TileCache.h

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#ifndef OSMSCOUT_CLIENT_QT_TILECACHE_H
#define OSMSCOUT_CLIENT_QT_TILECACHE_H

/*
 OSMScout - a Qt backend for libosmscout and libosmscout-map
 Copyright (C) 2016  Lukas Karas

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 */


#include <QObject>
#include <QString>
#include <QMetaType>
#include <QMutex>
#include <QHash>
#include <QMap>
#include <QSet>
#include <QTime>
#include <QElapsedTimer>
#include <QImage>
#include <QPixmap>
#include <QDebug>

#include <osmscout/util/GeoBox.h>
#include <osmscout/ClientQtImportExport.h>

//#define DEBUG_TILE_CACHE

namespace osmscout {

struct TileCacheKey
{
    uint32_t zoomLevel;
    uint32_t xtile;
    uint32_t ytile;
};

bool operator==(const TileCacheKey &a, const TileCacheKey &b);

bool operator<(const TileCacheKey &a, const TileCacheKey &b);

uint qHash(const TileCacheKey &key);

QDebug& operator<<(QDebug &out, const TileCacheKey &key);

struct TileCacheVal
{
  QElapsedTimer lastAccess;
  QPixmap image;
  size_t epoch;
};

struct RequestState
{
    bool pending; 
};

class OSMSCOUT_CLIENT_QT_API TileCache : public QObject
{
  Q_OBJECT

signals:
  void tileRequested(uint32_t zoomLevel, uint32_t x, uint32_t y);

public:
  TileCache(size_t cacheSize);
  ~TileCache() override;

  void clearPendingRequests();
  bool startRequestProcess(uint32_t zoomLevel, uint32_t x, uint32_t y);
  void mergeAndStartRequests(uint32_t zoomLevel, uint32_t xtile, uint32_t ytile,
    uint32_t &xFrom, uint32_t &xTo, uint32_t &yFrom, uint32_t &yTo, uint32_t maxWidth, uint32_t maxHeight);
  bool isRequestQueueEmpty() const;

  bool request(uint32_t zoomLevel, uint32_t x, uint32_t y);

  bool reemitRequests();
  bool contains(uint32_t zoomLevel, uint32_t x, uint32_t y);
  bool containsRequest(uint32_t zoomLevel, uint32_t x, uint32_t y);
  TileCacheVal get(uint32_t zoomLevel, uint32_t x, uint32_t y);

  bool invalidate(osmscout::GeoBox box = osmscout::GeoBox());

  bool removeRequest(uint32_t zoomLevel, uint32_t x, uint32_t y);
  void put(uint32_t zoomLevel, uint32_t x, uint32_t y, QImage image, size_t epoch = 0);

  void cleanupCache();

  inline size_t getEpoch() const
  {
    return epoch;
  }

  inline void incEpoch()
  {
    epoch ++;
  }

private:
  QHash<TileCacheKey, TileCacheVal> tiles;
  QHash<TileCacheKey, RequestState> requests;
  size_t                            cacheSize; // maximum count of elements in cache
  uint32_t                          maximumLivetimeMs;
  size_t                            epoch{0};
};

}

Q_DECLARE_METATYPE(osmscout::TileCacheKey)
Q_DECLARE_METATYPE(osmscout::TileCacheVal)
Q_DECLARE_METATYPE(osmscout::RequestState)

#endif  /* OSMSCOUT_CLIENT_QT_TILECACHE_H */