JUCE/modules/juce_core/streams/juce_SubregionStream.h

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

   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.

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

#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)
};