AudioParamTimeline.h   [plain text]

/*
 * Copyright (C) 2011 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 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
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 */

#pragma once

#include "AudioContext.h"
#include <JavaScriptCore/Float32Array.h>
#include <wtf/Lock.h>
#include <wtf/Vector.h>

namespace WebCore {

class AudioParamTimeline {
    WTF_MAKE_NONCOPYABLE(AudioParamTimeline);
    WTF_MAKE_FAST_ALLOCATED;
public:
    AudioParamTimeline()
    {
    }

    ExceptionOr<void> setValueAtTime(float value, Seconds time);
    ExceptionOr<void> linearRampToValueAtTime(float value, Seconds time);
    ExceptionOr<void> exponentialRampToValueAtTime(float value, Seconds time);
    ExceptionOr<void> setTargetAtTime(float target, Seconds time, float timeConstant);
    ExceptionOr<void> setValueCurveAtTime(Vector<float>&& curve, Seconds time, Seconds duration);
    void cancelScheduledValues(Seconds startTime);

    // hasValue is set to true if a valid timeline value is returned.
    // otherwise defaultValue is returned.
    float valueForContextTime(BaseAudioContext&, float defaultValue, bool& hasValue);

    // Given the time range, calculates parameter values into the values buffer
    // and returns the last parameter value calculated for "values" or the defaultValue if none were calculated.
    // controlRate is the rate (number per second) at which parameter values will be calculated.
    // It should equal sampleRate for sample-accurate parameter changes, and otherwise will usually match
    // the render quantum size such that the parameter value changes once per render quantum.
    float valuesForTimeRange(Seconds startTime, Seconds endTime, float defaultValue, float* values, unsigned numberOfValues, double sampleRate, double controlRate);

    bool hasValues() { return m_events.size(); }

private:
    class ParamEvent {
    public:
        enum Type {
            SetValue,
            LinearRampToValue,
            ExponentialRampToValue,
            SetTarget,
            SetValueCurve,
            LastType
        };

        ParamEvent(Type type, float value, Seconds time, float timeConstant, Seconds duration, Vector<float>&& curve)
            : m_type(type)
            , m_value(value)
            , m_time(time)
            , m_timeConstant(timeConstant)
            , m_duration(duration)
            , m_curve(WTFMove(curve))
        {
        }

        unsigned type() const { return m_type; }
        float value() const { return m_value; }
        Seconds time() const { return m_time; }
        float timeConstant() const { return m_timeConstant; }
        Seconds duration() const { return m_duration; }
        Vector<float>& curve() { return m_curve; }

    private:
        unsigned m_type;
        float m_value;
        Seconds m_time;
        float m_timeConstant;
        Seconds m_duration;
        Vector<float> m_curve;
    };

    ExceptionOr<void> insertEvent(const ParamEvent&);
    float valuesForTimeRangeImpl(Seconds startTime, Seconds endTime, float defaultValue, float* values, unsigned numberOfValues, double sampleRate, double controlRate);

    Vector<ParamEvent> m_events;

    Lock m_eventsMutex;
};

} // namespace WebCore