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

   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 #include "../../core/juce_StandardHeader.h"
  27
  28 BEGIN_JUCE_NAMESPACE
  29
  30 #include "juce_AudioThumbnailCache.h"
  31 #include "../../io/streams/juce_MemoryInputStream.h"
  32 #include "../../io/streams/juce_MemoryOutputStream.h"
  33
  34
  35 //==============================================================================
  36 struct ThumbnailCacheEntry
  37 {
  38     int64 hash;
  39     uint32 lastUsed;
  40     MemoryBlock data;
  41
  42     JUCE_LEAK_DETECTOR (ThumbnailCacheEntry);
  43 };
  44
  45 //==============================================================================
  46 AudioThumbnailCache::AudioThumbnailCache (const int maxNumThumbsToStore_)
  47     : TimeSliceThread ("thumb cache"),
  48       maxNumThumbsToStore (maxNumThumbsToStore_)
  49 {
  50     startThread (2);
  51 }
  52
  53 AudioThumbnailCache::~AudioThumbnailCache()
  54 {
  55 }
  56
  57 ThumbnailCacheEntry* AudioThumbnailCache::findThumbFor (const int64 hash) const
  58 {
  59     for (int i = thumbs.size(); --i >= 0;)
  60         if (thumbs.getUnchecked(i)->hash == hash)
  61             return thumbs.getUnchecked(i);
  62
  63     return nullptr;
  64 }
  65
  66 bool AudioThumbnailCache::loadThumb (AudioThumbnail& thumb, const int64 hashCode)
  67 {
  68     ThumbnailCacheEntry* te = findThumbFor (hashCode);
  69
  70     if (te != nullptr)
  71     {
  72         te->lastUsed = Time::getMillisecondCounter();
  73
  74         MemoryInputStream in (te->data, false);
  75         thumb.loadFrom (in);
  76         return true;
  77     }
  78
  79     return false;
  80 }
  81
  82 void AudioThumbnailCache::storeThumb (const AudioThumbnail& thumb,
  83                                       const int64 hashCode)
  84 {
  85     ThumbnailCacheEntry* te = findThumbFor (hashCode);
  86
  87     if (te == nullptr)
  88     {
  89         te = new ThumbnailCacheEntry();
  90         te->hash = hashCode;
  91
  92         if (thumbs.size() < maxNumThumbsToStore)
  93         {
  94             thumbs.add (te);
  95         }
  96         else
  97         {
  98             int oldest = 0;
  99             uint32 oldestTime = Time::getMillisecondCounter() + 1;
 100
 101             for (int i = thumbs.size(); --i >= 0;)
 102             {
 103                 if (thumbs.getUnchecked(i)->lastUsed < oldestTime)
 104                 {
 105                     oldest = i;
 106                     oldestTime = thumbs.getUnchecked(i)->lastUsed;
 107                 }
 108             }
 109
 110             thumbs.set (oldest, te);
 111         }
 112     }
 113
 114     te->lastUsed = Time::getMillisecondCounter();
 115
 116     MemoryOutputStream out (te->data, false);
 117     thumb.saveTo (out);
 118 }
 119
 120 void AudioThumbnailCache::clear()
 121 {
 122     thumbs.clear();
 123 }
 124
 125
 126 END_JUCE_NAMESPACE