vue3 实现pdf预览

需要下载pdfjs-dist

<template>
    <a-modal class="fill-modal" v-model:open="state.visible" :title="state.modalTitle" width="50%" @cancel="handleCancel">
        <div class="preview-btns-posi">
            <a-button type="primary" @click="exportBtn" :loading="state.downLoading">下载</a-button>
            <a-button @click="handleCancel" type="primary">返回</a-button>
        </div>
        <div class="interviewVideo_main" id="videoContainer">
            <!--此处根据pdf的页数动态生成相应数量的canvas画布-->
            <canvas v-show="state.show" v-for="pageIndex in pdfPages" :id="`pdf-canvas-` + pageIndex" :key="pageIndex"
                style="display: block;width:100%;" class="canvas"></canvas>
        </div>
        <template #footer></template>
    </a-modal>
</template>
<script lang="ts" setup>
import { ref, reactive, nextTick } from "vue";
import * as pdfjsLib from "pdfjs-dist/build/pdf.js";

import * as workerSrc from 'pdfjs-dist/build/pdf.worker.min.js'
import { message } from "ant-design-vue";
import { downloadBlobAsync } from "@/lib/tool";


let pdfPages = ref(0); // pdf文件的页数
let pdfDoc: any = reactive({})
let pdfScale = ref(1.0); // 缩放比例
const state: any = reactive({
    visible: false,
    downLoading: false,
    modalTitle: '预览文件',
    show: false
})
const props = defineProps<{
    file: {
        previewPath: string,
        originalFileName: string,
        path: string,
    }
}>()

//调用loadFile方法
//获取pdf文档流与pdf文件的页数
const loadFile = async (url: string) => {
    try {
        pdfjsLib.GlobalWorkerOptions.workerSrc = workerSrc;
        const loadingTask = pdfjsLib.getDocument(url);
        loadingTask.promise.then((pdf: any) => {
            state.show = true;
            pdfDoc = pdf;
            pdfPages.value = pdf.numPages;
            nextTick(() => {
                renderPage(1);
            });
        }).catch((err: any) => {
            console.error(err);
            pdfDoc = null
            state.show = false
        });
    } catch (error) {
        console.error(error)
    }
};
//渲染pdf文件
const renderPage = (num: number) => {
    pdfDoc?.getPage(num).then((page: any) => {
        const canvasId = "pdf-canvas-" + num;
        const canvas = <any>document.getElementById(canvasId);
        const ctx = canvas.getContext("2d");
        const dpr = window.devicePixelRatio || 1;
        const bsr =
            ctx.webkitBackingStorePixelRatio ||
            ctx.mozBackingStorePixelRatio ||
            ctx.msBackingStorePixelRatio ||
            ctx.oBackingStorePixelRatio ||
            ctx.backingStorePixelRatio ||
            1;
        const ratio = dpr / bsr;
        const viewport = page.getViewport({ scale: pdfScale.value });
        canvas.width = viewport.width * ratio;
        canvas.height = viewport.height * ratio;
        canvas.style.width = viewport.width + "px";
        canvas.style.height = viewport.height + "px";
        ctx.setTransform(ratio, 0, 0, ratio, 0, 0);
        const renderContext = {
            canvasContext: ctx,
            viewport: viewport,
        };
        page.render(renderContext);
        if (num < pdfPages.value) {
            renderPage(num + 1);
        }
    });
};
function openModal() {
    state.visible = true;
    nextTick(() => {
        loadFile(props.file.previewPath);
    })
}
function handleCancel() {
    state.visible = false;
}
async function exportBtn() {
    try {
        state.downLoading = true
        if (!props.file?.path) {
            message.warning(`无地址，可供下载`)
            return;
        }
        await downloadBlobAsync(props.file?.path, props.file?.originalFileName, true)
    } catch (error: any) {
        message.error(error)
    } finally {
        state.downLoading = false
    }
}

defineExpose({
    openModal
})
</script>
<style>
#videoContainer {
    height: 500px;
    width: 100%;
    overflow: auto;
    .canvas {
        width: 80% !important;
        margin: 0 auto;
    }
}

.preview-btns-posi {
    position: absolute;
    top: 10px;
    right: 50px;
}
</style>

/**下载文件 */
export const downloadBlobAsync = (blob: Blob | string, fileName: string, isUrl = false) => {
  return new Promise<void>((resolve, reject) => {
    try {
      //对于<a>标签，只有 Firefox 和 Chrome（内核） 支持 download 属性
      //IE10以上支持blob但是依然不支持download
      if ('download' in document.createElement('a')) {
        //支持a标签download的浏览器
        const link = document.createElement('a'); //创建a标签
        link.download = fileName; //a标签添加属性
        link.style.display = 'none';
        link.href = isUrl ? blob as string : URL.createObjectURL(blob as Blob);
        document.body.appendChild(link);
        link.click(); //执行下载
        URL.revokeObjectURL(link.href); //释放url
        document.body.removeChild(link); //释放标签
      } else {
        //其他浏览器
        (navigator as any)?.msSaveBlob(blob, fileName);
      }
    } catch (error) {
      console.log(error)
      reject(error);
    } finally {
      setTimeout(() => {
        resolve()
      }, 500)
    }
  })
};