JUCE/examples/PlugInSamples/Arpeggiator/Source/Arpeggiator.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2017 - ROLI Ltd.

   JUCE is an open source library subject to commercial or open-source
   licensing.

   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
   27th April 2017).

   End User License Agreement: www.juce.com/juce-5-licence
   Privacy Policy: www.juce.com/juce-5-privacy-policy

   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

#include "../JuceLibraryCode/JuceHeader.h"

//==============================================================================
/**
 */
class Arpeggiator  : public AudioProcessor
{
public:

    //==============================================================================
    Arpeggiator()
        : AudioProcessor (BusesProperties()) // add no audio buses at all
    {
        addParameter (speed = new AudioParameterFloat ("speed", "Arpeggiator Speed", 0.0, 1.0, 0.5));
    }

    ~Arpeggiator() {}

    //==============================================================================
    void prepareToPlay (double sampleRate, int samplesPerBlock) override
    {
        ignoreUnused (samplesPerBlock);

        notes.clear();
        currentNote = 0;
        lastNoteValue = -1;
        time = 0.0;
        rate = static_cast<float> (sampleRate);
    }

    void releaseResources() override {}

    void processBlock (AudioBuffer<float>& buffer, MidiBuffer& midi) override
    {
        // the audio buffer in a midi effect will have zero channels!
        jassert (buffer.getNumChannels() == 0);

        // however we use the buffer to get timing information
        auto numSamples = buffer.getNumSamples();

        // get note duration
        auto noteDuration = static_cast<int> (std::ceil (rate * 0.25f * (0.1f + (1.0f - (*speed)))));

        MidiMessage msg;
        int ignore;

        for (MidiBuffer::Iterator it (midi); it.getNextEvent (msg, ignore);)
        {
            if      (msg.isNoteOn())  notes.add (msg.getNoteNumber());
            else if (msg.isNoteOff()) notes.removeValue (msg.getNoteNumber());
        }

        midi.clear();

        if ((time + numSamples) >= noteDuration)
        {
            auto offset = jmax (0, jmin ((int) (noteDuration - time), numSamples - 1));

            if (lastNoteValue > 0)
            {
                midi.addEvent (MidiMessage::noteOff (1, lastNoteValue), offset);
                lastNoteValue = -1;
            }

            if (notes.size() > 0)
            {
                currentNote = (currentNote + 1) % notes.size();
                lastNoteValue = notes[currentNote];
                midi.addEvent (MidiMessage::noteOn  (1, lastNoteValue, (uint8) 127), offset);
            }

        }

        time = (time + numSamples) % noteDuration;
    }

    //==============================================================================
    bool isMidiEffect() const override                  { return true; }

    //==============================================================================
    AudioProcessorEditor* createEditor() override       { return new GenericAudioProcessorEditor (this); }
    bool hasEditor() const override                     { return true;   }

    //==============================================================================
    const String getName() const override               { return "Arpeggiator"; }

    bool acceptsMidi() const override                   { return true; }
    bool producesMidi() const override                  { return true; }
    double getTailLengthSeconds() const override        { return 0; }

    //==============================================================================
    int getNumPrograms() override                          { return 1; }
    int getCurrentProgram() override                       { return 0; }
    void setCurrentProgram (int) override                  {}
    const String getProgramName (int) override             { return String(); }
    void changeProgramName (int , const String& ) override { }

    //==============================================================================
    void getStateInformation (MemoryBlock& destData) override
    {
        MemoryOutputStream (destData, true).writeFloat (*speed);
    }

    void setStateInformation (const void* data, int sizeInBytes) override
    {
        speed->setValueNotifyingHost (MemoryInputStream (data, static_cast<size_t> (sizeInBytes), false).readFloat());
    }

private:
    //==============================================================================
    AudioParameterFloat* speed;
    int currentNote, lastNoteValue;
    int time;
    float rate;
    SortedSet<int> notes;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Arpeggiator)
};

//==============================================================================
// This creates new instances of the plugin..
AudioProcessor* JUCE_CALLTYPE createPluginFilter()
{
    return new Arpeggiator();
}