diff --git a/core/java/android/view/ViewParent.java b/core/java/android/view/ViewParent.java index 8ae69967810c3..26596d98b053e 100644 --- a/core/java/android/view/ViewParent.java +++ b/core/java/android/view/ViewParent.java @@ -269,6 +269,23 @@ public interface ViewParent { /** * Called when a child view now has or no longer is tracking transient state. * + *

"Transient state" is any state that a View might hold that is not expected to + * be reflected in the data model that the View currently presents. This state only + * affects the presentation to the user within the View itself, such as the current + * state of animations in progress or the state of a text selection operation.

+ * + *

Transient state is useful for hinting to other components of the View system + * that a particular view is tracking something complex but encapsulated. + * A ListView for example may acknowledge that list item Views + * with transient state should be preserved within their position or stable item ID + * instead of treating that view as trivially replaceable by the backing adapter. + * This allows adapter implementations to be simpler instead of needing to track + * the state of item view animations in progress such that they could be restored + * in the event of an unexpected recycling and rebinding of attached item views.

+ * + *

This method is called on a parent view when a child view or a view within + * its subtree begins or ends tracking of internal transient state.

+ * * @param child Child view whose state has changed * @param hasTransientState true if this child has transient state */