JUCE/modules/juce_core/streams/juce_SubregionStream.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2017 - ROLI Ltd.

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

SubregionStream::SubregionStream (InputStream* const sourceStream,
                                  const int64 start, const int64 length,
                                  const bool deleteSourceWhenDestroyed)
  : source (sourceStream, deleteSourceWhenDestroyed),
    startPositionInSourceStream (start),
    lengthOfSourceStream (length)
{
    SubregionStream::setPosition (0);
}

SubregionStream::~SubregionStream()
{
}

int64 SubregionStream::getTotalLength()
{
    const int64 srcLen = source->getTotalLength() - startPositionInSourceStream;

    return lengthOfSourceStream >= 0 ? jmin (lengthOfSourceStream, srcLen)
                                     : srcLen;
}

int64 SubregionStream::getPosition()
{
    return source->getPosition() - startPositionInSourceStream;
}

bool SubregionStream::setPosition (int64 newPosition)
{
    return source->setPosition (jmax ((int64) 0, newPosition + startPositionInSourceStream));
}

int SubregionStream::read (void* destBuffer, int maxBytesToRead)
{
    jassert (destBuffer != nullptr && maxBytesToRead >= 0);

    if (lengthOfSourceStream < 0)
        return source->read (destBuffer, maxBytesToRead);

    maxBytesToRead = (int) jmin ((int64) maxBytesToRead, lengthOfSourceStream - getPosition());

    if (maxBytesToRead <= 0)
        return 0;

    return source->read (destBuffer, maxBytesToRead);
}

bool SubregionStream::isExhausted()
{
    if (lengthOfSourceStream >= 0 && getPosition() >= lengthOfSourceStream)
        return true;

    return source->isExhausted();
}