Thread: Encapsulating DlgProc

Main.cpp

Code:

#include <windows.h>
#include "Resource.h"
#include "utils.h"
#include "main.h"

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
	CDlg *pDlg = new CDlg(hInstance);
	pDlg->SetTemplate(MAKEINTRESOURCE(IDD_DIALOG1));
	if (!pDlg->AllocDlg())
	{
		MessageBox(0, "No dlg", "Error", 16);
	}
	pDlg->FreeDlg();
	delete pDlg;
	return 0;
}

main.h

Code:

class CDlg
{
public:
	CDlg(HINSTANCE hInstance) : g_hInstance(hInstance){}
	~CDlg()
	{
		delete[] pTemplate;
	}
	void SetTemplate(const char *lpTemplate)
	{
		int iSize = _lstrlen(lpTemplate);
		pTemplate = new char[iSize+1];
		_lstrcpy(pTemplate, lpTemplate);
	}
	bool AllocDlg()
	{
		hDlg = CreateDialog(g_hInstance, pTemplate, 0, DLGPROC(DlgProc));
		return (hDlg ? true : false);
	}
	void FreeDlg()
	{
		if (hDlg) DestroyWindow(hDlg);
	}
	static LRESULT CALLBACK DlgProc(HWND hwnd, UINT Msg, WPARAM wParam, LPARAM lParam)
	{
		MessageBox(NULL, NULL, "Call 1", 0);
		CDlg *Obj = reinterpret_cast<CDlg*>(GetWindowLong(hwnd, GWL_USERDATA));
		if (Obj)
		{
			switch(Msg)
			{
			case WM_INITDIALOG:
				{
					SetWindowLong(hwnd, GWL_USERDATA, (LONG)Obj);
					return Obj->DlgProc(hwnd, Msg, wParam, lParam);
				}
			case WM_CLOSE:
				{
					DestroyWindow(hwnd);
					return Obj->DlgProc(hwnd, Msg, wParam, lParam);
				}
			case WM_DESTROY:
				{
					PostQuitMessage(0);
					return Obj->DlgProc(hwnd, Msg, wParam, lParam);
				}
			}
			return Obj->DlgProc(hwnd, Msg, wParam, lParam);
		}
		else
		{
			return Obj->DlgProc(hwnd, Msg, wParam, lParam);
		}
	}
protected:
private:
	HINSTANCE g_hInstance;
	char *pTemplate;
	HWND hDlg;
};

My executable crashes...any ideas?

Code:

CDlg *Obj = reinterpret_cast<CDlg*>(GetWindowLong(hwnd, GWL_USERDATA));
if (Obj)
{
//...
}
else
{
  return Obj->DlgProc(hwnd, Msg, wParam, lParam);
}

So if Obj is null, you try to use it? What you are trying to do simply doesn't make sense. I assume you want to associate an instance of the CDlg class with the hwnd of the dialog.

You should either pass a pointer to a CDlg object as the lParam of the WM_INITDIALOG message (probably using the CreateDialogParam function instead of the CreateDialog macro) or you can create a CDlg object locally in your Dialog procedure. I actually prefer to use a std::map (untested since I don't have access to a compiler atm):

Code:

static LRESULT CALLBACK DlgProc(HWND hwnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
  static std::map<HWND,CDlg> hDlg;
  switch (msg)
  {
    case WM_INITDIALOG:
      hDlg[hwnd] = new CDlg;//also free this before the window is destroyed
    break;
  }
}

Hi JaWiB

Maybe you can help...
If I'm change to CreateDialogParam, how can I fix the DlgProc?
Thanks

You would replace CreateDialog with this:

Code:

hDlg = CreateDialogParam(g_hInstance, pTemplate, 0,DLGPROC(DlgProc),reinterpret_cast<LPARAM>(this));

Then you have to fix your DlgProc:

Code:

if (Obj)
{
//...
}
else if (Msg==WM_INITDIALOG)
{
  SetWindowLong(hwnd,GWL_USERDATA,static_cast<LONG>(lParam));
}

And take a look at these lines:

Code:

return Obj->DlgProc(hwnd, Msg, wParam, lParam);

You're calling DlgProc recursively (it won't ever return).

Ok, thanks..

and thanks everyone for helping me seeing that error... lol

Ok, this compiles correctly, but..always returns "Obj is invalid"

Code:

static LRESULT CALLBACK DlgProc(HWND hwnd, UINT Msg, WPARAM wParam, LPARAM lParam)
	{
		CDlg *Obj = NULL;
		switch(Msg)
		{
		case WM_INITDIALOG:
			{
				Obj = reinterpret_cast<CDlg*>(GetWindowLong(hwnd, GWL_USERDATA));
				break;
			}
		case WM_COMMAND:
			{
				switch(LOWORD(wParam))
				{
				case IDC_BUTTON1:
					{
						if (Obj)
						{
							char *p;
							int iSize = GetWindowTextLength(Obj->GetCtrlHandle(IDC_EDIT1));
							p = new char[iSize+1];
							GetWindowText(Obj->GetCtrlHandle(IDC_EDIT1), p, iSize+1);
							MessageBox(hwnd, p, "Mensaje", 64);
							delete[] p;
						}
						else
						{
							// Error Handler
							MessageBox(hwnd, "Obj is invalid", "Beep", 16);
						}
						break;
					}
				}
				break;
			}
		case WM_CLOSE:
			{
				delete[] Obj;
				DestroyWindow(hwnd);
				break;
			}
		case WM_DESTROY:
			{
				PostQuitMessage(0);
				break;
			}
		}
		return 0;
	}
	bool AllocDlg()
	{
		hDlg = CreateDialog(g_hInstance, MAKEINTRESOURCE(id), 0, DLGPROC(DlgProc));
		SetWindowLong(hDlg, GWL_USERDATA, reinterpret_cast<LONG>(this));
		return (hDlg ? true : false);
	}

/Edit: Never mind... I solved it

Ok, I have a final question here:

Code:

static LRESULT CALLBACK DlgProc(HWND hwnd, UINT Msg, WPARAM wParam, LPARAM lParam)
	{
		CDlg *Obj = reinterpret_cast<CDlg*>(GetWindowLong(hwnd, GWL_USERDATA));
		switch(Msg)
		{
		case WM_INITDIALOG:
			{
				if (!IfFileExists("C:\\joel\\dev\\Projectos\\ini_1\\ini.ini"))
				{
					MessageBox(hwnd, "No ini found", "Beep", 16);
				}
				else
				{
					char *s = new char[28];
					ReadINIStr("C:\\joel\\dev\\Projectos\\ini_1\\ini.ini", "info", "msg", s);
					Obj->SetCtrlText(s, IDC_EDIT1); // Crash :(
					delete[] s;
				}
				break;
			}
// so on..

Why Obj is not valid on WM_INITDIALOG and after that works propertly? Is it possible to change this?

Thanks