Taro3+Vue3使用echarts

先上图，无图言吊

一.taro支持echarts

官方说明：https://taro-docs.jd.com/blog/2018-09-18-taro-1-0-0#支持引用小程序端第三方组件库

二.引入echarts-for-weixin插件

github地址: https://github.com/ecomfe/echarts-for-weixin

只引入ec-canvas文件夹下的wx-canvas.js

三.自定义下载echarts

地址: https://echarts.apache.org/zh/builder.html

可自行选择版本，笔者测试了5.3.3和5.4.1都支持

下载后得到echarts.min.js

请根据需要自行选择需要的图表打包下载，我只选了默认的饼图、柱图、线图;

四.封装组件ec-canvas.vue

<template>
  <canvas type="2d" class="ec-canvas" :canvas-id="canvasId" @touchStart="touchStart" @touchMove="touchMove"
    @touchEnd="touchEnd"></canvas>
</template>

引入刚才下载的echarts.min.js和wx-canvas

import Taro from "@tarojs/taro";
import WxCanvas from "./wx-canvas";
import * as echarts from "./echarts-5.4.1.min";

<script lang="js">
//自定义下载的echarts.min.js 文件  要使用需使用js,ts需要声明文件
import Taro from "@tarojs/taro";
import WxCanvas from "./wx-canvas";
import * as echarts from "./echarts-5.4.1.min";

export default {
  name: "EcCanvas",
  props: {
    canvasId: {
      type: String,
      default: ""
    },
    ec: {
      type: Object,
      default: null
    }
  },
  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;
        }
      }
    });
    if (!this.ec) {
      console.warn(
        '组件需绑定 ec 变量，例：<ec-canvas id="mychart-dom-bar" ' +
        'canvas-id="mychart-bar" ec="{
    
    { ec }}"></ec-canvas>'
      );
      return;
    }
    if (!this.ec.lazyLoad) {
      this.init();
    }
  },
  methods: {
    init(callback) {
      this.initByNewWay(callback);
    },
    initByNewWay(callback) {
      const query = Taro.createSelectorQuery();
      query
        .select(".ec-canvas")
        .fields({
          node: true,
          size: true
        })
        .exec(res => {
          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;

          const canvasDpr = Taro.getSystemInfoSync().pixelRatio;
          const canvasWidth = res[0].width;
          const canvasHeight = res[0].height;

          const ctx = canvasNode.getContext("2d");
          const canvas = new WxCanvas(ctx, this.canvasId, true, canvasNode);
          echarts.setCanvasCreator(() => {
            return canvas;
          });

          if (typeof callback === "function") {
            this.chart = callback(canvas, canvasWidth, canvasHeight, canvasDpr);
          } else if (typeof this.ec.onInit === "function") {
            this.chart = this.ec.onInit(
              canvas,
              canvasWidth,
              canvasHeight,
              canvasDpr
            );
          } else {
            this.triggerEvent('init', {
              canvas: canvas,
              width: canvasWidth,
              height: canvasHeight,
              dpr: canvasDpr
            })
          }
        });
    },
    canvasToTempFilePath(opt) {
      const query = Taro.createSelectorQuery().in(this);
      query
        .select(".ec-canvas")
        .fields({
          node: true,
          size: true
        })
        .exec(res => {
          const canvasNode = res[0].node;
          opt.canvas = canvasNode;
          Taro.canvasToTempFilePath(opt);
        });
    },
    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%;
}
</style>

五.封装e-chart.vue组件

<script lang=js>

扫描二维码关注公众号，回复： 15509703 查看本文章

使用js避免引入echarts.min.js报错，要求写声明文件.d.ts

不要使用setup语法糖 <script lang=js setup> 会报错

const ecCanvasRef = ref(null); vue3中使用ref获取组件实例声明与template中ref变量一致

expose vue3向外暴漏子组件方法,同<setup>语法糖里的defineExpose

<template>
    <ec-canvas ref="ecCanvasRef" :canvas-id="canvasId" :ec="ec"></ec-canvas>
</template>
  
<script lang="js">
/**
 * 自定义下载的echarts.min.js 文件  要使用需使用js,ts需要声明文件
 * 此组件不能使用setup语法糖，会报错的.
 */
import Taro, { useLoad } from "@tarojs/taro";
import * as echarts from './ec-canvas/echarts-5.4.1.min'
import EcCanvas from './ec-canvas/ec-canvas.vue'
import { ref, reactive } from "vue";
export default {
    components: {
        EcCanvas
    },
    props: {
        canvasId: {
            type: String,
            default: ''
        }
    },
    setup(props, { expose }) {
        const ec = reactive({
            lazyLoad: true
        })
        const ecCanvasRef = ref(null);

        const refresh = (options) => {
            if (!ecCanvasRef.value) {
                console.error('ecCanvas未获取到dom');
                return
            }
            ecCanvasRef.value?.init((canvas, width, height, canvasDpr) => {
                const chart = echarts.init(canvas, null, {
                    width: width,
                    height: height,
                    devicePixelRatio: canvasDpr
                })
                canvas.setChart(chart);
                chart.setOption(options);
                return chart;
            })
        }

        expose({
            refresh,
        })
        return {// 返回值会暴露给模板和其他的选项式 API 钩子
            ec, ecCanvasRef
        }
    },
}
</script>

六.使用封装的组件

<template>
    <view class="page">
        <view class="bar-chart">
            <EChart ref="barChat" canvas-id="bar-canvas" />
        </view>
        <button type="primary" :plain="true" @tap="onRefreshData">刷新数据</button>
    </view>
</template>
  
<script lang="ts" setup>
import Taro, { useReady } from "@tarojs/taro";
import { ref } from "vue";
import { randomArray } from '@/utils/array-util';
const colors = ref(["#3cb2ef", "#ffed65", "#FD665F", "#59d4d4", "#52d378", "#cc33cc", "#336666"]);
useReady(() => {
    initMultiBarChart();
})
const barChat = ref<any>();
const onRefreshData = () => {
    initMultiBarChart();
}
const initMultiBarChart = () => {
    let yData = [
        {
            Name: "收入",
            Value: randomArray(1000, 12)
        },
        {
            Name: "支出",
            Value: randomArray(992, 12)
        },
    ];
    const options = {
        tooltip: {
            trigger: "axis",
            axisPointer: {
                type: "cross",
                crossStyle: {
                    color: "#999",
                },
            },
        },
        grid: {
            y: 80,
            y2: 20,
            borderWidth: 1,
            // top: '90px',//内边距
            // left: '100px',
            // right: '0px',
            // bottom: '0px'
        },
        color: colors.value,
        legend: {
            data: ["收入", "支出"],
            left: "center",
            top: "1%",
        },
        xAxis: [
            {
                type: "category",
                data: ["1月",
                    "2月",
                    "3月",
                    "4月",
                    "5月",
                    "6月",
                    "7月",
                    "8月",
                    "9月",
                    "10月",
                    "11月",
                    "12月",],
                axisPointer: {
                    type: "shadow",
                },
            },
        ],
        yAxis: [
            {
                type: "value",
                name: "元",
                axisLabel: {
                    formatter: "{value}",
                },
            },
        ],
        series: yData.map((item) => {
            return {
                name: item.Name,
                type: "bar",
                barMaxWidth: 30,
                data: item.Value,
            };
        }),
    };
    Taro.nextTick(() => {
        barChat.value.refresh(options)
    })
}
</script>
  
<style lang="scss">
.bar-chart {
    width: 100%;
    min-height: 500px;
    flex: 1;
}
</style>

七.易错点

ec-canvas中使用Taro.createSelectorQuery()获取不到dom节点

const query = Taro.createSelectorQuery();
      query
        .select(".ec-canvas")
        .fields({
          node: true,
          size: true
        })
        .exec(res=>{
    
})

Taro.createSelectorQuery()获取节点必须在页面渲染完成后，否则获取到的是null;

在组件和页面里获取略有不同,Taro.createSelectorQuery().in(this)在页面里获取