问如何在qt中包含菜单项的工具提示

EN

// Qt header:
#include <QtWidgets>

/// menu bar with tooltips
class MenuBar: public QMenuBar {
  public:
    explicit MenuBar(QWidget *pQParent = nullptr): QMenuBar(pQParent) { }
    virtual ~MenuBar() = default;
    MenuBar(const MenuBar&) = delete;
    MenuBar& operator=(const MenuBar&) = delete;

  protected:
    virtual bool event(QEvent *pQEvent) override;
};

bool MenuBar::event(QEvent *pQEvent)
{
  // keep behavior of base class
  bool ret = QMenuBar::event(pQEvent);
  // check whether this is a help event
  if (pQEvent->type() == QEvent::ToolTip) {
    const QHelpEvent *const pQHelpEvent = (const QHelpEvent*)pQEvent;
    const QAction *pQAction = activeAction();
    if (pQAction && !pQAction->toolTip().isEmpty()) {
      QToolTip::showText(pQHelpEvent->globalPos(), pQAction->toolTip());
      return ret;
    }
  }
  QToolTip::hideText();
  return ret;
}

/// menu with tooltips
class Menu: public QMenu {
  public:
    explicit Menu(const QString &title, QWidget *pQParent = nullptr):
      QMenu(title, pQParent)
    { }
    explicit Menu(QWidget *pQParent = nullptr): QMenu(pQParent) { }
    virtual ~Menu() = default;
    Menu(const Menu&) = delete;
    Menu& operator=(const Menu&) = delete;

  protected:
    virtual bool event(QEvent *pQEvent) override;
};

bool Menu::event(QEvent *pQEvent)
{
  // keep behavior of base class
  bool ret = QMenu::event(pQEvent);
  // check whether this is a help event
  if (pQEvent->type() == QEvent::ToolTip) {
    const QHelpEvent *const pQHelpEvent = (const QHelpEvent*)pQEvent;
    const QAction *pQAction = activeAction();
    if (pQAction && !pQAction->toolTip().isEmpty()) {
      QToolTip::showText(pQHelpEvent->globalPos(), pQAction->toolTip());
      return ret;
    }
  }
  QToolTip::hideText();
  return ret;
}

// main application
int main(int argc, char **argv)
{
  qDebug() << "Qt Version:" << QT_VERSION_STR;
  QApplication app(argc, argv);
  // setup GUI
  QMainWindow qWinMain;
  qWinMain.resize(320, 240);
  qWinMain.setWindowTitle("Test QMenuBar with ToolTips");
  MenuBar qMenuBar;
  QAction qCmdFile("File");
  qCmdFile.setToolTip("provides file commands.");
  Menu qMenuFile;
  QAction qCmdExit("Quit");
  qCmdExit.setToolTip("closes application.");
  qMenuFile.addAction(&qCmdExit);
  qCmdFile.setMenu(&qMenuFile);
  qMenuBar.addAction(&qCmdFile);
  qWinMain.setMenuBar(&qMenuBar);
#if 0 // comparison with toolbar
  QToolBar qToolBar;
  qToolBar.addAction(&qCmdExit);
  qWinMain.addToolBar(&qToolBar);
#endif // 0
  qWinMain.show();
  // runtime loop
  return app.exec();
}

SOURCES = testQMenuBarToolTips.cc

QT += widgets

$ qmake-qt5 

$ make && ./testQMenuBarToolTips
g++ -c -fno-keep-inline-dllexport -D_GNU_SOURCE -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I. -isystem /usr/include/qt5 -isystem /usr/include/qt5/QtWidgets -isystem /usr/include/qt5/QtGui -isystem /usr/include/qt5/QtCore -I. -I/usr/lib/qt5/mkspecs/cygwin-g++ -o testQMenuBarToolTips.o testQMenuBarToolTips.cc
g++  -o testQMenuBarToolTips.exe testQMenuBarToolTips.o   -lQt5Widgets -lQt5Gui -lQt5Core -lGL -lpthread 
Qt Version: 5.9.4