How to use the pureimage.encodePNGToStream function in pureimage

console.log('Rendering vector field...')
  var scene = PImage.make(width, height);

  var ctx = scene.getContext('2d');
  var imgData = ctx.getImageData();

  for (var x = 0; x < width; ++x) {
    for (var y = 0; y < height; ++y) {
      var encodedVelocity = encodeVelocity(velocities[x][y]);
      imgData.setPixelRGBA_i(x, y, encodedVelocity.r, encodedVelocity.g, encodedVelocity.b, encodedVelocity.a);
    }
  }

  // Texture is ready. Dump it onto the file system:
  var textureName = OUT_IMAGE_NAME + '.png';
  PImage.encodePNGToStream(scene, fs.createWriteStream(textureName)).then(()=> {
      console.log('wrote out the png file to ' + textureName);
      if (saveOriginalLayout) {
        // This is just for debugging purposes.
        return saveGraphLayoutIntoImage(rect, layout);
      }
  }).catch(e => {
      console.log('there was an error writing', e);
  });
}

if (t.length == 2) { // 2
        ctx.fillText(t, (size / 2) - (fontSize / 2), size / 1.4);
    } else if (t.length == 1) { // 1
        ctx.fillText(t, size / 2 - (fontSize / 4), size / 1.4);
    } else { // 0
        ctx.fillText(t, 0, 0);
    }

    let writeStream;
    if (typeof outputFilePathOrStream === 'string') {
      writeStream = fs.createWriteStream(outputFilePathOrStream);
    } else {
      writeStream = outputFilePathOrStream;
    }

    PImage.encodePNGToStream(img, writeStream).then(() => {
      winston.debug(`wrote out the png file to ${outputFilePathOrStream}`);
      callback(outputFilePathOrStream)
    }).catch((e) => {
      winston.error("there was an error writing", e);
      callback(outputFilePathOrStream)
    });
  });
}

function saveGraphLayoutIntoImage(rect, layout) {
  var width = rect.x2 - rect.x1;
  var height = rect.y2 - rect.y1;
  var scene = PImage.make(width, height);
  var ctx = scene.getContext('2d');

  clearRectangle(ctx, width, height);
  ctx.fillStyle = 'rgba(0, 200, 230, 1)';
  layout.forEachBody(body => {
    ctx.fillRect(body.pos.x - rect.x1 - 5, body.pos.y - rect.y1 - 5, 10, 10);
  });

  saveVoronoiIfNeeded(ctx, layout, rect);

  var fileName = OUT_IMAGE_NAME + '.layout.png';
  PImage.encodePNGToStream(scene, fs.createWriteStream(fileName)).then(()=> {
      console.log('wrote out the png file to ' + fileName);
  }).catch(e => {
    console.log('failed to save layout image', e);
  });
}

return await new Promise((resolve, reject) => {
        const stream = new PassThrough();
        const data: number[] = [];

        stream
            .on("data", (chunk: typeof data) => data.push(...chunk))
            .on("error", (error) => reject(error))
            .on("end", () => {
                encodingPromise
                    .then(() => resolve(Buffer.from(data)))
                    .catch(reject);
            });

        const encodingPromise = encodePNGToStream(source, stream);
    });
}

return new Promise((resolve, reject) => {
            let data = [];
            const converter = new stream.Writable({
                write: function (chunk, encoding, next) {
                    data.push(chunk);
                    next();
                }
            });

            converter.on('finish', () => {
                resolve(Buffer.concat(data));
            });

            converter.on('error', error => reject(error));

            PImage.encodePNGToStream(pImage, converter);
        }).then(buffer => {
            return nativeImage.createFromBuffer(buffer, {