QTreeView对象怎么改变item的焦点（已解决） [复制链接]

用QTreeview定义的对象显示系统目录和图片文件，用鼠标和按钮Next，Prev可以切换图片的显示，我的问题是怎么在点击按钮的同时把treeview窗口的焦点改变。我看帮助文档有
void QTreeView::setSelection（）这个函数，不过他是纯虚函数，是在不知道怎么用。求各位老大解答，谢谢！

补充几句，顺便自己顶一下，
dirsTree = new QTreeView(this);
dirsModel = new QDirModel(list, QDir::AllDirs | QDir::NoDotAndDotDot | QDir::Files, QDir::Name);
dirsTree->setModel(dirsModel);

QItemSelectionModel * sel = treeView->selectionModel ();

sel->select(...);

谢谢你的回答，给了我启发，不过我没用这个实现。
void MyTreeview :: nextImage()
{
    QModelIndex currentIndex = dirsTree->currentIndex();
        if (dirsModel->isDir(currentIndex))
        {
        nextFlag = true;                            //标志位，当前index是dir值为true
        dirsTree->setExpanded(currentIndex, 1);
        currentIndex = currentIndex.child(0, 0);
        }
        QModelIndex currentIndexParent = currentIndex.parent();            //当前index的parent索引
        QModelIndex currentFolderStartIndex = currentIndex.model()->index(0, 0, currentIndexParent);    //当前目录第一个图片的index

    qint32 currentFolderTotal = currentIndex.model()->rowCount(currentIndexParent);    //当前目录下文件的个数
        if (currentIndex.row() == (currentFolderTotal - 1))                //判断是不是最后一个，是就跳出该文件夹
        {
        QModelIndex jumpIndexParent = dirsTree->indexBelow(currentIndex);                //获得跳出的索引
        dirsTree->setCurrentIndex(jumpIndexParent);
        }
        else
        {
        if(nextFlag)
        {
            dirsTree->setCurrentIndex(currentIndex);
            nextFlag = false;
        }
        else
        {
            QModelIndex nextIndex = dirsTree->indexBelow(currentIndex);
            dirsTree->setCurrentIndex(nextIndex);
            nextFlag = false;
        }
        }
}

刚开始用QTreeView不熟悉，昨天找到了indexBelow（），indexAbove（）这两个函数已经实现了。我做的这个是遇到文件夹就打开它dirsTree->setExpanded(currentIndex, 1)，进入这个文件夹，到末尾跳出到下一级，一直一级一级向下走。