Scrolling recyclerview while dragging an item using ItemTouchHelper.Callback

Question

ItemTouchHelper.Callback call interpolateOutOfBoundsScroll by default when an item partially leaves the screen. But how can I scroll through recyclerview when an item is gradually dragged to the bottom of the screen.

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback { public static final float ALPHA_FULL = 1.0f; private final ItemTouchHelperAdapter mAdapter; private boolean isElevated; public SimpleItemTouchHelperCallback(ItemTouchHelperAdapter adapter) { mAdapter = adapter; } @Override public boolean isLongPressDragEnabled() { return true; } @Override public boolean isItemViewSwipeEnabled() { return true; } @Override public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) { // Set movement flags based on the layout manager if (recyclerView.getLayoutManager() instanceof GridLayoutManager) { final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT; final int swipeFlags = 0; return makeMovementFlags(dragFlags, swipeFlags); } else { final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN; final int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END; return makeMovementFlags(dragFlags, swipeFlags); } } @Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder source, RecyclerView.ViewHolder target) { if (source.getItemViewType() != target.getItemViewType()) { return false; } // Notify the adapter of the move mAdapter.onItemMove(source.getAdapterPosition(), target.getAdapterPosition()); return true; } @Override public void onSwiped(RecyclerView.ViewHolder viewHolder, int i) { // Notify the adapter of the dismissalmAdapter.onItemDismiss(viewHolder.getAdapterPosition()); } @Override public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) { if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) { // Fade out the view as it is swiped out of the parent bounds final float alpha = ALPHA_FULL - Math.abs(dX) / (float) viewHolder.itemView.getWidth(); viewHolder.itemView.setAlpha(alpha); viewHolder.itemView.setTranslationX(dX); } else { super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive); } } @Override public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) { // We only want the active item to change if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) { if (viewHolder instanceof ItemTouchHelperViewHolder) { Log.d("List","Selected Position "+viewHolder.getAdapterPosition()); // Let the view holder know that this item is being moved or dragged ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder; itemViewHolder.onItemSelected(); } } super.onSelectedChanged(viewHolder, actionState); } @Override public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) { super.clearView(recyclerView, viewHolder); viewHolder.itemView.setAlpha(ALPHA_FULL); if (viewHolder instanceof ItemTouchHelperViewHolder) { // Tell the view holder it time to restore the idle state ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder; itemViewHolder.onItemClear(); } } @Override public int interpolateOutOfBoundsScroll(RecyclerView recyclerView, int viewSize, int viewSizeOutOfBounds, int totalSize, long msSinceStartScroll) { return super.interpolateOutOfBoundsScroll(recyclerView, viewSize, viewSizeOutOfBounds, totalSize, msSinceStartScroll); } }