from __future__ import print_function, division
from os.path import join
import tempfile
import shutil
import io
from io import BytesIO
try:
from subprocess import STDOUT, CalledProcessError, check_output
except ImportError:
pass
from sympy.core.compatibility import unicode, u_decode
from sympy.utilities.exceptions import SymPyDeprecationWarning
from sympy.utilities.misc import find_executable
from .latex import latex
from sympy.utilities.decorator import doctest_depends_on
@doctest_depends_on(exe=('latex', 'dvipng'), modules=('pyglet',),
disable_viewers=('evince', 'gimp', 'superior-dvi-viewer'))
[docs]def preview(expr, output='png', viewer=None, euler=True, packages=(),
filename=None, outputbuffer=None, preamble=None, dvioptions=None,
outputTexFile=None, **latex_settings):
r"""
View expression or LaTeX markup in PNG, DVI, PostScript or PDF form.
If the expr argument is an expression, it will be exported to LaTeX and
then compiled using the available TeX distribution. The first argument,
'expr', may also be a LaTeX string. The function will then run the
appropriate viewer for the given output format or use the user defined
one. By default png output is generated.
By default pretty Euler fonts are used for typesetting (they were used to
typeset the well known "Concrete Mathematics" book). For that to work, you
need the 'eulervm.sty' LaTeX style (in Debian/Ubuntu, install the
texlive-fonts-extra package). If you prefer default AMS fonts or your
system lacks 'eulervm' LaTeX package then unset the 'euler' keyword
argument.
To use viewer auto-detection, lets say for 'png' output, issue
>>> from sympy import symbols, preview, Symbol
>>> x, y = symbols("x,y")
>>> preview(x + y, output='png')
This will choose 'pyglet' by default. To select a different one, do
>>> preview(x + y, output='png', viewer='gimp')
The 'png' format is considered special. For all other formats the rules
are slightly different. As an example we will take 'dvi' output format. If
you would run
>>> preview(x + y, output='dvi')
then 'view' will look for available 'dvi' viewers on your system
(predefined in the function, so it will try evince, first, then kdvi and
xdvi). If nothing is found you will need to set the viewer explicitly.
>>> preview(x + y, output='dvi', viewer='superior-dvi-viewer')
This will skip auto-detection and will run user specified
'superior-dvi-viewer'. If 'view' fails to find it on your system it will
gracefully raise an exception.
You may also enter 'file' for the viewer argument. Doing so will cause
this function to return a file object in read-only mode, if 'filename'
is unset. However, if it was set, then 'preview' writes the genereted
file to this filename instead.
There is also support for writing to a BytesIO like object, which needs
to be passed to the 'outputbuffer' argument.
>>> from io import BytesIO
>>> obj = BytesIO()
>>> preview(x + y, output='png', viewer='BytesIO',
... outputbuffer=obj)
The LaTeX preamble can be customized by setting the 'preamble' keyword
argument. This can be used, e.g., to set a different font size, use a
custom documentclass or import certain set of LaTeX packages.
>>> preamble = "\\documentclass[10pt]{article}\n" \
... "\\usepackage{amsmath,amsfonts}\\begin{document}"
>>> preview(x + y, output='png', preamble=preamble)
If the value of 'output' is different from 'dvi' then command line
options can be set ('dvioptions' argument) for the execution of the
'dvi'+output conversion tool. These options have to be in the form of a
list of strings (see subprocess.Popen).
Additional keyword args will be passed to the latex call, e.g., the
symbol_names flag.
>>> phidd = Symbol('phidd')
>>> preview(phidd, symbol_names={phidd:r'\ddot{\varphi}'})
For post-processing the generated TeX File can be written to a file by
passing the desired filename to the 'outputTexFile' keyword
argument. To write the TeX code to a file named
"sample.tex" and run the default png viewer to display the resulting
bitmap, do
>>> preview(x + y, outputTexFile="sample.tex")
"""
special = [ 'pyglet' ]
if viewer is None:
if output == "png":
viewer = "pyglet"
else:
# sorted in order from most pretty to most ugly
# very discussable, but indeed 'gv' looks awful :)
# TODO add candidates for windows to list
candidates = {
"dvi": [ "evince", "okular", "kdvi", "xdvi" ],
"ps": [ "evince", "okular", "gsview", "gv" ],
"pdf": [ "evince", "okular", "kpdf", "acroread", "xpdf", "gv" ],
}
try:
for candidate in candidates[output]:
path = find_executable(candidate)
if path is not None:
viewer = path
break
else:
raise SystemError(
"No viewers found for '%s' output format." % output)
except KeyError:
raise SystemError("Invalid output format: %s" % output)
else:
if viewer == "file":
if filename is None:
SymPyDeprecationWarning(feature="Using viewer=\"file\" without a "
"specified filename", deprecated_since_version="0.7.3",
useinstead="viewer=\"file\" and filename=\"desiredname\"",
issue=7018).warn()
elif viewer == "StringIO":
SymPyDeprecationWarning(feature="The preview() viewer StringIO",
useinstead="BytesIO", deprecated_since_version="0.7.4",
issue=7083).warn()
viewer = "BytesIO"
if outputbuffer is None:
raise ValueError("outputbuffer has to be a BytesIO "
"compatible object if viewer=\"StringIO\"")
elif viewer == "BytesIO":
if outputbuffer is None:
raise ValueError("outputbuffer has to be a BytesIO "
"compatible object if viewer=\"BytesIO\"")
elif viewer not in special and not find_executable(viewer):
raise SystemError("Unrecognized viewer: %s" % viewer)
if preamble is None:
actual_packages = packages + ("amsmath", "amsfonts")
if euler:
actual_packages += ("euler",)
package_includes = "\n" + "\n".join(["\\usepackage{%s}" % p
for p in actual_packages])
preamble = r"""\documentclass[12pt]{article}
\pagestyle{empty}
%s
\begin{document}
""" % (package_includes)
else:
if len(packages) > 0:
raise ValueError("The \"packages\" keyword must not be set if a "
"custom LaTeX preamble was specified")
latex_main = preamble + '\n%s\n\n' + r"\end{document}"
if isinstance(expr, str):
latex_string = expr
else:
latex_string = latex(expr, mode='inline', **latex_settings)
try:
workdir = tempfile.mkdtemp()
with io.open(join(workdir, 'texput.tex'), 'w', encoding='utf-8') as fh:
fh.write(unicode(latex_main) % u_decode(latex_string))
if outputTexFile is not None:
shutil.copyfile(join(workdir, 'texput.tex'), outputTexFile)
if not find_executable('latex'):
raise RuntimeError("latex program is not installed")
try:
check_output(['latex', '-halt-on-error', '-interaction=nonstopmode',
'texput.tex'], cwd=workdir, stderr=STDOUT)
except CalledProcessError as e:
raise RuntimeError(
"'latex' exited abnormally with the following output:\n%s" %
e.output)
if output != "dvi":
defaultoptions = {
"ps": [],
"pdf": [],
"png": ["-T", "tight", "-z", "9", "--truecolor"],
"svg": ["--no-fonts"],
}
commandend = {
"ps": ["-o", "texput.ps", "texput.dvi"],
"pdf": ["texput.dvi", "texput.pdf"],
"png": ["-o", "texput.png", "texput.dvi"],
"svg": ["-o", "texput.svg", "texput.dvi"],
}
if output == "svg":
cmd = ["dvisvgm"]
else:
cmd = ["dvi" + output]
if not find_executable(cmd[0]):
raise RuntimeError("%s is not installed" % cmd[0])
try:
if dvioptions is not None:
cmd.extend(dvioptions)
else:
cmd.extend(defaultoptions[output])
cmd.extend(commandend[output])
except KeyError:
raise SystemError("Invalid output format: %s" % output)
try:
check_output(cmd, cwd=workdir, stderr=STDOUT)
except CalledProcessError as e:
raise RuntimeError(
"'%s' exited abnormally with the following output:\n%s" %
(' '.join(cmd), e.output))
src = "texput.%s" % (output)
if viewer == "file":
if filename is None:
buffer = BytesIO()
with open(join(workdir, src), 'rb') as fh:
buffer.write(fh.read())
return buffer
else:
shutil.move(join(workdir,src), filename)
elif viewer == "BytesIO":
with open(join(workdir, src), 'rb') as fh:
outputbuffer.write(fh.read())
elif viewer == "pyglet":
try:
from pyglet import window, image, gl
from pyglet.window import key
except ImportError:
raise ImportError("pyglet is required for preview.\n visit http://www.pyglet.org/")
if output == "png":
from pyglet.image.codecs.png import PNGImageDecoder
img = image.load(join(workdir, src), decoder=PNGImageDecoder())
else:
raise SystemError("pyglet preview works only for 'png' files.")
offset = 25
config = gl.Config(double_buffer=False)
win = window.Window(
width=img.width + 2*offset,
height=img.height + 2*offset,
caption="sympy",
resizable=False,
config=config
)
win.set_vsync(False)
try:
def on_close():
win.has_exit = True
win.on_close = on_close
def on_key_press(symbol, modifiers):
if symbol in [key.Q, key.ESCAPE]:
on_close()
win.on_key_press = on_key_press
def on_expose():
gl.glClearColor(1.0, 1.0, 1.0, 1.0)
gl.glClear(gl.GL_COLOR_BUFFER_BIT)
img.blit(
(win.width - img.width) / 2,
(win.height - img.height) / 2
)
win.on_expose = on_expose
while not win.has_exit:
win.dispatch_events()
win.flip()
except KeyboardInterrupt:
pass
win.close()
else:
try:
check_output([viewer, src], cwd=workdir, stderr=STDOUT)
except CalledProcessError as e:
raise RuntimeError(
"'%s %s' exited abnormally with the following output:\n%s" %
(viewer, src, e.output))
finally:
try:
shutil.rmtree(workdir) # delete directory
except OSError as e:
if e.errno != 2: # code 2 - no such file or directory
raise
