I like object-oriented programming. In my professional C++ career, I have used nothing but MFC. So, when I want to make a good ole' fashioned Win32/SDK application, I cringe at the thought of not using the OO paradigm. If you're like me and you want to get away from the old C programming style, here is some code that will help you write your own window wrapper class.
Where are all of the examples?
It's nearly impossible to find good examples of a window wrapper class. None of my game development books have one. None of my general Windows programming books do either. Conducting a Google search only gave me one good example, Creating a Win32 Window Wrapper Class. You would think more people would be doing this. Unfortunately, there aren't more examples because its not easy to get it working.
The main problem
When you create a
WNDCLASSEX structure you need to give the structure a pointer to your window procedure in the
lpfnWndProc member. The window procedure is a callback, a special kind of function called directly by Windows when needed.
To make callbacks work correctly, strict typedefs are defined in the Windows header files. If you try to use a class member as a callback, the compiler will give you an error, saying that the member prototype does not match the required typedef.
To get around this compiler error, we need to make the window procedure
static. From this static method we then call another method of the class to actually handle the messages.
To call the message handler of the correct window, we need to get the pointer of the window class using the
GetWindowLong API functions. We send the
this pointer to the window procedure via the
LPVOID lpParam // window-creation data parameter.
WM_NCCREATE message is received, the window procedure sets the window long value to the pointer and is then able to call the correct message handler.
static LRESULT CALLBACK stWinMsgHandler(HWND hwnd,
UINT uMsg, WPARAM wParam, LPARAM lParam);
virtual LRESULT CALLBACK WinMsgHandler(HWND hwnd,
UINT uMsg, WPARAM wParam, LPARAM lParam)=0;
inline static CBaseWindow *GetObjectFromWindow(HWND hWnd)
return (CBaseWindow *)GetWindowLong(hWnd, GWL_USERDATA);
LRESULT CALLBACK CBaseWindow::stWinMsgHandler(HWND hwnd,
UINT uMsg, WPARAM wParam, LPARAM lParam)
if (uMsg == WM_NCCREATE)
pWnd = GetObjectFromWindow(hwnd);
return pWnd->WinMsgHandler(hwnd, uMsg, wParam, lParam);
return DefWindowProc(hwnd, uMsg, wParam, lParam);
BOOL CBaseWindow::Create(DWORD dwStyles, RECT* rect)
m_hwnd = CreateWindow(szClassName, szWindowTitle, dwStyles,
rect->left, rect->top, rect->right - rect->left,
rect->bottom - rect->top, NULL, NULL, hInstance,
return (m_hwnd != NULL);
Although, the demo (and source) is a very simple and crude example of what you can do with a window wrapper class, I hope it will help make your Win32 programming projects easier to understand and your code more reusable.
If you can find more information on this subject, I would gladly add a links section to the article.
Credit where credit is due
I have been a professional developer since 1996. I live in the middle of no where in Illinois, USA. I am married and have four children.