import * as echarts from '../../ec-canvas/echarts';
var chart = null;
var chartObj, chartPromise;

Page({
  data: {
    ec: {
      onInit: function (canvas, width, height, dpr) {
        chart = echarts.init(canvas, null, {
          width: width,
          height: height,
          devicePixelRatio: dpr // new
        });
        canvas.setChart(chart);
        chartObj(chart)
        return chart;
      },
      // lazyLoad: true
    },
  },

  onLoad() {
    chartPromise = new Promise((r,j) => {
      chartObj = r
    })
　　
　　const data = ['假装请求接口,获取data'];

  　this.drawChart(data);//在这里异步获取数据,渲染echarts  },

})

 <view class="ec-box">
      <ec-canvas id="mychart" canvas-id="mychart-bar" ec="{{ ec }}" style="opacity:{{show ? 0 : 1}}"></ec-canvas>
      <image wx:if="{{show}}" src="{{chartImg}}"></image>
    </view>

// 转图片
    handleCanvarToImg(that) {
      let canvas = this.selectComponent('#mychart')
      if(!canvas){
        return
      }
      canvas.canvasToTempFilePath({
        x: 0,
        y: 0,
        width: 369,
        height: 253,
        canvasId: 'mychart',
        success: function(res) {
          that.setData({ chartImg: res.tempFilePath,showCanvas:true});
        }
      },that);
    },