/****************************************************************************

**

** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the examples of the Qt Toolkit.

**

** $QT_BEGIN_LICENSE:BSD$

** You may use this file under the terms of the BSD license as follows:

**

**

** $QT_END_LICENSE$

**

#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 analysed

 * by the Engine.

 */

class LevelMeter : public QWidget {

    Q_OBJECT

public:

    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;

};

#endif // LEVELMETER_H