[Extension] thumbnails

[butonic]

while thumbnails should be a separate service it needs to respect the access permissions, otherwise it might leak information.

oCIS Extension based on #54

We can

• use a content hash of the original file and the thumbnail size for the name of the thumbnail, render it on the fly, cache it on the server side and in the browser. If you don't already have the content hash you can only brute force thumbnails. Without authentication an attacker might be able to iterate over known hashes, which might leak compromising information.
• optionally, to increase security, check if the user is logged in
• optionally, to increase security even further, check file permissions and deny thumbnail access if the user has no access.

They can be implemented incrementally.

[michaelstingl]

Previous pain or ideas around this topic…

• Aspect ratio / scale options Thumbnail generation: does not obey aspect ratio / max values for x and y core#16250 , Preview API: different aspect ratio / scale options core#31268
• Etag for previews Etag for previews / thumbnails core#35029
• Share thumbnails? Previews-thumbnails get out-of-sync when edited by sharer and sharee core#31855
• Run async / in background Migrate preview generation to async job execution core#11685
• Discussion around supported file/MIME types A mime type can be linked to many file formats core#13647 , Preview API: expose supported file/MIME types via Capabilities endpoint core#31267
• Multiple thumbnails services for different file types Migrate preview system to external preview server systems core#24424, Video preview (transcoded mp4) in the thumbnails folder core#24480
• Properly EXIF orientation parameters [Extension] thumbnails #10 (comment)
• Extract thumbnails embedded in EXIF Use exif thumbnail for image preview core#7232
• Support for modern media formats like HEIC (High Efficiency Image Coding) and HEVC (High Efficiency Video Coding), Add support heic core#30093, Feature request: HEIC support gallery#737, [iOS11] 3.6.2 can‘t display *.HEIC images ios-legacy#933

[michaelstingl]

@TheOneRing links for EXIF orientation madness:

• https://github.com/recurser/exif-orientation-examples
• https://www.daveperrett.com/articles/2012/07/28/exif-orientation-handling-is-a-ghetto/
• https://magnushoff.com/articles/jpeg-orientation/

Please check if this is properly handled by the library you're using.

[felixboehm]

PR is here cs3org/reva#298

• move to repo owncloud/ocis-thumbnails
• follow new oCIS extension framework oCIS Extensions #54

[PVince81]

On the front end side, the way I see it:

• files app must support fetching file thumbnails for displaying in the current file list: Display previews web#276
• optionally: we can provide a way to view bigger previews in the top of sidebar like we had in OC 10. Could be native or could be provided by an extension
• later on: gallery view frontend extension that either provides another view of the file list (needs extension point to register multiple views for the file list => Allow providing alternative file list views web#2585)

For finding out about preview URLs, multiple options:

1. reuse the same URL / path we had in OC 10 (by convention, keeps compatibility)
2. expose thumbnail URL in PROPFILE/filelist responses in all supported protocols (maybe MSGraph has this already?)

[DeepDiver1975]

MS Graph API already has a Thumbnail spec

[PVince81]

Had a chat with @TheOneRing to understand how the current implementation of the thumbnail server works. As far as I understood:

• the currently implemented thumbnail server:
  • receives a Webdav URL including authentication token and parameters for the thumbnail.
  • sends a request to the Webdav URL with HEAD (to check etag) and GET to receive the file in question
  • the response body of the first requests will contain the generated thumbnail
  • caches the requested thumbnails in memory (for now), so the HEAD / etag check can save having to do the Webdav request to get the thumbnail

[butonic]

As @DeepDiver1975 mentioned we should make the thumbnail service serve the endpoints as exposed in the ms graph api https://docs.microsoft.com/en-us/graph/api/driveitem-list-thumbnails?view=graph-rest-1.0&tabs=http

[PVince81]

As far as I can see it would require the router to let extensions register to dynamic routes, not only route prefixes. Here for example: /drives/{drive-id}/items/{item-id}/thumbnails

[PVince81]

Further ideas:

• the service could have the ability to pregenerate thumbnails when passing in a folder URL. it should then recursively traverse it and create thumbnails of all known file types in there with a standard/configured size, so they are pre-cached. This would be useful for gallery-like usage.
• do the pregeneration in a background job, or "just in time" after uploading

[michaelstingl]

Added support for modern media formats like HEIC & HEVC in #10 (comment)

[wkloucek]

thumbnails extension is there. Some more to do here?

[michaelstingl]

thumbnails extension is there. Some more to do here?

Link to qa/test results? Are my items from #10 (comment) already covered? Otherwise we'd need new issues…

[refs]

thumbnails extension is there. Some more to do here?

Link to qa/test results? Are my items from #10 (comment) already covered? Otherwise we'd need new issues…

I'd close this and take care of creating new issues addressing @michaelstingl comments 👍