Add safe_pdf and save_svg helpers

gunshotmatch_reports/utils.py

@@ -27,16 +27,19 @@
 #
 
 # stdlib
-from io import BytesIO
+from io import BytesIO, StringIO
 from typing import List, Tuple, TypeVar
 
 # 3rd party
-from matplotlib import pyplot as plt  # type: ignore[import]
+import matplotlib  # type: ignore[import]
+from domdf_python_tools.paths import PathPlus
+from domdf_python_tools.typing import PathLike
+from matplotlib import pyplot as plt
 from matplotlib.figure import Figure  # type: ignore[import]
 from reportlab.graphics.shapes import Drawing  # type: ignore[import]
 from svglib.svglib import svg2rlg  # type: ignore[import]
 
-__all__ = ["extend_list", "figure_to_drawing", "scale"]
+__all__ = ["extend_list", "figure_to_drawing", "scale", "save_pdf", "save_svg"]
 
 
 def scale(drawing: Drawing, scale: float) -> Drawing:
@@ -89,3 +92,39 @@ def extend_list(l: List[_T], fillvalue: _T, length: int) -> List[_T]:
 	assert len(l) == length
 
 	return l
+
+
+def save_pdf(fig: Figure, filename: PathLike) -> None:
+	"""
+	Save a PDF without a creation date.
+
+	:param fig:
+	:param filename:
+
+	.. versionadded:: 0.6.0
+	"""
+
+	fig.savefig(filename, format="pdf", metadata={"CreationDate": None})
+
+
+def save_svg(fig: Figure, filename: PathLike) -> None:
+	"""
+	Save an SVG with fixed hashsalt and without a creation date.
+
+	:param fig:
+	:param filename:
+
+	.. versionadded:: 0.6.0
+	"""
+
+	filename_p = PathPlus(filename)
+
+	current_hashsalt = matplotlib.rcParams.get("svg.hashsalt")
+
+	try:
+		matplotlib.rcParams["svg.hashsalt"] = filename_p.name
+		s = StringIO()
+		fig.savefig(s, format="svg", metadata={"Date": None})
+		filename_p.write_clean(s.getvalue())
+	finally:
+		matplotlib.rcParams["svg.hashsalt"] = current_hashsalt