Qt鼠标移动事件未被事件过滤器捕获

这是我的事件过滤器：

bool
MapWidget_c::eventFilter( QObject *obj, QEvent *ev )
{
   if( obj == graphicsGeoMap_mp ||
       obj == graphicsScene_mp ||
       obj == graphicsView_mp )
   {
      if( ev->type() == QEvent::MouseMove )
      {
         QMouseEvent *mouseEvent = static_cast< QMouseEvent* >( ev );

         mouseMoveEvent( mouseEvent );

         return true;
      }
      else
      {
         return false;
      }
   }
   else
   {
      // pass the event on to the parent class
      return QWidget::eventFilter( obj, ev );
   }
}

我像这样安装过滤器：

graphicsGeoMap_mp->installEventFilter( this ); //QGraphicsGeoMap
graphicsScene_mp->installEventFilter( this ); //QGraphicsScene
graphicsView_mp->installEventFilter( this ); //QGraphicsScene

事件过滤器似乎捕获mousePress和mouseRelease事件就好了,但不是mouseMove.

可能是什么问题呢？

我应该一直在捕捉QEvent :: GraphicsSceneMouseMove事件而不是QEvent :: MouseMove事件.