Javascript jsPDF addHTML将低质量图像导出为PDF_Javascript_Pdf_Jspdf

Javascript jsPDF addHTML将低质量图像导出为PDF

javascript pdf

Javascript jsPDF addHTML将低质量图像导出为PDF,javascript,pdf,jspdf,Javascript,Pdf,Jspdf,过去2天的简单问题搜索，但未找到解决方案我正在使用jsPDF的addHTML api将html转换为pdf $('#loadPdf').on('click', function() { var pdf = new jsPDF('p', 'in', 'a4'); pdf.addHTML($('#complete')[0], function() { pdf.save('new.pdf'); pdf.output('d

过去2天的简单问题搜索，但未找到解决方案我正在使用jsPDF的addHTML api将html转换为pdf

$('#loadPdf').on('click', function() {
        var pdf = new jsPDF('p', 'in', 'a4');
        pdf.addHTML($('#complete')[0], function() {
            pdf.save('new.pdf');
            pdf.output('datauri');
        });
    });

这是产生模糊图像的pdf文本显示模糊。我搜索了很多，找到了一些链接（在下面分享），但没有得到答案

是否有任何方法可以获得高质量的图像pdf。若我并没有使用AddHTMLAPI和任何其他api，那个么图像不会以pdf格式显示。帮助请查看此解决方案：

发件人：


某品牌




伪造页面内容
酷导出测试页面！
Lorem ipsum dolor sit amet，是一位杰出的献身者。刚从老鼠身上取下的元素。根据康努比亚·诺斯特拉（conubia nostra）和希梅纳奥斯（inceptos himenaeos）的规定，社会责任和责任等级为：。这是一辆汽车。在《老街日报》中，康莫多·普莱克托斯（commodo Placelat lectus）。Sed ac ullamcorper直径。库拉比图尔是利奥。非口述马萨。对价和对价

出口1
出口2

又一个头球！
Lorem ipsum dolor sit amet，是一位杰出的献身者。刚从老鼠身上取下的元素
小组标题
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好的，这可能是足够的数据了
最后用一些lorem ipsum来结束
这是一个页脚

这很好用

          var ctx = onePageCanvas.getContext('2d');
          //set the image quality
            ctx.webkitImageSmoothingEnabled = true;
            ctx.mozImageSmoothingEnabled = true;
            ctx.imageSmoothingEnabled = true;
            ctx.imageSmoothingQuality = "high";

            ctx.drawImage(srcImg,0,0); //this gives good img quality 

            var canvasDataURL = onePageCanvas.toDataURL("image/png", 1.0); //set png image with quality

            var width         = onePageCanvas.width;
            var height        = onePageCanvas.height;

           pdf.addImage(canvasDataURL, 'PNG', 10, 10, (width*.62), (height*.62),undefined,'FAST'); //addimage to jspdf

我从这次讨论中找到了答案：并以这种方式实施，适用于我的用例：

    var A4_width = 595; //pixels
    var A4_height = 842; //pixels
    var ratio = 2; // scale for higher image's dpi

    var oldCanvas = document.createElement('canvas');
    oldCanvas.width = A4_width;
    oldCanvas.height = A4_height;
    var oldContext = oldCanvas.getContext('2d');
    var oldImg = new Image();
    oldImg.src = oldCanvas.toDataURL();
    oldContext.drawImage(oldImg, 0, 0, A4_width, A4_height);

    var newImg = new Image();
    newImg.onload = function () {
        var newCanvas = document.createElement('canvas');
        newCanvas.width = A4_width * ratio;
        newCanvas.height = A4_height * ratio;
        var newContext = newCanvas.getContext('2d');

        // Scale and draw the source image to the canvas
        newContext.drawImage(newImg, 0, 0, A4_width * ratio, A4_height * ratio);
        newImg.src = newCanvas.toDataURL();
        var pdfDoc = new jsPDF({
            unit: 'mm'
        });
        pdfDoc.addImage(newImg, 'png', 0, 0, 210, 297); // imageData, format, x, y, w, h
        pdfDoc.save('testFile.pdf'); //save file
        newImg.onload = undefined; // kill the func
    }
    newImg.src = oldImg.src; //set source to the old image

这个问题与缩放有关。在我的例子中，在角度应用程序中，我在运行时将高度和宽度增加了一倍。这解决了我的问题。你也可以尝试增加身高和体重。它将解决这个问题

import * as jsPDF from 'jspdf';
import * as html2canvas from "html2canvas";
import * as $ from 'jquery';
export class Print {
    static exportTwo(elem: any,progress:any) {
        var canvasToImage = function (canvas: any) {
            var img = new Image();
            var dataURL = canvas.toDataURL('image/png', 0.92);
            img.src = dataURL;
            return img;
        };
        var canvasShiftImage = function (oldCanvas: any, shiftAmt: any) {
            shiftAmt = parseInt(shiftAmt) || 0;
            if (!shiftAmt) { return oldCanvas; }

            var newCanvas = document.createElement('canvas');
            newCanvas.height = oldCanvas.height - shiftAmt;
            newCanvas.width = oldCanvas.width;
            var ctx = newCanvas.getContext('2d');
            ctx['imageSmoothingEnabled'] = false; /* standard */
            ctx['mozImageSmoothingEnabled'] = false; // Firefox 
            ctx['oImageSmoothingEnabled'] = false; // Opera /
            ctx['webkitImageSmoothingEnabled'] = false; // Safari /
            ctx['msImageSmoothingEnabled'] = false; // IE */
            //ctx.fillStyle = "#";
            var img = canvasToImage(oldCanvas);
            ctx.drawImage(img, 0, shiftAmt, img.width, img.height, 0, 0, img.width, img.height);

            return newCanvas;
        };


        var canvasToImageSuccess = function (canvas: any) {
            var l = {
                orientation: 'p',
                unit: 'mm',
                format: 'a4',
                compress: true,
                fontSize: 40,
                lineHeight: 1,
                autoSize: false,
                printHeaders: true
            };
            var pdf = new jsPDF(l),
                pdfInternals = pdf.internal,
                pdfPageSize = pdfInternals.pageSize,
                pdfScaleFactor = pdfInternals.scaleFactor,
                pdfPageWidth = pdfPageSize.width,
                pdfPageHeight = pdfPageSize.height,
                totalPdfHeight = 0,
                htmlPageHeight = canvas.height,
                htmlScaleFactor = canvas.width / (pdfPageWidth * pdfScaleFactor),
                safetyNet = 0;
            while (totalPdfHeight < htmlPageHeight && safetyNet < 15) {
                var newCanvas = canvasShiftImage(canvas, totalPdfHeight);
                pdf.addImage(newCanvas, 'PNG', 0, 0, pdfPageWidth, pdfPageHeight, 'NONE', 'SLOW');

                totalPdfHeight += (pdfPageHeight * pdfScaleFactor * htmlScaleFactor);

                if (totalPdfHeight < (htmlPageHeight)) {
                    pdf.addPage();
                }
                safetyNet++;
            }
            var source = $('#print')[0];
            pdf.save('invoice.pdf');
        };

        var bigCanvas = $("<div>").appendTo($('#print'));  // This will be the 2x sized canvas we're going to render
        var scaledElement = $('#print').clone()
            .css({
                'margin': '2%',
                'padding': '1%',
                'transform': 'scale(2,2)',
                'transform-origin': '0 0',
            })
            .appendTo(bigCanvas);

        var oldWidth = scaledElement.width();
        var oldHeight = scaledElement.height();

        var newWidth = oldWidth * 2;
        var newHeight = oldHeight * 2;

        bigCanvas.css({
            'width': newWidth+200,
            'height': newHeight+200,
            'margin': '2%',
            'padding': '1%',
        })

        html2canvas(bigCanvas[0]).then((canvas: any) => {
            canvasToImageSuccess(canvas);
            bigCanvas.remove();
            progress.done();
        });
    }
}

从“jsPDF”导入*为jsPDF；
从“html2canvas”导入*作为html2canvas；
从“jquery”导入*为$；
导出类打印{
静态导出2（元素：任意，进度：任意）{
var canvasToImage=函数（画布：任意）{
var img=新图像（）；
var dataURL=canvas.toDataURL（'image/png'，0.92）；
img.src=数据URL；
返回img；
};
瓦坎瓦
import * as jsPDF from 'jspdf';
import * as html2canvas from "html2canvas";
import * as $ from 'jquery';
export class Print {
    static exportTwo(elem: any,progress:any) {
        var canvasToImage = function (canvas: any) {
            var img = new Image();
            var dataURL = canvas.toDataURL('image/png', 0.92);
            img.src = dataURL;
            return img;
        };
        var canvasShiftImage = function (oldCanvas: any, shiftAmt: any) {
            shiftAmt = parseInt(shiftAmt) || 0;
            if (!shiftAmt) { return oldCanvas; }

            var newCanvas = document.createElement('canvas');
            newCanvas.height = oldCanvas.height - shiftAmt;
            newCanvas.width = oldCanvas.width;
            var ctx = newCanvas.getContext('2d');
            ctx['imageSmoothingEnabled'] = false; /* standard */
            ctx['mozImageSmoothingEnabled'] = false; // Firefox 
            ctx['oImageSmoothingEnabled'] = false; // Opera /
            ctx['webkitImageSmoothingEnabled'] = false; // Safari /
            ctx['msImageSmoothingEnabled'] = false; // IE */
            //ctx.fillStyle = "#";
            var img = canvasToImage(oldCanvas);
            ctx.drawImage(img, 0, shiftAmt, img.width, img.height, 0, 0, img.width, img.height);

            return newCanvas;
        };


        var canvasToImageSuccess = function (canvas: any) {
            var l = {
                orientation: 'p',
                unit: 'mm',
                format: 'a4',
                compress: true,
                fontSize: 40,
                lineHeight: 1,
                autoSize: false,
                printHeaders: true
            };
            var pdf = new jsPDF(l),
                pdfInternals = pdf.internal,
                pdfPageSize = pdfInternals.pageSize,
                pdfScaleFactor = pdfInternals.scaleFactor,
                pdfPageWidth = pdfPageSize.width,
                pdfPageHeight = pdfPageSize.height,
                totalPdfHeight = 0,
                htmlPageHeight = canvas.height,
                htmlScaleFactor = canvas.width / (pdfPageWidth * pdfScaleFactor),
                safetyNet = 0;
            while (totalPdfHeight < htmlPageHeight && safetyNet < 15) {
                var newCanvas = canvasShiftImage(canvas, totalPdfHeight);
                pdf.addImage(newCanvas, 'PNG', 0, 0, pdfPageWidth, pdfPageHeight, 'NONE', 'SLOW');

                totalPdfHeight += (pdfPageHeight * pdfScaleFactor * htmlScaleFactor);

                if (totalPdfHeight < (htmlPageHeight)) {
                    pdf.addPage();
                }
                safetyNet++;
            }
            var source = $('#print')[0];
            pdf.save('invoice.pdf');
        };

        var bigCanvas = $("<div>").appendTo($('#print'));  // This will be the 2x sized canvas we're going to render
        var scaledElement = $('#print').clone()
            .css({
                'margin': '2%',
                'padding': '1%',
                'transform': 'scale(2,2)',
                'transform-origin': '0 0',
            })
            .appendTo(bigCanvas);

        var oldWidth = scaledElement.width();
        var oldHeight = scaledElement.height();

        var newWidth = oldWidth * 2;
        var newHeight = oldHeight * 2;

        bigCanvas.css({
            'width': newWidth+200,
            'height': newHeight+200,
            'margin': '2%',
            'padding': '1%',
        })

        html2canvas(bigCanvas[0]).then((canvas: any) => {
            canvasToImageSuccess(canvas);
            bigCanvas.remove();
            progress.done();
        });
    }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.5.3/jspdf.debug.js" 
        integrity="sha384-NaWTHo/8YCBYJ59830LTz/P4aQZK1sS0SneOgAvhsIl3zBu8r9RevNg5lHCHAuQ/"
        crossorigin="anonymous">
</script>
<script src="https://html2canvas.hertzen.com/dist/html2canvas.min.js"></script>
<script>
    function download() {
        let pdf = new jsPDF('l', 'pt', 'a4');
        pdf.html(document.getElementById('id'), {
            callback: function () {
                //pdf.save('test.pdf');
                window.open(pdf.output('bloburl')); // to debug
            }
        });
    }
</script>

function createPDFObject() {
  html2canvas(document.getElementById("main"), {
   onrendered:function(canvas) {

  var contentWidth = canvas.width;
  var contentHeight = canvas.height;

  //One page pdf shows the height of canvas generated by html page;
  var pageHeight = contentWidth / 592.28 * 841.89;
  //html page height without pdf generation
  var leftHeight = contentHeight;
  //Page offset
  var position = 0;
  //a4 paper size [595.28841.89], width and height of image in pdf of canvas generated by html page
  var imgWidth = 595.28; 
  var imgHeight = 592.28/contentWidth * contentHeight;

  //Return picture dataURL, parameters: picture format and sharpness (0-1)
  var pageData = canvas.toDataURL('image/jpeg', 1.0);

  //Direction is vertical by default, dimension ponits, format A4 [595.28841.89]
  var pdf = new jsPDF('', 'pt', 'a4');

  //There are two heights to distinguish, one is the actual height of the html page, and the height of the generated pdf page (841.89)
  //When the content does not exceed the display range of one page of pdf, paging is not required
  if (leftHeight < pageHeight) {
      pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight );
  } else {
      while(leftHeight > 0) {
          pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
          leftHeight -= pageHeight;
          position -= 841.89;
          //Avoid adding blank pages
          if(leftHeight > 0) {
            pdf.addPage();
          }
      }
  }
  pdf.save('stone.pdf');