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, 26 insertions, 9 deletions

diff --git a/core/java/android/view/accessibility/AccessibilityWindowInfo.java b/core/java/android/view/accessibility/AccessibilityWindowInfo.java
index ad55f5f..e1942be 100644
--- a/core/java/android/view/accessibility/AccessibilityWindowInfo.java
+++ b/core/java/android/view/accessibility/AccessibilityWindowInfo.java
@@ -51,11 +51,24 @@ public final class AccessibilityWindowInfo implements Parcelable {
      */
     public static final int TYPE_SYSTEM = 3;
 
+    /**
+     * Window type: Windows that are overlaid <em>only</em> by an {@link
+     * android.accessibilityservice.AccessibilityService} for interception of
+     * user interactions without changing the windows an accessibility service
+     * can introspect. In particular, an accessibility service can introspect
+     * only windows that a sighted user can interact with which they can touch
+     * these windows or can type into these windows. For example, if there
+     * is a full screen accessibility overlay that is touchable, the windows
+     * below it will be introspectable by an accessibility service regardless
+     * they are covered by a touchable window.
+     */
+    public static final int TYPE_ACCESSIBILITY_OVERLAY = 4;
+
     private static final int UNDEFINED = -1;
 
     private static final int BOOLEAN_PROPERTY_ACTIVE = 1 << 0;
     private static final int BOOLEAN_PROPERTY_FOCUSED = 1 << 1;
-    private static final int BOOLEAN_PROPERTY_ACCESSIBLITY_FOCUSED = 1 << 2;
+    private static final int BOOLEAN_PROPERTY_ACCESSIBILITY_FOCUSED = 1 << 2;
 
     // Housekeeping.
     private static final int MAX_POOL_SIZE = 10;
@@ -85,6 +98,7 @@ public final class AccessibilityWindowInfo implements Parcelable {
      * @see #TYPE_APPLICATION
      * @see #TYPE_INPUT_METHOD
      * @see #TYPE_SYSTEM
+     * @see #TYPE_ACCESSIBILITY_OVERLAY
      */
     public int getType() {
         return mType;
@@ -93,7 +107,7 @@ public final class AccessibilityWindowInfo implements Parcelable {
     /**
      * Sets the type of the window.
      *
-     * @param The type
+     * @param type The type
      *
      * @hide
      */
@@ -115,7 +129,7 @@ public final class AccessibilityWindowInfo implements Parcelable {
      * Sets the layer which determines the Z-order of the window. Windows
      * with greater layer appear on top of windows with lesser layer.
      *
-     * @param The window layer.
+     * @param layer The window layer.
      *
      * @hide
      */
@@ -174,7 +188,7 @@ public final class AccessibilityWindowInfo implements Parcelable {
     /**
      * Sets the unique window id.
      *
-     * @param windowId The window id.
+     * @param id The window id.
      *
      * @hide
      */
@@ -230,7 +244,7 @@ public final class AccessibilityWindowInfo implements Parcelable {
      * the user is currently touching or the window has input focus
      * and the user is not touching any window.
      *
-     * @param Whether this is the active window.
+     * @param active Whether this is the active window.
      *
      * @hide
      */
@@ -250,7 +264,7 @@ public final class AccessibilityWindowInfo implements Parcelable {
     /**
      * Sets if this window has input focus.
      *
-     * @param Whether has input focus.
+     * @param focused Whether has input focus.
      *
      * @hide
      */
@@ -264,18 +278,18 @@ public final class AccessibilityWindowInfo implements Parcelable {
      * @return Whether has accessibility focus.
      */
     public boolean isAccessibilityFocused() {
-        return getBooleanProperty(BOOLEAN_PROPERTY_ACCESSIBLITY_FOCUSED);
+        return getBooleanProperty(BOOLEAN_PROPERTY_ACCESSIBILITY_FOCUSED);
     }
 
     /**
      * Sets if this window has accessibility focus.
      *
-     * @param Whether has accessibility focus.
+     * @param focused Whether has accessibility focus.
      *
      * @hide
      */
     public void setAccessibilityFocused(boolean focused) {
-        setBooleanProperty(BOOLEAN_PROPERTY_ACCESSIBLITY_FOCUSED, focused);
+        setBooleanProperty(BOOLEAN_PROPERTY_ACCESSIBILITY_FOCUSED, focused);
     }
 
     /**
@@ -534,6 +548,9 @@ public final class AccessibilityWindowInfo implements Parcelable {
             case TYPE_SYSTEM: {
                 return "TYPE_SYSTEM";
             }
+            case TYPE_ACCESSIBILITY_OVERLAY: {
+                return "TYPE_ACCESSIBILITY_OVERLAY";
+            }
             default:
                 return "<UNKNOWN>";
         }