code: function() {
          var wxPie = new WxChart.WxDoughnut('basePie', {
              width: canvasWidth,
              height: canvasHeight,
              title: '销售量',
              cutoutPercentage: 0,
              point: {
                  format : percentageFormatLabel
              }
          });
  
          var datas = dataGenerator(labels);
          wxPie.update(datas);
          return wxPie;
      }
docs: 饼图