Renders LaTeX for Github Readmes
![\begin{tikzpicture}
\newcounter{density}
\setcounter{density}{20}
\def\couleur{blue}
\path[coordinate] (0,0) coordinate(A)
++( 60:6cm) coordinate(B)
++(-60:6cm) coordinate(C);
\draw[fill=\couleur!\thedensity] (A) -- (B) -- (C) -- cycle;
\foreach \x in {1,...,15}{%
\pgfmathsetcounter{density}{\thedensity+10}
\setcounter{density}{\thedensity}
\path[coordinate] coordinate(X) at (A){};
\path[coordinate] (A) -- (B) coordinate[pos=.15](A)
-- (C) coordinate[pos=.15](B)
-- (X) coordinate[pos=.15](C);
\draw[fill=\couleur!\thedensity] (A)--(B)--(C)--cycle;
}
\end{tikzpicture}](svgs/a00f34be6b1ce8e4820c9852c5e6163e.png)
Make sure that pdflatex is installed on your system.
readme2tex is a Python script that "texifies" your readme. It takes in Github Markdown and
replaces anything enclosed between dollar signs with rendered 
.
In addition, while other Github TeX renderers tend to give a jumpy look to the compiled text,
readme2tex ensures that inline mathematical expressions
are properly aligned with the rest of the text to give a more natural look to the document. For example,
this formula 
is preprocessed so that it lines up at the correct baseline for the text.
This is the one salient feature of this package compared to the others out there.
Make sure that you have Python 2.7 or above and pip installed. In addition, you'll need to have the programs latex
and dvisvgm on your PATH. In addition, you'll need to pre-install the geometry package in .
To install readme2tex, you'll need to run
sudo pip install readme2texor, if you want to try out the bleeding edge,
git clone https://github.com/leegao/readme2tex
cd readme2tex
python setup.py developTo compile INPUT.md and render all of its formulas, run
python -m readme2tex --output README.md INPUT.mdIf you want to do this automatically for every commit of INPUT.md, you can use the --add-git-hook command once to
set up the post-commit hook, like so
git stash --include-untracked
git branch svgs # if this isn't already there
python -m readme2tex --output README.md --branch svgs --usepackage tikz INPUT.md --add-git-hook
# modify INPUT.md
git add INPUT.md
git commit -a -m "updated readme"
git stash popand every git commit that touches INPUT.md from now on will allow you to automatically run readme2tex on it, saving
you from having to remember how readme2tex works. The caveat is that if you use a GUI to interact with git, things
might get a bit wonky. In particular, readme2tex will just assume that you're fine with all of the changes and won't
prompt you for verification like it does on the terminal.
You can uninstall the hook by deleting .git/hooks/post-commit. See python -m readme2tex --help for a list
of what you can do in readme2tex.
Here's a display level formula
The code that was used to render this formula is just
$$
\frac{n!}{k!(n-k)!} = {n \choose k}
$$
Note: you can escape $ so that they don't render.
Here's an inline formula.
It is well known that if
, then
.
The code that was used to render this is:
It is well known that if $ax^2 + bx + c = 0$, then $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$.
Notice that the formulas line up with the baseline of the text, even when the height of these two images are different.
Sometimes, you might run into formulas that are bottom-heavy, like 
. Here, readme2tex
can compute the correct offset to align this formula to the baseline of your paragraph of text as well.
Tikz (Courtesy of http://www.texample.net/)
Did you notice the picture at the top of this page? That was also generated by . readme2tex is capable of
handling Tikz code. For reference, the picture
![\begin{tikzpicture}
\newcounter{density}
\setcounter{density}{20}
\def\couleur{red}
\path[coordinate] (0,0) coordinate(A)
++( 60:6cm) coordinate(B)
++(-60:6cm) coordinate(C);
\draw[fill=\couleur!\thedensity] (A) -- (B) -- (C) -- cycle;
\foreach \x in {1,...,15}{%
\pgfmathsetcounter{density}{\thedensity+10}
\setcounter{density}{\thedensity}
\path[coordinate] coordinate(X) at (A){};
\path[coordinate] (A) -- (B) coordinate[pos=.15](A)
-- (C) coordinate[pos=.15](B)
-- (X) coordinate[pos=.15](C);
\draw[fill=\couleur!\thedensity] (A)--(B)--(C)--cycle;
}
\end{tikzpicture}](svgs/522cbfbc866df378cb95b2ef083131b2.png)
is given by the tikz code
\begin{tikzpicture}
\newcounter{density}
\setcounter{density}{20}
\def\couleur{red}
\path[coordinate] (0,0) coordinate(A)
++( 60:6cm) coordinate(B)
++(-60:6cm) coordinate(C);
\draw[fill=\couleur!\thedensity] (A) -- (B) -- (C) -- cycle;
\foreach \x in {1,...,15}{%
\pgfmathsetcounter{density}{\thedensity+10}
\setcounter{density}{\thedensity}
\path[coordinate] coordinate(X) at (A){};
\path[coordinate] (A) -- (B) coordinate[pos=.15](A)
-- (C) coordinate[pos=.15](B)
-- (X) coordinate[pos=.15](C);
\draw[fill=\couleur!\thedensity] (A)--(B)--(C)--cycle;
}
\end{tikzpicture}
We can see a few other examples, such as this graphical proof of the Pythagorean Theorem.
![\begin{tikzpicture}
\newcommand{\pythagwidth}{3cm}
\newcommand{\pythagheight}{2cm}
\coordinate [label={below right:$A$}] (A) at (0, 0);
\coordinate [label={above right:$B$}] (B) at (0, \pythagheight);
\coordinate [label={below left:$C$}] (C) at (-\pythagwidth, 0);
\coordinate (D1) at (-\pythagheight, \pythagheight + \pythagwidth);
\coordinate (D2) at (-\pythagheight - \pythagwidth, \pythagwidth);
\draw [very thick] (A) -- (C) -- (B) -- (A);
\newcommand{\ranglesize}{0.3cm}
\draw (A) -- ++ (0, \ranglesize) -- ++ (-\ranglesize, 0) -- ++ (0, -\ranglesize);
\draw [dashed] (A) -- node [below] {$b$} ++ (-\pythagwidth, 0)
-- node [right] {$b$} ++ (0, -\pythagwidth)
-- node [above] {$b$} ++ (\pythagwidth, 0)
-- node [left] {$b$} ++ (0, \pythagwidth);
\draw [dashed] (A) -- node [right] {$c$} ++ (0, \pythagheight)
-- node [below] {$c$} ++ (\pythagheight, 0)
-- node [left] {$c$} ++ (0, -\pythagheight)
-- node [above] {$c$} ++ (-\pythagheight, 0);
\draw [dashed] (C) -- node [above left] {$a$} (B)
-- node [below left] {$a$} (D1)
-- node [below right] {$a$} (D2)
-- node [above right] {$a$} (C);
\end{tikzpicture}](svgs/e148d2d3bb31215788cc03f9b472e5ba.png?invert_in_darkmode)
How about a few snowflakes?
![\begin{center}
\usetikzlibrary{lindenmayersystems}
\pgfdeclarelindenmayersystem{A}{
\rule{F -> FF[+F][-F]}
}
\pgfdeclarelindenmayersystem{B}{
\rule{F -> ffF[++FF][--FF]}
}
\pgfdeclarelindenmayersystem{C}{
\symbol{G}{\pgflsystemdrawforward}
\rule{F -> F[+F][-F]FG[+F][-F]FG}
}
\pgfdeclarelindenmayersystem{D}{
\symbol{G}{\pgflsystemdrawforward}
\symbol{H}{\pgflsystemdrawforward}
\rule{F -> H[+HG][-HG]G}
\rule{G -> HF}
}
\tikzset{
type/.style={l-system={#1, axiom=F,order=3,step=4pt,angle=60},
blue, opacity=0.4, line width=.5mm, line cap=round
},
}
\newcommand\drawsnowflake[2][scale=0.2]{
\tikz[#1]
\foreach \a in {0,60,...,300} {
\draw[rotate=\a,#2] l-system;
};
}
\foreach \width in {.2,.4,...,.8}
{ \drawsnowflake[scale=0.3]{type=A, line width=\width mm} }
\foreach \width in {.2,.4,...,.8}
{ \drawsnowflake[scale=0.38]{type=A, l-system={angle=90}, line width=\width mm} }
\foreach \width in {.2,.4,...,.8}
{ \drawsnowflake[scale=0.3]{type=B, line width=\width mm} }
\foreach \width in {.2,.4,...,.8}
{ \drawsnowflake{type=B, l-system={angle=30}, line width=\width mm} }
\drawsnowflake[scale=0.24]{type=C, l-system={order=2}, line width=0.2mm}
\drawsnowflake[scale=0.25]{type=C, l-system={order=2}, line width=0.4mm}
\drawsnowflake[scale=0.25]{type=C, l-system={order=2,axiom=fF}, line width=0.2mm}
\drawsnowflake[scale=0.32]{type=C, l-system={order=2,axiom=---fff+++F}, line width=0.2mm}
\drawsnowflake[scale=0.38]{type=D, l-system={order=4,angle=60,axiom=GF}, line width=0.7mm}
\drawsnowflake[scale=0.38]{type=D, l-system={order=4,angle=60,axiom=GfF}, line width=0.7mm}
\drawsnowflake[scale=0.38]{type=D, l-system={order=4,angle=60,axiom=FG}, line width=0.7mm}
\drawsnowflake[scale=0.38]{type=D, l-system={order=4,angle=60,axiom=FfG}, line width=0.7mm}
\end{center}](svgs/eb57748cb91d08bfc997b0d70f7f2774.png?invert_in_darkmode)
python -m readme2tex --output README.md [READOTHER.md]
It will then look for a file called readother.md and compile it down to a readable Github-ready
document.
In addition, you can specify other arguments to render.py, such as:
--readme READOTHER.mdThe raw readme to process. Defaults toREADOTHER.md.--output README.mdThe processed readme.md file. Defaults toREADME_GH.md.--usepackage tikzAddition packages to use during compilation. You can specify this multiple times.--svgdir svgs/The directory to store the output svgs. The default issvgs/--branch masterExperimental Which branch to store the svgs into, the default is just master.--username usernameYour github username. This is optional, andrender.pywill try to infer this for you.--project projectThe current github project. This is also optional.--nocdnTicking this will use relative paths for the output images. Defaults to False.--htmlizeTicking this will output amd.htmlfile so you can preview what the output looks like. Defaults to False.--valignTicking this will use thevaligntrick (detailed below) instead. See the caveats section for tradeoffs.--rerenderTicking this will force a recompilation of all formulas even if they are already cached.--bustcacheTicking this will ensure that Github renews its image cache. Github may sometimes take up to an hour for changed images to reappear. This is usually not necessary unless you've made stylistic changes.--add-git-hookTicking this will generate a post-commit hook for git that runs readme2tex with the rest of the specified arguments after eachgit commit.--pngtrickTicking this will generatepngfiles instead ofsvgsfor the formulas.
My usual workflow is to create a secondary branch just for the compiled svgs. You can accomplish this via
python -m readme2tex --branch svgs --output README.md
However, be careful with this command, since it will switch over to the svgs branch without any input from you.
If you're on a private repository or you want to, for whatever reason, use relative paths to resolve your images, you can do so by using the combination
python -m readme2tex --branch master --nocdn --pngtrick ...
which will output pngs relative to your README.md.
Due to security considerations, Github will not resolve svgs relatively, which means that private repositories will
be locked out of the usual svg workflow. Using the --branch master --nocdn --pngtrick combination will get around
this restriction.
If your Tikz drawings don't show up, there's a good chance that you either don't have Ghostscript installed or
dvisvgm isn't picking it up for whatever reason. This is most likely to happen on some installations of TexLive
on OSX.
Check to see if ps is included in the list when you run
# dvisvgm -l
bgcolor background color special
color complete support of color specials
dvisvgm special set for embedding raw SVG snippets
em line drawing statements of the emTeX special set
html hyperref specials
pdf pdfTeX font map specials
ps dvips PostScript specials <<<
tpic TPIC specialsIf not, try installing it (either apt-get, yum, or brew). Furthermore, if you are on OSX, make sure to add the
following to your ~/.bash_profile
export LIBGS=/usr/local/lib/libgs.dylibwhere /usr/local/lib/libgs.dylib is the location where libgs.dylib is installed.
Make sure that if you have a <p>...</p> tag somewhere, you leave at least one blank line after the closing tag.
chmod +x .git/hooks/post-commitTry running readme2tex with
python -m readme2tex ... --username GITHUB_USERNAME --project PROJECT_NAMEUnfortunately, this script still has a few kinks and bugs that I need to iron out. In the mean time, if the pypi releases
aren't working for you, you should switch over to the development version to see if the bugs have been squashed:
git clone https://github.com/leegao/readme2tex
cd readme2tex
python setup.py developBy prepending every inline formula with an anchor. During post-processing, we can isolate the anchor, which is fixed at the baseline, and crop it out. It's super clowny, but it does the job.
Github does not allow you to pass in custom style attributes to your images. While this is useful for security purposes,
it makes it incredibly difficult to ensure that images will align correctly to the text. readme2tex circumvents this
using one of two tricks:
- In Chrome, the attribute
valign=offsetworks forimgtags as well. This allows us to shift the image directly. Unfortunately, this is not supported within any of the other major browsers, therefore this mode is not enabled by default. - In every (reasonably modern) browser, the
align=middleattribute will vertically center an image. However, the definition of the vertical "center" is different. In particular, for Chrome, Firefox, (and probably Safari), that center is the exact middle of the image. For IE and Edge however, the center is about 5 pixels (the height of a lower-case character) above the exact center. Since this looks great for non-IE browsers, and reasonably good on Edge, this is the default rendering method. The trick here is to pad either the top or the bottom of the image with extra spaces until the baseline of the formula is at the center. For most formulas, this works great. However, if you have a tall formula, like
, you'll notice that there might be a lot
of slack vertical spacing between these lines. If this is a deal-breaker for you, you can always try the --valign Truemode. For most inline formulas, this is usually a non-issue.
Make sure that you have the tikz and the xcolor packages installed locally.
python -m readme2tex --usepackage "tikz" --usepackage "xcolor" --output README.md --branch svgs
and of course
python -m readme2tex --usepackage "tikz" --usepackage "xcolor" --output README.md --branch svgs --add-git-hook
For the png relative mode, use
python -m readme2tex --usepackage "tikz" --usepackage "xcolor" --output README.md --branch master --nocdn --pngtrick
![\begin{tikzpicture}[scale=0.25, line join=bevel]
% \a and \b are two macros defining characteristic
% dimensions of the Penrose triangle.
\pgfmathsetmacro{\a}{2.5}
\pgfmathsetmacro{\b}{0.9}
\tikzset{%
apply style/.code = {\tikzset{#1}},
triangle_edges/.style = {thick,draw=black}
}
\foreach \theta/\facestyle in {%
0/{triangle_edges, fill = gray!50},
120/{triangle_edges, fill = gray!25},
240/{triangle_edges, fill = gray!90}%
}{
\begin{scope}[rotate=\theta]
\draw[apply style/.expand once=\facestyle]
({-sqrt(3)/2*\a},{-0.5*\a}) --
++(-\b,0) --
({0.5*\b},{\a+3*sqrt(3)/2*\b}) -- % higher point
({sqrt(3)/2*\a+2.5*\b},{-.5*\a-sqrt(3)/2*\b}) -- % rightmost point
++({-.5*\b},-{sqrt(3)/2*\b}) -- % lower point
({0.5*\b},{\a+sqrt(3)/2*\b}) --
cycle;
\end{scope}
}
\end{tikzpicture}](svgs/48ab6ba0b4263d6ecddedfd213f66ff5.png?invert_in_darkmode)
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