root/Source/modules/webaudio/AudioBasicInspectorNode.cpp

DEFINITIONS

1. m_needAutomaticPull
2. pullInputs
3. connect
4. disconnect
5. checkNumberOfChannelsForInput
6. updatePullStatus

/*
 * Copyright (C) 2012, Intel Corporation. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. 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 INC. 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
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "modules/webaudio/AudioBasicInspectorNode.h"

#include "modules/webaudio/AudioContext.h"
#include "modules/webaudio/AudioNodeInput.h"
#include "modules/webaudio/AudioNodeOutput.h"

namespace WebCore {

AudioBasicInspectorNode::AudioBasicInspectorNode(AudioContext* context, float sampleRate, unsigned outputChannelCount)
    : AudioNode(context, sampleRate)
    , m_needAutomaticPull(false)
{
    addInput(adoptPtr(new AudioNodeInput(this)));
    addOutput(adoptPtr(new AudioNodeOutput(this, outputChannelCount)));
}

// We override pullInputs() as an optimization allowing this node to take advantage of in-place processing,
// where the input is simply passed through unprocessed to the output.
// Note: this only applies if the input and output channel counts match.
void AudioBasicInspectorNode::pullInputs(size_t framesToProcess)
{
    // Render input stream - try to render directly into output bus for pass-through processing where process() doesn't need to do anything...
    input(0)->pull(output(0)->bus(), framesToProcess);
}

void AudioBasicInspectorNode::connect(AudioNode* destination, unsigned outputIndex, unsigned inputIndex, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    AudioContext::AutoLocker locker(context());

    AudioNode::connect(destination, outputIndex, inputIndex, exceptionState);
    updatePullStatus();
}

void AudioBasicInspectorNode::disconnect(unsigned outputIndex, ExceptionState& exceptionState)
{
    ASSERT(isMainThread());

    AudioContext::AutoLocker locker(context());

    AudioNode::disconnect(outputIndex, exceptionState);
    updatePullStatus();
}

void AudioBasicInspectorNode::checkNumberOfChannelsForInput(AudioNodeInput* input)
{
    ASSERT(context()->isAudioThread() && context()->isGraphOwner());

    ASSERT(input == this->input(0));
    if (input != this->input(0))
        return;

    unsigned numberOfChannels = input->numberOfChannels();

    if (numberOfChannels != output(0)->numberOfChannels()) {
        // This will propagate the channel count to any nodes connected further downstream in the graph.
        output(0)->setNumberOfChannels(numberOfChannels);
    }

    AudioNode::checkNumberOfChannelsForInput(input);

    updatePullStatus();
}

void AudioBasicInspectorNode::updatePullStatus()
{
    ASSERT(context()->isGraphOwner());

    if (output(0)->isConnected()) {
        // When an AudioBasicInspectorNode is connected to a downstream node, it will get pulled by the
        // downstream node, thus remove it from the context's automatic pull list.
        if (m_needAutomaticPull) {
            context()->removeAutomaticPullNode(this);
            m_needAutomaticPull = false;
        }
    } else {
        unsigned numberOfInputConnections = input(0)->numberOfRenderingConnections();
        if (numberOfInputConnections && !m_needAutomaticPull) {
            // When an AudioBasicInspectorNode is not connected to any downstream node while still connected from
            // upstream node(s), add it to the context's automatic pull list.
            context()->addAutomaticPullNode(this);
            m_needAutomaticPull = true;
        } else if (!numberOfInputConnections && m_needAutomaticPull) {
            // The AudioBasicInspectorNode is connected to nothing, remove it from the context's automatic pull list.
            context()->removeAutomaticPullNode(this);
            m_needAutomaticPull = false;
        }
    }
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)