Method cacheOneLayout

src/gridstack-engine.ts:1219–1231

* call to cache the given node layout internally to the given location so we can restore back when column changes size * @param node single node to cache * @param column corresponding column index to save it under

(n: GridStackNode, column: number)

   * @param column corresponding column index to save it under
   */
  public cacheOneLayout(n: GridStackNode, column: number): GridStackEngine {
    n._id = n._id ?? GridStackEngine._idSeq++;
    const l: GridStackNode = {x: n.x, y: n.y, w: n.w, _id: n._id}
    if (n.autoPosition || n.x === undefined) { delete l.x; delete l.y; if (n.autoPosition) l.autoPosition = true; }
    this._layouts = this._layouts || [];
    this._layouts[column] = this._layouts[column] || [];
    const index = this.findCacheLayout(n, column);
    if (index === -1)
      this._layouts[column].push(l);
    else
      this._layouts[column][index] = l;
    return this;
  }

  protected findCacheLayout(n: GridStackNode, column: number): number | undefined {
    return this._layouts?.[column]?.findIndex(l => l._id === n._id) ?? -1;