JUCE/modules/juce_core/streams/juce_SubregionStream.h

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

   This file is part of the JUCE library.
   Copyright (c) 2016 - ROLI Ltd.

   Permission is granted to use this software 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.

   THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
   OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   OF THIS SOFTWARE.

   -----------------------------------------------------------------------------

   To release a closed-source product which uses other parts of JUCE not
   licensed under the ISC terms, commercial licenses are available: visit
   www.juce.com for more information.

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

#pragma once


//==============================================================================
/** Wraps another input stream, and reads from a specific part of it.

    This lets you take a subsection of a stream and present it as an entire
    stream in its own right.
*/
class JUCE_API  SubregionStream  : public InputStream
{
public:
    //==============================================================================
    /** Creates a SubregionStream from an input source.

        @param sourceStream                 the source stream to read from
        @param startPositionInSourceStream  this is the position in the source stream that
                                            corresponds to position 0 in this stream
        @param lengthOfSourceStream         this specifies the maximum number of bytes
                                            from the source stream that will be passed through
                                            by this stream. When the position of this stream
                                            exceeds lengthOfSourceStream, it will cause an end-of-stream.
                                            If the length passed in here is greater than the length
                                            of the source stream (as returned by getTotalLength()),
                                            then the smaller value will be used.
                                            Passing a negative value for this parameter means it
                                            will keep reading until the source's end-of-stream.
        @param deleteSourceWhenDestroyed    whether the sourceStream that is passed in should be
                                            deleted by this object when it is itself deleted.
    */
    SubregionStream (InputStream* sourceStream,
                     int64 startPositionInSourceStream,
                     int64 lengthOfSourceStream,
                     bool deleteSourceWhenDestroyed);

    /** Destructor.

        This may also delete the source stream, if that option was chosen when the
        buffered stream was created.
    */
    ~SubregionStream();


    //==============================================================================
    int64 getTotalLength() override;
    int64 getPosition() override;
    bool setPosition (int64 newPosition) override;
    int read (void* destBuffer, int maxBytesToRead) override;
    bool isExhausted() override;

private:
    //==============================================================================
    OptionalScopedPointer<InputStream> source;
    const int64 startPositionInSourceStream, lengthOfSourceStream;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (SubregionStream)
};