File indexing completed on 2024-09-15 04:23:06

 /*
     SPDX-FileCopyrightText: 2017 Nicolas Carion
     SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
 */
 
 #pragma once
 
 #include "definitions.h"
 #include <QDir>
 #include <QImage>
 #include <QMutex>
 #include <QUrl>
 #include <memory>
 #include <mutex>
 #include <unordered_map>
 #include <vector>
 
 /** @class ThumbnailCache
     @brief This class class is an interface to the caches that store thumbnails.
     In Kdenlive, we use two such caches, a persistent that is stored on disk to allow thumbnails to be reused when reopening.
     The other one is a volatile LRU cache that lives in memory.
     Note that for the volatile cache uses a custom implementation.
     QCache is not suitable since it operates on pointers and since the object is removed from the cache when accessed.
     KImageCache is not suitable since it lacks a way to remove objects from the cache.
  * Note that this class is a Singleton
  */
 class ThumbnailCache
 {
 
 public:
     // Returns the instance of the Singleton
     static std::unique_ptr<ThumbnailCache> &get();
 
     /** @brief Check whether a given thumbnail is in the cache
        @param binId is the id of the queried clip
        @param pos is the position where we query
        @param volatileOnly if true, we only check the volatile cache (no disk access)
      */
     bool hasThumbnail(const QString &binId, int pos, bool volatileOnly = false) const;
 
     /** @brief Get a given thumbnail from the cache
        @param binId is the id of the queried clip
        @param pos is the position where we query
        @param volatileOnly if true, we only check the volatile cache (no disk access)
     */
     QImage getThumbnail(QString hash, const QString &binId, int pos, bool volatileOnly = false) const;
     QImage getThumbnail(const QString &binId, int pos, bool volatileOnly = false) const;
     QImage getAudioThumbnail(const QString &binId, bool volatileOnly = false) const;
     const QList<QUrl> getAudioThumbPath(const QString &binId) const;
 
     /** @brief Get a given thumbnail from the cache
        @param binId is the id of the queried clip
        @param pos is the position where we query
        @param persistent if true, we store the image in the persistent cache, which generates a disk access
     */
     void storeThumbnail(const QString &binId, int pos, const QImage &img, bool persistent = false);
 
     /** @brief Removes all the thumbnails for a given clip */
     void invalidateThumbsForClip(const QString &binId);
 
     /** @brief Save all cached thumbs to disk */
     void saveCachedThumbs(const std::unordered_map<QString, std::vector<int>> &keys);
 
     /** @brief Reset cache (discarding all thumbs stored in memory) */
     void clearCache();
 
     /** @brief Ensure the cache is not corrupted */
     bool checkIntegrity() const;
 
 protected:
     // Constructor is protected because class is a Singleton
     ThumbnailCache();
 
     // Return the key associated to a thumbnail
     static QString getKey(const QString &binId, int pos, bool *ok);
     static QStringList getAudioKey(const QString &binId, bool *ok);
 
     // Return the dir where the persistent cache lives
     static const QDir getDir(bool audio, bool *ok);
 
     static std::unique_ptr<ThumbnailCache> instance;
     static std::once_flag m_onceFlag; // flag to create the repository only once;
 
     class Cache_t;
     std::unique_ptr<Cache_t> m_volatileCache;
     mutable QMutex m_mutex;
 
     // the following maps keeps track of the positions that we store for each clip in volatile caches.
     // Note that we don't track deletions due to items dropped from the cache. So the maps can contain more items that are currently stored.
     std::unordered_map<QString, std::vector<int>> m_storedVolatile;
     mutable std::unordered_map<QString, std::vector<int>> m_storedOnDisk;
 };