qgssvgcache.h

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/***************************************************************************
                              qgssvgcache.h
                            ------------------------------
  begin                :  2011
  copyright            : (C) 2011 by Marco Hugentobler
  email                : marco dot hugentobler at sourcepole dot ch
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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 QGSSVGCACHE_H
#define QGSSVGCACHE_H

#include <QColor>
#include <QMap>
#include <QMultiHash>
#include <QString>
#include <QUrl>

class QDomElement;
class QImage;
class QPicture;

class CORE_EXPORT QgsSvgCacheEntry
{
  public:
    QgsSvgCacheEntry();
    QgsSvgCacheEntry( const QString& file, double size, double outlineWidth, double widthScaleFactor, double rasterScaleFctor, const QColor& fill, const QColor& outline );
    ~QgsSvgCacheEntry();

    QString file;
    double size; //size in pixels (cast to int for QImage)
    double outlineWidth;
    double widthScaleFactor;
    double rasterScaleFactor;
    QColor fill;
    QColor outline;
    QImage* image;
    QPicture* picture;
    //content (with params replaced)
    QByteArray svgContent;

    //keep entries on a least, sorted by last access
    QgsSvgCacheEntry* nextEntry;
    QgsSvgCacheEntry* previousEntry;

    bool operator==( const QgsSvgCacheEntry& other ) const;
    int dataSize() const;
};

class CORE_EXPORT QgsSvgCache : public QObject
{
    Q_OBJECT

  public:

    static QgsSvgCache* instance();
    ~QgsSvgCache();

    const QImage& svgAsImage( const QString& file, double size, const QColor& fill, const QColor& outline, double outlineWidth,
                              double widthScaleFactor, double rasterScaleFactor, bool& fitsInCache );
    const QPicture& svgAsPicture( const QString& file, double size, const QColor& fill, const QColor& outline, double outlineWidth,
                                  double widthScaleFactor, double rasterScaleFactor, bool forceVectorOutput = false );

    void containsParams( const QString& path, bool& hasFillParam, QColor& defaultFillColor, bool& hasOutlineParam, QColor& defaultOutlineColor, bool& hasOutlineWidthParam,
                         double& defaultOutlineWidth ) const;

    QByteArray getImageData( const QString &path ) const;

  signals:
    void statusChanged( const QString&  theStatusQString );

  protected:
    QgsSvgCache( QObject * parent = 0 );

    QgsSvgCacheEntry* insertSVG( const QString& file, double size, const QColor& fill, const QColor& outline, double outlineWidth,
                                 double widthScaleFactor, double rasterScaleFactor );

    void replaceParamsAndCacheSvg( QgsSvgCacheEntry* entry );
    void cacheImage( QgsSvgCacheEntry* entry );
    void cachePicture( QgsSvgCacheEntry* entry, bool forceVectorOutput = false );
    QgsSvgCacheEntry* cacheEntry( const QString& file, double size, const QColor& fill, const QColor& outline, double outlineWidth,
                                  double widthScaleFactor, double rasterScaleFactor );

    void trimToMaximumSize();

    //Removes entry from the ordered list (but does not delete the entry itself)
    void takeEntryFromList( QgsSvgCacheEntry* entry );

  private slots:
    void downloadProgress( qint64, qint64 );

  private:
    static QgsSvgCache* mInstance;

    QMultiHash< QString, QgsSvgCacheEntry* > mEntryLookup;
    long mTotalSize;

    //The svg cache keeps the entries on a double connected list, moving the current entry to the front.
    //That way, removing entries for more space can start with the least used objects.
    QgsSvgCacheEntry* mLeastRecentEntry;
    QgsSvgCacheEntry* mMostRecentEntry;

    //Maximum cache size
    static const long mMaximumSize = 20000000;

    void replaceElemParams( QDomElement& elem, const QColor& fill, const QColor& outline, double outlineWidth );

    void containsElemParams( const QDomElement& elem, bool& hasFillParam, QColor& defaultFill, bool& hasOutlineParam, QColor& defaultOutline,
                             bool& hasOutlineWidthParam, double& defaultOutlineWidth ) const;

    void removeCacheEntry( QString s, QgsSvgCacheEntry* entry );

    void printEntryList();
};

#endif // QGSSVGCACHE_H