Merge pull request #13372 from bnavigator/latex-png-bg-transparency

use full-alpha transparency on dvipng rendered LaTeX

IPython/lib/latextools.py

@@ -1,230 +1,247 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
 import textwrap
 
 from pathlib import Path, PurePath
 
 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, color='Black',
                  scale=1.0):
     """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, e.g. 'Maroon' or on hex RGB
         format, e.g. '#AA20FA'.
     scale : float
         Scale factor for the resulting PNG.
 
     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
         if color.startswith('#'):
             # Convert hex RGB color to LaTeX RGB color.
             if len(color) == 7:
                 try:
                     color = "RGB {}".format(" ".join([str(int(x, 16)) for x in
                                                       textwrap.wrap(color[1:], 2)]))
                 except ValueError as e:
                     raise ValueError('Invalid color specification {}.'.format(color)) from e
             else:
                 raise ValueError('Invalid color specification {}.'.format(color))
     else:
         raise ValueError('No such backend {0}'.format(backend))
     bin_data = f(s, wrap, color, scale)
     if encode and bin_data:
         bin_data = encodebytes(bin_data)
     return bin_data
 
 
 def latex_to_png_mpl(s, wrap, color='Black', scale=1.0):
     try:
         from matplotlib import figure, font_manager, mathtext
         from matplotlib.backends import backend_agg
         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:
         prop = font_manager.FontProperties(size=12)
         dpi = 120 * scale
         buffer = BytesIO()
 
         # Adapted from mathtext.math_to_image
         parser = mathtext.MathTextParser("path")
         width, height, depth, _, _ = parser.parse(s, dpi=72, prop=prop)
         fig = figure.Figure(figsize=(width / 72, height / 72))
         fig.text(0, depth / height, s, fontproperties=prop, color=color)
         backend_agg.FigureCanvasAgg(fig)
         fig.savefig(buffer, dpi=dpi, format="png", transparent=True)
         return buffer.getvalue()
     except (ValueError, RuntimeError, ParseFatalException):
         return None
 
 
 def latex_to_png_dvipng(s, wrap, color='Black', scale=1.0):
     try:
         find_cmd('latex')
         find_cmd('dvipng')
     except FindCmdError:
         return None
     try:
         workdir = Path(tempfile.mkdtemp())
         tmpfile = workdir.joinpath("tmp.tex")
         dvifile = workdir.joinpath("tmp.dvi")
         outfile = workdir.joinpath("tmp.png")
 
         with tmpfile.open("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)
 
             resolution = round(150*scale)
             subprocess.check_call(
-                ["dvipng", "-T", "tight", "-D", str(resolution), "-z", "9",
-                 "-bg", "transparent", "-o", outfile, dvifile, "-fg", color],
-                 cwd=workdir, stdout=devnull, stderr=devnull)
+                [
+                    "dvipng",
+                    "-T",
+                    "tight",
+                    "-D",
+                    str(resolution),
+                    "-z",
+                    "9",
+                    "-bg",
+                    "Transparent",
+                    "-o",
+                    outfile,
+                    dvifile,
+                    "-fg",
+                    color,
+                ],
+                cwd=workdir,
+                stdout=devnull,
+                stderr=devnull,
+            )
 
         with outfile.open("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/utils/timing.py

@@ -1,123 +1,122 b''
 # encoding: utf-8
 """
 Utilities for timing code execution.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import time
 
 #-----------------------------------------------------------------------------
 # Code
 #-----------------------------------------------------------------------------
 
 # If possible (Unix), use the resource module instead of time.clock()
 try:
     import resource
 except ImportError:
     resource = None
 
 # Some implementations (like jyputerlite) don't have getrusage
 if resource is not None and hasattr(resource, "getrusage"):
     def clocku():
         """clocku() -> floating point number
 
         Return the *USER* CPU time in seconds since the start of the process.
         This is done via a call to resource.getrusage, so it avoids the
         wraparound problems in time.clock()."""
 
         return resource.getrusage(resource.RUSAGE_SELF)[0]
 
     def clocks():
         """clocks() -> floating point number
 
         Return the *SYSTEM* CPU time in seconds since the start of the process.
         This is done via a call to resource.getrusage, so it avoids the
         wraparound problems in time.clock()."""
 
         return resource.getrusage(resource.RUSAGE_SELF)[1]
 
     def clock():
         """clock() -> floating point number
 
         Return the *TOTAL USER+SYSTEM* CPU time in seconds since the start of
         the process.  This is done via a call to resource.getrusage, so it
         avoids the wraparound problems in time.clock()."""
 
         u,s = resource.getrusage(resource.RUSAGE_SELF)[:2]
         return u+s
 
     def clock2():
         """clock2() -> (t_user,t_system)
 
         Similar to clock(), but return a tuple of user/system times."""
         return resource.getrusage(resource.RUSAGE_SELF)[:2]
 
-
 else:
     # There is no distinction of user/system time under windows, so we just use
     # time.perff_counter() for everything...
     clocku = clocks = clock = time.perf_counter
     def clock2():
         """Under windows, system CPU time can't be measured.
 
         This just returns perf_counter() and zero."""
         return time.perf_counter(),0.0
 
     
 def timings_out(reps,func,*args,**kw):
     """timings_out(reps,func,*args,**kw) -> (t_total,t_per_call,output)
 
     Execute a function reps times, return a tuple with the elapsed total
     CPU time in seconds, the time per call and the function's output.
 
     Under Unix, the return value is the sum of user+system time consumed by
     the process, computed via the resource module.  This prevents problems
     related to the wraparound effect which the time.clock() function has.
 
     Under Windows the return value is in wall clock seconds. See the
     documentation for the time module for more details."""
 
     reps = int(reps)
     assert reps >=1, 'reps must be >= 1'
     if reps==1:
         start = clock()
         out = func(*args,**kw)
         tot_time = clock()-start
     else:
         rng = range(reps-1) # the last time is executed separately to store output
         start = clock()
         for dummy in rng: func(*args,**kw)
         out = func(*args,**kw)  # one last time
         tot_time = clock()-start
     av_time = tot_time / reps
     return tot_time,av_time,out
 
 
 def timings(reps,func,*args,**kw):
     """timings(reps,func,*args,**kw) -> (t_total,t_per_call)
 
     Execute a function reps times, return a tuple with the elapsed total CPU
     time in seconds and the time per call. These are just the first two values
     in timings_out()."""
 
     return timings_out(reps,func,*args,**kw)[0:2]
 
 
 def timing(func,*args,**kw):
     """timing(func,*args,**kw) -> t_total
 
     Execute a function once, return the elapsed total CPU time in
     seconds. This is just the first value in timings_out()."""
 
     return timings_out(1,func,*args,**kw)[0]