AppBarLayout.Behavior

Respond to CoordinatorLayout touch events before they are dispatched to child views.

Behaviors can use this to monitor inbound touch events until one decides to intercept the rest of the event stream to take an action on its associated child view. This method will return false until it detects the proper intercept conditions, then return true once those conditions have occurred.

Once a Behavior intercepts touch events, the rest of the event stream will be sent to the onTouchEvent(CoordinatorLayout, V, MotionEvent) method.

The default implementation of this method always returns false.

Called when the parent CoordinatorLayout is about the lay out the given child view.

This method can be used to perform custom or modified layout of a child view in place of the default child layout behavior. The Behavior's implementation can delegate to the standard CoordinatorLayout measurement behavior by calling parent.onMeasureChild.

If a Behavior implements onDependentViewChanged(CoordinatorLayout, android.view.View, android.view.View) to change the position of a view in response to a dependent view changing, it should also implement onLayoutChild in such a way that respects those dependent views. onLayoutChild will always be called for a dependent view after its dependency has been laid out.

Called when the parent CoordinatorLayout is about the lay out the given child view.

This method can be used to perform custom or modified layout of a child view in place of the default child layout behavior. The Behavior's implementation can delegate to the standard CoordinatorLayout measurement behavior by calling parent.onMeasureChild.

If a Behavior implements onDependentViewChanged(CoordinatorLayout, android.view.View, android.view.View) to change the position of a view in response to a dependent view changing, it should also implement onLayoutChild in such a way that respects those dependent views. onLayoutChild will always be called for a dependent view after its dependency has been laid out.

Called when a nested scrolling child is starting a fling or an action that would be a fling.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll(CoordinatorLayout, V, View, View, int). Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onNestedFling is called when the current nested scrolling child view detects the proper conditions for a fling. It reports if the child itself consumed the fling. If it did not, the child is expected to show some sort of overscroll indication. This method should return true if it consumes the fling, so that a child that did not itself take an action in response can choose not to show an overfling indication.

Called when a nested scroll in progress is about to update, before the target has consumed any of the scrolled distance.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll(CoordinatorLayout, V, View, View, int). Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onNestedPreScroll is called each time the nested scroll is updated by the nested scrolling child, before the nested scrolling child has consumed the scroll distance itself. Each Behavior responding to the nested scroll will receive the same values. The CoordinatorLayout will report as consumed the maximum number of pixels in either direction that any Behavior responding to the nested scroll reported as consumed.

Called when a nested scroll in progress has updated and the target has scrolled or attempted to scroll.

Any Behavior associated with the direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll(CoordinatorLayout, V, View, View, int). Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onNestedScroll is called each time the nested scroll is updated by the nested scrolling child, with both consumed and unconsumed components of the scroll supplied in pixels. Each Behavior responding to the nested scroll will receive the same values.

Hook allowing a behavior to re-apply a representation of its internal state that had previously been generated by onSaveInstanceState(CoordinatorLayout, V). This function will never be called with a null state.

Hook allowing a behavior to generate a representation of its internal state that can later be used to create a new instance with that same state. This state should only contain information that is not persistent or can not be reconstructed later.

Behavior state is only saved when both the parent CoordinatorLayout and a view using this behavior have valid IDs set.

Called when a descendant of the CoordinatorLayout attempts to initiate a nested scroll.

Any Behavior associated with any direct child of the CoordinatorLayout may respond to this event and return true to indicate that the CoordinatorLayout should act as a nested scrolling parent for this scroll. Only Behaviors that return true from this method will receive subsequent nested scroll events.

Called when a nested scroll has ended.

Any Behavior associated with any direct child of the CoordinatorLayout may elect to accept the nested scroll as part of onStartNestedScroll(CoordinatorLayout, V, View, View, int). Each Behavior that returned true will receive subsequent nested scroll events for that nested scroll.

onStopNestedScroll marks the end of a single nested scroll event sequence. This is a good place to clean up any state related to the nested scroll.

Respond to CoordinatorLayout touch events after this Behavior has started intercepting them.

Behaviors may intercept touch events in order to help the CoordinatorLayout manipulate its child views. For example, a Behavior may allow a user to drag a UI pane open or closed. This method should perform actual mutations of view layout state.