JUCE/modules/juce_audio_formats/format/juce_AudioSubsectionReader.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.

   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
   27th April 2017).

   End User License Agreement: www.juce.com/juce-5-licence
   Privacy Policy: www.juce.com/juce-5-privacy-policy

   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).

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

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

namespace juce
{

//==============================================================================
/**
    This class is used to wrap an AudioFormatReader and only read from a
    subsection of the file.

    So if you have a reader which can read a 1000 sample file, you could wrap it
    in one of these to only access, e.g. samples 100 to 200, and any samples
    outside that will come back as 0. Accessing sample 0 from this reader will
    actually read the first sample from the other's subsection, which might
    be at a non-zero position.

    @see AudioFormatReader

    @tags{Audio}
*/
class JUCE_API  AudioSubsectionReader  : public AudioFormatReader
{
public:
    //==============================================================================
    /** Creates an AudioSubsectionReader for a given data source.

        @param sourceReader             the source reader from which we'll be taking data
        @param subsectionStartSample    the sample within the source reader which will be
                                        mapped onto sample 0 for this reader.
        @param subsectionLength         the number of samples from the source that will
                                        make up the subsection. If this reader is asked for
                                        any samples beyond this region, it will return zero.
        @param deleteSourceWhenDeleted  if true, the sourceReader object will be deleted when
                                        this object is deleted.
    */
    AudioSubsectionReader (AudioFormatReader* sourceReader,
                           int64 subsectionStartSample,
                           int64 subsectionLength,
                           bool deleteSourceWhenDeleted);

    /** Destructor. */
    ~AudioSubsectionReader() override;


    //==============================================================================
    bool readSamples (int** destSamples, int numDestChannels, int startOffsetInDestBuffer,
                      int64 startSampleInFile, int numSamples) override;

    void readMaxLevels (int64 startSample, int64 numSamples,
                        Range<float>* results, int numChannelsToRead) override;


private:
    //==============================================================================
    AudioFormatReader* const source;
    int64 startSample, length;
    const bool deleteSourceWhenDeleted;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioSubsectionReader)
};

} // namespace juce