Enable changing the font color for LaTeX rendering

IPython/lib/latextools.py

@@ -1,201 +1,203 b''
 # -*- coding: utf-8 -*-
 """Tools for handling LaTeX."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 from io import BytesIO, open
 import os
 import tempfile
 import shutil
 import subprocess
 from base64 import encodebytes
 
 from IPython.utils.process import find_cmd, FindCmdError
 from traitlets.config import get_config
 from traitlets.config.configurable import SingletonConfigurable
 from traitlets import List, Bool, Unicode
 from IPython.utils.py3compat import cast_unicode
 
 
 class LaTeXTool(SingletonConfigurable):
     """An object to store configuration of the LaTeX tool."""
     def _config_default(self):
         return get_config()
-    
+
     backends = List(
         Unicode(), ["matplotlib", "dvipng"],
         help="Preferred backend to draw LaTeX math equations. "
         "Backends in the list are checked one by one and the first "
         "usable one is used.  Note that `matplotlib` backend "
         "is usable only for inline style equations.  To draw  "
         "display style equations, `dvipng` backend must be specified. ",
         # It is a List instead of Enum, to make configuration more
         # flexible.  For example, to use matplotlib mainly but dvipng
         # for display style, the default ["matplotlib", "dvipng"] can
         # be used.  To NOT use dvipng so that other repr such as
         # unicode pretty printing is used, you can use ["matplotlib"].
         ).tag(config=True)
 
     use_breqn = Bool(
         True,
         help="Use breqn.sty to automatically break long equations. "
         "This configuration takes effect only for dvipng backend.",
         ).tag(config=True)
 
     packages = List(
         ['amsmath', 'amsthm', 'amssymb', 'bm'],
         help="A list of packages to use for dvipng backend. "
         "'breqn' will be automatically appended when use_breqn=True.",
         ).tag(config=True)
 
     preamble = Unicode(
         help="Additional preamble to use when generating LaTeX source "
         "for dvipng backend.",
         ).tag(config=True)
 
 
-def latex_to_png(s, encode=False, backend=None, wrap=False):
+def latex_to_png(s, encode=False, backend=None, wrap=False, color='Black'):
     """Render a LaTeX string to PNG.
 
     Parameters
     ----------
     s : str
         The raw string containing valid inline LaTeX.
     encode : bool, optional
         Should the PNG data base64 encoded to make it JSON'able.
     backend : {matplotlib, dvipng}
         Backend for producing PNG data.
     wrap : bool
         If true, Automatically wrap `s` as a LaTeX equation.
+    color : string
+        Foreground color name among dvipsnames.
 
     None is returned when the backend cannot be used.
 
     """
     s = cast_unicode(s)
     allowed_backends = LaTeXTool.instance().backends
     if backend is None:
         backend = allowed_backends[0]
     if backend not in allowed_backends:
         return None
     if backend == 'matplotlib':
         f = latex_to_png_mpl
     elif backend == 'dvipng':
         f = latex_to_png_dvipng
     else:
         raise ValueError('No such backend {0}'.format(backend))
-    bin_data = f(s, wrap)
+    bin_data = f(s, wrap, color)
     if encode and bin_data:
         bin_data = encodebytes(bin_data)
     return bin_data
 
 
-def latex_to_png_mpl(s, wrap):
+def latex_to_png_mpl(s, wrap, color='Black'):
     try:
         from matplotlib import mathtext
         from pyparsing import ParseFatalException
     except ImportError:
         return None
 
     # mpl mathtext doesn't support display math, force inline
     s = s.replace('$$', '$')
     if wrap:
         s = u'${0}$'.format(s)
 
     try:
         mt = mathtext.MathTextParser('bitmap')
         f = BytesIO()
-        mt.to_png(f, s, fontsize=12)
+        mt.to_png(f, s, fontsize=12, color=color)
         return f.getvalue()
     except (ValueError, RuntimeError, ParseFatalException):
         return None
 
 
-def latex_to_png_dvipng(s, wrap):
+def latex_to_png_dvipng(s, wrap, color='Black'):
     try:
         find_cmd('latex')
         find_cmd('dvipng')
     except FindCmdError:
         return None
     try:
         workdir = tempfile.mkdtemp()
         tmpfile = os.path.join(workdir, "tmp.tex")
         dvifile = os.path.join(workdir, "tmp.dvi")
         outfile = os.path.join(workdir, "tmp.png")
 
         with open(tmpfile, "w", encoding='utf8') as f:
             f.writelines(genelatex(s, wrap))
 
         with open(os.devnull, 'wb') as devnull:
             subprocess.check_call(
                 ["latex", "-halt-on-error", "-interaction", "batchmode", tmpfile],
                 cwd=workdir, stdout=devnull, stderr=devnull)
 
             subprocess.check_call(
                 ["dvipng", "-T", "tight", "-x", "1500", "-z", "9",
-                 "-bg", "transparent", "-o", outfile, dvifile], cwd=workdir,
-                stdout=devnull, stderr=devnull)
+                 "-bg", "transparent", "-o", outfile, dvifile, "-fg", color],
+                 cwd=workdir, stdout=devnull, stderr=devnull)
 
         with open(outfile, "rb") as f:
             return f.read()
     except subprocess.CalledProcessError:
         return None
     finally:
         shutil.rmtree(workdir)
 
 
 def kpsewhich(filename):
     """Invoke kpsewhich command with an argument `filename`."""
     try:
         find_cmd("kpsewhich")
         proc = subprocess.Popen(
             ["kpsewhich", filename],
             stdout=subprocess.PIPE, stderr=subprocess.PIPE)
         (stdout, stderr) = proc.communicate()
         return stdout.strip().decode('utf8', 'replace')
     except FindCmdError:
         pass
 
 
 def genelatex(body, wrap):
     """Generate LaTeX document for dvipng backend."""
     lt = LaTeXTool.instance()
     breqn = wrap and lt.use_breqn and kpsewhich("breqn.sty")
     yield r'\documentclass{article}'
     packages = lt.packages
     if breqn:
         packages = packages + ['breqn']
     for pack in packages:
         yield r'\usepackage{{{0}}}'.format(pack)
     yield r'\pagestyle{empty}'
     if lt.preamble:
         yield lt.preamble
     yield r'\begin{document}'
     if breqn:
         yield r'\begin{dmath*}'
         yield body
         yield r'\end{dmath*}'
     elif wrap:
         yield u'$${0}$$'.format(body)
     else:
         yield body
     yield u'\\end{document}'
 
 
 _data_uri_template_png = u"""<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).decode('ascii')
     if base64_data:
         return _data_uri_template_png  % (base64_data, alt)
 
 

IPython/lib/tests/test_latextools.py

@@ -1,134 +1,157 b''
 # encoding: utf-8
 """Tests for IPython.utils.path.py"""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 from unittest.mock import patch
 import nose.tools as nt
 
 from IPython.lib import latextools
 from IPython.testing.decorators import onlyif_cmds_exist, skipif_not_matplotlib
 from IPython.utils.process import FindCmdError
 
 
 def test_latex_to_png_dvipng_fails_when_no_cmd():
     """
     `latex_to_png_dvipng` should return None when there is no required command
     """
     for command in ['latex', 'dvipng']:
         yield (check_latex_to_png_dvipng_fails_when_no_cmd, command)
 
 
 def check_latex_to_png_dvipng_fails_when_no_cmd(command):
     def mock_find_cmd(arg):
         if arg == command:
             raise FindCmdError
 
     with patch.object(latextools, "find_cmd", mock_find_cmd):
         nt.assert_equal(latextools.latex_to_png_dvipng("whatever", True),
                          None)
 
 
 @onlyif_cmds_exist('latex', 'dvipng')
 def test_latex_to_png_dvipng_runs():
     """
     Test that latex_to_png_dvipng just runs without error.
     """
     def mock_kpsewhich(filename):
         nt.assert_equal(filename, "breqn.sty")
         return None
 
     for (s, wrap) in [(u"$$x^2$$", False), (u"x^2", True)]:
         yield (latextools.latex_to_png_dvipng, s, wrap)
 
         with patch.object(latextools, "kpsewhich", mock_kpsewhich):
             yield (latextools.latex_to_png_dvipng, s, wrap)
 
 @skipif_not_matplotlib
 def test_latex_to_png_mpl_runs():
     """
     Test that latex_to_png_mpl just runs without error.
     """
     def mock_kpsewhich(filename):
         nt.assert_equal(filename, "breqn.sty")
         return None
 
     for (s, wrap) in [("$x^2$", False), ("x^2", True)]:
         yield (latextools.latex_to_png_mpl, s, wrap)
 
         with patch.object(latextools, "kpsewhich", mock_kpsewhich):
             yield (latextools.latex_to_png_mpl, s, wrap)
 
 @skipif_not_matplotlib
 def test_latex_to_html():
     img = latextools.latex_to_html("$x^2$")
-    nt.assert_in("data:image/png;base64,iVBOR", img) 
+    nt.assert_in("data:image/png;base64,iVBOR", img)
 
 
 def test_genelatex_no_wrap():
     """
     Test genelatex with wrap=False.
     """
     def mock_kpsewhich(filename):
         assert False, ("kpsewhich should not be called "
                        "(called with {0})".format(filename))
 
     with patch.object(latextools, "kpsewhich", mock_kpsewhich):
         nt.assert_equal(
             '\n'.join(latextools.genelatex("body text", False)),
             r'''\documentclass{article}
 \usepackage{amsmath}
 \usepackage{amsthm}
 \usepackage{amssymb}
 \usepackage{bm}
 \pagestyle{empty}
 \begin{document}
 body text
 \end{document}''')
 
 
 def test_genelatex_wrap_with_breqn():
     """
     Test genelatex with wrap=True for the case breqn.sty is installed.
     """
     def mock_kpsewhich(filename):
         nt.assert_equal(filename, "breqn.sty")
         return "path/to/breqn.sty"
 
     with patch.object(latextools, "kpsewhich", mock_kpsewhich):
         nt.assert_equal(
             '\n'.join(latextools.genelatex("x^2", True)),
             r'''\documentclass{article}
 \usepackage{amsmath}
 \usepackage{amsthm}
 \usepackage{amssymb}
 \usepackage{bm}
 \usepackage{breqn}
 \pagestyle{empty}
 \begin{document}
 \begin{dmath*}
 x^2
 \end{dmath*}
 \end{document}''')
 
 
 def test_genelatex_wrap_without_breqn():
     """
     Test genelatex with wrap=True for the case breqn.sty is not installed.
     """
     def mock_kpsewhich(filename):
         nt.assert_equal(filename, "breqn.sty")
         return None
 
     with patch.object(latextools, "kpsewhich", mock_kpsewhich):
         nt.assert_equal(
             '\n'.join(latextools.genelatex("x^2", True)),
             r'''\documentclass{article}
 \usepackage{amsmath}
 \usepackage{amsthm}
 \usepackage{amssymb}
 \usepackage{bm}
 \pagestyle{empty}
 \begin{document}
 $$x^2$$
 \end{document}''')
+
+
+def test_latex_to_png_color():
+    """
+    Test color settings for latex_to_png.
+    """
+    latex_string = "$x^2$"
+    default_value = latextools.latex_to_png(latex_string, wrap=False)
+    dvipng_default = latextools.latex_to_png_dvipng(latex_string, False)
+    dvipng_black = latextools.latex_to_png_dvipng(latex_string, False, 'Black')
+    nt.assert_equal(dvipng_default, dvipng_black)
+    mpl_default = latextools.latex_to_png_mpl(latex_string, False)
+    mpl_black = latextools.latex_to_png_mpl(latex_string, False, 'Black')
+    nt.assert_equal(mpl_default, mpl_black)
+    nt.assert_in(default_value, [dvipng_black, mpl_black])
+
+    # Test that dvips name colors can be used without error
+    dvipng_maroon = latextools.latex_to_png_dvipng(latex_string, False, 'Maroon')
+    # And that it doesn't return the black one
+    nt.assert_not_equal(dvipng_black, dvipng_maroon)
+
+    mpl_maroon = latextools.latex_to_png_mpl(latex_string, False, 'Maroon')
+    nt.assert_not_equal(mpl_black, mpl_maroon)