Qt Reference Documentation

# spectrograph.h Example File

demos/spectrum/app/spectrograph.h

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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 analyzed 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