content: /*
   *  The MIT License (MIT)
   *
   *  Copyright (c) 2015 cpoopc
   *
   *  Permission is hereby granted, free of charge, to any person obtaining a copy
   *  of this software and associated documentation files (the "Software"), to deal
   *  in the Software without restriction, including without limitation the rights
   *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   *  copies of the Software, and to permit persons to whom the Software is
   *  furnished to do so, subject to the following conditions:
   *
   *  The above copyright notice and this permission notice shall be included in all
   *  copies or substantial portions of the Software.
   *
   *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   *  SOFTWARE.
   */
  package viewpager.lingdian.com.viewpagerdouble.view.scrollable;
  
  import android.annotation.SuppressLint;
  import android.os.Build;
  import android.support.v7.widget.LinearLayoutManager;
  import android.support.v7.widget.RecyclerView;
  import android.view.View;
  import android.webkit.WebView;
  import android.widget.AbsListView;
  import android.widget.AdapterView;
  import android.widget.ScrollView;
  
  /**
   * Created by cpoopc(303727604@qq.com) on 2015-02-10.
   */
  public class ScrollableHelper {
  
      private ScrollableContainer mCurrentScrollableCainer;
  
      /**
       * a viewgroup whitch contains ScrollView/ListView/RecycelerView..
       */
      public interface ScrollableContainer{
          /**
           * @return ScrollView/ListView/RecycelerView..'s instance
           */
          View getScrollableView();
      }
  
      public void setCurrentScrollableContainer(ScrollableContainer scrollableContainer) {
          this.mCurrentScrollableCainer = scrollableContainer;
      }
  
      private View getScrollableView() {
          if (mCurrentScrollableCainer == null) {
              return null;
          }
          return mCurrentScrollableCainer.getScrollableView();
      }
  
      /**
       *
       * 判断是否滑动到顶部方法,ScrollAbleLayout根据此方法来做一些逻辑判断
       * 目前只实现了AdapterView,ScrollView,RecyclerView
       * 需要支持其他view可以自行补充实现
       * @return
       */
      public boolean isTop() {
          View scrollableView = getScrollableView();
          if (scrollableView == null) {
  //            throw new NullPointerException("You should call ScrollableHelper.setCurrentScrollableContainer() to set ScrollableContainer.");
              return true;
          }
          if (scrollableView instanceof AdapterView) {
              return isAdapterViewTop((AdapterView) scrollableView);
          }
          if (scrollableView instanceof ScrollView) {
              return isScrollViewTop((ScrollView) scrollableView);
          }
          if (scrollableView instanceof RecyclerView) {
              return isRecyclerViewTop((RecyclerView) scrollableView);
          }
          if (scrollableView instanceof WebView) {
              return isWebViewTop((WebView) scrollableView);
          }
          throw new IllegalStateException("scrollableView must be a instance of AdapterView|ScrollView|RecyclerView");
      }
  
      private static boolean isRecyclerViewTop(RecyclerView recyclerView) {
          if (recyclerView != null) {
              RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
              if (layoutManager instanceof LinearLayoutManager) {
                  int firstVisibleItemPosition = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
                  View childAt = recyclerView.getChildAt(0);
                  if (childAt == null || (firstVisibleItemPosition == 0 && childAt.getTop() == 0)) {
                      return true;
                  }
              }
          }
          return false;
      }
  
      private static boolean isAdapterViewTop(AdapterView adapterView){
          if(adapterView != null){
              int firstVisiblePosition = adapterView.getFirstVisiblePosition();
              View childAt = adapterView.getChildAt(0);
              if(childAt == null || (firstVisiblePosition == 0 && childAt.getTop() == 0)){
                  return true;
              }
          }
          return false;
      }
  
      private static boolean isScrollViewTop(ScrollView scrollView){
          if(scrollView != null) {
              int scrollViewY = scrollView.getScrollY();
              return scrollViewY <= 0;
          }
          return false;
      }
  
      private static boolean isWebViewTop(WebView scrollView){
          if(scrollView != null) {
              int scrollViewY = scrollView.getScrollY();
              return scrollViewY <= 0;
          }
          return false;
      }
  
      @SuppressLint("NewApi")
      public void smoothScrollBy(int velocityY, int distance, int duration) {
          View scrollableView = getScrollableView();
          if (scrollableView instanceof AbsListView) {
              AbsListView absListView = (AbsListView) scrollableView;
              if (Build.VERSION.SDK_INT >= 21) {
                  absListView.fling(velocityY);
              } else {
                  absListView.smoothScrollBy(distance, duration);
              }
          } else if (scrollableView instanceof ScrollView) {
              ((ScrollView) scrollableView).fling(velocityY);
          } else if (scrollableView instanceof RecyclerView) {
              ((RecyclerView) scrollableView).fling(0, velocityY);
          } else if (scrollableView instanceof WebView) {
              ((WebView) scrollableView).flingScroll(0, velocityY);
          }
      }
  
  }
  