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/*
* Copyright (C) 2010 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of Apple Computer, Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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 AudioParam_h
#define AudioParam_h
#include "PlatformString.h"
#include <math.h>
#include <sys/types.h>
#include <wtf/PassRefPtr.h>
#include <wtf/RefCounted.h>
namespace WebCore {
class AudioParam : public RefCounted<AudioParam> {
public:
static const double DefaultSmoothingConstant = 0.05;
static const double SnapThreshold = 0.001;
static PassRefPtr<AudioParam> create(const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
{
return adoptRef(new AudioParam(name, defaultValue, minValue, maxValue, units));
}
AudioParam(const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
: m_name(name)
, m_value(defaultValue)
, m_defaultValue(defaultValue)
, m_minValue(minValue)
, m_maxValue(maxValue)
, m_units(units)
, m_smoothedValue(defaultValue)
, m_smoothingConstant(DefaultSmoothingConstant)
{
}
float value() const { return static_cast<float>(m_value); }
void 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;
}
String name() const { return m_name; }
float minValue() const { return static_cast<float>(m_minValue); }
float maxValue() const { return static_cast<float>(m_maxValue); }
float defaultValue() const { return static_cast<float>(m_defaultValue); }
unsigned units() const { return m_units; }
// Value smoothing:
// When a new value is set with setValue(), in our internal use of the parameter we don't immediately jump to it.
// Instead we smoothly approach this value to avoid glitching.
float smoothedValue() const { return static_cast<float>(m_smoothedValue); }
// Smoothly exponentially approaches to (de-zippers) the desired value.
// Returns true if smoothed value has already snapped exactly to value.
bool 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;
}
void resetSmoothedValue() { m_smoothedValue = m_value; }
void setSmoothingConstant(double k) { m_smoothingConstant = k; }
private:
String m_name;
double m_value;
double m_defaultValue;
double m_minValue;
double m_maxValue;
unsigned m_units;
// Smoothing (de-zippering)
double m_smoothedValue;
double m_smoothingConstant;
};
} // namespace WebCore
#endif // AudioParam_h
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