listview计算滑动高度判断上滑下滑隐藏控件

最新推荐文章于 2018-04-10 21:57:51 发布

转载最新推荐文章于 2018-04-10 21:57:51 发布 · 467 阅读

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本文介绍了一个具体的Android ListView滑动监听实现方案，通过自定义OnScrollListener来处理ListView滚动状态变化及滚动过程中的各种需求，例如加载更多数据、顶部图片的显示隐藏等。文章深入解析了如何使用SparseArray记录每个可见项的高度和位置，以便于精确计算ListView的滚动距离。

lv_followlistview.setOnScrollListener(new AbsListView.OnScrollListener() {

    private SparseArray recordSp = new SparseArray(0);
    private int mCurrentfirstVisibleItem = 0;

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        if (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_IDLE && lastItemIndex == followListAdapter.getCount() - 1) {
            onLoad();
        }
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        lastItemIndex = firstVisibleItem + visibleItemCount - 1;
        mCurrentfirstVisibleItem = firstVisibleItem;
        View firstView = view.getChildAt(0);
        if (null != firstView) {
            ItemRecod itemRecord = (ItemRecod) recordSp.get(firstVisibleItem);
            if (null == itemRecord) {
                itemRecord = new ItemRecod();
            }
            itemRecord.height = firstView.getHeight();
            itemRecord.top = firstView.getTop();
            recordSp.append(firstVisibleItem, itemRecord);
            int temp = h;
            h = getScrollY();
            //滚动距离
            if (temp - h > 3) {
                Log.i(TAG, "temp = \t\t\t1\t" + (h - temp));
                image.setVisibility(View.VISIBLE);
            } else if (temp - h < -3) {
                Log.i(TAG, "temp = \t\t\t2\t" + (h - temp));
                image.setVisibility(View.GONE);
            }
            Log.i(TAG, "hhhhhhhhhhhhhhhh = " + h);
            //在此进行你需要的操作//TODO
        }
    }

    private int getScrollY() {
        int height = 0;
        for (int i = 0; i < mCurrentfirstVisibleItem; i++) {
            ItemRecod itemRecod = (ItemRecod) recordSp.get(i);
            height += itemRecod.height;
        }
        ItemRecod itemRecod = (ItemRecod) recordSp.get(mCurrentfirstVisibleItem);
        if (null == itemRecod) {
            itemRecod = new ItemRecod();
        }
        return height - itemRecod.top;
    }

    class ItemRecod {
        int height = 0;
        int top = 0;
    }
});