Source: MapData/TileMap.js

/**
 * Represents a Tile Map.
 */
class TileMap {
  constructor( data ) {
    /**
     * The name of the Tile Map
     */
    this.name = '';
    /**
     * The number of columns in the Tile Map
     */
    this.width = 0;
    /**
     * The number of rows in the Tile Map
     */
    this.height = 0;

    /**
     * Array of layer data
     */
    this.layers = [];

    if ( data ) {
      this.name = data.name;
      this.width = data.width;
      this.height = data.height;

      if ( data.layers ) {
        for ( let i = 0; i < data.layers.length; i += 1 ) {
          this.layers.push( this._getTypedArrayFromDataLayer( data.layers[i] ) );
        }
      }
    }
  }

  /**
   * Convert an array of numbers into a Uint16Array
   * @param {number[]} dataLayer
   */
  _getTypedArrayFromDataLayer( dataLayer ) {
    const result = new Uint16Array( this.width * this.height );
    for ( let i = 0; i < dataLayer.length; i += 1 ) {
      result[i] = dataLayer[i];
    }
    return result;
  }

  /**
   * Get the tile GID at a given position
   * @param {number} x - The x position
   * @param {number} y - The y position
   * @param {number} layer - The index of the layer on the tile map you are checking
   */
  getTile( x, y, layer = 0 ) {
    if ( layer < 0 || layer >= this.layers.length ) {
      return -1;
    }

    if ( x < 0 || x >= this.width ) {
      return -1;
    }

    if ( y < 0 || y >= this.height ) {
      return -1;
    }

    const currentLayer = this.layers[layer];
    const index = y * this.width + x;
    return currentLayer[index];
  }

  /**
   * Set the tile GID at a given position
   * @param {*} gid - The gid
   * @param {*} x - The x position
   * @param {*} y - The y position
   * @param {*} layer - The index of the layer on the tile map you are setting
   */
  setTile( gid, x, y, layer = 0 ) {
    if ( layer < 0 || layer >= this.layers.length ) {
      return;
    }

    if ( x < 0 || x >= this.width ) {
      return;
    }

    if ( y < 0 || y >= this.height ) {
      return;
    }

    const currentLayer = this.layers[layer];
    const index = y * this.width + x;
    currentLayer[index] = gid;
  }

  /**
   * get an array of the layer data, optionally only getting a subsection of the layer
   * @param {number} layer - The layer
   * @param {number} startX - The bottom left x position
   * @param {number} startY - The bottom left y position
   * @param {number} endX - The top right x position
   * @param {number} endY - The top right y position
   */
  getLayerData( layer = 0, startX = 0, startY = 0, endX = 0, endY = 0 ) {
    const finishX = endX || this.width;
    const finishY = endY || this.height;

    const width = finishX - startX;
    const height = finishY - startY;

    const data = new Array( width * height );

    for ( let y = 0; y < height; y += 1 ) {
      for ( let x = 0; x < width; x += 1 ) {
        const targetX = x + startX;
        const targetY = y + startY;

        if ( targetX < 0 || targetY < 0 || targetX >= this.width || targetY >= this.height ) {
          data[y * width + x] = 0;
          continue;
        }

        data[y * width + x] = this.getTile( targetX, targetY, layer );
      }
    }

    return { data, width, height };
  }
}

export default TileMap;