qgsmaprenderercache.h

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/***************************************************************************
  qgsmaprenderercache.h
  --------------------------------------
  Date                 : December 2013
  Copyright            : (C) 2013 by Martin Dobias
  Email                : wonder dot sk at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSMAPRENDERERCACHE_H
#define QGSMAPRENDERERCACHE_H

#include "qgis_core.h"
#include <QMap>
#include <QImage>
#include <QMutex>

#include "qgsrectangle.h"
#include "qgsmaplayer.h"


class CORE_EXPORT QgsMapRendererCache : public QObject
{
    Q_OBJECT
  public:

    QgsMapRendererCache();

    void clear();

    bool init( const QgsRectangle &extent, double scale );

    void setCacheImage( const QString &cacheKey, const QImage &image, const QList< QgsMapLayer * > &dependentLayers = QList< QgsMapLayer * >() );

    bool hasCacheImage( const QString &cacheKey ) const;

    QImage cacheImage( const QString &cacheKey ) const;

    QList< QgsMapLayer * > dependentLayers( const QString &cacheKey ) const;

    void clearCacheImage( const QString &cacheKey );

  private slots:
    void layerRequestedRepaint();

  private:

    struct CacheParameters
    {
      QImage cachedImage;
      QgsWeakMapLayerPointerList dependentLayers;
    };

    void clearInternal();

    void dropUnusedConnections();

    QSet< QgsWeakMapLayerPointer > dependentLayers() const;

    mutable QMutex mMutex;
    QgsRectangle mExtent;
    double mScale = 0;

    QMap<QString, CacheParameters> mCachedImages;
    QSet< QgsWeakMapLayerPointer > mConnectedLayers;
};


#endif // QGSMAPRENDERERCACHE_H