Method valuesForTimeRangeImpl

src/core/AudioParamTimeline.cpp:175–406

}

float AudioParamTimeline::valuesForTimeRangeImpl(
    double startTime,
    double endTime,
    float defaultValue,
    float * values,
    size_t numberOfValues,
    double sampleRate,
    double controlRate)
{
    if (!values)
        return defaultValue;

    // Return default value if there are no events matching the desired time range.
    std::unique_lock<std::mutex> lock(m_eventsMutex, std::try_to_lock);
    if (!lock.owns_lock() || !m_events.size() || endTime <= m_events[0].time())
    {
        for (unsigned i = 0; i < numberOfValues; ++i)
            values[i] = defaultValue;
        return defaultValue;
    }

    // Maintain a running time and index for writing the values buffer.
    double currentTime = startTime;
    unsigned writeIndex = 0;

    // If first event is after startTime then fill initial part of values buffer with defaultValue
    // until we reach the first event time.
    double firstEventTime = m_events[0].time();
    if (firstEventTime > startTime)
    {
        double fillToTime = std::min(endTime, firstEventTime);
        size_t fillToFrame = AudioUtilities::timeToSampleFrame(fillToTime - startTime, sampleRate);
        fillToFrame = std::min(fillToFrame, numberOfValues);
        for (; writeIndex < fillToFrame; ++writeIndex)
            values[writeIndex] = defaultValue;

        currentTime = fillToTime;
    }

    float value = defaultValue;

    // Go through each event and render the value buffer where the times overlap,
    // stopping when we've rendered all the requested values.
    // FIXME: could try to optimize by avoiding having to iterate starting from the very first event
    // and keeping track of a "current" event index.
    int n = static_cast<int>(m_events.size());
    for (int i = 0; i < n && writeIndex < numberOfValues; ++i)
    {
        ParamEvent & event = m_events[i];
        ParamEvent * nextEvent = i < n - 1 ? &(m_events[i + 1]) : 0;

        // Wait until we get a more recent event.
        if (nextEvent && nextEvent->time() < currentTime)
            continue;

        float value1 = event.value();
        double time1 = event.time();
        float value2 = nextEvent ? nextEvent->value() : value1;