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.

The solution in these cases is to use a delegate to change the painting and use a role to indicate that this item should be changed, the painting can not be done with qss so the answer for your particular case will depend on how you want to paint. — eyllanesc
I checked it a bit quick. I've worked with this and it doesn't highlight when the mouse hovers over a cell. Thoughts? — Ender
That is another thing, if you read your question does not talk about any special event, so my answer is a general perspective, for example you should detect when the event happens, get the QModelIndex and update the data associated with the role and QModelIndex . — eyllanesc
so I said in my comment of the specific case, so now your task is to discover how to detect the hover event, get the QModelIndex and update the data, if you want a precise answer then ask something precise and not general. — eyllanesc

eyllanesc eyllanesc · Accepted Answer · 2018-10-28T17:52:23

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();
}

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

1 Answers