File indexing completed on 2024-05-12 15:54:49

 /*
  * SPDX-FileCopyrightText: 2021 Arjen Hiemstra <ahiemstra@heimr.nl>
  *
  * SPDX-License-Identifier: LGPL-2.0-or-later
  */
 
 #include "fileinfo.h"
 
 #include <optional>
 
 #include <QGlobalStatic>
 #include <QImageReader>
 #include <QMetaObject>
 #include <QMimeDatabase>
 #include <QRunnable>
 #include <QThreadPool>
 
 struct FileInfoCacheEntry {
     QUrl source;
     QString mimeType;
     FileInfo::Type type = FileInfo::UnknownType;
     int width = -1;
     int height = -1;
 };
 
 /**
  * To make FileInfo objects cheap to use from QML, we cache the information it
  * uses in a separate structure. This allows FileInfo to quickly lookup and
  * retrieve information if we have already analyzed a file before. If not, we
  * use a background job to retrieve the actual information so we do not block
  * any other thread with potentially expensive file operations.
  */
 class FileInfoCache : public QObject
 {
     Q_OBJECT
 public:
     FileInfoCache();
 
     std::shared_ptr<FileInfoCacheEntry> get(const QUrl &url);
 
     void read(const QUrl &url);
     void readingFinished(const QUrl &url, std::shared_ptr<FileInfoCacheEntry> entry);
 
     Q_SIGNAL void cacheUpdated(const QUrl &url);
 
     QThreadPool threadPool;
     QHash<QUrl, std::shared_ptr<FileInfoCacheEntry>> cache;
 };
 
 Q_GLOBAL_STATIC(FileInfoCache, cache);
 
 class FileInfoRunnable : public QRunnable
 {
 public:
     QUrl source;
 
     void run() override
     {
         auto entry = std::make_shared<FileInfoCacheEntry>();
         entry->source = source;
 
         QMimeDatabase db;
         auto mimeType = db.mimeTypeForFile(source.toLocalFile(), QMimeDatabase::MatchContent);
 
         if (!mimeType.isValid()) {
             // Mime type is not valid, so either the source does not exist or we
             // don't have permission to read it. In any case, we cannot retrieve
             // information for this file, so abort.
 
             // Make a local copy of the source variable so we don't need to
             // capture "this" which will be destroyed after it completes.
             auto s = source;
 
             QMetaObject::invokeMethod(
                 cache(),
                 [s]() {
                     cache()->readingFinished(s, nullptr);
                 },
                 Qt::QueuedConnection);
             return;
         }
 
         auto mimeTypeName = mimeType.name();
         entry->mimeType = mimeTypeName;
 
         if (mimeTypeName.startsWith(QStringLiteral("video/")) || //
             mimeTypeName == QStringLiteral("application/x-matroska")) {
             entry->type = FileInfo::VideoType;
         } else if (mimeTypeName.startsWith(QStringLiteral("image/svg"))) {
             entry->type = FileInfo::VectorImageType;
         } else if (mimeTypeName == QStringLiteral("image/gif")) {
             entry->type = FileInfo::AnimatedImageType;
         } else if (mimeTypeName.startsWith(QStringLiteral("image/"))) {
             entry->type = FileInfo::RasterImageType;
         }
 
         if (entry->type != FileInfo::VideoType) {
             QImageReader reader(source.toLocalFile());
             auto size = reader.size();
             if (size.isValid()) {
                 entry->width = size.width();
                 entry->height = size.height();
             } else {
                 auto image = reader.read();
                 entry->width = image.width();
                 entry->height = image.height();
             }
         }
 
         QMetaObject::invokeMethod(
             cache(),
             [entry]() {
                 cache()->readingFinished(entry->source, entry);
             },
             Qt::QueuedConnection);
     }
 };
 
 FileInfoCache::FileInfoCache()
     : QObject(nullptr)
 {
     // Since the runnable is mostly IO bound, there is not really any reason to
     // execute more than one of it in parallel.
     threadPool.setMaxThreadCount(1);
 }
 
 std::shared_ptr<FileInfoCacheEntry> FileInfoCache::get(const QUrl &url)
 {
     if (!url.isValid()) {
         return nullptr;
     }
 
     if (cache.contains(url)) {
         return cache.value(url);
     }
 
     return nullptr;
 }
 
 void FileInfoCache::read(const QUrl &url)
 {
     auto runnable = new FileInfoRunnable;
     runnable->source = url;
     threadPool.start(runnable);
 }
 
 void FileInfoCache::readingFinished(const QUrl &source, std::shared_ptr<FileInfoCacheEntry> entry)
 {
     if (entry) {
         cache.insert(source, entry);
     }
     Q_EMIT cacheUpdated(source);
 }
 
 FileInfo::FileInfo(QObject *parent)
     : QObject(parent)
 {
     connect(cache(), &FileInfoCache::cacheUpdated, this, &FileInfo::onCacheUpdated);
 }
 
 FileInfo::~FileInfo() = default;
 
 QUrl FileInfo::source() const
 {
     return m_source;
 }
 
 void FileInfo::setSource(const QUrl &source)
 {
     if (m_source == source) {
         return;
     }
 
     m_source = source;
     Q_EMIT sourceChanged();
 
     auto result = cache()->get(source);
     if (!result) {
         setStatus(Reading);
         cache()->read(source);
         return;
     }
 
     m_info = result;
     Q_EMIT infoChanged();
 
     setStatus(Ready);
 }
 
 FileInfo::Status FileInfo::status() const
 {
     return m_status;
 }
 
 QString FileInfo::mimeType() const
 {
     if (!m_info) {
         return QString{};
     }
 
     return m_info->mimeType;
 }
 
 FileInfo::Type FileInfo::type() const
 {
     if (!m_info) {
         return UnknownType;
     }
 
     return m_info->type;
 }
 
 int FileInfo::width() const
 {
     if (!m_info) {
         return -1;
     }
 
     return m_info->width;
 }
 
 int FileInfo::height() const
 {
     if (!m_info) {
         return -1;
     }
 
     return m_info->height;
 }
 
 void FileInfo::setStatus(FileInfo::Status newStatus)
 {
     if (newStatus == m_status) {
         return;
     }
 
     m_status = newStatus;
     Q_EMIT statusChanged();
 }
 
 void FileInfo::onCacheUpdated(const QUrl &source)
 {
     if (source != m_source) {
         return;
     }
 
     auto result = cache->get(source);
     if (result) {
         m_info = result;
         Q_EMIT infoChanged();
 
         setStatus(Ready);
     } else {
         setStatus(Error);
     }
 }
 
 #include "fileinfo.moc"