parcel-plugin-imagemin/lib/assets/ImageAsset.js

Parcel plugin to support image minification

const fs = require('fs');
const path = require('path');

const Asset = require('../parcelRequires').Asset;
const urlJoin = require('../urlJoin');

class ImageAsset extends Asset {
  constructor(...args) {
    super(...args);

    this.encoding = null;
  }

  async packageImage(options, location) {
    return imagemin([location]);
  }

  async transform() {
    if (this.options.minify) {
      let config = await this.getConfig(['imagemin.config.js'], {
        packageKey: 'imagemin'
      });

      let imagePath = path.resolve(this.name);
      let stat = await new Promise((resolve, reject) =>
        fs.stat(imagePath, (err, stats) => {
          if (err) return reject(err);
          resolve(stats);
        })
      );
      let originalFileSize = stat.size;
      let result = await this.packageImage(config, path.resolve(this.name));
      if (result[0] && result[0].data && Buffer.isBuffer(result[0].data)) {
        let minifiedSize = result[0].data.byteLength;
        // If compressed version is larger for some reason, skip it
        if (minifiedSize < originalFileSize) {
          this.outputData = result[0].data;
        }
      }
    }
  }

  generate() {
    // Don't return a URL to the JS bundle if there is a bundle loader defined for this asset type.
    // This will cause the actual asset to be automatically preloaded prior to the JS bundle running.
    if (this.options.bundleLoaders[this.type]) {
      return {};
    }

    const pathToAsset = urlJoin(this.options.publicURL, this.generateBundleName());

    return [
      {
        type: this.type,
        value: this.outputData || this.contents || null,
        hasDependencies: false
      }
    ];
  }
}

module.exports = ImageAsset;