Finger

Additional

Language
Kotlin
Version
N/A
Created
Apr 5, 2017
Updated
Dec 11, 2019
Owner
adorsys GmbH & Co. KG (adorsys)
Contributors
emjeschke
asa06
Nino Handler (luckyhandler)
3
Activity
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Source code
APK file

Blurb

finger

This fingerprint library aims to make the use of fingerprint authentication in your application as simple as possible and is best suited for developers who just want to have to deal with 3 things:

  • was the fingerprint successfully accepted
  • was there an error while validating the fingerprint (and which) and provide custom error messages
  • show a system fingerprint dialog / biometric dialog without having to consider the API level or write boilerplate code

First, include finger in your project by adding

// add the finger and also the biometric dependency  
implementation "de.adorsys.android:finger:${latestFingerVersion}"
implementation "androidx.biometric:biometric:1.0.0"

usage

You can use finger as follows:

val finger = Finger(context) // will internally always use application context
finger.subscribe(object : FingerListener {
 override fun onFingerprintAuthenticationSuccess() {
      // The user authenticated successfully -> go on with your logic
     }
                  
 override fun onFingerprintAuthenticationFailure(errorMessage: String, errorCode: Int) {
      // Show the user the human readable error message and use the error code if necessary 
         // and subscribe again
 }
})
              
finger.showDialog(
            activity = this,
            strings = Finger.DialogStrings(
                title = getString(R.string.text_fingerprint),
                subTitle = "", // defaults to null if nothing is assigned    
                description = "", // defaults to null if nothing is assigned
                cancelButtonText = "login with password" // default parameter is android.R.cancel 
            )
        )

You should subscribe in onResume and unsubscribe in onPause:

override fun onResume() {
 super.onResume()
 finger.subscribe(this)
}

override fun onPause() {
    super.onPause()
    finger.unSubscribe()
}

error handling

finger usually emits the standard system error messages. But you can also assign finger a map of errors for each error type:

val errors = mapOf(
 Pair(BiometricPrompt.ERROR_HW_UNAVAILABLE, getString(R.string.error_override_hw_unavailable)),
 Pair(BiometricPrompt.ERROR_UNABLE_TO_PROCESS, getString(R.string.error_override_unable_to_process)),
 Pair(BiometricPrompt.ERROR_TIMEOUT, getString(R.string.error_override_error_timeout)),
 Pair(BiometricPrompt.ERROR_NO_SPACE, getString(R.string.error_override_no_space)),
 Pair(BiometricPrompt.ERROR_CANCELED, getString(R.string.error_override_canceled)),
 Pair(BiometricPrompt.ERROR_LOCKOUT, getString(R.string.error_override_lockout)),
 Pair(BiometricPrompt.ERROR_VENDOR, getString(R.string.error_override_vendor)),
 Pair(BiometricPrompt.ERROR_LOCKOUT_PERMANENT, getString(R.string.error_override_lockout_permanent)),
 Pair(BiometricPrompt.ERROR_USER_CANCELED, getString(R.string.error_override_user_cancel)),
 Pair(Finger.ERROR_NOT_RECOGNIZED, getString(R.string.error_override_not_recognized)))
val finger = Finger(applicationContext, errors)

Usually, errors is defined as an emptyMap() as default argument.

val finger = Finger(context = this)

or

val finger = Finger(context = this, errors = errors)

The latter uses only the system error messages if no own error message can be found in the map. So you can very well customize when to show which message.

Documentation

This project contains documentation. To generate it run ./gradlew finger:dokka. You will find it at project/documentation.

Proguard

-keep class de.adorsys.android.finger.**

-dontwarn de.adorsys.android.finger.**

Contributors

@luckyhandler