universum.studios.android.recycler.helper

Class ItemDragHelper

java.lang.Object

android.support.v7.widget.RecyclerView.ItemDecoration

android.support.v7.widget.helper.ItemTouchHelper

universum.studios.android.recycler.helper.RecyclerViewItemHelper<ItemDragHelper.Interactor>

universum.studios.android.recycler.helper.ItemDragHelper

All Implemented Interfaces:

RecyclerView.OnChildAttachStateChangeListener

public final class ItemDragHelper
extends RecyclerViewItemHelper<ItemDragHelper.Interactor>

A RecyclerViewItemHelper that may be used to support drag feature for items displayed in a RecyclerView widget. Instance of this helper may be simply created via ItemDragHelper() constructor.

In order to support drag feature for a desired adapter, such adapter must implement ItemDragHelper.DragAdapter interface and needs to be attached to its corresponding RecyclerView before call to RecyclerViewItemHelper.attachToRecyclerView(RecyclerView) which will attach such adapter to the drag helper automatically. Also all ViewHolders of that adapter of which item views are desired to be dragged, must implement ItemDragHelper.DragViewHolder interface as other view holder implementations will be ignored by the ItemDragHelper API. When the ItemDragHelper.DragAdapter is properly attached, the item helper will delegate to it all drag gesture related callbacks/events whenever appropriate via the adapter's interface.

Drag Callbacks

A ItemDragHelper.OnDragListener may be registered for the helper's ItemDragHelper.Interactor via ItemDragHelper.Interactor#addOnDragListener(OnDragListener) in order to receive callbacks about started, finished or canceled drag gesture for a particular ViewHolder. If the listener is no more needed it should be unregistered via ItemDragHelper.Interactor#removeOnDragListener(OnDragListener).

Since:

1.0

Author:

Martin Albedinsky

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ItemDragHelper.DragAdapter Required interface for adapters which want to support drag feature for theirs ViewHolders.
static interface	ItemDragHelper.DragViewHolder Required interface for all ViewHolders which want to support drag feature for theirs corresponding item views.
static class	ItemDragHelper.Interactor A ItemInteractor implementation used by ItemDragHelper to handle drag gesture related callbacks and to delegate drag events to the view holder that is being dragged and also to it parent adapter in order to properly move dragged items in the adapter's data set.
static interface	ItemDragHelper.OnDragListener Listener which may be used to receive callbacks about started, finished or canceled drag gesture for a specific RecyclerView.ViewHolder instance.

Nested classes/interfaces inherited from class universum.studios.android.recycler.helper.RecyclerViewItemHelper

RecyclerViewItemHelper.Direction, RecyclerViewItemHelper.Interaction, RecyclerViewItemHelper.InteractiveViewHolder, RecyclerViewItemHelper.ItemInteractor, RecyclerViewItemHelper.Movement

Nested classes/interfaces inherited from class android.support.v7.widget.helper.ItemTouchHelper

ItemTouchHelper.Callback, ItemTouchHelper.SimpleCallback, ItemTouchHelper.ViewDropHandler

Field Summary

Fields

Modifier and Type	Field and Description
static int	INTERACTION Interaction constant specific for ItemDragHelper.
static float	MOVE_THRESHOLD Default move threshold for the drag gesture.

Fields inherited from class android.support.v7.widget.helper.ItemTouchHelper

ACTION_STATE_DRAG, ACTION_STATE_IDLE, ACTION_STATE_SWIPE, ANIMATION_TYPE_DRAG, ANIMATION_TYPE_SWIPE_CANCEL, ANIMATION_TYPE_SWIPE_SUCCESS, DOWN, END, LEFT, RIGHT, START, UP

Constructor Summary

Constructors

Constructor and Description
ItemDragHelper() Creates a new instance of ItemDragHelper.

Method Summary

Modifier and Type	Method and Description
static int	makeDragFlags(int movementFlags) Makes movement flags for the drag gesture.

Methods inherited from class universum.studios.android.recycler.helper.RecyclerViewItemHelper

attachToRecyclerView, getInteractor

Methods inherited from class android.support.v7.widget.helper.ItemTouchHelper

getItemOffsets, onChildViewAttachedToWindow, onChildViewDetachedFromWindow, onDraw, onDrawOver, startDrag, startSwipe

Methods inherited from class android.support.v7.widget.RecyclerView.ItemDecoration

getItemOffsets, onDraw, onDrawOver

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

INTERACTION

public static final int INTERACTION

Interaction constant specific for ItemDragHelper.

See Also:

ItemTouchHelper.ACTION_STATE_DRAG, Constant Field Values

MOVE_THRESHOLD

public static final float MOVE_THRESHOLD

Default move threshold for the drag gesture.

See Also:

Constant Field Values

Constructor Detail

ItemDragHelper

public ItemDragHelper()

Creates a new instance of ItemDragHelper.

Method Detail

makeDragFlags

public static int makeDragFlags(int movementFlags)

Makes movement flags for the drag gesture.

Parameters:

movementFlags - The desired movement flags. One of flags defined by @Movement annotation.

Returns:

Drag flags according to the given movement flags.

See Also:

ItemDragHelper.Callback#makeMovementFlags(int, int)