How to redefine a node expanding in a QTreeWidget?

flammmable

As I can understand the qtreeview.cpp the expand method in the QTreeView is responce for expanding nodes. For example it used in the expandOrCollapseItemAtPos method. I try to redefine a node expantion in the QTreeWidget:

#include <QApplication>
#include <QWidget>
#include <QTreeWidget>
#include <QMessageBox>

class MyTree : public QTreeWidget
{
public:
    MyTree(QWidget *parent) : QTreeWidget(parent) {}
    expandItem(const QTreeWidgetItem *item) {
        QMessageBox msg;
        msg.setText("EXPAND ITEM!!");
        msg.exec();
        QTreeWidget::expandItem(item);
    }
    expand(const QModelIndex &index) {
        QMessageBox msg;
        msg.setText("EXPAND!!");
        msg.exec();
        QTreeWidget::expand(index);
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QWidget *mainWidget = new QWidget();
    mainWidget->resize(200,100);

    MyTree *myTree = new MyTree(mainWidget);
    myTree->resize(200,100);

    QTreeWidgetItem *node, *leaf;
    node = new QTreeWidgetItem(myTree);
    node->setText(0,"node");
    leaf = new QTreeWidgetItem(node);
    leaf->setText(0,"leaf");

    mainWidget->show();
    return a.exec();
}

But there is no any message box when I expand a node. I try to comment QTreeWidget::expandItem(item); and QTreeWidget::expand(index); and expanding still working. How to redefine a node expanding in a QTreeWidget?

Christian Ehrlicher

I don't see where you call expandItem() at all. And since QTreeWidget::expandItem() is not virtual you can't overwrite this function.

flammmable

Thank you! I will use a slot-signal mechanism:

connect(this, SIGNAL(expanded(QModelIndex)), this, SLOT(myExpand(QModelIndex)));