levelmeter.h Example File

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#ifndef LEVELMETER_H
#define LEVELMETER_H
#include <QTime>
#include <QWidget>
/**
 * Widget which displays a vertical audio level meter, indicating the
 * RMS and peak levels of the window of audio samples most recently analyzed
 * by the Engine.
 */
class LevelMeter : public QWidget
{
    Q_OBJECT
public:
    explicit LevelMeter(QWidget *parent = 0);
    ~LevelMeter();
    void paintEvent(QPaintEvent *event) override;
public slots:
    void reset();
    void levelChanged(qreal rmsLevel, qreal peakLevel, int numSamples);
private slots:
    void redrawTimerExpired();
private:
    /**
     * Height of RMS level bar.
     * Range 0.0 - 1.0.
     */
    qreal m_rmsLevel;
    /**
     * Most recent peak level.
     * Range 0.0 - 1.0.
     */
    qreal m_peakLevel;
    /**
     * Height of peak level bar.
     * This is calculated by decaying m_peakLevel depending on the
     * elapsed time since m_peakLevelChanged, and the value of m_decayRate.
     */
    qreal m_decayedPeakLevel;
    /**
     * Time at which m_peakLevel was last changed.
     */
    QTime m_peakLevelChanged;
    /**
     * Rate at which peak level bar decays.
     * Expressed in level units / millisecond.
     */
    qreal m_peakDecayRate;
    /**
     * High watermark of peak level.
     * Range 0.0 - 1.0.
     */
    qreal m_peakHoldLevel;
    /**
     * Time at which m_peakHoldLevel was last changed.
     */
    QTime m_peakHoldLevelChanged;
    QTimer *m_redrawTimer;
    QColor m_rmsColor;
    QColor m_peakColor;
};
#endif // LEVELMETER_H