matplotlib · QuLogic · Mar 27, 2026 · Mar 24, 2026 · Mar 20, 2026 · Mar 26, 2026
diff --git a/.github/workflows/cygwin.yml b/.github/workflows/cygwin.yml
@@ -182,7 +182,7 @@ jobs:
           export PATH="/usr/local/bin:$PATH"
           python -m pip install --no-build-isolation 'contourpy>=1.0.1'
           python -m pip install --upgrade cycler fonttools \
-              packaging pyparsing python-dateutil setuptools-scm \
+              packaging pyparsing python-dateutil 'setuptools-scm<10' \
               -r requirements_test.txt sphinx ipython
           python -m pip install --upgrade pycairo 'cairocffi>=0.8' PyGObject &&
              python -c 'import gi; gi.require_version("Gtk", "3.0"); from gi.repository import Gtk' &&

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
@@ -256,7 +256,7 @@ jobs:
           # Preinstall build requirements to enable no-build-isolation builds.
           python -m pip install --upgrade $PRE \
             'contourpy>=1.0.1' cycler fonttools kiwisolver importlib_resources \
-            packaging pillow 'pyparsing!=3.1.0' python-dateutil setuptools-scm \
+            packaging pillow 'pyparsing!=3.1.0' python-dateutil 'setuptools-scm<10' \
             'meson-python>=0.13.1' 'pybind11>=2.13.2' \
             -r requirements/testing/all.txt \
             ${{ matrix.extra-requirements }}

diff --git a/lib/matplotlib/_afm.py b/lib/matplotlib/_afm.py
@@ -478,10 +478,18 @@ def get_angle(self) -> float:
         """Return the fontangle as float."""
         return self._header['ItalicAngle']
 
+    def get_ascender(self) -> float:
+        """Return the ascent as float."""
+        return self._header['Ascender']
+
     def get_capheight(self) -> float:
         """Return the cap height as float."""
         return self._header['CapHeight']
 
+    def get_descender(self) -> float:
+        """Return the descent as float."""
+        return self._header['Descender']
+
     def get_xheight(self) -> float:
         """Return the xheight as float."""
         return self._header['XHeight']

diff --git a/lib/matplotlib/backends/_backend_pdf_ps.py b/lib/matplotlib/backends/_backend_pdf_ps.py
@@ -348,6 +348,32 @@ def get_canvas_width_height(self):
         # docstring inherited
         return self.width * 72.0, self.height * 72.0
 
+    def _get_font_height_metrics(self, prop):
+        """
+        Return the ascent, descent, and line gap for font described by *prop*.
+
+        TODO: This is a temporary method until we design a proper API for the backends.
+
+        Parameters
+        ----------
+        prop : `.font_manager.FontProperties`
+            The properties describing the font to measure.
+
+        Returns
+        -------
+        ascent, descent, line_gap : float or None
+            The ascent, descent and line gap of the determined font, or None to fall
+            back to normal measurements.
+        """
+        if not mpl.rcParams[self._use_afm_rc_name]:
+            return None, None, None
+        font = self._get_font_afm(prop)
+        scale = prop.get_size_in_points() / 1000
+        a = font.get_ascender() * scale
+        d = -font.get_descender() * scale
+        g = (a + d) * 0.2  # Preserve previous line spacing of 1.2.
+        return a, d, g
+
     def get_text_width_height_descent(self, s, prop, ismath):
         # docstring inherited
         if ismath == "TeX":

diff --git a/lib/matplotlib/tests/baseline_images/test_backend_pdf/pdf_use14corefonts.pdf b/lib/matplotlib/tests/baseline_images/test_backend_pdf/pdf_use14corefonts.pdf
diff --git a/lib/matplotlib/tests/test_bbox_tight.py b/lib/matplotlib/tests/test_bbox_tight.py
@@ -47,7 +47,7 @@ def test_bbox_inches_tight(text_placeholders):
 
 @image_comparison(['bbox_inches_tight_suptile_legend'],
                   savefig_kwarg={'bbox_inches': 'tight'},
-                  tol=0 if platform.machine() == 'x86_64' else 0.022)
+                  tol=0 if platform.machine() == 'x86_64' else 0.024)
 def test_bbox_inches_tight_suptile_legend():
     plt.plot(np.arange(10), label='a straight line')
     plt.legend(bbox_to_anchor=(0.9, 1), loc='upper left')

diff --git a/lib/matplotlib/tests/test_mathtext.py b/lib/matplotlib/tests/test_mathtext.py
@@ -224,8 +224,11 @@ def baseline_images(request, fontset, index, text):
 @pytest.mark.parametrize(
     'fontset', ['cm', 'stix', 'stixsans', 'dejavusans', 'dejavuserif'])
 @pytest.mark.parametrize('baseline_images', ['mathtext'], indirect=True)
-@image_comparison(baseline_images=None, style='mpl20',
-                  tol=0.011 if platform.machine() in ('ppc64le', 's390x') else 0)
+@image_comparison(
+    baseline_images=None, style='mpl20',
+    tol=(0.013
+         if platform.machine() in ('ppc64le', 's390x') or platform.system() == 'Windows'
+         else 0))
 def test_mathtext_rendering(baseline_images, fontset, index, text):
     mpl.rcParams['mathtext.fontset'] = fontset
     fig = plt.figure(figsize=(5.25, 0.75))

diff --git a/lib/matplotlib/tests/test_patheffects.py b/lib/matplotlib/tests/test_patheffects.py
@@ -120,7 +120,7 @@ def test_SimplePatchShadow_offset():
     assert pe._offset == (4, 5)
 
 
-@image_comparison(['collection'], tol=0.03, style='mpl20')
+@image_comparison(['collection'], tol=0.032, style='mpl20')
 def test_collection():
     x, y = np.meshgrid(np.linspace(0, 10, 150), np.linspace(-5, 5, 100))
     data = np.sin(x) + np.cos(y)

diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
@@ -437,22 +437,29 @@ def _get_layout(self, renderer):
         dpi = self.get_figure(root=True).dpi
         # Determine full vertical extent of font, including ascenders and descenders:
         if not self.get_usetex():
-            font = get_font(fontManager._find_fonts_by_props(self._fontproperties))
-            possible_metrics = [
-                ('OS/2', 'sTypoLineGap', 'sTypoAscender', 'sTypoDescender'),
-                ('hhea', 'lineGap', 'ascent', 'descent')
-            ]
-            for table_name, linegap_key, ascent_key, descent_key in possible_metrics:
-                table = font.get_sfnt_table(table_name)
-                if table is None:
-                    continue
-                # Rescale to font size/DPI if the metrics were available.
-                fontsize = self._fontproperties.get_size_in_points()
-                units_per_em = font.get_sfnt_table('head')['unitsPerEm']
-                line_gap = table[linegap_key] / units_per_em * fontsize * dpi / 72
-                min_ascent = table[ascent_key] / units_per_em * fontsize * dpi / 72
-                min_descent = -table[descent_key] / units_per_em * fontsize * dpi / 72
-                break
+            if hasattr(renderer, '_get_font_height_metrics'):
+                # TODO: This is a temporary internal method call (for _backend_pdf_ps to
+                # support AFM files) until we design a proper API for the backends.
+                min_ascent, min_descent, line_gap = renderer._get_font_height_metrics(
+                    self._fontproperties)
+            if min_ascent is None:
+                font = get_font(fontManager._find_fonts_by_props(self._fontproperties))
+                possible = [
+                    ('OS/2', 'sTypoLineGap', 'sTypoAscender', 'sTypoDescender'),
+                    ('hhea', 'lineGap', 'ascent', 'descent')
+                ]
+                for table_name, linegap_key, ascent_key, descent_key in possible:
+                    table = font.get_sfnt_table(table_name)
+                    if table is None:
+                        continue
+                    # Rescale to font size/DPI if the metrics were available.
+                    fontsize = self._fontproperties.get_size_in_points()
+                    units_per_em = font.get_sfnt_table('head')['unitsPerEm']
+                    scale = 1 / units_per_em * fontsize * dpi / 72
+                    line_gap = table[linegap_key] * scale
+                    min_ascent = table[ascent_key] * scale
+                    min_descent = -table[descent_key] * scale
+                    break
         if None in (min_ascent, min_descent):
             # Fallback to font measurement.
             _, h, min_descent = _get_text_metrics_with_cache(

diff --git a/lib/mpl_toolkits/axisartist/tests/test_floating_axes.py b/lib/mpl_toolkits/axisartist/tests/test_floating_axes.py
@@ -63,7 +63,7 @@ def test_curvelinear3():
     l.set_clip_path(ax1.patch)
 
 
-@image_comparison(['curvelinear4.png'], style='mpl20')
+@image_comparison(['curvelinear4.png'], style='mpl20', tol=0.04)
 def test_curvelinear4():
     fig = plt.figure(figsize=(5, 5))
 

diff --git a/lib/mpl_toolkits/axisartist/tests/test_grid_helper_curvelinear.py b/lib/mpl_toolkits/axisartist/tests/test_grid_helper_curvelinear.py
@@ -78,7 +78,7 @@ def inverted(self):
     ax1.grid(True)
 
 
-@image_comparison(['polar_box.png'], style='mpl20')
+@image_comparison(['polar_box.png'], style='mpl20', tol=0.04)
 def test_polar_box():
     plt.rcParams.update({"xtick.direction": "inout", "ytick.direction": "out"})
     fig = plt.figure(figsize=(5, 5))
@@ -138,7 +138,7 @@ def test_polar_box():
     ax1.grid(True)
 
 
-@image_comparison(['axis_direction.png'], style='mpl20')
+@image_comparison(['axis_direction.png'], style='mpl20', tol=0.04)
 def test_axis_direction():
     fig = plt.figure(figsize=(5, 5))
 

diff --git a/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py b/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py
@@ -2878,7 +2878,7 @@ def _make_triangulation_data():
 
 
 @mpl3d_image_comparison(['scale3d_artists_log.png'], style='mpl20',
-                        remove_text=False, tol=0.03)
+                        remove_text=False, tol=0.032)
 def test_scale3d_artists_log():
     """Test all 3D artist types with log scale."""
     fig = plt.figure(figsize=(16, 12))

diff --git a/pyproject.toml b/pyproject.toml
@@ -49,7 +49,7 @@ requires-python = ">=3.11"
 dev = [
     "meson-python>=0.13.2,!=0.17.*",
     "pybind11>=2.13.2,!=2.13.3",
-    "setuptools_scm>=7",
+    "setuptools_scm>=7,<10",
     # Not required by us but setuptools_scm without a version, cso _if_
     # installed, then setuptools_scm 8 requires at least this version.
     # Unfortunately, we can't do a sort of minimum-if-installed dependency, so
@@ -75,7 +75,7 @@ requires = [
     # you really need it and aren't using an sdist.
     "meson-python>=0.13.2,!=0.17.*",
     "pybind11>=2.13.2,!=2.13.3",
-    "setuptools_scm>=7",
+    "setuptools_scm>=7,<10",
 ]
 
 [tool.meson-python.args]

diff --git a/requirements/dev/build-requirements.txt b/requirements/dev/build-requirements.txt
@@ -1,3 +1,3 @@
 pybind11>=2.13.2,!=2.13.3
 meson-python
-setuptools-scm
+setuptools-scm<10
diff --git a/requirements/testing/mypy.txt b/requirements/testing/mypy.txt
@@ -22,5 +22,5 @@ packaging>=20.0
 pillow>=9
 pyparsing>=3
 python-dateutil>=2.7
-setuptools_scm>=7
+setuptools_scm>=7,<10
 setuptools>=64