检查ScrollView是否已到达布局的顶部

Question

是否可以检查ScrollView是否在顶部滚动？

我想检查一下,这样我就可以启用SwipeRefreshLayout,否则将其禁用.

使用ListView可以像这样完成,但ScrollViews没有setOnScrollListener

listView.setOnScrollListener(new OnScrollListener() {

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        boolean enable = false;
        if(listView != null && listView.getChildCount() > 0){
            // check if the first item of the list is visible
        boolean firstItemVisible = listView.getFirstVisiblePosition() == 0;
        // check if the top of the first item is visible
        boolean topOfFirstItemVisible = listView.getChildAt(0).getTop() == 0;
        // enabling or disabling the refresh layout
        enable = firstItemVisible && topOfFirstItemVisible;
    }
    swipeRefreshLayout.setEnabled(enable);
}
});

Answer 1

此链接可能对您有所帮助.它显示了如何设置滚动侦听器ScrollView.然后,请参阅@antonio的答案.

对于你的情况,它将是:

    mScrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
        @Override
        public void onScrollChanged() {
            int scrollY = mScrollView.getScrollY(); //for verticalScrollView
            if (scrollY == 0) 
                swipeRefresh.setEnabled(true);
            else 
                swipeRefresh.setEnabled(false);
        }
    });