Taro+Vue3 小程序引入echarts表

背景：根据需求在一个报告界面需要展示不同的echarts表来使数据更友好的显示。

效果如下：

一.taro支持echarts

官方说明：Taro 文档支持引用小程序端第三方组件库

物料文档：Taro 物料市场 | 让每一个轮子产生价值

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;
注意点：折线图中如果需要显示面积图的平均线，则要下载对应的标线组件。

经过三、四步骤之后会得到两个文件，目录结构如下：

四.封装组件ec-canvas.vue

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

<script lang="js">
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(`.${this.canvasId}`) // 根据canvasId动态获取不同的echarts图表
        .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%;
  min-height: 400rpx;
  flex: 1;
}
</style>

五.封装e-chart.vue组件

<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

此时封装的目录结构如下：

子组件：

<template>
  <view class="cards bg-white mx-sm mt-mm">
    <view class="text-center pt-xs pb-mm">
      <text class="text-md text-dark ml-sm">借贷分析</text>
    </view>
   
    <cover-view class="container-echarts">
      <e-chart ref="barChat" canvas-id="bar-canvas" />
    </cover-view>
  </view>
</template>
<script lang="ts">
export default { name: 'loanAnalysis' };
</script>

<script lang="ts" setup>
import Taro, { useReady } from '@tarojs/taro';
import { ref } from 'vue';
import EChart from '../components/echarts/e-chart.vue';
import { getLoanView } from '@/service/report';
import { MoneyNoUnitText, FormatThousand } from '@/units/currency';

const components = { 'e-chart': EChart };

const props = defineProps({
  params: { type: Object, required: true }
});

useReady(() => {
  initMultiBarChart();
});
const barChat = ref<any>();
let loanAmount = ref<number>();
let repaymentLoanAmount = ref<number>();
let prototypeOption = {
  grid: { left: 14, right: 18, bottom: 8, top: 40, containLabel: true },
  legend: { show: false },
  color: ['#40a9ff', '#FF5652'],
  xAxis: [
    {
      type: 'category',
      data: [],
      axisLabel: { fontSize: 10, color: 'rgba(0, 0, 0, 0.56)' },
      axisLine: { show: false },
      axisTick: { show: false }
    }
  ],
  yAxis: [
    {
      type: 'value',
      name: '万元',
      nameTextStyle: { padding: [0, 40, 0, 0], color: 'rgba(0,0,0,0.56)' },
      axisLabel: { fontSize: 10, color: 'rgba(0, 0, 0, 0.56)' },
      axisLine: { show: false },
      axisTick: { show: false },
      splitNumber: 2
    }
  ],
  series: [
    {
      name: '贷款、借款流入',
      type: 'bar',
      data: [],
      barMaxWidth: 12,
      barMinHeight: 1,
      stack: 'cr',
      itemStyle: {
        barBorderRadius: [0, 2, 0, 0]
      }
    },
    {
      name: '偿还贷款、借款',
      type: 'bar',
      data: [],
      barMaxWidth: 12,
      barMinHeight: 1,
      stack: 'cr',
      itemStyle: {
        barBorderRadius: [0, 0, 0, 2]
      }
    }
  ]
};

const initMultiBarChart = () => {
  getLoanView(props.params).then(res => {
    if (res) {
      loanAmount.value = MoneyNoUnitText(res.loanAmount || 0);
      repaymentLoanAmount.value = MoneyNoUnitText(res.repaymentLoanAmount || 0);

      prototypeOption.xAxis[0].data = res.list.map(
        i => i.dateId.toString().slice(2, 4) + '.' + i.dateId.toString().slice(4)
      );
      prototypeOption.yAxis[0].axisLabel = {
        formatter: (v: any) => (Math.abs(v) > 0 ? FormatThousand(parseInt(v / 10000), 0) : v),
        color: 'rgba(0, 0, 0, 0.56)'
      };
      prototypeOption.series[0].data = res.list.map(i => (i.loanAmount > 0 ? i.loanAmount : null));
      prototypeOption.series[1].data = res.list.map(i =>
        i.repaymentLoanAmount > 0 ? -i.repaymentLoanAmount : null
      );

      Taro.nextTick(() => {
        barChat.value.refresh(prototypeOption);
      });
    }
  });
};
</script>

<style>
.container-echarts {
  height: 400rpx;
  width: 100%;
}
</style>

父组件引用子组件：

import loanAnalysis from './loan-analysis.vue';

 <loan-analysis :params="params"></loan-analysis>



【 问题描述 】在小程序使用echarts，图表展示出来之后不跟随页面滚动，浮在最上方。
【 问题原因 】布局中含有position:fixed或absulote的元素，导致echarts图表无法滑动。
官方文件说明：canvas为原生组件故有一下的性质： bash 由于原生组件脱离在 WebView 
渲染流程外，因此在使用时有以下限制： 组件的层级是最高的，所以页面中的其他组件无论设置
 z-index 为多少，都无法盖在原生组件上。 后插入的原生组件可以覆盖之前的原生组件。 
原生组件还无法在 scroll-view、swiper、picker-view、movable-view 中使用。 
部分CSS样式无法应用于原生组件，例如： 无法对原生组件设置 CSS 动画 无法定义
原生组件为 position: fixed 不能在父级节点使用 overflow:hidden 来裁剪
原生组件的显示区域
【 解决方法 】所有父级元素（有包含ec-canvas的所有view元素）的position不可为
fixed或absulote，将其改为其他，另外兄弟元素可以为position:absulote或fixed，
否在还是会有重叠

原文链接：https://blog.csdn.net/samscat/article/details/126182735

参考博文：Taro3+Vue3使用echarts_taro使用echarts_江渚清沨的博客-CSDN博客