Taro引入echarts【兼容多端小程序（飞书/微信/支付宝小程序）】

近期接到公司新需求，开发飞书小程序，并且原型中含有大量的图表，本想使用飞书内置图表组件 ------

chart-space，但官方表示已经停止维护了，无奈之下，只能另寻他路，于是乎，图表之王（文档最完整，api最透彻，社区最活跃）echarts映入我脑海中，决定就是你了！

下载echarts代码

进入echarts下载地址，点击在线定制

勾选你需要的图表和组件，点击下载

echarts引入项目

在开发项目中，components中创建Echarts文件，放入下载后的js包，并在该目录下创建wx-canvas.js，编写canvas构造函数代码，如下

export default class WxCanvas {
  constructor(ctx, canvasId, isNew, canvasNode) {
    this.ctx = ctx;
    this.canvasId = canvasId;
    this.chart = null;
    this.isNew = isNew
    if (isNew) {
      this.canvasNode = canvasNode;
    }
    else {
      this._initStyle(ctx);
    }

    // this._initCanvas(zrender, ctx);

    this._initEvent();
  }

  getContext(contextType) {
    if (contextType === '2d') {
      return this.ctx;
    }
  }

  // canvasToTempFilePath(opt) {
  //   if (!opt.canvasId) {
  //     opt.canvasId = this.canvasId;
  //   }
  //   return wx.canvasToTempFilePath(opt, this);
  // }

  setChart(chart) {
    this.chart = chart;
  }

  addEventListener() {
    // noop
  }

  attachEvent() {
    // noop
  }

  detachEvent() {
    // noop
  }

  _initCanvas(zrender, ctx) {
    zrender.util.getContext = function () {
      return ctx;
    };

    zrender.util.$override('measureText', function (text, font) {
      ctx.font = font || '12px sans-serif';
      return ctx.measureText(text);
    });
  }

  _initStyle(ctx) {
    ctx.createRadialGradient = () => {
      return ctx.createCircularGradient(arguments);
    };
  }

  _initEvent() {
    this.event = {};
    const eventNames = [{
      wxName: 'touchStart',
      ecName: 'mousedown'
    }, {
      wxName: 'touchMove',
      ecName: 'mousemove'
    }, {
      wxName: 'touchEnd',
      ecName: 'mouseup'
    }, {
      wxName: 'touchEnd',
      ecName: 'click'
    }];
    eventNames.forEach(name => {
      this.event[name.wxName] = e => {
        const touch = e.touches[0];
        this.chart.getZr().handler.dispatch(name.ecName, {
          zrX: name.wxName === 'tap' ? touch.clientX : touch.x,
          zrY: name.wxName === 'tap' ? touch.clientY : touch.y,
          preventDefault: () => {},
          stopImmediatePropagation: () => {},
          stopPropagation: () => {}
        });
      };
    });
  }

  set width(w) {
    if (this.canvasNode) this.canvasNode.width = w
  }
  set height(h) {
    if (this.canvasNode) this.canvasNode.height = h
  }

  get width() {
    if (this.canvasNode)
      return this.canvasNode.width
    return 0
  }
  get height() {
    if (this.canvasNode)
      return this.canvasNode.height
    return 0
  }
}

目录结构如下图

在Echarts文件中，创建ec-canvas.vue文件，创建canvas对象

<template>
  <!--  // 多个echarts时将canvasId作为唯一标识，动态获取canvasId用于多个echarts可同时显示    -->
  <canvas
    type="2d"
    class="ec-canvas"
    :id="canvasId"
    :canvas-id="canvasId"
    @touchStart="touchStart"
    @touchMove="touchMove"
    @touchEnd="touchEnd"
  ></canvas>
</template>

<script lang="js">
import Taro from "@tarojs/taro";
import WxCanvas from "@/components/Echarts/wx-canvas";
import * as echarts from "@/components/Echarts/echarts.min";

export default {
  name: "EcCanvas",
  props: {
    canvasId: {
      type: String,
      default: "",
    },
    chartData: {
      type: Array,
      default: () => [],
    },
    option: {
      type: Object,
      default: () => {}
    }
  },
  data() {
    return {
    }
  },
  watch: {
    chartData: function() {
      console.log('chartData', this.chartData)
      this.handleCreate()
    },
  },
  mounted() {
    echarts.registerPreprocessor(option => {
      if (option && option.series) {
        if (option.series.length > 0) {
          option.series.forEach(series => {
            series.progressive = 0;
          });
        } else if (typeof option.series === "object") {
          option.series.progressive = 0;
        }
      }
    })
  },
  methods: {
    init(callback) {
      this.initByNewWay(callback);
    },
    // eslint-disable-next-line complexity
    handleCreate() {
      const option = this.option
      const v = this
      v.init((canvas, width, height, canvasDpr) => {
        const chart = echarts.init(canvas, null, {
            width: width,
            height: height,
            devicePixelRatio: canvasDpr,
        })
        canvas.setChart(chart);
        chart.setOption(option);
        chart.on('click', (params) => {
          console.log('params', params)
          this.$emit('clickEChartItem', params)
        });
        return chart;
      })
    },
    initByNewWay(callback) {
      const query = Taro.createSelectorQuery();

      query
        .select(`#${this.canvasId}`) // 根据canvasId动态获取不同的echarts图表
        .fields({
          // node: true, // 飞书里面没有node
          dataset: true,
          size: true,
        })
        // eslint-disable-next-line complexity
        .exec(res => {
          console.log('query res', res)
          // eslint-disable-next-line eqeqeq
          // if (!res || res.length == 0 || res[0] == null || res[0].node == null) {
          //   console.error('未获取到canvas的dom节点,请确认在页面渲染完成后或节点,taro中页面渲染完成的生命周期是useReady');
          //   return
          // }
          // const canvasNode = res[0].node;
          // this.canvasNode = canvasNode;
          console.log(11,this.option.height);
          const canvasDpr = Taro.getSystemInfoSync().pixelRatio;
          const canvasWidth = res[0].width;
          const canvasHeight = res[0].height;

          // const ctx = canvasNode.getContext("2d");
          const ctx = tt.createCanvasContext(this.canvasId)
          console.log('ctx', ctx)
          // const canvas = new WxCanvas(ctx, this.canvasId, true, canvasNode) // 不给canvasNode也可以
          const canvas = new WxCanvas(ctx, this.canvasId, true);
          echarts.setCanvasCreator(() => {
            return canvas;
          });

          this.chart = callback(canvas, canvasWidth, canvasHeight, canvasDpr)
        });
    },
    touchStart(e) {
      if (this.chart && e.touches.length > 0) {
        var touch = e.touches[0];
        var handler = this.chart.getZr().handler;
        handler.dispatch("mousedown", {
          zrX: touch.x,
          zrY: touch.y,
        });
        handler.dispatch("mousemove", {
          zrX: touch.x,
          zrY: touch.y,
        });
        handler.processGesture(this.wrapTouch(e), "start");
      }
    },
    touchMove(e) {
      if (this.chart && e.touches.length > 0) {
        var touch = e.touches[0];
        var handler = this.chart.getZr().handler;
        handler.dispatch("mousemove", {
          zrX: touch.x,
          zrY: touch.y,
        });
        handler.processGesture(this.wrapTouch(e), "change");
      }
    },
    touchEnd(e) {
      if (this.chart) {
        const touch = e.changedTouches ? e.changedTouches[0] : {};
        var handler = this.chart.getZr().handler;
        handler.dispatch("mouseup", {
          zrX: touch.x,
          zrY: touch.y,
        });
        handler.dispatch("click", {
          zrX: touch.x,
          zrY: touch.y,
        });
        handler.processGesture(this.wrapTouch(e), "end");
      }
    },
    wrapTouch(event) {
      for (let i = 0; i < event.touches.length; ++i) {
        const touch = event.touches[i];
        touch.offsetX = touch.x;
        touch.offsetY = touch.y;
      }
      return event;
    },
  },
};
</script>

<style>
.ec-canvas {
  width: 100%;
  height: 100%;
  min-height: 208px;
  flex: 1;
}
</style>

二次封装echarts组件

使用创建的echart组件，稍微进行二次封装，大佬可以用自己的方法封装更好的，我的思路是，页面只要给echarts传入不同option，就可以进行渲染，代码如下：

// eChart.vue
<template>
  <EcCanvas :ref="canvasId" :canvasId="canvasId" :option="option"></EcCanvas>
</template>

<script>
import EcCanvas from './ec-canvas.vue'
import { watch, ref, toRefs } from 'vue'

export default {
  components: {
    EcCanvas,
  },
  props: {
    canvasId: {
      type: String,
      default: () => '',
    },
    option: {
      type: Object,
      default: () => {},
    },
  },
  watch: {
    option: {
      handler(value) {
        this.$nextTick(() => { // 没有下一帧会出现无法渲染的问题 页面没有挂载完成
          this.$refs[this.canvasId] && this.$refs[this.canvasId].handleCreate()
        })
      },
      deep: true,
    },
  },
}
</script>

<style lang="scss">
</style>

使用echarts组件渲染页面

<template>
<view class="chart">
            <e-chart canvasId="canvasId" :option="option"></e-chart>
          </view>
 </template>
 
 <script>
 import eChart from '@/componets/Echart/eChart.vue'
 import { reactive}  from 'vue'

 export default {
	components: { eChart },
  setup() {
  	const state =  reactive({
  		option: {}
  	})
 onMounted(async () => {
     // 模拟在挂载后，进行数据请求，这边我直接对option赋值
     // 数据来源于echarts官方实例中，最基础的柱状图
     state.option = {
		xAxis: {
		    type: 'category',
		    data: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
		  },
		  yAxis: {
		    type: 'value'
		  },
		  series: [
		    {
		      data: [120, 200, 150, 80, 70, 110, 130],
		      type: 'bar'
		    }
	  	]
	}
    })
	return {
      ...toRefs(state),
    }
  }
}
 </script>
<style>
.chart {
        width: 100%;
        height: 300px;
    }
</style>

最后，需要进行各种各样的渲染与修改，可直接参看echarts官网

希望此文对大家有帮助，也请大佬不吝赐教～