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JUCE/modules/juce_audio_utils/gui/juce_AudioThumbnailCache.h

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/*
==============================================================================
This file is part of the JUCE library - "Jules' Utility Class Extensions"
Copyright 2004-11 by Raw Material Software Ltd.
------------------------------------------------------------------------------
JUCE can be redistributed and/or modified under the terms of the GNU General
Public License (Version 2), as published by the Free Software Foundation.
A copy of the license is included in the JUCE distribution, or can be found
online at www.gnu.org/licenses.
JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
------------------------------------------------------------------------------
To release a closed-source product which uses JUCE, commercial licenses are
available: visit www.rawmaterialsoftware.com/juce for more information.
==============================================================================
*/
#ifndef __JUCE_AUDIOTHUMBNAILCACHE_JUCEHEADER__
#define __JUCE_AUDIOTHUMBNAILCACHE_JUCEHEADER__
#include "juce_AudioThumbnailBase.h"
//==============================================================================
/**
An instance of this class is used to manage multiple AudioThumbnail objects.
The cache runs a single background thread that is shared by all the thumbnails
that need it, and it maintains a set of low-res previews in memory, to avoid
having to re-scan audio files too often.
@see AudioThumbnail
*/
class JUCE_API AudioThumbnailCache
{
public:
//==============================================================================
/** Creates a cache object.
The maxNumThumbsToStore parameter lets you specify how many previews should
be kept in memory at once.
*/
explicit AudioThumbnailCache (int maxNumThumbsToStore);
/** Destructor. */
~AudioThumbnailCache();
//==============================================================================
/** Clears out any stored thumbnails.
*/
void clear();
/** Reloads the specified thumb if this cache contains the appropriate stored
data.
This is called automatically by the AudioThumbnail class, so you shouldn't
normally need to call it directly.
*/
bool loadThumb (AudioThumbnailBase& thumb, int64 hashCode);
/** Stores the cachable data from the specified thumb in this cache.
This is called automatically by the AudioThumbnail class, so you shouldn't
normally need to call it directly.
*/
void storeThumb (const AudioThumbnailBase& thumb, int64 hashCode);
//==============================================================================
/** Attempts to re-load a saved cache of thumbnails from a stream.
The cache data must have been written by the writeToStream() method.
This will replace all currently-loaded thumbnails with the new data.
*/
bool readFromStream (InputStream& source);
/** Writes all currently-loaded cache data to a stream.
The resulting data can be re-loaded with readFromStream().
*/
void writeToStream (OutputStream& stream);
/** Returns the thread that client thumbnails can use. */
TimeSliceThread& getTimeSliceThread() noexcept { return thread; }
private:
//==============================================================================
TimeSliceThread thread;
class ThumbnailCacheEntry;
friend class OwnedArray<ThumbnailCacheEntry>;
OwnedArray<ThumbnailCacheEntry> thumbs;
CriticalSection lock;
int maxNumThumbsToStore;
ThumbnailCacheEntry* findThumbFor (int64 hash) const;
int findOldestThumb() const;
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioThumbnailCache);
};
#endif // __JUCE_AUDIOTHUMBNAILCACHE_JUCEHEADER__