juce_ImageCache.cpp

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 /*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - 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 7 End-User License
   Agreement and JUCE Privacy Policy.
 
   End User License Agreement: www.juce.com/juce-7-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
{
 
struct ImageCache::Pimpl     : private Timer,
                               private DeletedAtShutdown
{
    Pimpl() = default;
 
    ~Pimpl() override
    {
        stopTimer();
        clearSingletonInstance();
    }
 
    JUCE_DECLARE_SINGLETON (ImageCache::Pimpl, false)
 
    Image getFromHashCode (const int64 hashCode) noexcept
    {
        const ScopedLock sl (lock);
 
        for (auto& item : images)
        {
            if (item.hashCode == hashCode)
            {
                item.lastUseTime = Time::getApproximateMillisecondCounter();
                return item.image;
            }
        }
 
        return {};
     }
 
    void addImageToCache (const Image& image, const int64 hashCode)
    {
        if (image.isValid())
        {
            if (! isTimerRunning())
                startTimer (2000);
 
            const ScopedLock sl (lock);
            images.add ({ image, hashCode, Time::getApproximateMillisecondCounter() });
        }
    }
 
    void timerCallback() override
    {
        auto now = Time::getApproximateMillisecondCounter();
 
        const ScopedLock sl (lock);
 
        for (int i = images.size(); --i >= 0;)
        {
            auto& item = images.getReference (i);
 
            if (item.image.getReferenceCount() <= 1)
            {
                if (now > item.lastUseTime + cacheTimeout || now < item.lastUseTime - 1000)
                    images.remove (i);
            }
            else
            {
                item.lastUseTime = now; // multiply-referenced, so this image is still in use.
            }
        }
 
        if (images.isEmpty())
            stopTimer();
    }
 
    void releaseUnusedImages()
    {
        const ScopedLock sl (lock);
 
        for (int i = images.size(); --i >= 0;)
            if (images.getReference (i).image.getReferenceCount() <= 1)
                images.remove (i);
    }
 
    struct Item
    {
        Image image;
        int64 hashCode;
        uint32 lastUseTime;
    };
 
    Array<Item> images;
    CriticalSection lock;
    unsigned int cacheTimeout = 5000;
 
    JUCE_DECLARE_NON_COPYABLE (Pimpl)
};
 
JUCE_IMPLEMENT_SINGLETON (ImageCache::Pimpl)
 
 
//==============================================================================
Image ImageCache::getFromHashCode (const int64 hashCode)
{
    if (Pimpl::getInstanceWithoutCreating() != nullptr)
        return Pimpl::getInstanceWithoutCreating()->getFromHashCode (hashCode);
 
    return {};
}
 
void ImageCache::addImageToCache (const Image& image, const int64 hashCode)
{
    Pimpl::getInstance()->addImageToCache (image, hashCode);
}
 
Image ImageCache::getFromFile (const File& file)
{
    auto hashCode = file.hashCode64();
    auto image = getFromHashCode (hashCode);
 
    if (image.isNull())
    {
        image = ImageFileFormat::loadFrom (file);
        addImageToCache (image, hashCode);
    }
 
    return image;
}
 
Image ImageCache::getFromMemory (const void* imageData, const int dataSize)
{
    auto hashCode = (int64) (pointer_sized_int) imageData;
    auto image = getFromHashCode (hashCode);
 
    if (image.isNull())
    {
        image = ImageFileFormat::loadFrom (imageData, (size_t) dataSize);
        addImageToCache (image, hashCode);
    }
 
    return image;
}
 
void ImageCache::setCacheTimeout (const int millisecs)
{
    jassert (millisecs >= 0);
    Pimpl::getInstance()->cacheTimeout = (unsigned int) millisecs;
}
 
void ImageCache::releaseUnusedImages()
{
    Pimpl::getInstance()->releaseUnusedImages();
}
 
} // namespace juce