Use public preview api to retrieve thumbnails

[abelgardep]

Implements #2926 and #2927

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QA

Bugs & improvements:

• (1) etag field is empty Use public preview api to retrieve thumbnails #3017 (comment)
• (2) checking for updates is not only for images Use public preview api to retrieve thumbnails #3017 (comment) [DONE]
• (3) Txt thumbnail updates not reflected Use public preview api to retrieve thumbnails #3017 (comment) [WONT FIX HERE]

[jesmrec]

Let's QA this one

[jesmrec]

(1)

I've checked out the requests and they have the following form:

/remote.php/dav/files/user1/ownCloud%20Manual.pdf?x=336&y=336&c=&preview=1

• c parameter is empty. It use to contain the etag. Is that intended somehow?
• I lack of an API doc, so i checked the iOS client who actually implements that API. This is how an iOS request looks like:

Archive.zip?y=120&preview=1&x=120&c=%22483f40d8166bcebaab085ea9cca57a79%22&a=1

it contains also an a parameter. By checking the iOS code:

request.parameters = [NSMutableDictionary dictionaryWithObjectsAndKeys:
				@(size.width).stringValue, 	@"x",
				@(size.height).stringValue,	@"y",
				item.eTag, 			@"c",
				@"1",				@"a", // Request resize respecting aspect ratio 
				@"1", 				@"preview",
			nil];

should we include also the a to keep a correct ratio?

[jesmrec]

(2) [DONE]

@abelgardep as you commented me, this part of the code:

if (!updatedLocalFile.isFolder() &&
                        remoteFile.isImage() &&
                        remoteFile.getModificationTimestamp() != localFile.getModificationTimestamp()) {
                    updatedLocalFile.setNeedsUpdateThumbnail(true);

should be changed, since not only images contain a thumbnail.

[jesmrec]

(3) [WONT FIX]

1. In an account, sync a folder that contains an txt file. Thumbnail is shown
2. In server, modify the txt file including some different text on the top (where the thumbnail pic is rendered)
3. Sync the folder / download the new version of the file

Current: Thumbnail does not change
Expected: Thumbnail change to show the new content

Same behaviour works fine with images

Pixel 2 Android 11
b34f119

[jesmrec]

(1) -> etag is sent fro mthe moment it is stored in the DB.

[abelgardep]

I think that (2) and (3) refers to the same problem and should be fixed now. We will ask for new thumbnails when something changes in the server even if it is not an image (Previous behaviour).

[jesmrec]

About (2) and (3)

Thumbnails of txt files are correctly updated only if the file is not downloaded, and with a browsing back and forth. That means, with steps:

1. txt is not downloaded in the app
2. in web or other client, modify the txt
3. in the app, pull down to refresh the containing folder

Result: thumbnail not refreshed

4. in the app, browse to other folder and browse back to the containing folder

Result: thumbnail is now refreshed

5. tap on the txt file to download
6. close the file, so you are again in the list of files
7. in web or other client, modify the txt
8. in the app pull down to refresh the containing folder

Result: thumbnail not refreshed

9. browse to another folder and then browse back to the containing folder

Result: thumbnail not refreshed

Expected: refresh should realise on the new version. Downloaded files must refresh also the thumbnail

NOTE:

Updating an non-downloaded image, makes the thumbnail to upload with only a refresh. If the image is downloaded, it runs into another issue (#3021). The current report is oriented to txt files behaviour.

Pixel 2 Android 11
4ec916e

[abelgardep]

That's the behaviour since the beginning. If the file is available locally, we extract the thumbnail from the local file. The problem here is that the local thumbnail extraction seems not to work with txt files. So, the thumbnail is not updated.

[jesmrec]

So, we have two different issues regarding previews:

• For txt files. We can not extract thumbnails from downloaded files.

• For images. If a downloaded image changes, thumbnail is not updated and you see the preview of the old version.

Any solution for this? getting rid of the local thumbnails and use only remote thumbnails, even when the file is locally downloaded? it will increase the number of request, but is any case we are going to request preview for every file. This will be addressed in a different ticket, for sure.

Which are the expectations @michaelstingl?

[abelgardep]

it will increase the number of request, but is any case we are going to request preview for every file

We only request thumbnails the first time and then if something changes in the server, but not always. If file is available locally we don't request for new thumbnails at the moment.

[jesmrec]

We only request thumbnails the first time and then if something changes in the server, but not always. If file is available locally we don't request for new thumbnails at the moment.

yes, for this reason, a posible solution would be requesting always the remote thumbnails, so that the preview is always updated. But first, we have to know the expectations for this feature.

[jesmrec]

After discussions and calls, the final conclusion is that thumbnail and preview updates will need more elaboration. It will be moved to another issue (#3024):

Goals of the current PR:

• Replace the old endpoint with the new Preview API
• Request for every file. Pending: request also for downloaded. This will be moved to the new issue.