Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Interfaces, and ItemTouchHelper.Callback implementation to assist in adding Swipe based gestures (Drag & Drop, Swipe to Dismiss) to a RecyclerView.
/*
* Copyright (C) 2015 Paul Burke
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package your.package.here;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.helper.ItemTouchHelper;
/**
* Interface to listen for a move or dismissal event from a {@link ItemTouchHelper.Callback}.
*
* @author Paul Burke (ipaulpro)
*/
public interface ItemTouchHelperAdapter {
/**
* Called when an item has been dragged far enough to trigger a move. This is called every time
* an item is shifted, and <strong>not</strong> at the end of a "drop" event.<br/>
* <br/>
* Implementations should call {@link RecyclerView.Adapter#notifyItemMoved(int, int)} after
* adjusting the underlying data to reflect this move.
*
* @param fromPosition The start position of the moved item.
* @param toPosition Then resolved position of the moved item.
* @return True if the item was moved to the new adapter position.
*
* @see RecyclerView#getAdapterPositionFor(RecyclerView.ViewHolder)
* @see RecyclerView.ViewHolder#getAdapterPosition()
*/
boolean onItemMove(int fromPosition, int toPosition);
/**
* Called when an item has been dismissed by a swipe.<br/>
* <br/>
* Implementations should call {@link RecyclerView.Adapter#notifyItemRemoved(int)} after
* adjusting the underlying data to reflect this removal.
*
* @param position The position of the item dismissed.
*
* @see RecyclerView#getAdapterPositionFor(RecyclerView.ViewHolder)
* @see RecyclerView.ViewHolder#getAdapterPosition()
*/
void onItemDismiss(int position);
}
/*
* Copyright (C) 2015 Paul Burke
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package your.package.here;
import android.support.v7.widget.helper.ItemTouchHelper;
/**
* Interface to notify an item ViewHolder of relevant callbacks from {@link
* ItemTouchHelper.Callback}.
*
* @author Paul Burke (ipaulpro)
*/
public interface ItemTouchHelperViewHolder {
/**
* Called when the {@link ItemTouchHelper} first registers an item as being moved or swiped.
* Implementations should update the item view to indicate it's active state.
*/
void onItemSelected();
/**
* Called when the {@link ItemTouchHelper} has completed the move or swipe, and the active item
* state should be cleared.
*/
void onItemClear();
}
/*
* Copyright (C) 2015 Paul Burke
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package your.package.here;
import android.support.v7.widget.RecyclerView;
/**
* Listener for manual initiation of a drag.
*/
public interface OnStartDragListener {
/**
* Called when a view is requesting a start of a drag.
*
* @param viewHolder The holder of the view to drag.
*/
void onStartDrag(RecyclerView.ViewHolder viewHolder);
}
/*
* Copyright (C) 2015 Paul Burke
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package your.package.here;
import android.graphics.Canvas;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.support.v7.widget.helper.ItemTouchHelper;
/**
* An implementation of {@link ItemTouchHelper.Callback} that enables basic drag & drop and
* swipe-to-dismiss. Drag events are automatically started by an item long-press.<br/>
* </br/>
* Expects the <code>RecyclerView.Adapter</code> to listen for {@link
* ItemTouchHelperAdapter} callbacks and the <code>RecyclerView.ViewHolder</code> to implement
* {@link ItemTouchHelperViewHolder}.
*
* @author Paul Burke (ipaulpro)
*/
public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback {
public static final float ALPHA_FULL = 1.0f;
private final ItemTouchHelperAdapter mAdapter;
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 if (recyclerView.getLayoutManager() instanceof StaggeredGridLayoutManager) {
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 dismissal
mAdapter.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's 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) {
// 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's time to restore the idle state
ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
itemViewHolder.onItemClear();
}
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.