Merge "Make a11y traversal documenation clearer"

core/java/android/view/View.java

@@ -11287,26 +11287,36 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
     }
 
     /**
-     * Sets the id of a view before which this one is visited in accessibility traversal.
-     * A screen-reader must visit the content of this view before the content of the one
-     * it precedes. For example, if view B is set to be before view A, then a screen-reader
-     * will traverse the entire content of B before traversing the entire content of A,
-     * regardles of what traversal strategy it is using.
+     * Sets the id of a view that screen readers are requested to visit after this view.
+     *
      * <p>
-     * Views that do not have specified before/after relationships are traversed in order
-     * determined by the screen-reader.
-     * </p>
+     *
+     * For example, if view B should be visited before view A, with
+     * B.setAccessibilityTraversalBefore(A), this requests that screen readers visit and traverse
+     * view B before visiting view A.
+     *
      * <p>
-     * Setting that this view is before a view that is not important for accessibility
-     * or if this view is not important for accessibility will have no effect as the
-     * screen-reader is not aware of unimportant views.
-     * </p>
+     * <b>Note:</b> Views are visited in the order determined by the screen reader. Avoid
+     * explicitly manipulating focus order, as this may result in inconsistent user
+     * experiences between apps. Instead, use other semantics, such as restructuring the view
+     * hierarchy layout, to communicate order.
+     *
+     * <p>
+     * Setting this view to be after a view that is not important for accessibility,
+     * or if this view is not important for accessibility, means this method will have no effect if
+     * the service is not aware of unimportant views.
+     *
+     * <p>
+     * To avoid a risk of loops, set clear relationships between views. For example, if focus order
+     * should be B -> A, and B.setAccessibilityTraversalBefore(A), then also call
+     * A.setAccessibilityTraversalAfter(B).
      *
      * @param beforeId The id of a view this one precedes in accessibility traversal.
      *
      * @attr ref android.R.styleable#View_accessibilityTraversalBefore
      *
      * @see #setImportantForAccessibility(int)
+     * @see #setAccessibilityTraversalAfter(int)
      */
     @RemotableViewMethod
     public void setAccessibilityTraversalBefore(@IdRes int beforeId) {
@@ -11333,26 +11343,34 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
     }
 
     /**
-     * Sets the id of a view after which this one is visited in accessibility traversal.
-     * A screen-reader must visit the content of the other view before the content of this
-     * one. For example, if view B is set to be after view A, then a screen-reader
-     * will traverse the entire content of A before traversing the entire content of B,
-     * regardles of what traversal strategy it is using.
-     * <p>
-     * Views that do not have specified before/after relationships are traversed in order
-     * determined by the screen-reader.
-     * </p>
-     * <p>
-     * Setting that this view is after a view that is not important for accessibility
-     * or if this view is not important for accessibility will have no effect as the
-     * screen-reader is not aware of unimportant views.
-     * </p>
+     * Sets the id of a view that screen readers are requested to visit before this view.
      *
-     * @param afterId The id of a view this one succedees in accessibility traversal.
+     * <p>
+     * For example, if view B should be visited after A, with B.setAccessibilityTraversalAfter(A),
+     * then this requests that screen readers visit and traverse view A before visiting view B.
+     *
+     * <p>
+     * <b>Note:</b> Views are visited in the order determined by the screen reader. Avoid
+     * explicitly manipulating focus order, as this may result in inconsistent user
+     * experiences between apps. Instead, use other semantics, such as restructuring the view
+     * hierarchy layout, to communicate order.
+     *
+     * <p>
+     * Setting this view to be after a view that is not important for accessibility,
+     * or if this view is not important for accessibility, means this method will have no effect if
+     * the service is not aware of unimportant views.
+     *
+     * <p>
+     * To avoid a risk of loops, set clear relationships between views. For example, if focus order
+     * should be B -> A, and B.setAccessibilityTraversalBefore(A), then also call
+     * A.setAccessibilityTraversalAfter(B).
+     *
+     * @param afterId The id of a view this one succeeds in accessibility traversal.
      *
      * @attr ref android.R.styleable#View_accessibilityTraversalAfter
      *
      * @see #setImportantForAccessibility(int)
+     * @see #setAccessibilityTraversalBefore(int)
      */
     @RemotableViewMethod
     public void setAccessibilityTraversalAfter(@IdRes int afterId) {

core/res/res/values/attrs.xml

@@ -3030,15 +3030,15 @@
              representation this attribute can be used for providing such. -->
         <attr name="contentDescription" format="string" localization="suggested" />
 
-        <!-- Sets the id of a view before which this one is visited in accessibility traversal.
-             A screen-reader must visit the content of this view before the content of the one
-             it precedes.
+        <!-- Sets the id of a view that screen readers are requested to visit after this view.
+             Requests that a screen-reader visits the content of this view before the content of the
+             one it precedes. This does nothing if either view is not important for accessibility.
              {@see android.view.View#setAccessibilityTraversalBefore(int)} -->
         <attr name="accessibilityTraversalBefore" format="integer" />
 
-        <!-- Sets the id of a view after which this one is visited in accessibility traversal.
-             A screen-reader must visit the content of the other view before the content of
-             this one.
+        <!-- Sets the id of a view that screen readers are requested to visit before this view.
+             Requests that a screen-reader visits the content of the other view before the content
+             of this one. This does nothing if either view is not important for accessibility.
              {@see android.view.View#setAccessibilityTraversalAfter(int)} -->
         <attr name="accessibilityTraversalAfter" format="integer" />