How to display marquee animation of QProgressBar properly when using it in QTreeView

[Infinity]

You are right, "constantly" doesn't make sense.

the progress bar animated regardless if it changes its values or not

I haven't thought of that yet because I don't use Windows so often.

Maybe I can reduce that problem by hiding progress bars that aren't visible. I will try it and test it on Windows.

[wysota]

I haven't thought of that yet because I don't use Windows so often.

Neither do I but my students had to deal with the animated progress bar problem back in Qt 4.4-ish days. I don't think much has changed since then in this regard.

Maybe I can reduce that problem by hiding progress bars that aren't visible. I will try it and test it on Windows.

I think you should first think if you really need to update all those bars "constantly" as this seems to me like a bigger problem than Windows redrawing progress bars (you can always draw a progress bar yourself in the delegate to overcome this issue).

[Infinity]

I tested the application under Windows. There are no performance problems, but the CPU usage is higher. I think the animation (which I don't really need) is not worth it considering the higher CPU usage.

As already mentioned I'm also displaying QComboBoxes in another column. Currently I'm using openPersistentEditor() to display them. Now I've tried to display them by manual painting:

void ComboBoxItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const//(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QStyleOptionComboBox comboBoxOption;
    comboBoxOption.rect = option.rect;
    comboBoxOption.state = option.state;
    comboBoxOption.state |= QStyle::State_Enabled;
    comboBoxOption.state |= QStyle::State_On;
    comboBoxOption.subControls = QStyle::SC_All;
    comboBoxOption.editable = false;
    comboBoxOption.currentText = index.model()->data(index).toString();
 
    QApplication::style()->drawComplexControl(QStyle::CC_ComboBox, &comboBoxOption, painter);
    QApplication::style()->drawControl(QStyle::CE_ComboBoxLabel, &comboBoxOption, painter);
}

void ComboBoxItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const//(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QStyleOptionComboBox comboBoxOption;
    comboBoxOption.rect = option.rect;
    comboBoxOption.state = option.state;
    comboBoxOption.state |= QStyle::State_Enabled;
    comboBoxOption.state |= QStyle::State_On;
    comboBoxOption.subControls = QStyle::SC_All;
    comboBoxOption.editable = false;
    comboBoxOption.currentText = index.model()->data(index).toString();

    QApplication::style()->drawComplexControl(QStyle::CC_ComboBox, &comboBoxOption, painter);
    QApplication::style()->drawControl(QStyle::CE_ComboBoxLabel, &comboBoxOption, painter);
}

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On Windows the code works, but on Linux (when using QGtkStyle) I'm just getting the ComboBoxLabel. Does anybody know why painting the combo box not works with QGtkStyle?

[wysota]

Drawing a combobox is one thing. Making it work like a combobox is another. If you want to hear my personal opinion then pushing comboboxes into table columns is a violation against user experience If you consider what the column contains -- it contains some VALUE. The way you change the value and the sole fact that you can change the value (or not) is meaningless while displaying that value. If you display a bunch of comboboxes in a column, you just clutter the display and you have no functional benefit over just displaying the value contained in the field. If the user wants to edit a field, he will enter edit mode and use the combo that pops up, to modify the value which afterwards will again be displayed in the column.