ColeMurray

static class VisibilityChecker {
        private final Rect mClipRect = new Rect();


        boolean isVisible(@Nullable final View view, final int minPercentageViewed) {
            if (view == null || view.getVisibility() != View.VISIBLE || view.getParent() == null) {
                return false;
            }

            if (!view.getGlobalVisibleRect(mClipRect)) {

ColeMurray

class VisibilityRunnable implements Runnable {
        private final List<View> mVisibleViews;
        private final List<View> mInvisibleViews;
        private VisibilityChecker mVisibilityChecker;

        VisibilityRunnable() {
            mVisibleViews = new ArrayList<>();
            mInvisibleViews = new ArrayList<>();
        }

ColeMurray

public class VisibilityTracker {
    private static final long VISIBILITY_CHECK_DELAY_MILLIS = 100;
    private WeakHashMap<View, TrackingInfo> mTrackedViews = new WeakHashMap<>();
    private ViewTreeObserver.OnPreDrawListener mOnPreDrawListener;
    private VisibilityTrackerListener mVisibilityTrackerListener;
    private boolean mIsVisibilityCheckedScheduled;
    private Handler mVisibilityHandler;
    private VisibilityChecker mVisibilityChecker;
    private Runnable mVisibilityRunnable;

ColeMurray

    public ImpressionAdapter(Activity activity, List<String> dataSet) {
        mDataSet = dataSet;
        mVisibilityTracker = new VisibilityTracker(activity);

        mVisibilityTracker.setVisibilityTrackerListener(new VisibilityTracker.VisibilityTrackerListener() {
            @Override
            public void onVisibilityChanged(List<View> visibleViews, List<View> invisibleViews) {
                handleVisibleViews(visibleViews);
            }
        });

ColeMurray

public class VisibilityTracker {
    private WeakHashMap<View, TrackingInfo> mTrackedViews = new WeakHashMap<>();
    private ViewTreeObserver.OnPreDrawListener mOnPreDrawListener;

    public interface VisibilityTrackerListener {
        void onVisibilityChanged(List<View> visibleViews, List<View> invisibleViews);
    }

    static class TrackingInfo {
        View mRootView;

ColeMurray

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:tools="http://schemas.android.com/tools"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:background="@color/background_floating_material_dark"
                android:paddingBottom="@dimen/activity_vertical_margin"
                android:paddingLeft="@dimen/activity_horizontal_margin"
                android:paddingRight="@dimen/activity_horizontal_margin"
                android:paddingTop="@dimen/activity_vertical_margin"
                tools:context=".MainActivityFragment">

ColeMurray

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:tools="http://schemas.android.com/tools"
              android:layout_width="match_parent"
              android:layout_height="240dp"
              android:gravity="center"
              android:orientation="vertical">

    <TextView
        android:id="@+id/title_textview"

ColeMurray

public class ImpressionAdapter extends RecyclerView.Adapter<ProductViewHolder> {
    private List<String> mDataSet;

    public ImpressionAdapter(Activity activity, List<String> dataSet) {
        mDataSet = dataSet;
    }

    @Override
    public ProductViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.product_item_layout, viewGroup, false);

ColeMurray

public class MainActivityFragment extends Fragment {
    private RecyclerView mRecyclerView;
    private ArrayList<String> mDataSet = new ArrayList<>();

    public MainActivityFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

ColeMurray

class VisibilityRunnable implements Runnable {
        private final List<View> mVisibleViews;
        private final List<View> mInvisibleViews;
        private VisibilityChecker mVisibilityChecker;

        VisibilityRunnable() {
            mVisibleViews = new ArrayList<>();
            mInvisibleViews = new ArrayList<>();
        }