mapnik/include/mapnik/placement_finder.hpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 Artem Pavlenko
 * Copyright (C) 2006 10East Corp.
 *
 * 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
 *
 *****************************************************************************/

//$Id$

#ifndef __PLACEMENT_FINDER__
#define __PLACEMENT_FINDER__

#include <mapnik/ctrans.hpp>
#include <mapnik/label_collision_detector.hpp>
#include <mapnik/text_symbolizer.hpp>
#include <mapnik/shield_symbolizer.hpp>
#include <mapnik/geometry.hpp>
#include <mapnik/text_path.hpp>

#include <queue>

namespace mapnik
{
typedef text_path placement_element;

struct placement : boost::noncopyable
{
    placement(string_info & info_, shield_symbolizer const& sym, unsigned w, unsigned h, bool has_dimensions_= false);

    placement(string_info & info_, text_symbolizer const& sym);

    ~placement();

    string_info & info; // should only be used for finding placement. doesn't necessarily match placements.vertex() values

    position displacement_;
    label_placement_e label_placement;

    std::queue< box2d<double> > envelopes;

    //output
    boost::ptr_vector<placement_element> placements;

    int wrap_width;
    bool wrap_before; // wraps text at wrap_char immediately before current word
    unsigned char wrap_char;
    int text_ratio;

    int label_spacing; // distance between repeated labels on a single geometry
    unsigned label_position_tolerance; //distance the label can be moved on the line to fit, if 0 the default is used
    bool force_odd_labels; //Always try render an odd amount of labels

    double max_char_angle_delta;
    double minimum_distance;
    bool avoid_edges;
    bool has_dimensions;
    bool allow_overlap;
    std::pair<double, double> dimensions;
    int text_size;
};



template <typename DetectorT>
class placement_finder : boost::noncopyable
{
public:
    placement_finder(DetectorT & detector);

    //Try place a single label at the given point
    void find_point_placement(placement & p, double pos_x, double pos_y, double angle=0.0, vertical_alignment_e = MIDDLE, unsigned line_spacing=0, unsigned character_spacing=0, horizontal_alignment_e = H_MIDDLE, justify_alignment_e = J_MIDDLE);

    //Iterate over the given path, placing point labels with respect to label_spacing
    template <typename T>
    void find_point_placements(placement & p, T & path);

    //Iterate over the given path, placing line-following labels with respect to label_spacing
    template <typename T>
    void find_line_placements(placement & p, T & path);

    void update_detector(placement & p);

    void clear();

private:
    ///Helpers for find_line_placement

    ///Returns a possible placement on the given line, does not test for collisions
    //index: index of the node the current line ends on
    //distance: distance along the given index that the placement should start at, this includes the offset,
    //          as such it may be > or < the length of the current line, so this must be checked for
    //orientation: if set to != 0 the placement will be attempted with the given orientation
    //             otherwise it will autodetect the orientation.
    //             If >= 50% of the characters end up upside down, it will be retried the other way.
    //             RETURN: 1/-1 depending which way up the string ends up being.
    std::auto_ptr<placement_element> get_placement_offset(placement & p,
                                                          const std::vector<vertex2d> & path_positions,
                                                          const std::vector<double> & path_distances,
                                                          int & orientation, unsigned index, double distance);

    ///Tests wether the given placement_element be placed without a collision
    // Returns true if it can
    // NOTE: This edits p.envelopes so it can be used afterwards (you must clear it otherwise)
    bool test_placement(placement & p, const std::auto_ptr<placement_element> & current_placement, const int & orientation);

    ///Does a line-circle intersect calculation
    // NOTE: Follow the strict pre conditions
    // Pre Conditions: x1,y1 is within radius distance of cx,cy. x2,y2 is outside radius distance of cx,cy
    //                 This means there is exactly one intersect point
    // Result is returned in ix, iy
    void find_line_circle_intersection(
        const double &cx, const double &cy, const double &radius,
        const double &x1, const double &y1, const double &x2, const double &y2,
        double &ix, double &iy);

    ///General Internals



    DetectorT & detector_;
    box2d<double> const& dimensions_;
};
}

#endif