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+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the examples of QtDataVis3D.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef SPECTRUMANALYSER_H
+#define SPECTRUMANALYSER_H
+
+#include <QByteArray>
+#include <QObject>
+#include <QVector>
+
+#include "frequencyspectrum.h"
+#include "spectrum.h"
+
+#include "FFTRealFixLenParam.h"
+
+QT_FORWARD_DECLARE_CLASS(QAudioFormat)
+QT_FORWARD_DECLARE_CLASS(QThread)
+
+class FFTRealWrapper;
+
+class SpectrumAnalyserThreadPrivate;
+
+/**
+ * Implementation of the spectrum analysis which can be run in a
+ * separate thread.
+ */
+class SpectrumAnalyserThread : public QObject
+{
+    Q_OBJECT
+
+public:
+    SpectrumAnalyserThread(QObject *parent);
+    ~SpectrumAnalyserThread();
+
+public slots:
+    void setWindowFunction(WindowFunction type);
+    void calculateSpectrum(const QByteArray &buffer,
+                           int inputFrequency,
+                           int bytesPerSample);
+
+signals:
+    void calculationComplete(const FrequencySpectrum &spectrum);
+
+private:
+    void calculateWindow();
+
+private:
+    FFTRealWrapper*                             m_fft;
+
+    const int                                   m_numSamples;
+
+    WindowFunction                              m_windowFunction;
+
+    typedef FFTRealFixLenParam::DataType        DataType;
+
+    QVector<DataType>                           m_window;
+
+    QVector<DataType>                           m_input;
+    QVector<DataType>                           m_output;
+
+    FrequencySpectrum                           m_spectrum;
+
+#ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD
+    QThread*                                    m_thread;
+#endif
+};
+
+/**
+ * Class which performs frequency spectrum analysis on a window of
+ * audio samples, provided to it by the Engine.
+ */
+class SpectrumAnalyser : public QObject
+{
+    Q_OBJECT
+
+public:
+    SpectrumAnalyser(QObject *parent = 0);
+    ~SpectrumAnalyser();
+
+public:
+    /*
+     * Set the windowing function which is applied before calculating the FFT
+     */
+    void setWindowFunction(WindowFunction type);
+
+    /*
+     * Calculate a frequency spectrum
+     *
+     * \param buffer       Audio data
+     * \param format       Format of audio data
+     *
+     * Frequency spectrum is calculated asynchronously.  The result is returned
+     * via the spectrumChanged signal.
+     *
+     * An ongoing calculation can be cancelled by calling cancelCalculation().
+     *
+     */
+    void calculate(const QByteArray &buffer, const QAudioFormat &format);
+
+    /*
+     * Check whether the object is ready to perform another calculation
+     */
+    bool isReady() const;
+
+    /*
+     * Cancel an ongoing calculation
+     *
+     * Note that cancelling is asynchronous.
+     */
+    void cancelCalculation();
+
+signals:
+    void spectrumChanged(const FrequencySpectrum &spectrum);
+
+private slots:
+    void calculationComplete(const FrequencySpectrum &spectrum);
+
+private:
+    void calculateWindow();
+
+private:
+
+    SpectrumAnalyserThread*    m_thread;
+
+    enum State {
+        Idle,
+        Busy,
+        Cancelled
+    };
+
+    State              m_state;
+};
+
+#endif // SPECTRUMANALYSER_H
+