Disallow use of non-projection operations in proj

Since the introduction of other operations types than projections it has
been unclear how proj should treat those. This commit sets record
straight once and for all: proj is only allowed to initialize operations
that take angular input and produces non-angular output, i.e.
projections. This is true to the version of proj before the introduction
of the pipeline and other non-projection operations. Users can still
initiliaze pipelines with proj as long as the resulting concatenated
operation requires angular input and outputs non-angular output.

1 files changed, 10 insertions, 12 deletions

diff --git a/src/proj.c b/src/proj.c
index e01175a5..293193e7 100644
--- a/src/proj.c
+++ b/src/proj.c
@@ -160,12 +160,12 @@ static void process(FILE *fid) {
             }
         } else {    /* x-y or decimal degree ascii output, scale if warranted by output units */
             if (inverse) {
-                if (Proj->left == PJ_IO_UNITS_ANGULAR) {
+                if (proj_angular_input(Proj, PJ_FWD)) {
                     data.uv.v *= RAD_TO_DEG;
                     data.uv.u *= RAD_TO_DEG;
                 }
             } else {
-                if (Proj->right == PJ_IO_UNITS_ANGULAR) {
+                if (proj_angular_output(Proj, PJ_FWD)) {
                     data.uv.v *= RAD_TO_DEG;
                     data.uv.u *= RAD_TO_DEG;
                 }
@@ -268,12 +268,6 @@ static void vprocess(FILE *fid) {
             if (postscale) { dat_xy.x *= fscale; dat_xy.y *= fscale; }
         }
 
-        /* apply rad->deg scaling in case the output from a pipeline has degrees as units */
-        if (!inverse && Proj->right == PJ_IO_UNITS_ANGULAR) {
-            dat_xy.x *= RAD_TO_DEG;
-            dat_xy.y *= RAD_TO_DEG;
-        }
-
         /* For some reason pj_errno does not work as expected in some   */
         /* versions of Visual Studio, so using pj_get_errno_ref instead */
         if (*pj_get_errno_ref()) {
@@ -501,10 +495,14 @@ int main(int argc, char **argv) {
         emess(3,"projection initialization failure\ncause: %s",
               pj_strerrno(pj_errno));
 
-    if( pj_is_latlong( Proj ) )
-    {
-        emess( 3, "+proj=latlong unsuitable for use with proj program." );
-        exit( 0 );
+    if (!proj_angular_input(Proj, PJ_FWD)) {
+        emess(3, "can't initialize operations that take angular input coordinates");
+        exit(0);
+    }
+
+    if (proj_angular_output(Proj, PJ_FWD)) {
+        emess(3, "can't initialize operations that produce angular output coordinates");
+        exit(0);
     }
 
     if (inverse) {