Image in PDF cut off: How to make a canvas fit entirely in a PDF page?

问题

When placing the canvas in the PDF using the jspdf library makes the image cut off.

html2canvas(myContainer, {background: 'red'}).then (canvas) ->
  imgData = canvas.toDataURL('image/jpeg', 1.0)
  window.open(imgData) # this is just a test that opens the image in a new tab and it displays nicely, the entire image
  pdf = new jsPDF("l", "pt", "b1") # tried a variety of formats but no luck
  pdf.addImage(imgData, 'JPEG', 0, 0)
  pdf.save('file.pdf') # the generated pdf that contains the image gets trimmed

Does anyone have any ideas how to make the canvas fit?

回答1:

Try setting the width and height of the image as well (in any case, there is little documentation for addImage it seems):

var pdf = new jsPDF("l", "mm", "a4");
var imgData = canvas.toDataURL('image/jpeg', 1.0);

// due to lack of documentation; try setting w/h based on unit
pdf.addImage(imgData, 'JPEG', 10, 10, 180, 150);  // 180x150 mm @ (10,10)mm

回答2:

I have a solution for you :

function saveImageToPdf(idOfHtmlElement)
{
   var fbcanvas = document.getElementById(idOfHtmlElement);
   html2canvas($(fbcanvas),
        {

            onrendered: function (canvas) {

                var width = canvas.width;
                var height = canvas.height;
                var millimeters = {};
                millimeters.width = Math.floor(width * 0.264583);
                millimeters.height = Math.floor(height * 0.264583);

                var imgData = canvas.toDataURL(
                    'image/png');
                var doc = new jsPDF("p", "mm", "a4");
                doc.deletePage(1);
                doc.addPage(millimeters.width, millimeters.height);
                doc.addImage(imgData, 'PNG', 0, 0);
                doc.save('WebSiteScreen.pdf');
            }
        });
}

The things you have to do is:

Convert pixels to mm.
Delete first not resized properly page
Create a new one with good size in mm.
Save image.

回答3:

Here's the solution that worked for me, for my use case:

var canvas = document.getElementById('canvas');
var imgData = canvas.toDataURL("image/png");
var pdf = new jsPDF('p', 'pt', [canvas.width, canvas.height]);
var pdfWidth = pdf.internal.pageSize.getWidth();
var pdfHeight = pdf.internal.pageSize.getHeight();
pdf.addImage(imgData, 'PNG', 0, 0, pdfWidth, pdfHeight);
pdf.save("mypdf.pdf");

回答4:

It looks like the size of the image and page size of the pdf is not the same. you can either set the page size ie. add a page with defined height and width similar to the image or you can set options for the image while adding it into the pdf.

Example for method 1 : Answered above
Example for method 2:

    var pdf = new jsPDF("l", "mm", "a4");   //orientation: landscape
    var imgData = canvas.toDataURL('image/png');
    var width = pdf.internal.pageSize.getWidth();
    var height = pdf.internal.pageSize.getHeight();
    pdf.addImage(imgData, 'PNG', 0, 0, width, height); 
    pdf.save('download.pdf');

来源：https://stackoverflow.com/questions/29578721/image-in-pdf-cut-off-how-to-make-a-canvas-fit-entirely-in-a-pdf-page

标签

canvas

html2canvas

jspdf