JUCE/examples/AudioAppExample/Source/MainComponent.cpp

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

    This file was auto-generated!

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

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


//==============================================================================
class MainContentComponent   : public AudioAppComponent
{
public:
    //==============================================================================
    MainContentComponent()
        : phase (0.0f),
          phaseDelta (0.0f),
          frequency (5000.0f),
          amplitude (0.2f),
          sampleRate (0.0),
          expectedSamplesPerBlock (0)
    {
        setSize (800, 600);

        // Specify the number of input and output channels that we want to open.
        setAudioChannels (0, 2);
    }

    ~MainContentComponent()
    {
        shutdownAudio();
    }

    //==============================================================================
    void prepareToPlay (int samplesPerBlockExpected, double newSampleRate) override
    {
        sampleRate = newSampleRate;
        expectedSamplesPerBlock = samplesPerBlockExpected;
    }

    /*  This method generates the actual audio samples.
        In this example the buffer is filled with a sine wave whose frequency and
        amplitude are controlled by the mouse position.
     */
    void getNextAudioBlock (const AudioSourceChannelInfo& bufferToFill) override
    {
        bufferToFill.clearActiveBufferRegion();
        const float originalPhase = phase;

        for (int chan = 0; chan < bufferToFill.buffer->getNumChannels(); ++chan)
        {
            phase = originalPhase;

            float* const channelData = bufferToFill.buffer->getWritePointer (chan, bufferToFill.startSample);

            for (int i = 0; i < bufferToFill.numSamples ; ++i)
            {
                channelData[i] = amplitude * std::sin (phase);

                // increment the phase step for the next sample
                phase = std::fmod (phase + phaseDelta, float_Pi * 2.0f);
            }
        }
    }

    void releaseResources() override
    {
        // This gets automatically called when audio device parameters change
        // or device is restarted.
    }


    //==============================================================================
    void paint (Graphics& g) override
    {
        // (Our component is opaque, so we must completely fill the background with a solid colour)
        g.fillAll (Colours::black);

        const float centreY = getHeight() / 2.0f;
        const float radius = amplitude * 200.0f;

        // Draw an ellipse based on the mouse position and audio volume
        g.setColour (Colours::lightgreen);
        g.fillEllipse  (lastMousePosition.x - radius / 2.0f,
                        lastMousePosition.y - radius / 2.0f,
                        radius, radius);

        // Draw a representative sine wave.
        Path wavePath;
        wavePath.startNewSubPath (0, centreY);

        for (float x = 1.0f; x < getWidth(); ++x)
            wavePath.lineTo (x, centreY + amplitude * getHeight() * 2.0f
                                            * std::sin (x * frequency * 0.0001f));

        g.setColour (Colours::grey);
        g.strokePath (wavePath, PathStrokeType (2.0f));
    }

    // Mouse handling..
    void mouseDown (const MouseEvent& e) override
    {
        mouseDrag (e);
    }

    void mouseDrag (const MouseEvent& e) override
    {
        lastMousePosition = e.position;

        frequency = (getHeight() - e.y) * 10.0f;
        amplitude = jmin (0.9f, 0.2f * e.position.x / getWidth());

        phaseDelta = (float) (2.0 * double_Pi * frequency / sampleRate);

        repaint();
    }

    void mouseUp (const MouseEvent&) override
    {
        amplitude = 0.0f;
        repaint();
    }

    void resized() override
    {
        // This is called when the MainContentComponent is resized.
        // If you add any child components, this is where you should
        // update their positions.
    }


private:
    //==============================================================================
    float phase;
    float phaseDelta;
    float frequency;
    float amplitude;

    double sampleRate;
    int expectedSamplesPerBlock;
    Point<float> lastMousePosition;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (MainContentComponent)
};


Component* createMainContentComponent() { return new MainContentComponent(); };