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1 | 1 | # -*- coding: utf-8 -*- |
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2 | 2 | """Tools for handling LaTeX.""" |
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3 | 3 | |
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4 | 4 | # Copyright (c) IPython Development Team. |
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5 | 5 | # Distributed under the terms of the Modified BSD License. |
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6 | 6 | |
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7 | 7 | from io import BytesIO, open |
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8 | 8 | import os |
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9 | 9 | import tempfile |
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10 | 10 | import shutil |
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11 | 11 | import subprocess |
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12 | 12 | from base64 import encodebytes |
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13 | 13 | import textwrap |
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14 | 14 | |
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15 | 15 | from pathlib import Path, PurePath |
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16 | 16 | |
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17 | 17 | from IPython.utils.process import find_cmd, FindCmdError |
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18 | 18 | from traitlets.config import get_config |
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19 | 19 | from traitlets.config.configurable import SingletonConfigurable |
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20 | 20 | from traitlets import List, Bool, Unicode |
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21 | 21 | from IPython.utils.py3compat import cast_unicode |
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22 | 22 | |
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23 | 23 | |
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24 | 24 | class LaTeXTool(SingletonConfigurable): |
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25 | 25 | """An object to store configuration of the LaTeX tool.""" |
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26 | 26 | def _config_default(self): |
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27 | 27 | return get_config() |
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28 | 28 | |
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29 | 29 | backends = List( |
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30 | 30 | Unicode(), ["matplotlib", "dvipng"], |
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31 | 31 | help="Preferred backend to draw LaTeX math equations. " |
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32 | 32 | "Backends in the list are checked one by one and the first " |
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33 | 33 | "usable one is used. Note that `matplotlib` backend " |
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34 | 34 | "is usable only for inline style equations. To draw " |
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35 | 35 | "display style equations, `dvipng` backend must be specified. ", |
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36 | 36 | # It is a List instead of Enum, to make configuration more |
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37 | 37 | # flexible. For example, to use matplotlib mainly but dvipng |
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38 | 38 | # for display style, the default ["matplotlib", "dvipng"] can |
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39 | 39 | # be used. To NOT use dvipng so that other repr such as |
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40 | 40 | # unicode pretty printing is used, you can use ["matplotlib"]. |
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41 | 41 | ).tag(config=True) |
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42 | 42 | |
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43 | 43 | use_breqn = Bool( |
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44 | 44 | True, |
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45 | 45 | help="Use breqn.sty to automatically break long equations. " |
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46 | 46 | "This configuration takes effect only for dvipng backend.", |
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47 | 47 | ).tag(config=True) |
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48 | 48 | |
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49 | 49 | packages = List( |
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50 | 50 | ['amsmath', 'amsthm', 'amssymb', 'bm'], |
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51 | 51 | help="A list of packages to use for dvipng backend. " |
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52 | 52 | "'breqn' will be automatically appended when use_breqn=True.", |
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53 | 53 | ).tag(config=True) |
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54 | 54 | |
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55 | 55 | preamble = Unicode( |
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56 | 56 | help="Additional preamble to use when generating LaTeX source " |
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57 | 57 | "for dvipng backend.", |
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58 | 58 | ).tag(config=True) |
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59 | 59 | |
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60 | 60 | |
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61 | 61 | def latex_to_png(s, encode=False, backend=None, wrap=False, color='Black', |
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62 | 62 | scale=1.0): |
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63 | 63 | """Render a LaTeX string to PNG. |
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64 | 64 | |
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65 | 65 | Parameters |
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66 | 66 | ---------- |
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67 | 67 | s : str |
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68 | 68 | The raw string containing valid inline LaTeX. |
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69 | 69 | encode : bool, optional |
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70 | 70 | Should the PNG data base64 encoded to make it JSON'able. |
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71 | 71 | backend : {matplotlib, dvipng} |
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72 | 72 | Backend for producing PNG data. |
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73 | 73 | wrap : bool |
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74 | 74 | If true, Automatically wrap `s` as a LaTeX equation. |
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75 | 75 | color : string |
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76 | 76 | Foreground color name among dvipsnames, e.g. 'Maroon' or on hex RGB |
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77 | 77 | format, e.g. '#AA20FA'. |
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78 | 78 | scale : float |
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79 | 79 | Scale factor for the resulting PNG. |
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80 | 80 | |
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81 | 81 | None is returned when the backend cannot be used. |
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82 | 82 | |
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83 | 83 | """ |
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84 | 84 | s = cast_unicode(s) |
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85 | 85 | allowed_backends = LaTeXTool.instance().backends |
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86 | 86 | if backend is None: |
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87 | 87 | backend = allowed_backends[0] |
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88 | 88 | if backend not in allowed_backends: |
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89 | 89 | return None |
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90 | 90 | if backend == 'matplotlib': |
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91 | 91 | f = latex_to_png_mpl |
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92 | 92 | elif backend == 'dvipng': |
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93 | 93 | f = latex_to_png_dvipng |
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94 | 94 | if color.startswith('#'): |
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95 | 95 | # Convert hex RGB color to LaTeX RGB color. |
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96 | 96 | if len(color) == 7: |
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97 | 97 | try: |
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98 | 98 | color = "RGB {}".format(" ".join([str(int(x, 16)) for x in |
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99 | 99 | textwrap.wrap(color[1:], 2)])) |
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100 | 100 | except ValueError as e: |
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101 | 101 | raise ValueError('Invalid color specification {}.'.format(color)) from e |
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102 | 102 | else: |
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103 | 103 | raise ValueError('Invalid color specification {}.'.format(color)) |
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104 | 104 | else: |
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105 | 105 | raise ValueError('No such backend {0}'.format(backend)) |
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106 | 106 | bin_data = f(s, wrap, color, scale) |
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107 | 107 | if encode and bin_data: |
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108 | 108 | bin_data = encodebytes(bin_data) |
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109 | 109 | return bin_data |
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110 | 110 | |
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111 | 111 | |
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112 | 112 | def latex_to_png_mpl(s, wrap, color='Black', scale=1.0): |
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113 | 113 | try: |
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114 | 114 | from matplotlib import mathtext |
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115 | 115 | from pyparsing import ParseFatalException |
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116 | 116 | except ImportError: |
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117 | 117 | return None |
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118 | 118 | |
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119 | 119 | # mpl mathtext doesn't support display math, force inline |
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120 | 120 | s = s.replace('$$', '$') |
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121 | 121 | if wrap: |
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122 | 122 | s = u'${0}$'.format(s) |
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123 | 123 | |
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124 | 124 | try: |
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125 | 125 | mt = mathtext.MathTextParser('bitmap') |
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126 | 126 | f = BytesIO() |
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127 | 127 | dpi = 120*scale |
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128 | 128 | mt.to_png(f, s, fontsize=12, dpi=dpi, color=color) |
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129 | 129 | return f.getvalue() |
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130 | 130 | except (ValueError, RuntimeError, ParseFatalException): |
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131 | 131 | return None |
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132 | 132 | |
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133 | 133 | |
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134 | 134 | def latex_to_png_dvipng(s, wrap, color='Black', scale=1.0): |
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135 | 135 | try: |
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136 | 136 | find_cmd('latex') |
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137 | 137 | find_cmd('dvipng') |
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138 | 138 | except FindCmdError: |
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139 | 139 | return None |
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140 | 140 | try: |
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141 | 141 | workdir = PurePath(tempfile.mkdtemp()) |
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142 | 142 | tmpfile = workdir.joinpath("tmp.tex") |
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143 | 143 | dvifile = workdir.joinpath("tmp.dvi") |
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144 | 144 | outfile = workdir.joinpath("tmp.png") |
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145 | 145 | |
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146 |
with tmpfile.open("w", encoding= |
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146 | with tmpfile.open("w", encoding="utf8") as f: | |
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147 | 147 | f.writelines(genelatex(s, wrap)) |
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148 | 148 | |
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149 | 149 | with open(os.devnull, 'wb') as devnull: |
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150 | 150 | subprocess.check_call( |
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151 | 151 | ["latex", "-halt-on-error", "-interaction", "batchmode", tmpfile], |
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152 | 152 | cwd=workdir, stdout=devnull, stderr=devnull) |
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153 | 153 | |
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154 | 154 | resolution = round(150*scale) |
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155 | 155 | subprocess.check_call( |
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156 | 156 | ["dvipng", "-T", "tight", "-D", str(resolution), "-z", "9", |
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157 | 157 | "-bg", "transparent", "-o", outfile, dvifile, "-fg", color], |
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158 | 158 | cwd=workdir, stdout=devnull, stderr=devnull) |
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159 | 159 | |
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160 | 160 | with outfile.open("rb") as f: |
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161 | 161 | return f.read() |
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162 | 162 | except subprocess.CalledProcessError: |
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163 | 163 | return None |
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164 | 164 | finally: |
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165 | 165 | shutil.rmtree(workdir) |
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166 | 166 | |
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167 | 167 | |
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168 | 168 | def kpsewhich(filename): |
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169 | 169 | """Invoke kpsewhich command with an argument `filename`.""" |
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170 | 170 | try: |
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171 | 171 | find_cmd("kpsewhich") |
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172 | 172 | proc = subprocess.Popen( |
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173 | 173 | ["kpsewhich", filename], |
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174 | 174 | stdout=subprocess.PIPE, stderr=subprocess.PIPE) |
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175 | 175 | (stdout, stderr) = proc.communicate() |
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176 | 176 | return stdout.strip().decode('utf8', 'replace') |
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177 | 177 | except FindCmdError: |
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178 | 178 | pass |
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179 | 179 | |
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180 | 180 | |
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181 | 181 | def genelatex(body, wrap): |
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182 | 182 | """Generate LaTeX document for dvipng backend.""" |
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183 | 183 | lt = LaTeXTool.instance() |
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184 | 184 | breqn = wrap and lt.use_breqn and kpsewhich("breqn.sty") |
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185 | 185 | yield r'\documentclass{article}' |
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186 | 186 | packages = lt.packages |
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187 | 187 | if breqn: |
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188 | 188 | packages = packages + ['breqn'] |
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189 | 189 | for pack in packages: |
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190 | 190 | yield r'\usepackage{{{0}}}'.format(pack) |
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191 | 191 | yield r'\pagestyle{empty}' |
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192 | 192 | if lt.preamble: |
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193 | 193 | yield lt.preamble |
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194 | 194 | yield r'\begin{document}' |
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195 | 195 | if breqn: |
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196 | 196 | yield r'\begin{dmath*}' |
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197 | 197 | yield body |
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198 | 198 | yield r'\end{dmath*}' |
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199 | 199 | elif wrap: |
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200 | 200 | yield u'$${0}$$'.format(body) |
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201 | 201 | else: |
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202 | 202 | yield body |
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203 | 203 | yield u'\\end{document}' |
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204 | 204 | |
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205 | 205 | |
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206 | 206 | _data_uri_template_png = u"""<img src="data:image/png;base64,%s" alt=%s />""" |
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207 | 207 | |
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208 | 208 | def latex_to_html(s, alt='image'): |
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209 | 209 | """Render LaTeX to HTML with embedded PNG data using data URIs. |
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210 | 210 | |
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211 | 211 | Parameters |
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212 | 212 | ---------- |
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213 | 213 | s : str |
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214 | 214 | The raw string containing valid inline LateX. |
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215 | 215 | alt : str |
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216 | 216 | The alt text to use for the HTML. |
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217 | 217 | """ |
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218 | 218 | base64_data = latex_to_png(s, encode=True).decode('ascii') |
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219 | 219 | if base64_data: |
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220 | 220 | return _data_uri_template_png % (base64_data, alt) |
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221 | 221 | |
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222 | 222 |
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