mirror of https://github.com/JakubMelka/PDF4QT.git
95 lines
3.4 KiB
C++
95 lines
3.4 KiB
C++
// Copyright (C) 2019 Jakub Melka
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//
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// This file is part of PdfForQt.
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//
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// PdfForQt 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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// (at your option) any later version.
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//
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// PdfForQt 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 PDFForQt. If not, see <https://www.gnu.org/licenses/>.
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#ifndef PDFNAMETREELOADER_H
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#define PDFNAMETREELOADER_H
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#include "pdfdocument.h"
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#include <map>
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#include <functional>
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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 PDFNameTreeLoader
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{
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public:
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explicit PDFNameTreeLoader() = delete;
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using MappedObjects = std::map<QByteArray, Type>;
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using LoadMethod = std::function<Type(const PDFDocument*, const PDFObject&)>;
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/// Parses the name tree and loads its items into the map. Some errors are ignored,
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/// e.g. when kid is null. Objects are retrieved by \p loadMethod.
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/// \param document Document
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/// \param root Root of the name tree
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/// \param loadMethod Parsing method, which retrieves parsed object
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static MappedObjects parse(const PDFDocument* document, const PDFObject& root, const LoadMethod& loadMethod)
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{
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MappedObjects result;
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parseImpl(result, document, root, loadMethod);
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return result;
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}
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private:
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static void parseImpl(MappedObjects& objects, const PDFDocument* document, const PDFObject& root, const LoadMethod& loadMethod)
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{
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if (const PDFDictionary* dictionary = document->getDictionaryFromObject(root))
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{
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// Jakub Melka: First, load the objects into the map
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const PDFObject& namedItems = document->getObject(dictionary->get("Names"));
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if (namedItems.isArray())
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{
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const PDFArray* namedItemsArray = namedItems.getArray();
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const size_t count = namedItemsArray->getCount() / 2;
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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& name = document->getObject(namedItemsArray->getItem(numberIndex));
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if (!name.isString())
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{
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continue;
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}
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objects[name.getString()] = loadMethod(document, namedItemsArray->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 = document->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, document, kidsArray->getItem(i), loadMethod);
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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 // PDFNAMETREELOADER_H
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