CODEWITHSUNDEEP
qtdelegatesqtreeviewqcomboboxqstandarditemmodel
rava
rava

Reputation: 183

QT: How to show combo boxes as cells in a tree view

In a designer-based QT GUI application I'm using a QTreeView to show a tree of elements that is provided by an instance of QStandardItemModel. The tree-view is multi-column and all elements in the first column are checkable. The screenshot shows an example of how this currently looks like: this is how the tree view currently looks like

Now let's say I'd like the user to be able to select different names for "point". The idea is to have a QComboBox right next to each of the checkboxes. And as alternatives to "point" he may chose from a set of strings, e.g. "point", "pt" and "coord2D". Later on I'd like all selections for all duplicates of "point" to be synchronized but let's start simple...

I'm not too familiar with the idea but to me it looks like the way to go is to create an ItemDelegate for the view as described in the QT Documentation or in this topic (both links refer to QTableWidgets instead of QTreeViews).

So what I did as a first step is I took the example delegate ComboBoxDelegate from the stack overflow question mentioned above and called it from within my application using this code also taken from a related question:

QStandardItemModel* model = new QStandardItemModel(20,2);
ui.tvStructures->setModel(model);
ui.tvStructures->setItemDelegate(new ComboBoxDelegate());

for (int row = 0 ; row < 20; ++row)
{
    for (int col = 0; col < 2; ++col)
    {
        QModelIndex index = model->index(row, col, QModelIndex());
        model->setData(index, QVariant((row+1) * (col+1)));
    }
}

Note that I placed this code inside the constructor of the parent QDialog where the control element is located. What I ended up is a 2-column table as expected but without any combo boxes. In fact when debugging the code I observe that the constructor of the delegate is called (during the new operation) but none of createEditor, setEditorData, setModelData or updateEditorGeometry every get called. I thought this may be due to the fact that some connection magic is overwriting triggers required to do the drawing but even if I remove all code that refers to the tvStructures QTreeView apart from what I have posted I still can't see any combo boxes.

What's missing?

Note that I'm using the somewhat outdated QT 4.7.1

Upvotes: 1

Views: 1905

Answers (1)

Felipe Lema
Felipe Lema

Reputation: 2718

Looks like you're missing a parent for new QComboBoxDelegate. You can use the QDialog you mentioned as parent.

Also: follow this lengthy example to make sure you're not missing anything else.

Upvotes: 1

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