OnScrollListener接口是定義在AbsListView中的,而AbsListView的直接子類有GridView和ListView,非直接子類有ExpandableListView。OnScrollListener的完整路徑是frameworks\base\core\java\Android\widget\AbsListView.java,代碼如下:
[java]
- /**
- * Interface definition for a callback to be invoked when the list or grid
- * has been scrolled.
- */
- public interface OnScrollListener {
-
- /**
- * The view is not scrolling. Note navigating the list using the trackball counts as
- * being in the idle state since these transitions are not animated.
- */
- public static int SCROLL_STATE_IDLE = 0;
-
- /**
- * The user is scrolling using touch, and their finger is still on the screen
- */
- public static int SCROLL_STATE_TOUCH_SCROLL = 1;
-
- /**
- * The user had previously been scrolling using touch and had performed a fling. The
- * animation is now coasting to a stop
- */
- public static int SCROLL_STATE_FLING = 2;
-
- /**
- * Callback method to be invoked while the list view or grid view is being scrolled. If the
- * view is being scrolled, this method will be called before the next frame of the scroll is
- * rendered. In particular, it will be called before any calls to
- * {@link Adapter#getView(int, View, ViewGroup)}.
- *
- * @param view The view whose scroll state is being reported
- *
- * @param scrollState The current scroll state. One of {@link #SCROLL_STATE_IDLE},
- * {@link #SCROLL_STATE_TOUCH_SCROLL} or {@link #SCROLL_STATE_IDLE}.
- */
- public void onScrollStateChanged(AbsListView view, int scrollState);
-
- /**
- * Callback method to be invoked when the list or grid has been scrolled. This will be
- * called after the scroll has completed
- * @param view The view whose scroll state is being reported
- * @param firstVisibleItem the index of the first visible cell (ignore if
- * visibleItemCount == 0)
- * @param visibleItemCount the number of visible cells
- * @param totalItemCount the number of items in the list adaptor
- */
- public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
- int totalItemCount);
- }