abstract class Callback
This class is the contract between ItemTouchHelper and your application. It lets you control which touch behaviors are enabled per each ViewHolder and also receive callbacks when user performs these actions.
To control which actions user can take on each view, you should override
getMovementFlags(RecyclerView, ViewHolder) and return appropriate set of direction flags. (
DOWN). You can use
makeMovementFlags(int, int) to easily construct it. Alternatively, you can use
If user drags an item, ItemTouchHelper will call
onMove(recyclerView, dragged, target). Upon receiving this callback, you should move the item from the old position (
dragged.getAdapterPosition()) to new position (
target.getAdapterPosition()) in your adapter and also call
RecyclerView.Adapter#notifyItemMoved(int, int). To control where a View can be dropped, you can override
canDropOver(RecyclerView, ViewHolder, ViewHolder). When a dragging View overlaps multiple other views, Callback chooses the closest View with which dragged View might have changed positions. Although this approach works for many use cases, if you have a custom LayoutManager, you can override
chooseDropTarget(ViewHolder, java.util.List, int, int) to select a custom drop target.
When a View is swiped, ItemTouchHelper animates it until it goes out of bounds, then calls
onSwiped(ViewHolder, int). At this point, you should update your adapter (e.g. remove the item) and call related Adapter#notify event.
This class is the contract between ItemTouchHelper and your application.
Return true if the current ViewHolder can be dropped over the the target ViewHolder.
Called by ItemTouchHelper to select a drop target from the list of ViewHolders that are under the dragged View.
Called by the ItemTouchHelper when the user interaction with an element is over and it also completed its animation.
|open static Int||
Replaces a movement direction with its relative version by taking layout direction into account.
Called by the ItemTouchHelper when user action finished on a ViewHolder and now the View will be animated to its final position.
When finding views under a dragged view, by default, ItemTouchHelper searches for views that overlap with the dragged View.
|open static ItemTouchUIUtil|
Returns the fraction that the user should move the View to be considered as it is dragged.
Should return a composite flag which defines the enabled move directions in each state (idle, swiping, dragging).