JUCE/modules/juce_audio_devices/midi_io/juce_MidiMessageCollector.cpp

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

   This file is part of the JUCE library.
   Copyright (c) 2016 - ROLI Ltd.

   Permission is granted to use this software under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license/

   Permission to use, copy, modify, and/or distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
   copyright notice and this permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
   OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   OF THIS SOFTWARE.

   -----------------------------------------------------------------------------

   To release a closed-source product which uses other parts of JUCE not
   licensed under the ISC terms, commercial licenses are available: visit
   www.juce.com for more information.

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

MidiMessageCollector::MidiMessageCollector()
    : lastCallbackTime (0),
      sampleRate (44100.0001)
{
}

MidiMessageCollector::~MidiMessageCollector()
{
}

//==============================================================================
void MidiMessageCollector::reset (const double newSampleRate)
{
    jassert (newSampleRate > 0);

    const ScopedLock sl (midiCallbackLock);
    sampleRate = newSampleRate;
    incomingMessages.clear();
    lastCallbackTime = Time::getMillisecondCounterHiRes();
}

void MidiMessageCollector::addMessageToQueue (const MidiMessage& message)
{
    // you need to call reset() to set the correct sample rate before using this object
    jassert (sampleRate != 44100.0001);

    // the messages that come in here need to be time-stamped correctly - see MidiInput
    // for details of what the number should be.
    jassert (message.getTimeStamp() != 0);

    const ScopedLock sl (midiCallbackLock);

    const int sampleNumber
        = (int) ((message.getTimeStamp() - 0.001 * lastCallbackTime) * sampleRate);

    incomingMessages.addEvent (message, sampleNumber);

    // if the messages don't get used for over a second, we'd better
    // get rid of any old ones to avoid the queue getting too big
    if (sampleNumber > sampleRate)
        incomingMessages.clear (0, sampleNumber - (int) sampleRate);
}

void MidiMessageCollector::removeNextBlockOfMessages (MidiBuffer& destBuffer,
                                                      const int numSamples)
{
    // you need to call reset() to set the correct sample rate before using this object
    jassert (sampleRate != 44100.0001);
    jassert (numSamples > 0);

    const double timeNow = Time::getMillisecondCounterHiRes();
    const double msElapsed = timeNow - lastCallbackTime;

    const ScopedLock sl (midiCallbackLock);
    lastCallbackTime = timeNow;

    if (! incomingMessages.isEmpty())
    {
        int numSourceSamples = jmax (1, roundToInt (msElapsed * 0.001 * sampleRate));

        int startSample = 0;
        int scale = 1 << 16;

        const uint8* midiData;
        int numBytes, samplePosition;

        MidiBuffer::Iterator iter (incomingMessages);

        if (numSourceSamples > numSamples)
        {
            // if our list of events is longer than the buffer we're being
            // asked for, scale them down to squeeze them all in..
            const int maxBlockLengthToUse = numSamples << 5;

            if (numSourceSamples > maxBlockLengthToUse)
            {
                startSample = numSourceSamples - maxBlockLengthToUse;
                numSourceSamples = maxBlockLengthToUse;
                iter.setNextSamplePosition (startSample);
            }

            scale = (numSamples << 10) / numSourceSamples;

            while (iter.getNextEvent (midiData, numBytes, samplePosition))
            {
                samplePosition = ((samplePosition - startSample) * scale) >> 10;

                destBuffer.addEvent (midiData, numBytes,
                                     jlimit (0, numSamples - 1, samplePosition));
            }
        }
        else
        {
            // if our event list is shorter than the number we need, put them
            // towards the end of the buffer
            startSample = numSamples - numSourceSamples;

            while (iter.getNextEvent (midiData, numBytes, samplePosition))
            {
                destBuffer.addEvent (midiData, numBytes,
                                     jlimit (0, numSamples - 1, samplePosition + startSample));
            }
        }

        incomingMessages.clear();
    }
}

//==============================================================================
void MidiMessageCollector::handleNoteOn (MidiKeyboardState*, int midiChannel, int midiNoteNumber, float velocity)
{
    MidiMessage m (MidiMessage::noteOn (midiChannel, midiNoteNumber, velocity));
    m.setTimeStamp (Time::getMillisecondCounterHiRes() * 0.001);

    addMessageToQueue (m);
}

void MidiMessageCollector::handleNoteOff (MidiKeyboardState*, int midiChannel, int midiNoteNumber, float velocity)
{
    MidiMessage m (MidiMessage::noteOff (midiChannel, midiNoteNumber, velocity));
    m.setTimeStamp (Time::getMillisecondCounterHiRes() * 0.001);

    addMessageToQueue (m);
}

void MidiMessageCollector::handleIncomingMidiMessage (MidiInput*, const MidiMessage& message)
{
    addMessageToQueue (message);
}