spectrograph.h Example File

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 #ifndef SPECTROGRAPH_H
 #define SPECTROGRAPH_H

 #include <QWidget>
 #include "frequencyspectrum.h"

 QT_FORWARD_DECLARE_CLASS(QMouseEvent)

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