Display previews

[PVince81]

• display preview in file list: use mediaSource plugin in Phoenix to connect to Webdav preview API to generate one like we did in core
  • oc-file addition: Added iconUrl to oc-file element owncloud-design-system#678
  • add icon URL to file lists
• display preview at the top of sidebar ?
• where to get the default thumbnail sizes ?
  • might be in old PHP template
  • need a way to retrieve from user settings ?
• only show previews if previews are enabled: https://github.com/owncloud/core/blob/master/core/js/config.php#L207
  • REQUIRES: capability: TODO raise core ticket
• get enabled mime types to find out whether we should attempt retrieving a preview or whether to fall back directly to an icon: https://github.com/owncloud/core/blob/master/core/js/config.php#L208
  • REQUIRES: capability: Preview API: expose supported file/MIME types via Capabilities endpoint core#31267

[DeepDiver1975]

• preview as thumbnail in the file list row

I wonder if this are really hard requirements for the frontend.

Cons:

• small previews are almost impossible to view
• heavy computation is required to create/deliver a lot of previews
• personal opinion: they have never been usefull

[PVince81]

Previews would start to become interesting once we get to implement a grid view of files (like gallery). Indeed the previews are rather small and even for pictures it doesn't show much.

[PVince81]

The previews will be retrieved using the Webdav API like OC 10 has.

[PVince81]

• cannot send Bearer token through headers, so need to use fetch() API to retrieve the image data and then pack them into "data:" URLs
• no cookies
• not related to CORS

=> would require pre-signed URLs on OC 10 side

So far the current logic is ok for images but would require the pre-signed URL approach for videos.

[PVince81]

@C0rby ^

[PVince81]

to clarify, we already have an implementation that uses the preview endpoint in the media viewer app, and the approach above is what I described, see:

• thumb path: https://github.com/owncloud/phoenix/blob/master/apps/media-viewer/src/Mediaviewer.vue#L181
• media source blob fetching and repacking as data URL: https://github.com/owncloud/phoenix/blob/master/src/plugins/mediaSource.js#L13

[PVince81]

similar topic happens for downloads: #526 (comment)

for the scope of this sprint I suggest focusing only on bringing the same logic to the file list and its thumbnail retrieval.

later on we can look into pre-signed URL as part of https://github.com/owncloud/enterprise/issues/3912

[PVince81]

updated top post with some findings

[butonic]

server side merged with owncloud/ocis#157

[PVince81]

PR for file previews in file list was merged: #3187

next up is adding a preview on top of the sidebar and solving the further points

[pascalwengerter]

We're now able to display thumbnails and do so for certain file types in the files list/table. There's also discussions about having larger previews in the sidebar or on a grid view, but that's a different story.

If further previews are needed please open a new ticket.

[phil-davis]

Note: the last entries in expected-failures linked to this issue are removed in PR #5787