1/*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1.  Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 * 2.  Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 *     its contributors may be used to endorse or promote products derived
15 *     from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef AudioParam_h
30#define AudioParam_h
31
32#include "PlatformString.h"
33#include <sys/types.h>
34#include <wtf/PassRefPtr.h>
35#include <wtf/RefCounted.h>
36
37namespace WebCore {
38
39class AudioParam : public RefCounted<AudioParam> {
40public:
41    static const double DefaultSmoothingConstant;
42    static const double SnapThreshold;
43
44    static PassRefPtr<AudioParam> create(const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
45    {
46        return adoptRef(new AudioParam(name, defaultValue, minValue, maxValue, units));
47    }
48
49    AudioParam(const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
50        : m_name(name)
51        , m_value(defaultValue)
52        , m_defaultValue(defaultValue)
53        , m_minValue(minValue)
54        , m_maxValue(maxValue)
55        , m_units(units)
56        , m_smoothedValue(defaultValue)
57        , m_smoothingConstant(DefaultSmoothingConstant)
58    {
59    }
60
61    float value() const { return static_cast<float>(m_value); }
62
63    void setValue(float);
64
65    String name() const { return m_name; }
66
67    float minValue() const { return static_cast<float>(m_minValue); }
68    float maxValue() const { return static_cast<float>(m_maxValue); }
69    float defaultValue() const { return static_cast<float>(m_defaultValue); }
70    unsigned units() const { return m_units; }
71
72    // Value smoothing:
73
74    // When a new value is set with setValue(), in our internal use of the parameter we don't immediately jump to it.
75    // Instead we smoothly approach this value to avoid glitching.
76    float smoothedValue() const { return static_cast<float>(m_smoothedValue); }
77
78    // Smoothly exponentially approaches to (de-zippers) the desired value.
79    // Returns true if smoothed value has already snapped exactly to value.
80    bool smooth();
81
82    void resetSmoothedValue() { m_smoothedValue = m_value; }
83    void setSmoothingConstant(double k) { m_smoothingConstant = k; }
84
85private:
86    String m_name;
87    double m_value;
88    double m_defaultValue;
89    double m_minValue;
90    double m_maxValue;
91    unsigned m_units;
92
93    // Smoothing (de-zippering)
94    double m_smoothedValue;
95    double m_smoothingConstant;
96};
97
98} // namespace WebCore
99
100#endif // AudioParam_h
101