array, elements, JNI_ABORT);
            }
        }
        (*env)->DeleteLocalRef(env, array);
    }
    return number;
}

void Android_JNI_PollInputDevices(void)
{
    JNIEnv *env = Android_JNI_GetEnv();
    (*env)->CallStaticVoidMethod(env, mActivityClass, midPollInputDevices);    
}

/* See SDLActivity.java for constants. */
#define COMMAND_SET_KEEP_SCREEN_ON    5

/* sends message to be handled on the UI event dispatch thread */
int Android_JNI_SendMessage(int command, int param)
{
    JNIEnv *env = Android_JNI_GetEnv();
    if (!env) {
        return -1;
    }
    jmethodID mid = (*env)->GetStaticMethodID(env, mActivityClass, "sendMessage", "(II)Z");
    if (!mid) {
        return -1;
    }
    jboolean success = (*env)->CallStaticBooleanMethod(env, mActivityClass, mid, command, param);
    return success ? 0 : -1;
}

void Android_JNI_SuspendScreenSaver(SDL_bool suspend)
{
    Android_JNI_SendMessage(COMMAND_SET_KEEP_SCREEN_ON, (suspend == SDL_FALSE) ? 0 : 1);
}

void Android_JNI_ShowTextInput(SDL_Rect *inputRect)
{
    JNIEnv *env = Android_JNI_GetEnv();
    if (!env) {
        return;
    }

    jmethodID mid = (*env)->GetStaticMethodID(env, mActivityClass, "showTextInput", "(IIII)Z");
    if (!mid) {
        return;
    }
    (*env)->CallStaticBooleanMethod(env, mActivityClass, mid,
                               inputRect->x,
                               inputRect->y,
                               inputRect->w,
                               inputRect->h );
}

void Android_JNI_HideTextInput(void)
{
    /* has to match Activity constant */
    const int COMMAND_TEXTEDIT_HIDE = 3;
    Android_JNI_SendMessage(COMMAND_TEXTEDIT_HIDE, 0);
}

int Android_JNI_ShowMessageBox(const SDL_MessageBoxData *messageboxdata, int *buttonid)
{
    JNIEnv *env;
    jclass clazz;
    jmethodID mid;
    jobject context;
    jstring title;
    jstring message;
    jintArray button_flags;
    jintArray button_ids;
    jobjectArray button_texts;
    jintArray colors;
    jobject text;
    jint temp;
    int i;

    env = Android_JNI_GetEnv();

    /* convert parameters */

    clazz = (*env)->FindClass(env, "java/lang/String");

    title = (*env)->NewStringUTF(env, messageboxdata->title);
    message = (*env)->NewStringUTF(env, messageboxdata->message);

    button_flags = (*env)->NewIntArray(env, messageboxdata->numbuttons);
    button_ids = (*env)->NewIntArray(env, messageboxdata->numbuttons);
    button_texts = (*env)->NewObjectArray(env, messageboxdata->numbuttons,
        clazz, NULL);
    for (i = 0; i < messageboxdata->numbuttons; ++i) {
        temp = messageboxdata->buttons[i].flags;
        (*env)->SetIntArrayRegion(env, button_flags, i, 1, &temp);
        temp = messageboxdata->buttons[i].buttonid;
        (*env)->SetIntArrayRegion(env, button_ids, i, 1, &temp);
        text = (*env)->NewStringUTF(env, messageboxdata->buttons[i].text);
        (*env)->SetObjectArrayElement(env, button_texts, i, text);
        (*env)->DeleteLocalRef(env, text);
    }

    if (messageboxdata->colorScheme) {
        colors = (*env)->NewIntArray(env, SDL_MESSAGEBOX_COLOR_MAX);
        for (i = 0; i < SDL_MESSAGEBOX_COLOR_MAX; ++i) {
            temp = (0xFF << 24) |
                   (messageboxdata->colorScheme->colors[i].r << 16) |
                   (messageboxdata->colorScheme->colors[i].g << 8) |
                   (messageboxdata->colorScheme->colors[i].b << 0);
            (*env)->SetIntArrayRegion(env, colors, i, 1, &temp);
        }
    } else {
        colors = NULL;
    }

    (*env)->DeleteLocalRef(env, clazz);

    /* call function */

    mid = (*env)->GetStaticMethodID(env, mActivityClass, "getContext","()Landroid/content/Context;");

    context = (*env)->CallStaticObjectMethod(env, mActivityClass, mid);

    clazz = (*env)->GetObjectClass(env, context);

    mid = (*env)->GetMethodID(env, clazz,
        "messageboxShowMessageBox", "(ILjava/lang/String;Ljava/lang/String;[I[I[Ljava/lang/String;[I)I");
    *buttonid = (*env)->CallIntMethod(env, context, mid,
        messageboxdata->flags,
        title,
        message,
        button_flags,
        button_ids,
        button_texts,
        colors);

    (*env)->DeleteLocalRef(env, context);
    (*env)->DeleteLocalRef(env, clazz);

    /* delete parameters */

    (*env)->DeleteLocalRef(env, title);
    (*env)->DeleteLocalRef(env, message);
    (*env)->DeleteLocalRef(env, button_flags);
    (*env)->DeleteLocalRef(env, button_ids);
    (*env)->DeleteLocalRef(env, button_texts);
    (*env)->DeleteLocalRef(env, colors);

    return 0;
}

/*
//////////////////////////////////////////////////////////////////////////////
//
// Functions exposed to SDL applications in SDL_system.h
//////////////////////////////////////////////////////////////////////////////
*/

void *SDL_AndroidGetJNIEnv()
{
    return Android_JNI_GetEnv();
}


void *SDL_AndroidGetActivity()
{
    /* See SDL_system.h for caveats on using this function. */

    jmethodID mid;

    JNIEnv *env = Android_JNI_GetEnv();
    if (!env) {
        return NULL;
    }

    /* return SDLActivity.getContext(); */
    mid = (*env)->GetStaticMethodID(env, mActivityClass,
            "getContext","()Landroid/content/Context;");
    return (*env)->CallStaticObjectMethod(env, mActivityClass, mid);
}

const char * SDL_AndroidGetInternalStoragePath()
{
    static char *s_AndroidInternalFilesPath = NULL;

    if (!s_AndroidInternalFilesPath) {
        struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);
        jmethodID mid;
        jobject context;
        jobject fileObject;
        jstring pathString;
        const char *path;

        JNIEnv *env = Android_JNI_GetEnv();
        if (!LocalReferenceHolder_Init(&refs, env)) {
            LocalReferenceHolder_Cleanup(&refs);
            return NULL;
        }

        /* context = SDLActivity.getContext(); */
        mid = (*env)->GetStaticMethodID(env, mActivityClass,
                "getContext","()Landroid/content/Context;");
        context = (*env)->CallStaticObjectMethod(env, mActivityClass, mid);

        /* fileObj = context.getFilesDir(); */
        mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, context),
                "getFilesDir", "()Ljava/io/File;");
        fileObject = (*env)->CallObjectMethod(env, context, mid);
        if (!fileObject) {
            SDL_SetError("Couldn't get internal directory");
            LocalReferenceHolder_Cleanup(&refs);
            return NULL;
        }

        /* path = fileObject.getAbsolutePath(); */
        mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, fileObject),
                "getAbsolutePath", "()Ljava/lang/String;");
        pathString = (jstring)(*env)->CallObjectMethod(env, fileObject, mid);

        path = (*env)->GetStringUTFChars(env, pathString, NULL);
        s_AndroidInternalFilesPath = SDL_strdup(path);
        (*env)->ReleaseStringUTFChars(env, pathString, path);

        LocalReferenceHolder_Cleanup(&refs);
    }
    return s_AndroidInternalFilesPath;
}

int SDL_AndroidGetExternalStorageState()
{
    struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);
    jmethodID mid;
    jclass cls;
    jstring stateString;
    const char *state;
    int stateFlags;

    JNIEnv *env = Android_JNI_GetEnv();
    if (!LocalReferenceHolder_Init(&refs, env)) {
        LocalReferenceHolder_Cleanup(&refs);
        return 0;
    }

    cls = (*env)->FindClass(env, "android/os/Environment");
    mid = (*env)->GetStaticMethodID(env, cls,
            "getExternalStorageState", "()Ljava/lang/String;");
    stateString = (jstring)(*env)->CallStaticObjectMethod(env, cls, mid);

    state = (*env)->GetStringUTFChars(env, stateString, NULL);

    /* Print an info message so people debugging know the storage state */
    __android_log_print(ANDROID_LOG_INFO, "SDL", "external storage state: %s", state);

    if (SDL_strcmp(state, "mounted") == 0) {
        stateFlags = SDL_ANDROID_EXTERNAL_STORAGE_READ |
                     SDL_ANDROID_EXTERNAL_STORAGE_WRITE;
    } else if (SDL_strcmp(state, "mounted_ro") == 0) {
        stateFlags = SDL_ANDROID_EXTERNAL_STORAGE_READ;
    } else {
        stateFlags = 0;
    }
    (*env)->ReleaseStringUTFChars(env, stateString, state);

    LocalReferenceHolder_Cleanup(&refs);
    return stateFlags;
}

const char * SDL_AndroidGetExternalStoragePath()
{
    static char *s_AndroidExternalFilesPath = NULL;

    if (!s_AndroidExternalFilesPath) {
        struct LocalReferenceHolder refs = LocalReferenceHolder_Setup(__FUNCTION__);
        jmethodID mid;
        jobject context;
        jobject fileObject;
        jstring pathString;
        const char *path;

        JNIEnv *env = Android_JNI_GetEnv();
        if (!LocalReferenceHolder_Init(&refs, env)) {
            LocalReferenceHolder_Cleanup(&refs);
            return NULL;
        }

        /* context = SDLActivity.getContext(); */
        mid = (*env)->GetStaticMethodID(env, mActivityClass,
                "getContext","()Landroid/content/Context;");
        context = (*env)->CallStaticObjectMethod(env, mActivityClass, mid);

        /* fileObj = context.getExternalFilesDir(); */
        mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, context),
                "getExternalFilesDir", "(Ljava/lang/String;)Ljava/io/File;");
        fileObject = (*env)->CallObjectMethod(env, context, mid, NULL);
        if (!fileObject) {
            SDL_SetError("Couldn't get external directory");
            LocalReferenceHolder_Cleanup(&refs);
            return NULL;
        }

        /* path = fileObject.getAbsolutePath(); */
        mid = (*env)->GetMethodID(env, (*env)->GetObjectClass(env, fileObject),
                "getAbsolutePath", "()Ljava/lang/String;");
        pathString = (jstring)(*env)->CallObjectMethod(env, fileObject, mid);

        path = (*env)->GetStringUTFChars(env, pathString, NULL);
        s_AndroidExternalFilesPath = SDL_strdup(path);
        (*env)->ReleaseStringUTFChars(env, pathString, path);

        LocalReferenceHolder_Cleanup(&refs);
    }
    return s_AndroidExternalFilesPath;
}

jclass Android_JNI_GetActivityClass(void)
{
    return mActivityClass;
}

#endif /* __ANDROID__ */

/* vi: set ts=4 sw=4 expandtab: */