text: /****************************************************************************
  **
  ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
  ** Contact: http://www.qt-project.org/legal
  **
  ** This file is part of the QtGui module of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:LGPL$
  ** 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 Digia.  For licensing terms and
  ** conditions see http://qt.digia.com/licensing.  For further information
  ** use the contact form at http://qt.digia.com/contact-us.
  **
  ** 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
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  ** 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
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  ****************************************************************************/
  
  #ifndef QOPENGLGRADIENTCACHE_P_H
  #define QOPENGLGRADIENTCACHE_P_H
  
  //
  //  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 <private/qopenglcontext_p.h>
  #include <QtCore/qmutex.h>
  #include <QGradient>
  
  QT_BEGIN_NAMESPACE
  
  class QOpenGL2GradientCache : public QOpenGLSharedResource
  {
      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> QOpenGLGradientColorTableHash;
  
  public:
      static QOpenGL2GradientCache *cacheForContext(QOpenGLContext *context);
  
      QOpenGL2GradientCache(QOpenGLContext *);
      ~QOpenGL2GradientCache();
  
      GLuint getBuffer(const QGradient &gradient, qreal opacity);
      inline int paletteSize() const { return 1024; }
  
      void invalidateResource();
      void freeResource(QOpenGLContext *ctx);
  
  private:
      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();
  
      QOpenGLGradientColorTableHash cache;
      QMutex m_mutex;
  };
  
  QT_END_NAMESPACE
  
  #endif // QOPENGLGRADIENTCACHE_P_H
  