Files
PDF4QT/Pdf4QtLibCore/sources/pdfoptimizer.h
2025-04-27 12:39:06 +02:00

105 lines
4.2 KiB
C++

// MIT License
//
// Copyright (c) 2018-2025 Jakub Melka and Contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#ifndef PDFOPTIMIZER_H
#define PDFOPTIMIZER_H
#include "pdfdocument.h"
#include <QObject>
namespace pdf
{
/// Class for optimalizing documents. Can examine object structure and it's dependencies,
/// and remove unused objects, merge same objects, or even recompress some streams
/// to achieve better optimization ratio. Optimization is configurable, user can specify,
/// which optimization steps should be done and which not.
class PDF4QTLIBCORESHARED_EXPORT PDFOptimizer : public QObject
{
Q_OBJECT
public:
enum OptimizationFlag
{
None = 0x0000, ///< No optimization is performed
DereferenceSimpleObjects = 0x0001, ///< If simple objects are referenced (such as integers, bools, etc.), then they are dereferenced
RemoveNullObjects = 0x0002, ///< Remove null objects from dictionary entries
RemoveUnusedObjects = 0x0004, ///< Remove not referenced objects
MergeIdenticalObjects = 0x0008, ///< Merge identical objects
ShrinkObjectStorage = 0x0010, ///< Shrink object storage, so unused objects are filled with used (and generation number increased)
RecompressFlateStreams = 0x0020, ///< Flate streams are recompressed with maximal compression
All = 0xFFFF, ///< All optimizations turned on
};
Q_DECLARE_FLAGS(OptimizationFlags, OptimizationFlag)
explicit PDFOptimizer(OptimizationFlags flags, QObject* parent);
/// Set document, which should be optimalized
/// \param document Document to optimalize
void setDocument(const PDFDocument* document) { setStorage(document->getStorage()); }
/// Set storage directly (storage must be valid and filled with objects)
/// \param storage Storage
void setStorage(const PDFObjectStorage& storage) { m_storage = storage; }
/// Perform document optimalization. During optimization process, various
/// signals are emitted to view progress.
void optimize();
/// Returns object storage used for optimization
const PDFObjectStorage& getStorage() const { return m_storage; }
/// Returns object storage by move semantics, old object storage is destroyed
PDFObjectStorage takeStorage() { return qMove(m_storage); }
/// Returns optimized document. Object storage is cleared after
/// this function call.
PDFDocument takeOptimizedDocument() { return PDFDocument(qMove(m_storage), PDFVersion(2, 0), QByteArray()); }
OptimizationFlags getFlags() const;
void setFlags(OptimizationFlags flags);
signals:
void optimizationStarted();
void optimizationProgress(QString progressText);
void optimizationFinished();
private:
bool performDereferenceSimpleObjects();
bool performRemoveNullObjects();
bool performRemoveUnusedObjects();
bool performMergeIdenticalObjects();
bool performShrinkObjectStorage();
bool performRecompressFlateStreams();
OptimizationFlags m_flags;
PDFObjectStorage m_storage;
};
} // namespace pdf
Q_DECLARE_OPERATORS_FOR_FLAGS(pdf::PDFOptimizer::OptimizationFlags)
#endif // PDFOPTIMIZER_H