JSPDF - addHTML() Multiple Canvas Page

问题

I noticed already have a release "addHTML() can now split the canvas into multiple pages" which can find through this link : https://github.com/MrRio/jsPDF/releases/tag/v1.0.138.

May i know how it work? In my case, i just tried it out when click on "save as pdf" button, it just render a single page instead of multiple pages (sometimes didn't worked, i assume because the content is too long to be generated as pdf).

Would appreciate if there are some examples for this case. Thanks!

Attached my codes below:

var pdf = new jsPDF('p', 'pt', 'a4');

pdf.addHTML($(".pdf-wrapper"), function () {
    var string = pdf.output('datauristring');
    pdf.save("test.pdf");
});

回答1:

Splitting canvas into multiple pages work by providing a "pagesplit" option:

var pdf = new jsPDF('p', 'pt', 'a4');
var options = {
         pagesplit: true
    };

pdf.addHTML($(".pdf-wrapper"), options, function()
{
    pdf.save("test.pdf");
});

回答2:

pdf.addHtml doesnot work if there are svg images on the web page.. I copy the solution here: // suppose your picture is already in a canvas var imgData = canvas.toDataURL('image/png'); /* Here are the numbers (paper width and height) that I found to work. It still creates a little overlap part between the pages, but good enough for me. if you can find an official number from jsPDF, use them. */

var imgWidth = 210; 
var pageHeight = 295;  
var imgHeight = canvas.height * imgWidth / canvas.width;
var heightLeft = imgHeight;

var doc = new jsPDF('p', 'mm');
var position = 0;

doc.addImage(imgData, 'PNG', 0, position, imgWidth, imgHeight);
heightLeft -= pageHeight;

while (heightLeft >= 0) {
  position = heightLeft - imgHeight;
  doc.addPage();
  doc.addImage(imgData, 'PNG', 0, position, imgWidth, imgHeight);
  heightLeft -= pageHeight;
}
doc.save( 'file.pdf');

回答3:

None of the above helped me so I'll put this here for anyone who arrives at this page looking to use addHTML() to create a single pdf split into multiple pages with a different html element on each page. I used recursion so I'm not sure of the performance implications of this approach. It worked for me to create a 4 page pdf from 4 div elements.

var pdf = new jsPDF('landscape');
        var pdfName = 'test.pdf';

        var options = {};

        var $divs = $('.myDivClass')                //jQuery object of all the myDivClass divs
        var numRecursionsNeeded = $divs.length -1;     //the number of times we need to call addHtml (once per div)
        var currentRecursion=0;

        //Found a trick for using addHtml more than once per pdf. Call addHtml in the callback function of addHtml recursively.
        function recursiveAddHtmlAndSave(currentRecursion, totalRecursions){
            //Once we have done all the divs save the pdf
            if(currentRecursion==totalRecursions){
                pdf.save(pdfName);
            }else{
                currentRecursion++;
                pdf.addPage();
                //$('.myDivClass')[currentRecursion] selects one of the divs out of the jquery collection as a html element
                //addHtml requires an html element. Not a string like fromHtml.
                pdf.addHTML($('.myDivClass')[currentRecursion], 15, 20, options, function(){
                    console.log(currentRecursion);
                    recursiveAddHtmlAndSave(currentRecursion, totalRecursions)
                });
            }
        }

        pdf.addHTML($('.myDivClass')[currentRecursion], 15, 20, options, function(){
            recursiveAddHtmlAndSave(currentRecursion, numRecursionsNeeded);
        });
}

回答4:

With using pagesplit: true it always stretches the pdf output. Try to use an old version of jsPDF with html2canvas of course.

Sharing the result of my 2 days trial to achieve the multipage PDF generation with addHTML not fromHTML since it looses the CSS rules.

<script src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/0.4.1/html2canvas.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.0.272/jspdf.debug.js"></script>

then the PDF should be just fine as follows:

<script>

            $(window).on('load', function(){

                var pdf = new jsPDF('p', 'pt', 'a4');

                var pdfName = 'sample.pdf';

                var options = {
                    format: 'JPEG',
//                    pagesplit: true,
                    "background": '#000',
                };

                var fullPage = $('#Printout_21571')[0],
                    firstPartPage = $('#part-1')[0],
                    secondPartPage = $('#part-2')[0];

                pdf.addHTML(firstPartPage, 15, 20, options, function(){ pdf.addPage() });
                pdf.addHTML(secondPartPage, 15, 20, options, function(){});

                setTimeout(function() {

//                    pdf.save(pdfName);
                    var blob = pdf.output("blob");
                    window.open(URL.createObjectURL(blob));

                }, 600);
            })
        </script>

Hope this would help. Thanks!

来源：https://stackoverflow.com/questions/25904440/jspdf-addhtml-multiple-canvas-page

标签

javascript

jquery

canvas

html2canvas

jspdf