Use pipes to communicate with mathjax; add asciimath support (#2)

* change svg I/O from shell args to pipe;
add asciimath support

* update README

README.md

@@ -12,4 +12,6 @@ $ manimgl-mathjax install
 ⚠ Currently you must use the latest version of ManimGL (i.e. clone from GitHub and install)
 
 ## Usage
-Just use `JTex` instead of [`MTex`](https://github.com/3b1b/manim/pull/1725#issue-1121866424)
+Just use `JTex` instead of [`MTex`](https://github.com/3b1b/manim/pull/1725#issue-1121866424)
+
+Use `AM` to write math in [asciimath](http://asciimath.org/) notation, [see also](https://zmx0142857.gitee.io/note/#math).

manimgl_mathjax/__init__.py

@@ -2,4 +2,4 @@
 
 __version__ = pkg_resources.get_distribution("manimgl_mathjax").version
 
-from .mathjax import JTex
+from .mathjax import JTex, AM

manimgl_mathjax/index.js

@@ -1,5 +1,40 @@
-const fs = require('fs')
+/**
+ * This file reads asciimath string from stdin and output svg formula to
+ * stdout.  On linux you can end the input with ctrl-d; unfortunately on
+ * windows this is not possible, so you may use ctrl-c to interrupt the
+ * input.
+ *
+ * Another option is to redirect from file:
+ *   $ node index.js < input.txt
+ * On windows, quote is needed:
+ *   $ "node" index.js < input.txt
+ */
+
+const { am2tex } = require('asciimath-js')
 const tex2svg = require('./tex2svg.js')
+const { stdin, stdout } = process
+const buf = []
+
+stdin.setEncoding('utf8')
+
+stdin.on('readable', () => {
+  let data
+  while ((data = stdin.read()) !== null) {
+    buf.push(data.trim())
+  }
+})
+
+const convert = process.argv[2] === '--am'
+  ? (input) => tex2svg(am2tex(input))
+  : tex2svg
+
+function onEnd () {
+  const input = buf.join('\n')
+  convert(input).then(svg => {
+    console.log(svg)
+    process.exit()
+  })
+}
 
-let { argv } = process
-tex2svg(argv[3]).then(svg => fs.writeFileSync(argv[2], svg))
+stdin.on('end', onEnd)
+process.on('SIGINT', onEnd)

manimgl_mathjax/mathjax.py

@@ -3,6 +3,7 @@
 import sys
 import inspect
 import importlib
+import subprocess
 from manimlib.logger import log
 from manimlib.utils.directories import get_tex_dir
 from manimlib.mobject.svg.mtex_mobject import MTex
@@ -15,33 +16,31 @@ def get_mathjax_dir():
     return os.path.abspath(os.path.join(directory, "index.js"))
 
 
-def tex_content_to_svg_file_using_mathjax(tex_content):
+def tex_content_to_svg_file_using_mathjax(tex_content, *args):
     svg_file = os.path.join(
         get_tex_dir(), tex_hash(tex_content) + ".svg"
     )
     if not os.path.exists(svg_file):
-        tex_content_to_svg_using_mathjax(tex_content, svg_file)
-    return svg_file
-
+        # create pipe
+        process = subprocess.Popen(
+            ["node", get_mathjax_dir(), *args],
+            stdout=subprocess.PIPE,
+            stdin=subprocess.PIPE
+        )
+        process.stdin.write(bytes(tex_content, "utf-8"))
+        stdout, stderr = process.communicate()
 
-def tex_content_to_svg_using_mathjax(tex_file_content, svg_file):
-    commands = [
-        "node",
-        f"\"{get_mathjax_dir()}\"",
-        f"\"{svg_file}\"",
-        f"\"{tex_file_content}\"",
-        ">",
-        os.devnull
-    ]
-    exit_code = os.system(" ".join(commands))
-    with open(svg_file, "r", encoding="utf-8") as file:
-        error_match_obj = re.search(r"(?<=data\-mjx\-error\=\")(.*?)(?=\")", file.read())
-    if exit_code != 0 or error_match_obj is not None:
-        log.error("LaTeX Error!  Not a worry, it happens to the best of us.")
+        # capture LaTeX error
+        svg_str = str(stdout, "utf-8")
+        error_match_obj = re.search(r"(?<=data\-mjx\-error\=\")(.*?)(?=\")", svg_str)
         if error_match_obj is not None:
+            log.error("LaTeX Error!  Not a worry, it happens to the best of us.")
             log.debug(f"The error could be: `{error_match_obj.group()}`")
-        os.remove(svg_file)
-        sys.exit(2)
+            sys.exit(2)
+
+        # save svg file
+        with open(svg_file, "wb") as out:
+            out.write(stdout)
     return svg_file
 
 
@@ -73,9 +72,17 @@ def hash_seed(self):
     def get_tex_file_body(self, tex_string):
         if not self.use_mathjax:
             return super().get_tex_file_body(tex_string)
-        return tex_string.replace("\"", "\\\"").replace("\n", " ")
+        return tex_string
 
     def tex_to_svg_file_path(self, tex_file_content):
         if not self.use_mathjax:
             return super().tex_to_svg_file_path(tex_file_content)
         return tex_content_to_svg_file_using_mathjax(tex_file_content)
+
+
+class AM(JTex):
+    def get_tex_file_body(self, am_string):
+        return am_string
+
+    def get_file_path(self):
+        return tex_content_to_svg_file_using_mathjax(self.tex_string, "--am")

manimgl_mathjax/package.json

@@ -1,5 +1,6 @@
 {
   "dependencies": {
+    "asciimath-js": "^1.0.1",
     "mathjax-full": "^3.2.0"
   },
   "name": "manim-mathjax",