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