docs: @Pure
  	public int getColumnFor(double x) {
  		final double xx = x - this.bounds.getMinX();
  		if (xx >= 0.)  {
  			final int idx = (int) (xx / getCellWidth());
  			assert idx >= 0;
  			if (idx < getColumnCount()) {
  				return idx;
  			}
  			return getColumnCount() - 1;
  		}
  		return 0;
  	}