5.x | Drag&Drop and Swipe

In this page

• Activation
• Custom activation per Item Type
• Behaviors in action
• Dragging an item
  • Long press
  • Handle View
• Swiping the front view
• Callbacks

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Activation

//First, assign the adapter to the RecyclerView
mRecyclerView.setAdapter(mAdapter);

//Enable long press drag
mAdapter.setLongPressDragEnabled(true);

//Enable handle drag
mAdapter.setHandleDragEnabled(true);

//Enable Swipe-To-Dismiss
mAdapter.setSwipeEnabled(true);

Custom activation per Item Type (from beta 7)

There are 2 ways to customize if a specific item type is Draggable or Swipeable:

• Using methods from item interface IFlexible or AbstractFlexibleItem: call setDraggable() and setSwipeable(), in the constructor or in the binding depends by your use case.
• Alternatively, override the 2 methods isDraggable(), isSwipeable() inside the implementation of the FlexibleViewHolder to return always true.

By default items are NOT Draggable nor Swipeable.

Behaviors in action (in FlexibleViewHolder)

Override the following methods from FlexibleViewHolder class (displaying default values):

/**
 * Checks if the instance of the item represented by this ViewHolder is Draggable.
 */
@Override
public boolean isDraggable() {
	IFlexible item = mAdapter.getItem(getFlexibleAdapterPosition());
	return item != null && item.isDraggable();
}

/**
 * Checks if the instance of the item represented by this ViewHolder is Swipeable.
 */
@Override
public boolean isSwipeable() {
	IFlexible item = mAdapter.getItem(getFlexibleAdapterPosition());
	return item != null && item.isSwipeable();
}

/**
 * Allows to set elevation while the view is activated.
 * Override to return desired value of elevation on this itemView.
 *
 * @return never elevate, returns 0dp if not overridden
 */
public float getActivationElevation() {
	return 0f;
}

/**
 * Allows to activate the itemView when Swipe event occurs.
 * This method returns always false; Extend with "return true" to Not expand or
 * collapse this ItemView onClick events.
 *
 * @return always false, if not overridden
 */
protected boolean shouldActivateViewWhileSwiping() {
	return false;
}

/**
 * Allows to add and keep item selection if ActionMode is active.
 * This method returns always false; Extend with "return true" to add item to the
 * ActionMode count.
 *
 * @return always false, if not overridden
 */
protected boolean shouldAddSelectionInActionMode() {
	return false;
}

Dragging an item

Long press

If the instance of the item is compliant with the Draggable status, it is sufficient to call the method:

mAdapter.setLongPressDragEnabled(true);

Everytime user drags an item, the following chain of methods are called:

/**
 * Evaluate if positions are compatible for swapping.
 */
@Override
public boolean shouldMove(int fromPosition, int toPosition) {
	//Always allow swapping
	return true;
}
/**
 * Called when an item has been dragged far enough to trigger a move. This is
 * called every time an item is shifted, and NOT at the end of a "drop" event!!!
 */
@Override
@CallSuper
public boolean onItemMove(int fromPosition, int toPosition) {
	swapItems(fromPosition, toPosition);
	//After the swap, delegate further actions to the user
	if (mItemMoveListener != null) {
		mItemMoveListener.onItemMove(fromPosition, toPosition);
	}
	return true;
}
/**
 * Swaps the elements of list at indices fromPosition and toPosition and notify
 * the change. Selection of swiped elements is automatically updated.
 */
public void swapItems(int fromPosition, int toPosition) {
	//This implementation takes care automatically:
	//- The Header Linkage and notification of the items involved
	//  (for more details, see Headers And Section wiki page);
	//- Collapse of expanded expandable;
	//- Active selection swapping.
}

Handle View

This functionality is compatible with Long Press Drag, both can be used simultaneously.
The Handle View is created in the ViewHolder:

static final class ViewHolder extends FlexibleViewHolder {
	...
	public ImageView mHandleView;

	public ViewHolder(View view, FlexibleAdapter adapter) {
		super(view, adapter);
		//I left this part of the code free to be customized by the developer
		//So he can decide what to do in case the functionality is
		//enabled/disabled at runtime
		this.mHandleView = (ImageView) view.findViewById(R.id.row_handle);
		//Until the method is final, the logic inside the next method
		//can be inserted here.
		setDragHandleView(mHandleView);
	}

	//In beta7 this method is still declared final and cannot be overridden.
	//With next release it will become available to be customized.
	@Override
	protected void setDragHandleView(@NonNull View view) {
		if (mAdapter.isHandleDragEnabled()) {
			view.setVisibility(View.VISIBLE);
			super.setDragHandleView(view);
		} else {
			view.setVisibility(View.GONE);
		}
	}
}

Limitations

SwipeRefreshLayout is not compatible with dragging, at the bottom of the page the resolution is provided.

Swiping the front view

Different background can be shown by overriding the following methods of FlexibleViewHolder class:

//Inner class
static final class ViewHolder extends FlexibleViewHolder {
	...
	private View frontView;
	private View rearLeftView;
	private View rearRightView;
	
	public ViewHolder(View view, FlexibleAdapter adapter) {
		super(view, adapter);
		...
		this.frontView = view.findViewById(R.id.front_view);
		this.rearLeftView = view.findViewById(R.id.rear_left_view);
		this.rearRightView = view.findViewById(R.id.rear_right_view);
	}
	
	@Override
	public View getFrontView() {
		return frontView;//default itemView
	}
	
	@Override
	public View getRearLeftView() {
		return rearLeftView;//default null
	}
	
	@Override
	public View getRearRightView() {
		return rearRightView;//default null
	}
}

XML Layout:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
	xmlns:android="http://schemas.android.com/apk/res/android"
	xmlns:tools="http://schemas.android.com/tools"
	android:layout_width="match_parent"
	android:layout_height="?android:attr/listPreferredItemHeightLarge">

	<RelativeLayout
		android:id="@+id/front_view"
		.../>

	<RelativeLayout
		android:id="@+id/rear_left_view"
		.../>

	<RelativeLayout
		android:id="@+id/rear_right_view"
		.../>

</FrameLayout>

Limitations

Only Swipe-To-Dismiss is supported. Item half swipe cannot be implemented due to how the android.support.v7.widget.helper.ItemTouchHelper is done. Half swipe can be done with others means, please see issues #98 and #100. See also commits of Apr 25, 2016.

When front view is swiped left or right, you should do/show something. A nice example is Gmail app, study it for precise behaviors.

Callbacks (from beta7)

The Adapter method getItemTouchHelperCallback() returns the instance of the Callback already initialized by the Adapter so you can add more customization for dragging and swiping, such as SwipeFlags LEFT RIGHT UP `DOWN and SwipeThreshold limits.

There are 2 methods already implemented from the internal interface ViewHolderCallback to handle the activation/selection in combination with the ActionMode. You can override if you want more customization.

public void onActionStateChanged(int position, int actionState);
public void onItemReleased(int position);

• onActionStateChanged() is called every time an event of Drag or Swipe change state. When you have the SwipeRefreshLayout or similar, I recommend to implement this method in the Activity/Fragment from the OnActionStateListener interface, because it is not compatible with dragging and so you can properly disable/enable the layout.
• onItemReleased() is instead called when the ItemTouchHelper has completed the move or swipe, and the active item state should be cleared. FlexibleViewHolder class already provides an implementation to disable the active state.

Note: OnActionStateListener is already extended by the listeners OnItemMoveListener and OnItemSwipeListener.