饼图label中的position问题echarts 饼配置项内容和展示

当前效果：鼠标移到饼图item上时，value和百分比显示在饼图上。 期望效果：鼠标移到饼图item上时，value和百分比显示在饼图的中心（center），鼠标移出饼图时，显示截图所示样子（饼图里面显示SABCD） 在normal.position = ‘inner’， emphasis.position = 'center'。我是这样设置的，当时效果没达到预期

      option = {
    tooltip: {
            trigger: 'item',
            formatter: "{a} <br/>{b}: {c} ({d}%)",
            position: function(point, params, dom, rect, size) {
				var boxWidth = size.contentSize[0]
				var boxHeight = size.contentSize[1]
				var viewWidth = size.viewSize[0]
				var viewHeight = size.viewSize[1]
				var posX = 0
				var posY = 0
				posX = (viewWidth - boxWidth)/2
				posY = (viewHeight - boxHeight)/2
				return [posX, posY]
			},
          },
          // legend: {
          //   orient: 'vertical',
          //   x: 'left',
          //   data: ['S', 'A', 'B', 'C', 'D']
          // },
          series: [
            {
              name: '等级',
              type: 'pie',
              radius: ['40%', '70%'],
              avoidLabelOverlap: false,
              label: {
                normal: {
                  show: true,
                  position: 'inner',
                  textStyle: {
                    fontSize: '14',
                    fontWeight: '500'
                  }
                },
                emphasis: {
                  show: true,
                  position: 'center',
                  textStyle: {
                    fontSize: '20',
                    fontWeight: '500'
                  },
                  formatter: function (params) {
                    return params['percent'] + '%\n' + params.value
                  }
                }
              },
              labelLine: {
                normal: {
                  show: false
                }
              },
              data: [
                {value: 100, name: 'S'},
                {value: 200, name: 'A'},
                {value: 220, name: 'B'},
                {value: 280, name: 'C'},
                {value: 400, name: 'D'}
              ]
            }
          ]
};