mirror of https://github.com/JakubMelka/PDF4QT.git
98 lines
4.0 KiB
C++
98 lines
4.0 KiB
C++
// Copyright (C) 2023 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 PDFIMAGECONVERSION_H
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#define PDFIMAGECONVERSION_H
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#include "pdfglobal.h"
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#include <QImage>
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namespace pdf
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{
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/// This class facilitates various image conversions,
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/// including transforming colored images into monochromatic (or bitonal) formats.
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class PDF4QTLIBSHARED_EXPORT PDFImageConversion
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{
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public:
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PDFImageConversion();
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enum class ConversionMethod
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{
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Automatic, ///< The threshold is determined automatically using an algorithm.
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Manual ///< The threshold is manually provided by the user.
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};
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/// Sets the image to be converted using the specified conversion method.
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/// This operation resets any previously converted image and the automatic threshold,
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/// thereby erasing all prior image data.
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/// \param image The image to be set for conversion.
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void setImage(QImage image);
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/// Sets the method for image conversion. Multiple methods are available
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/// for selection. If the manual method is chosen, an appropriate threshold
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/// must also be set by the user.
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/// \param method The conversion method to be used.
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void setConversionMethod(ConversionMethod method);
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/// Sets the manual threshold value. When a non-manual (e.g., automatic) conversion
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/// method is in use, this function will retain the manual threshold settings,
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/// but the conversion will utilize an automatically calculated threshold for the image.
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/// The manually set threshold is preserved and not overwritten. Therefore, if the
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/// manual conversion method is later selected, the previously established manual
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/// threshold will be applied.
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/// \param threshold The manual threshold value to be set.
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void setThreshold(int threshold);
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/// This method converts the image into a bitonal (monochromatic) format. If
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/// the automatic threshold calculation is enabled, it executes Otsu's 1D algorithm
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/// to determine the threshold. When the manual conversion method is selected,
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/// the automatic threshold calculation is bypassed, and the predefined manual threshold
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/// value is utilized instead. This method returns true if the conversion is
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/// successful, and false otherwise.
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bool convert();
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/// Returns the threshold used in image conversion. If the automatic conversion method is
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/// selected, this function should be called only after executing the convert() method;
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/// otherwise, it may return invalid data. The automatic threshold calculation is
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/// performed within the convert() method.
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/// \returns The threshold value used in image conversion.
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int getThreshold() const;
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/// Returns the converted image. This method should only be called after
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/// the convert() method has been executed, and additionally, only if the
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/// convert() method returns true. If these conditions are not met, the result
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/// is undefined.
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QImage getConvertedImage() const;
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private:
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int calculateOtsu1DThreshold() const;
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static constexpr int DEFAULT_THRESHOLD = 128;
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QImage m_image;
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QImage m_convertedImage;
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ConversionMethod m_conversionMethod = ConversionMethod::Automatic;
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int m_automaticThreshold = DEFAULT_THRESHOLD;
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int m_manualThreshold = DEFAULT_THRESHOLD;
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};
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} // namespace pdf
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#endif // PDFIMAGECONVERSION_H
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