content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.weex.ui.component.list;
  
  import android.support.annotation.NonNull;
  import android.support.annotation.Nullable;
  import android.support.v7.widget.OrientationHelper;
  import android.support.v7.widget.PagerSnapHelper;
  import android.support.v7.widget.RecyclerView;
  import android.view.View;
  
  public class WXPagerSnapHelper extends PagerSnapHelper {
      @Nullable
      private OrientationHelper mVerticalHelper;
      @Nullable
      private OrientationHelper mHorizontalHelper;
  
      @Nullable
      @Override
      public int[] calculateDistanceToFinalSnap(@NonNull RecyclerView.LayoutManager layoutManager, @NonNull View targetView) {
  
          int[] out = new int[2];
          if (layoutManager.canScrollHorizontally()) {
              out[0] = this.distanceToStart(layoutManager, targetView, this.getHorizontalHelper(layoutManager));
          } else {
              out[0] = 0;
          }
  
          if (layoutManager.canScrollVertically()) {
              out[1] = this.distanceToStart(layoutManager, targetView, this.getVerticalHelper(layoutManager));
          } else {
              out[1] = 0;
          }
  
          return out;
      }
  
      @NonNull
      private OrientationHelper getVerticalHelper(@NonNull RecyclerView.LayoutManager layoutManager) {
          if (this.mVerticalHelper == null) {
              this.mVerticalHelper = OrientationHelper.createVerticalHelper(layoutManager);
          }
  
          return this.mVerticalHelper;
      }
  
      @NonNull
      private OrientationHelper getHorizontalHelper(@NonNull RecyclerView.LayoutManager layoutManager) {
          if (this.mHorizontalHelper == null) {
              this.mHorizontalHelper = OrientationHelper.createHorizontalHelper(layoutManager);
          }
  
          return this.mHorizontalHelper;
      }
  
      private int distanceToStart(@NonNull RecyclerView.LayoutManager layoutManager, @NonNull View targetView, OrientationHelper helper) {
          return helper.getDecoratedStart(targetView) - helper.getStartAfterPadding();
      }
  }
  