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106 lines
3.7 KiB
C++
106 lines
3.7 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) 2025 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/text_properties.hpp>
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#include <mapnik/text/formatting/base.hpp>
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namespace mapnik {
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using dimension_type = std::pair<double, double>;
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class MAPNIK_DECL text_placements;
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class feature_impl;
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struct attribute;
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// Generate a possible placement.
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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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class MAPNIK_DECL text_placement_info : util::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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virtual bool next() const = 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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mutable 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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};
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using text_placement_info_ptr = std::shared_ptr<text_placement_info>;
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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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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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// 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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virtual text_placement_info_ptr
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get_placement_info(double _scale_factor, feature_impl const& feature, attributes const& vars) 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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virtual void add_expressions(expression_set& output) const;
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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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using text_placements_ptr = std::shared_ptr<text_placements>;
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} // namespace mapnik
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#endif // PLACEMENTS_BASE_HPP
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