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diff --git a/tests/spectrum/spectrumapp/spectrumanalyser.h b/tests/spectrum/spectrumapp/spectrumanalyser.h
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+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc
+** All rights reserved.
+** For any questions to Digia, please use contact form at http://qt.digia.com
+**
+** This file is part of the QtDataVis3D module.
+**
+** Licensees holding valid Qt Enterprise licenses may use this file in
+** accordance with the Qt Enterprise License Agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.
+**
+** If you have questions regarding the use of this file, please use
+** contact form at http://qt.digia.com
+**
+****************************************************************************/
+
+#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
+