class_docstr: Gather a set of glyphs relative to a given font name and size
  
  This currently stores characters in a `TextureAtlas` object which uses
  a 2D RGB texture to store unsigned 8-bit integer data. In the future this
  could be changed to a ``GL_R8`` texture instead of RGB when OpenGL ES
  3.0+ is standard. Since VisPy tries to stay compatible with OpenGL ES 2.0
  we are using an ``RGB`` texture. Using a single channel texture should
  improve performance by requiring less data to be sent to the GPU and to
  remote backends (jupyter notebook).
  
  Parameters
  ----------
  font : dict
      Dict with entries "face", "size", "bold", "italic".
  renderer : instance of SDFRenderer
      SDF renderer to use.
class_docstr_tok: ["Gather","a","set","of","glyphs","relative","to","a","given","font","name","and","size","This","currently","stores","characters","in","a","`","TextureAtlas","`","object","which","uses","a","2D","RGB","texture","to","store","unsigned","8-bit","integer","data",".","In","the","future","this","could","be","changed","to","a","``","GL_R8","``","texture","instead","of","RGB","when","OpenGL","ES","3.0+","is","standard",".","Since","VisPy","tries","to","stay","compatible","with","OpenGL","ES","2.0","we","are","using","an","``","RGB","``","texture",".","Using","a","single","channel","texture","should","improve","performance","by","requiring","less","data","to","be","sent","to","the","GPU","and","to","remote","backends","(","jupyter","notebook",")",".","Parameters","--","--","--","--","--","font",":","dict","Dict","with","entries","``","face","''",",","``","size","''",",","``","bold","''",",","``","italic","''",".","renderer",":","instance","of","SDFRenderer","SDF","renderer","to","use","."]
code: def __getitem__(self, char):
      if not (isinstance(char, str) and len(char) == 1):
          raise TypeError("index must be a 1-character string")
      if char not in self._glyphs:
          self._load_char(char)
      return self._glyphs[char]
  
imports: from __future__ import division
  import numpy
  from copy import deepcopy
  import sys
  from ._sdf_gpu import SDFRendererGPU
  from ._sdf_cpu import _calc_distance_field
  from ...gloo import TextureAtlas, IndexBuffer, VertexBuffer
  from ...gloo import context
  from ...gloo.wrappers import _check_valid
  from ...util.fonts import _load_glyph
  from ..transforms import STTransform
  from ...color import ColorArray
  from ..visual import Visual
  from ...io import load_spatial_filters
label_desc: Use image node_id 4 for calling the TextureFont obj's underlying member method code with example usage: obj.__getitem__(char) and returns: self