BugFix - Use New Thumbnail Key for Thumbnail Generation

[alperozturk96]

• Tests written, or not not needed

The OCFile remoteId is currently being used as the imageKey for thumbnail generation. This approach prevents the correct regeneration of thumbnails when a user uploads a different file with the same filename and extension.

Example:

1. User uploads aa.jpg (479 KB) → Thumbnail is generated.
2. User replaces it with aa.jpg (2124 KB) → Thumbnail is not regenerated because the remoteId remains unchanged.

Proposed Solution:

To ensure proper thumbnail generation, the getThumbnailKey() should be used as the imageKey instead of the remoteId.

Known Issues:

The ConflictResolveDialog is currently unable to display thumbnails correctly in both the master branch and this PR. This issue will be addressed separately in a future PR.

Before

befd.mp4

After

after_generation.mp4

[alperozturk96]

/backport to stable-3.31

[tobiasKaminsky]

I think we need to discuss this approach.
First "problem" that comes to my mind:

• create an image
• let Android generate thumbnail with etag "123"
• rename file
  --> new etag
  -> thus new thumbnail

[alperozturk96]

I think we need to discuss this approach. First "problem" that comes to my mind:

• create an image
• let Android generate thumbnail with etag "123"
• rename file
  --> new etag
  -> thus new thumbnail

Exactly. In that case, it will regenerate the thumbnail. We can evaluate the pros and cons of this approach. If the advantages outweigh the disadvantages, we can proceed with this method. Alternatively, we can try to find a more distinct and reliable solution, maybe using a combination of remoteId, size, and hash, which may have fewer side effects.

[ZetaTom]

Using only remoteId as a key for our thumbnail cache also causes other problems. The Shared tab is notoriously difficult to work with, as it solely relies on the data returned by the sharing API. In this case, remoteId is no set, which is why the default placeholder thumbnail is displayed instead. (See #14437) Because of this, I think we should re-evaluate what key to use.

[github-actions]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/14513.apk



To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.

[github-actions]

Codacy

Lint

Type	master	PR
Warnings	54	54
Errors	3	3

SpotBugs

Category	Base	New
Bad practice	65	65
Correctness	58	58
Dodgy code	294	295
Experimental	1	1
Internationalization	7	7
Malicious code vulnerability	1	1
Multithreaded correctness	7	7
Performance	51	55
Security	18	18
Total	502	507

SpotBugs increased!

[github-actions]

blue-Light-Screenshot test failed: https://www.kaminsky.me/nc-dev/android-integrationTests/14513-Screenshot-blue-Light-09-52

[alperozturk96]

I discussed with @tobiasKaminsky . isUpdateThumbnailNeeded() will be used for solving this problem.

[alperozturk96]

#14556