Custom Proxy Example

 /****************************************************************************
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the Qt Data Visualization module of the Qt Toolkit.
 **
 ** $QT_BEGIN_LICENSE:GPL$
 ** Commercial License Usage
 ** Licensees holding valid commercial Qt licenses may use this file in
 ** accordance with the commercial license agreement provided with the
 ** Software or, alternatively, in accordance with the terms contained in
 ** a written agreement between you and The Qt Company. For licensing terms
 ** and conditions see https://www.qt.io/terms-conditions. For further
 ** information use the contact form at https://www.qt.io/contact-us.
 **
 ** GNU General Public License Usage
 ** Alternatively, this file may be used under the terms of the GNU
 ** General Public License version 3 or (at your option) any later version
 ** approved by the KDE Free Qt Foundation. The licenses are as published by
 ** the Free Software Foundation and appearing in the file LICENSE.GPL3
 ** included in the packaging of this file. Please review the following
 ** information to ensure the GNU General Public License requirements will
 ** be met: https://www.gnu.org/licenses/gpl-3.0.html.
 **
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

 #ifndef VARIANTBARDATAMAPPING_H
 #define VARIANTBARDATAMAPPING_H

 #include <QtCore/QObject>
 #include <QtCore/QStringList>

 class VariantBarDataMapping : public QObject
 {
     Q_OBJECT
     Q_PROPERTY(int rowIndex READ rowIndex WRITE setRowIndex)
     Q_PROPERTY(int columnIndex READ columnIndex WRITE setColumnIndex)
     Q_PROPERTY(int valueIndex READ valueIndex WRITE setValueIndex)
     Q_PROPERTY(QStringList rowCategories READ rowCategories WRITE setRowCategories)
     Q_PROPERTY(QStringList columnCategories READ columnCategories WRITE setColumnCategories)
 public:
     explicit VariantBarDataMapping();
     VariantBarDataMapping(const VariantBarDataMapping &other);
     VariantBarDataMapping(int rowIndex, int columnIndex, int valueIndex,
                            const QStringList &rowCategories,
                            const QStringList &columnCategories);
     virtual ~VariantBarDataMapping();

     VariantBarDataMapping &operator=(const VariantBarDataMapping &other);

     void setRowIndex(int index);
     int rowIndex() const;
     void setColumnIndex(int index);
     int columnIndex() const;
     void setValueIndex(int index);
     int valueIndex() const;

     void setRowCategories(const QStringList &categories);
     const QStringList &rowCategories() const;
     void setColumnCategories(const QStringList &categories);
     const QStringList &columnCategories() const;

     void remap(int rowIndex, int columnIndex, int valueIndex,
                const QStringList &rowCategories,
                const QStringList &columnCategories);
 Q_SIGNALS:
     void mappingChanged();

 private:
     // Indexes of the mapped items in the VariantDataItem
     int m_rowIndex;
     int m_columnIndex;
     int m_valueIndex;

     // For row/column items, sort items into these categories. Other categories are ignored.
     QStringList m_rowCategories;
     QStringList m_columnCategories;
 };

 #endif