Merge pull request matplotlib#19460 from QuLogic/bracket-angle

ENH: Implement angles for bracket arrow styles.

Author: tacaswell

doc/users/next_whats_new/bracket_angle.rst

@@ -0,0 +1,25 @@
+Angles on Bracket arrow styles
+------------------------------
+
+Angles specified on the *Bracket* arrow styles (``]-[``, ``]-``, ``-[``, or
+``|-|`` passed to *arrowstyle* parameter of `.FancyArrowPatch`) are now
+applied. Previously, the *angleA* and *angleB* options were allowed, but did
+nothing.
+
+.. plot::
+
+    import matplotlib.pyplot as plt
+    import matplotlib.patches as mpatches
+
+    fig, ax = plt.subplots()
+    ax.set(xlim=(0, 1), ylim=(-1, 4))
+
+    for i, stylename in enumerate((']-[', '|-|')):
+        for j, angle in enumerate([-30, 60]):
+            arrowstyle = f'{stylename},angleA={angle},angleB={-angle}'
+            patch = mpatches.FancyArrowPatch((0.1, 2*i + j), (0.9, 2*i + j),
+                                             arrowstyle=arrowstyle,
+                                             mutation_scale=25)
+            ax.text(0.5, 2*i + j, arrowstyle,
+                    verticalalignment='bottom', horizontalalignment='center')
+            ax.add_patch(patch)

lib/matplotlib/patches.py

@@ -3207,7 +3207,7 @@ def __init__(self, bracketA=None, bracketB=None,
             self.scaleA, self.scaleB = scaleA, scaleB
 
         def _get_bracket(self, x0, y0,
-                         cos_t, sin_t, width, length):
+                         cos_t, sin_t, width, length, angle):
 
             # arrow from x0, y0 to x1, y1
             from matplotlib.bezier import get_normal_points
@@ -3224,6 +3224,10 @@ def _get_bracket(self, x0, y0,
                            Path.LINETO,
                            Path.LINETO]
 
+            if angle is not None:
+                trans = transforms.Affine2D().rotate_deg_around(x0, y0, angle)
+                vertices_arrow = trans.transform(vertices_arrow)
+
             return vertices_arrow, codes_arrow
 
         def transmute(self, path, mutation_size, linewidth):
@@ -3246,7 +3250,8 @@ def transmute(self, path, mutation_size, linewidth):
                 cos_t, sin_t = get_cos_sin(x1, y1, x0, y0)
                 verticesA, codesA = self._get_bracket(x0, y0, cos_t, sin_t,
                                                       self.widthA * scaleA,
-                                                      self.lengthA * scaleA)
+                                                      self.lengthA * scaleA,
+                                                      self.angleA)
                 vertices_list.append(verticesA)
                 codes_list.append(codesA)
 
@@ -3259,7 +3264,8 @@ def transmute(self, path, mutation_size, linewidth):
                 cos_t, sin_t = get_cos_sin(x1, y1, x0, y0)
                 verticesB, codesB = self._get_bracket(x0, y0, cos_t, sin_t,
                                                       self.widthB * scaleB,
-                                                      self.lengthB * scaleB)
+                                                      self.lengthB * scaleB,
+                                                      self.angleB)
                 vertices_list.append(verticesB)
                 codes_list.append(codesB)
 
@@ -3287,7 +3293,9 @@ def __init__(self,
                 Length of the bracket.
 
             angleA : float, default: None
-                Angle between the bracket and the line.
+                Angle, in degrees, between the bracket and the line. Zero is
+                perpendicular to the line, and positive measures
+                counterclockwise.
 
             widthB : float, default: 1.0
                 Width of the bracket.
@@ -3296,7 +3304,9 @@ def __init__(self,
                 Length of the bracket.
 
             angleB : float, default: None
-                Angle between the bracket and the line.
+                Angle, in degrees, between the bracket and the line. Zero is
+                perpendicular to the line, and positive measures
+                counterclockwise.
             """
             super().__init__(True, True,
                              widthA=widthA, lengthA=lengthA, angleA=angleA,
@@ -3337,7 +3347,9 @@ def __init__(self, widthB=1., lengthB=0.2, angleB=None):
                 Length of the bracket.
 
             angleB : float, default: None
-                Angle between the bracket and the line.
+                Angle, in degrees, between the bracket and the line. Zero is
+                perpendicular to the line, and positive measures
+                counterclockwise.
             """
             super().__init__(None, True,
                              widthB=widthB, lengthB=lengthB, angleB=angleB)
@@ -3356,13 +3368,17 @@ def __init__(self,
                 Width of the bracket.
 
             angleA : float, default: None
-                Angle between the bracket and the line.
+                Angle, in degrees, between the bracket and the line. Zero is
+                perpendicular to the line, and positive measures
+                counterclockwise.
 
             widthB : float, default: 1.0
                 Width of the bracket.
 
             angleB : float, default: None
-                Angle between the bracket and the line.
+                Angle, in degrees, between the bracket and the line. Zero is
+                perpendicular to the line, and positive measures
+                counterclockwise.
             """
             super().__init__(True, True,
                              widthA=widthA, lengthA=0, angleA=angleA,

lib/matplotlib/tests/baseline_images/test_arrow_patches/arrow_styles.png

@@ -119,16 +119,31 @@ def test_arrow_styles():
     styles = mpatches.ArrowStyle.get_styles()
 
     n = len(styles)
-    fig, ax = plt.subplots(figsize=(6, 10))
+    fig, ax = plt.subplots(figsize=(8, 8))
     ax.set_xlim(0, 1)
     ax.set_ylim(-1, n)
+    fig.subplots_adjust(left=0, right=1, bottom=0, top=1)
 
     for i, stylename in enumerate(sorted(styles)):
-        patch = mpatches.FancyArrowPatch((0.1, i), (0.8, i),
+        patch = mpatches.FancyArrowPatch((0.1, i), (0.45, i),
                                          arrowstyle=stylename,
                                          mutation_scale=25)
         ax.add_patch(patch)
 
+    for i, stylename in enumerate([']-[', ']-', '-[', '|-|']):
+        style = stylename
+        if stylename[0] != '-':
+            style += ',angleA=ANGLE'
+        if stylename[-1] != '-':
+            style += ',angleB=ANGLE'
+
+        for j, angle in enumerate([-30, 60]):
+            arrowstyle = style.replace('ANGLE', str(angle))
+            patch = mpatches.FancyArrowPatch((0.55, 2*i + j), (0.9, 2*i + j),
+                                             arrowstyle=arrowstyle,
+                                             mutation_scale=25)
+            ax.add_patch(patch)
+
 
 @image_comparison(['connection_styles.png'], style='mpl20', remove_text=True)
 def test_connection_styles():