How to color or make text bold for particular cell in QTableView?

Question

I have used QTableView to saw tabular data in my Qt program and somehow I need to differentiate some cells from others, can be done making font bold in those particular cells or painting background of those particular cells.

Can someone please provide code rather than just saying use QAbstractItemDelegate ?

I read through documentation of QAbstractItemDelegate but could not understand so please explain using example.

Neurovascular

Answer 1

No need to go with abstract delegate. Styled delegate does most of the work you need. Use it and reimplement only needed behaviour.

.h:

#include <QStyledItemDelegate>

class MyDelegate : public QStyledItemDelegate
{
    Q_OBJECT

    public:
        explicit MyDelegate(QObject *parent = 0);

        void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const;

    private:
        bool shouldBeBold(const QModelIndex &index);
}

.cpp:

MyDelegate::MyDelegate(QObject *parent) :
    QStyledItemDelegate(parent)
{
}


void MyDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QStyleOptionViewItem opt = option;
    initStyleOption(&opt, index);

    QVariant data = index.data(...); // pick the data you need here
    opt.font.setBold(shouldBeBold(data));

    QStyledItemDelegate::paint(painter, opt, index);
}

bool MyDelegate::shouldBeBold(const QModelIndex &index)
{
    // you need to implement this
}

Then apply delegate to the view. If shouldBeBold() returns false, delegate will paint like a standard one. If it returns true, it will apply bold font.

I hope that's enought for you to get started.

Tache

Answer 2

In order to make text appear differently in your table view, you can modify your model, if any exists, and handle Qt::FontRole and/or Qt::ForegroundRole roles in the model's QAbstractItemModel::data() function. For example:

QVariant MyModel::data(const QModelIndex &index, int role) const
{
    if (role == Qt::FontRole && index.column() == 0) { // First column items are bold.
        QFont font;
        font.setBold(true);
        return font;
    } else if (role == Qt::ForegroundRole && index.column() == 0) {
        return QColor(Qt::red);
    } else {
        [..]
    }

}

Urbanite

Hi! How did you know for Qt::ForegroundRole we can return just the QColor? From documentation what I understand is we can return QBrush. The link where I found this information Doc Link The doc states - Qt::ForegroundRole The foreground brush (text color, typically) used for items rendered with the default delegate. (QBrush) – Martinsen

@sami1592, the data() function does not return QColor, but QVariant built with either QColor or QBrush. Whatever it is, it will be finally converted to QBrush with qvariant_cast<QBrush>(). – Urbanite

it will be finally converted to QBrush with qvariant_cast<QBrush>() How do we know this? from the Qt source code? – Martinsen

Yes, I looked in the sources. – Urbanite

This is the correct solution and everybody else is wrong :-) – Arlettearley

Answer 3

If you don't have a model or a delegate and you don't want to create one, you can set the font of the cell directly:

QFont font(cell->font());
font.setBold(true);
cell->setFont(font);

Fortin