Text to speech engine implementation

PdfForQtViewer/pdftexttospeech.h

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+//    Copyright (C) 2020 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 PDFTEXTTOSPEECH_H
+#define PDFTEXTTOSPEECH_H
+
+#include "pdftextlayout.h"
+
+#include <QObject>
+
+class QSlider;
+class QComboBox;
+class QToolButton;
+class QTextToSpeech;
+
+namespace pdf
+{
+class PDFDocument;
+class PDFDrawWidgetProxy;
+}
+
+namespace pdfviewer
+{
+class PDFViewerSettings;
+
+/// Text to speech engine used to reading the document
+class PDFTextToSpeech : public QObject
+{
+    Q_OBJECT
+
+private:
+    using BaseClass = QObject;
+
+public:
+    explicit PDFTextToSpeech(QObject* parent);
+
+    enum State
+    {
+        Invalid,    ///< Text to speech engine is invalid (maybe bad engine)
+        NoDocument, ///< No document to read
+        Ready,      ///< Ready to read the document contents
+        Playing,    ///< Document is being read
+        Paused,     ///< User paused the reading
+        Error       ///< Error occured in text to speech engine
+    };
+
+    /// Returns true, if text to speech engine is valid and can be used
+    /// to synthetise text.
+    bool isValid() const;
+
+    /// Sets active document to text to speech engine
+    void setDocument(const pdf::PDFDocument* document);
+
+    /// Apply settings to the reader
+    void setSettings(const PDFViewerSettings* viewerSettings);
+
+    /// Set draw proxy
+    void setProxy(const pdf::PDFDrawWidgetProxy* proxy);
+
+    /// Initialize the ui, which is used
+    void initializeUI(QComboBox* speechLocaleComboBox,
+                      QComboBox* speechVoiceComboBox,
+                      QSlider* speechRateEdit,
+                      QSlider* speechVolumeEdit,
+                      QSlider* speechPitchEdit,
+                      QToolButton* speechPlayButton,
+                      QToolButton* speechPauseButton,
+                      QToolButton* speechStopButton,
+                      QToolButton* speechSynchronizeButton);
+
+private:
+    /// Updates UI controls depending on the state
+    void updateUI();
+
+    /// Stop the engine, if it is reading
+    void stop();
+
+    void setLocale(const QString& locale);
+    void setVoice(const QString& voice);
+    void setRate(const double rate);
+    void setPitch(const double pitch);
+    void setVolume(const double volume);
+
+    void onLocaleChanged();
+    void onVoiceChanged();
+    void onRateChanged(int rate);
+    void onPitchChanged(int pitch);
+    void onVolumeChanged(int volume);
+
+    void onPlayClicked();
+    void onPauseClicked();
+    void onStopClicked();
+
+    void updatePlay();
+    void updateToNextPage(pdf::PDFInteger pageIndex);
+
+    QTextToSpeech* m_textToSpeech;
+    const pdf::PDFDocument* m_document;
+    const pdf::PDFDrawWidgetProxy* m_proxy;
+    State m_state;
+    bool m_initialized;
+
+    QComboBox* m_speechLocaleComboBox;
+    QComboBox* m_speechVoiceComboBox;
+    QSlider* m_speechRateEdit;
+    QSlider* m_speechVolumeEdit;
+    QSlider* m_speechPitchEdit;
+    QToolButton* m_speechPlayButton;
+    QToolButton* m_speechPauseButton;
+    QToolButton* m_speechStopButton;
+    QToolButton* m_speechSynchronizeButton;
+
+    pdf::PDFTextLayout m_currentTextLayout; ///< Text layout for actual page
+    pdf::PDFTextFlows m_textFlows; ///< Text flows for actual page
+    size_t m_currentTextFlowIndex = 0; ///< Index of current text flow
+    pdf::PDFInteger m_currentPage = 0; ///< Current page
+};
+
+}   // namespace pdfviewer
+
+#endif // PDFTEXTTOSPEECH_H