spectrograph.h Example File

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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