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

1 files changed, 8 insertions, 5 deletions

diff --git a/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java b/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
index 6b9d95d..d61b62d 100644
--- a/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
+++ b/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
@@ -1408,6 +1408,7 @@ public class PhoneWindowManager implements WindowManagerPolicy {
             case TYPE_WALLPAPER:
             case TYPE_PRIVATE_PRESENTATION:
             case TYPE_VOICE_INTERACTION:
+            case TYPE_ACCESSIBILITY_OVERLAY:
                 // The window manager will check these.
                 break;
             case TYPE_PHONE:
@@ -1637,15 +1638,18 @@ public class PhoneWindowManager implements WindowManagerPolicy {
             // the drag layer: input for drag-and-drop is associated with this window,
             // which sits above all other focusable windows
             return 25;
-        case TYPE_SECURE_SYSTEM_OVERLAY:
+        case TYPE_ACCESSIBILITY_OVERLAY:
+            // overlay put by accessibility services to intercept user interaction
             return 26;
-        case TYPE_BOOT_PROGRESS:
+        case TYPE_SECURE_SYSTEM_OVERLAY:
             return 27;
+        case TYPE_BOOT_PROGRESS:
+            return 28;
         case TYPE_POINTER:
             // the (mouse) pointer layer
-            return 28;
-        case TYPE_HIDDEN_NAV_CONSUMER:
             return 29;
+        case TYPE_HIDDEN_NAV_CONSUMER:
+            return 30;
         }
         Log.e(TAG, "Unknown window type: " + type);
         return 2;
@@ -1949,7 +1953,6 @@ public class PhoneWindowManager implements WindowManagerPolicy {
                 }
                 mKeyguardScrim = win;
                 break;
-
         }
         return WindowManagerGlobal.ADD_OKAY;
     }