C++/CLI - Managed class to C# events

Question

I have a c++ class that triggers some method like an event.

class Blah {

   virtual void Event(EventArgs e);
}

How can I wrap it so whenever the method is called a C# (managed) event will be called?

I thought of inheriting that class and overloading the event method, and then somehow call the managed event. I'm just not sure how to actually do it.

Answer 1

Something like this (now compile-tested):

#include <vcclr.h>

struct blah_args
{
    int x, y;
};

struct blah
{
    virtual void Event(const blah_args& e) = 0;
};

public ref class BlahEventArgs : public System::EventArgs
{
public:
    int x, y;
};

public ref class BlahDotNet
{
public:
    event System::EventHandler<BlahEventArgs^>^ ItHappened;
internal:
    void RaiseItHappened(BlahEventArgs^ e) { ItHappened(this, e); }
};

class blah_event_forwarder : public blah
{
    gcroot<BlahDotNet^> m_managed;

public:
    blah_event_forwarder(BlahDotNet^ managed) : m_managed(managed) {}

protected:
    virtual void Event(const blah_args& e)
    {
        BlahEventArgs^ e2 = gcnew BlahEventArgs();
        e2->x = e.x;
        e2->y = e.y;
        m_managed->RaiseItHappened(e2);
    }
};