matplotlib · timhoffm · Apr 7, 2022 · Apr 7, 2022
diff --git a/doc/api/next_api_changes/deprecations/22797-OG.rst b/doc/api/next_api_changes/deprecations/22797-OG.rst
@@ -0,0 +1,12 @@
+Deprecation of helper functions in backends
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following functions are considered private and deprecated. Vendor the code
+of the similarly named private functions if you rely on these functions.
+
+* ``backend_pdf.fill``
+* ``backend_ps.quote_ps_string``
+* ``backend_svg.escape_attrib``
+* ``backend_svg.escape_cdata``
+* ``backend_svg.escape_comment``
+* ``backend_svg.short_float_fmt``
diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -93,7 +93,12 @@
 # * draw_quad_mesh
 
 
+@_api.deprecated("3.6", alternative="Vendor the code")
 def fill(strings, linelen=75):
+    return _fill(strings, linelen=linelen)
+
+
+def _fill(strings, linelen=75):
     """
     Make one string from sequence of strings, with whitespace in between.
 
@@ -292,15 +297,15 @@ def pdfRepr(obj):
     # anything, so the caller must ensure that PDF names are
     # represented as Name objects.
     elif isinstance(obj, dict):
-        return fill([
+        return _fill([
             b"<<",
             *[Name(k).pdfRepr() + b" " + pdfRepr(v) for k, v in obj.items()],
             b">>",
         ])
 
     # Lists.
     elif isinstance(obj, (list, tuple)):
-        return fill([b"[", *[pdfRepr(val) for val in obj], b"]"])
+        return _fill([b"[", *[pdfRepr(val) for val in obj], b"]"])
 
     # The null keyword.
     elif obj is None:
@@ -312,7 +317,7 @@ def pdfRepr(obj):
 
     # A bounding box
     elif isinstance(obj, BboxBase):
-        return fill([pdfRepr(val) for val in obj.bounds])
+        return _fill([pdfRepr(val) for val in obj.bounds])
 
     else:
         raise TypeError("Don't know a PDF representation for {} objects"
@@ -833,7 +838,7 @@ def write(self, data):
             self.currentstream.write(data)
 
     def output(self, *data):
-        self.write(fill([pdfRepr(x) for x in data]))
+        self.write(_fill([pdfRepr(x) for x in data]))
         self.write(b'\n')
 
     def beginStream(self, id, len, extra=None, png=None):

diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
@@ -89,7 +89,12 @@ def _nums_to_str(*args):
     return " ".join(f"{arg:1.3f}".rstrip("0").rstrip(".") for arg in args)
 
 
+@_api.deprecated("3.6", alternative="Vendor the code")
 def quote_ps_string(s):
+    return _quote_ps_string(s)
+
+
+def _quote_ps_string(s):
     """
     Quote dangerous characters of S for use in a PostScript string constant.
     """
@@ -738,7 +743,7 @@ def draw_gouraud_triangles(self, gc, points, colors, trans):
         streamarr['flags'] = 0
         streamarr['points'] = (flat_points - points_min) * factor
         streamarr['colors'] = flat_colors[:, :3] * 255.0
-        stream = quote_ps_string(streamarr.tobytes())
+        stream = _quote_ps_string(streamarr.tobytes())
 
         self._pswriter.write(f"""\
 gsave