JUCE/modules/juce_audio_utils/gui/juce_AudioThumbnailCache.cpp

/*
  ==============================================================================

   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.

  ==============================================================================
*/

BEGIN_JUCE_NAMESPACE

//==============================================================================
struct ThumbnailCacheEntry
{
    int64 hash;
    uint32 lastUsed;
    MemoryBlock data;

    JUCE_LEAK_DETECTOR (ThumbnailCacheEntry);
};

//==============================================================================
AudioThumbnailCache::AudioThumbnailCache (const int maxNumThumbsToStore_)
    : TimeSliceThread ("thumb cache"),
      maxNumThumbsToStore (maxNumThumbsToStore_)
{
    startThread (2);
}

AudioThumbnailCache::~AudioThumbnailCache()
{
}

ThumbnailCacheEntry* AudioThumbnailCache::findThumbFor (const int64 hash) const
{
    for (int i = thumbs.size(); --i >= 0;)
        if (thumbs.getUnchecked(i)->hash == hash)
            return thumbs.getUnchecked(i);

    return nullptr;
}

bool AudioThumbnailCache::loadThumb (AudioThumbnail& thumb, const int64 hashCode)
{
    ThumbnailCacheEntry* te = findThumbFor (hashCode);

    if (te != nullptr)
    {
        te->lastUsed = Time::getMillisecondCounter();

        MemoryInputStream in (te->data, false);
        thumb.loadFrom (in);
        return true;
    }

    return false;
}

void AudioThumbnailCache::storeThumb (const AudioThumbnail& thumb,
                                      const int64 hashCode)
{
    ThumbnailCacheEntry* te = findThumbFor (hashCode);

    if (te == nullptr)
    {
        te = new ThumbnailCacheEntry();
        te->hash = hashCode;

        if (thumbs.size() < maxNumThumbsToStore)
        {
            thumbs.add (te);
        }
        else
        {
            int oldest = 0;
            uint32 oldestTime = Time::getMillisecondCounter() + 1;

            for (int i = thumbs.size(); --i >= 0;)
            {
                if (thumbs.getUnchecked(i)->lastUsed < oldestTime)
                {
                    oldest = i;
                    oldestTime = thumbs.getUnchecked(i)->lastUsed;
                }
            }

            thumbs.set (oldest, te);
        }
    }

    te->lastUsed = Time::getMillisecondCounter();

    MemoryOutputStream out (te->data, false);
    thumb.saveTo (out);
}

void AudioThumbnailCache::clear()
{
    thumbs.clear();
}


END_JUCE_NAMESPACE