QtComboBoxWithTreeView.h

#ifndef QTCOMBOBOXWITHTREEVIEW_H
#define QTCOMBOBOXWITHTREEVIEW_H

#include <QComboBox>
#include <QMouseEvent>
#include <QModelIndex>
#include <QAbstractItemView>
#include <QTreeView>
#include <QApplication>

/*
 * From the hack provided in below url:
 * http://www.developer.nokia.com/Community/Wiki/Implementing_QTreeView_in_QComboBox_using_Qt-_Part_2
 *
 * There are some bugs being worked on. Hopefully patch will reach Qt5
 * and we can remove this file.
 * https://bugreports.qt-project.org/browse/QTBUG-11660
 * https://codereview.qt-project.org/#change,16716
 */

class QtComboBoxWithTreeView : public QComboBox {
  Q_OBJECT
 public:
  explicit QtComboBoxWithTreeView(QWidget* parent = 0) : QComboBox(parent), skipNextHide(false) {
    QTreeView* view = new QTreeView(this);
    view->setHeaderHidden(true);
    setView(view);
    view->viewport()->installEventFilter(this);
  }

  bool eventFilter(QObject* object, QEvent* event) {
    if (event->type() == QEvent::MouseButtonPress && object == view()->viewport()) {
      QMouseEvent* mouseEvent = static_cast<QMouseEvent*>(event);
      QModelIndex index = view()->indexAt(mouseEvent->pos());
      if (!view()->visualRect(index).contains(mouseEvent->pos())) skipNextHide = true;
    }
    return false;
  }

  virtual void hidePopup() {
    if (skipNextHide) {
      skipNextHide = false;
      /*
       * We are doing a big hack here.
       * This is done in order to expand/shrink the popup
       * as trees expand/shrink
       */
      bool old = QApplication::isEffectEnabled(Qt::UI_AnimateCombo);
      if (old) QApplication::setEffectEnabled(Qt::UI_AnimateCombo, false);
      QComboBox::hidePopup();
      QComboBox::showPopup();
      if (old) QApplication::setEffectEnabled(Qt::UI_AnimateCombo, true);
    } else
      QComboBox::hidePopup();
  }

 private:
  bool skipNextHide;
};

#endif  // QTCOMBOBOXWITHTREEVIEW_H