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# -*- coding: utf-8 -*-
"""Tools for handling LaTeX.
Authors:
* Brian Granger
"""
#-----------------------------------------------------------------------------
# Copyright (c) 2010, IPython Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file COPYING.txt, distributed with this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from StringIO import StringIO
from base64 import encodestring
#-----------------------------------------------------------------------------
# Tools
#-----------------------------------------------------------------------------
def latex_to_png(s, encode=False):
"""Render a LaTeX string to PNG using matplotlib.mathtext.
Parameters
----------
s : str
The raw string containing valid inline LaTeX.
encode : bool, optional
Should the PNG data bebase64 encoded to make it JSON'able.
"""
from matplotlib import mathtext
mt = mathtext.MathTextParser('bitmap')
f = StringIO()
mt.to_png(f, s, fontsize=12)
bin_data = f.getvalue()
if encode:
bin_data = encodestring(bin_data)
return bin_data
_data_uri_template_png = """<img src="data:image/png;base64,%s" alt=%s />"""
def latex_to_html(s, alt='image'):
"""Render LaTeX to HTML with embedded PNG data using data URIs.
Parameters
----------
s : str
The raw string containing valid inline LateX.
alt : str
The alt text to use for the HTML.
"""
base64_data = latex_to_png(s, encode=True)
return _data_uri_template_png % (base64_data, alt)
# From matplotlib, thanks to mdboom. Once this is in matplotlib releases, we
# will remove.
def math_to_image(s, filename_or_obj, prop=None, dpi=None, format=None):
"""
Given a math expression, renders it in a closely-clipped bounding
box to an image file.
*s*
A math expression. The math portion should be enclosed in
dollar signs.
*filename_or_obj*
A filepath or writable file-like object to write the image data
to.
*prop*
If provided, a FontProperties() object describing the size and
style of the text.
*dpi*
Override the output dpi, otherwise use the default associated
with the output format.
*format*
The output format, eg. 'svg', 'pdf', 'ps' or 'png'. If not
provided, will be deduced from the filename.
"""
from matplotlib import figure
# backend_agg supports all of the core output formats
from matplotlib.backends import backend_agg
from matplotlib.font_manager import FontProperties
from matplotlib.mathtext import MathTextParser
if prop is None:
prop = FontProperties()
parser = MathTextParser('path')
width, height, depth, _, _ = parser.parse(s, dpi=72, prop=prop)
fig = figure.Figure(figsize=(width / 72.0, height / 72.0))
fig.text(0, depth/height, s, fontproperties=prop)
backend_agg.FigureCanvasAgg(fig)
fig.savefig(filename_or_obj, dpi=dpi, format=format)
return depth
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