How to center continued text using PdfKit? - node.js

Question

I have this code:
const PDFDocument = require("pdfkit");
const QRCode = require("qrcode");
const fs = require("fs");
const exec = async () => {
const doc = new PDFDocument({ layout: "landscape" });
doc.pipe(fs.createWriteStream("output.pdf"));
for (let pageNumber = 1; pageNumber <= 1000; pageNumber++) {
const url = await QRCode.toDataURL("I am a url!");
doc
.image(url, 10, 100, {
width: 420,
height: 420,
align: "center",
valign: "center",
})
doc
.font("Helvetica")
.fontSize(50)
.fillColor("#000")
.text(`Item `, 465, 200, { continued: true })
.fontSize(55)
.font("Courier-Bold")
.fillColor("#1b83c5")
.text(`${pageNumber}`);
doc
.font("Helvetica-Bold")
.fontSize(40)
.fillColor("#000")
.text("Order and Pay", 420, 320);
doc.addPage();
}
doc.end();
};
exec();
Which would produce something like this:
It looks centered and all, but as pages increase it will no longer be centered since the numbers are fixed.
I saw in the docs that there's an align property, but the docs didn't explain how to handle continued text.
Any working examples?

Answer 1

Maybe it's a little late, but I found a solution battling with the same problem:
First you need to create a constant with the width of the container you want to center your text in: (this value you have to calculate or invent, but it's easy to do that)
const containerWidth = 100 // as an example
Then, you need to create a variable that contains a plain string that contains all the text you want to center, in your example:
var appendedText = `Item ${pageNumber}`
To finish, you need to use pdf-kit's function: widthOfString, and add the text in the document as follows:
const xOffset = 465 // The original X offset value
doc
.text(`Item `, xOffset + (containerWidth / 2) - (doc.widthOfString(appendedText) / 2), 200, { continued: true })
.text(`${pageNumber}`);
Removed the text styling lines for clarity, but you have to add them later.