PDF4QT/Pdf4QtLib/sources/pdfblendfunction.h

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// Copyright (C) 2019-2020 Jakub Melka
//
// This file is part of Pdf4Qt.
//
// Pdf4Qt is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Pdf4Qt is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with Pdf4Qt. If not, see <https://www.gnu.org/licenses/>.
#ifndef PDFBLENDFUNCTION_H
#define PDFBLENDFUNCTION_H
#include "pdfglobal.h"
#include <QPainter>
namespace pdf
{
enum class BlendMode
{
// Separable blending modes
Normal, ///< Select source color, backdrop is ignored: B(source, dest) = source
Multiply, ///< Backdrop and source colors are multiplied: B(source, dest) = source * dest
Screen, ///< B(source, dest) = 1.0 - (1.0 - source) * (1.0 - dest) + source + dest - source * dest
Overlay, ///< B(source, dest) = HardLight(dest, source)
Darken, ///< Selects the darker of the colors. B(source, dest) = qMin(source, dest)
Lighten, ///< Selects the lighter of the colors. B(source, dest) = qMax(source, dest)
ColorDodge, ///< Brightens the backdrop color reflecting the source color. B(source, dest) = qMin(1.0, dest / (1.0 - source)), or 1.0, if source is 1.0
ColorBurn, ///< Darkens the backdrop color reflecting the source color. B(source, dest) = 1.0 - qMin(1.0, (1.0 - dest) / source), or 0.0, if source is 0.0
HardLight, ///< Multiply or screen the color, depending on the source value.
SoftLight, ///< Darkens or lightens the color, depending on the source value.
Difference, ///< Subtract the darker of colors from the lighter color. B(source, dest) = qAbs(source - dest)
Exclusion, ///< B(source, dest) = source + dest - 2 * source * dest
// Non-separable blending modes
Hue,
Saturation,
Color,
Luminosity,
// For compatibility - older PDF specification specifies Compatible mode, which is equal
// to normal. It should be recognized for sake of compatibility.
Compatible, ///< Equals to normal
// Invalid blending mode - for internal purposes only
Invalid
};
class PDFBlendModeInfo
{
public:
PDFBlendModeInfo() = delete;
/// Returns blend mode from the specified string. If string is invalid,
/// then \p Invalid blend mode is returned.
/// \param name Name of the blend mode
static BlendMode getBlendMode(const QByteArray& name);
/// Returns true, if blend mode is supported by Qt drawing subsystem
/// \param mode Blend mode
static bool isSupportedByQt(BlendMode mode);
/// Returns composition mode for Qt drawing subsystem from blend mode defined
/// in PDF standard. If blend mode is not supported by Qt drawing subsystem, then default
/// composition mode is returned.
/// \param mode Blend mode
static QPainter::CompositionMode getCompositionModeFromBlendMode(BlendMode mode);
/// Returns blend mode name
/// \param mode Blend mode
static QString getBlendModeName(BlendMode mode);
/// Returns blend mode translated name
/// \param mode Blend mode
static QString getBlendModeTranslatedName(BlendMode mode);
/// Returns vector of all blend modes, excluding duplicate ones (for example,
/// Compatible mode is equal to Normal blend mode)
static std::vector<BlendMode> getBlendModes();
};
} // namespace pdf
#endif // PDFBLENDFUNCTION_H