/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtOpenGL module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at http://www.qtsoftware.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include <QMultiHash>
#include <QObject>
#include <QtOpenGL/QtOpenGL>

QT_BEGIN_NAMESPACE

class QGL2GradientCache : public QObject
{
    Q_OBJECT
    struct CacheInfo
    {
        inline CacheInfo(QGradientStops s, qreal op, QGradient::InterpolationMode mode) :
            stops(s), opacity(op), interpolationMode(mode) {}

        GLuint texId;
        QGradientStops stops;
        qreal opacity;
        QGradient::InterpolationMode interpolationMode;
    };

    typedef QMultiHash<quint64, CacheInfo> QGLGradientColorTableHash;

public:
    QGL2GradientCache() : QObject(), buffer_ctx(0)
    {
/*
        connect(QGLSignalProxy::instance(),
                SIGNAL(aboutToDestroyContext(const QGLContext *)),
                SLOT(cleanupGLContextRefs(const QGLContext *)));
*/
    }

    GLuint getBuffer(const QGradient &gradient, qreal opacity, const QGLContext *ctx);
    inline int paletteSize() const { return 1024; }

protected:
    inline int maxCacheSize() const { return 60; }
    inline void generateGradientColorTable(const QGradient& gradient,
                                           uint *colorTable,
                                           int size, qreal opacity) const;
    GLuint addCacheElement(quint64 hash_val, const QGradient &gradient, qreal opacity);

    void cleanCache();

    QGLGradientColorTableHash cache;
    const QGLContext *buffer_ctx;

public slots:
    void cleanupGLContextRefs(const QGLContext *context) {
        if (context == buffer_ctx) {
            cleanCache();
            buffer_ctx = 0;
        }
    }
};

QT_END_NAMESPACE