mirror of https://github.com/JakubMelka/PDF4QT.git
98 lines
3.4 KiB
C++
98 lines
3.4 KiB
C++
// Copyright (C) 2018-2021 Jakub Melka
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//
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// This file is part of Pdf4Qt.
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//
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// Pdf4Qt is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// with the written consent of the copyright owner, any later version.
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//
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// Pdf4Qt 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
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// GNU 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 License
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// along with Pdf4Qt. If not, see <https://www.gnu.org/licenses/>.
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#ifndef PDFNUMBERTREELOADER_H
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#define PDFNUMBERTREELOADER_H
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#include "pdfdocument.h"
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#include <vector>
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namespace pdf
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{
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/// This class can load a number tree into the array
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template<typename Type>
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class PDFNumberTreeLoader
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{
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public:
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explicit PDFNumberTreeLoader() = delete;
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using Objects = std::vector<Type>;
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/// Parses the number tree and loads its items into the array. Some errors are ignored,
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/// e.g. when kid is null. Type must contain methods to load object array.
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static Objects parse(const PDFObjectStorage* storage, const PDFObject& root)
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{
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Objects result;
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// First, try to load items from the tree into the array
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parseImpl(result, storage, root);
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// Array may not be sorted. Sort it using comparison operator for Type.
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std::stable_sort(result.begin(), result.end());
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return result;
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}
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private:
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static void parseImpl(Objects& objects, const PDFObjectStorage* storage, const PDFObject& root)
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{
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if (const PDFDictionary* dictionary = storage->getDictionaryFromObject(root))
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{
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// First, load the objects into the array
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const PDFObject& numberedItems = storage->getObject(dictionary->get("Nums"));
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if (numberedItems.isArray())
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{
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const PDFArray* numberedItemsArray = numberedItems.getArray();
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const size_t count = numberedItemsArray->getCount() / 2;
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objects.reserve(objects.size() + count);
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for (size_t i = 0; i < count; ++i)
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{
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const size_t numberIndex = 2 * i;
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const size_t valueIndex = 2 * i + 1;
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const PDFObject& number = storage->getObject(numberedItemsArray->getItem(numberIndex));
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if (!number.isInt())
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{
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continue;
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}
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objects.emplace_back(Type::parse(number.getInteger(), storage, numberedItemsArray->getItem(valueIndex)));
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}
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}
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// Then, follow the kids
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const PDFObject& kids = storage->getObject(dictionary->get("Kids"));
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if (kids.isArray())
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{
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const PDFArray* kidsArray = kids.getArray();
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const size_t count = kidsArray->getCount();
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for (size_t i = 0; i < count; ++i)
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{
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parseImpl(objects, storage, kidsArray->getItem(i));
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}
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}
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}
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}
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};
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} // namespace pdf
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#endif // PDFNUMBERTREELOADER_H
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