Fingerprint BiometricPrompt on android P from a View

Question

I am using FingerprintManager to authenticate my app with fingerprint. I have and android View with the fingerprint ui and when the FingerprintManager.authenticate callbacks are called I handle the callbacks in the view, e.g change fingerprint icon, error text etc.

Now in Android P, I have to use BiometricPrompt, which is easy enough to use, but forces me to have an Activity in order to work properly

Is there a way to make BiometricPrompt work in a plain android view?

this is my working code to launch the prompt in an activity

    Signature signature = createSignature();
    biometricPrompt = new BiometricPrompt.Builder(context)
            .setDescription("Description")
            .setTitle("Title")
            .setSubtitle("Subtitle")
            .setNegativeButton("Cancel", context.getMainExecutor(), new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    Log.i(TAG, "Cancel button clicked");
                }
            })
            .build();

        biometricPrompt.authenticate(new BiometricPrompt.CryptoObject(signature), cancellationSignal, context.getMainExecutor() , new BiometricPrompt.AuthenticationCallback() {...}

where context is an activity that without it it can not work

_"Now in Android P, I have to use BiometricPrompt"_ Depends on what you mean by _"have to"_; `FingerprintManager` is deprecated, but it's still available, _"where context is an activity"_ I don't see anything in the documentation about it having to be an `Activity` specifically. Looking at the source code for `BiometricPrompt`, all it uses the context for is to call `getSystemService` and `getPackageManager`. Since you already need a `Context` to get a `FingerprintManager`, have you tried just using that same context to create a `BiometricPrompt`? — Michael, Mar 18 '19 at 10:10
Yes, and I have received `onAuthenticationError` automatically. also, when using FingerprintManager in android P, also `onAuthenticationError` is called automatically the working code of FingerprintManager deployed in production, doesn't work for my users in android P, therefor this question was raised p.s. I also looked in BiometricPrompt source code and saw plain Context, and not activity. so this is weid for me as well — BennyP, Mar 18 '19 at 10:33
_"when using FingerprintManager in android P, also onAuthenticationError is called automatically"_ I've used `FingerprintManager` successfully on both Android P (Galaxy S10) and Android Q Beta (Pixel 3). — Michael, Mar 18 '19 at 10:37
interesting, I'll take a look. can you paste a sample code so I can maybe see the differences? — BennyP, Mar 18 '19 at 11:03

score 0 · Accepted Answer · answered Mar 21 '19 at 06:15

0

After going over the comments I have received in the question thread, I saw that the problem was in cancellationSignal, FingerprintManager does work in Android P as well as BiometricPrompt in views,

The actual problem was on Samsung devices (Note9 , S10) running android P, when using FingerprintManager a transparent screen will appear and cover the view I had cancelationSignal.cancel in onDetach that would break the entire auth flow. On other devices it makes sense, since the user can close the fingerprint screen on demand

answered Mar 21 '19 at 06:15

BennyP

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Hi, @BennyP. Do you have any ideas about how to disable the "transparent screen" popped up by the Samsung devices (S10). My app has its own fingerprint prompt dialog and I don't want the users to see 2 overlapped prompt screens. Thanks! – Yanni Chang Mar 01 '20 at 16:45
there is no way afaik, you can use BiometricPrompt to customize your message to the user – BennyP Mar 02 '20 at 06:00

Fingerprint BiometricPrompt on android P from a View

1 Answers1