Jimp: Promise based write/getBuffer

[Vanuan]

Currently, write needs callback.
I'd like to be able to do this:

image.getBuffer(Jimp.MIME_JPEG).then(function(buffer) {
  res.writeHead(200, {
     'Content-Type': Jimp.MIME_JPEG,
     'Content-Length': buffer.length
   });
   res.end(buffer);
})

[gabrielalan]

+1

[oliver-moran]

It's a little bit awkward because methods, write and getBuffer, are currently designed for chaining, like this:

image.scale(0.5).write("image-small.jpg").greyscale()..write("image-small-greyscale.jpg");

[efernandesng]

@oliver-moran node-horseman has a good chaining strategy. It use bluebird as Promise implementation.

You can continue using callbacks through the bluebird .asCallback.

[oliver-moran]

@efernandesng, thanks and apologies for delay getting back. I'll look into this for the release after next.

[ryuken]

Any progress on this?

[thisconnect]

I'd love native Promises for all jimp methods. Bluebird should not be included by default, it could be used opt-in. Chaning the API requires the test https://github.com/oliver-moran/jimp/issues/227 to be implemented first

[AshwinMekala]

Any progress on this?

[majiy]

As a workaround for the time being, using Bluebird promisify:

const bluebird = require('bluebird');
const jimp = require('jimp');
jimp.prototype.getBufferAsync = bluebird.promisify( jimp.prototype.getBuffer );

[ilyaLibin]

Node 8, has built in promisify method

const util = require('util');
const jimp = require('jimp');
jimp.prototype.getBufferAsync = util.promisify( jimp.prototype.getBuffer );

[SourceBoy]

For >= ES6, native Promise is available:

(new Promise((resolve, reject) => {
  <img>.getBuffer(<mime>, (error, buf) => {
    return error ? reject(error) : resolve(buf);
  });
})).then((buf) => {
  // Do something with buf
}).catch((error) => {
  // error from getBuffer()
});

[FireController1847]

Using promisify now results in a "cannot read property 'width' of undefined". Any status on making this a promise?

[webarthur]

+1

[septs]

@FireController1847

import { promisify } from "util";

const jimp = new Jimp(100, 100); // jimp object
const boundGetBuffer = promisify(jimp.getBuffer.bind(jimp));

async function main() {
   const buffer = await boundGetBuffer();
}
main();

see https://mdn.io/bind
see https://nodejs.org/dist/latest/docs/api/util.html#util_util_promisify_original

[FireController1847]

I had actually been doing it wrong and got it to work lol, thanks anyways