Method processScrollEvent

src/SFML/Window/Android/WindowImplAndroid.cpp:338–402

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int WindowImplAndroid::processScrollEvent(AInputEvent* inputEvent, ActivityStates& states)
{
    // Prepare the Java virtual machine
    auto jni = Jni::attachCurrentThread(*states.activity);
    if (!jni)
    {
        err() << "Failed to initialize JNI" << std::endl;
        return 0;
    }

    auto& lJNIEnv = jni->getEnv();

    // Retrieve everything we need to create this MotionEvent in Java
    const std::int64_t downTime   = AMotionEvent_getDownTime(inputEvent);
    const std::int64_t eventTime  = AMotionEvent_getEventTime(inputEvent);
    const std::int32_t action     = AMotionEvent_getAction(inputEvent);
    const float        x          = AMotionEvent_getX(inputEvent, 0);
    const float        y          = AMotionEvent_getY(inputEvent, 0);
    const float        pressure   = AMotionEvent_getPressure(inputEvent, 0);
    const float        size       = AMotionEvent_getSize(inputEvent, 0);
    const std::int32_t metaState  = AMotionEvent_getMetaState(inputEvent);
    const float        xPrecision = AMotionEvent_getXPrecision(inputEvent);
    const float        yPrecision = AMotionEvent_getYPrecision(inputEvent);
    const std::int32_t deviceId   = AInputEvent_getDeviceId(inputEvent);
    const std::int32_t edgeFlags  = AMotionEvent_getEdgeFlags(inputEvent);

    // Create the MotionEvent object in Java through its static constructor obtain()
    jclass    classMotionEvent   = lJNIEnv.FindClass("android/view/MotionEvent");
    jmethodID staticMethodObtain = lJNIEnv.GetStaticMethodID(classMotionEvent,
                                                             "obtain",
                                                             "(JJIFFFFIFFII)Landroid/view/MotionEvent;");
    // Note: C standard compatibility, varargs
    //       automatically promote floats to doubles
    //       even though the function signature declares float
    jobject objectMotionEvent = lJNIEnv.CallStaticObjectMethod(classMotionEvent,
                                                               staticMethodObtain,
                                                               downTime,
                                                               eventTime,
                                                               action,
                                                               static_cast<double>(x),
                                                               static_cast<double>(y),
                                                               static_cast<double>(pressure),
                                                               static_cast<double>(size),
                                                               metaState,
                                                               static_cast<double>(xPrecision),
                                                               static_cast<double>(yPrecision),
                                                               deviceId,
                                                               edgeFlags);

    // Call its getAxisValue() method to get the delta value of our wheel move event
    jmethodID    methodGetAxisValue = lJNIEnv.GetMethodID(classMotionEvent, "getAxisValue", "(I)F");
    const jfloat delta              = lJNIEnv.CallFloatMethod(objectMotionEvent, methodGetAxisValue, 0x00000001);

    lJNIEnv.DeleteLocalRef(classMotionEvent);
    lJNIEnv.DeleteLocalRef(objectMotionEvent);

    // Create and send our mouse wheel event
    Event::MouseWheelScrolled event;