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+/****************************************************************************
+**
+** 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.
+**
+** You may use this file under the terms of the BSD license as follows:
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are met:
+** - Redistributions of source code must retain the above copyright notice,
+**   this list of conditions and the following disclaimer.
+** - Redistributions in binary form must reproduce the above copyright notice,
+**   this list of conditions and the following disclaimer in the documentation
+**   and/or other materials provided with the distribution.
+** - Neither the name of Nokia Corporation and its Subsidiary(-ies) nor the
+**   names of its contributors may be used to endorse or promote products
+**   derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+** AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+** ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+** LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+** CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+** SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+** INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+** CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+** ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+** POSSIBILITY OF SUCH DAMAGE.
+**
+*****************************************************************************/
+
+#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