This week you will be learning about refactoring into simpler modules and class composition. Download the starter code here (Link).

Create a new class in Projucer

To add a new class in Projucer, we first open the project in Projucer, select Source directory, then click the + button and choose Add New CPP & Header File… and name the file(s) DJAudioPlayer.

Note that if you don’t first select Source, the files will be outside of the Source folder. You will need to manually drag them into the Source folder.

Press CMD+S or CTRL+S to save the project in Projucer, then restart the IDE (Visual Studio or Xcode).

Implement the DJAudioPlayer skeleton

Go to DJAudioPlayer.h file, define the DJAudioPlayer class.

#pragma once

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

class DJAudioPlayer : public AudioSource {
public:
    DJAudioPlayer();
    ~DJAudioPlayer();
    
    //==============================================================================
    void prepareToPlay (int samplesPerBlockExpected, double sampleRate) override;
    void getNextAudioBlock (const AudioSourceChannelInfo& bufferToFill) override;
    void releaseResources() override;
    
    void loadURL(URL audioURL);
    void setGain(double gain);
    void setSpeed(double ratio);
    void setPosition(double posInSec);
    
    void start();
    void stop();
    
};

Next, implement the DJAudioPlayer class skeleton in the cpp file.

#include "DJAudioPlayer.h"

DJAudioPlayer::DJAudioPlayer(){}
DJAudioPlayer::~DJAudioPlayer(){}

//==============================================================================
void DJAudioPlayer::prepareToPlay (int samplesPerBlockExpected, double sampleRate) {}
void DJAudioPlayer::getNextAudioBlock (const AudioSourceChannelInfo& bufferToFill) {}
void DJAudioPlayer::releaseResources() {}

void DJAudioPlayer::loadURL(URL audioURL){}
void DJAudioPlayer::setGain(double gain){}
void DJAudioPlayer::setSpeed(double ratio){}
void DJAudioPlayer::setPosition(double posInSec){}

void DJAudioPlayer::start(){}
void DJAudioPlayer::stop(){}

Include the DJAudioPlayer in the MainComponent.h file to test if the program can compile.

#pragma once

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

...
class MainComponent   : public AudioAppComponent, 
                        public Button::Listener, 
                        public Slider::Listener
{
		...

		DJAudioPlayer player1;
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (MainComponent)
};

Build the project and check if you can build it successfully.