Make sure a fingerprint is enrolled before showing the fingerprint option

app/src/main/java/me/impy/aegis/helpers/FingerprintUiHelper.java

@@ -0,0 +1,170 @@
+// This file was originally taken from https://github.com/googlesamples/android-FingerprintDialog/blob/2feb02945ae220ebd1bc2c2b620a1d43e30daea8/Application/src/main/java/com/example/android/fingerprintdialog/FingerprintUiHelper.java
+// It has been modified to suit Aegis' needs
+
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package me.impy.aegis.helpers;
+
+import android.Manifest;
+import android.content.Context;
+import android.hardware.fingerprint.FingerprintManager;
+import android.os.Build;
+import android.os.CancellationSignal;
+import android.support.annotation.RequiresApi;
+import android.widget.TextView;
+
+import com.mattprecious.swirl.SwirlView;
+
+import me.impy.aegis.R;
+
+/**
+ * Small helper class to manage text/icon around fingerprint authentication UI.
+ */
+@RequiresApi(api = Build.VERSION_CODES.M)
+public class FingerprintUiHelper extends FingerprintManager.AuthenticationCallback {
+
+    private static final long ERROR_TIMEOUT_MILLIS = 1600;
+    private static final long SUCCESS_DELAY_MILLIS = 100;
+
+    private final FingerprintManager mFingerprintManager;
+    private final SwirlView mIcon;
+    private final TextView mErrorTextView;
+    private final Callback mCallback;
+    private CancellationSignal mCancellationSignal;
+
+    private boolean mSelfCancelled;
+
+    /**
+     * Constructor for {@link FingerprintUiHelper}.
+     */
+    public FingerprintUiHelper(FingerprintManager fingerprintManager,
+                               SwirlView icon, TextView errorTextView, Callback callback) {
+        mFingerprintManager = fingerprintManager;
+        mIcon = icon;
+        mErrorTextView = errorTextView;
+        mCallback = callback;
+    }
+
+    public static FingerprintManager getManager(Context context) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            if (PermissionHelper.granted(context, Manifest.permission.USE_FINGERPRINT)) {
+                FingerprintManager manager = (FingerprintManager) context.getSystemService(Context.FINGERPRINT_SERVICE);
+                if (manager != null && manager.isHardwareDetected() && manager.hasEnrolledFingerprints()) {
+                    return manager;
+                }
+            }
+        }
+        return null;
+    }
+
+    public boolean isFingerprintAuthAvailable() {
+        // The line below prevents the false positive inspection from Android Studio
+        // noinspection ResourceType
+        return mFingerprintManager.isHardwareDetected()
+                && mFingerprintManager.hasEnrolledFingerprints();
+    }
+
+    public void startListening(FingerprintManager.CryptoObject cryptoObject) {
+        if (!isFingerprintAuthAvailable()) {
+            return;
+        }
+        mCancellationSignal = new CancellationSignal();
+        mSelfCancelled = false;
+        // The line below prevents the false positive inspection from Android Studio
+        // noinspection ResourceType
+        mFingerprintManager
+                .authenticate(cryptoObject, mCancellationSignal, 0 /* flags */, this, null);
+        mIcon.setState(SwirlView.State.ON);
+    }
+
+    public void stopListening() {
+        if (mCancellationSignal != null) {
+            mSelfCancelled = true;
+            mCancellationSignal.cancel();
+            mCancellationSignal = null;
+        }
+    }
+
+    @Override
+    public void onAuthenticationError(int errMsgId, CharSequence errString) {
+        if (!mSelfCancelled) {
+            showError(errString);
+            mIcon.postDelayed(new Runnable() {
+                @Override
+                public void run() {
+                    mCallback.onError();
+                }
+            }, ERROR_TIMEOUT_MILLIS);
+        }
+    }
+
+    @Override
+    public void onAuthenticationHelp(int helpMsgId, CharSequence helpString) {
+        showError(helpString);
+    }
+
+    @Override
+    public void onAuthenticationFailed() {
+        showError(mIcon.getResources().getString(
+                R.string.fingerprint_not_recognized));
+    }
+
+    @Override
+    public void onAuthenticationSucceeded(FingerprintManager.AuthenticationResult result) {
+        mErrorTextView.removeCallbacks(mResetErrorTextRunnable);
+        mIcon.setState(SwirlView.State.OFF);
+        mErrorTextView.setText(
+                mErrorTextView.getResources().getString(R.string.fingerprint_success));
+        mIcon.postDelayed(new Runnable() {
+            @Override
+            public void run() {
+                mCallback.onAuthenticated();
+            }
+        }, SUCCESS_DELAY_MILLIS);
+
+        // ugly hack to keep the fingerprint icon visible while also giving visual feedback of success to the user
+        mIcon.postDelayed(new Runnable() {
+            @Override
+            public void run() {
+                mIcon.setState(SwirlView.State.ON);
+            }
+        }, 500);
+    }
+
+    private void showError(CharSequence error) {
+        mIcon.setState(SwirlView.State.ERROR);
+        mErrorTextView.setText(error);
+        mErrorTextView.removeCallbacks(mResetErrorTextRunnable);
+        mErrorTextView.postDelayed(mResetErrorTextRunnable, ERROR_TIMEOUT_MILLIS);
+    }
+
+    private Runnable mResetErrorTextRunnable = new Runnable() {
+        @Override
+        public void run() {
+            mErrorTextView.setText(
+                    mErrorTextView.getResources().getString(R.string.fingerprint_hint));
+            mIcon.setState(SwirlView.State.ON);
+        }
+    };
+
+    public interface Callback {
+
+        void onAuthenticated();
+
+        void onError();
+    }
+}