通过pdfjs-dist讲pdf转为图片进行预览的方式
存在失真的问题

npm i pdfjs-dist -S

<template>
  <el-dialog :title="title" :visible.sync="dialogVisible" width="60%" :before-close="handleClose" append-to-body>
    <canvas ref="canvas" v-if="reFresh"></canvas>
    <span v-else>暂无数据</span>
       <span slot="footer" class="dialog-footer">
      <span class="jumpBtn">
        <span style="margin-right:10px">共{{max_pageNum}}页</span>
        前往
        <el-input v-model="jumpNum" v-if="fileURL" @change="Page(2)"></el-input>页
      </span>
      <el-button @click="Page(0)" v-if="fileURL">上一页</el-button>
      <el-button @click="Page(1)" v-if="fileURL">下一页</el-button>
      <el-button @click="dialogVisible = false">关 闭</el-button>
    </span>
  </el-dialog>
</template>

<script>
import pdfJs from "pdfjs-dist";
import pdfjsLib from "pdfjs-dist/build/pdf.worker";
export default {
  props: {
    title: {
      type: String,
      default: '在线预览'
    },
  },
  data() {
    return {
      imgUrl: '',
      pageNum: 1,
      max_pageNum: 0,
      dialogVisible: false,
      fileURL: '',
      reFresh: true
    }
  },
  watch: {
    fileURL() {
      this.reFresh = false
      this.$nextTick(() => {
        this.reFresh = true
      })
    }
  },
  methods: {
    init(){
      this.dialogVisible=true;
    },
    handleClose() {
      this.dialogVisible = false
      this.$emit('close')
    },
    handleOpen(val) {
      this.dialogVisible = true
      this.fileURL = val
      this.showPdf(1)
    },
    Page(val) {
      if (val == 0) {
        this.pageNum > 1 ? this.showPdf(this.pageNum - 1) : "";
      } else if (val == 1) {
        this.pageNum < this.max_pageNum
          ? this.showPdf(this.pageNum + 1)
          : this.$message({ type: "warning", message: "已经是最一页" });
      } else {
        this.jumpNum <= this.max_pageNum && this.jumpNum > 0
          ? this.showPdf(this.jumpNum)
          : this.$message({ type: "warning", message: "不存在该页" });
      }
    },
    showPdf(num) {
      let _this = this;
      let imgArr = [];
      pdfJs.workerSrc = 'pdf.worker.js';
      let loadingTask = pdfJs.getDocument(this.fileURL);
      loadingTask.promise.then(function (pdf) {
        _this.max_pageNum = pdf.numPages;
        _this.pageNum = num
        pdf.getPage(Number(num)).then(function (page) {
          let viewport = page.getViewport(2.0);
          let canvas = _this.$refs.canvas
          let context = canvas.getContext('2d');
          canvas.height = viewport.height
          canvas.width = viewport.width
          let renderContext = {
            canvasContext: context, viewport: viewport
          };
          let renderTask = page.render(renderContext);
          context.clearRect(0, 0, canvas.width, canvas.height);
          renderTask.then(function () {
              canvas.toDataURL('image/jpeg'); //转换为base64
          });
        });
      }, function (reason) {
        console.error(reason);
      });

      function isEmpty(arr) {
        for (let i = 0; i < arr.length; i++) {
          if (!arr[i])
            return true;
        }
        return false;
      }
    }
  }
}

</script>
<style lang="scss" scoped>
>>> .el-dialog__body {
  text-align: center;
}
.jumpBtn {
  >>> .el-input{
    width: 60px;
  }
}
</style> >

使用

// 引入组件
import showPdf from '@/components/pdfView/index.vue'
//注册
components: { showPdf}
<showPdf ref="showPdf"></showPdf>

// 打开预览，传入pdf的完整路径
 this.$refs.showPdf.handleOpen(this.applyURL)