Merge pull request matplotlib#19501 from QuLogic/usetex-xcolor

FIX: text position with usetex and xcolor

Author: tacaswell

lib/matplotlib/dviread.py

@@ -313,18 +313,26 @@ def _read(self):
         #   xxx comment
         #   down
         #   push
-        #     down, down
+        #     down
+        #     <push, push, xxx, right, xxx, pop, pop>  # if using xcolor
+        #     down
         #     push
         #       down (possibly multiple)
         #       push  <=  here, v is the baseline position.
         #         etc.
         # (dviasm is useful to explore this structure.)
+        # Thus, we use the vertical position at the first time the stack depth
+        # reaches 3, while at least three "downs" have been executed, as the
+        # baseline (the "down" count is necessary to handle xcolor).
+        downs = 0
         self._baseline_v = None
         while True:
             byte = self.file.read(1)[0]
             self._dtable[byte](self, byte)
+            downs += self._dtable[byte].__name__ == "_down"
             if (self._baseline_v is None
-                    and len(getattr(self, "stack", [])) == 3):
+                    and len(getattr(self, "stack", [])) == 3
+                    and downs >= 4):
                 self._baseline_v = self.v
             if byte == 140:                         # end of page
                 return True

lib/matplotlib/testing/__init__.py

@@ -75,3 +75,7 @@ def check_for_pgf(texsystem):
         except (OSError, subprocess.CalledProcessError):
             return False
         return True
+
+
+def _has_tex_package(package):
+    return bool(mpl.dviread.find_tex_file(f"{package}.sty"))

lib/matplotlib/tests/test_backend_pgf.py

@@ -2,14 +2,13 @@
 from io import BytesIO
 import os
 import shutil
-import subprocess
 
 import numpy as np
 import pytest
 
 import matplotlib as mpl
 import matplotlib.pyplot as plt
-from matplotlib.testing import check_for_pgf
+from matplotlib.testing import _has_tex_package, check_for_pgf
 from matplotlib.testing.compare import compare_images, ImageComparisonFailure
 from matplotlib.backends.backend_pgf import PdfPages, common_texification
 from matplotlib.testing.decorators import (_image_directories,
@@ -29,10 +28,6 @@
     reason="This test needs a ghostscript installation")
 
 
-def _has_tex_package(package):
-    return bool(mpl.dviread.find_tex_file(f"{package}.sty"))
-
-
 def compare_figure(fname, savefig_kwargs={}, tol=0):
     actual = os.path.join(result_dir, fname)
     plt.savefig(actual, **savefig_kwargs)

lib/matplotlib/tests/test_usetex.py

@@ -2,6 +2,7 @@
 import pytest
 
 import matplotlib as mpl
+from matplotlib.testing import _has_tex_package
 from matplotlib.testing.decorators import check_figures_equal, image_comparison
 import matplotlib.pyplot as plt
 
@@ -80,6 +81,23 @@ def test_minus_no_descent(fontsize):
     assert len({*heights.values()}) == 1
 
 
+@pytest.mark.skipif(not _has_tex_package('xcolor'),
+                    reason='xcolor is not available')
+def test_usetex_xcolor():
+    mpl.rcParams['text.usetex'] = True
+
+    fig = plt.figure()
+    text = fig.text(0.5, 0.5, "Some text 0123456789")
+    fig.canvas.draw()
+
+    mpl.rcParams['text.latex.preamble'] = r'\usepackage[dvipsnames]{xcolor}'
+    fig = plt.figure()
+    text2 = fig.text(0.5, 0.5, "Some text 0123456789")
+    fig.canvas.draw()
+    np.testing.assert_array_equal(text2.get_window_extent(),
+                                  text.get_window_extent())
+
+
 def test_textcomp_full():
     plt.rcParams["text.latex.preamble"] = r"\usepackage[full]{textcomp}"
     fig = plt.figure()