Method createThumbnails

src/gui/UBThumbnailScene.cpp:191–226

* @brief Create thumbnails for this scene. * * Thumbnails for the document pages above startIndex are asynchronously * loaded and positioned on the scene. The application remains responsive * even while loading thumbnails. * * It is even possible to interact with the already loaded thumbnails during * the loading process. So the already loaded pages can be moved, copied, * deleted or opene

 * continues in background.
 */
void UBThumbnailScene::createThumbnails(int startIndex)
{
    // skip already loaded thumbnails
    while (startIndex < mThumbnailItems.count() && mThumbnailItems.at(startIndex))
    {
        ++startIndex;
    }

    // create the list of all thumbnail paths
    QList<std::pair<int,QString>> paths;

    for (int index = startIndex; index < mDocument->proxy()->pageCount(); ++index)
    {
        paths << std::pair<int,QString>{index, UBThumbnailAdaptor::thumbnailUrl(mDocument->proxy(), index).toLocalFile()};
    }

    // start background loading of files
    if (mLoader)
    {
        // abort a running loader
        mLoader->abort();
        delete mLoader;
        mLoader = nullptr;
    }

    if (paths.empty())
    {
        return;
    }

    mLoader = new UBBackgroundLoader{paths, this};
    mLoader->start();

    // now create all missing thumbnails for document as they arrive from the loader
    loadNextThumbnail();
}

/**
 * @brief Insert a thumbnail.