Question

I have a win32 wrapper class with a functioning WndProc (i use a static wndproc to forward messages to the WndProc member function).

I also have another app class which creates an instance of my win32 wrapper class.

I want the user of the app class to be able to write their own functions that represent events, such as OnMouseClick(), or OnMouseMove(), but in order for this to work, I need to call the event functions from the win32 wrapper class’s Wndproc (which has no knowledge of the app class).

What’s the best way to do this? Should I send a pointer to each event function to my win32 wrapper class, and call it via pointer? Or is there a better way?

Answer 1

The structure of your classes and their purpose is not clear. Nevertheless, the typical recommnded structure of wrapper classes is the following:

class BaseClass
{
public:
    virtual void OnMouseClick(...) { }   // Empty body
    virtual void OnMouseMove(...) { }   // Empty body
};

class AppClass : public BaseClass
{
public:
    void OnMouseClick(...) { AppCode }
    void OnMouseMove(...) { AppCode }
};

Base class is calling virtual methods when it receives Windows events in its static WndProc handler. And this triggers execution of the app code.