CCmdTarget::BeginWaitCursor

void BeginWaitCursor ( );

Osservazioni

Chiamare questa funzione per visualizzare il cursore come una clessidra quando aspettiamo un comando per prendere un intervallo di tempo notevole per l'esecuzione. Il framework chiama questa funzione per mostrare all'utente che occupato, come ad esempio quando un oggetto CDocument carica o si salva in un file.

Le azioni di BeginWaitCursor non sono sempre efficace di fuori di un gestore unico messaggio come altre azioni, come ad esempio OnSetCursor , manipolazione, potrebbe cambiare il cursore.

Chiamata EndWaitCursor per ripristinare il cursore precedente.

Esempio

// The following example illustrates the most common case
// of displaying the hourglass cursor during some lengthy
// processing of a command handler implemented in some
// CCmdTarget-derived class, such as a document or view.

void CMyView::OnSomeCommand()
{
   BeginWaitCursor(); // display the hourglass cursor

   // do some lengthy processing

   EndWaitCursor(); // remove the hourglass cursor
}

// The next example illustrates RestoreWaitCursor.
void CMyView::OnSomeCommand()
{
   BeginWaitCursor(); // display the hourglass cursor

   // do some lengthy processing

   // The dialog box will normally change the cursor to
   // the standard arrow cursor, and leave the cursor in
   // as the standard arrow cursor when the dialog box is
   // closed.
   CMyDialog dlg;
   dlg.DoModal();

   // It is necessary to call RestoreWaitCursor here in order
   // to change the cursor back to the hourglass cursor.
   RestoreWaitCursor();

   // do some more lengthy processing

   EndWaitCursor(); // remove the hourglass cursor
}

// In the above example, the dialog was clearly invoked between
// the pair of calls to BeginWaitCursor and EndWaitCursor.
// Sometimes it may not be clear whether the dialog is invoked 
// in between a pair of calls to BeginWaitCursor and EndWaitCursor.
// It is permissable to call RestoreWaitCursor, even if 
// BeginWaitCursor was not previously called.  This case is 
// illustrated below, where CMyView::AnotherFunction does not
// need to know whether it was called in the context of an
// hourglass cursor.
void CMyView::AnotherFunction()
{
   // some processing ...

   CMyDialog dlg;
   dlg.DoModal();
   RestoreWaitCursor();

   // some more processing ...
}

// If the dialog is invoked from a member function of
// some non-CCmdTarget, then you can call CWinApp::DoWaitCursor
// with a 0 parameter value to restore the hourglass cursor.
void CMyObject::AnotherFunction()
{
   CMyDialog dlg;
   dlg.DoModal();
   AfxGetApp()->DoWaitCursor(0); // same as CCmdTarget::RestoreWaitCursor   
}

Pa&noramica CCmdTarget |nbsp; Membri della classe | Gerarchia Chart

Vedere a&nchenbsp;CWaitCursor, CCmdTarget::EndWaitCursor, CCmdTarget::RestoreWaitCursor, CWinApp::DoWaitCursor

Index