https://source.android.com/ 
/*
 * Copyright (C) 2017 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 android.accessibilityservice;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.os.Handler;
import android.os.RemoteException;
import android.util.ArrayMap;
import android.util.Log;
import com.android.internal.annotations.VisibleForTesting;


An AccessibilityService can capture gestures performed on a device's fingerprint sensor, as long as the device has a sensor capable of detecting gestures. 
 This capability must be declared by the service as AccessibilityServiceInfo.CAPABILITY_CAN_REQUEST_FINGERPRINT_GESTURES. It also requires the permission USE_FINGERPRINT.USE_FINGERPRINT. 
 Because capturing fingerprint gestures may have side effects, services with the capability only capture gestures when AccessibilityServiceInfo.FLAG_REQUEST_FINGERPRINT_GESTURES is set. 

Note: The fingerprint sensor is used for authentication in critical use cases, so services must carefully design their user's experience when performing gestures on the sensor. When the sensor is in use by an app, for example, when authenticating or enrolling a user, the sensor will not detect gestures. Services need to ensure that users understand when the sensor is in-use for authentication to prevent users from authenticating unintentionally when trying to interact with the service. They can use FingerprintGestureCallback.onGestureDetectionAvailabilityChanged(boolean) to learn when gesture detection becomes unavailable. 

Multiple accessibility services may listen for fingerprint gestures simultaneously, so services
should provide a way for the user to disable the use of this feature so multiple services don't
conflict with each other.


{@see android.hardware.fingerprint.FingerprintManager#isHardwareDetected}

/**
 * An {@link AccessibilityService} can capture gestures performed on a device's fingerprint
 * sensor, as long as the device has a sensor capable of detecting gestures.
 * <p>
 * This capability must be declared by the service as
 * {@link AccessibilityServiceInfo#CAPABILITY_CAN_REQUEST_FINGERPRINT_GESTURES}. It also requires
 * the permission {@link android.Manifest.permission#USE_FINGERPRINT}.
 * <p>
 * Because capturing fingerprint gestures may have side effects, services with the capability only
 * capture gestures when {@link AccessibilityServiceInfo#FLAG_REQUEST_FINGERPRINT_GESTURES} is set.
 * <p>
 * <strong>Note: </strong>The fingerprint sensor is used for authentication in critical use cases,
 * so services must carefully design their user's experience when performing gestures on the sensor.
 * When the sensor is in use by an app, for example, when authenticating or enrolling a user,
 * the sensor will not detect gestures. Services need to ensure that users understand when the
 * sensor is in-use for authentication to prevent users from authenticating unintentionally when
 * trying to interact with the service. They can use
 * {@link FingerprintGestureCallback#onGestureDetectionAvailabilityChanged(boolean)} to learn when
 * gesture detection becomes unavailable.
 * <p>
 * Multiple accessibility services may listen for fingerprint gestures simultaneously, so services
 * should provide a way for the user to disable the use of this feature so multiple services don't
 * conflict with each other.
 * <p>
 * {@see android.hardware.fingerprint.FingerprintManager#isHardwareDetected}
 */
public final class FingerprintGestureController {
    
Identifier for a swipe right on the fingerprint sensor 
/** Identifier for a swipe right on the fingerprint sensor */
    public static final int FINGERPRINT_GESTURE_SWIPE_RIGHT = 0x00000001;

    
Identifier for a swipe left on the fingerprint sensor 
/** Identifier for a swipe left on the fingerprint sensor */
    public static final int FINGERPRINT_GESTURE_SWIPE_LEFT = 0x00000002;

    
Identifier for a swipe up on the fingerprint sensor 
/** Identifier for a swipe up on the fingerprint sensor */
    public static final int FINGERPRINT_GESTURE_SWIPE_UP = 0x00000004;

    
Identifier for a swipe down on the fingerprint sensor 
/** Identifier for a swipe down on the fingerprint sensor */
    public static final int FINGERPRINT_GESTURE_SWIPE_DOWN = 0x00000008;

    private static final String LOG_TAG = "FingerprintGestureController";
    private final Object mLock = new Object();
    private final IAccessibilityServiceConnection mAccessibilityServiceConnection;

    private final ArrayMap<FingerprintGestureCallback, Handler> mCallbackHandlerMap =
            new ArrayMap<>(1);

    
Params:
  • connection – The connection to use for system interactions
@hide
/**
     * @param connection The connection to use for system interactions
     * @hide
     */
    @VisibleForTesting
    public FingerprintGestureController(IAccessibilityServiceConnection connection) {
        mAccessibilityServiceConnection = connection;
    }

    
Gets if the fingerprint sensor's gesture detection is available.

Returns:true if the sensor's gesture detection is available. false if it is not currently detecting gestures (for example, if it is enrolling a finger).
/**
     * Gets if the fingerprint sensor's gesture detection is available.
     *
     * @return {@code true} if the sensor's gesture detection is available. {@code false} if it is
     * not currently detecting gestures (for example, if it is enrolling a finger).
     */
    public boolean isGestureDetectionAvailable() {
        try {
            return mAccessibilityServiceConnection.isFingerprintGestureDetectionAvailable();
        } catch (RemoteException re) {
            Log.w(LOG_TAG, "Failed to check if fingerprint gestures are active", re);
            re.rethrowFromSystemServer();
            return false;
        }
    }

    
Register a callback to be informed of fingerprint sensor gesture events.

Params:
  • callback – The listener to be added.
  • handler – The handler to use for the callback. If null, callbacks will happen on the service's main thread.
/**
     * Register a callback to be informed of fingerprint sensor gesture events.
     *
     * @param callback The listener to be added.
     * @param handler The handler to use for the callback. If {@code null}, callbacks will happen
     * on the service's main thread.
     */
    public void registerFingerprintGestureCallback(
            @NonNull FingerprintGestureCallback callback, @Nullable Handler handler) {
        synchronized (mLock) {
            mCallbackHandlerMap.put(callback, handler);
        }
    }

    
Unregister a listener added with registerFingerprintGestureCallback. 
Params:
  • callback – The callback to remove. Removing a callback that was never added has no
effect.
/**
     * Unregister a listener added with {@link #registerFingerprintGestureCallback}.
     *
     * @param callback The callback to remove. Removing a callback that was never added has no
     * effect.
     */
    public void unregisterFingerprintGestureCallback(FingerprintGestureCallback callback) {
        synchronized (mLock) {
            mCallbackHandlerMap.remove(callback);
        }
    }

    
Called when gesture detection becomes active or inactive

@hide
/**
     * Called when gesture detection becomes active or inactive
     * @hide
     */
    public void onGestureDetectionActiveChanged(boolean active) {
        final ArrayMap<FingerprintGestureCallback, Handler> handlerMap;
        synchronized (mLock) {
            handlerMap = new ArrayMap<>(mCallbackHandlerMap);
        }
        int numListeners = handlerMap.size();
        for (int i = 0; i < numListeners; i++) {
            FingerprintGestureCallback callback = handlerMap.keyAt(i);
            Handler handler = handlerMap.valueAt(i);
            if (handler != null) {
                handler.post(() -> callback.onGestureDetectionAvailabilityChanged(active));
            } else {
                callback.onGestureDetectionAvailabilityChanged(active);
            }
        }
    }

    
Called when gesture is detected.

@hide
/**
     * Called when gesture is detected.
     * @hide
     */
    public void onGesture(int gesture) {
        final ArrayMap<FingerprintGestureCallback, Handler> handlerMap;
        synchronized (mLock) {
            handlerMap = new ArrayMap<>(mCallbackHandlerMap);
        }
        int numListeners = handlerMap.size();
        for (int i = 0; i < numListeners; i++) {
            FingerprintGestureCallback callback = handlerMap.keyAt(i);
            Handler handler = handlerMap.valueAt(i);
            if (handler != null) {
                handler.post(() -> callback.onGestureDetected(gesture));
            } else {
                callback.onGestureDetected(gesture);
            }
        }
    }

    
Class that is called back when fingerprint gestures are being used for accessibility.

/**
     * Class that is called back when fingerprint gestures are being used for accessibility.
     */
    public abstract static class FingerprintGestureCallback {
        
Called when the fingerprint sensor's gesture detection becomes available or unavailable.

Params:
  • available – Whether or not the sensor's gesture detection is now available.
/**
         * Called when the fingerprint sensor's gesture detection becomes available or unavailable.
         *
         * @param available Whether or not the sensor's gesture detection is now available.
         */
        public void onGestureDetectionAvailabilityChanged(boolean available) {}

        
Called when the fingerprint sensor detects gestures.

Params:
/**
         * Called when the fingerprint sensor detects gestures.
         *
         * @param gesture The id of the gesture that was detected. For example,
         * {@link #FINGERPRINT_GESTURE_SWIPE_RIGHT}.
         */
        public void onGestureDetected(int gesture) {}
    }
}