mapnik/src/agg/process_text_symbolizer.cpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2011 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
 *
 *****************************************************************************/
//$Id$

// mapnik
#include <mapnik/agg_renderer.hpp>
#include <mapnik/agg_rasterizer.hpp>
#include <mapnik/expression_evaluator.hpp>

namespace mapnik {

template <typename T>
void agg_renderer<T>::process(text_symbolizer const& sym,
                              Feature const& feature,
                              proj_transform const& prj_trans)
{


    // Use a boost::ptr_vector here instread of std::vector?
    std::vector<geometry_type*> geometries_to_process;
    unsigned num_geom = feature.num_geometries();
    for (unsigned i=0; i<num_geom; ++i)
    {
        geometry_type const& geom = feature.get_geometry(i);
        
        if (geom.num_points() == 0) continue; // don't bother with empty geometries
        
        if ((geom.type() == Polygon) && sym.get_minimum_path_length() > 0)
        {
            // TODO - find less costly method than fetching full envelope
            box2d<double> gbox = t_.forward(geom.envelope(),prj_trans);
            if (gbox.width() < sym.get_minimum_path_length())
            {
                continue;
            }
        }
        // TODO - calculate length here as well
        geometries_to_process.push_back(const_cast<geometry_type*>(&geom));
    }
    
    if (!geometries_to_process.size() > 0)
        return; // early return to avoid significant overhead of rendering setup

    typedef  coord_transform2<CoordTransform,geometry_type> path_type;

    bool placement_found = false;
    text_placement_info_ptr placement_options = sym.get_placement_options()->get_placement_info();
    while (!placement_found && placement_options->next())
    {
        expression_ptr name_expr = sym.get_name();
        if (!name_expr) return;
        value_type result = boost::apply_visitor(evaluate<Feature,value_type>(feature),*name_expr);
        UnicodeString text = result.to_unicode();

        if ( sym.get_text_transform() == UPPERCASE)
        {
            text = text.toUpper();
        }
        else if ( sym.get_text_transform() == LOWERCASE)
        {
            text = text.toLower();
        }
        else if ( sym.get_text_transform() == CAPITALIZE)
        {
            text = text.toTitle(NULL);
        }

        if ( text.length() <= 0 ) continue;
        color const& fill = sym.get_fill();

        face_set_ptr faces;

        if (sym.get_fontset().size() > 0)
        {
            faces = font_manager_.get_face_set(sym.get_fontset());
        }
        else
        {
            faces = font_manager_.get_face_set(sym.get_face_name());
        }

        stroker_ptr strk = font_manager_.get_stroker();
        if (!(faces->size() > 0 && strk))
        {
            throw config_error("Unable to find specified font face '" + sym.get_face_name() + "'");
        }
        text_renderer<T> ren(pixmap_, faces, *strk);
        
        ren.set_character_size(placement_options->text_size * scale_factor_);
        ren.set_fill(fill);
        ren.set_halo_fill(sym.get_halo_fill());
        ren.set_halo_radius(sym.get_halo_radius() * scale_factor_);
        ren.set_opacity(sym.get_text_opacity());
        
        box2d<double> dims(0,0,width_,height_);
        placement_finder<label_collision_detector4> finder(*detector_,dims);

        string_info info(text);

        faces->get_string_info(info);
        metawriter_with_properties writer = sym.get_metawriter();

        BOOST_FOREACH( geometry_type * geom, geometries_to_process )
        {
            while (!placement_found && placement_options->next_position_only())
            {
                placement text_placement(info, sym, scale_factor_);
                text_placement.avoid_edges = sym.get_avoid_edges();
                if (writer.first)
                    text_placement.collect_extents =true; // needed for inmem metawriter

                if (sym.get_label_placement() == POINT_PLACEMENT ||
                        sym.get_label_placement() == INTERIOR_PLACEMENT)
                {
                    double label_x=0.0;
                    double label_y=0.0;
                    double z=0.0;
                    if (sym.get_label_placement() == POINT_PLACEMENT)
                        geom->label_position(&label_x, &label_y);
                    else
                        geom->label_interior_position(&label_x, &label_y);
                    prj_trans.backward(label_x,label_y, z);
                    t_.forward(&label_x,&label_y);

                    double angle = 0.0;
                    expression_ptr angle_expr = sym.get_orientation();
                    if (angle_expr)
                    {
                        // apply rotation
                        value_type result = boost::apply_visitor(evaluate<Feature,value_type>(feature),*angle_expr);
                        angle = result.to_double();
                    }

                    finder.find_point_placement(text_placement, placement_options, label_x,label_y,
                                                angle, sym.get_line_spacing(),
                                                sym.get_character_spacing());
                    finder.update_detector(text_placement);
                }
                else if ( geom->num_points() > 1 && sym.get_label_placement() == LINE_PLACEMENT)
                {
                    path_type path(t_,*geom,prj_trans);
                    finder.find_line_placements<path_type>(text_placement, placement_options, path);
                }

                if (!text_placement.placements.size()) continue;
                placement_found = true;

                for (unsigned int ii = 0; ii < text_placement.placements.size(); ++ii)
                {
                    double x = text_placement.placements[ii].starting_x;
                    double y = text_placement.placements[ii].starting_y;
                    ren.prepare_glyphs(&text_placement.placements[ii]);
                    ren.render(x,y);
                }

                if (writer.first) writer.first->add_text(text_placement, faces, feature, t_, writer.second);
            }
        }
    }
}

template void agg_renderer<image_32>::process(text_symbolizer const&,
                                              Feature const&,
                                              proj_transform const&);

}