Revived utils/tex_file_writing.py

utils/tex_file_writing.py

@@ -0,0 +1,81 @@
+import os
+from constants import TEX_DIR
+from constants import TEX_TEXT_TO_REPLACE
+
+
+def tex_hash(expression, template_tex_file):
+    return str(hash(expression + template_tex_file))
+
+
+def tex_to_svg_file(expression, template_tex_file):
+    tex_file = generate_tex_file(expression, template_tex_file)
+    dvi_file = tex_to_dvi(tex_file)
+    return dvi_to_svg(dvi_file)
+
+
+def generate_tex_file(expression, template_tex_file):
+    result = os.path.join(
+        TEX_DIR,
+        tex_hash(expression, template_tex_file)
+    ) + ".tex"
+    if not os.path.exists(result):
+        print("Writing \"%s\" to %s" % (
+            "".join(expression), result
+        ))
+        with open(template_tex_file, "r") as infile:
+            body = infile.read()
+            body = body.replace(TEX_TEXT_TO_REPLACE, expression)
+        with open(result, "w") as outfile:
+            outfile.write(body)
+    return result
+
+
+def get_null():
+    if os.name == "nt":
+        return "NUL"
+    return "/dev/null"
+
+
+def tex_to_dvi(tex_file):
+    result = tex_file.replace(".tex", ".dvi")
+    if not os.path.exists(result):
+        commands = [
+            "latex",
+            "-interaction=batchmode",
+            "-halt-on-error",
+            "-output-directory=" + TEX_DIR,
+            tex_file,
+            ">",
+            get_null()
+        ]
+        exit_code = os.system(" ".join(commands))
+        if exit_code != 0:
+            log_file = tex_file.replace(".tex", ".log")
+            raise Exception(
+                "Latex error converting to dvi. "
+                "See log output above or the log file: %s" % log_file)
+    return result
+
+
+def dvi_to_svg(dvi_file, regen_if_exists=False):
+    """
+    Converts a dvi, which potentially has multiple slides, into a
+    directory full of enumerated pngs corresponding with these slides.
+    Returns a list of PIL Image objects for these images sorted as they
+    where in the dvi
+    """
+    result = dvi_file.replace(".dvi", ".svg")
+    if not os.path.exists(result):
+        commands = [
+            "dvisvgm",
+            dvi_file,
+            "-n",
+            "-v",
+            "0",
+            "-o",
+            result,
+            ">",
+            get_null()
+        ]
+        os.system(" ".join(commands))
+    return result