Deprecate backend_ps.convert_psfrags.

It is tightly coupled to Matplotlib's choice of using psfrags to
implement ps+usetex (e.g., through the renderer.psfrag attribute) and
thus unlikely to be useful elsewhere (unlike the distiller functions,
which mplcairo reuses).  Making it private also allows getting rid of
now unused args (font_preamble and custom_preamble), supporting only
pathlib.Path args, and may perhaps later allow getting rid of paper
orientation handling too.

Author: anntzer

doc/api/next_api_changes/deprecations/22422-AL.rst

@@ -0,0 +1,3 @@
+``backend_ps.convert_psfrags``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+... is deprecated.

lib/matplotlib/backends/backend_ps.py

@@ -1045,8 +1045,8 @@ def _print_figure_tex(
 
         # write to a temp file, we'll move it to outfile when done
         with TemporaryDirectory() as tmpdir:
-            tmpfile = os.path.join(tmpdir, "tmp.ps")
-            pathlib.Path(tmpfile).write_text(
+            tmppath = pathlib.Path(tmpdir, "tmp.ps")
+            tmppath.write_text(
                 f"""\
 %!PS-Adobe-3.0 EPSF-3.0
 {dsc_comments}
@@ -1082,27 +1082,21 @@ def _print_figure_tex(
                     papertype = _get_papertype(width, height)
                 paper_width, paper_height = papersize[papertype]
 
-            texmanager = ps_renderer.get_texmanager()
-            font_preamble = texmanager.get_font_preamble()
-            custom_preamble = texmanager.get_custom_preamble()
-
-            psfrag_rotated = convert_psfrags(tmpfile, ps_renderer.psfrag,
-                                             font_preamble,
-                                             custom_preamble, paper_width,
-                                             paper_height,
-                                             orientation.name)
+            psfrag_rotated = _convert_psfrags(
+                tmppath, ps_renderer.psfrag, paper_width, paper_height,
+                orientation.name)
 
             if (mpl.rcParams['ps.usedistiller'] == 'ghostscript'
                     or mpl.rcParams['text.usetex']):
                 _try_distill(gs_distill,
-                             tmpfile, is_eps, ptype=papertype, bbox=bbox,
+                             tmppath, is_eps, ptype=papertype, bbox=bbox,
                              rotated=psfrag_rotated)
             elif mpl.rcParams['ps.usedistiller'] == 'xpdf':
                 _try_distill(xpdf_distill,
-                             tmpfile, is_eps, ptype=papertype, bbox=bbox,
+                             tmppath, is_eps, ptype=papertype, bbox=bbox,
                              rotated=psfrag_rotated)
 
-            _move_path_to_path_or_stream(tmpfile, outfile)
+            _move_path_to_path_or_stream(tmppath, outfile)
 
     print_ps = functools.partialmethod(_print_ps, "ps")
     print_eps = functools.partialmethod(_print_ps, "eps")
@@ -1112,8 +1106,14 @@ def draw(self):
         return super().draw()
 
 
+@_api.deprecated("3.6")
 def convert_psfrags(tmpfile, psfrags, font_preamble, custom_preamble,
                     paper_width, paper_height, orientation):
+    return _convert_psfrags(
+        pathlib.Path(tmpfile), psfrags, paper_width, paper_height, orientation)
+
+
+def _convert_psfrags(tmppath, psfrags, paper_width, paper_height, orientation):
     """
     When we want to use the LaTeX backend with postscript, we write PSFrag tags
     to a temporary postscript file, each one marking a position for LaTeX to
@@ -1140,15 +1140,15 @@ def convert_psfrags(tmpfile, psfrags, font_preamble, custom_preamble,
             % {
                 "psfrags": "\n".join(psfrags),
                 "angle": 90 if orientation == 'landscape' else 0,
-                "epsfile": pathlib.Path(tmpfile).resolve().as_posix(),
+                "epsfile": tmppath.resolve().as_posix(),
             },
             fontsize=10)  # tex's default fontsize.
 
     with TemporaryDirectory() as tmpdir:
         psfile = os.path.join(tmpdir, "tmp.ps")
         cbook._check_and_log_subprocess(
             ['dvips', '-q', '-R0', '-o', psfile, dvifile], _log)
-        shutil.move(psfile, tmpfile)
+        shutil.move(psfile, tmppath)
 
     # check if the dvips created a ps in landscape paper.  Somehow,
     # above latex+dvips results in a ps file in a landscape mode for a
@@ -1157,14 +1157,14 @@ def convert_psfrags(tmpfile, psfrags, font_preamble, custom_preamble,
     # the generated ps file is in landscape and return this
     # information. The return value is used in pstoeps step to recover
     # the correct bounding box. 2010-06-05 JJL
-    with open(tmpfile) as fh:
+    with open(tmppath) as fh:
         psfrag_rotated = "Landscape" in fh.read(1000)
     return psfrag_rotated
 
 
-def _try_distill(func, *args, **kwargs):
+def _try_distill(func, tmppath, *args, **kwargs):
     try:
-        func(*args, **kwargs)
+        func(str(tmppath), *args, **kwargs)
     except mpl.ExecutableNotFoundError as exc:
         _log.warning("%s.  Distillation step skipped.", exc)