Archive for March, 2011

Useful function: EnableWindowsDependingOn

Monday, March 21st, 2011

One of my favorite internal functions. It helps my manage my app’s GUI. Checkboxes that cause their sub-elements to be greyed out when not checked can be easily handled by this:

bool EnableWindowsDependingOn (CWnd *pParent, DWORD DependingOnThisCheckbox, DWORD Value1, ...)
 va_list marker;

 bool bState = (((CButton*)pParent->GetDlgItem(DependingOnThisCheckbox))->GetCheck()!=0);

 DWORD i=Value1;
 va_start (marker, Value1);
 while (i != 0)
 if (i<=0xffff)
 if (pParent->GetDlgItem(i))
 pParent->GetDlgItem(i)->EnableWindow (bState);
 ((CWnd*)i)->EnableWindow (bState);

 i = va_arg (marker, long);
 va_end (marker);

 return (bState);

It accepts the “this-pointer” of your CDialog and the id of the master checkbox. Then you can append any number of sub-element ids or pointers. And finally a NULL. Example:
EnableWindowsDependingOn (this, IDC_CHECK1, IDC_EDIT1, IDC_EDIT2, NULL);

This would enable the two edit boxes if the checkbox is enabled.