115 lines
4.4 KiB
C++
115 lines
4.4 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) 2012 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 PLACEMENTS_BASE_HPP
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#define PLACEMENTS_BASE_HPP
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// mapnik
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#include <mapnik/config.hpp>
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#include <mapnik/text_properties.hpp>
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#include <mapnik/formatting/base.hpp>
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namespace mapnik
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{
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typedef std::pair<double,double> dimension_type;
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class MAPNIK_DECL text_placements;
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/** Generate a possible placement and store results of placement_finder.
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* This placement has first to be tested by placement_finder to verify it
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* can actually be used.
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*/
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class MAPNIK_DECL text_placement_info : mapnik::noncopyable
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{
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public:
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/** Constructor. Takes the parent text_placements object as a parameter
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* to read defaults from it. */
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text_placement_info(text_placements const* parent, double scale_factor_);
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/** Get next placement.
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* This function is also called before the first placement is tried.
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* Each class has to return at least one position!
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* If this functions returns false the placement data should be
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* considered invalid!
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*/
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virtual bool next()=0;
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virtual ~text_placement_info() {}
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/** Properties actually used by placement finder and renderer. Values in
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* here are modified each time next() is called. */
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text_symbolizer_properties properties;
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/** Scale factor used by the renderer. */
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double scale_factor;
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/** Set scale factor. */
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void set_scale_factor(double factor) { scale_factor = factor; }
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/** Get scale factor. */
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double get_scale_factor() const { return scale_factor; }
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/** Get label spacing taking the scale factor into account. */
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double get_actual_label_spacing() const { return scale_factor * properties.label_spacing; }
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/** Get minimum distance taking the scale factor into account. */
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double get_actual_minimum_distance() const { return scale_factor * properties.minimum_distance; }
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/** Get minimum padding taking the scale factor into account. */
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double get_actual_minimum_padding() const { return scale_factor * properties.minimum_padding; }
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};
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typedef boost::shared_ptr<text_placement_info> text_placement_info_ptr;
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/** This object handles the management of all TextSymbolizer properties. It can
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* be used as a base class for own objects which implement new processing
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* semantics. Basically this class just makes sure a pointer of the right
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* class is returned by the get_placement_info call.
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*/
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class MAPNIK_DECL text_placements
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{
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public:
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text_placements();
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/** Get a text_placement_info object to use in rendering.
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* The returned object creates a list of settings which is
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* used to try to find a placement and stores all
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* information that is generated by
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* the placement finder.
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*
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* This function usually is implemented as
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* text_placement_info_ptr text_placements_XXX::get_placement_info() const
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* {
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* return text_placement_info_ptr(new text_placement_info_XXX(this));
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* }
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*/
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virtual text_placement_info_ptr get_placement_info(
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double scale_factor_) const =0;
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/** Get a list of all expressions used in any placement.
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* This function is used to collect attributes.
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*/
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virtual void add_expressions(expression_set &output);
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/** Destructor. */
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virtual ~text_placements() {}
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/** List of all properties used as the default for the subclasses. */
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text_symbolizer_properties defaults;
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};
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/** Pointer to object of class text_placements */
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typedef boost::shared_ptr<text_placements> text_placements_ptr;
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} //ns mapnik
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#endif // PLACEMENTS_BASE_HPP
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