Avoid clipboard permissions prompt

[justinmc]

Currently, some Xiaomi devices show a permissions prompt when the clipboard is accessed. This is similar to iOS14, where we added the hasStrings method to not trigger this prompt (see flutter/flutter#60145). This uses native Android's hasText method to do the same sort of workaround in Android's hasStrings.

For flutter/flutter#74139, but probably needs a small framework change too.

[justinmc]

Does anyone know why clipboardHasStrings and hasPrimaryClip are always returning true? Is something being mocked here that I'm missing?

[justinmc]

Moving to hasText fixed this, so I'm going with that.

[hamdikahloun]

Maybe the permission will be prompt here if the clipboard data is URI :

engine/shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java

Line 340 in 69da37f

activity.getContentResolver().openTypedAssetFileDescriptor(item.getUri(), "text/*", null);

[LongCatIsLooong]

the documentation says hasText is deprecated: https://developer.android.com/reference/android/content/ClipboardManager#hasPrimaryClip()

[justinmc]

I tried hasPrimaryClip but it completely wasn't working for me in the tests. It seemed to always return true, even if I setPrimaryClip to null or did clearPrimaryClip. You can see how I had it before in 72c32b8. CC @blasten who was helping me with this on Discord. Is that a robolectric problem?

[hamdikahloun]

@justinmc Can you please clarify how hastext make the permission bypassed.
Hastext function throw security exception if the clip data is URI (image URI for example).

[justinmc]

@hamdikahloun It seemed to stop the Xiaomi permission prompt (see flutter/flutter#74139), but it was hard to verify. Are you sure this won't help if an image has been copied? We didn't try that I guess.

This is just for starting the app, where the framework checks the clipboard to decide if it should display the Paste button. If you actually paste, then the prompt will still show, which is what it should do.

Edit: The general idea is that previously, Android was always calling getPrimaryClip just to check if there was a string on the clipboard to paste, which triggered the prompt. With this PR, it would only call hasText.

[hamdikahloun]

Can you check this please : #21290 & flutter/flutter#66108 (comment)

[pedromassangocode]

Hastext function throw security exception if the clip data is URI (image URI for example).

@justinmc there is a hint here to check whether the clipboard data is a text or not:
https://developer.android.com/guide/topics/text/copy-paste#PastePlainText

It seems that the current implementation is not working flutter/flutter#74139 (comment). Can we build an release apk with hasPrimaryClip() just to verify its behavior? From my understanding it is not working just in tests.

[chinmaygarde]

@justinmc Any updates? If this issue is stalled, can we mark it WIP or close it till we can resume work it?

[chinmaygarde]

Closing it as stale. Feel free to re-open when progress can be made.

[justinmc]

Sorry I missed the notifications from this PR. It was the right decision to close for now. The problems are:

1. This PR doesn't seem to prevent the clipboard access dialog on XiaoMi.
2. Really we should be using hasPrimaryClip, but it doesn't seem to work with our engine tests.

I'm having trouble building an example with this using hasPrimaryClip due to engine compilation failing. Hopefully it's a temporary problem with the engine or my setup.