APIs for an accessibility service to put interaction tracking overlays.

An accessibility service may register to observe the interactive windows
on the primary display. These windows are the one that has input focus and
ones a sighted user can touch. It is sometimes beneficial for an
accessibility service to overlay a window to intercept user interaction
and based on that introspect and perform an action on the windows that
are on the screen. This is problematic as overlaying a full screen window
that is touchable prevents the accessibility service to introspect the
content under this window.

This change adds a special type of window that only an accessibility service
can place which does not affect what an accessibility service can "see" on
the screen. Hence, even putting such a window full screen the service will
be able to interact with the other interactive windows it covers.

Change-Id: I053ccc3a5c6360a98dc40bdb172b54dab35d8b31

2 files changed, 87 insertions, 11 deletions

diff --git a/core/java/android/accessibilityservice/AccessibilityService.java b/core/java/android/accessibilityservice/AccessibilityService.java
index 13ceb4a..1e1b33f 100644
--- a/core/java/android/accessibilityservice/AccessibilityService.java
+++ b/core/java/android/accessibilityservice/AccessibilityService.java
@@ -24,13 +24,18 @@ import android.os.Looper;
 import android.os.Message;
 import android.os.RemoteException;
 import android.util.Log;
+import android.view.Display;
 import android.view.KeyEvent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.WindowManager;
 import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityInteractionClient;
 import android.view.accessibility.AccessibilityNodeInfo;
 import android.view.accessibility.AccessibilityWindowInfo;
 
 import com.android.internal.os.HandlerCaller;
+import com.android.internal.os.SomeArgs;
 
 import java.util.List;
 
@@ -366,7 +371,7 @@ public abstract class AccessibilityService extends Service {
         public void onAccessibilityEvent(AccessibilityEvent event);
         public void onInterrupt();
         public void onServiceConnected();
-        public void onSetConnectionId(int connectionId);
+        public void init(int connectionId, IBinder windowToken);
         public boolean onGesture(int gestureId);
         public boolean onKeyEvent(KeyEvent event);
     }
@@ -375,6 +380,10 @@ public abstract class AccessibilityService extends Service {
 
     private AccessibilityServiceInfo mInfo;
 
+    private IBinder mWindowToken;
+
+    private WindowManager mWindowManager;
+
     /**
      * Callback for {@link android.view.accessibility.AccessibilityEvent}s.
      *
@@ -611,6 +620,18 @@ public abstract class AccessibilityService extends Service {
         }
     }
 
+    @Override
+    public Object getSystemService(String name) {
+        if (Context.WINDOW_SERVICE.equals(name)) {
+            if (mWindowManager == null) {
+                WindowManager wrapped = (WindowManager) super.getSystemService(name);
+                mWindowManager = new LocalWindowManager(wrapped);
+            }
+            return mWindowManager;
+        }
+        return super.getSystemService(name);
+    }
+
     /**
      * Implement to return the implementation of the internal accessibility
      * service interface.
@@ -634,8 +655,9 @@ public abstract class AccessibilityService extends Service {
             }
 
             @Override
-            public void onSetConnectionId( int connectionId) {
+            public void init(int connectionId, IBinder windowToken) {
                 mConnectionId = connectionId;
+                mWindowToken = windowToken;
             }
 
             @Override
@@ -658,7 +680,7 @@ public abstract class AccessibilityService extends Service {
      */
     public static class IAccessibilityServiceClientWrapper extends IAccessibilityServiceClient.Stub
             implements HandlerCaller.Callback {
-        private static final int DO_SET_SET_CONNECTION = 1;
+        private static final int DO_INIT = 1;
         private static final int DO_ON_INTERRUPT = 2;
         private static final int DO_ON_ACCESSIBILITY_EVENT = 3;
         private static final int DO_ON_GESTURE = 4;
@@ -677,9 +699,10 @@ public abstract class AccessibilityService extends Service {
             mCaller = new HandlerCaller(context, looper, this, true /*asyncHandler*/);
         }
 
-        public void setConnection(IAccessibilityServiceConnection connection, int connectionId) {
-            Message message = mCaller.obtainMessageIO(DO_SET_SET_CONNECTION, connectionId,
-                    connection);
+        public void init(IAccessibilityServiceConnection connection, int connectionId,
+                IBinder windowToken) {
+            Message message = mCaller.obtainMessageIOO(DO_INIT, connectionId,
+                    connection, windowToken);
             mCaller.sendMessage(message);
         }
 
@@ -730,20 +753,24 @@ public abstract class AccessibilityService extends Service {
                     mCallback.onInterrupt();
                 } return;
 
-                case DO_SET_SET_CONNECTION: {
+                case DO_INIT: {
                     mConnectionId = message.arg1;
+                    SomeArgs args = (SomeArgs) message.obj;
                     IAccessibilityServiceConnection connection =
-                        (IAccessibilityServiceConnection) message.obj;
+                            (IAccessibilityServiceConnection) args.arg1;
+                    IBinder windowToken = (IBinder) args.arg2;
+                    args.recycle();
                     if (connection != null) {
                         AccessibilityInteractionClient.getInstance().addConnection(mConnectionId,
                                 connection);
-                        mCallback.onSetConnectionId(mConnectionId);
+                        mCallback.init(mConnectionId, windowToken);
                         mCallback.onServiceConnected();
                     } else {
                         AccessibilityInteractionClient.getInstance().removeConnection(
                                 mConnectionId);
+                        mConnectionId = AccessibilityInteractionClient.NO_ID;
                         AccessibilityInteractionClient.getInstance().clearCache();
-                        mCallback.onSetConnectionId(AccessibilityInteractionClient.NO_ID);
+                        mCallback.init(AccessibilityInteractionClient.NO_ID, null);
                     }
                 } return;
 
@@ -785,4 +812,53 @@ public abstract class AccessibilityService extends Service {
             }
         }
     }
+
+    private class LocalWindowManager implements WindowManager {
+        private final WindowManager mImpl;
+
+        private LocalWindowManager(WindowManager impl) {
+            mImpl = impl;
+        }
+
+        @Override
+        public Display getDefaultDisplay() {
+            return mImpl.getDefaultDisplay();
+        }
+
+        @Override
+        public void addView(View view, ViewGroup.LayoutParams params) {
+            if (!(params instanceof WindowManager.LayoutParams)) {
+                throw new IllegalArgumentException("Params must be WindowManager.LayoutParams");
+            }
+            WindowManager.LayoutParams windowParams = (WindowManager.LayoutParams) params;
+            if (windowParams.type == LayoutParams.TYPE_ACCESSIBILITY_OVERLAY
+                    && windowParams.token == null) {
+                windowParams.token = mWindowToken;
+            }
+            mImpl.addView(view, params);
+        }
+
+        @Override
+        public void updateViewLayout(View view, ViewGroup.LayoutParams params) {
+            if (!(params instanceof WindowManager.LayoutParams)) {
+                throw new IllegalArgumentException("Params must be WindowManager.LayoutParams");
+            }
+            WindowManager.LayoutParams windowParams = (WindowManager.LayoutParams) params;
+            if (windowParams.type == LayoutParams.TYPE_ACCESSIBILITY_OVERLAY
+                    && windowParams.token == null) {
+                windowParams.token = mWindowToken;
+            }
+            mImpl.updateViewLayout(view, params);
+        }
+
+        @Override
+        public void removeViewImmediate(View view) {
+            mImpl.removeViewImmediate(view);
+        }
+
+        @Override
+        public void removeView(View view) {
+            mImpl.removeView(view);
+        }
+    }
 }
diff --git a/core/java/android/accessibilityservice/IAccessibilityServiceClient.aidl b/core/java/android/accessibilityservice/IAccessibilityServiceClient.aidl
index 6ce0219..8b503dd 100644
--- a/core/java/android/accessibilityservice/IAccessibilityServiceClient.aidl
+++ b/core/java/android/accessibilityservice/IAccessibilityServiceClient.aidl
@@ -28,7 +28,7 @@ import android.view.KeyEvent;
  */
  oneway interface IAccessibilityServiceClient {
 
-    void setConnection(in IAccessibilityServiceConnection connection, int connectionId);
+    void init(in IAccessibilityServiceConnection connection, int connectionId, IBinder windowToken);
 
     void onAccessibilityEvent(in AccessibilityEvent event);