title: Label can't display when ECharts label's length is too long
body: <p>I just use the treemap type of EChart to show the data. But I meet a problem. And the label option shows as the following:
      itemStyle:{
      normal:{
      label:{ show :true,
      formtter:"{b}"}</p>
  
  <p>If my data name's length is too long(maybe more than 60 characters), the label doesn't show on the Treemap. The Name will show on the tooltip. Why?
  How can I solve this problem? Thanks !</p>