getReadOptions(source, options) {
    if (options) {
      let dataProjection = options.dataProjection
        ? getProjection(options.dataProjection)
        : this.readProjection(source);
      if (
        options.extent &&
        dataProjection &&
        dataProjection.getUnits() === 'tile-pixels'
      ) {
        dataProjection = getProjection(dataProjection);
        dataProjection.setWorldExtent(options.extent);
      }
      options = {
        dataProjection: dataProjection,
        featureProjection: options.featureProjection,
      };
    }
    return this.adaptOptions(options);
  }
Adds the data projection to the read options.
@param {Document|Element|Object|string} source Source.
@param {ReadOptions} [options] Options.
@return {ReadOptions|undefined} Options.
@protected