效果：

1. 下载依赖包

   npm i bpmn-js bpmn-js-properties-panel camunda-bpmn-moddle

   "bpmn-js": "^10.3.0",
   "bpmn-js-properties-panel": "^1.11.2",
   "camunda-bpmn-moddle": "^7.0.1",

2. 构建bpmn界面

   // 样式
   import 'bpmn-js/dist/assets/diagram-js.css'
   import 'bpmn-js/dist/assets/bpmn-font/css/bpmn.css'
   import 'bpmn-js/dist/assets/bpmn-js.css'
   import 'bpmn-js/dist/assets/bpmn-font/css/bpmn-codes.css'
   import 'bpmn-js/dist/assets/bpmn-font/css/bpmn-embedded.css'
   import 'bpmn-js-properties-panel/dist/assets/element-templates.css';
   import 'bpmn-js-properties-panel/dist/assets/properties-panel.css';
   // bpmn构建器
   import BpmnModeler from 'bpmn-js/lib/Modeler.js' // 引入 bpmn-js
   // 初始化xml
   import diagramXML from './bpmnXML'
   // 汉化
   import zh from './zh'
   // 构建模块
   import {
   BpmnPropertiesPanelModule,
   BpmnPropertiesProviderModule,
   CamundaPlatformPropertiesProviderModule,
   CloudElementTemplatesPropertiesProviderModule
   } from 'bpmn-js-properties-panel'
   import camundaModdleDescriptor from 'camunda-bpmn-moddle/resources/camunda.json'

   // html
   
   // js
   mounted() {
   this.bpmnModeler = new BpmnModeler({
   container: this.$refs.bpmn,
   propertiesPanel: {
   parent: this.$refs.bpmnPanel
   },
   additionalModules: [
   BpmnPropertiesPanelModule,
   BpmnPropertiesProviderModule,
   CamundaPlatformPropertiesProviderModule,
   CloudElementTemplatesPropertiesProviderModule,
   { translate: [ 'value', this.customTranslate ] } // 汉化
   ],
   moddleExtensions: {
   camunda: camundaModdleDescriptor
   }
   })
   this.createNewDiagram()
   }

   // 方法
   customTranslate(template: any, replacements: any) {
   replacements = replacements || {};
   template = (zh as Record)[template] || template;
   return template.replace(/{([^}]+)}/g, function(_: any, key: any) {
   return replacements[key] || '{' + key + '}';
   });
   }
   createNewDiagram() {
   this.openDiagram(diagramXML);
   }
   async openDiagram(xml: string) {
   this.bpmnModeler.importXML(xml);
   }

css

// css
.app-container {
  background-color: white;
  position: relative;
  height: 100vh;
}
.buttons{
  position: absolute;
  bottom: 30px;
  display: flex;
  left: 50px;
  padding: 0;
  margin: 0;
  list-style: none;
  .item {
    margin-right: 10px;
  }
  .download button {
    padding: 0;
    a {
      padding: 8px 15px;
    }
  }
}
 .bpmn-main-box {
  width:100%;
  height:100%;
  display: flex;
 }
 .bpmn-container {
    width: 100%;
    height: 100%;
    background: url('data:image/svg+xml;base64,PHN2ZyB3aWR0aD0iNDAiIGhlaWdodD0iNDAiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+PGRlZnM+PHBhdHRlcm4gaWQ9ImEiIHdpZHRoPSI0MCIgaGVpZ2h0PSI0MCIgcGF0dGVyblVuaXRzPSJ1c2VyU3BhY2VPblVzZSI+PHBhdGggZD0iTTAgMTBoNDBNMTAgMHY0ME0wIDIwaDQwTTIwIDB2NDBNMCAzMGg0ME0zMCAwdjQwIiBmaWxsPSJub25lIiBzdHJva2U9IiNlMGUwZTAiIG9wYWNpdHk9Ii4yIi8+PHBhdGggZD0iTTQwIDBIMHY0MCIgZmlsbD0ibm9uZSIgc3Ryb2tlPSIjZTBlMGUwIi8+PC9wYXR0ZXJuPjwvZGVmcz48cmVjdCB3aWR0aD0iMTAwJSIgaGVpZ2h0PSIxMDAlIiBmaWxsPSJ1cmwoI2EpIi8+PC9zdmc+')
      repeat !important;
 }
 #js-properties-panel {
  border: 1px solid rgba(0,0,0,0.1);
  width: 250px;
 }

zh.ts（部分代码）

export default {
  'Id': '编号',
  'Name': '名称',
  'General': '常规',
  'Details': '详情',
  'Message Name': '消息名称',
  'Message': '消息',
  'Initiator': '创建者',
  'Asynchronous continuations': '持续异步',
  'Asynchronous before': '异步前',
  'Asynchronous after': '异步后',
  'Job configuration': '工作配置',
  'Exclusive': '排除',
  'Job Priority': '工作优先级',
  'Retry Time Cycle': '重试时间周期',
  'Documentation': '文档',
  'Element Documentation': '元素文档',
  'History Configuration': '历史配置',
  'History Time To Live': '历史的生存时间',
  'Forms': '表单',
}

bpmnXML.ts

export default `<?xml version="1.0" encoding="UTF-8"?>
<bpmn2:definitions
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:bpmn2="http://www.omg.org/spec/BPMN/20100524/MODEL"
xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI"
xmlns:dc="http://www.omg.org/spec/DD/20100524/DC"
xmlns:di="http://www.omg.org/spec/DD/20100524/DI"
xsi:schemaLocation="http://www.omg.org/spec/BPMN/20100524/MODEL BPMN20.xsd"
id="sample-diagram"
targetNamespace="http://bpmn.io/schema/bpmn">
  <bpmn2:process id="Process_1" isExecutable="false">
  </bpmn2:process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_1">
      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
        <dc:Bounds height="36.0" width="36.0" x="412.0" y="240.0"/>
      </bpmndi:BPMNShape>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn2:definitions>`

1. 添加操作按钮

事件方法

let bpmnModeler: any = null
let perviewXMLShow = false
let perviewSVGShow = false
let perviewXMLStr = ''
let perviewSVGData = ''
// 文件上传
fileChange() {
  const fileElement = this.$refs.file as HTMLInputElement
  if (fileElement && fileElement.files) {
    const file = fileElement.files[0]
    const fileReader = new FileReader();
    (this.$refs.file as HTMLInputElement).value = ''
    fileReader.onload = (e: any) => {
      this.bpmnModeler.importXML(e.target.result)
    }
    fileReader.readAsText(file);
  }
}
// 点击文件上传
upload() {
  this.getHTMLElementByRef('file').click()
}
// 新建
newCreateDoc() {
  this.bpmnModeler.importXML(diagramXML)
}
// 下载XML
async downloadLinkClick() {
  const downloadLink = this.$refs.downloadLink as HTMLElement
  try {
    const { xml } = await this.bpmnModeler.saveXML({ format: true });
    this.setEncoded(downloadLink, 'diagram.bpmn', xml);
  } catch (error) {
    this.toast.error('下载失败，请重试')
  }
}
// 下载SVG
async downloadSvg() {
  const downloadSvgLink = this.$refs.downloadSvg as HTMLElement
  try {
    const { svg } = await this.bpmnModeler.saveSVG();
    this.setEncoded(downloadSvgLink, 'diagram.svg', svg);
  } catch (error) {
    this.toast.error('下载失败，请重试')
  }
}
// XML预览
async perviewXML() {
  try {
    const { xml } = await this.bpmnModeler.saveXML({ format: true });
    this.perviewXMLStr = xml
    this.perviewXMLShow = true
  } catch (error) {
    this.toast.error('预览失败，请重试')
  }
}
// SVG预览
async perviewSVG() {
  try {
    const { svg } = await this.bpmnModeler.saveSVG();
    this.perviewSVGData = svg
    this.perviewSVGShow = true
  } catch (error) {
    this.toast.error('预览失败，请重试')
  }
}

// 设置数据
setEncoded(link: HTMLElement, name: string, data: any) {
  const encodedData = encodeURIComponent(data);
  if (data) {
    link.className += ('active')
    link.setAttribute('href', 'data:application/bpmn20-xml;charset=UTF-8,' + encodedData)
    link.setAttribute('download', name)
  } else {
    link.className.replace('active', '')
  }
}