android - 如何在scrollChange事件上获取android Horizo​​ntal scrollview的First Visible子项

我需要在scrollchange事件上找到android水平scrollview的第一个可见子项。我已关注此链接How to get First Visible child item of android scrollview on scrollChange event
但找不到rowview是什么。

    horizontalScrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
    @Override
    public void onScrollChanged() {
        int scrollPos = horizontalScrollView1.getScrollX();
        Log.e("scroll x:", scrollPos + "");
    }
});

布局文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <HorizontalScrollView
        android:id="@+id/horizontalScrollView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_gravity="center_horizontal"
        android:layout_marginBottom="15dp"
        android:fillViewport="true"
        android:scrollbars="none">
        <RelativeLayout
        android:id="@+id/layLandmarks"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
            <View
                android:id="@+id/viewWhite"
                android:layout_width="match_parent"
                android:layout_height="10dp"
                android:layout_centerInParent="true"
                android:background="@color/white" />

        </RelativeLayout>
    </HorizontalScrollView>
</RelativeLayout>

类文件：

    ImageView iv;
RelativeLayout layLandmarks = (RelativeLayout) findViewById(R.id.layLandmarks);
FrameLayout.LayoutParams lp1 = new FrameLayout.LayoutParams(2000, FrameLayout.LayoutParams.WRAP_CONTENT);
layLandmarks.setLayoutParams(lp1);
JSONObject landmarks = jsonObject1.getString("landmarks");
JSONArray jsonArray1 = new JSONArray(landmarks);
for (int j = 0; j < jsonArray1.length(); j++) {
JSONObject jsonObject2 = jsonArray1.getJSONObject(0);

landmarkId = jsonObject2.getString("id");
landmarkName = jsonObject2.getString("title");
landmarkDesc = jsonObject2.getString("description");
latitude = jsonObject2.getDouble("latitude");
longitude = jsonObject2.getDouble("longitude");
video_time = jsonObject2.getString("video_time_in_sec");
//   Log.e("video_time_in_sec", video_time);
landmarkIcon = jsonObject2.getString("image");
iv = new ImageView(VideoPreviewWithRecycler.this);
iv.setId(i);
Picasso
        .with(VideoPreviewWithRecycler.this)
        .load(landmarkIcon)
        .resize(40, 45)
        .into(iv);
params = new RelativeLayout.LayoutParams(40, 45);

params.topMargin = 0;

params.leftMargin = Integer.parseInt(video_time);
params.addRule(RelativeLayout.RIGHT_OF, 0);

layLandmarks.addView(iv, params);
}

更新：

 horizontalScrollView1.setOnScrollChangeListener(new View.OnScrollChangeListener() {
                        @Override
                        public void onScrollChange(View v, final int scrollX, int scrollY, final int oldScrollX, int oldScrollY) {

                            horizontalScrollView1.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
                                @Override
                                public void onGlobalLayout() {

                                   int firstVisibleItemIndex= getFirstVisibleItem1(horizontalScrollView1);
                                   Log.e("firstVisibleItemIndex >>",firstVisibleItemIndex+"");
                                }

                            });
                        }
                    });


 private int getFirstVisibleItem1(HorizontalScrollView scrollView) {
        ViewGroup viewGroup = (ViewGroup) scrollView.getChildAt(0); // cast to ViewGroup here because I think we only need to getFirstVisibleItem if ScrollView have multiple items
        for (int i = 0; i < viewGroup.getChildCount(); i++) {
            View view = viewGroup.getChildAt(i);
            if (view.getX() + view.getWidth() >= scrollView.getScrollX()) {
                return i; // if you want to receive the position, return  i here
            }
        }
        return 0;
    }

最佳答案

我想可能会有帮助

private View getFirstVisibleItem(HorizontalScrollView scrollView) {
    ViewGroup viewGroup = (ViewGroup) scrollView.getChildAt(0); // cast to ViewGroup here because I think we only need to getFirstVisibleItem if ScrollView have multiple items
    for (int i = 0; i < viewGroup.getChildCount(); i++) {
        View view = viewGroup.getChildAt(i);
        if (view.getX() + view.getWidth() >= scrollView.getScrollX()) {
            return view; // if you want to receive the position, return turn i here
        }
    }
    return null;
}

想法是检查每个view x position和scroll x value