Using QTreeView, how to highlight only specific row/colum with calling function?

Question

I am using C++ Qt5. Currently I have a QStandardItemModel being displayed as a QTreeView with multiple rows and columns. I am aware of using setStyleSheet(), but the issue there is that every row and column that the mouse hovers is highlighted.

I would only like specific rows of the first column to be highlighted, and then have a function called for each cell highlighted that I would then use to manipulate my game.

Answer 1

The solution for a personalized painting is to use a custom delegate, and to indicate which item should change the color a role should be used, in the following code I show an example:

#include <QApplication>
#include <QStandardItemModel>
#include <QStyledItemDelegate>
#include <QTreeView>

class StyledItemDelegate: public QStyledItemDelegate{
public:
    using QStyledItemDelegate::QStyledItemDelegate;
protected:
    void initStyleOption(QStyleOptionViewItem *option, const QModelIndex &index) const{
        QStyledItemDelegate::initStyleOption(option, index);
        if(index.data(Qt::UserRole +1).toBool())
            option->backgroundBrush = QBrush(Qt::red);
    }
};


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QTreeView w;
    StyledItemDelegate delegate(&w);
    w.setItemDelegate(&delegate);

    QStandardItemModel model;
    model.setColumnCount(4);
    w.setModel(&model);

    for(int i=0; i<4; i++){
        auto it = new QStandardItem(QString::number(i));
        model.appendRow(it);
        for(int j=0; j<3; j++){
            it->appendRow(new QStandardItem(QString("%1-%2").arg(i).arg(j)));
        }
    }
    QObject::connect(&w, &QTreeView::clicked, [&](const QModelIndex & index){
        bool last_state = model.data(index, Qt::UserRole +1).toBool();
        model.setData(index, !last_state, Qt::UserRole +1);
    });
    w.expandAll();
    w.show();
    return a.exec();
}