It's easy to fit the page if you only have one image. The more challenge task is to fit images with various sizes to a pdf file. The key to archive that is to calculate the aspect ratio of the image and relative width/height ratio of the page. The following code is what I used to convert multiple images online to a PDF file. It will rotate the image(s) based on the orientation of the images/page and set proper margin. My project use images with online src. You should be able to modify to suit your needs.
As for image rotation, if you see a blank page after rotation, it could simply be that the image is out of bounds. See this answer for details.
function exportPdf(urls) {
let pdf = new jsPDF('l', 'mm', 'a4');
const pageWidth = pdf.internal.pageSize.getWidth();
const pageHeight = pdf.internal.pageSize.getHeight();
const pageRatio = pageWidth / pageHeight;
for (let i = 0; i < urls.length; i++) {
let img = new Image();
img.src = urls[i];
img.onload = function () {
const imgWidth = this.width;
const imgHeight = this.height;
const imgRatio = imgWidth / imgHeight;
if (i > 0) { pdf.addPage(); }
pdf.setPage(i + 1);
if (imgRatio >= 1) {
const wc = imgWidth / pageWidth;
if (imgRatio >= pageRatio) {
pdf.addImage(img, 'JPEG', 0, (pageHeight - imgHeight / wc) / 2, pageWidth, imgHeight / wc, null, 'NONE');
}
else {
const pi = pageRatio / imgRatio;
pdf.addImage(img, 'JPEG', (pageWidth - pageWidth / pi) / 2, 0, pageWidth / pi, (imgHeight / pi) / wc, null, 'NONE');
}
}
else {
const wc = imgWidth / pageHeight;
if (1 / imgRatio > pageRatio) {
const ip = (1 / imgRatio) / pageRatio;
const margin = (pageHeight - ((imgHeight / ip) / wc)) / 4;
pdf.addImage(img, 'JPEG', (pageWidth - (imgHeight / ip) / wc) / 2, -(((imgHeight / ip) / wc) + margin), pageHeight / ip, (imgHeight / ip) / wc, null, 'NONE', -90);
}
else {
pdf.addImage(img, 'JPEG', (pageWidth - imgHeight / wc) / 2, -(imgHeight / wc), pageHeight, imgHeight / wc, null, 'NONE', -90);
}
}
if (i == urls.length - 1) {
pdf.save('Photo.pdf');
}
}
}
}
If this is a bit hard to follow, you can also use
.addPage([imgWidth, imgHeight])
, which is more straightforward. The downside of this method is that the first page is fixed bynew jsPDF()
. See this answer for details.