Using org.nemomobile.socialcache: cache located at privileged location

[nephros]

I am creating an app which downloads many images and would like to cache them locally.

So I came across the org.nemomobile.socialcache plugin, which has a generic SocialImageCache type.

Playing around with it I got it to the point where it actually downloads my image and tries to store it in the cache.

Note I do not actually have any Account corresponding to the image data, so I do not use any of the Accounts management, and call imageFile() with some nulls.

import QtQuick 2.6
import org.nemomobile.socialcache 1.0

 ListModel { id: imgModel }
 SocialImageCache{ id: imgCache
     property SocialImageCache downloader: SocialImageCache{}
  }


GridView {
     model: imgModel
     delegate: Image { id: imgDelegate
     ...
     property SocialImageCache downloader: imgCache.downloader

     // called by downloader.imageFile
     function imageCached(imageFile) {
         imgDelegate.source = imageFile
      }

      function download(url) }
        downloader.imageFile(url, null, imgDelegate, null, imageId, null)
      }
    }
}

But we then fail with:

18:10:06.968 unknown:0  AbstractImageDownloader::about to fetch image: "http://example.org/123/56789/icon.jpg"
18:10:06.980 unknown:0  Unable to write downloaded image data to file: "/home/nemo/.local/share/system/privileged/Images/cache/b/b5160b690283d8b66d3af07524252c57.jpg"
18:10:06.981 unknown:0  SocialImageDownloader: failed to download  ""

I can see that that location is set at compile time to the privileged directory:

• https://github.com/sailfishos/libsocialcache/blob/master/src/qml/generic/socialimagedownloader.cpp#L221

• https://github.com/sailfishos/libsocialcache/blob/master/common.pri#L3

My Questions:

1. What are other tools available to locally cache larger amounts of remote files such as images and media files? (I tried Nemo.Thumbnailer but that doesn’t work with non-local files).
2. is using an “Account” through the Sailfish Accounts management mandatory for using libsocialcache so we get access to that location?
3. Could it be considered a bug or useful enhancement to request a cache being available at a user-writable location?