Made radius scale invariant

daniel-s-ingram · QuLogic · commit 5725c83798be · 2020-09-10T23:39:33.000-04:00
diff --git a/examples/lines_bars_and_markers/angle_arc.py b/examples/lines_bars_and_markers/angle_arc.py
@@ -15,13 +15,15 @@
 vec2 = ax.arrow(0, 0, -1, 2, head_width=0.05)
 
 
-def get_vector_angle(vec):
+def get_vector_angle(trans, vec):
     """
     Finds the angle of a FancyArrow. Probably
     a better way to do this.
 
     Parameters
     ----------
+    trans : matplotlib.transforms.CompositeGenericTransform
+        Transformation from data coords to axes coords
     vec : matplotlib.patches.FancyArrow
 
     Returns
@@ -30,7 +32,8 @@ def get_vector_angle(vec):
         Angle in radians between +x axis
         and vec.
     """
-    xy = vec.get_xy()
+    #Shift axes coords to -0.5, 0.5 for proper angle calculation
+    xy = trans.transform(vec.get_xy()) - 0.5
     dx = max(xy[:, 0], key=abs) - min(xy[:, 0], key=abs)
     dy = max(xy[:, 1], key=abs) - min(xy[:, 1], key=abs)
     return atan2(dy, dx)*180/pi
@@ -54,20 +57,22 @@ def draw_arc_between_vectors(ax, vec1, vec2):
     vec2 : matplotlib.patches.FancyArrow
         Vector 2
     """
-    x0, y0 = ax.transData.transform((0, 0))
-    x1, y1 = ax.transData.transform((1, 1))
+    x0, y0 = ax.transAxes.transform((0, 0))
+    x1, y1 = ax.transAxes.transform((1, 1))
     dx = x1 - x0
     dy = y1 - y0
     d = sqrt(dx**2 + dy**2)
-    width = d/dx
-    height = d/dy
-    norm = sqrt(width**2 + height**2)
-    width /= norm
-    height /= norm
-    theta1 = get_vector_angle(vec1)
-    theta2 = get_vector_angle(vec2)
+    width = 0.1*d/dx
+    height = 0.1*d/dy
+    trans = ax.transData + ax.transAxes.inverted()
+    theta1 = get_vector_angle(trans, vec1)
+    theta2 = get_vector_angle(trans, vec2)
     arc = mpatches.Arc(
-        (0, 0), width, height, theta1=theta1, theta2=theta2, gid="angle_arc")
+        trans.transform((0, 0)),
+        width, height,
+        theta1=theta1, theta2=theta2,
+        gid="angle_arc",
+        transform=ax.transAxes)
     [p.remove() for p in ax.patches if p.get_gid() == "angle_arc"]
     ax.add_patch(arc)
 
