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      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
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     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 "bindings/v8/ScriptWrappable.h"
     33 #include "modules/webaudio/AudioContext.h"
     34 #include "modules/webaudio/AudioParamTimeline.h"
     35 #include "modules/webaudio/AudioSummingJunction.h"
     36 #include <sys/types.h>
     37 #include "wtf/Float32Array.h"
     38 #include "wtf/PassRefPtr.h"
     39 #include "wtf/RefCounted.h"
     40 #include "wtf/text/WTFString.h"
     41 
     42 namespace WebCore {
     43 
     44 class AudioNodeOutput;
     45 
     46 class AudioParam : public RefCounted<AudioParam>, public ScriptWrappable, public AudioSummingJunction {
     47 public:
     48     static const double DefaultSmoothingConstant;
     49     static const double SnapThreshold;
     50 
     51     static PassRefPtr<AudioParam> create(AudioContext* context, const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
     52     {
     53         return adoptRef(new AudioParam(context, name, defaultValue, minValue, maxValue, units));
     54     }
     55 
     56     // AudioSummingJunction
     57     virtual bool canUpdateState() OVERRIDE { return true; }
     58     virtual void didUpdate() OVERRIDE { }
     59 
     60     // Intrinsic value.
     61     float value();
     62     void setValue(float);
     63 
     64     // Final value for k-rate parameters, otherwise use calculateSampleAccurateValues() for a-rate.
     65     // Must be called in the audio thread.
     66     float finalValue();
     67 
     68     String name() const { return m_name; }
     69 
     70     float minValue() const { return static_cast<float>(m_minValue); }
     71     float maxValue() const { return static_cast<float>(m_maxValue); }
     72     float defaultValue() const { return static_cast<float>(m_defaultValue); }
     73     unsigned units() const { return m_units; }
     74 
     75     // Value smoothing:
     76 
     77     // When a new value is set with setValue(), in our internal use of the parameter we don't immediately jump to it.
     78     // Instead we smoothly approach this value to avoid glitching.
     79     float smoothedValue();
     80 
     81     // Smoothly exponentially approaches to (de-zippers) the desired value.
     82     // Returns true if smoothed value has already snapped exactly to value.
     83     bool smooth();
     84 
     85     void resetSmoothedValue() { m_smoothedValue = m_value; }
     86     void setSmoothingConstant(double k) { m_smoothingConstant = k; }
     87 
     88     // Parameter automation.
     89     void setValueAtTime(float value, double time) { m_timeline.setValueAtTime(value, time); }
     90     void linearRampToValueAtTime(float value, double time) { m_timeline.linearRampToValueAtTime(value, time); }
     91     void exponentialRampToValueAtTime(float value, double time) { m_timeline.exponentialRampToValueAtTime(value, time); }
     92     void setTargetAtTime(float target, double time, double timeConstant) { m_timeline.setTargetAtTime(target, time, timeConstant); }
     93     void setValueCurveAtTime(Float32Array* curve, double time, double duration) { m_timeline.setValueCurveAtTime(curve, time, duration); }
     94     void cancelScheduledValues(double startTime) { m_timeline.cancelScheduledValues(startTime); }
     95 
     96     bool hasSampleAccurateValues() { return m_timeline.hasValues() || numberOfRenderingConnections(); }
     97 
     98     // Calculates numberOfValues parameter values starting at the context's current time.
     99     // Must be called in the context's render thread.
    100     void calculateSampleAccurateValues(float* values, unsigned numberOfValues);
    101 
    102     // Connect an audio-rate signal to control this parameter.
    103     void connect(AudioNodeOutput*);
    104     void disconnect(AudioNodeOutput*);
    105 
    106 protected:
    107     AudioParam(AudioContext* context, const String& name, double defaultValue, double minValue, double maxValue, unsigned units = 0)
    108         : AudioSummingJunction(context)
    109         , m_name(name)
    110         , m_value(defaultValue)
    111         , m_defaultValue(defaultValue)
    112         , m_minValue(minValue)
    113         , m_maxValue(maxValue)
    114         , m_units(units)
    115         , m_smoothedValue(defaultValue)
    116         , m_smoothingConstant(DefaultSmoothingConstant)
    117     {
    118         ScriptWrappable::init(this);
    119     }
    120 
    121 private:
    122     // sampleAccurate corresponds to a-rate (audio rate) vs. k-rate in the Web Audio specification.
    123     void calculateFinalValues(float* values, unsigned numberOfValues, bool sampleAccurate);
    124     void calculateTimelineValues(float* values, unsigned numberOfValues);
    125 
    126     String m_name;
    127     double m_value;
    128     double m_defaultValue;
    129     double m_minValue;
    130     double m_maxValue;
    131     unsigned m_units;
    132 
    133     // Smoothing (de-zippering)
    134     double m_smoothedValue;
    135     double m_smoothingConstant;
    136 
    137     AudioParamTimeline m_timeline;
    138 };
    139 
    140 } // namespace WebCore
    141 
    142 #endif // AudioParam_h
    143