CCmdTarget::BeginWaitCursor
当您需要一个命令带花费大量的时间间隔执行时,调用此功能公开光标作为一个沙漏。
void BeginWaitCursor( );
备注
框架调用此功能公开用户它很忙,例如,当 CDocument 对象加载或保存为文件时。
因为其他操作,例如处理的 OnSetCursor,可以更改光标,BeginWaitCursor 的事件并不总是一个消息处理程序的有效外部。
调用 EndWaitCursor 还原了以前的光标。
示例
// 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
}
要求
Header: afxwin.h