class_docstr: Convert strings to dvi files using TeX, caching the results to a directory.
  
  The cache directory is called ``tex.cache`` and is located in the directory
  returned by `.get_cachedir`.
  
  Repeated calls to this constructor always return the same instance.
class_docstr_tok: ["Convert","strings","to","dvi","files","using","TeX",",","caching","the","results","to","a","directory",".","The","cache","directory","is","called","``","tex.cache","``","and","is","located","in","the","directory","returned","by","`",".get_cachedir","`",".","Repeated","calls","to","this","constructor","always","return","the","same","instance","."]
docstr: Generate a png file containing latex's rendering of tex string.
  
  Return the file name.
docstr_tok: ["Generate","a","png","file","containing","latex","'s","rendering","of","tex","string",".","Return","the","file","name","."]
code: def make_png(cls, tex, fontsize, dpi):
      """
      Generate a png file containing latex's rendering of tex string.
  
      Return the file name.
      """
      basefile = cls.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 = cls.make_dvi(tex, fontsize)
          cmd = [
              "dvipng",
              "-bg",
              "Transparent",
              "-D",
              str(dpi),
              "-T",
              "tight",
              "-o",
              pngfile,
              dvifile,
          ]
          # When testing, disable FreeType rendering for reproducibility; but
          # dvipng 1.16 has a bug (fixed in f3ff241) that breaks --freetype0
          # mode, so for it we keep FreeType enabled; the image will be
          # slightly off.
          if (
              getattr(mpl, "_called_from_pytest", False)
              and mpl._get_executable_info("dvipng").raw_version
              != "1.16"
          ):
              cmd.insert(1, "--freetype0")
          cls._run_checked_subprocess(cmd, tex)
      return pngfile
  
imports: import functools
  import hashlib
  import logging
  import os
  from pathlib import Path
  import subprocess
  from tempfile import TemporaryDirectory
  import numpy
  import matplotlib
  from matplotlib import _api, cbook, dviread
label_desc: Use image node_id 11 for calling the TexManager obj's underlying member method code with example usage: obj.make_png(cls, tex, fontsize, dpi) and returns: pngfile