Finding Display Size of Dialog From Resource

There is no MFC support to find the display size of dialog from it's resource and it becomes even more painful to implement if dialog resides in a DLL and contains some ActiveX controls.

Here is the function to find it :

CRect CalcDialogSize(INT nResourceId, 
                     const char* strDllName=NULL)
{
 CRect rectSize;

 // if the dialog resource resides in a DLL ...
 //	
 HINSTANCE hExeResourceHandle;
 HINSTANCE hModule;

 if(strDllName != NULL)
 {
  hExeResourceHandle = AfxGetResourceHandle();

  hModule= ::LoadLibrary(strDllName);
  ASSERT(hModule);

  AfxSetResourceHandle(hModule);
 }

 HINSTANCE hInst = 
  AfxFindResourceHandle(MAKEINTRESOURCE(nResourceId),
                        RT_DIALOG);

 ASSERT(hInst != NULL);

 HRSRC hRsrc = ::FindResource(hInst, 
                              MAKEINTRESOURCE(nResourceId),
                              RT_DIALOG);
 ASSERT(hRsrc != NULL);

 HGLOBAL hTemplate = ::LoadResource(hInst, hRsrc);
 ASSERT(hTemplate != NULL);

 DLGTEMPLATE* pTemplate = (DLGTEMPLATE*)::LockResource(hTemplate);

 //Load coresponding DLGINIT resource 
 //(if we have any ActiveX components)
 //
 void* lpDlgInit;
 HGLOBAL hDlgInit = NULL;
 CDialog dlg;

 HRSRC hsDlgInit = ::FindResource(hInst, 
                                  MAKEINTRESOURCE(nResourceId),
                                  RT_DLGINIT);
 if (hsDlgInit != NULL)
 {
  // load it
  hDlgInit = ::LoadResource(hInst, hsDlgInit);
  ASSERT(hDlgInit != NULL);

  // lock it
  lpDlgInit = ::LockResource(hDlgInit);
  ASSERT(lpDlgInit != NULL);

  dlg.CreateIndirect(pTemplate, NULL, lpDlgInit);   
 }
 else
 {
  dlg.CreateIndirect(pTemplate, NULL);  
 }
		
 CRect rect;
 dlg.GetClientRect(rectSize);

 dlg.DestroyWindow();

 ::UnlockResource(hTemplate);
 ::FreeResource(hTemplate);
 if (hDlgInit) 
 {
  ::UnlockResource(hDlgInit);   
  ::FreeResource(hDlgInit);
 }	

 if(strDllName != NULL)
 {
  AfxSetResourceHandle(hExeResourceHandle);
  ::FreeLibrary(hModule);
 }

 return rectSize;
}