emis-frontend/src/utils/pdfUtils.js

import { degrees, PDFDocument, rgb, StandardFonts } from 'pdf-lib';
import axios from "axios";
import Buffer from 'vue-buffer'

/**
 * 浏览器打开新页签预览pdf
 * blob（必选）: pdf文件信息（Blob对象）【Blob】
 * docTitle（可选）: 浏览器打开新页签的title  【String】
 * isAddWatermark（可选，默认为false）: 是否需要添加水印 【Boolean】
 * watermark（必选）：水印信息 【Object: { type: string, text: string, image:{ bytes: ArrayBuffer, imageType: string } }】
 * watermark.type（可选）：类型 可选值：text、image、canvas
 * watermark.text（watermark.type为image时不填，否则必填）：水印文本。注意：如果watermark.type值为text，text取值仅支持拉丁字母中的218个字符。详见：https://www.npmjs.com/package/pdf-lib
 * watermark.image（watermark.type为image时必填，否则不填）：水印图片
 * watermark.image.bytes：图片ArrayBuffer
 * watermark.image.imageType：图片类型。可选值：png、jpg
 * Edit By WFT
 */
export default class PdfUtils {
  constructor() {
    // { blob, docTitle, isAddWatermark = false, watermark: { type = 'text', text = 'WFT', image } }
    const _self = this
    // if(!blob) {
    //   return console.error('[PDF Blob Is a required parameter]')
    // }
    // if(!isAddWatermark) { // 不添加水印
    //   _self.preView(blob, docTitle)
    // } else {
    //   let bytes,imageType
    //   if(type == 'image') {
    //     if(!image) {
    //       return console.error('["image" Is a required parameter]')
    //     }
    //     bytes = image.bytes
    //     imageType = image.imageType
    //   }
    //   const map = {
    //     'text': _self.addTextWatermark.bind(_self),
    //     'image': _self.addImageWatermark.bind(_self),
    //     'canvas': _self.addCanvasWatermark.bind(_self)
    //   }
    //   blob.arrayBuffer().then(async buffer => {
    //     const existingPdfBytes = buffer
    //     const pdfDoc = await PDFDocument.load(existingPdfBytes)
    //     let params
    //     if(type == 'text') params = { pdfDoc, text, docTitle }
    //     if(type == 'image') params = { pdfDoc, bytes, imageType, docTitle }
    //     if(type == 'canvas') params = { pdfDoc, text, docTitle }
    //     map[type](params)
    //   }).catch(e => console.error('[Preview Pdf Error]:', e))
    // }
  }

  // 添加 Text 水印
  async addTextWatermark({ pdfDoc, text, docTitle }) {
    // console.log(StandardFonts, 'StandardFonts-->>') // 字体
    const helveticaFont = await pdfDoc.embedFont(StandardFonts.Helvetica)
    const pages = pdfDoc.getPages()
    for(let i = 0; i < pages.length; i++) {
      let page = pages[i]
      let { width, height } = page.getSize()
      for(let i = 0; i < 6; i++) {
        for(let j = 0; j < 6; j++) {
          page.drawText(text, {
            x: j * 100,
            y: height / 5 + i * 100,
            size: 30,
            font: helveticaFont,
            color: rgb(0.95, 0.1, 0.1),
            opacity: 0.2,
            rotate: degrees(-35),
          })
        }
      }
    }
    // 序列化为字节
    const pdfBytes = await pdfDoc.save()
    this.preView(pdfBytes, docTitle)
  }

  // 添加 image 水印
  async addImageWatermark({ pdfDoc, bytes, imageType, docTitle }) {
    // 嵌入JPG图像字节和PNG图像字节
    let image
    const maps = {
      'jpg': pdfDoc.embedJpg.bind(pdfDoc),
      'png': pdfDoc.embedPng.bind(pdfDoc)
    }
    image = await maps[imageType](bytes)
    // 将JPG图像的宽度/高度缩小到原始大小的50%
    const dims = image.scale(0.5)
    const pages = pdfDoc.getPages()
    for(let i = 0; i < pages.length; i++) {
      let page = pages[i]
      let { width, height } = page.getSize()
      for(let i = 0; i < 6; i++) {
        for(let j = 0; j < 6; j++) {
          page.drawImage(image, {
            x: width / 5 - dims.width / 2 + j * 100,
            y: height / 5 - dims.height / 2 + i * 100,
            width: dims.width,
            height: dims.height,
            rotate: degrees(-35)
          })
        }
      }
    }
    // 序列化为字节
    const pdfBytes = await pdfDoc.save()
    this.preView(pdfBytes, docTitle)
  }

  // 合并文件
  async mergePdf2(urlList, fileName,isNeedDown=false) {
      let startTime = +new Date()
      // console.log(startTime)
      // eslint-disable-next-line
      let promises = [];
      urlList.map((url) => {
        // eslint-disable-next-line no-async-promise-executor
        let tmp = new Promise(async (resolve) => {
          const response = await axios({
            method: "get",
            url,
            responseType: "arraybuffer",
          });
          resolve(Buffer.from(response.data));
        });
        promises.push(tmp);
      });

      const pdfBuffers = await Promise.all(promises);

      const newPdf = await PDFDocument.create();
      for (let buffer of pdfBuffers) {
        const pdfDocument = await PDFDocument.load(buffer);
        const contentPages = await newPdf.copyPages(
          pdfDocument,
          pdfDocument.getPageIndices()
        );
        for (let page of contentPages) {
          newPdf.addPage(page);
        }
      }
      const uint8Array = await newPdf.save();
      let mergeBuffer = Buffer.from(uint8Array);

      var blob=new Blob([mergeBuffer]);

      if(isNeedDown){
        const url = window.URL.createObjectURL(blob);
        const link = document.createElement("a");
        link.href = url;
        link.setAttribute("download", fileName);
        if (typeof link.download === 'undefined') {
          link.setAttribute('target', '_blank')
        }
        // document.body.appendChild(link);
        // link.click();
        document.body.appendChild(link)
        link.click()
        document.body.removeChild(link)
      }else{
        const mergedPdfBlob = new Blob([mergeBuffer], {
          type: "application/pdf",
        });
        return URL.createObjectURL(mergedPdfBlob);;
      }
      // console.log(+new Date() - startTime)
  }

  async mergePdf3(pdfFileList, fileName,isNeedDown=false) {
    let pdfBuffers = [];
    pdfFileList.map((item) => {
      let dateArray=this.base64ToBuffer(item);
      pdfBuffers.push(Buffer.from(dateArray));
    });
    const newPdf = await PDFDocument.create();
    for (let buffer of pdfBuffers) {
      const pdfDocument = await PDFDocument.load(buffer);
      const contentPages = await newPdf.copyPages(
        pdfDocument,
        pdfDocument.getPageIndices()
      );
      for (let page of contentPages) {
        newPdf.addPage(page);
      }
    }
    const uint8Array = await newPdf.save();
    let mergeBuffer = Buffer.from(uint8Array);

    var blob=new Blob([mergeBuffer]);

    if(isNeedDown){
      const url = window.URL.createObjectURL(blob);
      const link = document.createElement("a");
      link.href = url;
      link.setAttribute("download", fileName);
      if (typeof link.download === 'undefined') {
        link.setAttribute('target', '_blank')
      }
      document.body.appendChild(link)
      link.click()
      document.body.removeChild(link)
    }else{
      const mergedPdfBlob = new Blob([mergeBuffer], {
        type: "application/pdf",
      });
      return URL.createObjectURL(mergedPdfBlob);;
    }
  }
  downloadBase64(base64Str,fileName) {
    let result = base64Str.replace(/[\r\n]/g, "");
    let pdfBase64 = `data:application/pdf;base64,${result}`;
    let url = URL.createObjectURL(this.base64ToBlob(pdfBase64));
    const link = document.createElement("a");
      link.href = url;
      link.setAttribute("download", fileName);
      if (typeof link.download === 'undefined') {
        link.setAttribute('target', '_blank')
      }
      document.body.appendChild(link)
      link.click()
      document.body.removeChild(link)

  }

  fileTobase64(file) {
    let reader = new FileReader();
    reader.readAsDataURL(file)
  }


  base64ToFile(base64Data, filename) { // 64转file
    if (typeof base64Data != 'string') {
      // this.$toast("urlData不是字符串")
      return;
    }
    var arr = base64Data.split(',')
    var type = arr[0].match(/:(.*?);/)[1]
    var fileExt = type.split('/')[1]
    var bstr = atob(arr[1])
    var n = bstr.length
    var u8arr = new Uint8Array(n)
    while (n--) {
      u8arr[n] = bstr.charCodeAt(n);
    }
    return new File([u8arr], filename +'.' + fileExt, {
      type: type
    });
  }

  base64ToBlob(base64Data) {
    let arr = base64Data.split(','),
    fileType = arr[0].match(/:(.*?);/)[1],
    bstr = atob(arr[1]),
    l = bstr.length,
    u8Arr = new Uint8Array(l);
    while (l--) {
        u8Arr[l] = bstr.charCodeAt(l);
    }
    return new Blob([u8Arr], {
        type: fileType
    });
  }

  base64ToBuffer(base64Str){
    const padding = '='.repeat((4 - base64Str.length % 4) % 4);
    const base64 = (base64Str + padding).replace(/\-/g, '+').replace(/_/g, '/');
    const rawData = window.atob(base64);
    const outputArray = new Uint8Array(rawData.length);
    for (let i = 0; i < rawData.length; ++i) {
        outputArray[i] = rawData.charCodeAt(i);
    }
    return outputArray;
  }


  // base64ToArrayBuffer(base64Str) {
  //   let arr = base64Data.split(','),
  //   fileType = arr[0].match(/:(.*?);/)[1],
  //   bstr = atob(result),
  //   l = bstr.length,
  //   u8Arr = new Uint8Array(l);
  //   while (l--) {
  //       u8Arr[l] = bstr.charCodeAt(l);
  //   }
  //   let blob = new Blob([u8Arr], {
  //     type: fileType
  //    });
  //   let reader = new FileReader();
  //   reader.onload = function(result) {
  //       console.log(result);
  //   }

  //   reader.readAsArrayBuffer(blob);
  // }

  base64File(base64Str,fileName){
    var fileExt=".pdf";

    var bstr = atob(base64Str)
    var n = bstr.length
    var u8arr = new Uint8Array(n)
    while (n--) {
      u8arr[n] = bstr.charCodeAt(n);
    }
    return new File([u8arr], fileName +'.' + fileExt, {
      type: type
    });
  }

  getObjectURL(file) {
    let url = null;
    if (window.createObjectURL != undefined) { // basic
        url = window.createObjectURL(file);
    } else if (window.webkitURL != undefined) { // webkit or chrome
        url = window.webkitURL.createObjectURL(file);
    } else if (window.URL != undefined) { // mozilla(firefox)
        url = window.URL.createObjectURL(file);
    }
    return url;
  }

  // 添加 canvas 水印
  addCanvasWatermark({ pdfDoc, text, docTitle }) {
    // 旋转角度大小
    const rotateAngle = Math.PI / 6;

    // labels是要显示的水印文字，垂直排列
    let labels = new Array();
    labels.push(text);

    const pages = pdfDoc.getPages()

    const size = pages[0].getSize()

    let pageWidth = size.width
    let pageHeight = size.height

    let canvas = document.createElement('canvas');
    let canvasWidth = canvas.width = pageWidth;
    let canvasHeight = canvas.height = pageHeight;

    const context = canvas.getContext('2d');
    context.font = "15px Arial";

    // 先平移到画布中心
    context.translate(pageWidth / 2, pageHeight / 2 - 250);
    // 在绕画布逆方向旋转30度
    context.rotate(-rotateAngle);
    // 在还原画布的坐标中心
    context.translate(-pageWidth / 2, -pageHeight / 2);

    // 获取文本的最大长度
    let textWidth = Math.max(...labels.map(item => context.measureText(item).width));

    let lineHeight = 15, fontHeight = 12, positionY, i
    i = 0, positionY = 0
    while (positionY <= pageHeight) {
      positionY = positionY + lineHeight * 5
      i++
    }
    canvasWidth += Math.sin(rotateAngle) * (positionY + i * fontHeight) // 给canvas加上画布向左偏移的最大距离
    canvasHeight = 2 * canvasHeight
    for (positionY = 0, i = 0; positionY <= canvasHeight; positionY = positionY + lineHeight * 5) {
      // 进行画布偏移是为了让画布旋转之后水印能够左对齐;
      context.translate(-(Math.sin(rotateAngle) * (positionY + i * fontHeight)), 0);
      for (let positionX = 0; positionX < canvasWidth; positionX += 2 * textWidth) {
        let spacing = 0;
        labels.forEach(item => {
          context.fillText(item, positionX, positionY + spacing);
          context.fillStyle = 'rgba(187, 187, 187, .8)'; // 字体颜色
          spacing = spacing + lineHeight;
        })
      }
      context.translate(Math.sin(rotateAngle) * (positionY + i * fontHeight), 0);
      context.restore();
      i++
    }
    // 图片的base64编码路径
    let dataUrl = canvas.toDataURL('image/png');
    // 使用Xhr请求获取图片Blob
    let xhr = new XMLHttpRequest();
    xhr.open("get", dataUrl, true);
    xhr.responseType = "blob";
    xhr.onload = res => {
      const imgBlob = res.target.response
      // 获取Blob图片Buffer
      imgBlob.arrayBuffer().then(async buffer => {
        const pngImage = await pdfDoc.embedPng(buffer)
        for(let i = 0; i < pages.length; i++) {
          pages[i].drawImage(pngImage)
        }
        // 序列化为字节
        const pdfBytes = await pdfDoc.save()
        this.preView(pdfBytes, docTitle)
      })
    }
    xhr.send();
  }

  // 预览
  preView(stream, docTitle) {
    const URL = window.URL || window.webkitURL;
    const href = URL.createObjectURL(new Blob([stream], { type: 'application/pdf;charset=utf-8' }))
    const wo = window.open(href)
    // 设置新打开的页签 document title
    let timer = setInterval(() => {
      if(wo.closed) {
        clearInterval(timer)
      } else {
        wo.document.title = docTitle
      }
    }, 500)
  }
}