120 lines
4.2 KiB
C++
120 lines
4.2 KiB
C++
/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2017 - ROLI Ltd.
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JUCE is an open source library subject to commercial or open-source
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licensing.
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By using JUCE, you agree to the terms of both the JUCE 5 End-User License
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Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
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27th April 2017).
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End User License Agreement: www.juce.com/juce-5-licence
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Privacy Policy: www.juce.com/juce-5-privacy-policy
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Or: You may also use this code under the terms of the GPL v3 (see
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www.gnu.org/licenses).
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JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
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EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
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DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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//==============================================================================
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/**
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An instance of this class is used to manage multiple AudioThumbnail objects.
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The cache runs a single background thread that is shared by all the thumbnails
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that need it, and it maintains a set of low-res previews in memory, to avoid
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having to re-scan audio files too often.
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@see AudioThumbnail
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@tags{Audio}
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*/
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class JUCE_API AudioThumbnailCache
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{
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public:
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//==============================================================================
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/** Creates a cache object.
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The maxNumThumbsToStore parameter lets you specify how many previews should
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be kept in memory at once.
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*/
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explicit AudioThumbnailCache (int maxNumThumbsToStore);
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/** Destructor. */
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virtual ~AudioThumbnailCache();
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//==============================================================================
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/** Clears out any stored thumbnails. */
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void clear();
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/** Reloads the specified thumb if this cache contains the appropriate stored
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data.
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This is called automatically by the AudioThumbnail class, so you shouldn't
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normally need to call it directly.
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*/
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bool loadThumb (AudioThumbnailBase& thumb, int64 hashCode);
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/** Stores the cachable data from the specified thumb in this cache.
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This is called automatically by the AudioThumbnail class, so you shouldn't
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normally need to call it directly.
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*/
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void storeThumb (const AudioThumbnailBase& thumb, int64 hashCode);
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/** Tells the cache to forget about the thumb with the given hashcode. */
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void removeThumb (int64 hashCode);
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//==============================================================================
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/** Attempts to re-load a saved cache of thumbnails from a stream.
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The cache data must have been written by the writeToStream() method.
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This will replace all currently-loaded thumbnails with the new data.
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*/
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bool readFromStream (InputStream& source);
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/** Writes all currently-loaded cache data to a stream.
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The resulting data can be re-loaded with readFromStream().
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*/
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void writeToStream (OutputStream& stream);
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/** Returns the thread that client thumbnails can use. */
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TimeSliceThread& getTimeSliceThread() noexcept { return thread; }
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protected:
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/** This can be overridden to provide a custom callback for saving thumbnails
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once they have finished being loaded.
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*/
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virtual void saveNewlyFinishedThumbnail (const AudioThumbnailBase&, int64 hashCode);
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/** This can be overridden to provide a custom callback for loading thumbnails
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from pre-saved files to save the cache the trouble of having to create them.
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*/
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virtual bool loadNewThumb (AudioThumbnailBase&, int64 hashCode);
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private:
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//==============================================================================
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TimeSliceThread thread;
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class ThumbnailCacheEntry;
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OwnedArray<ThumbnailCacheEntry> thumbs;
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CriticalSection lock;
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int maxNumThumbsToStore;
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ThumbnailCacheEntry* findThumbFor (int64 hash) const;
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int findOldestThumb() const;
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JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioThumbnailCache)
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};
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} // namespace juce
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