【JUCEプラグイン開発】ディレイエフェクトの効果をDAWのテンポと同期する

class TheDelayAudioProcessor  : public juce::AudioProcessor
{
//...略...

private:
    //...略...

    //privateなメンバの準備です。
    juce::AudioPlayHead* playHead;
    juce::AudioPlayHead::CurrentPositionInfo currentPositionInfo;
    double current_bpm = 0.0;
    double previous_bpm = 0.0;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (TheDelayAudioProcessor)
};

void TheDelayAudioProcessor::prepareToPlay (double sampleRate, int samplesPerBlock)
{
    processorChain.prepare({ sampleRate, (juce::uint32) samplesPerBlock, 2 });

    //[1]DAWのBPMを取得します。
    playHead = this->getPlayHead();
    playHead->getCurrentPosition(currentPositionInfo);

    //[2]BPMを変数に保持します。
    current_bpm = currentPositionInfo.bpm;
    previous_bpm = current_bpm;

    //[3]val2とval3を取得した値に変更しました。
    float val2 = (float)60.0 / current_bpm;

    //[3-1]MaxDelayTimeとして設定した値を越えないようにします。
    if (val2 >= 2.0f) {
        val2 = 1.99f;
    }
    //[3-2]左右チャンネルで同じ時間としました。
    float val3 = val2;

    float val4 = *wetLevel;
    float val5 = *feedback;

    processorChain.get<DelayIndex>().setDelayTime(0, val2);
    processorChain.get<DelayIndex>().setDelayTime(1, val3);
    processorChain.get<DelayIndex>().setWetLevel(val4);
    processorChain.get<DelayIndex>().setFeedback(val5);
}

void TheDelayAudioProcessor::processBlock (juce::AudioBuffer<float>& buffer, juce::MidiBuffer& midiMessages)
{
//...略...

    //[1]DAWのBPMを取得します。
    playHead = this->getPlayHead();
    playHead->getCurrentPosition(currentPositionInfo);

    current_bpm = currentPositionInfo.bpm;

    //[2]BPMに変化があった場合処理をします。
    if (previous_bpm != current_bpm) {
        float val2 = (float)60.0 / current_bpm;

        if (val2 >= 2.0f) {
            val2 = 1.99f;
        }
        float val3 = val2;

        processorChain.get<DelayIndex>().setDelayTime(0, val2);
        processorChain.get<DelayIndex>().setDelayTime(1, val3);

        previous_bpm = current_bpm;
    }

    float val4 = *wetLevel;
    float val5 = *feedback;
    processorChain.get<DelayIndex>().setWetLevel(val4);
    processorChain.get<DelayIndex>().setFeedback(val5);
 
    auto block = juce::dsp::AudioBlock<float>(buffer).getSubBlock((size_t)0, (size_t)buffer.getNumSamples());
    auto context = juce::dsp::ProcessContextReplacing<float>(block);
    processorChain.process(context);
}