class_docstr: Convert strings to dvi files using TeX, caching the results to a directory.
docstr: Generate a png file containing latex's rendering of tex string.
  
  Return the file name.
code: def make_png(self, tex, fontsize, dpi):
      """
      Generate a png file containing latex's rendering of tex string.
  
      Return the file name.
      """
      basefile = self.get_basefile(tex, fontsize, dpi)
      pngfile = "%s.png" % basefile
      # see get_rgba for a discussion of the background
      if not os.path.exists(pngfile):
          dvifile = self.make_dvi(tex, fontsize)
          self._run_checked_subprocess(
              [
                  "dvipng",
                  "-bg",
                  "Transparent",
                  "-D",
                  str(dpi),
                  "-T",
                  "tight",
                  "-o",
                  pngfile,
                  dvifile,
              ],
              tex,
          )
      return pngfile
  
imports: from __future__ import absolute_import, division, print_function
  import six
  import copy
  import glob
  import os
  import shutil
  import sys
  import warnings
  import logging
  from hashlib import md5
  import distutils.version
  import numpy
  import matplotlib
  from matplotlib import rcParams
  from matplotlib._png import read_png
  from matplotlib.cbook import mkdirs, Locked
  from matplotlib.compat.subprocess import subprocess, Popen, PIPE, STDOUT
  import matplotlib.dviread
  import re
label_desc: Use image node_id 11 for calling the TexManager obj's underlying member method code with example usage: obj.make_png(tex, fontsize, dpi) and returns: pngfile