JUCE/examples/PlugInSamples/GainPlugIn/Source/GainProcessor.cpp

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

 This file is part of the JUCE library.
 Copyright (c) 2015 - ROLI Ltd.

 Permission is granted to use this software under the terms of either:
 a) the GPL v2 (or any later version)
 b) the Affero GPL v3

 Details of these licenses can be found at: www.gnu.org/licenses

 JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

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

 To release a closed-source product which uses JUCE, commercial licenses are
 available: visit www.juce.com for more information.

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

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

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

    //==============================================================================
    GainProcessor()
    {
        addParameter (gain = new AudioParameterFloat ("gain", "Gain", 0.0f, 1.0f, 0.5f));

        // Some VST-2 DAWs want the maximum amount of channels to be enabled by default
        if (wrapperType == wrapperType_VST)
        {
            busArrangement.inputBuses. getReference (0).channels = AudioChannelSet::discreteChannels (kVST2MaxChannels);
            busArrangement.outputBuses.getReference (0).channels = AudioChannelSet::discreteChannels (kVST2MaxChannels);
        }
    }

    ~GainProcessor() {}

    //==============================================================================
    void prepareToPlay (double, int) override {}
    void releaseResources() override {}

    void processBlock (AudioSampleBuffer& buffer, MidiBuffer&) override
    {
        buffer.applyGain (*gain);
    }

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

    //==============================================================================
    const String getName() const override               { return "Gain PlugIn"; }
    bool acceptsMidi() const override                   { return false; }
    bool producesMidi() const override                  { return false; }
    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 (*gain);
    }

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

    //==============================================================================
    bool setPreferredBusArrangement (bool isInputBus, int busIndex,
                                     const AudioChannelSet& preferred) override
    {
        const int numChannels = preferred.size();

        // do not allow disabling channels
        if (numChannels == 0)
            return false;

        // limit the amount of channels for VST-2
        if (wrapperType == wrapperType_VST && numChannels > kVST2MaxChannels)
            return false;

        // always have the same channel layout on both input and output on the main bus
        if (! AudioProcessor::setPreferredBusArrangement (! isInputBus, busIndex, preferred))
            return false;

        return AudioProcessor::setPreferredBusArrangement (isInputBus, busIndex, preferred);
    }

private:
    //==============================================================================
    AudioParameterFloat* gain;

    enum { kVST2MaxChannels = 16 };

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (GainProcessor)
};

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