BGAScrollingUtil.java

package com.cheng.animationstudy.customview.bagrefresh;

import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebView;
import android.widget.AbsListView;
import android.widget.ScrollView;

import com.cheng.animationstudy.customview.bagrefresh.BGAStickyNavLayout;

/**
 * 作者:王浩 邮件:bingoogolapple@gmail.com
 * 创建时间:15/10/28 上午2:26
 * 描述:
 */
public class BGAScrollingUtil {

    private BGAScrollingUtil() {
    }

    public static boolean isScrollViewOrWebViewToTop(View view) {
        return view != null && view.getScrollY() == 0;
    }

    public static boolean isAbsListViewToTop(AbsListView absListView) {
        if (absListView != null) {
            int firstChildTop = 0;
            if (absListView.getChildCount() > 0) {
                // 如果AdapterView的子控件数量不为0，获取第一个子控件的top
                firstChildTop = absListView.getChildAt(0).getTop() - absListView.getPaddingTop();
            }
            if (absListView.getFirstVisiblePosition() == 0 && firstChildTop == 0) {
                return true;
            }
        }
        return false;
    }

    public static boolean isRecyclerViewToTop(RecyclerView recyclerView) {
        if (recyclerView != null) {
            int firstChildTop = 0;
            if (recyclerView.getChildCount() > 0) {
                // 如果RecyclerView的子控件数量不为0，获取第一个子控件的top

                // 解决item的topMargin不为0时不能触发下拉刷新
                ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) recyclerView.getChildAt(0).getLayoutParams();
                firstChildTop = recyclerView.getChildAt(0).getTop() - layoutParams.topMargin - recyclerView.getPaddingTop();
            }

            RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
            if (manager == null) {
                return true;
            }
            if (manager.getItemCount() == 0) {
                return true;
            }

            if (manager instanceof LinearLayoutManager) {
                LinearLayoutManager layoutManager = (LinearLayoutManager) manager;
                if (layoutManager.findFirstCompletelyVisibleItemPosition() == 0 && firstChildTop == 0) {
                    return true;
                }
            } else if (manager instanceof StaggeredGridLayoutManager) {
                StaggeredGridLayoutManager layoutManager = (StaggeredGridLayoutManager) manager;

                int[] out = layoutManager.findFirstCompletelyVisibleItemPositions(null);
                if (out[0] == 0) {
                    return true;
                }
            }
        }
        return false;
    }

    public static boolean isStickyNavLayoutToTop(BGAStickyNavLayout stickyNavLayout) {
        return isScrollViewOrWebViewToTop(stickyNavLayout) && stickyNavLayout.isContentViewToTop();
    }

    public static boolean isWebViewToBottom(WebView webView) {
        return webView != null && webView.getContentHeight() * webView.getScale() == (webView.getScrollY() + webView.getMeasuredHeight());
    }

    public static boolean isScrollViewToBottom(ScrollView scrollView) {
        if (scrollView != null) {
            int scrollContentHeight = scrollView.getScrollY() + scrollView.getMeasuredHeight() - scrollView.getPaddingTop() - scrollView.getPaddingBottom();
            int realContentHeight = scrollView.getChildAt(0).getMeasuredHeight();
            if (scrollContentHeight == realContentHeight) {
                return true;
            }
        }
        return false;
    }
}