Android开发在RecyclerView上面实现"拖放"和"滑动删除"-2

<FrameLayout xmlns:android="http://scheR_710_11845@as.android.com/apk/res/android"
 android:id="@+id/item"
 android:layout_width="match_parent"
 android:layout_height="?listPreferredItemHeight"
 android:clickable="true"
 android:focusable="true"
 android:foreground="?SELEctableItemBACkground">
 <TextView
 android:id="@+id/text"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_gravity="center_vertical"
 android:layout_marginLeft="16dp"
 android:textAppearance="?android:attr/textAppearanceMedium" />
 <ImageView
 android:id="@+id/handle"
 android:layout_width="?listPreferredItemHeight"
 android:layout_height="match_parent"
 android:layout_gravity="center_vertical|right"
 android:scaleType="center"
 android:src="@drawable/ic_reorder_grey_500_24dp" />
</FrameLayout>

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);
}

public final ImageView handleView;
public ItemViewHolder(View itemView) {
 super(itemView);
 // ...
 handleView = (ImageView) itemView.findViewById(R.id.handlE);
}

private final OnStartDragListener mDragStartListener;
public Recyclerlistadapter(OnStartDragListener dragStartListener) {
 mDragStartListener = dragStartListener;
 // ...
}
@Override
public void onBindViewHolder(final ItemViewHolder holder,int position) {
 // ...
 holder.handleView.setOnTouchListener(new OnTouchListener() {
 @Override
 public Boolean onTouch(View v,MotionEvent event) {
 if (MotionEventCompat.getActionMasked(event) == 
  MotionEvent.ACTION_DOWN) {
 mDragStartlistener.onStartDrag(holder);
 }
 return false;
 }
 });
}

public class RecyclerListFragment extends Fragment implements 
 OnStartDragListener {
 // ...
 @Override
 public void onViewCreated(View view,Bundle iciclE) {
 super.onViewCreated(view,iciclE);
 Recyclerlistadapter a = new Recyclerlistadapter(this);
 // ...
 }
 @Override
 public void onStartDrag(RecyclerView.ViewHolder viewHolder) {
 mitemtouchhelper.startDrag(viewHolder);
 }
}

/**
 * Notifies a View Holder of relevant callBACks from 
 * {@link itemtouchhelper.CallBACk}.
 */
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();
}

@Override
public void onSELEctedChanged(RecyclerView.ViewHolder viewHolder,int actionStatE) {
 // We only want the active item
 if (actionState != itemtouchhelper.ACTION_STATE_IDLE) {
 if (viewHolder instanceof itemtouchhelperViewHolder) {
 itemtouchhelperViewHolder itemViewHolder = 
  (itemtouchhelperViewHolder) viewHolder;
 itemViewHolder.onItemSELEcted();
 }
 }
 super.onSELEctedChanged(viewHolder,actionStatE);
}
@Override
public void clearView(RecyclerView recyclerView,RecyclerView.ViewHolder viewHolder) {
 super.clearView(recyclerView,viewHolder);

 if (viewHolder instanceof itemtouchhelperViewHolder) {
 itemtouchhelperViewHolder itemViewHolder = 
 (itemtouchhelperViewHolder) viewHolder;
 itemViewHolder.onItemClear();
 }
}

public class ItemViewHolder extends RecyclerView.ViewHolder 
 implements itemtouchhelperViewHolder {
 // ...
 @Override
 public void onItemSELEcted() {
 itemView.setBACkgroundColor(Color.LTGRAY);
 }
 @Override
 public void onItemClear() {
 itemView.setBACkgroundColor(0);
 }
}

@Override
public int getMovementFlags(RecyclerView recyclerView,RecyclerView.ViewHolder viewHolder) {
 int dragFlags = itemtouchhelper.UP | itemtouchhelper.DOWN;
 int swipeFlags = itemtouchhelper.START | itemtouchhelper.END;
 return makeMovementFlags(dragFlags,swipeFlags);
}

int dragFlags = itemtouchhelper.UP | itemtouchhelper.DOWN | 
 itemtouchhelper.LEFT | itemtouchhelper.RIGHT;

@Override
public int getMovementFlags(RecyclerView recyclerView,RecyclerView.ViewHolder viewHolder) {
 int dragFlags = itemtouchhelper.UP | itemtouchhelper.DOWN | 
  itemtouchhelper.LEFT | itemtouchhelper.RIGHT;
 int swipeFlags = 0;
 return makeMovementFlags(dragFlags,swipeFlags);
}

@Override
public void onChildDraw(Canvas c,RecyclerView recyclerView,ViewHolder viewHolder,float dX,float dY,int actionState,Boolean isCurrentlyActivE) {
 if (actionState == itemtouchhelper.ACTION_STATE_SWIPE) {
 float width = (float) viewHolder.itemView.getWidth();
 float alpha = 1.0f - Math.abs(dX) / width;
 viewHolder.itemView.setAlpha(alpha);
 viewHolder.itemView.setTranslationX(dX); 
 } else {
 super.onChildDraw(c,recyclerView,viewHolder,dX,dY,actionState,isCurrentlyActivE);
 }
}