psy_web_share/utils/pdf.js

// 创建 pdf.js
// 引入依赖
import Vue from 'vue'
import html2canvas from 'html2canvas'
// #ifdef H5 
import JsPDF from 'jspdf'
// #endif
const PDF = {}
PDF.install = function (Vue, options) {
  /**
   * targetDom: 需要打印的dom对象
   * name:pdf的名字
   * callback: 回调函数
   */
  Vue.prototype.$createPdf = function (targetDom, name, callback) {
    // console.log(window.devicePixelRatio * 4)
    // a4纸的尺寸[592.28,841.89]
    uni.showLoading({
      title: '导出中'
    })
    const A4_WIDTH = 592.28
    const A4_HEIGHT = 841.89 
    // 每页pdf 相对于A4纸张的页面所对应的高度
    let pageHeight = targetDom.scrollWidth / A4_WIDTH * A4_HEIGHT
    //将dom对象复制一份出来，我们要对dom对象的大小进行调整，不能影响原页面dom对象的样式
    let cloneDom = targetDom.cloneNode(true)
    cloneDom.style.width = targetDom.scrollWidth + 'px'
    cloneDom.style.background = '#FFFFFF'
    // cloneDom.style.display = 'none'
    document.body.appendChild(cloneDom)
    //这里划重点，将页面中的预计生成一页的div设置一个单独的class，然后根据class获取到所有的节点，即可大致知道将要生成多少页的PDF
    let pages = cloneDom.childNodes
    //遍历一次这些节点
    for (let i = 0; i < pages.length; i++) {
      //判断每个页面的节点对象，高度是否大于或小于实际的PDF的高度，如果大于PDF每页的高度，那这个节点最少也要生成2页的PDF，切不能影响下面的节点的，用节点对象的高度/PDF每页的高度，向上取整获取到倍数，然后设置该节点的高度为：PDF每页的高度*倍数，如果节点高度小于PDF每页的高度，直接将该节点高度设置成PDF每页的高度即可
      if (pages[i].offsetHeight > pageHeight) {
        let num = Math.ceil(pages[i].offsetHeight / pageHeight)
        pages[i].style.height = pageHeight * num + 'px'
      } else {
        // pages[i].style.height = pageHeight + 'px'
      }
	  
      //页面中每页的div之间有间隔，将这个间隔去掉
      // pages[i].style.marginBottom = 0 + 'px'
    }
	 
    html2canvas(cloneDom, {
      scale: 4, // 提升画面质量，但是会增加文件大小
      useCORS: true, // 允许跨域图片 当图片是链接地址时，需加该属性，否组无法显示图片
      imageTimeout: 0, // 图片加载延迟，默认延迟为0，单位毫秒
      height: cloneDom.scrollHeight, // canvas的高度设定，这里的宽高要用复制出来的dom对象的宽高，不能用原dom对象，因为我们已经将dom的高度整体拉高了
      width: cloneDom.scrollWidth, // canvas的宽度设定
      windowWidth: document.body.scrollWidth,
      windowHeight: document.body.scrollHeight,
      dpi: 172, // 将分辨率提高到特定的DPI
      logging: false,
      allowTaint: false,
    }).then(canvas => {
      document.body.removeChild(cloneDom) // 移除节点否者会多出一份
      const _this = this;
      //未生成pdf的html页面高度
      var leftHeight = canvas.height;
      var a4Width = 555.28 // 原A4宽 592 因为要设置边距 20 ,这里要减掉 40
      var a4Height = 801.89 // 原A4高   841 因为要设置边距 20 ,这里要减掉 40
      //一页pdf显示html页面生成的canvas高度;
      var a4HeightRef = Math.floor(canvas.width / a4Width * a4Height);
 
      //pdf页面偏移
      var position = 0;
 
      var pageData = canvas.toDataURL('image/jpeg', 1.0);
 
      var pdf = new JsPDF('x', 'pt', 'a4');
      var index = 1,
        canvas1 = document.createElement('canvas'),
        height;
      pdf.setDisplayMode('fullwidth', 'continuous', 'FullScreen');
 
      function createImpl(canvas) {
        if (leftHeight > 0) {
          index++;
          var checkCount = 0;
          if (leftHeight > a4HeightRef) {
            var i = position + a4HeightRef;
            for (i = position + a4HeightRef; i >= position; i--) {
              var isWrite = true
              for (var j = 0; j < canvas.width; j++) {
                var c = canvas.getContext('2d').getImageData(j, i, 1, 1).data
 
                if (c[0] != 0xff || c[1] != 0xff || c[2] != 0xff) {
                  isWrite = false
                  break
                }
              }
              if (isWrite) {
                checkCount++
                if (checkCount >= 10) {
                  break
                }
              } else {
                checkCount = 0
              }
            }
            height = Math.round(i - position) || Math.min(leftHeight, a4HeightRef);
            if (height <= 0) {
              height = a4HeightRef;
            }
          } else {
            height = leftHeight;
          }
 
          canvas1.width = canvas.width;
          canvas1.height = height;
 
          // console.log(index, 'height:', height, 'pos', position);
 
          var ctx = canvas1.getContext('2d');
          ctx.drawImage(canvas, 0, position, canvas.width, height, 0, 0, canvas.width, height); // 边距这里设置0，不然又黑边
 
          var pageHeight = Math.round(a4Width / canvas.width * height);
          // pdf.setPageSize(null, pageHeight)
          if (position != 0) {
            pdf.addPage();
          }
          // 设置 20px 边距
          pdf.addImage(canvas1.toDataURL('image/jpeg', 1.0), 'JPEG', 20, 20, a4Width, a4Width / canvas1.width * height);
          leftHeight -= height;
          position += height;
          // $('.pdfProgress').text(index + 1);
          // $('.pdfTotal').text(index + Math.ceil(leftHeight / a4HeightRef));
          if (leftHeight > 0) {
            //添加全屏水印
            const base64 = 'data:image/png;base64,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'
            for (let i = 0; i < 6; i++) {
              for (let j = 0; j < 5; j++) {
                const left = (j * 120) + 20;
                // pdf.addImage(base64,'JPEG', left, i*150, 20, 30); // 关掉水印
              }
            }
            setTimeout(createImpl, 500, canvas);
          } else {
            pdf.save(name + '.pdf');
            uni.hideLoading()
          }
        }
      }
 
      //当内容未超过pdf一页显示的范围，无需分页
      if (leftHeight < a4HeightRef) {
        pdf.addImage(pageData, 'JPEG', 20, 20, a4Width, a4Width / canvas.width * leftHeight);
        pdf.save('下载pdf文件名' + '.pdf')
        uni.hideLoading()
      } else {
        try {
          pdf.deletePage(0);
          setTimeout(createImpl, 500, canvas);
 
        } catch (err) {
          console.log(err);
        }
      }
    })
  }
}
Vue.use(PDF)
export default PDF