Merge pull request matplotlib#20446 from anntzer/psp

Make used tex packages consistent between ps and other backends.

Author: QuLogic

lib/matplotlib/backends/backend_ps.py

@@ -1117,8 +1117,13 @@ def convert_psfrags(tmpfile, psfrags, font_preamble, custom_preamble,
     with mpl.rc_context({
             "text.latex.preamble":
             mpl.rcParams["text.latex.preamble"] +
-            r"\usepackage{psfrag,color}""\n"
-            r"\usepackage[dvips]{graphicx}""\n"
+            # Only load these packages if they have not already been loaded, in
+            # order not to clash with custom packages.
+            r"\makeatletter"
+            r"\@ifpackageloaded{color}{}{\usepackage{color}}"
+            r"\@ifpackageloaded{graphicx}{}{\usepackage{graphicx}}"
+            r"\@ifpackageloaded{psfrag}{}{\usepackage{psfrag}}"
+            r"\makeatother"
             r"\geometry{papersize={%(width)sin,%(height)sin},margin=0in}"
             % {"width": paper_width, "height": paper_height}
     }):

lib/matplotlib/mpl-data/matplotlibrc

@@ -319,10 +319,10 @@
                         # statements.
                         # Note that it has to be put on a single line, which may
                         # become quite long.
-                        # The following packages are always loaded with usetex, so
-                        # beware of package collisions: color, geometry, graphicx,
-                        # type1cm, textcomp.
-                        # Adobe Postscript (PSSNFS) font packages may also be
+                        # The following packages are always loaded with usetex,
+                        # so beware of package collisions:
+                        #   geometry, inputenc, type1cm.
+                        # PostScript (PSNFSS) font packages may also be
                         # loaded, depending on your font settings.
 
 ## The following settings allow you to select the fonts in math mode.

lib/matplotlib/tests/test_backend_ps.py

@@ -155,6 +155,17 @@ def test_partial_usetex(caplog):
                                   for record in caplog.records)
 
 
+@needs_usetex
+def test_usetex_preamble(caplog):
+    mpl.rcParams.update({
+        "text.usetex": True,
+        # Check that these don't conflict with the packages loaded by default.
+        "text.latex.preamble": r"\usepackage{color,graphicx,textcomp}",
+    })
+    plt.figtext(.5, .5, "foo")
+    plt.savefig(io.BytesIO(), format="ps")
+
+
 @image_comparison(["useafm.eps"])
 def test_useafm():
     mpl.rcParams["ps.useafm"] = True