How to add different types of delegates in QTreeView

Question

I want to create same kind of QTreeView (not QTreeWidget) structure as shown in attached figure.. This is Property Editor of QT. I am using QT-4.6

On 2nd column, depending on different condition, I can have either a spin box, or a drop down or a checkbox or text edit... and so on... Please guide me on how to set different delegates in different cells of a particular column. From docs, it is evident that there is no straight away API for setting delegate on a cell (rather is available for full widget or a row or a column).

If you need literally a property editor, then you could reuse one from Qt Designer. There's another open source Qt-based library that implements generic property sheets with custom editors. I forget its name at the moment. — Kuba hasn't forgotten Monica, Feb 05 '16 at 19:35
@Kubahasn'tforgottenMonica how can I reuse that? any possible way in pyqt? — demberto, Apr 17 '23 at 04:30

score 6 · Accepted Answer · answered Feb 05 '16 at 19:27

All QAbstractItemDelegate methods, like createEditor or paint, have a model index as one of their parameters. You can access model data using that index and create an appropriate delegate widget. When you create your model you should set some value to every item that will be used to distinguish its type.

An example:

enum DelegateType
{
    DT_Text,
    DT_Checkbox,
    DT_Combo
}

const int MyTypeRole = Qt::UserRole + 1;

QStandardItemModel* createModel()
{
    QStandardItemModel *model = new QStandardItemModel;

    QStandardItem *item = new QStandardItem;
    item->setText("Hello!");
    item->setData(DT_Checkbox, MyTypeRole);

    model->appendRow(item);

    return model;
}

QWidget* MyDelegate::createEditor(QWidget *parent, 
                                  const QStyleOptionViewItem &option, 
                                  const QModelIndex &index) const
{
    int type = index.data(MyTypeRole).toInt();

    // this is a simplified example
    switch (type)
    {
    case DT_Text:
        return new QLinedEdit;
    case DT_Checkbox:
        return new QCheckBox;
    case DT_Combo:
        return new QComboBox;
    default:
        return QItemDelegate::createEditor(parent, option, index);
    }
}

One more question: There will be multiple combo boxes on different items.. Now I want different values to be present in different combo boxes.. Example : If there is a combo box for item1 , I want to display the entries as "a" , "b" and "c". For item4, the combo box should have the entries as " d" , "e" , "f" What is the best way to achieve that with above solution you mentioned.? — Nishant Sharma, Feb 06 '16 at 07:23
In that case you should have two different types of comboboxes. For example, you have a font size combo and a font color combo. Each of them will treat raw model data in different way. Let's assume that an item can have raw values "1", "2", "3". Then the first combo should display "small", "medium", "large", and the second one should display "red", "blue", "black". — hank, Feb 06 '16 at 07:52

score 1 · Answer 2 · answered Feb 06 '16 at 08:59

@hank This is in response to your last comment... Do you see any flaw in it ?

   MyItem* item2 = new MyItem(second);
    item2->setData(delType, **MyTypeRole**);
    if(delType == DT_Combo)
    {
        QString str1, str2, str3;
        QStringList abc ;
        abc << ("1" + str1.setNum(counter) ) << ("2" + str2.setNum(counter) )<< ( "3" + str3.setNum(counter) );
        item2->setData(abc, MyTypeRole1);
    }

QWidget* MyDelegate::createEditor(QWidget *parent, 
                                  const QStyleOptionViewItem &option, 
                                  const QModelIndex &index) const
{
    int type = index.data(MyTypeRole).toInt();

    // this is a simplified example
switch (type)
{
case DT_Text:
    return new QLinedEdit;
case DT_Combo:
{
QComboBox* cb = new QComboBox(parent);
QStringList entries - index.data(MyTypeRole1).toStringList();
cb->addItems(entries)
return cb;
}

On different item2, I dynamically create entries with a counter variable that is different everytime it comes here... Here, different combo boxes display different entries.
Does the approach looks fine to you ?

How to add different types of delegates in QTreeView

2 Answers2