Add proj_get_suggested_operation()

Return the index of the operation that would be the most appropriate to
transform the specified coordinates.

This operation may use resources that are not locally available, depending
on the search criteria used by proj_create_operations().

This could be done by using proj_create_operations() with a punctual bounding
box, but this function is faster when one needs to evaluate on many points
with the same (source_crs, target_crs) tuple.

1 files changed, 59 insertions, 46 deletions

diff --git a/src/proj_internal.h b/src/proj_internal.h
index 8f73200d..f3e1e2e8 100644
--- a/src/proj_internal.h
+++ b/src/proj_internal.h
@@ -287,6 +287,55 @@ typedef    PJ_COORD  (* PJ_OPERATOR)    (PJ_COORD, PJ *);
 #define PJD_GRIDSHIFT 3
 #define PJD_WGS84     4   /* WGS84 (or anything considered equivalent) */
 
+struct CoordOperation
+{
+    int idxInOriginalList;
+    double minxSrc = 0.0;
+    double minySrc = 0.0;
+    double maxxSrc = 0.0;
+    double maxySrc = 0.0;
+    double minxDst = 0.0;
+    double minyDst = 0.0;
+    double maxxDst = 0.0;
+    double maxyDst = 0.0;
+    PJ* pj = nullptr;
+    std::string name{};
+    double accuracy = -1.0;
+    bool isOffshore = false;
+
+    CoordOperation(int idxInOriginalListIn,
+                   double minxSrcIn, double minySrcIn, double maxxSrcIn, double maxySrcIn,
+                   double minxDstIn, double minyDstIn, double maxxDstIn, double maxyDstIn,
+                   PJ* pjIn, const std::string& nameIn, double accuracyIn, bool isOffshoreIn):
+        idxInOriginalList(idxInOriginalListIn),
+        minxSrc(minxSrcIn), minySrc(minySrcIn), maxxSrc(maxxSrcIn), maxySrc(maxySrcIn),
+        minxDst(minxDstIn), minyDst(minyDstIn), maxxDst(maxxDstIn), maxyDst(maxyDstIn),
+        pj(pjIn), name(nameIn),
+        accuracy(accuracyIn),
+        isOffshore(isOffshoreIn)
+    {
+    }
+
+    CoordOperation(const CoordOperation&) = delete;
+
+    CoordOperation(CoordOperation&& other):
+        idxInOriginalList(other.idxInOriginalList),
+        minxSrc(other.minxSrc), minySrc(other.minySrc), maxxSrc(other.maxxSrc), maxySrc(other.maxySrc),
+        minxDst(other.minxDst), minyDst(other.minyDst), maxxDst(other.maxxDst), maxyDst(other.maxyDst),
+        name(std::move(other.name)),
+        accuracy(other.accuracy),
+        isOffshore(other.isOffshore) {
+        pj = other.pj;
+        other.pj = nullptr;
+    }
+
+    CoordOperation& operator=(const CoordOperation&) = delete;
+
+    ~CoordOperation()
+    {
+        proj_destroy(pj);
+    }
+};
 
 /* base projection data structure */
 struct PJconsts {
@@ -493,52 +542,6 @@ struct PJconsts {
     /*************************************************************************************
      proj_create_crs_to_crs() alternative coordinate operations
     **************************************************************************************/
-
-    struct CoordOperation
-    {
-        double minxSrc = 0.0;
-        double minySrc = 0.0;
-        double maxxSrc = 0.0;
-        double maxySrc = 0.0;
-        double minxDst = 0.0;
-        double minyDst = 0.0;
-        double maxxDst = 0.0;
-        double maxyDst = 0.0;
-        PJ* pj = nullptr;
-        std::string name{};
-        double accuracy = -1.0;
-        bool isOffshore = false;
-
-        CoordOperation(double minxSrcIn, double minySrcIn, double maxxSrcIn, double maxySrcIn,
-                       double minxDstIn, double minyDstIn, double maxxDstIn, double maxyDstIn,
-                       PJ* pjIn, const std::string& nameIn, double accuracyIn, bool isOffshoreIn):
-            minxSrc(minxSrcIn), minySrc(minySrcIn), maxxSrc(maxxSrcIn), maxySrc(maxySrcIn),
-            minxDst(minxDstIn), minyDst(minyDstIn), maxxDst(maxxDstIn), maxyDst(maxyDstIn),
-            pj(pjIn), name(nameIn),
-            accuracy(accuracyIn),
-            isOffshore(isOffshoreIn)
-        {
-        }
-
-        CoordOperation(const CoordOperation&) = delete;
-
-        CoordOperation(CoordOperation&& other):
-            minxSrc(other.minxSrc), minySrc(other.minySrc), maxxSrc(other.maxxSrc), maxySrc(other.maxySrc),
-            minxDst(other.minxDst), minyDst(other.minyDst), maxxDst(other.maxxDst), maxyDst(other.maxyDst),
-            name(std::move(other.name)),
-            accuracy(other.accuracy),
-            isOffshore(other.isOffshore) {
-            pj = other.pj;
-            other.pj = nullptr;
-        }
-
-        CoordOperation& operator=(const CoordOperation&) = delete;
-
-        ~CoordOperation()
-        {
-            proj_destroy(pj);
-        }
-    };
     std::vector<CoordOperation> alternativeCoordinateOperations{};
     int iCurCoordOp = -1;
 
@@ -873,6 +876,16 @@ std::string PROJ_DLL pj_context_get_user_writable_directory(PJ_CONTEXT *ctx, boo
 void PROJ_DLL pj_context_set_user_writable_directory(PJ_CONTEXT* ctx, const std::string& path);
 std::string PROJ_DLL pj_get_relative_share_proj(PJ_CONTEXT *ctx);
 
+std::vector<CoordOperation> pj_create_prepared_operations(PJ_CONTEXT *ctx,
+                                                     const PJ *source_crs,
+                                                     const PJ *target_crs,
+                                                     PJ_OBJ_LIST* op_list);
+int pj_get_suggested_operation(PJ_CONTEXT *ctx,
+                               const std::vector<CoordOperation>& opList,
+                               const int iExcluded[2],
+                               PJ_DIRECTION direction,
+                               PJ_COORD coord);
+
 /* classic public API */
 #include "proj_api.h"