101 lines
3.1 KiB
C++
101 lines
3.1 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) 2016 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 MAPNIK_TOLERANCE_ITERATOR_HPP
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#define MAPNIK_TOLERANCE_ITERATOR_HPP
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//mapnik
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#include <mapnik/debug.hpp>
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namespace mapnik
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{
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class tolerance_iterator
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{
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public:
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tolerance_iterator(double label_position_tolerance, double spacing)
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: tolerance_(label_position_tolerance > 0 ?
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label_position_tolerance : spacing/2.0),
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linear_position_(1.0),
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value_(0),
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initialized_(false),
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values_tried_(0)
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{
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}
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~tolerance_iterator()
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{
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//std::cout << "values tried:" << values_tried_ << "\n";
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}
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double get() const
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{
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return -value_;
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}
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bool next()
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{
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++values_tried_;
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if (values_tried_ > 255)
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{
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/* This point should not be reached during normal operation. But I can think of
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* cases where very bad spacing and or tolerance values are choosen and the
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* placement finder tries an excessive number of placements.
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* 255 is an arbitrarily chosen limit.
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*/
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MAPNIK_LOG_WARN(placement_finder) << "Tried a huge number of placements. Please check "
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"'label-position-tolerance' and 'spacing' parameters "
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"of your TextSymbolizers.\n";
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return false;
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}
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if (!initialized_)
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{
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initialized_ = true;
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return true; //Always return value 0 as the first value.
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}
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if (value_ == 0)
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{
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value_ = linear_position_;
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return true;
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}
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value_ = -value_;
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if (value_ > 0)
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{
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value_ = std::pow(1.3, linear_position_) * linear_position_ / (4.0 * tolerance_) + linear_position_;
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linear_position_ += 1.0;
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}
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if (value_ > tolerance_)
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{
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return false;
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}
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return true;
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}
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private:
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double tolerance_;
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double linear_position_;
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double value_;
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bool initialized_;
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unsigned values_tried_;
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};
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}//ns mapnik
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#endif // MAPNIK_TOLERANCE_ITERATOR_HPP
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