juce/source/src/audio/audio_file_formats/juce_AudioThumbnailCache.h

   1 /*
   2   ==============================================================================
   3
   4    This file is part of the JUCE library - "Jules' Utility Class Extensions"
   5    Copyright 2004-11 by Raw Material Software Ltd.
   6
   7   ------------------------------------------------------------------------------
   8
   9    JUCE can be redistributed and/or modified under the terms of the GNU General
  10    Public License (Version 2), as published by the Free Software Foundation.
  11    A copy of the license is included in the JUCE distribution, or can be found
  12    online at www.gnu.org/licenses.
  13
  14    JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
  15    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  16    A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  17
  18   ------------------------------------------------------------------------------
  19
  20    To release a closed-source product which uses JUCE, commercial licenses are
  21    available: visit www.rawmaterialsoftware.com/juce for more information.
  22
  23   ==============================================================================
  24 */
  25
  26 #ifndef __JUCE_AUDIOTHUMBNAILCACHE_JUCEHEADER__
  27 #define __JUCE_AUDIOTHUMBNAILCACHE_JUCEHEADER__
  28
  29 #include "juce_AudioThumbnail.h"
  30 struct ThumbnailCacheEntry;
  31
  32
  33 //==============================================================================
  34 /**
  35     An instance of this class is used to manage multiple AudioThumbnail objects.
  36
  37     The cache runs a single background thread that is shared by all the thumbnails
  38     that need it, and it maintains a set of low-res previews in memory, to avoid
  39     having to re-scan audio files too often.
  40
  41     @see AudioThumbnail
  42 */
  43 class JUCE_API  AudioThumbnailCache   : public TimeSliceThread
  44 {
  45 public:
  46     //==============================================================================
  47     /** Creates a cache object.
  48
  49         The maxNumThumbsToStore parameter lets you specify how many previews should
  50         be kept in memory at once.
  51     */
  52     explicit AudioThumbnailCache (int maxNumThumbsToStore);
  53
  54     /** Destructor. */
  55     ~AudioThumbnailCache();
  56
  57     //==============================================================================
  58     /** Clears out any stored thumbnails.
  59     */
  60     void clear();
  61
  62     /** Reloads the specified thumb if this cache contains the appropriate stored
  63         data.
  64
  65         This is called automatically by the AudioThumbnail class, so you shouldn't
  66         normally need to call it directly.
  67     */
  68     bool loadThumb (AudioThumbnail& thumb, int64 hashCode);
  69
  70     /** Stores the cachable data from the specified thumb in this cache.
  71
  72         This is called automatically by the AudioThumbnail class, so you shouldn't
  73         normally need to call it directly.
  74     */
  75     void storeThumb (const AudioThumbnail& thumb, int64 hashCode);
  76
  77
  78 private:
  79     //==============================================================================
  80     OwnedArray <ThumbnailCacheEntry> thumbs;
  81     int maxNumThumbsToStore;
  82
  83     ThumbnailCacheEntry* findThumbFor (int64 hash) const;
  84
  85     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioThumbnailCache);
  86 };
  87
  88
  89 #endif   // __JUCE_AUDIOTHUMBNAILCACHE_JUCEHEADER__