Backport PR #16770: Fix tuple markers

tacaswell · meeseeksmachine · commit dc81103dec1c · 2020-03-16T17:33:28.000Z
diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
@@ -347,6 +347,7 @@ def _set_tuple_marker(self):
             self._joinstyle = 'bevel'
         else:
             raise ValueError(f"Unexpected tuple marker: {marker}")
+        self._transform = Affine2D().scale(0.5).rotate_deg(rotation)
 
     def _set_mathtext_path(self):
         """
diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
@@ -1,6 +1,8 @@
 import numpy as np
+import matplotlib.pyplot as plt
 from matplotlib import markers
 from matplotlib.path import Path
+from matplotlib.testing.decorators import check_figures_equal
 
 import pytest
 
@@ -26,3 +28,108 @@ def test_marker_path():
     path = Path([[0, 0], [1, 0]], [Path.MOVETO, Path.LINETO])
     # Checking this doesn't fail.
     marker_style.set_marker(path)
+
+
+class UnsnappedMarkerStyle(markers.MarkerStyle):
+    """
+    A MarkerStyle where the snap threshold is force-disabled.
+
+    This is used to compare to polygon/star/asterisk markers which do not have
+    any snap threshold set.
+    """
+    def _recache(self):
+        super()._recache()
+        self._snap_threshold = None
+
+
+@check_figures_equal()
+def test_poly_marker(fig_test, fig_ref):
+    ax_test = fig_test.add_subplot()
+    ax_ref = fig_ref.add_subplot()
+
+    # Note, some reference sizes must be different because they have unit
+    # *length*, while polygon markers are inscribed in a circle of unit
+    # *radius*. This introduces a factor of np.sqrt(2), but since size is
+    # squared, that becomes 2.
+    size = 20**2
+
+    # Squares
+    ax_test.scatter([0], [0], marker=(4, 0, 45), s=size)
+    ax_ref.scatter([0], [0], marker='s', s=size/2)
+
+    # Diamonds, with and without rotation argument
+    ax_test.scatter([1], [1], marker=(4, 0), s=size)
+    ax_ref.scatter([1], [1], marker=UnsnappedMarkerStyle('D'), s=size/2)
+    ax_test.scatter([1], [1.5], marker=(4, 0, 0), s=size)
+    ax_ref.scatter([1], [1.5], marker=UnsnappedMarkerStyle('D'), s=size/2)
+
+    # Pentagon, with and without rotation argument
+    ax_test.scatter([2], [2], marker=(5, 0), s=size)
+    ax_ref.scatter([2], [2], marker=UnsnappedMarkerStyle('p'), s=size)
+    ax_test.scatter([2], [2.5], marker=(5, 0, 0), s=size)
+    ax_ref.scatter([2], [2.5], marker=UnsnappedMarkerStyle('p'), s=size)
+
+    # Hexagon, with and without rotation argument
+    ax_test.scatter([3], [3], marker=(6, 0), s=size)
+    ax_ref.scatter([3], [3], marker='h', s=size)
+    ax_test.scatter([3], [3.5], marker=(6, 0, 0), s=size)
+    ax_ref.scatter([3], [3.5], marker='h', s=size)
+
+    # Rotated hexagon
+    ax_test.scatter([4], [4], marker=(6, 0, 30), s=size)
+    ax_ref.scatter([4], [4], marker='H', s=size)
+
+    # Octagons
+    ax_test.scatter([5], [5], marker=(8, 0, 22.5), s=size)
+    ax_ref.scatter([5], [5], marker=UnsnappedMarkerStyle('8'), s=size)
+
+    ax_test.set(xlim=(-0.5, 5.5), ylim=(-0.5, 5.5))
+    ax_ref.set(xlim=(-0.5, 5.5), ylim=(-0.5, 5.5))
+
+
+def test_star_marker():
+    # We don't really have a strict equivalent to this marker, so we'll just do
+    # a smoke test.
+    size = 20**2
+
+    fig, ax = plt.subplots()
+    ax.scatter([0], [0], marker=(5, 1), s=size)
+    ax.scatter([1], [1], marker=(5, 1, 0), s=size)
+    ax.set(xlim=(-0.5, 0.5), ylim=(-0.5, 1.5))
+
+
+# The asterisk marker is really a star with 0-size inner circle, so the ends
+# are corners and get a slight bevel. The reference markers are just singular
+# lines without corners, so they have no bevel, and we need to add a slight
+# tolerance.
+@check_figures_equal(tol=1.45)
+def test_asterisk_marker(fig_test, fig_ref, request):
+    ax_test = fig_test.add_subplot()
+    ax_ref = fig_ref.add_subplot()
+
+    # Note, some reference sizes must be different because they have unit
+    # *length*, while asterisk markers are inscribed in a circle of unit
+    # *radius*. This introduces a factor of np.sqrt(2), but since size is
+    # squared, that becomes 2.
+    size = 20**2
+
+    def draw_ref_marker(y, style, size):
+        # As noted above, every line is doubled. Due to antialiasing, these
+        # doubled lines make a slight difference in the .png results.
+        ax_ref.scatter([y], [y], marker=UnsnappedMarkerStyle(style), s=size)
+        if request.getfixturevalue('ext') == 'png':
+            ax_ref.scatter([y], [y], marker=UnsnappedMarkerStyle(style),
+                           s=size)
+
+    # Plus
+    ax_test.scatter([0], [0], marker=(4, 2), s=size)
+    draw_ref_marker(0, '+', size)
+    ax_test.scatter([0.5], [0.5], marker=(4, 2, 0), s=size)
+    draw_ref_marker(0.5, '+', size)
+
+    # Cross
+    ax_test.scatter([1], [1], marker=(4, 2, 45), s=size)
+    draw_ref_marker(1, 'x', size/2)
+
+    ax_test.set(xlim=(-0.5, 1.5), ylim=(-0.5, 1.5))
+    ax_ref.set(xlim=(-0.5, 1.5), ylim=(-0.5, 1.5))
