How to update progress bar in delegate?

SRaD

I have a TreeViewDelegate that is derived from QStyledItemDelegate. In this view, in a specific row and column I have a progress bar that now appears but, I'm not clear on how to update the progress bar from outside the delegate.

Can anyone offer some advice?

void MyTreeViewDelegate::paint(QPainter *painter,
    const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QModelIndex parent = index.parent();

    if (parent.row() < 0) {
        if (index.column() == 1 && index.row() == 1) {
            QStyleOptionProgressBar progressBarOption;
            progressBarOption.state = QStyle::State_Enabled;
            progressBarOption.direction = QApplication::layoutDirection();
            progressBarOption.rect = option.rect;
            progressBarOption.fontMetrics = QApplication::fontMetrics();
            progressBarOption.minimum = 0;
            progressBarOption.maximum = 100;
            progressBarOption.textAlignment = Qt::AlignCenter;
            progressBarOption.textVisible = true;

            bool is_number;

            int progress = index.data(Qt::DisplayRole).toInt(&is_number);

            if (is_number)
                progressBarOption.progress = progress < 0 ? 0 : progress;

            progressBarOption.text = QString::asprintf("%d%% Complete",
                progressBarOption.progress);

            QApplication::style()->drawControl(QStyle::CE_ProgressBar,
                &progressBarOption, painter);
        }
    }

    QStyledItemDelegate::paint(painter, option, index);

    return;
}

SGaist

Hi,

If you properly call dataChanged when modifying your model content, your progress bars should be updated automatically.

SRaD

I guess I'm not clear on how that works. I now have the following ...

void MyTreeViewDelegate::paint(QPainter *painter,
    const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QModelIndex parent = index.parent();

    if (parent.row() < 0) {
        if (index.column() == 1 && index.row() == 1) {
            QStyleOptionProgressBar progressBarOption;
            progressBarOption.state = QStyle::State_Enabled;
            progressBarOption.direction = QApplication::layoutDirection();
            progressBarOption.rect = option.rect;
            progressBarOption.fontMetrics = QApplication::fontMetrics();
            progressBarOption.minimum = 0;
            progressBarOption.maximum = 100;
            progressBarOption.textAlignment = Qt::AlignCenter;
            progressBarOption.textVisible = true;

            int progress = cars_processed;

            progressBarOption.progress = progress < 0 ? 0 : progress;

            progressBarOption.text = QString::asprintf("%d%% Complete",
                progressBarOption.progress);

            QApplication::style()->drawControl(QStyle::CE_ProgressBar,
                &progressBarOption, painter);
        }
    }

    QStyledItemDelegate::paint(painter, option, index);

    return;
}

And say I have 100 cars. So in my MainWindow I have this ...

for (auto& car : cars) {
    ++cars_processed;
}

As I increment the number of cars_processed, how do I immediately tell the paint function above to update the progress bar?

SGaist

As already suggested: you have to update your model content and ensure that dataChanged is called.

Then, if you are updating your model in a tight loop, you might not see updates on your GUI because you are blocking the event loop.