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Add corner coordinate helper methods to Ellipse/Rectangle #21977

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Merged
merged 1 commit into from
Jan 5, 2022
Merged

Add corner coordinate helper methods to Ellipse/Rectangle #21977

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22 changes: 22 additions & 0 deletions lib/matplotlib/patches.py
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Original file line number Diff line number Diff line change
Expand Up @@ -806,6 +806,18 @@ def get_xy(self):
"""Return the left and bottom coords of the rectangle as a tuple."""
return self._x0, self._y0

def get_corners(self):
"""
Return the corners of the rectangle, moving anti-clockwise from
(x0, y0).
"""
return self.get_patch_transform().transform(
[(0, 0), (1, 0), (1, 1), (0, 1)])

def get_center(self):
"""Return the centre of the rectangle."""
return self.get_patch_transform().transform((0.5, 0.5))

def get_width(self):
"""Return the width of the rectangle."""
return self._width
Expand Down Expand Up @@ -1657,6 +1669,16 @@ def get_angle(self):

angle = property(get_angle, set_angle)

def get_corners(self):
"""
Return the corners of the ellipse bounding box.

The bounding box orientation is moving anti-clockwise from the
lower left corner defined before rotation.
"""
return self.get_patch_transform().transform(
[(-1, -1), (1, -1), (1, 1), (-1, 1)])


class Annulus(Patch):
"""
Expand Down
50 changes: 49 additions & 1 deletion lib/matplotlib/tests/test_patches.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
import pytest

import matplotlib as mpl
from matplotlib.patches import (Annulus, Patch, Polygon, Rectangle,
from matplotlib.patches import (Annulus, Ellipse, Patch, Polygon, Rectangle,
FancyArrowPatch)
from matplotlib.testing.decorators import image_comparison, check_figures_equal
from matplotlib.transforms import Bbox
Expand Down Expand Up @@ -54,6 +54,54 @@ def test_Polygon_close():
assert_array_equal(p.get_xy(), xyclosed)


def test_corner_center():
loc = [10, 20]
width = 1
height = 2

# Rectangle
# No rotation
corners = ((10, 20), (11, 20), (11, 22), (10, 22))
rect = Rectangle(loc, width, height)
assert_array_equal(rect.get_corners(), corners)
assert_array_equal(rect.get_center(), (10.5, 21))

# 90 deg rotation
corners_rot = ((10, 20), (10, 21), (8, 21), (8, 20))
rect.set_angle(90)
assert_array_equal(rect.get_corners(), corners_rot)
assert_array_equal(rect.get_center(), (9, 20.5))

# Rotation not a multiple of 90 deg
theta = 33
t = mtransforms.Affine2D().rotate_around(*loc, np.deg2rad(theta))
corners_rot = t.transform(corners)
rect.set_angle(theta)
assert_almost_equal(rect.get_corners(), corners_rot)

# Ellipse
loc = [loc[0] + width / 2,
loc[1] + height / 2]
ellipse = Ellipse(loc, width, height)

# No rotation
assert_array_equal(ellipse.get_corners(), corners)

# 90 deg rotation
corners_rot = ((11.5, 20.5), (11.5, 21.5), (9.5, 21.5), (9.5, 20.5))
ellipse.set_angle(90)
assert_array_equal(ellipse.get_corners(), corners_rot)
# Rotation shouldn't change ellipse center
assert_array_equal(ellipse.get_center(), loc)

# Rotation not a multiple of 90 deg
theta = 33
t = mtransforms.Affine2D().rotate_around(*loc, np.deg2rad(theta))
corners_rot = t.transform(corners)
ellipse.set_angle(theta)
assert_almost_equal(ellipse.get_corners(), corners_rot)


def test_rotate_rect():
loc = np.asarray([1.0, 2.0])
width = 2
Expand Down