在electron下實現PDF在線預覽功能

時間 2019-11-30

標籤 electron 實現 pdf 在線預覽功能简体版

原文原文鏈接

因爲公司業務的開發須要，須要實如今electron上實現PDF的在線預覽功能。electron 3.x版本後就不在支持PDF的預覽功能了，官方給的解釋是因爲人手不夠將再也不支持PDF預覽功能(也是醉了)，在通過一番調研結合大佬們的經驗實現了PDF的在在線預覽功能javascript

實現方式1、

下載pdfjs-distcss
將下好的文件放入static文件目錄下html

在electron的主線程中經過渲染線程與主線程之間的通訊獲取viewer.html文件位置vue

// 監聽獲取viewer.html文件位置、
function getUrl(win) {
  const filePath = process.env.NODE_ENV === 'development' ? `${__static}\\pdfjs\\web\\viewer.html` : path.resolve(__dirname, '../../../static/pdfjs/web/viewer.html')
  win.webContents.send('recieve', filePath)
}
// pdf預覽獲取viewer.html文件位置
    ipcMain.on('getUrl', () => getUrl(win))
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在pdf.vue中寫java

<template>
   <iframe
        :src="base + '?file=' + url"
        :width="width"
        :height="height"
        class="iframe-placeholder"></iframe>
</template>
<script>
import { ipcRenderer } from 'electron' // eslint-disable-line

export default {
  props: {
    url: {
      type: String,
      default: '',
    },
    width: {
      type: Number,
      default: 750
    },
    height: {
      type: Number,
      default: 600
    },
  },
  data() {
    return {
      preview: false,
      base: '',
    }
  },
  computed: {
    // 講義文件名
    name() {
      const uri = decodeURI(this.url)
      const arr = uri.split('/')
      const len = arr.length
      return arr[len - 1]
    },
  },
  created() {
    // 獲取viewer.html的位置
    ipcRenderer.send('getUrl')
  },
  mounted() {
    ipcRenderer.on('recieve', (e, arg) => {
      console.log('文件路徑', arg)
      this.base = arg
    })
  }
}
</script>

<style lang="scss" scoped>
.wrapper {
  .info {
    width: 200px;
  }
  .iframe-placeholder {
    background: url('../../../assets/loading.svg') no-repeat 50% 50%;
  }
}
</style>

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在須要引入的地方引用便可webpack

問題git

樣式比較醜，可是能夠實現PDF的分頁和打印的功能，且在打完包後文件比較大web

實現方式2、

下載npm pdfjs-dist 包npm

// npm的下載方式
npm i pdfjs-dist
// yarn 的下載方式
yarn add pdfjs-dist
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在webpack的配置中寫入canvas

entry: {
    renderer: path.join(__dirname, '../src/renderer/main.js'),
    'pdf.worker': 'pdfjs-dist/build/pdf.worker.entry',
  },
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在pdf.vue中寫入

<template>
  <el-dialog
    :visible.sync="pdfjsView"
    title=""
    width="55%"
    class="cpdf"
    append-to-body
    @close="pdfurl = null">
    <div v-loading="loading" v-if="pdfurl" class="center" style="height:600px">
      <canvas v-for="data in canvasData" :key="data" :id="'the-canvas-'+data" class="canvasstyle"></canvas>
    </div>
    <div v-else style="font-size:18px;text-align:center;font-weight:900">
      沒有PDF文件能夠預覽
    </div>
    <span slot="footer">
      <el-button @click="pdfjsView = false">取 消</el-button>
      <el-button type="primary" @click="pdfjsView = false">確 定</el-button>
    </span>
  </el-dialog>
</template>

<script type="text/ecmascript-6">
import PDFJS from 'pdfjs-dist'

export default {
  name: 'CPdf',
  components: {},
  data() {
    return {
      pdfDoc: null, // pdfjs 生成的對象
      pageNum: 1, //
      pageRendering: false,
      pageNumPending: null,
      scale: 1.2, // 放大倍數
      page_num: 0, // 當前頁數
      page_count: 0, // 總頁數
      maxscale: 2, // 最大放大倍數
      minscale: 0.8, // 最小放大倍數
      canvasData: [],
      pdfjsView: false,
      pdfurl: null,
      loading: false
    }
  },
  methods: {
    renderPage(num) {
      // 渲染pdf
      const vm = this
      this.pageRendering = true
      const canvas = document.getElementById(`the-canvas-${num}`)
      // Using promise to fetch the page
      this.pdfDoc.getPage(num).then((page) => {
        const viewport = page.getViewport(vm.scale)
        // alert(vm.canvas.height)
        canvas.height = viewport.height
        canvas.width = viewport.width

        // Render PDF page into canvas context
        const renderContext = {
          //   canvasContext: vm.ctx,
          canvasContext: canvas.getContext('2d'),
          viewport
        }
        const renderTask = page.render(renderContext)

        // Wait for rendering to finish
        renderTask.promise.then(() => {
          vm.pageRendering = false
          if (vm.pageNumPending !== null) {
            // New page rendering is pending
            vm.renderPage(vm.pageNumPending)
            vm.pageNumPending = null
          }
        })
      })
      vm.page_num = vm.pageNum
    },
    getUrl(url) {
      this.pdfurl = url
      this.pdfjsView = true
      this.showPDf()
    },
    showPDf() {
      const vm = this
      this.loading = true
      vm.canvasData = []
      // PDFJS.workerSrc = '../../../static/PDF/pdf.worker.min.js'
      PDFJS.getDocument(vm.pdfurl)
        .then((pdfDoc_) => {
        // 初始化pdf
          vm.pdfDoc = pdfDoc_
          vm.page_count = vm.pdfDoc.numPages
          for (let i = 0; i < vm.page_count; i += 1) {
            vm.canvasData.push(i + 1)
          }
          return pdfDoc_
        })
        .then((pdfDoc_) => {
        // 初始化pdf
          vm.pdfDoc = pdfDoc_
          vm.page_count = vm.pdfDoc.numPages
          for (let i = 0; i < vm.page_count; i += 1) {
            vm.renderPage(i + 1)
          }
          vm.loading = false
        })
    }
  },
  computed: {},
  mounted() {}
}
</script>

<style lang="scss" scoped type="text/css">
.cpdf {
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 99999;
  display: flex;
  justify-content: center;
  align-items: center;
  .center {
    text-align: center;
    height: 100%;
    overflow: auto;
    padding-top: 20px;
    .contor {
      margin-bottom: 10px;
    }
  }
  .page-foot {
    position: fixed;
    left: 0px;
    bottom: 0px;
    width: 100%;
    height: 56px;
    line-height: 56px;
    background-color: #fff;
    text-align: center;
    z-index: 10;
    .foot-button {
        display: inline-block;
        height: 56px;
        position: relative;
        top: -22px;
        left: 20px;
    }
  }
}
</style>
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