Android 实现 ScrollView setOnScrollChangeListener

Question

在我用于显示和隐藏一些小部件的应用程序中，我在本网站的以下代码中找到了这个，但我无法在我的片段上实现它，例如：

public abstract class HidingScrollListener extends RecyclerView.OnScrollListener {
    private static final int HIDE_THRESHOLD = 20;
    private int mScrolledDistance = 0;
    private boolean mControlsVisible = true;
    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);

        int firstVisibleItem = ((LinearLayoutManager) recyclerView.getLayoutManager()).findFirstVisibleItemPosition();

        if (firstVisibleItem == 0) {
            if(!mControlsVisible) {
                onShow();
                mControlsVisible = true;
            }
        } else {
            if (mScrolledDistance > HIDE_THRESHOLD && mControlsVisible) {
                onHide();
                mControlsVisible = false;
                mScrolledDistance = 0;
            } else if (mScrolledDistance < -HIDE_THRESHOLD && !mControlsVisible) {
                onShow();
                mControlsVisible = true;
                mScrolledDistance = 0;
            }
        }
        if((mControlsVisible && dy>0) || (!mControlsVisible && dy<0)) {
            mScrolledDistance += dy;
        }
    }

    public abstract void onHide();
    public abstract void onShow();
}

我的片段：

public class FragmentMarketDetail extends Fragment implements ObservableHorizontalScrollView.OnScrollListener {

    private ScrollView scrollViewTest;
    private Context    context;

    public static FragmentMarketDetail newInstance() {
        FragmentMarketDetail fragmentFirst = new FragmentMarketDetail();
        return fragmentFirst;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_online_categories, container, false);
        scrollViewTest = (ScrollView) view.findViewById(R.id.scrollViewTest);
        scrollViewTest.setOnScrollChangeListener(context);
        return view;
    }

    @Override
    public void onScrollChanged(ObservableHorizontalScrollView scrollView, int x, int y, int oldX, int oldY) {
        Log.e("-----> onScrollChanged", x + "");
    }

    @Override
    public void onEndScroll(ObservableHorizontalScrollView scrollView) {
        Log.e("----->onEndScroll ", "");

    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        context = activity;
    }
}

我收到此行的错误：scrollViewTest.setOnScrollChangeListener(context);

Answer 1

您不能将 onScrollChangedListener 设置为 API23 正下方的 ScrollView。 但是你可以使用这个

scrollView.getViewTreeObserver().addOnScrollChangedListener(new OnScrollChangedListener() {

    @Override
    public void onScrollChanged() {

        int scrollX = rootScrollView.getScrollX(); //for horizontalScrollView
        int scrollY = rootScrollView.getScrollY(); //for verticalScrollView
        //DO SOMETHING WITH THE SCROLL COORDINATES

    }
});

见onScrollListener for a ScrollView

编辑

scrollViewTest.setOnScrollChangeListener(context);

在上述行中，您试图将Context 设置为不可能的侦听器，因为您应该调用Fragment 实现ObservableHorizontalScrollView.OnScrollListener

scrollViewTest.setOnScrollChangeListener(this);