Merge pull request SciTools#1251 from QuLogic/cython-trace

Convert trace.cpp to Cython

lib/cartopy/_crs.pxd

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2010 - 2016, Met Office
+# (C) British Crown Copyright 2010 - 2018, Met Office
 #
 # This file is part of cartopy.
 #
@@ -16,8 +16,7 @@
 # along with cartopy.  If not, see <https://www.gnu.org/licenses/>.
 
 
-cdef extern from "proj_api.h":
-    ctypedef void *projPJ
+from ._proj4 cimport projPJ
 
 
 cdef class CRS:

lib/cartopy/_crs.pyx

@@ -35,17 +35,9 @@ cimport numpy as np
 from cython.operator cimport dereference as deref
 
 
-cdef extern from "proj_api.h":
-    ctypedef void *projPJ
-    projPJ pj_init_plus(char *)
-    void pj_free(projPJ)
-    int pj_transform(projPJ, projPJ, long, int, double *, double *, double *)
-    int pj_is_latlong(projPJ)
-    char *pj_strerrno(int)
-    int *pj_get_errno_ref()
-    char *pj_get_release()
-    double DEG_TO_RAD
-    double RAD_TO_DEG
+from ._proj4 cimport (pj_init_plus, pj_free, pj_transform, pj_is_latlong,
+                      pj_strerrno, pj_get_errno_ref, pj_get_release,
+                      DEG_TO_RAD, RAD_TO_DEG)
 
 
 cdef double NAN = float('nan')

lib/cartopy/_proj4.pxd

@@ -0,0 +1,39 @@
+# (C) British Crown Copyright 2018, Met Office
+#
+# This file is part of cartopy.
+#
+# cartopy is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the
+# Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cartopy is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with cartopy.  If not, see <https://www.gnu.org/licenses/>.
+
+"""
+This file declares the Proj API, version 4.
+
+"""
+
+
+cdef extern from "proj_api.h":
+    ctypedef void *projPJ
+    ctypedef struct projLP:
+        double u
+        double v
+
+    projPJ pj_init_plus(char *) nogil
+    void pj_free(projPJ) nogil
+    void pj_get_spheroid_defn(projPJ, double *, double *) nogil
+    int pj_transform(projPJ, projPJ, long, int, double *, double *, double *) nogil
+    int pj_is_latlong(projPJ) nogil
+    char *pj_strerrno(int) nogil
+    int *pj_get_errno_ref() nogil
+    char *pj_get_release() nogil
+    cdef double DEG_TO_RAD
+    cdef double RAD_TO_DEG