Qt, How can I sort QTableWidget column if the cells are widgets

Question

I have a QTableWidget, some columns are filled with text, some with numbers, these columns are fine to sort. But I also have a column with custom widgets, how should I enable sorting for these?

My first thought was of course to overload the '<' method on the QTableWidgetItem, but there are no QTableWidgetItem. So what would be the best way to solve this?

Answer 1

QTableWidget is not ideal for this case, consider using QTableView. Anyway, I will show you how to sort a QProgressBar widget in a QTableWidget.

As you already said, you can overload the <() operator for this case. Let's say you have a QProgressBar in column number 4. You have to overload the <() operator.

You have to subclass QProgressBar and QTableWidgetItem.

class CustomTableWidgetItem : public QProgressBar, public QTableWidgetItem
{
    Q_OBJECT
public:
    CustomTableWidgetItem( QWidget* parent ) : QProgressBar( parent )
    {
    }

    CustomTableWidgetItem(const QString txt = QString("0"))
        :QTableWidgetItem(txt)
    {
    }

    bool operator <(const QTableWidgetItem& other) const
    {
         if(other.column() == 0 /* numeric cell */) {
             return QTableWidgetItem::text().toInt() < other.text().toInt();
         }
         else if(other.column() == 4 /* progress bar */) {
            const QProgressBar *p = dynamic_cast<const QProgressBar *>(&other);
            if(p != 0) {
                if(this->value() < p->value())
                    return true;
            }
        }

        return false;
    }
};

And then you can insert your QProgressBar like this in cell number 4.

Insert QProgressBar like this

ui->tableWidget->insertRow(ui->tableWidget->rowCount());
CustomTableWidgetItem *pgbar = new CustomTableWidgetItem(this);
ui->tableWidget->setCellWidget(ui->tableWidget->rowCount()-1, 4, pgbar);
ui->tableWidget->setItem(ui->tableWidget->rowCount()-1, 4, pgbar);

Let's say you want to have simple text at cell 1 use QTableWidgetItem.

ui->tableWidget->setItem(ui->tableWidget->rowCount()-1, 1, new QTableWidgetItem("Hello"));

If you want to sort numbers as well, for example in cell 0 use CustomTableWidgetItem, since we have implemented an if-statement as you can see above for sorting numbers and progressbar.

ui->tableWidget->setItem(ui->tableWidget->rowCount()-1, 0, new CustomTableWidgetItem(QString::number(ui->tableWidget->rowCount())));

You can use this approach with other widgets as well, just subclass the correct widget, but in general it's better to use QTableView (MVC approach).

Here is a screenshot with QTableWidget and QProgressBar sorting.