def chart_measure(self, bars):
        """
        Measure the width of each table column.
        """
        width = 0
        for bar in bars:
            # Calculate maximum from:
            width = max(
                width,                      # current label max width
                len(bar.get('label', '')),  # column label width
                bar.get('width_min', 0),    # configured column minimal width
            )
        return width