sdrangel/sdrbase/gui/levelmeter.h

/****************************************************************************
 * Copyright (C) 2016 Edouard Griffiths, F4EXB
 * Modifications made to:
 * - use the widget horizontally
 * - differentiate each area with a different color
 * - allow overload by 25% with indication of 100% threshold and overload
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
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**
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**     notice, this list of conditions and the following disclaimer.
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**     distribution.
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****************************************************************************/

#ifndef SDRBASE_GUI_LEVELMETER_H_
#define SDRBASE_GUI_LEVELMETER_H_

#include <QTime>
#include <QWidget>
#include <dsp/dsptypes.h>

/**
 * 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);

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;
    QColor m_decayedPeakColor;

    void render(QPainter *painter);
};

#endif /* SDRBASE_GUI_LEVELMETER_H_ */