Issue #118: First part of splitting

Pdf4QtLibCore/sources/pdfpagenavigation.h

@@ -0,0 +1,112 @@
+//    Copyright (C) 2020-2021 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
+//    with the written consent of the copyright owner, 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 PDFPAGENAVIGATION_H
+#define PDFPAGENAVIGATION_H
+
+#include "pdfpage.h"
+#include "pdfcatalog.h"
+#include "pdfdocument.h"
+#include "pdfpagetransition.h"
+#include "pdfaction.h"
+
+#include <QObject>
+
+namespace pdf
+{
+
+/// Page navigation node for subpage navigation.
+class PDFNavigationNode
+{
+public:
+    explicit PDFNavigationNode() = default;
+
+    PDFActionPtr getPreviousAction() const;
+    PDFActionPtr getNextAction() const;
+
+    PDFObjectReference getPreviousNode() const;
+    PDFObjectReference getNextNode() const;
+
+    PDFReal getDuration() const;
+
+    /// Parses navigation node. If error occurs, then empty optional
+    /// item is returned.
+    /// \param storage Storage
+    /// \param object Object
+    static std::optional<PDFNavigationNode> parse(const PDFObjectStorage* storage, PDFObject object);
+
+private:
+    PDFActionPtr m_previousAction;
+    PDFActionPtr m_nextAction;
+    PDFObjectReference m_previousNode;
+    PDFObjectReference m_nextNode;
+    PDFReal m_duration = 0.0;
+};
+
+/// Navigation object, which helps to navigate trough document.
+/// It also handles subpage navigation, if subpage navigation
+/// steps are present.
+class PDF4QTLIBSHARED_EXPORT PDFPageNavigation : public QObject
+{
+    Q_OBJECT
+
+public:
+    explicit PDFPageNavigation(const PDFDocument* document, QObject* parent);
+
+    /// Navigates to specified page. Page index must be valid.
+    /// \param pageIndex Page index
+    void navigateToPage(size_t pageIndex);
+
+    /// Navigates forward. If subpage navigation is present,
+    /// navigates to next page navigation node. Otherwise
+    /// navigates to next page.
+    void navigateForward();
+
+    /// Navigates backward. If subpage navigation is present,
+    /// navigates to previous page navigation node. Otherwise
+    /// navigates to previous page.
+    void navigateBackward();
+
+signals:
+    /// This signal is emitted, if subpage navigation is requested.
+    void actionTriggered(const PDFAction* action);
+
+    /// This signal is emitted, if navigation to another page is required.
+    /// Page index is always valid. If document contains no pages, then
+    /// this signal is never emitted. Also, transition is always a valid
+    /// object (not null pointer).
+    void pageChangeRequest(const size_t pageIndex, const PDFPageTransition* transition);
+
+private:
+
+    enum class Direction
+    {
+        Forward,  ///< We navigate forward
+        Backward  ///< We navigate backward
+    };
+
+    void executeNavigationNode(Direction direction);
+
+    size_t m_currentPageIndex;
+    std::optional<PDFNavigationNode> m_currentNavigationNode;
+    PDFPageTransition m_transition;
+    const PDFDocument* m_document;
+};
+
+}   // namespace pdf
+
+#endif // PDFPAGENAVIGATION_H