react项目中预览pdf文件

最近需求，要在b端展示上传的pdf文件。实现方式有很多，记录一下我们最常用的pdf.js

//安装
"pdfjs-dist": "2.0.402"


//引入
import * as pdfjs from 'pdfjs-dist'
import * as pdfjsWorker from 'pdfjs-dist/build/pdf.worker.entry'



// 定义初始值
let pdfDoc = null;

  const [pdfParams, setPdfParams] = useState({

    pageNumber: 1, // 当前页

    total: 0,// 总页数

  });

// 预览pdf文档的地址
let pdfUrl = 'https://c.alisports.com/xxxxx/test.pdf'

// 加载
useEffect(() => {
    loadPdfFile(pdfUrl);
  }, [pdfUrl]);

// 初始化
const loadPdfFile = (pdfUrl) => {
    pdfjs.GlobalWorkerOptions.workerSrc = pdfjsWorker ;
    let url = pdfUrl ;
    pdfjs.getDocument(url).promise.then(async (doc) => {
      pdfDoc = doc
      getPdfPage(1)
      setPdfParams(s => ({
        ...s,
        total: doc.numPages
      }))
    })
  }

//加载页数
const getPdfPage = (number) => {
    pdfDoc.getPage(number).then(page => {
      const viewport = page.getViewport()
      const canvas = document.getElementById('pdf-render')
      const context = canvas.getContext('2d')
      canvas.width = viewport.viewBox[2]
      canvas.height = viewport.viewBox[3]
      viewport.width = viewport.viewBox[2]
      viewport.height = viewport.viewBox[3]
      canvas.style.width =  viewport.width // viewport.width为pdf文件的实际宽度
      canvas.style.height = viewport.height   // viewport.height为pdf文件的实际高度
  
      let renderContext = {
        canvasContext: context,
        viewport: viewport,
        // 这里transform的六个参数，使用的是transform中的Matrix(矩阵)
        transform: [1, 0, 0, -1, 0, viewport.height] // 默认填这个就好了
      }
      // 进行渲染
      page.render(renderContext)
    })
  }


// dom结构
<canvas id="pdf-render" ></canvas>