Adding an opt-in mechanism for gesture detection in AccessibilityService.

1. An accessibility service has to explicitly opt in to be notified
   for gestures by the system. There is only one accessibility service
   that handles gestures and in case it does not handle a gesture
   the system performs default handling. This default handling ensures
   that we have gesture navigation even if no accessibility service
   would like to participate/customize the interaction model.

bug:5932640

Change-Id: Id8194293bd94097b455e9388b68134a45dc3b8fa

Author: sganov

Android.mk

@@ -61,6 +61,7 @@ LOCAL_SRC_FILES := $(filter-out \
 LOCAL_SRC_FILES += \
 	core/java/android/accessibilityservice/IAccessibilityServiceConnection.aidl \
 	core/java/android/accessibilityservice/IAccessibilityServiceClient.aidl \
+	core/java/android/accessibilityservice/IAccessibilityServiceClientCallback.aidl \
 	core/java/android/accounts/IAccountManager.aidl \
 	core/java/android/accounts/IAccountManagerResponse.aidl \
 	core/java/android/accounts/IAccountAuthenticator.aidl \

api/current.txt

@@ -294,6 +294,7 @@ package android {
     field public static final int cacheColorHint = 16843009; // 0x1010101
     field public static final int calendarViewShown = 16843596; // 0x101034c
     field public static final int calendarViewStyle = 16843613; // 0x101035d
+    field public static final int canHandleGestures = 16843699; // 0x10103b3
     field public static final int canRetrieveWindowContent = 16843653; // 0x1010385
     field public static final int candidatesTextStyleSpans = 16843312; // 0x1010230
     field public static final deprecated int capitalize = 16843113; // 0x1010169
@@ -1997,7 +1998,7 @@ package android.accessibilityservice {
     method public final android.accessibilityservice.AccessibilityServiceInfo getServiceInfo();
     method public abstract void onAccessibilityEvent(android.view.accessibility.AccessibilityEvent);
     method public final android.os.IBinder onBind(android.content.Intent);
-    method protected void onGesture(int);
+    method protected boolean onGesture(int);
     method public abstract void onInterrupt();
     method protected void onServiceConnected();
     method public final boolean performGlobalAction(int);
@@ -2020,6 +2021,8 @@ package android.accessibilityservice {
     field public static final int GESTURE_SWIPE_UP_AND_DOWN = 7; // 0x7
     field public static final int GESTURE_SWIPE_UP_AND_LEFT = 15; // 0xf
     field public static final int GESTURE_SWIPE_UP_AND_RIGHT = 16; // 0x10
+    field public static final int GESTURE_TWO_FINGER_LONG_PRESS = 20; // 0x14
+    field public static final int GESTURE_TWO_FINGER_TAP = 19; // 0x13
     field public static final int GLOBAL_ACTION_BACK = 1; // 0x1
     field public static final int GLOBAL_ACTION_HOME = 2; // 0x2
     field public static final int GLOBAL_ACTION_NOTIFICATIONS = 4; // 0x4
@@ -2033,6 +2036,7 @@ package android.accessibilityservice {
     method public int describeContents();
     method public static java.lang.String feedbackTypeToString(int);
     method public static java.lang.String flagToString(int);
+    method public boolean getCanHandleGestures();
     method public boolean getCanRetrieveWindowContent();
     method public deprecated java.lang.String getDescription();
     method public java.lang.String getId();

core/java/android/accessibilityservice/AccessibilityService.java

@@ -19,22 +19,17 @@
 import android.app.Service;
 import android.content.Context;
 import android.content.Intent;
-import android.content.res.Configuration;
 import android.os.IBinder;
 import android.os.Looper;
 import android.os.Message;
 import android.os.RemoteException;
-import android.util.LocaleUtil;
 import android.util.Log;
-import android.view.View;
 import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityInteractionClient;
 import android.view.accessibility.AccessibilityNodeInfo;
 
 import com.android.internal.os.HandlerCaller;
 
-import java.util.Locale;
-
 /**
  * An accessibility service runs in the background and receives callbacks by the system
  * when {@link AccessibilityEvent}s are fired. Such events denote some state transition
@@ -298,6 +293,16 @@ public abstract class AccessibilityService extends Service {
      */
     public static final int GESTURE_SWIPE_DOWN_AND_RIGHT = 18;
 
+    /**
+     * The user has performed a two finger tap gesture on the touch screen.
+     */
+    public static final int GESTURE_TWO_FINGER_TAP = 19;
+
+    /**
+     * The user has performed a two finger long press gesture on the touch screen.
+     */
+    public static final int GESTURE_TWO_FINGER_LONG_PRESS = 20;
+
     /**
      * The {@link Intent} that must be declared as handled by the service.
      */
@@ -342,24 +347,20 @@ public abstract class AccessibilityService extends Service {
      */
     public static final int GLOBAL_ACTION_NOTIFICATIONS = 4;
 
-    private static final int UNDEFINED = -1;
-
     private static final String LOG_TAG = "AccessibilityService";
 
     interface Callbacks {
         public void onAccessibilityEvent(AccessibilityEvent event);
         public void onInterrupt();
         public void onServiceConnected();
         public void onSetConnectionId(int connectionId);
-        public void onGesture(int gestureId);
+        public boolean onGesture(int gestureId);
     }
 
     private int mConnectionId;
 
     private AccessibilityServiceInfo mInfo;
 
-    private int mLayoutDirection;
-
     /**
      * Callback for {@link android.view.accessibility.AccessibilityEvent}s.
      *
@@ -386,95 +387,43 @@ protected void onServiceConnected() {
 
     /**
      * Called by the system when the user performs a specific gesture on the
-     * touch screen.
+     * touch screen. If the gesture is not handled in this callback the system
+     * may provide default handing. Therefore, one should return true from this
+     * function if overriding of default behavior is desired.
+     *
+     * <strong>Note:</strong> To receive gestures an accessibility service
+     *         must declare that it can handle such by specifying the
+     *         <code>&lt;{@link android.R.styleable#AccessibilityService_canHandleGestures
+     *         canHandleGestures}&gt;</code> attribute.
      *
      * @param gestureId The unique id of the performed gesture.
      *
+     * @return Whether the gesture was handled.
+     *
      * @see #GESTURE_SWIPE_UP
-     * @see #GESTURE_SWIPE_DOWN
-     * @see #GESTURE_SWIPE_LEFT
-     * @see #GESTURE_SWIPE_RIGHT
+     * @see #GESTURE_SWIPE_UP_AND_LEFT
      * @see #GESTURE_SWIPE_UP_AND_DOWN
+     * @see #GESTURE_SWIPE_UP_AND_RIGHT
+     * @see #GESTURE_SWIPE_DOWN
+     * @see #GESTURE_SWIPE_DOWN_AND_LEFT
      * @see #GESTURE_SWIPE_DOWN_AND_UP
+     * @see #GESTURE_SWIPE_DOWN_AND_RIGHT
+     * @see #GESTURE_SWIPE_LEFT
+     * @see #GESTURE_SWIPE_LEFT_AND_UP
      * @see #GESTURE_SWIPE_LEFT_AND_RIGHT
+     * @see #GESTURE_SWIPE_LEFT_AND_DOWN
+     * @see #GESTURE_SWIPE_RIGHT
+     * @see #GESTURE_SWIPE_RIGHT_AND_UP
      * @see #GESTURE_SWIPE_RIGHT_AND_LEFT
+     * @see #GESTURE_SWIPE_RIGHT_AND_DOWN
      * @see #GESTURE_CLOCKWISE_CIRCLE
      * @see #GESTURE_COUNTER_CLOCKWISE_CIRCLE
+     * @see #GESTURE_TWO_FINGER_TAP
+     * @see #GESTURE_TWO_FINGER_LONG_PRESS
      */
-    protected void onGesture(int gestureId) {
+    protected boolean onGesture(int gestureId) {
         // TODO: Describe the default gesture processing in the javaDoc once it is finalized.
-
-        // Global actions.
-        switch (gestureId) {
-            case GESTURE_SWIPE_DOWN_AND_LEFT: {
-                performGlobalAction(GLOBAL_ACTION_BACK);
-            } return;
-            case GESTURE_SWIPE_DOWN_AND_RIGHT: {
-                performGlobalAction(GLOBAL_ACTION_HOME);
-            } return;
-            case GESTURE_SWIPE_UP_AND_LEFT: {
-                performGlobalAction(GLOBAL_ACTION_RECENTS);
-            } return;
-            case GESTURE_SWIPE_UP_AND_RIGHT: {
-                performGlobalAction(GLOBAL_ACTION_NOTIFICATIONS);
-            } return;
-        }
-
-        // Cache the id to avoid locking
-        final int connectionId = mConnectionId;
-        if (connectionId == UNDEFINED) {
-            throw new IllegalStateException("AccessibilityService not connected."
-                    + " Did you receive a call of onServiceConnected()?");
-        }
-        AccessibilityNodeInfo root = getRootInActiveWindow();
-        if (root == null) {
-            return;
-        }
-
-        AccessibilityNodeInfo current = root.findFocus(AccessibilityNodeInfo.FOCUS_ACCESSIBILITY);
-        if (current == null) {
-            current = root;
-        }
-
-        // Local actions.
-        AccessibilityNodeInfo next = null;
-        switch (gestureId) {
-            case GESTURE_SWIPE_UP: {
-                next = current.focusSearch(View.ACCESSIBILITY_FOCUS_OUT);
-            } break;
-            case GESTURE_SWIPE_DOWN: {
-                next = current.focusSearch(View.ACCESSIBILITY_FOCUS_IN);
-            } break;
-            case GESTURE_SWIPE_LEFT: {
-                if (mLayoutDirection == View.LAYOUT_DIRECTION_LTR) {
-                    next = current.focusSearch(View.ACCESSIBILITY_FOCUS_BACKWARD);
-                } else { // LAYOUT_DIRECTION_RTL
-                    next = current.focusSearch(View.ACCESSIBILITY_FOCUS_FORWARD);
-                }
-            } break;
-            case GESTURE_SWIPE_RIGHT: {
-                if (mLayoutDirection == View.LAYOUT_DIRECTION_LTR) {
-                    next = current.focusSearch(View.ACCESSIBILITY_FOCUS_FORWARD);
-                } else { // LAYOUT_DIRECTION_RTL
-                    next = current.focusSearch(View.ACCESSIBILITY_FOCUS_BACKWARD);
-                }
-            } break;
-            case GESTURE_SWIPE_UP_AND_DOWN: {
-                next = current.focusSearch(View.ACCESSIBILITY_FOCUS_UP);
-            } break;
-            case GESTURE_SWIPE_DOWN_AND_UP: {
-                next = current.focusSearch(View.ACCESSIBILITY_FOCUS_DOWN);
-            } break;
-            case GESTURE_SWIPE_LEFT_AND_RIGHT: {
-                next = current.focusSearch(View.ACCESSIBILITY_FOCUS_LEFT);
-            } break;
-            case GESTURE_SWIPE_RIGHT_AND_LEFT: {
-                next = current.focusSearch(View.ACCESSIBILITY_FOCUS_RIGHT);
-            } break;
-        }
-        if (next != null && !next.equals(current)) {
-            next.performAction(AccessibilityNodeInfo.ACTION_ACCESSIBILITY_FOCUS);
-        }
+        return false;
     }
 
     /**
@@ -484,10 +433,7 @@ protected void onGesture(int gestureId) {
      * @return The root node if this service can retrieve window content.
      */
     public AccessibilityNodeInfo getRootInActiveWindow() {
-        return AccessibilityInteractionClient.getInstance()
-            .findAccessibilityNodeInfoByAccessibilityId(mConnectionId,
-                AccessibilityNodeInfo.ACTIVE_WINDOW_ID, AccessibilityNodeInfo.ROOT_NODE_ID,
-                AccessibilityNodeInfo.FLAG_PREFETCH_DESCENDANTS);
+        return AccessibilityInteractionClient.getInstance().getRootInActiveWindow(mConnectionId);
     }
 
     /**
@@ -509,7 +455,7 @@ public final boolean performGlobalAction(int action) {
             AccessibilityInteractionClient.getInstance().getConnection(mConnectionId);
         if (connection != null) {
             try {
-                return connection.perfromGlobalAction(action);
+                return connection.performGlobalAction(action);
             } catch (RemoteException re) {
                 Log.w(LOG_TAG, "Error while calling performGlobalAction", re);
             }
@@ -572,18 +518,6 @@ private void sendServiceInfo() {
         }
     }
 
-    @Override
-    public void onCreate() {
-        Locale locale = getResources().getConfiguration().locale;
-        mLayoutDirection = LocaleUtil.getLayoutDirectionFromLocale(locale);
-    }
-
-    @Override
-    public void onConfigurationChanged(Configuration configuration) {
-        super.onConfigurationChanged(configuration);
-        mLayoutDirection = LocaleUtil.getLayoutDirectionFromLocale(configuration.locale);
-    }
-
     /**
      * Implement to return the implementation of the internal accessibility
      * service interface.
@@ -612,8 +546,8 @@ public void onSetConnectionId( int connectionId) {
             }
 
             @Override
-            public void onGesture(int gestureId) {
-                AccessibilityService.this.onGesture(gestureId);
+            public boolean onGesture(int gestureId) {
+                return AccessibilityService.this.onGesture(gestureId);
             }
         });
     }
@@ -658,8 +592,10 @@ public void onAccessibilityEvent(AccessibilityEvent event) {
             mCaller.sendMessage(message);
         }
 
-        public void onGesture(int gestureId) {
-            Message message = mCaller.obtainMessageI(DO_ON_GESTURE, gestureId);
+        public void onGesture(int gestureId, IAccessibilityServiceClientCallback callback,
+                int interactionId) {
+            Message message = mCaller.obtainMessageIIO(DO_ON_GESTURE, gestureId, interactionId,
+                    callback);
             mCaller.sendMessage(message);
         }
 
@@ -692,7 +628,15 @@ public void executeMessage(Message message) {
                     return;
                 case DO_ON_GESTURE :
                     final int gestureId = message.arg1;
-                    mCallback.onGesture(gestureId);
+                    final int interactionId = message.arg2;
+                    IAccessibilityServiceClientCallback callback =
+                        (IAccessibilityServiceClientCallback) message.obj;
+                    final boolean handled = mCallback.onGesture(gestureId);
+                    try {
+                        callback.setGestureResult(gestureId, handled, interactionId);
+                    } catch (RemoteException re) {
+                        Log.e(LOG_TAG, "Error calling back with the gesture resut.", re);
+                    }
                     return;
                 default :
                     Log.w(LOG_TAG, "Unknown message type " + message.what);

core/java/android/accessibilityservice/AccessibilityServiceInfo.java

@@ -223,6 +223,11 @@ public class AccessibilityServiceInfo implements Parcelable {
      */
     private boolean mCanRetrieveWindowContent;
 
+    /**
+     * Flag whether this accessibility service can handle gestures.
+     */
+    private boolean mCanHandleGestures;
+
     /**
      * Resource id of the description of the accessibility service.
      */
@@ -303,6 +308,8 @@ public AccessibilityServiceInfo(ResolveInfo resolveInfo, Context context)
             mCanRetrieveWindowContent = asAttributes.getBoolean(
                     com.android.internal.R.styleable.AccessibilityService_canRetrieveWindowContent,
                     false);
+            mCanHandleGestures = asAttributes.getBoolean(
+                    com.android.internal.R.styleable.AccessibilityService_canHandleGestures, false);
             TypedValue peekedValue = asAttributes.peekValue(
                     com.android.internal.R.styleable.AccessibilityService_description);
             if (peekedValue != null) {
@@ -378,12 +385,24 @@ public String getSettingsActivityName() {
      *    <strong>Statically set from
      *    {@link AccessibilityService#SERVICE_META_DATA meta-data}.</strong>
      * </p>
-     * @return True window content can be retrieved.
+     * @return True if window content can be retrieved.
      */
     public boolean getCanRetrieveWindowContent() {
         return mCanRetrieveWindowContent;
     }
 
+    /**
+     * Whether this service can handle gestures.
+     * <p>
+     *    <strong>Statically set from
+     *    {@link AccessibilityService#SERVICE_META_DATA meta-data}.</strong>
+     * </p>
+     * @return True if the service can handle gestures.
+     */
+    public boolean getCanHandleGestures() {
+        return mCanHandleGestures;
+    }
+
     /**
      * Gets the non-localized description of the accessibility service.
      * <p>

core/java/android/accessibilityservice/IAccessibilityServiceClient.aidl

@@ -16,6 +16,7 @@
 
 package android.accessibilityservice;
 
+import android.accessibilityservice.IAccessibilityServiceClientCallback;
 import android.accessibilityservice.IAccessibilityServiceConnection;
 import android.view.accessibility.AccessibilityEvent;
 
@@ -32,5 +33,5 @@ import android.view.accessibility.AccessibilityEvent;
 
     void onInterrupt();
 
-    void onGesture(int gestureId);
+    void onGesture(int gesture, in IAccessibilityServiceClientCallback callback, int interactionId);
 }