[BUG] Some images previews are visible on web interface and not on Android app

[Anycubic]

Actual behaviour

Installed and uninstalled the app many times. First time it runs all of the images have their preview (folder with more than 2000 images but it happens regardless of the number of images stored in a folder). After the 2nd time I run owncloud app some previews are not visible anymore. If I actually open one of that images without the preview, the preview will "stick" and will not disappear anymore. Each and every time I close and reopen the app, previews are randomly visible or not visible.

Expected behaviour

All images previews should be always visible in each and every folder, every time I run the app.

Steps to reproduce

1. Instal the app, run it first time, open a folder, previews are all there
2. Re-run the app -> not all of the previews are visible anymore
3. If I open the web interface images previews are all there, so I guess it is an app bug

Can this problem be reproduced with the official owncloud server?
(url: https://demo.owncloud.org, user: test, password: test)
I don't know

Environment data

Android version:
14
Device model:
Xiaomi 12 Pro
Stock or customized system:
Stock
ownCloud app version:
4.3.0
ownCloud server version:
10.14.0.3

Logs

Web server error log

Insert your webserver log here

ownCloud log (data/owncloud.log)

Insert your ownCloud log here

[jesmrec]

previews means thumbnails, right? the little image on the left. On my side, i can not reproduce it, thumbnails are there. That images are generated in the server and retrieved from there, so, there is also some dependency on that side. Will take a look again anyway.

If you can provide logs, or also, a test account in your server (we'd tell you how to give that information in a secure way), it could be helpful for dev team.

[Anycubic]

thumbnails

Yep, I meant thumbnails. The same goes for video, pdf, txt etc etc. I have the same behaviour also on a tablet of mine, total erratic behaviour, sometime thumbnails appear sometime not. On the web interface (I tested also the very beautiful "web app") no problems at all, both on desktop and mobile browser. I could provide for sure a test account if you need it, just let me know, thanks.

[jesmrec]

In case of the Android app, only the thumbnails that server retrieves are shown in the app: images and txt files. PDFs and other formats lack of server generated thumbnails. Don't compare with desktop client because are pretty different scopes and work in a different way. I will provide you a place where you can push the info. Thanks a lot!

[Anycubic]

In case of the Android app, only the thumbnails that server retrieves are shown in the app: images and txt files. PDFs and other formats lack of server generated thumbnails. Don't compare with desktop client because are pretty different scopes and work in a different way. I will provide you a place where you can push the info. Thanks a lot!

Ok, at least I know there is no problem with PDFs and other formats. Nevertheless images thumbnails are not working as intended. Please have a look at attached screenshots.

[jesmrec]

https://infinite.owncloud.com/s/nYSfrsmANDXWKzJ

Pwd: aa55AA..

There, you can upload any file with information about your test server. We strongly appreciate your feedback.

[Anycubic]

https://infinite.owncloud.com/s/nYSfrsmANDXWKzJ

Pwd: aa55AA..

There, you can upload any file with information about your test server. We strongly appreciate your feedback.

Ok. What do you need? Logs with a certain details of logging? I can't seen any error at "error" log level.

[jesmrec]

it's enough with information about a test server. Logs could help as well.

[benedictgoodman]

I have the same issue, and can't see anything in the log. It has persisted across multiple versions of the android app. Is this the same as #3525 ?

[Anycubic]

I have the same issue, and can't see anything in the log. It has persisted across multiple versions of the android app. Is this the same as #3525 ?

@benedictgoodman it is exactly the same. I made some tests, deleted a folder with issues and shared again and the problem disappeared. So I guess that bug is still there. Actually images preview from Android is unusable, I can't believe it is a rare thing, I have the same behaviour on another android tablet as well.

[jesmrec]

I have the same issue, and can't see anything in the log. It has persisted across multiple versions of the android app. Is this the same as #3525 ?

i don't think so. In that issue, problem happens only in grid view, now you reported the problem in list view, right? Checked again, i see all thumbnails in two different servers/devices. We can not control every single server (don't forget, server is who generates the thumbnails, not the mobile device), for that reason we'd need extra info about the problem in logs, or in a test account.

[Anycubic]

I have the same issue, and can't see anything in the log. It has persisted across multiple versions of the android app. Is this the same as #3525 ?

i don't think so. In that issue, problem happens only in grid view, now you reported the problem in list view, right? Checked again, i see all thumbnails in two different servers/devices. We can not control every single server (don't forget, server is who generates the thumbnails, not the mobile device), for that reason we'd need extra info about the problem in logs, or in a test account.

How can I give a temp account detail to you in a private fashion?

[jesmrec]

How can I give a temp account detail to you in a private fashion?

#4443 (comment)

[Anycubic]

How can I give a temp account detail to you in a private fashion?

#4443 (comment)

Did it

[jesmrec]

Thanks @Anycubic but i only see credentials without a server URL to attach them to.

[Anycubic]

@jesmrec sorry I re-uploaded the file

[jesmrec]

Checking with your server, where i pushed a big amount of thumbnailed files (txt and images). Thumbnails loaded correctly. I will clarify how the thumbnails feature works:

• Only txt files and images (not all formats are supported). Thumbnails are generated in server and mobile app retrieves them
• Mobile app retrieves thumbnails one by one, and then loaded. This is not very performant and we are aware of it.
• Mobile app asks the server for the thumbnails at the time you scroll down. That means, in a list of 2000 files, the latest file will ask for its thumbnail when it is on the screen, not before. If you don't scroll down, only thumbnails on the top of the list are fetched.
• If you scroll down very fast in a long list of files, the files on the bottom will take some time to appear. This is a collateral effect of the one-by-one operation.
• Thumbnails are cached. Only retrieved the first time.

Checking the steps on the top message.

Re-run the app -> not all of the previews are visible anymore

are there thumbnails that were visible, and then not-visible?? anything that happened in the middle?

[Anycubic]

Checking with your server, where i pushed a big amount of thumbnailed files (txt and images). Thumbnails loaded correctly. I will clarify how the thumbnails feature works:

• Only txt files and images (not all formats are supported). Thumbnails are generated in server and mobile app retrieves them
• Mobile app retrieves thumbnails one by one, and then loaded. This is not very performant and we are aware of it.
• Mobile app asks the server for the thumbnails at the time you scroll down. That means, in a list of 2000 files, the latest file will ask for its thumbnail when it is on the screen, not before. If you don't scroll down, only thumbnails on the top of the list are fetched.
• If you scroll down very fast in a long list of files, the files on the bottom will take some time to appear. This is a collateral effect of the one-by-one operation.
• Thumbnails are cached. Only retrieved the first time.

Checking the steps on the top message.

Re-run the app -> not all of the previews are visible anymore

are there thumbnails that were visible, and then not-visible?? anything that happened in the middle?

I started again from scratch. Uninstalled the app on Android, installed again. I opened "CameraUpload" folder where I have more than 2k photos and waited for all of the thumbnails to get loaded, eveything ok. I than opened another folder, thumbnails where not there and not being loaded. Went back to "CameraUpload" folder and thumbnails disappeared!
I then stopped the app, re-opened it and CameraUpload folder was not showing a single thumbnail while other folders started to populate (the same folders which didn't show anything during the first run after reinstall cycle).
The third time I opened the app also that folders which started to show thumbnails started to get "crazy" and showing not all of the previews (?).
To wrap up:

• uninstalling and reinstalling the app DOES something
• unfortunately the app starts to show and hide previews in a total random pattern (again)
• loading a picture (tapping it) actually makes its preview appear again
• no problem at all on web side

[benedictgoodman]

Thanks @jesmrec for looking at this. Just to say that my experience is exactly the same as @Anycubic above. No issue on the server in terms of preview generation, and the first time you open a folder in the android app the previews all pop up fine (the speed that they appear seems fine to me). The issue arises when you open a folder in the app again subsequently. Sometimes the previews are still there, sometimes they're gone, and once they're gone it seems they don't come back unless you reinstall the app.

[jesmrec]

I started again from scratch. Uninstalled the app on Android, installed again. I opened "CameraUpload" folder where I have more than 2k photos and waited for all of the thumbnails to get loaded, eveything ok. I than opened another folder, thumbnails where not there and not being loaded. Went back to "CameraUpload" folder and thumbnails disappeared!
I then stopped the app, re-opened it and CameraUpload folder was not showing a single thumbnail while other folders started to populate (the same folders which didn't show anything during the first run after reinstall cycle).
The third time I opened the app also that folders which started to show thumbnails started to get "crazy" and showing not all of the previews (?).
To wrap up:

uninstalling and reinstalling the app DOES something
unfortunately the app starts to show and hide previews in a total random pattern (again)
loading a picture (tapping it) actually makes its preview appear again
no problem at all on web side

will check on that way, thanks again

[jesmrec]

Thanks @jesmrec for looking at this. Just to say that my experience is exactly the same as @Anycubic above. No issue on the server in terms of preview generation, and the first time you open a folder in the android app the previews all pop up fine (the speed that they appear seems fine to me). The issue arises when you open a folder in the app again subsequently. Sometimes the previews are still there, sometimes they're gone, and once they're gone it seems they don't come back unless you reinstall the app.

Thanks for the feedback, it's an strange issue, but there have to be something to fix.

[Anycubic]

Checking with your server, where i pushed a big amount of thumbnailed files (txt and images). Thumbnails loaded correctly. I will clarify how the thumbnails feature works:

@jesmrec I checked with images that you downloaded on my server and I can see the issue. Please have a look at the screenshot. The txt folder shows just a partial number of previews while on web client no issue at all. Testimages is ok. I guess there must be something in the Android app.

[jesmrec]

Thanks for adding, i did not reproduce in the initial attempts, i will do another check.

[jesmrec]

Well, i don't find a clear explanation about this problem. In fact, not easy to reproduce (kind of randomness). The point here would be going to the root, analyse the preview mechanism and check how to improve its performance, as far as we can (server is also involved).The only clear thing is that previews take longer as expected to preview when the amount of files is huge.

We could take a look about the local rendering as an improvement CC @Aitorbp @JuancaG05

Any other ideas are welcome.

[Anycubic]

As I said the issue is 100% present on both of my Android devices while I never reproduced it on any web interface (both Android and MacOS). I have thousands of pictures, I guess that this could be where to start