QStyledItemDelegate with paint() and rowColor from Qt::BackgroundColorRole

gde23

Hello,
I have a QStyledItemDelegate with the following implementation of paint()

void MyDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
    const QModelIndex &index) const
{
    .... here the editor is generated and so on
    ....
    ....

    // now the painting part begins
    QStyleOptionViewItem option_widget = option;
    QStyledItemDelegate::initStyleOption(&option_widget, index);

    // where to set the color???
    QColor background = index.model()->data(index, Qt::BackgroundColorRole).value<QColor>();

    // this is needed so the selection is painted correctly, otherwise the row-selection is not visible
    QStyleOptionViewItem option_widget_backgrund = option;
    QStyledItemDelegate::paint(painter, option_widget_backgrund, QModelIndex());

    // start drawing ------------------------------------------------------------
    painter->save();
    editor->setPalette(option_widget.palette);
    editor->resize(option_widget.rect.size());
    painter->translate(option_widget.rect.topLeft());
    editor->render(painter, QPoint(), QRegion(), QWidget::DrawChildren);
    painter->restore();
}

What I am doing here is first call QStyledItemDelegate::paint(painter, option_widget_backgrund, QModelIndex()); with an invalid index to paint the selection background.
This works but is it really the correct way to paint the selection coloring??

Now besides the selection coloring I want to colour the background of some rows as specified by Qt::BackgroundColorRole in the model.
Where do I set this color?

Christian Ehrlicher

QModelIndex has a data() function: https://doc.qt.io/qt-5/qmodelindex.html#data

gde23

@Christian-Ehrlicher: but what do I do with the color data? My problem is that I do not know where to set it.

Christian Ehrlicher

Setting data in the model can be done with QAbstractItemModel::setData()

gde23

Maybe I have not explained clearly what my problem is.

I already have all the data in the model and I also have implemented the setData() and data() functions and so on.
However now I want to have an QStyledItemDelegate in my View that has a custom paint() function.

From the model I get the background color for each item with data(index, Qt::BackgroundColorRole)
When I do not use delegates it also paints the color correctly.
I just do not know how to use the color for the background in my custom paint() function.

VRonin

You don't really have a custom paint. You are just delegating the paint to a widget (editor->render()). You need to set up said widget to support changing its background