QItemDelegate for drawing progress bar working, but won't move off origin

[evankirkiles]

I'm trying to display a QStyleOptionProgressBar in a cell in a QTreeWidget, like the tutorial found here for the Qt torrent client. The progress bar renders, but it is stuck on the very top left of my QTreeWidget item. My guess is that there is no margin for my QTreeWidget so the drawControl function has nothing to offset the coordinates from and so just draws on the origin, but I have no idea what steps to take to remedy this.

Code below:

// HEADER FILE (joblist.hpp)
class JobInterfaceDelegate : public QItemDelegate {
    Q_OBJECT
public:
    inline explicit JobInterfaceDelegate(QWidget* parent=nullptr) : QItemDelegate(parent) {}
    // Render the progress bar
    void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const override;
};

// Interface on which jobs are displayed
class JobInterface : public QTreeWidget {
    Q_OBJECT
public:
    explicit JobInterface(QWidget* parent=nullptr);
};

// SOURCE FILE (joblist.cpp)
// Delegate render method for painting progress bars
void JobInterfaceDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
                                 const QModelIndex &index) const {
    // Only work for fourth column
    if (index.column() != 3) {
        QItemDelegate::paint(painter, option, index);
        return;
    }

    // Set up a QStyleOptionProgressBar to mimic a progress bar
    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;

    // Set the progress and text values of the bar
    // TODO: Reference the job at the column and its progress
    int progress = 25;
    progressBarOption.progress = progress < 0 ? 0 : progress;
    progressBarOption.text = QString::asprintf("%d%%", progressBarOption.progress);
//    progressBarOption.rect = QRect(150, 150, 100, 100);  <- this appears no different from the line below
//    progressBarOption.rect = QRect(100, 100, 100, 100);

    // Draw the progress bar onto the view (THIS IS BROKEN)
    QApplication::style()->drawControl(QStyle::CE_ProgressBar, &progressBarOption, painter);
//    painter->fillRect(option.rect, option.palette.highlight()); <-THIS WORKS
}

// Build an empty job list (tree widget)
JobInterface::JobInterface(QWidget *parent) :
        QTreeWidget(parent) {

    // Build static strings for each column header
    QStringList headers;
    headers << tr("Direction") << tr("Job") << tr("Status") << tr("Progress") << tr("Size")
            << tr("Files") << tr("Transfer Rate") << tr("Elapsed Time");

    // Set all initialization settings
    setItemDelegate(new JobInterfaceDelegate(this));
    setHeaderLabels(headers);
    setSelectionBehavior(QAbstractItemView::SelectRows);
    setAlternatingRowColors(true);
    setRootIsDecorated(false);
    
    // Size hints for columns
    QFontMetrics fm = parent->fontMetrics();
    QHeaderView *hdr = header();
    hdr->setStretchLastSection(false);
    hdr->resizeSection(0, fm.horizontalAdvance("Download      "));
    hdr->setSectionResizeMode(1, QHeaderView::ResizeMode::Stretch);
    hdr->resizeSection(2, fm.horizontalAdvance("Completed      "));
    hdr->resizeSection(3, qMax(fm.horizontalAdvance(headers.at(3) + " "), fm.horizontalAdvance(" 1234.0 KB/s ")));
    hdr->resizeSection(4, fm.horizontalAdvance("100.0 MB / 100.0 MB"));
    hdr->resizeSection(5, fm.horizontalAdvance("100 / 100"));
    hdr->resizeSection(6, qMax(fm.horizontalAdvance(headers.at(3) + " "), fm.horizontalAdvance(" 1234.0 KB/s ")));
    hdr->resizeSection(7, fm.horizontalAdvance(headers.at(7) + " "));
}

The outcome looks like this, where 3 progress bars are stacked on top of each other on the origin (one created for each row):

I want them to be located in the progress bar, each on its own row (obviously).

All help is appreciated!
Evan

[SGaist]

Hi,

Can you check again using QStyledItemDelegate as base class of your delegate ?

[evankirkiles]

@sgaist Yes, same issue unfortunately. :(

[SGaist]

Check the option rect value that you get. If the coordinates don't change, one thing you can do is to update the top left corner based on the row and column number.

[evankirkiles]

Yup, that does it, although kind of a hack. Added painter->translate(option.rect.left(), option.rect.top()) before the drawControl and painter->resetTransform() after it, for anyone who may have this problem in the future. Also made sure to change the rect of the progress bar so its coordinates are (0, 0) just in case the issue isn't consistent across platforms.

Thank you!!!

[SGaist]

Another option you have is to save the state of the painter before you modify it and then restore it.

That way you don't complete reset the transformation if any other was applied before your translation.