Color spaces, beginning of painting

PdfForQtLib/sources/pdfrenderer.h

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+//    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 PDFRENDERER_H
+#define PDFRENDERER_H
+
+#include "pdfpage.h"
+#include "pdfcolorspaces.h"
+
+#include <QMatrix>
+#include <QSharedPointer>
+
+#include <stack>
+
+namespace pdf
+{
+
+enum RenderErrorType
+{
+    Error,
+    NotImplemented
+};
+
+struct PDFRenderError
+{
+    explicit PDFRenderError() = default;
+    explicit PDFRenderError(RenderErrorType type, QString message) :
+        type(type),
+        message(std::move(message))
+    {
+
+    }
+
+    RenderErrorType type = RenderErrorType::Error;
+    QString message;
+};
+
+/// Renders the PDF page on the painter, or onto an image.
+class PDFRenderer
+{
+public:
+    explicit PDFRenderer(const PDFDocument* document);
+
+    enum Feature
+    {
+        Antialasing,        ///< Antialiasing for lines, shapes, etc.
+        TextAntialiasing,   ///< Antialiasing for drawing text
+        SmoothImages        ///< Adjust images to the device space using smooth transformation (slower, but better performance quality)
+    };
+
+    Q_DECLARE_FLAGS(Features, Feature)
+
+    /// Paints desired page onto the painter. Page is painted in the rectangle using best-fit method.
+    /// If the page doesn't exist, then error is returned. No exception is thrown. Rendering errors
+    /// are reported and returned in the error list. If no error occured, empty list is returned.
+    /// \param painter Painter
+    /// \param rectangle Paint area for the page
+    /// \param pageIndex Index of the page to be painted
+    QList<PDFRenderError> render(QPainter* painter, const QRectF& rectangle, size_t pageIndex) const;
+
+private:
+    const PDFDocument* m_document;
+    Features m_features;
+};
+
+/// Process the contents of the page.
+class PDFPageContentProcessor
+{
+public:
+    explicit PDFPageContentProcessor(const PDFPage* page, const PDFDocument* document);
+
+    /// Process the contents of the page
+    QList<PDFRenderError> processContents();
+
+protected:
+    /// Process the content stream
+    QList<PDFRenderError> processContentStream(const PDFStream* stream);
+
+    /// Represents graphic state of the PDF (holding current graphic state parameters).
+    /// Please see PDF Reference 1.7, Chapter 4.3 "Graphic State"
+    class PDFPageContentProcessorState
+    {
+    public:
+        explicit PDFPageContentProcessorState();
+        ~PDFPageContentProcessorState();
+
+    private:
+        QMatrix m_currentTransformationMatrix;
+        QSharedPointer<PDFAbstractColorSpace> m_fillColorSpace;
+        QSharedPointer<PDFAbstractColorSpace> m_strokeColorSpace;
+        QColor m_fillColor;
+        QColor m_strokeColor;
+        PDFReal m_lineWidth;
+        Qt::PenCapStyle m_lineCapStyle;
+        Qt::PenJoinStyle m_lineJoinStyle;
+        PDFReal m_mitterLimit;
+        QByteArray m_renderingIntent;
+        PDFReal m_flatness;
+        PDFReal m_smoothness;
+    };
+
+private:
+
+    const PDFPage* m_page;
+    const PDFDocument* m_document;
+
+    /// Stack with current graphic states
+    std::stack<PDFPageContentProcessorState> m_stack;
+};
+
+}   // namespace pdf
+
+Q_DECLARE_OPERATORS_FOR_FLAGS(pdf::PDFRenderer::Features)
+
+#endif // PDFRENDERER_H