How to drag and drop on QGraphicsView frame

[wudelei]

I wrote a picture browser.use QGraphicsScene,QGraphicsView,QGraphicsPixItem, display some small pictures on screen. How to drag QGraphicsView class to look other picture
I wrote three funtions :mousePressEvent(),dropEvent(),dragEnterEvent() in QGraphicsView's child class. But I don't konw how to realize these funtions........

[wudelei]

My project is in the Qt for symbian platform, it is similar to the image viewer, displayed a lot of small pictures on the screen,
but the screen only shows the part pictures, I would like to view other pictures using drag and drop way.
I know that these three functions is to realize drag and drop, :mousePressEvent(),dropEvent(),dragEnterEvent() , but I don't konw how to write code........