paulxstretch/deps/juce/modules/juce_audio_utils/gui/juce_AudioThumbnailCache.h

119 lines
4.2 KiB
C
Raw Normal View History

/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2020 - Raw Material Software Limited
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 6 End-User License
Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).
End User License Agreement: www.juce.com/juce-6-licence
Privacy Policy: www.juce.com/juce-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
{
//==============================================================================
/**
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
@tags{Audio}
*/
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. */
virtual ~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);
/** Tells the cache to forget about the thumb with the given hashcode. */
void removeThumb (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; }
protected:
/** This can be overridden to provide a custom callback for saving thumbnails
once they have finished being loaded.
*/
virtual void saveNewlyFinishedThumbnail (const AudioThumbnailBase&, int64 hashCode);
/** This can be overridden to provide a custom callback for loading thumbnails
from pre-saved files to save the cache the trouble of having to create them.
*/
virtual bool loadNewThumb (AudioThumbnailBase&, int64 hashCode);
private:
//==============================================================================
TimeSliceThread thread;
class ThumbnailCacheEntry;
OwnedArray<ThumbnailCacheEntry> thumbs;
CriticalSection lock;
int maxNumThumbsToStore;
ThumbnailCacheEntry* findThumbFor (int64 hash) const;
int findOldestThumb() const;
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioThumbnailCache)
};
} // namespace juce