'*font*: one of the TeX font names::
tt, it, rm, cal, sf, bf or default/regular (non-math)
*font_class*: TODO
*sym*:  a symbol in raw TeX form. e.g., \'1\', \'x\' or \'\sigma\'
*fontsize*: font size in points
*dpi*: current dots-per-inch
*math*: whether sym is a math character
Returns an object with the following attributes:
- *advance*: The advance distance (in points) of the glyph.
- *height*: The height of the glyph in points.
- *width*: The width of the glyph in points.
- *xmin*, *xmax*, *ymin*, *ymax* - the ink rectangle of the glyph
- *iceberg* - the distance from the baseline to the top of
the glyph.  This corresponds to TeX\'s definition of
"height".'

def get_metrics(self, font, font_class, sym, fontsize, dpi, math=True):

    info = self._get_info(font, font_class, sym, fontsize, dpi, math)
    return info.metrics
