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    37 

    38 #ifndef LEVELMETER_H

    39 #define LEVELMETER_H

    40 

    41 #include <QTime>

    42 #include <QWidget>

    43 

    44 /**

    45  * Widget which displays a vertical audio level meter, indicating the

    46  * RMS and peak levels of the window of audio samples most recently analysed

    47  * by the Engine.

    48  */

    49 class LevelMeter : public QWidget {

    50     Q_OBJECT

    51 public:

    52     LevelMeter(QWidget *parent = 0);

    53     ~LevelMeter();

    54 

    55     void paintEvent(QPaintEvent *event);

    56 

    57 public slots:

    58     void reset();

    59     void levelChanged(qreal rmsLevel, qreal peakLevel, int numSamples);

    60 

    61 private slots:

    62     void redrawTimerExpired();

    63 

    64 private:

    65     /**

    66      * Height of RMS level bar.

    67      * Range 0.0 - 1.0.

    68      */

    69     qreal m_rmsLevel;

    70 

    71     /**

    72      * Most recent peak level.

    73      * Range 0.0 - 1.0.

    74      */

    75     qreal m_peakLevel;

    76 

    77     /**

    78      * Height of peak level bar.

    79      * This is calculated by decaying m_peakLevel depending on the

    80      * elapsed time since m_peakLevelChanged, and the value of m_decayRate.

    81      */

    82     qreal m_decayedPeakLevel;

    83 

    84     /**

    85      * Time at which m_peakLevel was last changed.

    86      */

    87     QTime m_peakLevelChanged;

    88 

    89     /**

    90      * Rate at which peak level bar decays.

    91      * Expressed in level units / millisecond.

    92      */

    93     qreal m_peakDecayRate;

    94 

    95     /**

    96      * High watermark of peak level.

    97      * Range 0.0 - 1.0.

    98      */

    99     qreal m_peakHoldLevel;

   100 

   101     /**

   102      * Time at which m_peakHoldLevel was last changed.

   103      */

   104     QTime m_peakHoldLevelChanged;

   105 

   106     QTimer *m_redrawTimer;

   107 

   108     QColor m_rmsColor;

   109     QColor m_peakColor;

   110 

   111 };

   112 

   113 #endif // LEVELMETER_H