Shading: Axial shading (first part)

PdfForQtLib/sources/pdfpattern.h

@@ -0,0 +1,158 @@
+//    Copyright (C) 2019 Jakub Melka
+//
+//    This file is part of PdfForQt.
+//
+//    PdfForQt 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.
+//
+//    PdfForQt 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 PDFForQt.  If not, see <https://www.gnu.org/licenses/>.
+
+#ifndef PDFPATTERN_H
+#define PDFPATTERN_H
+
+#include "pdfobject.h"
+#include "pdffunction.h"
+#include "pdfcolorspaces.h"
+
+#include <QMatrix>
+
+#include <memory>
+
+namespace pdf
+{
+class PDFPattern;
+
+using PDFPatternPtr = std::shared_ptr<PDFPattern>;
+
+enum class PatternType
+{
+    Invalid = 0,
+    Tiling = 1,
+    Shading = 2,
+};
+
+enum class ShadingType
+{
+    Invalid = 0,
+    Function = 1,
+    Axial = 2,
+    Radial = 3,
+    FreeFormGouradTriangle = 4,
+    LatticeFormGouradTriangle = 5,
+    CoonsPatchMesh = 6,
+    TensorProductPatchMesh = 7
+};
+
+/// Represents tiling/shading pattern
+class PDFPattern
+{
+public:
+    explicit PDFPattern() = default;
+    virtual ~PDFPattern() = default;
+
+    virtual PatternType getType() const = 0;
+
+    /// Returns bounding box in the shadings target coordinate system (not in
+    /// pattern coordinate system).
+    const QRectF& getBoundingBox() const { return m_boundingBox; }
+
+    /// Returns transformation matrix from pattern space to the default
+    /// target space.
+    const QMatrix& getMatrix() const { return m_matrix; }
+
+    /// Create pattern from the object. If error occurs, exception is thrown
+    /// \param colorSpaceDictionary Color space dictionary
+    /// \param document Document, owning the pdf object
+    /// \param object Object defining the pattern
+    static PDFPatternPtr createPattern(const PDFDictionary* colorSpaceDictionary, const PDFDocument* document, const PDFObject& object);
+
+    /// Create shading pattern from the object. If error occurs, exception is thrown
+    /// \param colorSpaceDictionary Color space dictionary
+    /// \param document Document, owning the pdf object
+    /// \param object Object defining the shading
+    /// \param matrix Matrix converting reference coordinate system to the device coordinate system
+    /// \param patternGraphicState Pattern graphic state
+    /// \param ignoreBackgroundColor If set, then ignores background color, even if it is present
+    static PDFPatternPtr createShadingPattern(const PDFDictionary* colorSpaceDictionary,
+                                              const PDFDocument* document,
+                                              const PDFObject& shadingObject,
+                                              const QMatrix& matrix,
+                                              const PDFObject& patternGraphicState,
+                                              bool ignoreBackgroundColor);
+
+private:
+    QRectF m_boundingBox;
+    QMatrix m_matrix;
+};
+
+/// Shading pattern - smooth color distribution along the pattern's space
+class PDFShadingPattern : public PDFPattern
+{
+public:
+    explicit PDFShadingPattern() = default;
+
+    virtual PatternType getType() const override;
+    virtual ShadingType getShadingType() const = 0;
+
+    /// Returns patterns graphic state. This state must be applied before
+    /// the shading pattern is painted to the target device.
+    const PDFObject& getPatternGraphicState() const { return m_patternGraphicState; }
+
+    /// Returns color space of the pattern.
+    const PDFAbstractColorSpace* getColorSpace() const;
+
+    /// Returns patterns background color (if pattern has background color).
+    /// If pattern has not background color, then invalid color is returned.
+    const QColor& getBackgroundColor() const { return m_backgroundColor; }
+
+    /// Returns true, if shading pattern should be anti-aliased
+    bool isAntialiasing() const { return m_antiAlias; }
+
+private:
+    friend class PDFPattern;
+
+    PDFObject m_patternGraphicState;
+    PDFColorSpacePointer m_colorSpace;
+    QColor m_backgroundColor;
+    bool m_antiAlias = false;
+};
+
+class PDFSingleDimensionShading : public PDFShadingPattern
+{
+public:
+    explicit PDFSingleDimensionShading() = default;
+
+private:
+    friend class PDFPattern;
+
+    std::vector<PDFFunctionPtr> m_functions;
+    QPointF m_startPoint;
+    QPointF m_endPoint;
+    PDFReal m_domainStart = 0.0;
+    PDFReal m_domainEnd = 1.0;
+    bool m_extendStart = false;
+    bool m_extendEnd = false;
+};
+
+class PDFAxialShading : public PDFSingleDimensionShading
+{
+public:
+    explicit PDFAxialShading() = default;
+
+    virtual ShadingType getShadingType() const override;
+
+private:
+    friend class PDFPattern;
+};
+
+}   // namespace pdf
+
+#endif // PDFPATTERN_H