Method getUnitLayoutInfo

src/coord/matrix/MatrixDim.ts:416–420

* Get leaf cell or get level info. * Should be able to return null/undefined if not found on x or y, thus input `dimIdx` is needed.

(dimIdx: number, locator: MatrixXYLocator)

     * Should be able to return null/undefined if not found on x or y, thus input `dimIdx` is needed.
     */
    getUnitLayoutInfo(dimIdx: number, locator: MatrixXYLocator): MatrixCellLayoutInfo | NullUndefined {
        return dimIdx === this.dimIdx
            ? (locator < this._leavesCount ? this._cells[locator] : undefined)
            : this._levels[locator + this._levels.length];
    }

    /**
     * Get dimension cell by data, including leaves and non-leaves.