安卓MPChart如何显示自定义标记？

LineChart lineChart = findViewById(R.id.lineChart);

public class CustomMarkerView extends MarkerView {

    private TextView tvContent;

    public CustomMarkerView(Context context, int layoutResource) {
        super(context, layoutResource);
        tvContent = findViewById(R.id.tvContent);
    }

    @Override
    public void refreshContent(Entry e, Highlight highlight) {
        tvContent.setText("Value: " + e.getY());
        super.refreshContent(e, highlight);
    }

    @Override
    public MPPointF getOffset() {
        return new MPPointF(-(getWidth() / 2), -getHeight());
    }
}

CustomMarkerView markerView = new CustomMarkerView(this, R.layout.custom_marker_view);
lineChart.setMarker(markerView);