Using unmanaged dll with c#

Question

I've been trying to create ac# wrapper for a c++ class I have created. I've looked around on how to do this but none of the examples seem to use classes and objects. I have the following code in c++:

#ifndef PORTAUDIOMANAGER_H
#define PORTAUDIOMANAGER_H

#include "portaudio.h"
#include "pa_asio.h"

class PortAudioManager
{
public:
    PortAudioManager();
    virtual ~PortAudioManager();

    static PortAudioManager* createObject();
    void openStream();

    void dispose(PortAudioManager* obj);

    void stopStream();

    typedef struct
    {
        float left_phase;
        float right_phase;
    }
    paTestData;

private:
    void* stream;

    paTestData data;
    static PortAudioManager* audioManager;
};

#endif

The createObject method creates a new object of PortAudioManager and registers it to the audioManager pointer. The dispose method acts as the destructor (since I thought you can't use the constructor and destructor in C#).

So how it should be used is simply like this:

PortAudioManager manager = PortAudioManager.createObject();
manager.openStream();

How would I go about creating a system that this can be used in c#? If you need more information, let me know.

Answer 1

Create a new class library project and compile with the /clr flag. Given the native C++ class presented above, add the following C++/CLI class to wrap your native class:

public ref class PortAudioManagerManaged
{
private:
    PortAudioManagerManaged(PortAudioManager* native)
        : m_native(native) { }

public:
    PortAudioManagerManaged()
        : m_native(new PortAudioManager) { }

    // = IDisposable.Dispose
    virtual ~PortAudioManagerManaged() {
        this->!PortAudioManagerManaged();
    }

    // = Object.Finalize
    !PortAudioManagerManaged() {
        delete m_native;
        m_native = nullptr;
    }

    static PortAudioManagerManaged^ CreateObject()
    {
        return gcnew PortAudioManagerManaged(PortAudioManager::createObject());
    }

    void OpenStream()
    {
        if (!m_native)
            throw gcnew System::ObjectDisposedException(GetType()->FullName);
        m_native->openStream(); 
    }

    void StopStream()
    {
        if (!m_native)
            throw gcnew System::ObjectDisposedException(GetType()->FullName);
        m_native->stopStream(); 
    }

private:
    PortAudioManager* m_native;
};

In your C# project, add a reference to your C++/CLI class library.

using (PortAudioManagerManaged manager = PortAudioManagerManaged.CreateObject())
{
    manager.OpenStream();
}