Question

I am attempting to make a custom GLWindow class that includes all of my setting up of my OpenGL window. However, I also want to include the WndProc callback function for messages being sent to the window in my GLWindow class.

GLWindow.h:

class GLWindow
{
    private:
        HWND hWnd;
        HDC hDC;
        HGLRC hRC;
    public:
        GLWindow();

        LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

        bool Create();

        ~GLWindow();
}

GLWindow.cpp:

GLWindow::GLWindow()
{

}

bool GLWindow::Create(int width, int height, char * title, bool fullscreen)
{
    WNDCLASSEX window;

    HINSTANCE hInstance;

    hInstance = GetModuleHandle(NULL);
    window.cbSize = sizeof(WNDCLASSEX);
    window.cbClsExtra = 0;
    window.cbWndExtra = 0;
    window.hbrBackground = NULL;
    window.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    window.hIconSm = LoadIcon(NULL, IDI_WINLOGO);
    window.hCursor = LoadCursor(NULL, IDC_ARROW);
    window.hInstance = hInstance;
    window.lpfnWndProc = GLWindow::WndProc; // ERROR
}

GLWindow::~GLWindow()
{

}

The Error is that a value of type “LRESULT (__stdcall GLWindow::*)(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)” cannot be assigned to an entity of type “WNDPROC.”

I can’t figure it out

I’ve gotten this to work when WndProc shares the same .cpp file as the WinMain function, but it seems as if the scope throws it off.

Answer 1

It should be a static or global function. Class member function expects to receive an additional hidden parameter called this, so the signature doesn’t match.