sort qtreewidget toplevel item base on a child data

Question

i have a qtreewidget with toplevelitems. each toplevelitem has 4 childeren, each child has special value, first child of all toplevelitems is its parrent cost, i want to sort this toplevelitems base on this cost, but i don't know how to do this? my idea is to keep this toplevelitems and their cost in a map and add and take them each time a toplevelitem is added, but i'm looking for a better way. thanks in advance.

Answer 1

By default, tree widget sorts items according to their texts, however you can change it by overriding the operator<() of the QTreeWidgetItem. Below is the example of custom QTreeWidgetItem with specific operator (see comments):

class TreeWidgetItem : public QTreeWidgetItem
{
public:
    // The constructors. Add more, if needed.
    TreeWidgetItem(QTreeWidget *parent, const QStringList &strings,
                   int type = Type)
        : QTreeWidgetItem(parent, strings, type)
    {}

    TreeWidgetItem(QTreeWidgetItem *parent, const QStringList &strings,
                   int type = Type)
        : QTreeWidgetItem(parent, strings, type)
    {}

    // Compares two tree widget items. The logic can be changed.
    bool operator<(const QTreeWidgetItem& other) const
    {
        // Get the price - the first child node
        int price1 = 0;
        if (childCount() > 0)
        {
            QTreeWidgetItem *firstChild = child(0);
            price1 = firstChild->text(0).toInt();
        }

        // Get the second price - the first child node
        int price2 = 0;
        if (other.childCount() > 0)
        {
            QTreeWidgetItem *firstChild = other.child(0);
            price2 = firstChild->text(0).toInt();
        }
        // Compare two prices.
        return price1 < price2;
    }
};

And here is how this class can be used with QTreeWidget:

// The sortable tree widget.
QTreeWidget tw;
tw.setSortingEnabled(true);
QTreeWidgetItem *item1 = new TreeWidgetItem(&tw, QStringList() << "Item1");
QTreeWidgetItem *child1 = new TreeWidgetItem(item1, QStringList() << "10");

QTreeWidgetItem *item2 = new TreeWidgetItem(&tw, QStringList() << "Item2");
QTreeWidgetItem *child2 = new TreeWidgetItem(item2, QStringList() << "11");    
tw.show();