html2canvas + JsPDF.js 导出pdf分页时的问题

问题描述

前一段时间 实现了html2canvas + jspdf.js 导出pdf的功能 项目当时没有测试做完就先搁置 最近项目要上线发现分页时问题 这篇文章记录一下之前的bug

import html2canvas from 'html2canvas';
import JsPDF from 'jspdf'
export function savePdf(el,  title) {
    html2canvas(el, {
      useCORS: true,
      allowTaint: true,
      dpi: 192,//导出pdf清晰度
      scale:2,
    })
    .then(async (canvas) => {
       // 新建JsPDF对象
       const pdf = new JsPDF("p", "mm", "a4");
       let ctx = canvas.getContext('2d'),
            a4w = 192, a4h = 277,    //A4大小，210mm x 297mm，四边各保留10mm的边距，显示区域190x277
            imgHeight = Math.floor(a4h * canvas.width / a4w),    //按A4显示比例换算一页图像的像素高度
            renderedHeight = 0;
            while(renderedHeight < canvas.height) {
                let page = document.createElement("canvas");
                page.width = canvas.width;
                page.height = Math.min(imgHeight, canvas.height - renderedHeight);//可能内容不足一页

                //用getImageData剪裁指定区域，并画到前面创建的canvas对象中
                page.getContext('2d').putImageData(ctx.getImageData(0, renderedHeight, canvas.width, Math.min(imgHeight, canvas.height - renderedHeight)), 0, 0);
                pdf.addImage(page.toDataURL('image/jpeg', 1.0), 'JPEG', 10, 10, a4w, Math.min(a4h, a4w * page.height / page.width));    //添加图像到页面，保留10mm边距

                renderedHeight += imgHeight;
                if(renderedHeight < canvas.height)
                    pdf.addPage();//如果后面还有内容，添加一个空页

                page = null
            }
            pdf.save(title + ".pdf");
    }).catch((e) => {
      console.log(e)
    }).finally(() => {});
}

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分页的pdf 就能正常的展示

参考地址: https://www.cnblogs.com/BoyTNT/p/11711439.html