OOP with windows message loops problem

Hi all,

I have 2 classes Class1 and mainWindow. mainWindow has a function with the following signature:

Code:

mainWindow::DetectorProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)

Now Class1 has the WinMain entry point and it also has the WinProc procedure to deal with the messages. Now what I want to do is create a dialogue from a resource file which I have created and to tell it to use the DetectorProc function in the other class. I tried this but with no luck, this is in the WinProc procedure of Class1.

Code:

case WM_CREATE:
			{
				mainWindow = CreateDialog(GetModuleHandle(NULL), MAKEINTRESOURCE(IDC_GUIMAIN),
					hwnd, mainWindow::DetectorProc);
			
				if(mainWindow != NULL)
				{
					ShowWindow(mainWindow, SW_SHOW);
				}
			}
			break;

However I get the following error message:

Code:

error C2664: 'CreateDialogParamA' : cannot convert parameter 4 from 'int (__stdcall mainWindow::*)(struct HWND__ *,unsigned in
t,unsigned int,long)' to 'int (__stdcall *)(struct HWND__ *,unsigned int,unsigned int,long)'

I tried doin the following but with no luck (it compiled fine but it seems tha the DetectorProc procedure wasnt getting the messages)

Code:

case WM_CREATE:
			{
typedef int (CALLBACK *DetectorProc)(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam);

				DetectorProc dp;
				dp = (DetectorProc)::GetProcAddress((HINSTANCE)mainWindow, "DetectorProc");
				mainWindow = CreateDialog(GetModuleHandle(NULL), MAKEINTRESOURCE(IDC_GUIMAIN),
					hwnd, dp);
			
				if(mainWindow != NULL)
				{
					ShowWindow(mainWindow, SW_SHOW);
				}
			}
			break;

Hopefully you can understand what im trying to do and can show me the right path as im pretty sure im not suppossed to use GetProcAddress as I have done above.

Thanks for any help

Well most C++ class member functions receive a 'this' pointer as a hidden parameter, which is obviously not going to be accounted for when windows calls your callback function.

If you want to have your window procedure in a class, it needs to be static like this:

Code:

class mainWindow:
{
public:
static LRESULT CALLBACK EditProc(HWND,UINT,WPARAM,LPARAM);
}

However, you won't be able to access any non-static data in the class so you need to associate an object of your class with the hwnd of the window in some way. For example, using a std::map:

Code:

static std::map<HWND,mainWindow*> Win;
switch (msg)
{
//...
case WM_NCCREATE:
    {
      Win[hwnd] = new mainWindow;
    }

}

I know this has been discussed before so I'll see if I can find a link or two to threads that give a better explanation.

Ah here we go.