How can I set the line style of a specific cell in a QTableView?

Question

I am working with a QT GUI. I am implementing a simple hex edit control using a QTableView. My initial idea is to use a table with seventeen columns. Each row of the table will have 16 hex bytes and then an ASCII representation of that data in the seventeenth column. Ideally, I would like to edit/set the style of the seventeenth column to have no lines on the top and bottom of each cell to give the text a free flowing appearance. What is the best way to approach this using the QTableView?

Answer 1

I could think about a couple of ways of doing what you need; both would include drawing custom grid as it looks like there is no straight forward way of hooking into the grid painting routine of QTableView class:

1.Switch off the standard grid for your treeview grid by calling setShowGrid(false) and draw grid lines for cells which need them using item delegate. Below is an example:

// custom item delegate to draw grid lines around cells
class CustomDelegate : public QStyledItemDelegate
{
public:
    CustomDelegate(QTableView* tableView);
protected:
    void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const;
private:
    QPen _gridPen;
};

CustomDelegate::CustomDelegate(QTableView* tableView)
{
    // create grid pen
    int gridHint = tableView->style()->styleHint(QStyle::SH_Table_GridLineColor, new QStyleOptionViewItemV4());
    QColor gridColor = static_cast<QRgb>(gridHint);
    _gridPen = QPen(gridColor, 0, tableView->gridStyle());
}

void CustomDelegate::paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const
{
    QStyledItemDelegate::paint(painter, option, index);

    QPen oldPen = painter->pen();
    painter->setPen(_gridPen);

    // paint vertical lines
    painter->drawLine(option.rect.topRight(), option.rect.bottomRight());
    // paint horizontal lines 
    if (index.column()!=1) //<-- check if column need horizontal grid lines
        painter->drawLine(option.rect.bottomLeft(), option.rect.bottomRight());

    painter->setPen(oldPen);
}

// set up for your tree view:
ui->tableView->setShowGrid(false);
ui->tableView->setItemDelegate(new CustomDelegate(ui->tableView));

2.Create a QTableView descendant and override the paintEvent method. There you could either draw your own grid or let base class to draw it and then paint horizontal lines on top of the grid with using tableview's background color.

hope this helps, regards