disable the Icon (decoration role) of the QStandardItems on for certain QTreeView?

[mbruel]

Hello,
I'm having a main View that display my Model with icons on my items and I'd like to display a part of it on another view but without the icons.
Would this be possible?
Could I tell the view to not go for the decoration?

[VRonin]

It's not the view, it's the delegate but sure you can

WARNING: wrong code, see below

class NoIconDelegate : public QStyledItemDelegate{
Q_OBJECT
Q_DISABLE_COPY(NoIconDelegate)
public:
exclicit NoIconDelegate(QObject* parent=Q_NULLPTR) : QStyledItemDelegate(parent){}
void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE{
 Q_ASSERT(index.isValid());
    QStyleOptionViewItem opt = option;
    initStyleOption(&opt, index);
opt.icon = QIcon();
opt.decorationSize=QSize(-1, -1);
opt.features &= ~QStyleOptionViewItem::HasDecoration;
    QStyle *style = option.widget ? option.widget->style() : QApplication::style();
style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, option.widget);
}
}

[mbruel]

Cheers,
It makes sense that it is the delegate and not the view directly that does the job!
Thanks

[VRonin]

@mbruel On second thought, this is much better, it is more effivcient and also impacts sizeHint:

class NoIconDelegate : public QStyledItemDelegate{
    Q_OBJECT
    Q_DISABLE_COPY(NoIconDelegate)
public:
    explicit NoIconDelegate(QObject* parent=Q_NULLPTR) : QStyledItemDelegate(parent){}
protected:
    void initStyleOption(QStyleOptionViewItem *option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QVariant value = index.data(Qt::FontRole);
        if (value.isValid() && !value.isNull()) {
            option->font = qvariant_cast<QFont>(value).resolve(option->font);
            option->fontMetrics = QFontMetrics(option->font);
        }
        value = index.data(Qt::TextAlignmentRole);
        if (value.isValid() && !value.isNull())
            option->displayAlignment = Qt::Alignment(value.toInt());
        value = index.data(Qt::ForegroundRole);
        if (value.canConvert<QBrush>())
            option->palette.setBrush(QPalette::Text, qvariant_cast<QBrush>(value));
        option->index = index;
        value = index.data(Qt::CheckStateRole);
        if (value.isValid() && !value.isNull()) {
            option->features |= QStyleOptionViewItem::HasCheckIndicator;
            option->checkState = static_cast<Qt::CheckState>(value.toInt());
        }
        value = index.data(Qt::DisplayRole);
        if (value.isValid() && !value.isNull()) {
            option->features |= QStyleOptionViewItem::HasDisplay;
            option->text = displayText(value, option->locale);
        }
        option->backgroundBrush = qvariant_cast<QBrush>(index.data(Qt::BackgroundRole));
        option->styleObject = 0;
    }
};

[mbruel]

@VRonin

cool to use directly the initStyleOption method :)
I'm not sure why you explore so many Roles, this seems to do the job perfectly:

void NoIconTreeItemDelegate::initStyleOption(QStyleOptionViewItem *option, const QModelIndex &index) const
{
    QStyledItemDelegate::initStyleOption(option, index);
    option->icon           = QIcon();
    option->decorationSize = QSize(-1, -1);
    option->features      &= ~QStyleOptionViewItem::HasDecoration;
}

Personnaly I wish to only let the icons for my Root elements so here is my implementation:

void NoIconTreeItemDelegate::initStyleOption(QStyleOptionViewItem *option, const QModelIndex &index) const
{
    QStyledItemDelegate::initStyleOption(option, index);
    TreeItem *item = static_cast<const TreeProxyModel*>(index.model())->itemFromIndex(index);
    if (item && !static_cast<TreeItem*>(item)->isRootItem())
    {
        option->icon           = QIcon();
        option->decorationSize = QSize(-1, -1);
        option->features      &= ~QStyleOptionViewItem::HasDecoration;
    }
}

[VRonin]

@mbruel said in disable the Icon (decoration role) of the QStandardItems on for certain QTreeView?:

I'm not sure why you explore so many Roles

I just copy-pasted the body of QStyledItemDelegate::initStyleOption and removed the part that had to do with the decoration role.

TreeItem *item = static_cast<const TreeProxyModel*>(index.model())->itemFromIndex(index);
    if (item && !static_cast<TreeItem*>(item)->isRootItem())

Using model-specific stuff inside the delegate is bad design. that whole snippet can be replaced with if(!index.parent().isValid()) and be compatible with all models

[mbruel]

@VRonin said in disable the Icon (decoration role) of the QStandardItems on for certain QTreeView?:

Using model-specific stuff inside the delegate is bad design. that whole snippet can be replaced with if(!index.parent().isValid()) and be compatible with all models

Yeah I know but my delegate is completely specialized to the need of my App.

static_cast<TreeItem*>(item)->isRootItem()

is not telling me if the item the root of TreeModel but rather if I should display the item bigger.
I could have several types of Items that I wish to display bigger in my main TreeView. In the other ones where I'll use this delegate with no icon, I will just display the Icon only for those types without making it bigger and not display the icons for the "standard" other items

@VRonin said in disable the Icon (decoration role) of the QStandardItems on for certain QTreeView?:

I just copy-pasted the body of QStyledItemDelegate::initStyleOption and removed the part that had to do with the decoration role.

Ah ok I see. I find it more clear to use the main method and then just override the decoration part.