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git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@2136 c8812cc2-4d05-0410-92ff-de0c093fc19c
90 lines
3.4 KiB
C++
90 lines
3.4 KiB
C++
/***************************************************************************
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qgssvgcache.h - SVG rendering and pixmap caching
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-------------------
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begin : Sat Jul 17 2004
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copyright : (C) 2004 by Lars Luthman
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email : larsl at users dot sourceforge dot org
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***************************************************************************/
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/***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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/* $Id$ */
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#ifndef QGSSVGCACHE_H
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#define QGSSVGCACHE_H
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#include <map>
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#include <queue>
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#include <qpixmap.h>
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/** This class is a singleton that does all the SVG rendering in QGIS.
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When another part of the program needs to render an SVG file, it
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calls the getPixmap() function to get a pixmap rendering of that
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SVG file in the wanted scale. This class also does some extra
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tricks to make Qt's SVG renderings look a little bit better, and
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it caches the pixmaps to speed things up.
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*/
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class QgsSVGCache {
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public:
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QgsSVGCache();
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/** This function returns a pixmap containing a rendering of the SVG file
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@c filename scaled by the factor @c scaleFactor. The pixmaps background
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will be transparent, and if the file for some reason can't be rendered
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the pixmap will be completely transparent. */
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QPixmap getPixmap(QString filename, double scaleFactor);
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/** This function clears the pixmap cache and forces all newly requested
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pixmaps to be rendered again. Can be useful if the oversampling factor
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has changed and you want to get rid of cached lower-quality pixmaps. */
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void clear();
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/** When a pixmap is requested and it is not in the cache, it will be
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loaded using a QPicture and rendered to a QPixmap. Since Qt does not do
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any kind of anti-aliasing or smoothing, the QPicture is first rendered
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to a pixmap that is larger than the requested size, and then it's scaled
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down using QImage::smoothScale() to smooth out sharp edges and lines.
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The oversampling factor determins how much larger the first pixmap is -
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the larger this factor is the smoother the final pixmap will look, but
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it will also take longer time to render and scale the image. This
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function sets the oversampling factor. It should be larger than or equal
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to 1.
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*/
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void setOversampling(int oversamplingFactor);
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/** This function returns the oversampling factor.
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@see setOversampling()
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*/
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int getOversampling() const;
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/** This function returns a reference to the singleton object. */
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static inline QgsSVGCache& instance();
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protected:
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typedef std::map<std::pair<QString, double>, QPixmap> PixmapMap;
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PixmapMap pixmapMap;
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int oversampling;
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std::queue<PixmapMap::key_type> fifo;
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int pixelLimit;
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int totalPixels;
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};
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QgsSVGCache& QgsSVGCache::instance() {
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static QgsSVGCache obj;
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return obj;
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}
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#endif
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