From de8369be50208f94db5f90ebe33474ebafd7a8e6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20Scho=CC=88nberger?= <jschoenberger@demuc.de>
Date: Mon, 23 Apr 2012 16:20:49 +0200
Subject: [PATCH] added draw circle and ellipse functions

---
 skimage/draw/_draw.pyx          | 65 +++++++++++++++++++++++++++++++++
 skimage/draw/draw.py            |  2 +-
 skimage/draw/tests/test_draw.py | 54 ++++++++++++++++++++++++++-
 3 files changed, 119 insertions(+), 2 deletions(-)

diff --git a/skimage/draw/_draw.pyx b/skimage/draw/_draw.pyx
index 44bfea55..6f6c955f 100644
--- a/skimage/draw/_draw.pyx
+++ b/skimage/draw/_draw.pyx
@@ -1,5 +1,6 @@
 import numpy as np
 import math
+from libc.math cimport sqrt
 cimport numpy as np
 cimport cython
 
@@ -121,3 +122,67 @@ def polygon(verts, shape=None):
                 cc.append(c)
 
     return np.array(rr), np.array(cc)
+
+@cython.boundscheck(False)
+@cython.wraparound(False)
+@cython.nonecheck(False)
+@cython.cdivision(True)
+def ellipse(double cy, double cx, double b, double a, shape=None):
+    """Generate coordinates of pixels within ellipse.
+
+    Parameters
+    ----------
+    cy, cx : double
+        centre coordinate of ellipse
+    b, a: double
+        minor and major semi-axes. (x/a)**2 + (y/b)**2 = 1
+
+    Returns
+    -------
+    rr, cc : ndarray of int
+        Pixel coordinates of ellipse.
+        May be used to directly index into an array, e.g.
+        ``img[rr, cc] = 1``.
+    """
+    cdef int minr = <int>max(0, cy-b)
+    cdef int maxr = <int>math.ceil(cy+b)
+    cdef int minc = <int>max(0, cx-a)
+    cdef int maxc = <int>math.ceil(cx+a)
+
+    # make sure output coordinates do not exceed image size
+    if shape is not None:
+        maxr = min(shape[0]-1, maxr)
+        maxc = min(shape[1]-1, maxc)
+
+    cdef int r, c
+
+    #: output coordinate arrays
+    rr = list()
+    cc = list()
+
+    for r in range(minr, maxr+1):
+        for c in range(minc, maxc+1):
+            if sqrt(((r - cy)/b)**2 + ((c - cx)/a)**2) < 1:
+                rr.append(r)
+                cc.append(c)
+
+    return np.array(rr), np.array(cc)
+
+def circle(double cy, double cx, double radius, shape=None):
+    """Generate coordinates of pixels within circle.
+
+    Parameters
+    ----------
+    cy, cx : double
+        centre coordinate of circle
+    radius: double
+        radius of circle
+
+    Returns
+    -------
+    rr, cc : ndarray of int
+        Pixel coordinates of ellipse.
+        May be used to directly index into an array, e.g.
+        ``img[rr, cc] = 1``.
+    """
+    return ellipse(cy, cx, radius, radius, shape)
diff --git a/skimage/draw/draw.py b/skimage/draw/draw.py
index 5a7f9339..a18cdeb6 100644
--- a/skimage/draw/draw.py
+++ b/skimage/draw/draw.py
@@ -3,4 +3,4 @@ Methods to draw on arrays.
 
 """
 
-from ._draw import bresenham, polygon
+from ._draw import bresenham, polygon, ellipse, circle
diff --git a/skimage/draw/tests/test_draw.py b/skimage/draw/tests/test_draw.py
index 80873981..ed309cf6 100644
--- a/skimage/draw/tests/test_draw.py
+++ b/skimage/draw/tests/test_draw.py
@@ -1,7 +1,7 @@
 from numpy.testing import assert_array_equal
 import numpy as np
 
-from skimage.draw import bresenham, polygon
+from skimage.draw import bresenham, polygon, circle, ellipse
 
 
 def test_bresenham_horizontal():
@@ -116,6 +116,58 @@ def test_polygon_exceed():
 
     assert_array_equal(img, img_)
 
+def test_circle():
+    img = np.zeros((15, 15), 'uint8')
+
+    rr, cc = circle(7, 7, 6)
+    img[rr,cc] = 1
+
+    img_ = np.array(
+      [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0],
+       [0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
+       [0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
+    )
+
+    assert_array_equal(img, img_)
+
+def test_ellipse():
+    img = np.zeros((15, 15), 'uint8')
+
+    rr, cc = ellipse(7, 7, 3, 7)
+    img[rr,cc] = 1
+
+    img_ = np.array(
+      [[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
+       [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
+       [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
+       [0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
+       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
+    )
+
+    assert_array_equal(img, img_)
+
 
 if __name__ == "__main__":
     from numpy.testing import run_module_suite