mapnik/src/placement_finder.cpp

/*****************************************************************************
 * 
 * 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
 *
 *****************************************************************************/

//$Id$

//mapnik
#include <mapnik/placement_finder.hpp>

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

// boost
#include <boost/shared_ptr.hpp>
#include <boost/utility.hpp>
#include <boost/ptr_container/ptr_vector.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/tuple/tuple.hpp>

//stl
#include <string>
#include <vector>

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

namespace mapnik
{
   template<>
   placement::placement(string_info *info_, 
                        CoordTransform *ctrans_, 
                        const proj_transform *proj_trans_, 
                        geometry2d const& geom_, 
                        shield_symbolizer const& sym)
      : info(info_), 
        ctrans(ctrans_), 
        proj_trans(proj_trans_), 
        geom(geom_),
        shape_path(*ctrans_, geom_, *proj_trans_), 
        total_distance_(-1.0), 
        displacement_(sym.get_displacement()),
        label_placement(sym.get_label_placement()), 
        wrap_width(sym.get_wrap_width()), 
        text_ratio(sym.get_text_ratio()), 
        label_spacing(sym.get_label_spacing()), 
        label_position_tolerance(sym.get_label_position_tolerance()), 
        force_odd_labels(sym.get_force_odd_labels()), 
        max_char_angle_delta(sym.get_max_char_angle_delta()),
        minimum_distance(sym.get_minimum_distance()),
        avoid_edges(sym.get_avoid_edges()),
        has_dimensions(true), 
        dimensions(std::make_pair(sym.get_image()->width(),
                             sym.get_image()->height()))
   {
   }
  
   template<>
   placement::placement(string_info *info_, 
                        CoordTransform *ctrans_, 
                        const proj_transform *proj_trans_, 
                        geometry2d const& geom_, 
                        text_symbolizer const& sym)
      : info(info_), 
        ctrans(ctrans_), 
        proj_trans(proj_trans_), 
        geom(geom_),
        shape_path(*ctrans_, geom_, *proj_trans_), 
        total_distance_(-1.0), 
        displacement_(sym.get_displacement()),
        label_placement(sym.get_label_placement()), 
        wrap_width(sym.get_wrap_width()), 
        text_ratio(sym.get_text_ratio()), 
        label_spacing(sym.get_label_spacing()), 
        label_position_tolerance(sym.get_label_position_tolerance()), 
        force_odd_labels(sym.get_force_odd_labels()), 
        max_char_angle_delta(sym.get_max_char_angle_delta()),
        minimum_distance(sym.get_minimum_distance()),
        avoid_edges(sym.get_avoid_edges()),
        has_dimensions(false), 
        dimensions()
   {
   }

  
   placement::~placement()
   {
   }
    
   unsigned placement::path_size() const
   {
      return geom.num_points();
   }
    
   std::pair<double, double> placement::get_position_at_distance(double target_distance)
   {
      double old_x, old_y, new_x, new_y;
      double x, y;
      x = y = 0.0;
        
      double distance = 0.0;
    
      shape_path.rewind(0);
      shape_path.vertex(&new_x,&new_y);
      unsigned num_points =  geom.num_points();
      for (unsigned i = 1; i < num_points; ++i)
      {
         double dx, dy;

         old_x = new_x;
         old_y = new_y;

         shape_path.vertex(&new_x,&new_y);
      
         dx = new_x - old_x;
         dy = new_y - old_y;
      
         double segment_length = sqrt(dx*dx + dy*dy);
      
         distance += segment_length;
         if (distance > target_distance)
         {
            x = new_x - dx*(distance - target_distance)/segment_length;
            y = new_y - dy*(distance - target_distance)/segment_length;

            break;
         }
      }
    
      return std::pair<double, double>(x, y);
   }
  
   double placement::get_total_distance()
   {
      if (total_distance_ < 0.0)
      {
         double old_x, old_y, new_x, new_y;
      
         shape_path.rewind(0);
     
         shape_path.vertex(&old_x,&old_y);

         total_distance_ = 0.0;
            
         unsigned num_points = geom.num_points();
         for (unsigned i = 1; i < num_points ; ++i)
         {
            double dx, dy;
            shape_path.vertex(&new_x,&new_y);
                
            dx = new_x - old_x;
            dy = new_y - old_y;
          
            total_distance_ += sqrt(dx*dx + dy*dy);
          
            old_x = new_x;
            old_y = new_y;
         }
      }
      
      return total_distance_;
   }
  
   void placement::clear_envelopes()
   {
      while (!envelopes.empty())
         envelopes.pop();
   }
  
  
   template <typename DetectorT>
   placement_finder<DetectorT>::placement_finder(DetectorT & detector,Envelope<double> const& e)
      : detector_(detector),
        dimensions_(e)
   {
   }

   template <typename DetectorT>
   std::vector<double> placement_finder<DetectorT>::get_ideal_placements(placement *p)
   {
      std::vector<double> ideal_label_distances;

      std::pair<double, double> string_dimensions = p->info->get_dimensions();
      double string_width = string_dimensions.first;

      double distance = p->get_total_distance();
    
      if (p->label_placement == LINE_PLACEMENT && string_width > distance)
      {
         //Empty!
         return ideal_label_distances;
      }
      
      int num_labels = 0;
      if (p->label_spacing && p->label_placement == LINE_PLACEMENT)
      {
         num_labels = static_cast<int> (floor(distance / (p->label_spacing + string_width)));
      }
      else if (p->label_spacing && p->label_placement == POINT_PLACEMENT)
      {
         num_labels = static_cast<int> (floor(distance / p->label_spacing));
      }
      
      if (p->force_odd_labels && num_labels%2 == 0)
         num_labels--;
      if (num_labels <= 0)
         num_labels = 1;


      double ideal_spacing = distance/num_labels;
      
      double middle; //try draw text centered
      if (p->label_placement == LINE_PLACEMENT)
        middle = (distance / 2.0) - (string_width/2.0);
      else //  (p->label_placement == point_placement)
        middle = distance / 2.0;
		
      if (num_labels % 2) //odd amount of labels
      {
         for (int a = 0; a < (num_labels+1)/2; a++)
         {
            ideal_label_distances.push_back(middle - (a*ideal_spacing));
	
            if (a != 0)
               ideal_label_distances.push_back(middle + (a*ideal_spacing));
         }
      }
      else //even amount of labels
      {
         for (int a = 0; a < num_labels/2; a++)
         {
            ideal_label_distances.push_back(middle - (ideal_spacing/2.0) - (a*ideal_spacing));
            ideal_label_distances.push_back(middle + (ideal_spacing/2.0) + (a*ideal_spacing));
         }
      }
      
      if (p->label_position_tolerance == 0)
      {
         p->label_position_tolerance = unsigned(ideal_spacing/2.0);
      }

      return ideal_label_distances;
   }

   template <typename DetectorT>
   void placement_finder<DetectorT>::find_placements(placement *p)
   {
      if (p->path_size() == 1) // point geometry
      {
         if ( build_path_horizontal(p, 0) ) 
         {
            update_detector(p);
         }
         return;
      }
      
      std::vector<double> ideal_label_distances = get_ideal_placements(p);
      
      double delta, tolerance, distance;
      distance = p->get_total_distance();
      tolerance = p->label_position_tolerance;
      delta = std::max ( 1.0, tolerance/100.0);

      std::vector<double>::const_iterator itr = ideal_label_distances.begin();
      std::vector<double>::const_iterator end = ideal_label_distances.end();
      for (; itr != end; ++itr)
      {
         bool placed = false;
         for (double i = 0; i < tolerance && !placed; i += delta)
         {
            for (int s = 1; s != -1; s-=2) {
               if (*itr + i*s > distance || *itr + i*s < 0.0) {
                 continue;
               }
               p->clear_envelopes();
               // check position +- delta for valid placement
               if ((p->label_placement == LINE_PLACEMENT &&
                    build_path_follow(p, *itr + (i*s)) ) ||
                   (p->label_placement == POINT_PLACEMENT &&
                    build_path_horizontal(p, *itr + (i*s))) )
               {
                  update_detector(p);
                  placed = true;
                  break;
               }
            }
         }
      }    
   }
   
   template <typename DetectorT>
   void placement_finder<DetectorT>::update_detector(placement *p)
   {
      while (!p->envelopes.empty())
      {
         Envelope<double> e = p->envelopes.front();

         detector_.insert(e, p->info->get_string());

         p->envelopes.pop();
      }
   }

   template <typename DetectorT>
   bool placement_finder<DetectorT>::build_path_follow(placement *p, double target_distance)
   {
      double new_x, new_y, old_x, old_y;
      unsigned cur_node = 0;
      double next_char_x = 0;
      double next_char_y = 0;

      double angle = 0.0;
      int orientation = 0;
      double displacement = boost::tuples::get<1>(p->displacement_); // displace by dy
      
      //p->current_placement.clear(); //TODO !!
      std::auto_ptr<placement_element> current_placement(new placement_element);
      
      double x, y;
      x = y = 0.0;
    
      double distance = 0.0;

      std::pair<double, double> string_dimensions = p->info->get_dimensions();
      //    double string_width = string_dimensions.first;
      double string_height = string_dimensions.second;
    
      // find the segment that our text should start on
      p->shape_path.rewind(0);
      p->shape_path.vertex(&new_x,&new_y);
      old_x = new_x;
      old_y = new_y;
      unsigned num_points = p->geom.num_points();
      for (unsigned i = 1; i < num_points; ++i)
      {
         double dx, dy;

         cur_node++;
        
         old_x = new_x;
         old_y = new_y;

         p->shape_path.vertex(&new_x,&new_y);
        
         dx = new_x - old_x;
         dy = new_y - old_y;
        
         double segment_length = sqrt(dx*dx + dy*dy);
        
         distance += segment_length;
         if (distance > target_distance)
         {
            // this segment is greater that the target starting distance so start here
            current_placement->starting_x = new_x - dx*(distance - target_distance)/segment_length;
            current_placement->starting_y = new_y - dy*(distance - target_distance)/segment_length;
    
            // angle text starts at and orientation
            angle = atan2(-dy, dx);
            orientation = (angle > 0.55*M_PI || angle < -0.45*M_PI) ? -1 : 1;

            distance -= target_distance;
            
            break;
         }
      }
        
      // now find the placement of each character starting from our initial segment
      // determined above
      double last_angle = angle; 
      for (unsigned i = 0; i < p->info->num_characters(); i++)
      {
         character_info ci;
         unsigned c;

         // grab the next character according to the orientation
         ci = orientation > 0 ? p->info->at(i) : p->info->at(p->info->num_characters() - i - 1);
         c = ci.character;
    
         double angle_delta = 0;

         // if the distance remaining in this segment is less than the character width
         // move to the next segment
         if (distance <= ci.width) 
         {
            last_angle = angle;
            while (distance <= ci.width) 
            {
               double dx, dy;
                    
               cur_node++;
                    
               if (cur_node >= p->geom.num_points()) {
                  return false;
               }
                    
               old_x = new_x;
               old_y = new_y;
                    
               p->shape_path.vertex(&new_x,&new_y);
                    
               dx = new_x - old_x;
               dy = new_y - old_y;
                    
               angle = atan2(-dy, dx );
               distance += sqrt(dx*dx+dy*dy);
            }
            // since our rendering angle has changed then check against our
            // max allowable angle change.
            angle_delta = last_angle - angle;
            // normalise between -180 and 180
            while (angle_delta > M_PI)
               angle_delta -= 2*M_PI;
            while (angle_delta < -M_PI)
               angle_delta += 2*M_PI;
            if (p->max_char_angle_delta > 0 && fabs(angle_delta) > p->max_char_angle_delta*(M_PI/180))
            {
               return false;
            }
         }
            
            
         Envelope<double> e;
         if (p->has_dimensions)
         {
            e.init(x, y, x + p->dimensions.first, y + p->dimensions.second);
         }


         double render_angle = angle;

         x = new_x - (distance)*cos(angle);
         y = new_y + (distance)*sin(angle);
         //Center the text on the line, unless displacement != 0
         if (displacement == 0.0) {
           x -= (((double)string_height/2.0) - 1.0)*cos(render_angle+M_PI/2);
           y += (((double)string_height/2.0) - 1.0)*sin(render_angle+M_PI/2);
         } else if (displacement*orientation > 0.0) {
           x -= ((fabs(displacement) - (double)string_height) + 1.0)*cos(render_angle+M_PI/2);
           y += ((fabs(displacement) - (double)string_height) + 1.0)*sin(render_angle+M_PI/2);
         } else { // displacement < 0
           x -= ((fabs(displacement) + (double)string_height) - 1.0)*cos(render_angle+M_PI/2);
           y += ((fabs(displacement) + (double)string_height) - 1.0)*sin(render_angle+M_PI/2);
         }
         distance -= ci.width;
         next_char_x = ci.width*cos(render_angle);
         next_char_y = ci.width*sin(render_angle);

         double render_x = x;
         double render_y = y;

         if (!p->has_dimensions)
         {
            // put four corners of the letter into envelope
            e.init(render_x, render_y, render_x + ci.width*cos(render_angle), render_y - ci.width*sin(render_angle));
            e.expand_to_include(render_x - ci.height*sin(render_angle), render_y - ci.height*cos(render_angle));
            e.expand_to_include(render_x + (ci.width*cos(render_angle) - ci.height*sin(render_angle)), render_y - (ci.width*sin(render_angle) + ci.height*cos(render_angle)));
         }

         if (!detector_.has_placement(e, p->info->get_string(), p->minimum_distance))
         {
            return false;
         }
            
         if (p->avoid_edges && !dimensions_.contains(e))
         {
            return false;
         }
        
         p->envelopes.push(e);

         if (orientation < 0)
         {
            // rotate in place
            render_x += ci.width*cos(render_angle) - (string_height-2)*sin(render_angle);
            render_y -= ci.width*sin(render_angle) + (string_height-2)*cos(render_angle);
            render_angle += M_PI;
         }
        
        
         current_placement->add_node(c,render_x - current_placement->starting_x, 
                                     -render_y + current_placement->starting_y, 
                                     render_angle);
         x += next_char_x;
         y -= next_char_y;
      }
      
      p->placements.push_back(current_placement.release());
      
      return true;
   }

   template <typename DetectorT>
   bool placement_finder<DetectorT>::build_path_horizontal(placement *p, double target_distance)
   {
      double x, y;

      //p->current_placement.clear(); // TODO
      std::auto_ptr<placement_element> current_placement(new placement_element);
      
      std::pair<double, double> string_dimensions = p->info->get_dimensions();
      double string_width = string_dimensions.first;
      double string_height = string_dimensions.second;
        
      // check if we need to wrap the string
      double wrap_at = string_width + 1;
      if (p->wrap_width && string_width > p->wrap_width)
      {
         if (p->text_ratio)
            for (int i = 1; ((wrap_at = string_width/i)/(string_height*i)) > p->text_ratio && (string_width/i) > p->wrap_width; ++i);
         else
            wrap_at = p->wrap_width;
      }
      
      // work out where our line breaks need to be
      std::vector<int> line_breaks;
      std::vector<double> line_widths;
      if (wrap_at < string_width && p->info->num_characters() > 0)
      {
         int line_count=0; 
         int last_space = 0;
         string_width = 0;
         string_height = 0;
         double line_width = 0;
         double line_height = 0;
         double word_width = 0;
         double word_height = 0;
         for (unsigned int ii = 0; ii < p->info->num_characters(); ii++)
         {
            character_info ci;
            ci = p->info->at(ii);
                
            unsigned c = ci.character;
            word_width += ci.width;
            word_height = word_height > ci.height ? word_height : ci.height;
            ++line_count;
        
            if (c == ' ')
            {
               last_space = ii;
               line_width += word_width;
               line_height = line_height > word_height ? line_height : word_height;
               word_width = 0;
               word_height = 0;
            }
            if (line_width > 0 && line_width > wrap_at)
            {
               string_width = string_width > line_width ? string_width : line_width;
               string_height += line_height;
               line_breaks.push_back(last_space);
               line_widths.push_back(line_width);
               ii = last_space;
               line_count = 0;
               line_width = 0;
               line_height = 0;
               word_width = 0;
               word_height = 0;
            }
         }
         line_width += word_width;
         string_width = string_width > line_width ? string_width : line_width;
         line_breaks.push_back(p->info->num_characters() + 1);
         line_widths.push_back(line_width);
      }
      if (line_breaks.size() == 0)
      {
         line_breaks.push_back(p->info->num_characters() + 1);
         line_widths.push_back(string_width);
      }
        
      p->info->set_dimensions(string_width, string_height);
        
      if (p->geom.type() == LineString)
      {
         std::pair<double, double> starting_pos = p->get_position_at_distance(target_distance);
            
         current_placement->starting_x = starting_pos.first;
         current_placement->starting_y = starting_pos.second;
      }
      else
      {
         p->geom.label_position(&current_placement->starting_x, &current_placement->starting_y);
         //  TODO: 
         //  We would only want label position in final 'paper' coords.
         //  Move view and proj transforms to e.g. label_position(x,y,proj_trans,ctrans)?
         double z=0;  
         p->proj_trans->backward(current_placement->starting_x,current_placement->starting_y, z);
         p->ctrans->forward(&current_placement->starting_x, &current_placement->starting_y);
         // apply displacement ( in pixels ) 
         current_placement->starting_x += boost::tuples::get<0>(p->displacement_);
         current_placement->starting_y += boost::tuples::get<1>(p->displacement_); 
      }
        
      double line_height = 0;
      unsigned int line_number = 0;
      unsigned int index_to_wrap_at = line_breaks[line_number];
      double line_width = line_widths[line_number];
    
      x = -line_width/2.0 - 1.0;
      y = -string_height/2.0 + 1.0;
    
      for (unsigned i = 0; i < p->info->num_characters(); i++)
      {
         character_info ci;;
         ci = p->info->at(i);
            
         unsigned c = ci.character;
         if (i == index_to_wrap_at)
         {
            index_to_wrap_at = line_breaks[++line_number];
            line_width = line_widths[line_number];
            y -= line_height;
            x = -line_width/2.0;
            line_height = 0;
            continue;
         }
         else
         {
            current_placement->add_node(c, x, y, 0.0);
    
            Envelope<double> e;
            if (p->has_dimensions)
            {
               e.init(current_placement->starting_x - (p->dimensions.first/2.0), 
                      current_placement->starting_y - (p->dimensions.second/2.0), 
                      current_placement->starting_x + (p->dimensions.first/2.0), 
                      current_placement->starting_y + (p->dimensions.second/2.0));
            }
            else
            {
               e.init(current_placement->starting_x + x, 
                      current_placement->starting_y - y, 
                      current_placement->starting_x + x + ci.width, 
                      current_placement->starting_y - y - ci.height);
            }
                
            if (!detector_.has_placement(e, p->info->get_string(), p->minimum_distance))
            {
               return false;
            }

            if (p->avoid_edges && !dimensions_.contains(e))
            {
               return false;
            }
                
            p->envelopes.push(e);
         }
         x += ci.width;
         line_height = line_height > ci.height ? line_height : ci.height;
      }
      p->placements.push_back(current_placement.release());
      
      return true;
   }
   
   template <typename DetectorT>
   void placement_finder<DetectorT>::clear()
   {
      detector_.clear();
   }
   
   template class placement_finder<label_collision_detector4>;
   
} // namespace