做网站图片多大效果好的关键词如何优化
需求：pdf预览，并且可以选中pdf的内容进行复制。
在ruoyi的vue前端项目中用到，参考了网上不少文章，因为大部分没给具体的pdf.js版本，导致运行过程中报各种api 错误，经过尝试以下版本可用，故记录一下：
安装依赖:
npm install pdfjs-dist@2.0.943vue 页面
<template><div><button @click="scalBig">放大</button><button @click="scalSmall">缩小</button><p>页码：{{ `${pageNo}/${totals.length}` }}</p><div class="drag-box" id="dragBox" @scroll="scrollfun($event)"><el-scrollbar><div class="wrapper" id="pdf-container"><div v-for="item in totals" :id="`page-${item}`" :key="item" class="pdf-box"><canvas :id="'canvas-pdf-' + item" class="canvas-pdf"></canvas></div></div></el-scrollbar></div></div>
</template><script>
const PDFJS = require('pdfjs-dist')
PDFJS.GlobalWorkerOptions.workerSrc = require('pdfjs-dist/build/pdf.worker.min')
import { TextLayerBuilder } from 'pdfjs-dist/web/pdf_viewer'
import 'pdfjs-dist/web/pdf_viewer.css'
import axios from 'axios';
export default {name: 'showPdf',// props: ['pdfUrl'],data() {return {scale: 1.4,totals: [],pageNo: 1,viewHeight: 0,pdfUrl: 'http://localhost/a.pdf'}},mounted() {this.renderPdf(this.scale)},watch: {scale(val) {this.totals = []this.renderPdf(val)}},methods: {async downloadAndConvertToUint8Array(pdfUrl) {// 使用 axios 发送 GET 请求获取 PDF 文件数据const response = await axios({url: pdfUrl,method: 'GET',responseType: 'arraybuffer', // 设置响应类型为 arraybuffer});// 将 arraybuffer 转换为 Uint8Arrayconst uint8Array = new Uint8Array(response.data);return uint8Array;},renderPdf(scale) {this.downloadAndConvertToUint8Array(this.pdfUrl).then((uint8Array) => {console.log(uint8Array);// 现在你可以用这个 Uint8Array 对象进行进一步处理，例如传递给PDF.js库渲染PDF// 当 PDF 地址为跨域时，pdf 应该已流的形式传输，否则会出现pdf损坏无法展示PDFJS.getDocument(uint8Array).then(pdf => {// 得到PDF的总的页数let totalPage = pdf.numPageslet idName = 'canvas-pdf-'// 根据总的页数创建相同数量的canvasthis.createCanvas(totalPage, idName)for (let i = 1; i <= totalPage; i++) {pdf.getPage(i).then((page) => {let pageDiv = document.getElementById(`page-${i}`)let viewport = page.getViewport(scale)let canvas = document.getElementById(idName + i)let context = canvas.getContext('2d')canvas.height = viewport.heightcanvas.width = viewport.widththis.viewHeight = viewport.heightlet renderContext = {canvasContext: context,viewport}// 如果你只是展示pdf而不需要复制pdf内容功能，则可以这样写render// page.render(renderContext) 如果你需要复制则像下面那样写利用text-layerpage.render(renderContext).then(() => {return page.getTextContent()}).then((textContent) => {// 创建文本图层divconst textLayerDiv = document.createElement('div')textLayerDiv.setAttribute('class', 'textLayer')// 将文本图层div添加至每页pdf的div中pageDiv.appendChild(textLayerDiv)// 创建新的TextLayerBuilder实例let textLayer = new TextLayerBuilder({textLayerDiv: textLayerDiv,pageIndex: page.pageIndex,viewport: viewport})textLayer.setTextContent(textContent)textLayer.render()})})}})}).catch((error) => {console.error('Error downloading or converting the PDF:', error);});},createCanvas(totalPages) {for (let i = 1; i <= totalPages; i++) {this.totals.push(i)}},// 分页scrollfun(e) {let scrollTop = e.target.scrollTopif (scrollTop === 0) {this.pageNo = 1} else {this.pageNo = Math.ceil(scrollTop / this.viewHeight)}},// 放大scalBig() {this.scale = this.scale + 0.1},// 缩小scalSmall() {if (this.scale > 1.2) {this.scale = this.scale - 0.1}}}
}
</script><style scoped lang="scss">
.drag-box {height: 800px;
}.pdf-box {position: relative;
}.el-scrollbar__wrap {overflow-x: hidden;
}
</style>运行效果：
