From e8c94112b37579fbd70897363aaea065d5317a7c Mon Sep 17 00:00:00 2001
From: Sandro Santilli <strk@kbt.io>
Date: Mon, 16 Nov 2020 11:59:46 +0100
Subject: [PATCH] Use GEOSPreparedDistance when available

Allow speeding up GEOSDistance computation.
See
https://github.com/qgis/QGIS/pull/39970#pullrequestreview-528643769

Requires GEOS-3.9+

Also fixes a conditional about GEOS for nearestPoints
---
 src/core/geometry/qgsgeos.cpp | 11 +++++++++++
 src/core/pal/pointset.cpp     |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/core/geometry/qgsgeos.cpp b/src/core/geometry/qgsgeos.cpp
index fd1bb3a6c4d2..47025feb290a 100644
--- a/src/core/geometry/qgsgeos.cpp
+++ b/src/core/geometry/qgsgeos.cpp
@@ -430,7 +430,18 @@ double QgsGeos::distance( const QgsAbstractGeometry *geom, QString *errorMsg ) c
 
   try
   {
+#if GEOS_VERSION_MAJOR>3 || ( GEOS_VERSION_MAJOR == 3 && GEOS_VERSION_MINOR>=9 )
+    if ( mGeosPrepared )
+    {
+      GEOSPreparedDistance_r( geosinit()->ctxt, mGeosPrepared.get(), otherGeosGeom.get(), &distance );
+    }
+    else
+    {
+      GEOSDistance_r( geosinit()->ctxt, mGeos.get(), otherGeosGeom.get(), &distance );
+    }
+#else
     GEOSDistance_r( geosinit()->ctxt, mGeos.get(), otherGeosGeom.get(), &distance );
+#endif
   }
   CATCH_GEOS_WITH_ERRMSG( -1.0 )
 
diff --git a/src/core/pal/pointset.cpp b/src/core/pal/pointset.cpp
index a67125486ce1..376ae29089e2 100644
--- a/src/core/pal/pointset.cpp
+++ b/src/core/pal/pointset.cpp
@@ -842,7 +842,7 @@ double PointSet::minDistanceToPoint( double px, double py, double *rx, double *r
 #endif
     }
 
-#if GEOS_VERSION_MAJOR>3 || GEOS_VERSION_MINOR>=9
+#if GEOS_VERSION_MAJOR>3 || ( GEOS_VERSION_MAJOR == 3 && GEOS_VERSION_MINOR>=9 )
     geos::coord_sequence_unique_ptr nearestCoord( GEOSPreparedNearestPoints_r( geosctxt, preparedExtRing, geosPt.get() ) );
 #else
     geos::coord_sequence_unique_ptr nearestCoord( GEOSNearestPoints_r( geosctxt, extRing, geosPt.get() ) );