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 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
18 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
21 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #include "config.h"
27
28 #if ENABLE(WEB_AUDIO)
29
30 #include "AudioParam.h"
31
32 #include <wtf/MathExtras.h>
33
34 namespace WebCore {
35
36 const double AudioParam::DefaultSmoothingConstant = 0.05;
37 const double AudioParam::SnapThreshold = 0.001;
38
setValue(float value)39 void AudioParam::setValue(float value)
40 {
41 // Check against JavaScript giving us bogus floating-point values.
42 // Don't ASSERT, since this can happen if somebody writes bad JS.
43 if (!isnan(value) && !isinf(value))
44 m_value = value;
45 }
46
smooth()47 bool AudioParam::smooth()
48 {
49 if (m_smoothedValue == m_value) {
50 // Smoothed value has already approached and snapped to value.
51 return true;
52 }
53
54 // Exponential approach
55 m_smoothedValue += (m_value - m_smoothedValue) * m_smoothingConstant;
56
57 // If we get close enough then snap to actual value.
58 if (fabs(m_smoothedValue - m_value) < SnapThreshold) // FIXME: the threshold needs to be adjustable depending on range - but this is OK general purpose value.
59 m_smoothedValue = m_value;
60
61 return false;
62 }
63
64 } // namespace WebCore
65
66 #endif // ENABLE(WEB_AUDIO)
67