Use unique_ptrs for proj object storage

Sponsored by ICSM

Author: nyalldawson

python/core/auto_generated/qgsprojutils.sip.in

@@ -10,6 +10,7 @@
 
 
 
+
 class QgsProjUtils
 {
 %Docstring
@@ -27,6 +28,7 @@ Utility functions for working with the proj library.
 %Docstring
 Returns the proj library major version number.
 %End
+
 };
 
 /************************************************************************

src/core/qgscoordinatetransform.cpp

@@ -691,8 +691,8 @@ void QgsCoordinateTransform::transformCoords( int numPoints, double *x, double *
     QString dir = ( direction == ForwardTransform ) ? QObject::tr( "forward transform" ) : QObject::tr( "inverse transform" );
 
 #if PROJ_VERSION_MAJOR>=6
-    PJ *src = proj_get_source_crs( QgsProjContext::get(), projData );
-    PJ *dest = proj_get_source_crs( QgsProjContext::get(), projData );
+    QgsProjUtils::proj_pj_unique_ptr src( proj_get_source_crs( QgsProjContext::get(), projData ) );
+    QgsProjUtils::proj_pj_unique_ptr dest( proj_get_source_crs( QgsProjContext::get(), projData ) );
     QString msg = QObject::tr( "%1 of\n"
                                "%2"
                                "PROJ: %3\n"
@@ -701,8 +701,6 @@ void QgsCoordinateTransform::transformCoords( int numPoints, double *x, double *
                         points,
                         proj_as_proj_string( QgsProjContext::get(), projData, PJ_PROJ_5, nullptr ),
                         QString::fromUtf8( proj_errno_string( projResult ) ) );
-    proj_destroy( src );
-    proj_destroy( dest );
 #else
     char *srcdef = pj_get_def( sourceProj, 0 );
     char *dstdef = pj_get_def( destProj, 0 );

src/core/qgsellipsoidutils.cpp

@@ -359,17 +359,18 @@ QList<QgsEllipsoidUtils::EllipsoidDefinition> QgsEllipsoidUtils::definitions()
         PROJ_STRING_LIST codesIt = codes;
         while ( char *code = *codesIt )
         {
-          if ( PJ *ellipsoid = proj_create_from_database( context, authority, code, PJ_CATEGORY_ELLIPSOID, 0, nullptr ) )
+          QgsProjUtils::proj_pj_unique_ptr ellipsoid( proj_create_from_database( context, authority, code, PJ_CATEGORY_ELLIPSOID, 0, nullptr ) );
+          if ( ellipsoid.get() )
           {
             EllipsoidDefinition def;
-            QString name = QString( proj_get_name( ellipsoid ) );
+            QString name = QString( proj_get_name( ellipsoid.get() ) );
             def.acronym = QStringLiteral( "%1:%2" ).arg( authority, code );
             name.replace( '_', ' ' );
             def.description = QStringLiteral( "%1 (%2:%3)" ).arg( name, authority, code );
 
             double semiMajor, semiMinor, invFlattening;
             int semiMinorComputed = 0;
-            if ( proj_ellipsoid_get_parameters( context, ellipsoid, &semiMajor, &semiMinor, &semiMinorComputed, &invFlattening ) )
+            if ( proj_ellipsoid_get_parameters( context, ellipsoid.get(), &semiMajor, &semiMinor, &semiMinorComputed, &invFlattening ) )
             {
               def.parameters.semiMajor = semiMajor;
               def.parameters.semiMinor = semiMinor;
@@ -386,8 +387,6 @@ QList<QgsEllipsoidUtils::EllipsoidDefinition> QgsEllipsoidUtils::definitions()
               def.parameters.valid = false;
             }
 
-            proj_destroy( ellipsoid );
-
             defs << def;
             sEllipsoidCache.insert( def.acronym, def.parameters );
           }

src/core/qgsprojutils.cpp

@@ -65,3 +65,10 @@ PJ_CONTEXT *QgsProjContext::get()
   return pContext;
 #endif
 }
+
+#if PROJ_VERSION_MAJOR>=6
+void QgsProjUtils::ProjPJDeleter::operator()( PJ *object )
+{
+  proj_destroy( object );
+}
+#endif

src/core/qgsprojutils.h

@@ -21,11 +21,19 @@
 
 #include "qgis_core.h"
 #include "qgsconfig.h"
+#include <memory>
 
 #if !defined(USE_THREAD_LOCAL) || defined(Q_OS_WIN)
 #include <QThreadStorage>
 #endif
 
+#if PROJ_VERSION_MAJOR>=6
+#ifndef SIP_RUN
+struct PJconsts;
+typedef struct PJconsts PJ;
+#endif
+#endif
+
 /**
  * \class QgsProjUtils
  * \ingroup core
@@ -43,6 +51,30 @@ class CORE_EXPORT QgsProjUtils
     {
       return PROJ_VERSION_MAJOR;
     }
+
+#ifndef SIP_RUN
+#if PROJ_VERSION_MAJOR >= 6
+
+    /**
+     * Destroys Proj PJ objects.
+     */
+    struct ProjPJDeleter
+    {
+
+      /**
+       * Destroys an PJ \a object, using the correct proj calls.
+       */
+      void CORE_EXPORT operator()( PJ *object );
+
+    };
+
+    /**
+     * Scoped Proj PJ object.
+     */
+    using proj_pj_unique_ptr = std::unique_ptr< PJ, ProjPJDeleter >;
+
+#endif
+#endif
 };
 
 #ifndef SIP_RUN