enh: store basic software info in png metadata

yt/funcs.py

@@ -24,6 +24,7 @@
 from more_itertools import always_iterable, collapse, first
 
 from yt._maintenance.deprecation import issue_deprecation_warning
+from yt._version import __version__ as yt_version
 from yt.config import ytcfg
 from yt.units import YTArray, YTQuantity
 from yt.utilities.exceptions import YTFieldNotFound, YTInvalidWidthError
@@ -566,7 +567,7 @@ def get_version_stack():
     import matplotlib
 
     version_info = {}
-    version_info["yt"] = get_yt_version()
+    version_info["yt"] = yt_version
     version_info["numpy"] = np.version.version
     version_info["matplotlib"] = matplotlib.__version__
     return version_info
@@ -1447,3 +1448,22 @@ def validate_moment(moment, weight_field):
             "Weighted projections can only be made of averages "
             "(moment = 1) or standard deviations (moment = 2)!"
         )
+
+
+def setdefault_mpl_metadata(mpl_kwargs, name):
+    """
+    Set a default Software metadata entry for use with Matplotlib outputs.
+    """
+    _, ext = os.path.splitext(name.lower())
+    if ext in (".eps", ".ps", ".svg", ".pdf"):
+        key = "Creator"
+    elif ext == ".png":
+        key = "Software"
+    else:
+        return
+    default_software = (
+        "Matplotlib version{matplotlib}, https://matplotlib.org|NumPy-{numpy}|yt-{yt}"
+    )
+    metadata = {}
+    metadata.setdefault(key, default_software.format(**get_version_stack()))
+    mpl_kwargs.setdefault("metadata", metadata)

yt/utilities/png_writer.py

@@ -1,10 +1,18 @@
 from io import BytesIO
 
+import PIL
 from PIL import Image
+from PIL.PngImagePlugin import PngInfo
+
+from .._version import __version__ as yt_version
 
 
 def call_png_write_png(buffer, fileobj, dpi):
-    Image.fromarray(buffer).save(fileobj, dpi=(dpi, dpi), format="png")
+    metadata = PngInfo()
+    metadata.add_text("Software", f"{PIL.__name__}-{PIL.__version__}|yt-{yt_version}")
+    Image.fromarray(buffer).save(
+        fileobj, dpi=(dpi, dpi), format="png", pnginfo=metadata
+    )
 
 
 def write_png(buffer, filename, dpi=100):

yt/visualization/base_plot_types.py

@@ -8,7 +8,13 @@
 import numpy as np
 from matplotlib.ticker import LogFormatterMathtext
 
-from yt.funcs import get_interactivity, is_sequence, matplotlib_style_context, mylog
+from yt.funcs import (
+    get_interactivity,
+    is_sequence,
+    matplotlib_style_context,
+    mylog,
+    setdefault_mpl_metadata,
+)
 from yt.visualization._handlers import ColorbarHandler, NormHandler
 
 from ._commons import (
@@ -162,6 +168,7 @@ def save(self, name, mpl_kwargs=None, canvas=None):
             mpl_kwargs = {}
 
         name = validate_image_name(name)
+        setdefault_mpl_metadata(mpl_kwargs, name)
 
         try:
             canvas = get_canvas(self.figure, name)