xref: /external/webkit/Source/WebCore/webaudio/AudioParam.cpp

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 *     notice, this list of conditions and the following disclaimer in the
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 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "AudioParam.h"

#include <wtf/MathExtras.h>

namespace WebCore {

const double AudioParam::DefaultSmoothingConstant = 0.05;
const double AudioParam::SnapThreshold = 0.001;

void AudioParam::setValue(float value)
{
    // Check against JavaScript giving us bogus floating-point values.
    // Don't ASSERT, since this can happen if somebody writes bad JS.
    if (!isnan(value) && !isinf(value))
        m_value = value;
}

bool AudioParam::smooth()
{
    if (m_smoothedValue == m_value) {
        // Smoothed value has already approached and snapped to value.
        return true;
    }

    // Exponential approach
    m_smoothedValue += (m_value - m_smoothedValue) * m_smoothingConstant;

    // If we get close enough then snap to actual value.
    if (fabs(m_smoothedValue - m_value) < SnapThreshold) // FIXME: the threshold needs to be adjustable depending on range - but this is OK general purpose value.
        m_smoothedValue = m_value;

    return false;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)