Add an rcParam to restore old kerning behaviour.

This is enabled for the classic test style, so that the 100 or so old
images do not need to be regenerated.

Author: QuLogic

lib/matplotlib/font_manager.py

@@ -1327,7 +1327,8 @@ def is_opentype_cff_font(filename):
 def get_font(filename, hinting_factor=None):
     if hinting_factor is None:
         hinting_factor = rcParams['text.hinting_factor']
-    return _get_font(os.fspath(filename), hinting_factor)
+    return _get_font(os.fspath(filename), hinting_factor,
+                     _kerning_factor=rcParams['text.kerning_factor'])
 
 
 def _rebuild():

lib/matplotlib/mpl-data/stylelib/_classic_test_patch.mplstyle

@@ -1,4 +1,6 @@
 # This patch should go on top of the "classic" style and exists solely to avoid
 # changing baseline images.
 
+text.kerning_factor : 6
+
 ytick.alignment: center_baseline

lib/matplotlib/rcsetup.py

@@ -1091,6 +1091,7 @@ def _validate_linestyle(ls):
     'text.latex.preview':  [False, validate_bool],
     'text.hinting':        ['auto', validate_hinting],
     'text.hinting_factor': [8, validate_int],
+    'text.kerning_factor': [0, validate_int],
     'text.antialiased':    [True, validate_bool],
 
     'mathtext.cal':            ['cursive', validate_font_properties],

lib/matplotlib/tests/test_artist.py

@@ -201,6 +201,9 @@ def test_remove():
 
 @image_comparison(["default_edges.png"], remove_text=True, style='default')
 def test_default_edges():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     fig, [[ax1, ax2], [ax3, ax4]] = plt.subplots(2, 2)
 
     ax1.plot(np.arange(10), np.arange(10), 'x',

lib/matplotlib/tests/test_axes.py

@@ -48,6 +48,9 @@ def test_get_labels():
 
 @image_comparison(['acorr.png'], style='mpl20')
 def test_acorr():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     np.random.seed(19680801)
     n = 512
     x = np.random.normal(0, 1, n).cumsum()
@@ -5730,6 +5733,9 @@ def test_axisbelow():
 
 @image_comparison(['titletwiny.png'], style='mpl20')
 def test_titletwiny():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     # Test that title is put above xlabel if xlabel at top
     fig, ax = plt.subplots()
     fig.subplots_adjust(top=0.8)

lib/matplotlib/tests/test_image.py

@@ -27,6 +27,9 @@
 @image_comparison(['image_interps'], style='mpl20')
 def test_image_interps():
     'make the basic nearest, bilinear and bicubic interps'
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     X = np.arange(100)
     X = X.reshape(5, 20)
 

lib/matplotlib/tests/test_legend.py

@@ -188,6 +188,9 @@ def test_legend_expand():
 
 @image_comparison(['hatching'], remove_text=True, style='default')
 def test_hatching():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     fig, ax = plt.subplots()
 
     # Patches

lib/matplotlib/tests/test_text.py

@@ -130,6 +130,9 @@ def test_multiline():
 
 @image_comparison(['multiline2'], style='mpl20')
 def test_multiline2():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     fig, ax = plt.subplots()
 
     ax.set_xlim([0, 1.4])
@@ -580,6 +583,9 @@ def test_annotation_update():
 
 @image_comparison(['large_subscript_title.png'], style='mpl20')
 def test_large_subscript_title():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     fig, axs = plt.subplots(1, 2, figsize=(9, 2.5), constrained_layout=True)
     ax = axs[0]
     ax.set_title(r'$\sum_{i} x_i$')

lib/matplotlib/tests/test_widgets.py

@@ -264,6 +264,9 @@ def test_CheckButtons():
 
 @image_comparison(['check_radio_buttons.png'], style='mpl20', remove_text=True)
 def test_check_radio_buttons_image():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     get_ax()
     plt.subplots_adjust(left=0.3)
     rax1 = plt.axes([0.05, 0.7, 0.15, 0.15])

lib/mpl_toolkits/tests/test_axisartist_axis_artist.py

@@ -26,6 +26,9 @@ def test_ticks():
 
 @image_comparison(['axis_artist_labelbase.png'], style='default')
 def test_labelbase():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     fig, ax = plt.subplots()
 
     ax.plot([0.5], [0.5], "o")
@@ -40,6 +43,9 @@ def test_labelbase():
 
 @image_comparison(['axis_artist_ticklabels.png'], style='default')
 def test_ticklabels():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     fig, ax = plt.subplots()
 
     ax.xaxis.set_visible(False)
@@ -72,6 +78,9 @@ def test_ticklabels():
 
 @image_comparison(['axis_artist.png'], style='default')
 def test_axis_artist():
+    # Remove this line when this test image is regenerated.
+    plt.rcParams['text.kerning_factor'] = 6
+
     fig, ax = plt.subplots()
 
     ax.xaxis.set_visible(False)