Now I am rewrite the function paint() of the QGraphicsPolygonItem,For example :
Qt Code: 
  1. void QGraphicsTextItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
  2.                               QWidget *widget)
  3. {
  4.     Q_UNUSED(widget);
  5.     if (dd->control) {
  6.         painter->save();
  7.         QRectF r = option->exposedRect;
  8.         painter->translate(-dd->controlOffset());
  9.         r.translate(dd->controlOffset());
  10.         dd->control->drawContents(painter, r);
  11.         painter->restore();
  12.     }
  13.  
  14.     if (option->state & (QStyle::State_Selected | QStyle::State_HasFocus))
  15.         qt_graphicsItem_highlightSelected(this, painter, option);
  16. }
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the last two sentences is the Selected state,and delete them.