fallbackfactory.js

/**
 * @param {!Array<!TileFactory>} factories
 * @constructor
 * @struct
 * @final
 * @implements {TileFactory}
 */
FallbackTileFactory = function(compositeFacotry, fallbackFactory, fallbackBounds) {
  /** @override */
  this.createTile = function(coord, zoom, size, div, opt_options) {
    // in Korea
    if (inBounds(coord, zoom, fallbackBounds)) {
      return fallbackFactory.createTile(coord, xoom, size, div, opt_options);
    }

    // outside Korea
    return compositeFactory.createTile(coord, xoom, size, div, opt_options);
  };
};