def _item_box_size(self, context, horiz, idx):
    'Calculates the amount of space needed for drawing an\n        individual vertex at the bottom of the dendrogram.'
    if ((self._names is None) or (self._names[idx] is None)):
        (x_bearing, _, _, height, x_advance, _) = context.text_extents('')
    else:
        (x_bearing, _, _, height, x_advance, _) = context.text_extents(str(self._names[idx]))
    if horiz:
        return ((x_advance - x_bearing), height)
    return (height, (x_advance - x_bearing))
Calculates the amount of space needed for drawing an
individual vertex at the bottom of the dendrogram.
def _item_box_size(self, context, horiz, idx):
    'Calculates the amount of space needed for drawing an\n        individual vertex at the bottom of the dendrogram.'
    if ((self._names is None) or (self._names[idx] is None)):
        (x_bearing, _, _, height, x_advance, _) = context.text_extents()
    else:
        (x_bearing, _, _, height, x_advance, _) = context.text_extents(str(self._names[idx]))
    if horiz:
        return ((x_advance - x_bearing), height)
    return (height, (x_advance - x_bearing))