Refactor pnpoly function in Cython and add to shared package

skimage/draw/_draw.pyx

@@ -3,11 +3,7 @@ import math
 from libc.math cimport sqrt
 cimport numpy as np
 cimport cython
-
-
-cdef extern from "../morphology/_pnpoly.h":
-     int pnpoly(int nr_verts, double *xp, double *yp,
-                double x, double y)
+from skimage._shared.geometry cimport point_in_polygon
 
 
 @cython.boundscheck(False)
@@ -119,7 +115,7 @@ def polygon(y, x, shape=None):
 
     for r in range(minr, maxr+1):
         for c in range(minc, maxc+1):
-            if pnpoly(nr_verts, cptr, rptr, c, r):
+            if point_in_polygon(nr_verts, cptr, rptr, c, r):
                 rr.append(r)
                 cc.append(c)
 

skimage/draw/setup.py

@@ -15,7 +15,7 @@ def configuration(parent_package='', top_path=None):
     cython(['_draw.pyx'], working_path=base_path)
 
     config.add_extension('_draw', sources=['_draw.c'],
-                         include_dirs=[get_numpy_include_dirs()])
+                         include_dirs=[get_numpy_include_dirs(), '../shared'])
 
     return config