Merge pull request #748 from kbevers/has_inverse

Add pj_has_inverse().

5 files changed, 12 insertions, 6 deletions

diff --git a/src/PJ_pipeline.c b/src/PJ_pipeline.c
index befc8557..2f904ab1 100644
--- a/src/PJ_pipeline.c
+++ b/src/PJ_pipeline.c
@@ -454,8 +454,7 @@ PJ *OPERATION(pipeline,0) {
     /* determine if an inverse operation is possible */
     for (i = 1; i <= nsteps; i++) {
         PJ *Q = P->opaque->pipeline[i];
-        if ( ( Q->inverted && (Q->fwd || Q->fwd3d || Q->fwd4d) ) ||
-             ( Q->inv || Q->inv3d || Q->inv4d) ) {
+        if ( pj_has_inverse(Q) ) {
             continue;
         } else {
             P->inv   = 0;
diff --git a/src/pj_internal.c b/src/pj_internal.c
index deb0c054..6bb33d64 100644
--- a/src/pj_internal.c
+++ b/src/pj_internal.c
@@ -119,7 +119,14 @@ chained calls starting out with a call to its 3D interface.
     return proj_coord_error ();
 }
 
-
+/**************************************************************************************/
+int pj_has_inverse(PJ *P) {
+/***************************************************************************************
+Check if a a PJ has an inverse.
+***************************************************************************************/
+    return ( (P->inverted && (P->fwd || P->fwd3d || P->fwd4d) ) ||
+             ( P->inv || P->inv3d || P->inv4d) );
+}
 
 
 /* Move P to a new context - or to the default context if 0 is specified */
diff --git a/src/proj.def b/src/proj.def
index f758477d..6ab0c007 100644
--- a/src/proj.def
+++ b/src/proj.def
@@ -154,3 +154,4 @@ EXPORTS
 
     pj_approx_2D_trans             @138
     pj_approx_3D_trans             @139
+    pj_has_inverse                 @140
diff --git a/src/proj_4D_api.c b/src/proj_4D_api.c
index 4a416084..2c6bac2d 100644
--- a/src/proj_4D_api.c
+++ b/src/proj_4D_api.c
@@ -696,9 +696,7 @@ PJ_PROJ_INFO proj_pj_info(PJ *P) {
     pj_strlcpy(info.definition, &def[1], sizeof(info.definition)); /* def includes a leading space */
     pj_dealloc(def);
 
-    /* this does not take into account that a pipeline potentially does not */
-    /* have an inverse.                                                     */
-    info.has_inverse = (P->inv != 0 || P->inv3d != 0 || P->inv4d != 0);
+    info.has_inverse = pj_has_inverse(P);
 
     return info;
 }
diff --git a/src/proj_api.h b/src/proj_api.h
index 597a2589..40c40ad1 100644
--- a/src/proj_api.h
+++ b/src/proj_api.h
@@ -155,6 +155,7 @@ projPJ pj_init_ctx( projCtx, int, char ** );
 projPJ pj_init_plus_ctx( projCtx, const char * );
 char *pj_get_def(projPJ, int);
 projPJ pj_latlong_from_proj( projPJ );
+int pj_has_inverse(projPJ);
 
 
 void *pj_malloc(size_t);