index.js

const express = require("express");
const sharp = require("sharp");
const config = require("./config.json");
const port = config.port;
const rposition = ['left top', 'top', 'right top', 'left', 'center', 'right', 'left bottom', 'bottom', 'right bottom']; //Order based on GflAX object for compatiblity reasons
const fit = ['cover', 'contain', 'fill', 'inside', 'outside'];

const app = express();
app.disable("x-powered-by");

//Disable file/memory caching
sharp.cache(false);

app.get("/", function (req, res) {
  res.send("Sharp Image Processing System");
});

app.get("/generate", async (req, res) => {
  try {
    let source = req.query.source;
    let dest = req.query.dest;
    let width = req.query.width == "0" ? null : parseInt(req.query.width);
    let height = req.query.height == "0" ? null : parseInt(req.query.height);
    let fileExt = dest.split(".").pop().toLowerCase();
    let sourceFileExt = source.split(".").pop().toLowerCase();
    let quality = parseInt(req.query.quality) || 80;
    let lossless = strToBool(req.query.lossless) ? true : false;
    let progressive = strToBool(req.query.progressive) ? true : false;
    let wimage = req.query.wimage || "";
    let wposition = req.query.wposition || "southeast";
	let imgFit = (req.query.fit!='')?parseInt(req.query.fit) : 0;

    const image = sharp(source);

    await image.withMetadata().rotate();
    if (sourceFileExt != "jpg" && sourceFileExt != "jpeg" && fileExt == "jpg")
      await image.flatten({ background: "#ffffff" });

    if (width != null || height != null) await image.resize({width, height, fit:fit[imgFit], background:{r:255,g:255,b:255,alpha:0} });
    if (wimage != "") {
      await image.composite([{ input: wimage, gravity: wposition }]);
    }
    switch (fileExt) {
      case "png":
        await image.png({ quality: quality, progressive: progressive });
        break;
      case "jpg":
        await image.jpeg({ quality: quality, progressive: progressive });
        break;
      case "webp":
        await image.webp({ quality: quality, lossless: lossless });
        break;
    }

    await image.toFile(dest);
    res.send(dest);
    // console.log(source + " -> " + dest);
  } catch (e) {
    res.send(e.message);
    // console.error(e);
  }
});

app.get("/getinfo", async (req, res) => {
  try {
    let source = req.query.source;
    const image = sharp(source);
    const metadata = await image.metadata();
    res.send(metadata);
  } catch (e) {
    res.send(e);
  }
});

app.get("/getsize", async (req, res) => {
  try {
    let source = req.query.source;
    const image = sharp(source);
    const metadata = await image.metadata();
    res.send(`${metadata.width}x${metadata.height}`);
  } catch (e) {
    res.send(e);
  }
});

app.listen(port, console.log.bind(console, "Listening on port " + port));

function strToBool(s) {
  // will match one and only one of the string 'true','1', or 'on' regardless
  // of capitalization and regardless off surrounding white-space.
  let regex = /^\s*(true|1|on)\s*$/i;
  return regex.test(s);
}