402 lines
10 KiB
C++
402 lines
10 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2011 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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#ifndef MAPNIK_GEOMETRY_HPP
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#define MAPNIK_GEOMETRY_HPP
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// mapnik
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#include <mapnik/vertex_vector.hpp>
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#include <mapnik/geom_util.hpp>
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// boost
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#include <boost/shared_ptr.hpp>
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#include <boost/utility.hpp>
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#include <boost/ptr_container/ptr_vector.hpp>
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namespace mapnik {
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enum eGeomType {
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Unknown = 0,
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Point = 1,
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LineString = 2,
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Polygon = 3
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};
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template <typename T, template <typename> class Container=vertex_vector>
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class geometry : private::boost::noncopyable
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{
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public:
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typedef T coord_type;
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typedef Container<coord_type> container_type;
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typedef typename container_type::value_type value_type;
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typedef typename container_type::size_type size_type;
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private:
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container_type cont_;
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eGeomType type_;
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mutable unsigned itr_;
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public:
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geometry()
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: type_(Unknown),
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itr_(0)
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{}
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explicit geometry(eGeomType type)
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: type_(type),
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itr_(0)
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{}
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eGeomType type() const
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{
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return type_;
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}
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void set_type(eGeomType type)
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{
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type_ = type;
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}
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container_type const& data() const
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{
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return cont_;
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}
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box2d<double> envelope() const
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{
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box2d<double> result;
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double x(0);
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double y(0);
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rewind(0);
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for (unsigned i=0;i<num_points();++i)
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{
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vertex(&x,&y);
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if (i==0)
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{
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result.init(x,y,x,y);
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}
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else
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{
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result.expand_to_include(x,y);
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}
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}
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return result;
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}
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void label_interior_position(double *x, double *y) const
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{
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// start with the default label position
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label_position(x,y);
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unsigned size = cont_.size();
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// if we are not a polygon, or the default is within the polygon we are done
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if (size < 3 || hit_test(*x,*y,0))
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return;
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// otherwise we find a horizontal line across the polygon and then return the
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// center of the widest intersection between the polygon and the line.
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std::vector<double> intersections; // only need to store the X as we know the y
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double x0=0;
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double y0=0;
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rewind(0);
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unsigned command = vertex(&x0, &y0);
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double x1,y1;
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while (SEG_END != (command=vertex(&x1, &y1)))
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{
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if (command != SEG_MOVETO)
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{
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// if the segments overlap
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if (y0==y1)
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{
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if (y0==*y)
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{
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double xi = (x0+x1)/2.0;
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intersections.push_back(xi);
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}
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}
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// if the path segment crosses the bisector
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else if ((y0 <= *y && y1 >= *y) ||
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(y0 >= *y && y1 <= *y))
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{
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// then calculate the intersection
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double xi = x0;
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if (x0 != x1)
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{
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double m = (y1-y0)/(x1-x0);
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double c = y0 - m*x0;
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xi = (*y-c)/m;
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}
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intersections.push_back(xi);
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}
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}
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x0 = x1;
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y0 = y1;
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}
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// no intersections we just return the default
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if (intersections.empty())
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return;
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x0=intersections[0];
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double max_width = 0;
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for (unsigned ii = 1; ii < intersections.size(); ++ii)
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{
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double x1=intersections[ii];
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double xc=(x0+x1)/2.0;
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double width = fabs(x1-x0);
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if (width > max_width && hit_test(xc,*y,0))
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{
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*x=xc;
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max_width = width;
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}
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}
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}
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/* center of gravity centroid
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- best visually but does not work with multipolygons
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*/
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void label_position(double *x, double *y) const
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{
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if (type_ == LineString)
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{
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middle_point(x,y);
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return;
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}
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unsigned size = cont_.size();
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if (size < 3)
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{
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cont_.get_vertex(0,x,y);
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return;
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}
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double ai;
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double atmp = 0;
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double xtmp = 0;
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double ytmp = 0;
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double x0 =0;
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double y0 =0;
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double x1 =0;
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double y1 =0;
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double ox =0;
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double oy =0;
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unsigned i;
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// Use first point as origin to improve numerical accuracy
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cont_.get_vertex(0,&ox,&oy);
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for (i = 0; i < size-1; i++)
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{
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cont_.get_vertex(i,&x0,&y0);
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cont_.get_vertex(i+1,&x1,&y1);
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x0 -= ox; y0 -= oy;
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x1 -= ox; y1 -= oy;
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ai = x0 * y1 - x1 * y0;
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atmp += ai;
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xtmp += (x1 + x0) * ai;
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ytmp += (y1 + y0) * ai;
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}
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if (atmp != 0)
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{
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*x = (xtmp/(3*atmp)) + ox;
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*y = (ytmp/(3*atmp)) + oy;
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return;
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}
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*x=x0;
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*y=y0;
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}
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/* center of bounding box centroid */
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void label_position2(double *x, double *y) const
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{
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box2d<double> box = envelope();
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*x = box.center().x;
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*y = box.center().y;
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}
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/* summarized distance centroid */
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void label_position3(double *x, double *y) const
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{
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if (type_ == LineString)
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{
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middle_point(x,y);
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return;
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}
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unsigned i = 0;
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double l = 0.0;
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double tl = 0.0;
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double cx = 0.0;
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double cy = 0.0;
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double x0 = 0.0;
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double y0 = 0.0;
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double x1 = 0.0;
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double y1 = 0.0;
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unsigned size = cont_.size();
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for (i = 0; i < size-1; i++)
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{
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cont_.get_vertex(i,&x0,&y0);
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cont_.get_vertex(i+1,&x1,&y1);
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l = distance(x0,y0,x1,y1);
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cx += l * (x1 + x0)/2;
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cy += l * (y1 + y0)/2;
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tl += l;
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}
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*x = cx / tl;
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*y = cy / tl;
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}
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void middle_point(double *x, double *y) const
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{
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// calculate mid point on path
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double x0=0;
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double y0=0;
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double x1=0;
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double y1=0;
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unsigned size = cont_.size();
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if (size == 1)
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{
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cont_.get_vertex(0,x,y);
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}
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else if (size == 2)
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{
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cont_.get_vertex(0,&x0,&y0);
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cont_.get_vertex(1,&x1,&y1);
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*x = 0.5 * (x1 + x0);
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*y = 0.5 * (y1 + y0);
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}
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else
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{
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double len=0.0;
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for (unsigned pos = 1; pos < size; ++pos)
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{
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cont_.get_vertex(pos-1,&x0,&y0);
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cont_.get_vertex(pos,&x1,&y1);
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double dx = x1 - x0;
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double dy = y1 - y0;
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len += std::sqrt(dx * dx + dy * dy);
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}
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double midlen = 0.5 * len;
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double dist = 0.0;
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for (unsigned pos = 1; pos < size;++pos)
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{
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cont_.get_vertex(pos-1,&x0,&y0);
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cont_.get_vertex(pos,&x1,&y1);
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double dx = x1 - x0;
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double dy = y1 - y0;
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double seg_len = std::sqrt(dx * dx + dy * dy);
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if (( dist + seg_len) >= midlen)
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{
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double r = (midlen - dist)/seg_len;
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*x = x0 + (x1 - x0) * r;
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*y = y0 + (y1 - y0) * r;
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break;
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}
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dist += seg_len;
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}
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}
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}
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void push_vertex(coord_type x, coord_type y, CommandType c)
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{
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cont_.push_back(x,y,c);
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}
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void line_to(coord_type x,coord_type y)
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{
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push_vertex(x,y,SEG_LINETO);
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}
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void move_to(coord_type x,coord_type y)
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{
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push_vertex(x,y,SEG_MOVETO);
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}
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unsigned num_points() const
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{
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return cont_.size();
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}
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unsigned vertex(double* x, double* y) const
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{
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return cont_.get_vertex(itr_++,x,y);
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}
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unsigned get_vertex(unsigned pos, double* x, double* y) const
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{
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return cont_.get_vertex(pos, x, y);
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}
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void rewind(unsigned ) const
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{
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itr_=0;
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}
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bool hit_test(coord_type x, coord_type y, double tol) const
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{
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if (cont_.size() == 1) {
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// Handle points
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double x0, y0;
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cont_.get_vertex(0, &x0, &y0);
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return distance(x, y, x0, y0) <= fabs(tol);
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} else if (cont_.size() > 1) {
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bool inside=false;
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double x0=0;
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double y0=0;
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rewind(0);
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vertex(&x0, &y0);
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unsigned command;
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double x1,y1;
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while (SEG_END != (command=vertex(&x1, &y1)))
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{
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if (command == SEG_MOVETO)
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{
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x0 = x1;
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y0 = y1;
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continue;
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}
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if ((((y1 <= y) && (y < y0)) ||
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((y0 <= y) && (y < y1))) &&
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( x < (x0 - x1) * (y - y1)/ (y0 - y1) + x1))
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inside=!inside;
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x0=x1;
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y0=y1;
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}
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return inside;
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}
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return false;
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}
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};
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typedef geometry<double,vertex_vector> geometry_type;
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typedef boost::shared_ptr<geometry_type> geometry_ptr;
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typedef boost::ptr_vector<geometry_type> geometry_container;
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}
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#endif // MAPNIK_GEOMETRY_HPP
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