Ignore STOP and CLOSPOLY codes when calculating path extents

dstansby · dstansby · commit dc681329b638 · 2021-01-02T16:23:13.000Z
diff --git a/lib/matplotlib/path.py b/lib/matplotlib/path.py
@@ -95,6 +95,9 @@ class Path:
                              CURVE4: 3,
                              CLOSEPOLY: 1}
 
+    # A list of path codes for which the vertices are ignored
+    IGNORED_CODES = [STOP, CLOSEPOLY]
+
     def __init__(self, vertices, codes=None, _interpolation_steps=1,
                  closed=False, readonly=False):
         """
@@ -620,11 +623,20 @@ def get_extents(self, transform=None, **kwargs):
             self = transform.transform_path(self)
         if self.codes is None:
             xys = self.vertices
+        # Short cut the case with only straight lines
         elif len(np.intersect1d(self.codes, [Path.CURVE3, Path.CURVE4])) == 0:
-            xys = self.vertices[self.codes != Path.CLOSEPOLY]
+            draw_idxs = np.in1d(self.codes, Path.LINETO)
+            # Include the start and end point of each line
+            draw_idxs = draw_idxs | np.roll(draw_idxs, -1)
+            # Add in commands that aren't ignored
+            # (in the straight line case here this is only MOVETO)
+            draw_idxs = draw_idxs | ~np.in1d(self.codes, Path.IGNORED_CODES)
+            xys = self.vertices[draw_idxs]
         else:
             xys = []
             for curve, code in self.iter_bezier(**kwargs):
+                if code in Path.IGNORED_CODES:
+                    continue
                 # places where the derivative is zero can be extrema
                 _, dzeros = curve.axis_aligned_extrema()
                 # as can the ends of the curve
diff --git a/lib/matplotlib/tests/test_path.py b/lib/matplotlib/tests/test_path.py
@@ -102,6 +102,15 @@ def test_exact_extents(path, extents):
     assert np.all(path.get_extents().extents == extents)
 
 
+@pytest.mark.parametrize('ignored_code', [Path.CLOSEPOLY, Path.STOP])
+def test_extents_with_ignored_codes(ignored_code):
+    # Check that STOP and CLOSEPOLY points are ignored when caclulating extents
+    path = Path([[0, 0],
+                 [1, 1],
+                 [2, 2]], [Path.MOVETO, Path.MOVETO, ignored_code])
+    assert np.all(path.get_extents().extents == (0., 0., 1., 1.))
+
+
 def test_point_in_path_nan():
     box = np.array([[0, 0], [1, 0], [1, 1], [0, 1], [0, 0]])
     p = Path(box)
