- Qt 5.3
- Qt Multimedia
- Spectrum Example
- spectrograph.h Example File
- Qt 5.3.2 Reference Documentation

# spectrograph.h Example File

spectrum/app/spectrograph.h

    /****************************************************************************
    **
    ** 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 the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** 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
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    #ifndef SPECTROGRAPH_H
    #define SPECTROGRAPH_H

    #include "frequencyspectrum.h"

    #include <QWidget>

    /**
     * Widget which displays a spectrograph showing the frequency spectrum
     * of the window of audio samples most recently analyzed by the Engine.
     */
    class Spectrograph : public QWidget
    {
        Q_OBJECT

    public:
        explicit Spectrograph(QWidget *parent = 0);
        ~Spectrograph();

        void setParams(int numBars, qreal lowFreq, qreal highFreq);

        // QObject
        void timerEvent(QTimerEvent *event);

        // QWidget
        void paintEvent(QPaintEvent *event);
        void mousePressEvent(QMouseEvent *event);

    signals:
        void infoMessage(const QString &message, int intervalMs);

    public slots:
        void reset();
        void spectrumChanged(const FrequencySpectrum &spectrum);

    private:
        int barIndex(qreal frequency) const;
        QPair<qreal, qreal> barRange(int barIndex) const;
        void updateBars();

        void selectBar(int index);

    private:
        struct Bar {
            Bar() : value(0.0), clipped(false) { }
            qreal   value;
            bool    clipped;
        };

        QVector<Bar>        m_bars;
        int                 m_barSelected;
        int                 m_timerId;
        qreal               m_lowFreq;
        qreal               m_highFreq;
        FrequencySpectrum   m_spectrum;
    };

    #endif // SPECTROGRAPH_H