index.js

import { isNodePattern, throwError } from '@jimp/utils';

export default () => ({
  /**
   * Uniformly scales the image by a factor.
   * @param {number} f the factor to scale the image by
   * @param {string} mode (optional) a scaling method (e.g. Jimp.RESIZE_BEZIER)
   * @param {function(Error, Jimp)} cb (optional) a callback for when complete
   * @returns {Jimp} this for chaining of methods
   */
  scale(f, mode, cb) {
    if (typeof f !== 'number') {
      return throwError.call(this, 'f must be a number', cb);
    }

    if (f < 0) {
      return throwError.call(this, 'f must be a positive number', cb);
    }

    if (typeof mode === 'function' && typeof cb === 'undefined') {
      cb = mode;
      mode = null;
    }

    const w = this.bitmap.width * f;
    const h = this.bitmap.height * f;
    this.resize(w, h, mode);

    if (isNodePattern(cb)) {
      cb.call(this, null, this);
    }

    return this;
  },

  /**
   * Scale the image to the largest size that fits inside the rectangle that has the given width and height.
   * @param {number} w the width to resize the image to
   * @param {number} h the height to resize the image to
   * @param {string} mode (optional) a scaling method (e.g. Jimp.RESIZE_BEZIER)
   * @param {function(Error, Jimp)} cb (optional) a callback for when complete
   * @returns {Jimp} this for chaining of methods
   */
  scaleToFit(w, h, mode, cb) {
    if (typeof w !== 'number' || typeof h !== 'number') {
      return throwError.call(this, 'w and h must be numbers', cb);
    }

    if (typeof mode === 'function' && typeof cb === 'undefined') {
      cb = mode;
      mode = null;
    }

    const f =
      w / h > this.bitmap.width / this.bitmap.height
        ? h / this.bitmap.height
        : w / this.bitmap.width;
    this.scale(f, mode);

    if (isNodePattern(cb)) {
      cb.call(this, null, this);
    }

    return this;
  }
});