fix Fingerprint issue with older Samsung devices (IsHardwareDetected=false). Now fallback correctly to Samsung Fingerprint API.

src/keepass2android/FingerprintSetupActivity.cs

@@ -126,9 +126,7 @@ namespace keepass2android
 				TrySetupSamsung();
 				
 			}
-			FindViewById(Resource.Id.container_fingerprint_unlock).Visibility = _samsungFingerprint == null
+			
-				? ViewStates.Visible
-				: ViewStates.Gone;
 		}
 
 		private bool TrySetupSamsung()
@@ -142,6 +140,9 @@ namespace keepass2android
 					SetError(Resource.String.fingerprint_no_enrolled);
 				}
 				ShowRadioButtons();
+				FindViewById(Resource.Id.container_fingerprint_unlock).Visibility = _samsungFingerprint == null
+					? ViewStates.Visible
+					: ViewStates.Gone;
 				return true;
 			}
 			catch (Exception)

src/keepass2android/QuickUnlock.cs

@@ -140,7 +140,10 @@ namespace keepass2android
 			RegisterReceiver(_intentReceiver, filter);
 
 			if ((int) Build.VERSION.SdkInt >= 23)
-				RequestPermissions(new[] {Manifest.Permission.UseFingerprint}, FingerprintPermissionRequestCode);
+			{
+				Kp2aLog.Log("requesting fingerprint permission");
+				RequestPermissions(new[] { Manifest.Permission.UseFingerprint }, FingerprintPermissionRequestCode);
+			}
 			else
 			{
 				
@@ -157,6 +160,9 @@ namespace keepass2android
 
 		public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
 		{
+			Kp2aLog.Log("OnRequestPermissionsResult " + (requestCode == FingerprintPermissionRequestCode) +
+			            ((grantResults.Length > 0) && (grantResults[0] == Permission.Granted)));
+			
 			if (requestCode == FingerprintPermissionRequestCode && grantResults[0] == Permission.Granted)
 			{
 				var btn = FindViewById<ImageButton>(Resource.Id.fingerprintbtn);
@@ -169,11 +175,13 @@ namespace keepass2android
 					b.Show();
 				};
 				_fingerprintPermissionGranted = true;
+				Kp2aLog.Log("_fingerprintPermissionGranted");
 			}
 		}
 
 		public void OnFingerprintError(string message)
 		{
+			Kp2aLog.Log("fingerprint error: " + message);
 			var btn = FindViewById<ImageButton>(Resource.Id.fingerprintbtn);
 
 			btn.SetImageResource(Resource.Drawable.ic_fingerprint_error);
@@ -187,6 +195,7 @@ namespace keepass2android
 
 		public void OnFingerprintAuthSucceeded()
 		{
+			Kp2aLog.Log("OnFingerprintAuthSucceeded");
 			_fingerprintIdentifier.StopListening();
 			var btn = FindViewById<ImageButton>(Resource.Id.fingerprintbtn);
 
@@ -206,6 +215,7 @@ namespace keepass2android
 		}
 		private void InitFingerprintUnlock()
 		{
+			Kp2aLog.Log("InitFingerprintUnlock");
 			var btn = FindViewById<ImageButton>(Resource.Id.fingerprintbtn);
 			try
 			{
@@ -221,23 +231,28 @@ namespace keepass2android
 				if (_fingerprintPermissionGranted)
 				{
 					FingerprintModule fpModule = new FingerprintModule(this);
+					Kp2aLog.Log("fpModule.FingerprintManager.IsHardwareDetected=" + fpModule.FingerprintManager.IsHardwareDetected);
 					if (fpModule.FingerprintManager.IsHardwareDetected) //see FingerprintSetupActivity
 						_fingerprintIdentifier = new FingerprintDecryption(fpModule, App.Kp2a.GetDb().CurrentFingerprintPrefKey, this,
 							App.Kp2a.GetDb().CurrentFingerprintPrefKey);
+					else _fingerprintIdentifier = null; //force re-init Samsung
 				}
 				if (_fingerprintIdentifier == null)
 				{
 					try
 					{
+						Kp2aLog.Log("trying Samsung Fingerprint API...");
 						_fingerprintIdentifier = new FingerprintSamsungIdentifier(this);
 						btn.Click += (sender, args) =>
 						{
 							if (_fingerprintIdentifier.Init())
 								_fingerprintIdentifier.StartListening(this, this);
 						};
+						Kp2aLog.Log("trying Samsung Fingerprint API...Seems to work!");
 					}
 					catch (Exception)
 					{
+						Kp2aLog.Log("trying Samsung Fingerprint API...failed.");
 						FindViewById<ImageButton>(Resource.Id.fingerprintbtn).Visibility = ViewStates.Gone;
 						return;	
 					}
@@ -246,11 +261,13 @@ namespace keepass2android
 
 				if (_fingerprintIdentifier.Init())
 				{
+					Kp2aLog.Log("successfully initialized fingerprint.");
 					btn.SetImageResource(Resource.Drawable.ic_fp_40px);
 					_fingerprintIdentifier.StartListening(this, this);
 				}
 				else
 				{
+					Kp2aLog.Log("failed to initialize fingerprint.");
 					//key invalidated permanently
 					btn.SetImageResource(Resource.Drawable.ic_fingerprint_error);
 					btn.Tag = GetString(Resource.String.fingerprint_unlock_failed);
@@ -261,6 +278,7 @@ namespace keepass2android
 			}
 			catch (Exception e)
 			{
+				Kp2aLog.Log("Error initializing Fingerprint Unlock: " + e);
 				btn.SetImageResource(Resource.Drawable.ic_fingerprint_error);
 				btn.Tag = "Error initializing Fingerprint Unlock: " + e;
 
@@ -335,6 +353,7 @@ namespace keepass2android
 			base.OnPause();
 			if (_fingerprintIdentifier != null)
 			{
+				Kp2aLog.Log("FP: Stop listening");
 				_fingerprintIdentifier.StopListening();
 			}
 		}