copitpastit/router/qrcode.js

const CONFIG = require('../src/config.js');
const PasteContent = require('../models/pasteContent.js').PasteContent;
const QRCode = require("qrcode");
const { createCanvas, loadImage } = require("canvas");

async function createQrCode(url, params) {
    const width = params?.width || 500;
    const canvas = createCanvas(width, width);

    QRCode.toCanvas(
        canvas,
        url,
        {
            width: width,
            errorCorrectionLevel: "H",
            margin: 1,
            color: {
                dark: params?.dark || "#333",
                light: params?.light || "#eee"
            },
    });

    if (params?.centerImage) {
        const ctx = canvas.getContext("2d");
        const img = await loadImage(params.centerImage);
        const sizeFactor = (width/3.5)/Math.max(img.width, img.height);
        ctx.drawImage(img, 0, 0, img.width, img.height, (width - img.width*sizeFactor) /2, (width - img.height*sizeFactor) /2, img.width * sizeFactor, img.height * sizeFactor);
    }
    return canvas.toBuffer();
}

module.exports = {
    register: app => {
        // Params:
        //  - s: size (in px)
        //  - bg: bg color
        //  - fg: fg color
        //  - origin: to append to the url
        app.router.get("/:id/qrcode.png", async (req, res) => {
            if (!req.body.origin)
                return app.routerUtils.onPageNotFound(res);
            let entity = await app.databaseHelper.findOne(PasteContent, { publicId: req.params.id });
            if (!entity)
                return app.routerUtils.onPageNotFound(res);
            const qrcode = await createQrCode(decodeURIComponent(req.body.origin) +"/x/" +entity.publicId +(req.body.rel ? ("?rel="+decodeURIComponent(req.body.rel)) : ""), {
                width: req.body.s ? Number.parseInt(req.body.s) : undefined,
                light: req.body.bg ? decodeURIComponent(req.body.bg) : undefined,
                dark: req.body.fg ? decodeURIComponent(req.body.fg) : undefined,
            });
            res.writeHead(200, { "Content-Type": "image/png", "Content-Length": qrcode.length, "Cache-Control": "max-age=604800" }); // Cache=1 week
            res.end(qrcode);
        });
    }
};