92 lines
3 KiB
C++
92 lines
3 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) 2021 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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// mapnik
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#include <mapnik/image_reader.hpp>
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#include <mapnik/image_util.hpp>
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#include <mapnik/factory.hpp>
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namespace mapnik {
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inline std::optional<std::string> type_from_bytes(char const* data, size_t size)
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{
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unsigned char const* header = reinterpret_cast<unsigned char const*>(data);
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if (size >= 4)
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{
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unsigned int magic = (header[0] << 24) | (header[1] << 16) | (header[2] << 8) | header[3];
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if (magic == 0x89504E47U)
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{
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return "png";
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}
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else if (magic == 0x49492A00U || magic == 0x4D4D002AU)
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{
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return "tiff";
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}
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}
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if (size >= 2)
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{
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unsigned int magic = ((header[0] << 8) | header[1]) & 0xffff;
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if (magic == 0xffd8)
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{
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return "jpeg";
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}
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}
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if (size >= 12)
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{
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if (header[0] == 'R' && header[1] == 'I' && header[2] == 'F' && header[3] == 'F' && header[8] == 'W' &&
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header[9] == 'E' && header[10] == 'B' && header[11] == 'P')
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{
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return "webp";
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}
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}
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return std::nullopt;
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}
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image_reader* get_image_reader(char const* data, size_t size)
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{
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const auto type = type_from_bytes(data, size);
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if (type.has_value())
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return factory<image_reader, std::string, char const*, size_t>::instance().create_object(*type, data, size);
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else
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throw image_reader_exception("image_reader: can't determine type from input data");
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}
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image_reader* get_image_reader(std::string const& filename, std::string const& type)
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{
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return factory<image_reader, std::string, std::string const&>::instance().create_object(type, filename);
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}
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image_reader* get_image_reader(std::string const& filename)
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{
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const auto type = type_from_filename(filename);
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if (type.has_value())
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{
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return factory<image_reader, std::string, std::string const&>::instance().create_object(*type, filename);
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}
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else
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{
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throw image_reader_exception("image_reader: can't determine type from input data");
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}
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}
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} // namespace mapnik
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