image-size-stream.js

'use strict';

var Transform = require('stream').Transform;
var imageSize = require('image-size');

const LIMIT = 128 * 1024;

class ImageSizeStream extends Transform {
  constructor () {
    super();
    this._buffer = new Buffer([]);
  }
  
  _transform (chunk, enc, cb) {
    this._enc = enc;
    this._buffer = Buffer.concat([this._buffer, chunk]);

    if (!this._dimensions) {
      try {
        this._dimensions = imageSize(this._buffer);
      } catch (e) {
        this._detectionError = e;
        if (this._buffer.length > LIMIT) {
          this.emit('error', this._detectionError);
        }
      }
      if (this._dimensions) {
        this.emit('size', this._dimensions);
      }
    }

    this.push(chunk);
    cb();
  }
  
  _flush (cb) {
    console.log(7);
    if (!this._dimensions) {
      this.emit('error', this._detectionError);
      cb();
      return;
    }
  }
}

module.exports = function createImageSizeStream() {
  return new ImageSizeStream();
};