拖放

从甲拖动到乙，在甲的mousePressEvent函数中，
QDrag *drag = new QDrag((QWidget*)this);       //一个拖放类
  QCursor cursor(Qt::OpenHandCursor);           //鼠标显示用的
  QMimeData *mimeData = new QMimeData;     //基础数据类
// 设置了拖动参数
  QByteArray thename = m_currClickedItem->text(m_currClickedItemcol).toAscii();
  mimeData->setData("name", thename);
  mimeData->setText(m_currClickedItem->text(m_currClickedItemcol));
  // 数据传递
  drag->setMimeData(mimeData);
  // 放大图标
  QIcon icon(QPixmap(":/icons/template.png" ));
  QPixmap cursorpic(icon.pixmap(64,64));
  drag->setPixmap(cursorpic);//拖动图片
  drag->setDragCursor(cursorpic, Qt::MoveAction);

  Qt::DropAction dropAction = drag->exec();
  event->accept();

乙：
void 乙::dragEnterEvent ( QGraphicsSceneDragDropEvent * event )
{
    if (QString(event->mimeData()->data("name")) != "" ) {
        event->acceptProposedAction();
    }
}