[Snippet] QComboBox showing tree models

Hi everyone,

I run into some problems trying to display tree models in a QComboBox lately and I was not able to found a clean solution on Internet.
I finally managed to create a very simple class that is able to display the first column of some tree item model so I thought I could post it here so that it could be useful to someone ^^

Here's the code:

TreeViewComboBox.h

Code:

---

#ifndef TREEVIEWCOMBOBOX_H
#define TREEVIEWCOMBOBOX_H
 
#include <QtGui/QComboBox>
#include <QtGui/QTreeView>
 
class TreeViewComboBox : public QComboBox {
  Q_OBJECT
  QTreeView* _treeView;
public:
  explicit TreeViewComboBox(QWidget *parent = 0);
  virtual void showPopup();
 
public slots:
  void selectIndex(const QModelIndex&);
};
#endif // TREEVIEWCOMBOBOX_H

---

TreeViewComboBox.cpp

Code:

---

#include "TreeViewComboBox.h"
 
#include <QtGui/QHeaderView>
 
TreeViewComboBox::TreeViewComboBox(QWidget *parent): QComboBox(parent), _treeView(NULL) {
  _treeView = new QTreeView(this);
  _treeView->setFrameShape(QFrame::NoFrame);
  _treeView->setEditTriggers(QTreeView::NoEditTriggers);
  _treeView->setAlternatingRowColors(true);
  _treeView->setSelectionBehavior(QTreeView::SelectRows);
  _treeView->setRootIsDecorated(false);
  _treeView->setWordWrap(true);
  _treeView->setAllColumnsShowFocus(true);
  _treeView->header()->setVisible(false);
  setView(_treeView);
}
 
void TreeViewComboBox::showPopup() {
  setRootModelIndex(QModelIndex());
 
  for(int i=1;i<model()->columnCount();++i)
    _treeView->hideColumn(i);
 
  _treeView->expandAll();
  _treeView->setItemsExpandable(false);
  QComboBox::showPopup();
}
 
void TreeViewComboBox::selectIndex(const QModelIndex& index) {
  setRootModelIndex(index.parent());
  setCurrentIndex(index.row());
}

---

The code itself is pretty much self-explanatory and the tree view can be tweaked in various way.

Cheers

EDIT: Since QComboBox's currentIndex property supports only top-level indexes, you can use the selectIndex method to pre-select item from your code.