Android 11: How/where to write mixed media files that should survive uninstall

Question

I am writing a specific use-case camera app that targets Android 11. When I hit record I would like to create a new directory somewhere (with a name based on the timestamp etc) that contains the resulting video as well as a whole heap of other custom YAML/JSON/CSV files that also get written during the recording process (belongs logically to the "output" of the recording).

I would like all of the generated files to survive an app uninstall/reinstall as I do not want to risk users losing everything they've ever recorded if they uninstall the app. How do I do this with the new scoped storage changes etc in Android 11?

Looking at the overview here, I can see that:

• App-specific files, App preferences and Database are clearly not suitable as amongst other things these files do not survive an uninstall
• Documents and other files uses the Storage Access Framework, but this is not suitable because it requires a system file picker every time you want to write something. This would disrupt the flow of recording/user experience, and no camera app works like that.
• Datasets/BlobStoreManager (here) also is not appropriate for my use case.
• MediaStore API looks like it should be the one, but it can't seem to do what I want in terms of producing a whole directory of outputs, including custom YAML/JSON/CSV text files, that all belong together. My aim is that the user at all times can simply go to the file explorer, navigate to the appropriate folder, and just copy out the folder(s) with the recordings to their computer or whatever, to save/view the data. Even MediaStore.Files does not seem to guarantee you can actually do that if your app is using scoped storage.

The only option that seems to be left is using MANAGE_EXTERNAL_STORAGE and putting the data wherever I want in the home directory, but that seems like a bit of an extreme permission to be asking for just in order to be able to save some text files along with my produced videos. Also, that permission is Android 11 specific. If I want to support older Android versions, what would I need to do?

What is my best choice here? Is there an option I've missed?

Answer 1

but this is not suitable because it requires a system file picker every time you want to write something

No.

Use ACTION_OPEN_DOCUMENT_TREE to let the user pick a document tree. In there, you can create your own sub-tree and put your own documents into that sub-tree. You do not need the "system file picker" for anything beyond the initial ACTION_OPEN_DOCUMENT_TREE request itself. And the resulting documents will survive an uninstall.