index.js

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

import Resize from './modules/resize';
import Resize2 from './modules/resize2';

export default () => ({
  constants: {
    RESIZE_NEAREST_NEIGHBOR: 'nearestNeighbor',
    RESIZE_BILINEAR: 'bilinearInterpolation',
    RESIZE_BICUBIC: 'bicubicInterpolation',
    RESIZE_HERMITE: 'hermiteInterpolation',
    RESIZE_BEZIER: 'bezierInterpolation'
  },

  class: {
    /**
     * Resizes the image to a set width and height using a 2-pass bilinear algorithm
     * @param {number} w the width to resize the image to (or Jimp.AUTO)
     * @param {number} h the height to resize the image to (or Jimp.AUTO)
     * @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
     */
    resize(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;
      }

      if (w === this.constructor.AUTO && h === this.constructor.AUTO) {
        return throwError.call(this, 'w and h cannot both be set to auto', cb);
      }

      if (w === this.constructor.AUTO) {
        w = this.bitmap.width * (h / this.bitmap.height);
      }

      if (h === this.constructor.AUTO) {
        h = this.bitmap.height * (w / this.bitmap.width);
      }

      if (w < 0 || h < 0) {
        return throwError.call(this, 'w and h must be positive numbers', cb);
      }

      // round inputs
      w = Math.round(w);
      h = Math.round(h);

      if (typeof Resize2[mode] === 'function') {
        const dst = {
          data: Buffer.alloc(w * h * 4),
          width: w,
          height: h
        };
        Resize2[mode](this.bitmap, dst);
        this.bitmap = dst;
      } else {
        const image = this;
        const resize = new Resize(
          this.bitmap.width,
          this.bitmap.height,
          w,
          h,
          true,
          true,
          buffer => {
            image.bitmap.data = Buffer.from(buffer);
            image.bitmap.width = w;
            image.bitmap.height = h;
          }
        );
        resize.resize(this.bitmap.data);
      }

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

      return this;
    }
  }
});