Add affine transform primitives to markers

Added, translated, scaled, and rotated methods with test.

Author: deep-jkl

lib/matplotlib/markers.py

@@ -419,7 +419,7 @@ def get_user_transform(self):
         if self._user_transform is not None:
             return self._user_transform.frozen()
 
-    def transformed(self, transform:Affine2D):
+    def transformed(self, transform: Affine2D):
         """
         Return new marker with combined transformation.
 
@@ -442,22 +442,65 @@ def rotated(self, deg=None, rad=None):
         Parameters
         ----------
         deg : float, default: None
+            - use this parameter to specify rotation angle in degrees.
 
         rad : float, default: None
+            - use this parameter to specify rotation angle in radians.
+
+        Note: you must specify exactly one of deg or rad.
         """
         if not ((deg is None) ^ (rad is None)):
-            raise Exception("Only one of deg or rad shall be used.")
-        
-        _transform = self._user_transform or Affine2D()
+            raise ValueError("Exactly one of deg or rad shall be used.")
+
+        new_marker = MarkerStyle(self)
+        if new_marker._user_transform is None:
+            new_marker._user_transform = Affine2D()
 
-        if deg is not None: 
-            _transform = _transform.rotate_deg(deg)
-        
+        if deg is not None:
+            new_marker._user_transform.rotate_deg(deg)
         if rad is not None:
-            _transform = _transform.rotate(rad)
+            new_marker._user_transform.rotate(rad)
+
+        return new_marker
+
+    def scaled(self, sx, sy=None):
+        """
+        Return new marker scaled by specified scale factors.
+
+        If *sy* is None, the same scale is applied in both the *x*- and
+        *y*-directions.
+
+        Parameters
+        ----------
+        sx : float
+        - *x*-direction scaling factor.
+
+        sy : float, default: None
+        - *y*-direction scaling factor.
+        """
+        if sy is None:
+            sy = sx
+
+        new_marker = MarkerStyle(self)
+        _transform = new_marker._user_transform or Affine2D()
+        new_marker._user_transform = _transform.scale(sx, sy)
+        return new_marker
+
+    def translated(self, tx, ty):
+        """
+        Return new marker translated by tx and ty.
 
+        Parameters
+        ----------
+        tx : float
+
+        ty : float
+
+        """
         new_marker = MarkerStyle(self)
-        new_marker._user_transform = _transform
+        _transform = new_marker._user_transform or Affine2D()
+        new_marker._user_transform = _transform.translate(tx, ty)
+        return new_marker
 
     def _set_nothing(self):
         self._filled = False

lib/matplotlib/tests/test_marker.py

@@ -206,12 +206,47 @@ def test_marker_clipping(fig_ref, fig_test):
     ax_ref.axis('off')
     ax_test.axis('off')
 
+
 @pytest.mark.parametrize("marker,transform,expected", [
-    (markers.MarkerStyle("o"), Affine2D().translate(1,1), Affine2D().translate(1,1)),
-    (markers.MarkerStyle("o", transform=Affine2D().translate(1,1)), Affine2D().translate(1,1), Affine2D().translate(2,2)),
+    (markers.MarkerStyle("o"), Affine2D().translate(1, 1),
+        Affine2D().translate(1, 1)),
+    (markers.MarkerStyle("o", transform=Affine2D().translate(1, 1)),
+        Affine2D().translate(1, 1), Affine2D().translate(2, 2)),
+    # (markers.MarkerStyle("$|||$", transform=Affine2D().translate(1, 1)),
+    #  Affine2D().translate(1, 1), Affine2D().translate(2, 2)),
+    (markers.MarkerStyle(
+        markers.TICKLEFT, transform=Affine2D().translate(1, 1)),
+        Affine2D().translate(1, 1), Affine2D().translate(2, 2)),
 ])
 def test_marker_transformed(marker, transform, expected):
     new_marker = marker.transformed(transform)
     assert new_marker is not marker
     assert new_marker.get_user_transform() == expected
-    assert marker.get_user_transform() is not new_marker.get_user_transform()
+    assert marker._user_transform is not new_marker._user_transform
+
+
+def test_marker_rotated_invalid():
+    marker = markers.MarkerStyle("o")
+    with pytest.raises(ValueError):
+        new_marker = marker.rotated()
+        new_marker = marker.rotated(deg=10, rad=10)
+
+
+@pytest.mark.parametrize("marker,deg,rad,expected", [
+    (markers.MarkerStyle("o"), 10, None, Affine2D().rotate_deg(10)),
+    (markers.MarkerStyle("o"), None, 0.01, Affine2D().rotate(0.01)),
+    (markers.MarkerStyle("o", transform=Affine2D().translate(1, 1)),
+        10, None, Affine2D().translate(1, 1).rotate_deg(10)),
+    (markers.MarkerStyle("o", transform=Affine2D().translate(1, 1)),
+        None, 0.01, Affine2D().translate(1, 1).rotate(0.01)),
+    # (markers.MarkerStyle("$|||$", transform=Affine2D().translate(1, 1)),
+    #   10, None, Affine2D().translate(1, 1).rotate_deg(10)),
+    (markers.MarkerStyle(
+        markers.TICKLEFT, transform=Affine2D().translate(1, 1)),
+        10, None, Affine2D().translate(1, 1).rotate_deg(10)),
+])
+def test_marker_rotated_deg(marker, deg, rad, expected):
+    new_marker = marker.rotated(deg=deg, rad=rad)
+    assert new_marker is not marker
+    assert new_marker.get_user_transform() == expected
+    assert marker._user_transform is not new_marker._user_transform