Android ListView 当前滚动位置 Y 像素 [英] Android ListView current scroll location Y pixels

问题描述

我试图检测列表视图何时滚动超过以像素为单位的特定固定阈值(第一项的一半).不幸的是，listview 的 getScrollY() 似乎总是返回滚动位置的 0 instad.有没有办法按像素获取实际滚动位置?

I'm trying to detect when a list view is scrolled beyond certain fixed threshold in pixels (half way through the first item). Unfortunately listview's getScrollY() seems to always return 0 instad of the scroll position. Is there any way to get the actual scroll location by pixel?

这是我尝试使用的代码，但如上所述它只返回 0.

Here's the code I tried to use but as said it only returns 0.

getListView().setOnScrollListener(new AbsListView.OnScrollListener() {
    public void onScroll(AbsListView view, int firstVisibleItem,
                         int visibleItemCount, int totalItemCount) {
        Log.d("scroll", "scroll: " + getListView().getScrollY());
    }

    public void onScrollStateChanged(AbsListView view, int scrollState) {
        if (scrollState == 0)
        Log.d("scroll", "scrolling stopped");
    }
});

推荐答案

Android 中的 ListView 没有 Y 滚动的概念，因为内容的总高度是未知的.只有显示内容的高度是已知的.

There is no notion of Y scroll for a ListView in Android simply because the total height of the content is unknown. Only the height of the displayed content is known.

但是，可以使用以下技巧获取可见项目的当前位置/Y 滚动:

However it is possible to get the current position/Y scroll of a visible item using the following hack:

getListView().getChildAt(0).getTop();

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