CCmdTarget::BeginWaitCursor

Artigo
03/26/2013

Chamar essa função para exibir o cursor como uma ampulheta quando você espera um comando obter um intervalo de tempo visível para executar.

void BeginWaitCursor( );

Comentários

A estrutura chama essa função para mostrar o usuário que está ocupado, como quando um objeto de CDocument carregar ou se salva em um arquivo.

As ações de BeginWaitCursor não são sempre eficiente fora de um único manipulador de mensagem porque outras ações, como OnSetCursor que trata, poderiam mudar o cursor.

Chamada EndWaitCursor para restaurar o cursor anterior.

Exemplo

// 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::OnBeginSleepEnd()
{
   BeginWaitCursor(); // display the hourglass cursor
   // do some lengthy processing
   Sleep(3000);
   EndWaitCursor(); // remove the hourglass cursor
}

// The next example illustrates RestoreWaitCursor.
void CMyView::OnBeginDlgRestore()
{
   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.
   CFileDialog dlg(TRUE);
   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
   Sleep(3000);
   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::OnDlgRestore()
{
   // some processing ...
   CFileDialog dlg(TRUE);
   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::OnDlgDoWait()
{
   CFileDialog dlg(TRUE);
   dlg.DoModal();
   AfxGetApp()->DoWaitCursor(0); // same as CCmdTarget::RestoreWaitCursor   
}