mirror of https://github.com/JakubMelka/PDF4QT.git
100 lines
3.8 KiB
C++
100 lines
3.8 KiB
C++
// Copyright (C) 2020-2021 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 PDFOPTIMIZER_H
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#define PDFOPTIMIZER_H
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#include "pdfdocument.h"
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#include <QObject>
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namespace pdf
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{
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/// Class for optimalizing documents. Can examine object structure and it's dependencies,
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/// and remove unused objects, merge same objects, or even recompress some streams
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/// to achieve better optimization ratio. Optimization is configurable, user can specify,
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/// which optimization steps should be done and which not.
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class PDF4QTLIBSHARED_EXPORT PDFOptimizer : public QObject
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{
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Q_OBJECT
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public:
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enum OptimizationFlag
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{
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None = 0x0000, ///< No optimization is performed
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DereferenceSimpleObjects = 0x0001, ///< If simple objects are referenced (such as integers, bools, etc.), then they are dereferenced
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RemoveNullObjects = 0x0002, ///< Remove null objects from dictionary entries
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RemoveUnusedObjects = 0x0004, ///< Remove not referenced objects
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MergeIdenticalObjects = 0x0008, ///< Merge identical objects
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ShrinkObjectStorage = 0x0010, ///< Shrink object storage, so unused objects are filled with used (and generation number increased)
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RecompressFlateStreams = 0x0020, ///< Flate streams are recompressed with maximal compression
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All = 0xFFFF, ///< All optimizations turned on
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};
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Q_DECLARE_FLAGS(OptimizationFlags, OptimizationFlag)
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explicit PDFOptimizer(OptimizationFlags flags, QObject* parent);
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/// Set document, which should be optimalized
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/// \param document Document to optimalize
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void setDocument(const PDFDocument* document) { setStorage(document->getStorage()); }
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/// Set storage directly (storage must be valid and filled with objects)
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/// \param storage Storage
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void setStorage(const PDFObjectStorage& storage) { m_storage = storage; }
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/// Perform document optimalization. During optimization process, various
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/// signals are emitted to view progress.
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void optimize();
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/// Returns object storage used for optimization
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const PDFObjectStorage& getStorage() const { return m_storage; }
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/// Returns object storage by move semantics, old object storage is destroyed
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PDFObjectStorage takeStorage() { return qMove(m_storage); }
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/// Returns optimized document. Object storage is cleared after
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/// this function call.
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PDFDocument takeOptimizedDocument() { return PDFDocument(qMove(m_storage), PDFVersion(2, 0)); }
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OptimizationFlags getFlags() const;
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void setFlags(OptimizationFlags flags);
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signals:
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void optimizationStarted();
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void optimizationProgress(QString progressText);
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void optimizationFinished();
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private:
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bool performDereferenceSimpleObjects();
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bool performRemoveNullObjects();
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bool performRemoveUnusedObjects();
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bool performMergeIdenticalObjects();
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bool performShrinkObjectStorage();
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bool performRecompressFlateStreams();
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OptimizationFlags m_flags;
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PDFObjectStorage m_storage;
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};
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} // namespace pdf
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Q_DECLARE_OPERATORS_FOR_FLAGS(pdf::PDFOptimizer::OptimizationFlags)
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#endif // PDFOPTIMIZER_H
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