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mapnik/plugins/input/tiles/mvt_io.hpp

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4.1 KiB
C++

// SPDX-License-Identifier: LGPL-2.1-or-later
/*****************************************************************************
*
* This file is part of Mapnik Vector Tile Plugin
*
* Copyright (C) 2023 Geofabrik GmbH
* Copyright (C) 2025 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
*
*****************************************************************************/
#ifndef PLUGINS_INPUT_MBTILES_VECTOR_MVT_IO_HPP_
#define PLUGINS_INPUT_MBTILES_VECTOR_MVT_IO_HPP_
#include <memory>
#include <type_traits>
#include <protozero/pbf_message.hpp>
#include <mapnik/feature.hpp>
#include <mapnik/unicode.hpp>
#include "mvt_message.hpp"
using pbf_attr_value_type = mapnik::util::variant<std::string, float, double, int64_t, uint64_t, bool>;
class mvt_io
{
struct value_visitor
{
mapnik::transcoder& tr_;
mapnik::feature_ptr& feature_;
std::string const& name_;
value_visitor(mapnik::transcoder& tr, mapnik::feature_ptr& feature, std::string const& name)
: tr_(tr)
, feature_(feature)
, name_(name)
{}
void operator()(std::string const& val) { feature_->put(name_, tr_.transcode(val.data(), val.length())); }
void operator()(bool const& val) { feature_->put(name_, static_cast<mapnik::value_bool>(val)); }
void operator()(int64_t const& val) { feature_->put(name_, static_cast<mapnik::value_integer>(val)); }
void operator()(uint64_t const& val) { feature_->put(name_, static_cast<mapnik::value_integer>(val)); }
void operator()(double const& val) { feature_->put(name_, static_cast<mapnik::value_double>(val)); }
void operator()(float const& val) { feature_->put(name_, static_cast<mapnik::value_double>(val)); }
};
struct mvt_layer
{
// We have to store the features as strings because they go out of scope otherwise (leading to PBF parsing
// errors).
std::vector<std::string> features_;
size_t feature_index_ = 0;
std::vector<std::string> keys_;
std::vector<pbf_attr_value_type> values_;
std::size_t num_keys_ = 0;
std::size_t num_values_ = 0;
double tile_x_;
double tile_y_;
double resolution_;
double scale_ = 0;
std::string name_;
uint32_t extent_ = 4096;
mvt_io& io_;
public:
explicit mvt_layer(mvt_io& io);
void add_feature(const protozero::data_view& feature);
bool has_features() const;
void add_key(std::string&& key);
void add_value(pbf_attr_value_type value);
void set_name(std::string&& name);
void set_extent(uint32_t extent);
mapnik::feature_ptr next_feature();
uint32_t extent() const;
void finish_reading();
};
protozero::pbf_reader reader_;
mapnik::context_ptr context_;
double tile_x_;
double tile_y_;
double resolution_;
std::string layer_name_;
std::unique_ptr<mvt_layer> layer_;
mapnik::transcoder tr_;
// Read a layer from PBF. Returns true if requested layer was parsed.
bool read_layer(protozero::pbf_message<mvt_message::layer>& l);
public:
explicit mvt_io(std::string&& data,
mapnik::context_ptr const& ctx,
const uint32_t x,
const uint32_t y,
const uint32_t zoom,
std::string layer_name);
mapnik::feature_ptr next();
};
#endif // PLUGINS_INPUT_MBTILES_VECTOR_MVT_IO_HPP_