如何在程序启动时显示沙漏

Call this function to display the cursor as an hourglass when you expect a command to take a noticeable time interval to execute.

void BeginWaitCursor( );

Remarks

The framework calls this function to show the user that it is busy, such as when a CDocument object loads or saves itself to a file.

The actions of BeginWaitCursor are not always effective outside of a single message handler as other actions, such as OnSetCursor handling, could change the cursor.

Call EndWaitCursor to restore the previous cursor.

Example

// 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   
}