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Adding accessibility events for touch and gesture detection states.
1. Currently the system fires accessibility events to announce the start and end of a touch exploration gesture. However, such a gesture starts after we have decided that the user is not performing a gesture which is achieved by measuring speed of movement during a threshold distance. This allows an accessibility service to provide some feedback to the user so he knows that he is touch exploring. This change adds event types for the first and last touches of the user. Note that the first touch does not conincide with the start of a touch exploration gesture since we need a time or distance to pass before we know whether the user explores or gestures. However, it is very useful for an accessibility service to know when the user starts to interact with the touch screen so it can turn the speech off, to name one compelling use case. This change also provides event types for the start and end of gesture detection. If the user has moved over the threshold with a speed greater than X, then the system detects gestures. It is useful for an accessibility service to know the begin and end of gesture detection so it can provide given feedback type for such a gesture, say it may produce haptic feedback or sound that differs for the one for touch exploration. The main benefit of announcing these new events is that an accessibility service can provide feedback for each touch state allowing the user to always know what he is doing. bug:7166935 Change-Id: I26270d774cc059cb921d6a4254bc0aab0530c1dd
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‎api/current.txt‎

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@@ -26054,9 +26054,13 @@ package android.view.accessibility {
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field public static final deprecated int MAX_TEXT_LENGTH = 500; // 0x1f4
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field public static final int TYPES_ALL_MASK = -1; // 0xffffffff
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field public static final int TYPE_ANNOUNCEMENT = 16384; // 0x4000
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field public static final int TYPE_GESTURE_DETECTION_END = 524288; // 0x80000
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field public static final int TYPE_GESTURE_DETECTION_START = 262144; // 0x40000
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field public static final int TYPE_NOTIFICATION_STATE_CHANGED = 64; // 0x40
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field public static final int TYPE_TOUCH_EXPLORATION_GESTURE_END = 1024; // 0x400
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field public static final int TYPE_TOUCH_EXPLORATION_GESTURE_START = 512; // 0x200
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field public static final int TYPE_TOUCH_INTERACTION_END = 2097152; // 0x200000
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field public static final int TYPE_TOUCH_INTERACTION_START = 1048576; // 0x100000
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field public static final int TYPE_VIEW_ACCESSIBILITY_FOCUSED = 32768; // 0x8000
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field public static final int TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED = 65536; // 0x10000
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field public static final int TYPE_VIEW_CLICKED = 1; // 0x1

‎core/java/android/view/accessibility/AccessibilityEvent.java‎

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@@ -424,22 +424,37 @@
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* </ul>
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* </p>
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* <p>
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* <b>Touch interaction start</b> - represents the event of starting a touch
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* interaction, which is the user starts touching the screen.</br>
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* <em>Type:</em> {@link #TYPE_TOUCH_INTERACTION_START}</br>
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* <em>Properties:</em></br>
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* <ul>
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* <li>{@link #getEventType()} - The type of the event.</li>
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* </ul>
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* <em>Note:</em> This event is fired only by the system and is not passed to the
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* view tree to be populated.</br>
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* </p>
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* <p>
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* <b>Touch interaction end</b> - represents the event of ending a touch
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* interaction, which is the user stops touching the screen.</br>
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* <em>Type:</em> {@link #TYPE_TOUCH_INTERACTION_END}</br>
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* <em>Properties:</em></br>
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* <ul>
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* <li>{@link #getEventType()} - The type of the event.</li>
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* </ul>
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* <em>Note:</em> This event is fired only by the system and is not passed to the
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* view tree to be populated.</br>
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* </p>
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* <p>
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* <b>Touch exploration gesture start</b> - represents the event of starting a touch
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* exploring gesture.</br>
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* <em>Type:</em> {@link #TYPE_TOUCH_EXPLORATION_GESTURE_START}</br>
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* <em>Properties:</em></br>
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* <ul>
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* <li>{@link #getEventType()} - The type of the event.</li>
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* </ul>
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* <em>Note:</em> This event type is not dispatched to descendants though
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* {@link android.view.View#dispatchPopulateAccessibilityEvent(AccessibilityEvent)
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* View.dispatchPopulateAccessibilityEvent(AccessibilityEvent)}, hence the event
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* source {@link android.view.View} and the sub-tree rooted at it will not receive
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* calls to {@link android.view.View#onPopulateAccessibilityEvent(AccessibilityEvent)
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* View.onPopulateAccessibilityEvent(AccessibilityEvent)}. The preferred way to add
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* text content to such events is by setting the
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* {@link android.R.styleable#View_contentDescription contentDescription} of the source
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* view.</br>
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* <em>Note:</em> This event is fired only by the system and is not passed to the
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* view tree to be populated.</br>
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* </p>
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* <p>
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* <b>Touch exploration gesture end</b> - represents the event of ending a touch
@@ -449,15 +464,30 @@
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* <ul>
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* <li>{@link #getEventType()} - The type of the event.</li>
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* </ul>
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* <em>Note:</em> This event type is not dispatched to descendants though
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* {@link android.view.View#dispatchPopulateAccessibilityEvent(AccessibilityEvent)
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* View.dispatchPopulateAccessibilityEvent(AccessibilityEvent)}, hence the event
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* source {@link android.view.View} and the sub-tree rooted at it will not receive
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* calls to {@link android.view.View#onPopulateAccessibilityEvent(AccessibilityEvent)
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* View.onPopulateAccessibilityEvent(AccessibilityEvent)}. The preferred way to add
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* text content to such events is by setting the
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* {@link android.R.styleable#View_contentDescription contentDescription} of the source
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* view.</br>
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* <em>Note:</em> This event is fired only by the system and is not passed to the
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* view tree to be populated.</br>
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* </p>
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* <p>
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* <b>Touch gesture detection start</b> - represents the event of starting a user
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* gesture detection.</br>
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* <em>Type:</em> {@link #TYPE_GESTURE_DETECTION_START}</br>
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* <em>Properties:</em></br>
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* <ul>
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* <li>{@link #getEventType()} - The type of the event.</li>
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* </ul>
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* <em>Note:</em> This event is fired only by the system and is not passed to the
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* view tree to be populated.</br>
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* </p>
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* <p>
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* <b>Touch gesture detection end</b> - represents the event of ending a user
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* gesture detection.</br>
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* <em>Type:</em> {@link #TYPE_GESTURE_DETECTION_END}</br>
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* <em>Properties:</em></br>
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* <ul>
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* <li>{@link #getEventType()} - The type of the event.</li>
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* </ul>
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* <em>Note:</em> This event is fired only by the system and is not passed to the
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* view tree to be populated.</br>
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* </p>
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* <p>
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* <b>MISCELLANEOUS TYPES</b></br>
@@ -609,6 +639,26 @@ public final class AccessibilityEvent extends AccessibilityRecord implements Par
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*/
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public static final int TYPE_VIEW_TEXT_TRAVERSED_AT_MOVEMENT_GRANULARITY = 0x00020000;
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/**
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* Represents the event of beginning gesture detection.
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*/
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public static final int TYPE_GESTURE_DETECTION_START = 0x00040000;
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/**
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* Represents the event of ending gesture detection.
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*/
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public static final int TYPE_GESTURE_DETECTION_END = 0x00080000;
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/**
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* Represents the event of the user starting to touch the screen.
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*/
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public static final int TYPE_TOUCH_INTERACTION_START = 0x00100000;
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/**
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* Represents the event of the user ending to touch the screen.
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*/
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public static final int TYPE_TOUCH_INTERACTION_END = 0x00200000;
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/**
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* Mask for {@link AccessibilityEvent} all types.
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*
@@ -628,6 +678,10 @@ public final class AccessibilityEvent extends AccessibilityRecord implements Par
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* @see #TYPE_VIEW_TEXT_SELECTION_CHANGED
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* @see #TYPE_ANNOUNCEMENT
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* @see #TYPE_VIEW_TEXT_TRAVERSED_AT_MOVEMENT_GRANULARITY
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* @see #TYPE_GESTURE_DETECTION_START
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* @see #TYPE_GESTURE_DETECTION_END
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* @see #TYPE_TOUCH_INTERACTION_START
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* @see #TYPE_TOUCH_INTERACTION_END
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*/
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public static final int TYPES_ALL_MASK = 0xFFFFFFFF;
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@@ -1120,6 +1174,14 @@ public static String eventTypeToString(int eventType) {
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return "TYPE_VIEW_ACCESSIBILITY_FOCUS_CLEARED";
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case TYPE_VIEW_TEXT_TRAVERSED_AT_MOVEMENT_GRANULARITY:
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return "TYPE_CURRENT_AT_GRANULARITY_MOVEMENT_CHANGED";
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case TYPE_GESTURE_DETECTION_START:
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return "TYPE_GESTURE_DETECTION_START";
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case TYPE_GESTURE_DETECTION_END:
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return "TYPE_GESTURE_DETECTION_END";
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case TYPE_TOUCH_INTERACTION_START:
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return "TYPE_TOUCH_INTERACTION_START";
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case TYPE_TOUCH_INTERACTION_END:
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return "TYPE_TOUCH_INTERACTION_END";
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default:
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return null;
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}

‎services/java/com/android/server/accessibility/AccessibilityManagerService.java‎

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@@ -173,10 +173,6 @@ public class AccessibilityManagerService extends IAccessibilityManager.Stub {
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private Service mQueryBridge;
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private boolean mTouchExplorationGestureEnded;
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private boolean mTouchExplorationGestureStarted;
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private AlertDialog mEnableTouchExplorationDialog;
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/**
@@ -400,18 +396,6 @@ public void binderDied() {
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}
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public boolean sendAccessibilityEvent(AccessibilityEvent event) {
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final int eventType = event.getEventType();
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// The event for gesture start should be strictly before the
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// first hover enter event for the gesture.
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if (eventType == AccessibilityEvent.TYPE_VIEW_HOVER_ENTER
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&& mTouchExplorationGestureStarted) {
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mTouchExplorationGestureStarted = false;
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AccessibilityEvent gestureStartEvent = AccessibilityEvent.obtain(
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AccessibilityEvent.TYPE_TOUCH_EXPLORATION_GESTURE_START);
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sendAccessibilityEvent(gestureStartEvent);
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}
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synchronized (mLock) {
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if (mSecurityPolicy.canDispatchAccessibilityEvent(event)) {
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mSecurityPolicy.updateActiveWindowAndEventSourceLocked(event);
@@ -421,22 +405,10 @@ public boolean sendAccessibilityEvent(AccessibilityEvent event) {
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if (mHasInputFilter && mInputFilter != null) {
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mMainHandler.obtainMessage(MSG_SEND_ACCESSIBILITY_EVENT_TO_INPUT_FILTER,
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AccessibilityEvent.obtain(event)).sendToTarget();
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}
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event.recycle();
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mHandledFeedbackTypes = 0;
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}
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// The event for gesture end should be strictly after the
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// last hover exit event for the gesture.
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if (eventType == AccessibilityEvent.TYPE_VIEW_HOVER_EXIT
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&& mTouchExplorationGestureEnded) {
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mTouchExplorationGestureEnded = false;
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AccessibilityEvent gestureEndEvent = AccessibilityEvent.obtain(
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AccessibilityEvent.TYPE_TOUCH_EXPLORATION_GESTURE_END);
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sendAccessibilityEvent(gestureEndEvent);
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}
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return (OWN_PROCESS_ID != Binder.getCallingPid());
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}
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@@ -628,14 +600,6 @@ private Service getQueryBridge() {
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return mQueryBridge;
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}
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public void touchExplorationGestureEnded() {
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mTouchExplorationGestureEnded = true;
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}
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public void touchExplorationGestureStarted() {
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mTouchExplorationGestureStarted = true;
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}
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private boolean notifyGestureLocked(int gestureId, boolean isDefault) {
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// TODO: Now we are giving the gestures to the last enabled
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// service that can handle them which is the last one

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