/home/andreas/src/svn/mapnik/include/mapnik/ctrans.hpp

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/*****************************************************************************
 * 
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 Artem Pavlenko
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

//$Id: ctrans.hpp 39 2005-04-10 20:39:53Z pavlenko $

#ifndef CTRANS_HPP
#define CTRANS_HPP

#include <mapnik/envelope.hpp>
#include <mapnik/coord_array.hpp>
#include <mapnik/proj_transform.hpp>

namespace mapnik {
    typedef coord_array<coord2d> CoordinateArray;
    
    template <typename Transform,typename Geometry>
    struct MAPNIK_DECL coord_transform
    {
        coord_transform(Transform const& t, Geometry& geom)
            : t_(t), geom_(geom) {}
        
        unsigned  vertex(double *x , double *y) const
        {
            unsigned command = geom_.vertex(x,y);
            t_.forward(x,y);
            return command;
        }
        
        void rewind (unsigned pos)
        {
            geom_.rewind(pos);
        }
        
    private:
        Transform const& t_;
        Geometry& geom_;
    };

    template <typename Transform,typename Geometry>
    struct MAPNIK_DECL coord_transform2
    {
        coord_transform2(Transform const& t, 
                         Geometry& geom, 
                         proj_transform const& prj_trans)
            : t_(t), 
              geom_(geom), 
              prj_trans_(prj_trans)  {}
        
        unsigned  vertex(double * x , double  * y) const
        {
            unsigned command = geom_.vertex(x,y);
            double z=0;
            prj_trans_.backward(*x,*y,z);
            t_.forward(x,y);
            return command;
        }
        
        void rewind (unsigned pos)
        {
            geom_.rewind(pos);
        }
        
    private:
        Transform const& t_;
        Geometry& geom_;
        proj_transform const& prj_trans_;
    };
    

    class CoordTransform
    {
    private:
            int width;
            int height;
            double scale_;
            Envelope<double> extent_;
        double offset_x_,offset_y_;
    public:
        CoordTransform(int width,int height,const Envelope<double>& extent,
                       double offset_x = 0, double offset_y = 0)
            :width(width),height(height),extent_(extent),offset_x_(offset_x),offset_y_(offset_y)
        {
            double sx=((double)width)/extent_.width();
            double sy=((double)height)/extent_.height();
            scale_=std::min(sx,sy);
        }
        
        inline double scale() const
        {
            return scale_;
        }
        
        inline void forward(double * x, double * y) const
        {
            
            *x = (*x - extent_.minx()) * scale_ - offset_x_;
            *y = (extent_.maxy() - *y) * scale_ - offset_y_;
        }
        
        inline void backward(double * x, double * y) const
        {
            *x = extent_.minx() + (*x + offset_x_)/scale_;
            *y = extent_.maxy() - (*y + offset_y_)/scale_;
        }
        
        inline coord2d& forward(coord2d& c) const
        {
            forward(&c.x,&c.y);
            return c;
        }

        inline coord2d& backward(coord2d& c) const
        {
            backward(&c.x,&c.y);
            return c;
        }

        inline Envelope<double> forward(const Envelope<double>& e) const
        {
            double x0 = e.minx();
            double y0 = e.miny();
            double x1 = e.maxx();
            double y1 = e.maxy();
            forward(&x0,&y0);
            forward(&x1,&y1);
            return Envelope<double>(x0,y0,x1,y1);
        }

        inline Envelope<double> backward(const Envelope<double>& e) const
        {
            double x0 = e.minx();
            double y0 = e.miny();
            double x1 = e.maxx();
            double y1 = e.maxy();
            backward(&x0,&y0);
            backward(&x1,&y1);
            return Envelope<double>(x0,y0,x1,y1);
        }

        inline CoordinateArray& forward(CoordinateArray& coords) const
        {
            for (unsigned i=0;i<coords.size();++i)
            {
                forward(coords[i]);
            }
            return coords;
        }
        
        inline CoordinateArray& backward(CoordinateArray& coords) const
        {
            for (unsigned i=0;i<coords.size();++i)
            {
                backward(coords[i]);
            }
            return coords;
        }
    };
}

#endif //CTRANS_HPP

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