如何使用 jspdf 和 html2canvas 打印全屏

Question

您好，我在我的应用程序中使用 Angular8。在这里，我使用 jspdf 和 html2canvas 将 html 转换为 pdf。但我只能打印半页而不是整页。任何人都可以帮助我哪里出错了。

我附上了一个演示，当我 select 下拉列表中的任何值时，都会打开另一个 div，所以我需要获取 div 中所有内容的完整值部分。请帮忙。我得到这样的输出，但它不包含预期的完整值：

如果有任何其他方法可以输出我的要求也被接受。

TS:

 public downloadPdf() {
    var data = document.getElementById('pdfDownload');
    html2canvas(data).then(canvas => {
      // Few necessary setting options
      var imgWidth = 208;
      var imgHeight = canvas.height * imgWidth / canvas.width;
      alert(imgHeight)
      const contentDataURL = canvas.toDataURL('image/png')
      let pdf = new jspdf('p', 'mm', 'a4'); // A4 size page of PDF
      var position = 0;
      pdf.addImage(contentDataURL, 'PNG', 0, position, imgWidth, imgHeight);
      //  pdf.save('new-file.pdf');
      window.open(pdf.output('bloburl', { filename: 'new-file.pdf' }), '_blank');
    });
 
  }

Answer 1

为此，您必须在 html2canvas 方法 scrollY 中添加选项 {scrollY: -window.scrollY} 它将获取完全渲染页面的屏幕截图。

html2canvas(数据, {scrollY: -window.scrollY, 比例: 1}

除此之外，我们知道滚动条中有数据。为此，您必须暂时删除 scroll 并需要在 pdf 生成后添加。你可以通过简单地添加 id 来做到这一点 <ul class="list-group list-group-flush vert-scrollable-150" id="alldata"> 元素。

// 为禁用滚动编码

document.getElementById('alldata').style.overflow = 'inherit'; document.getElementById('alldata').style.maxHeight = 'inherit';

      async downloadPdf() {
    var data = document.getElementById('pdfDownload');
    $('pdfOpenHide').attr('hidden', true);
    // disable the scroll
     document.getElementById('alldata').style.overflow = 'inherit';
     document.getElementById('alldata').style.maxHeight = 'inherit';

   await  html2canvas(data, {scrollY: -window.scrollY, 
   scale: 1}).then(canvas => {
      // Few necessary setting options
      var imgWidth = 150;
      var imgHeight = canvas.height * imgWidth / canvas.width;
      const contentDataURL = canvas.toDataURL('image/png', 1.0)
// enabling the scroll 
      document.getElementById('alldata').style.overflow = 'scroll';
        document.getElementById('alldata').style.maxHeight = '150px';

      let pdf = new jspdf('l', 'mm','a4'); // A4 size page of PDF
      var position = 0;
   // add tghis width height according to your requirement
      const divHeight = data.clientHeight
  const divWidth = data.clientWidth
  const ratio = divHeight / divWidth;

       const width = pdf.internal.pageSize.getWidth();
    let height = pdf.internal.pageSize.getHeight();
        height = ratio * width;
      pdf.addImage(contentDataURL, 'PNG', 0, position, width, height);
      window.open(pdf.output('bloburl', { filename: 'new-file.pdf' }), '_blank');
    }); 
}

如果滚动条中的数据较多，您也可以使用jspdf添加一个页面。

更多参考，你可以查看这个 HTML2Canvas does not render full div, only what is visible on screen?

另一个解决方案：如果数据更多

   async downloadPdf() {
        var data = document.getElementById("pdfDownload");
        $("pdfOpenHide").attr("hidden", true);
        // To disable the scroll
        document.getElementById("alldata").style.overflow = "inherit";
        document.getElementById("alldata").style.maxHeight = "inherit";
    
        await html2canvas(data, { scrollY: -window.scrollY, scale: 1 }).then(
          canvas => {
            const contentDataURL = canvas.toDataURL("image/png", 1.0);
            // enabling the scroll
            document.getElementById("alldata").style.overflow = "scroll";
            document.getElementById("alldata").style.maxHeight = "150px";
    
            let pdf = new jspdf("l", "mm", "a4"); // A4 size page of PDF
    
            let imgWidth = 300;
            let pageHeight = pdf.internal.pageSize.height;
            let imgHeight = (canvas.height * imgWidth) / canvas.width;
            let heightLeft = imgHeight;
            let position = 0;
    
            pdf.addImage(contentDataURL, "PNG", 0, position, imgWidth, imgHeight);
            heightLeft -= pageHeight;
    
            while (heightLeft >= 0) {
              position = heightLeft - imgHeight;
              pdf.addPage();
              pdf.addImage(contentDataURL, "PNG", 0, position, imgWidth, imgHeight);
              heightLeft -= pageHeight;
            }
            window.open(
              pdf.output("bloburl", { filename: "new-file.pdf" }),
              "_blank"
            );
          }
        );
      }

Answer 2

不是从图像创建 pdf，而是使用 jspdf 的 addHtml 方法直接从 html 创建 pdf。这已解决您的问题。我创建了以下代码使用它。

您必须在索引页的页眉部分添加此脚本

<script src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/0.4.1/html2canvas.js"></script>

public downloadPdf() {
$("pdfOpenHide").attr("hidden", true);
var removeClass = document.getElementsByClassName("vert-scrollable-150");
removeClass[0].classList.add("RemoveThisClass");
removeClass[0].classList.remove("vert-scrollable-150");

var data = document.getElementById("pdfDownload");
const pdf = new jspdf("p", "pt", "a4");
pdf.addHTML(data, () => {
  window.open(
    pdf.output("bloburl", { filename: "new-file.pdf" }),
    "_blank"
  );
});
var addClass = document.getElementsByClassName("RemoveThisClass");
addClass[0].classList.add("vert-scrollable-150");
addClass[0].classList.remove("RemoveThisClass"); 

}

它会为你工作。你也可以参考

Answer 3

试试这个：

public downloadPdf() {
    var data = document.getElementById('pdfDownload');
    html2canvas(data, { useCORS:true}) // useCORS is optional if your images are externally hosted somewhere like s3
    .then(canvas => {
      const contentDataURL = canvas.toDataURL('image/png')
      let pdf = new jspdf('p', 'pt', [canvas.width, canvas.height]);
      var pdfWidth = pdf.internal.pageSize.getWidth();
      var pdfHeight = pdf.internal.pageSize.getHeight();
      pdf.addImage(contentDataURL, 'PNG', 0, pdfWidth, pdfHeight);
      //  pdf.save('new-file.pdf');
      window.open(pdf.output('bloburl', { filename: 'new-file.pdf' }), '_blank');
    });
 
  }

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