Fix most remaining methods which return a reference to

QgsCoordinateReferenceSystem or which take a pointer to a
CRS

doc/api_break.dox

@@ -18,6 +18,13 @@ This page tries to maintain a list with incompatible changes that happened in pr
 
 \section qgis_api_break_3_0 QGIS 3.0
 
+\subsection qgis_api_break_3_0_QgsCoordinateTransform QgsCoordinateTransform
+
+<ul>
+<li>sourceCrs() and destCrs() now return a copy instead of a reference to the CRS. This has no effect on PyQGIS code, but c++
+plugins calling these methods will need to be updated.</li>
+</ul>
+
 \subsection qgis_api_break_3_0_DataProviders Data Providers
 
 <ul>
@@ -47,6 +54,13 @@ only affects third party c++ providers, and does not affect PyQGIS scripts.</li>
 <li>crs() now returns a QgsCoordinateReferenceSystem object, not a reference. This change has no effect for PyQGIS code.</li>
 </ul>
 
+\subsection qgis_api_break_3_0_QgsJSONExporter QgsJSONExporter
+
+<ul>
+<li>sourceCrs() now returns a copy instead of a reference to the CRS. This has no effect on PyQGIS code, but c++
+plugins calling this method will need to be updated.</li>
+</ul>
+
 \subsection qgis_api_break_3_0_QgsVectorLayerImport QgsVectorLayerImport
 
 <ul>
@@ -56,6 +70,29 @@ pointers makes for more robust, safer code. Use an invalid (default constructed)
 in code which previously passed a null pointer to QgsVectorLayerImport.</li>
 </ul>
 
+\subsection qgis_api_break_3_0_QgsPointLocator QgsPointLocator
+
+<ul>
+<li>The constructor now takes a reference rather than a pointer to a CRS.  This has no effect on PyQGIS code, but c++
+plugins calling this method will need to be updated.</li>
+<li>destCrs() now returns a copy instead of a reference to the CRS. This has no effect on PyQGIS code, but c++
+plugins calling this method will need to be updated.</li>
+</ul>
+
+\subsection qgis_api_break_3_0_QgsMapSettings QgsMapSettings
+
+<ul>
+<li>destinationCrs() now returns a copy instead of a reference to the CRS. This has no effect on PyQGIS code, but c++
+plugins calling this method will need to be updated.</li>
+</ul>
+
+\subsection qgis_api_break_3_0_QgsGraphBuilderInterface QgsGraphBuilderInterface
+
+<ul>
+<li>destinationCrs() now returns a copy instead of a reference to the CRS. This has no effect on PyQGIS code, but c++
+plugins calling this method will need to be updated.</li>
+</ul>
+
 \subsection qgis_api_break_3_0_QgsVectorFileWriter QgsVectorFileWriter
 
 <ul>

python/analysis/network/qgsgraphbuilderintr.sip

@@ -30,7 +30,7 @@ class QgsGraphBuilderInterface
      */
     QgsGraphBuilderInterface( const QgsCoordinateReferenceSystem& crs, bool ctfEnabled = true, double topologyTolerance = 0.0, const QString& ellipsoidID = "WGS84" );
 
-    QgsCoordinateReferenceSystem& destinationCrs();
+    QgsCoordinateReferenceSystem destinationCrs() const;
 
     //! get coordinate transformation enabled
     bool coordinateTransformationEnabled();

python/core/qgscoordinatetransform.sip

@@ -79,13 +79,13 @@ class QgsCoordinateTransform : QObject
      * Get the QgsCoordinateReferenceSystem representation of the layer's coordinate system
      * @return QgsCoordinateReferenceSystem of the layer's coordinate system
      */
-    const QgsCoordinateReferenceSystem& sourceCrs() const;
+    QgsCoordinateReferenceSystem sourceCrs() const;
 
     /*!
      * Get the QgsCoordinateReferenceSystem representation of the map canvas coordinate system
      * @return QgsCoordinateReferenceSystem of the map canvas coordinate system
      */
-    const QgsCoordinateReferenceSystem& destCRS() const;
+    QgsCoordinateReferenceSystem destCRS() const;
 
     /** Transform the point from Source Coordinate System to Destination Coordinate System
      * If the direction is ForwardTransform then coordinates are transformed from layer CS --> map canvas CS,

python/core/qgsjsonutils.sip

@@ -90,7 +90,7 @@ class QgsJSONExporter
      * correctly automatically reprojected to WGS 84, to match GeoJSON specifications.
      * @see setSourceCrs()
      */
-    const QgsCoordinateReferenceSystem& sourceCrs() const;
+    QgsCoordinateReferenceSystem sourceCrs() const;
 
     /** Sets the list of attributes to include in the JSON exports.
      * @param attributes list of attribute indexes, or an empty list to include all

python/core/qgsmapsettings.sip

@@ -88,7 +88,7 @@ class QgsMapSettings
     //! sets destination coordinate reference system
     void setDestinationCrs( const QgsCoordinateReferenceSystem& crs );
     //! returns CRS of destination coordinate reference system
-    const QgsCoordinateReferenceSystem& destinationCrs() const;
+    QgsCoordinateReferenceSystem destinationCrs() const;
 
     //! Get units of map's geographical coordinates - used for scale calculation
     QGis::UnitType mapUnits() const;

python/core/qgspointlocator.sip

@@ -19,20 +19,23 @@ class QgsPointLocator : QObject
 %End
 
   public:
+
     /** Construct point locator for a layer.
-     *  @arg destCRS if not null, will do the searches on data reprojected to the given CRS
+     *  @arg destCRS if a valid QgsCoordinateReferenceSystem is passed then the locator will
+     *  do the searches on data reprojected to the given CRS
      *  @arg extent  if not null, will index only a subset of the layer
      */
-    explicit QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateReferenceSystem* destCRS = 0, const QgsRectangle* extent = 0 );
+    explicit QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateReferenceSystem& destCRS = QgsCoordinateReferenceSystem(),
+                              const QgsRectangle* extent = nullptr );
 
     ~QgsPointLocator();
 
     //! Get associated layer
     //! @note added in QGIS 2.14
     QgsVectorLayer* layer() const;
-    //! Get destination CRS - may be null if not doing OTF reprojection
+    //! Get destination CRS - may be an invalid QgsCoordinateReferenceSystem if not doing OTF reprojection
     //! @note added in QGIS 2.14
-    const QgsCoordinateReferenceSystem* destCRS() const;
+    QgsCoordinateReferenceSystem destCRS() const;
     //! Get extent of the area point locator covers - if null then it caches the whole layer
     //! @note added in QGIS 2.14
     const QgsRectangle* extent() const;

src/analysis/network/qgsgraphbuilderintr.h

@@ -56,7 +56,7 @@ class ANALYSIS_EXPORT QgsGraphBuilderInterface
     { }
 
     //! get destinaltion Crs
-    QgsCoordinateReferenceSystem& destinationCrs()
+    QgsCoordinateReferenceSystem destinationCrs() const
     {
       return mCrs;
     }

src/app/qgsdecorationgrid.cpp

@@ -833,7 +833,7 @@ bool QgsDecorationGrid::getIntervalFromCurrentLayer( double* values )
     return false;
   }
   QgsCoordinateReferenceSystem layerCRS = layer->crs();
-  const QgsCoordinateReferenceSystem& mapCRS =
+  QgsCoordinateReferenceSystem mapCRS =
     QgisApp::instance()->mapCanvas()->mapSettings().destinationCrs();
   // is this the best way to compare CRS? should we also make sure map has OTF enabled?
   // TODO calculate transformed values if necessary

src/app/qgsidentifyresultsdialog.h

@@ -68,7 +68,7 @@ class APP_EXPORT QgsIdentifyResultsFeatureItem: public QTreeWidgetItem
     QgsIdentifyResultsFeatureItem( const QgsFields &fields, const QgsFeature &feature, const QgsCoordinateReferenceSystem &crs, const QStringList & strings = QStringList() );
     const QgsFields &fields() const { return mFields; }
     const QgsFeature &feature() const { return mFeature; }
-    const QgsCoordinateReferenceSystem &crs() { return mCrs; }
+    QgsCoordinateReferenceSystem crs() const { return mCrs; }
 
   private:
     QgsFields mFields;

src/core/qgscoordinatetransform.h

@@ -113,13 +113,13 @@ class CORE_EXPORT QgsCoordinateTransform : public QObject
      * Get the QgsCoordinateReferenceSystem representation of the layer's coordinate system
      * @return QgsCoordinateReferenceSystem of the layer's coordinate system
      */
-    const QgsCoordinateReferenceSystem& sourceCrs() const { return mSourceCRS; }
+    QgsCoordinateReferenceSystem sourceCrs() const { return mSourceCRS; }
 
     /*!
      * Get the QgsCoordinateReferenceSystem representation of the map canvas coordinate system
      * @return QgsCoordinateReferenceSystem of the map canvas coordinate system
      */
-    const QgsCoordinateReferenceSystem& destCRS() const { return mDestCRS; }
+    QgsCoordinateReferenceSystem destCRS() const { return mDestCRS; }
 
     /** Transform the point from Source Coordinate System to Destination Coordinate System
      * If the direction is ForwardTransform then coordinates are transformed from layer CS --> map canvas CS,

src/core/qgsjsonutils.cpp

@@ -58,7 +58,7 @@ void QgsJSONExporter::setSourceCrs( const QgsCoordinateReferenceSystem& crs )
   mTransform.setSourceCrs( mCrs );
 }
 
-const QgsCoordinateReferenceSystem& QgsJSONExporter::sourceCrs() const
+QgsCoordinateReferenceSystem QgsJSONExporter::sourceCrs() const
 {
   return mCrs;
 }

src/core/qgsjsonutils.h

@@ -112,7 +112,7 @@ class CORE_EXPORT QgsJSONExporter
      * correctly automatically reprojected to WGS 84, to match GeoJSON specifications.
      * @see setSourceCrs()
      */
-    const QgsCoordinateReferenceSystem& sourceCrs() const;
+    QgsCoordinateReferenceSystem sourceCrs() const;
 
     /** Sets the list of attributes to include in the JSON exports.
      * @param attributes list of attribute indexes, or an empty list to include all

src/core/qgsmapsettings.cpp

@@ -291,7 +291,7 @@ void QgsMapSettings::setDestinationCrs( const QgsCoordinateReferenceSystem& crs
   mDatumTransformStore.setDestinationCrs( crs );
 }
 
-const QgsCoordinateReferenceSystem& QgsMapSettings::destinationCrs() const
+QgsCoordinateReferenceSystem QgsMapSettings::destinationCrs() const
 {
   return mDestCRS;
 }

src/core/qgsmapsettings.h

@@ -136,7 +136,7 @@ class CORE_EXPORT QgsMapSettings
     //! sets destination coordinate reference system
     void setDestinationCrs( const QgsCoordinateReferenceSystem& crs );
     //! returns CRS of destination coordinate reference system
-    const QgsCoordinateReferenceSystem& destinationCrs() const;
+    QgsCoordinateReferenceSystem destinationCrs() const;
 
     //! Get units of map's geographical coordinates - used for scale calculation
     QGis::UnitType mapUnits() const;

src/core/qgspointlocator.cpp

@@ -608,7 +608,7 @@ class QgsPointLocator_DumpTree : public SpatialIndex::IQueryStrategy
 ////////////////////////////////////////////////////////////////////////////
 
 
-QgsPointLocator::QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateReferenceSystem* destCRS, const QgsRectangle* extent )
+QgsPointLocator::QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateReferenceSystem& destCRS, const QgsRectangle* extent )
     : mStorage( nullptr )
     , mRTree( nullptr )
     , mIsEmptyLayer( false )
@@ -616,9 +616,9 @@ QgsPointLocator::QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateRefe
     , mLayer( layer )
     , mExtent( nullptr )
 {
-  if ( destCRS )
+  if ( destCRS.isValid() )
   {
-    mTransform = new QgsCoordinateTransform( layer->crs(), *destCRS );
+    mTransform = new QgsCoordinateTransform( layer->crs(), destCRS );
   }
 
   setExtent( extent );
@@ -639,9 +639,9 @@ QgsPointLocator::~QgsPointLocator()
   delete mExtent;
 }
 
-const QgsCoordinateReferenceSystem* QgsPointLocator::destCRS() const
+QgsCoordinateReferenceSystem QgsPointLocator::destCRS() const
 {
-  return mTransform ? &mTransform->destCRS() : nullptr;
+  return mTransform ? mTransform->destCRS() : QgsCoordinateReferenceSystem();
 }
 
 void QgsPointLocator::setExtent( const QgsRectangle* extent )

src/core/qgspointlocator.h

@@ -22,9 +22,9 @@ class QgsVectorLayer;
 #include "qgsfeature.h"
 #include "qgspoint.h"
 #include "qgsrectangle.h"
+#include "qgscoordinatereferencesystem.h"
 
 class QgsCoordinateTransform;
-class QgsCoordinateReferenceSystem;
 
 class QgsPointLocator_VisitorNearestVertex;
 class QgsPointLocator_VisitorNearestEdge;
@@ -52,19 +52,21 @@ class CORE_EXPORT QgsPointLocator : public QObject
     Q_OBJECT
   public:
     /** Construct point locator for a layer.
-     *  @arg destCRS if not null, will do the searches on data reprojected to the given CRS
+     *  @arg destCRS if a valid QgsCoordinateReferenceSystem is passed then the locator will
+     *  do the searches on data reprojected to the given CRS
      *  @arg extent  if not null, will index only a subset of the layer
      */
-    explicit QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateReferenceSystem* destCRS = nullptr, const QgsRectangle* extent = nullptr );
+    explicit QgsPointLocator( QgsVectorLayer* layer, const QgsCoordinateReferenceSystem& destCRS = QgsCoordinateReferenceSystem(),
+                              const QgsRectangle* extent = nullptr );
 
     ~QgsPointLocator();
 
     //! Get associated layer
     //! @note added in QGIS 2.14
     QgsVectorLayer* layer() const { return mLayer; }
-    //! Get destination CRS - may be null if not doing OTF reprojection
+    //! Get destination CRS - may be an invalid QgsCoordinateReferenceSystem if not doing OTF reprojection
     //! @note added in QGIS 2.14
-    const QgsCoordinateReferenceSystem* destCRS() const;
+    QgsCoordinateReferenceSystem destCRS() const;
     //! Get extent of the area point locator covers - if null then it caches the whole layer
     //! @note added in QGIS 2.14
     const QgsRectangle* extent() const { return mExtent; }

src/core/qgssnappingutils.cpp

@@ -572,9 +572,9 @@ QString QgsSnappingUtils::dump()
   return msg;
 }
 
-const QgsCoordinateReferenceSystem* QgsSnappingUtils::destCRS()
+QgsCoordinateReferenceSystem QgsSnappingUtils::destCRS() const
 {
-  return mMapSettings.hasCrsTransformEnabled() ? &mMapSettings.destinationCrs() : nullptr;
+  return mMapSettings.hasCrsTransformEnabled() ? mMapSettings.destinationCrs() : QgsCoordinateReferenceSystem();
 }
 
 

src/core/qgssnappingutils.h

@@ -185,8 +185,8 @@ class CORE_EXPORT QgsSnappingUtils : public QObject
     void onLayersWillBeRemoved( const QStringList& layerIds );
 
   private:
-    //! get from map settings pointer to destination CRS - or 0 if projections are disabled
-    const QgsCoordinateReferenceSystem* destCRS();
+    //! Get destination CRS from map settings, or an invalid CRS if projections are disabled
+    QgsCoordinateReferenceSystem destCRS() const;
 
     //! delete all existing locators (e.g. when destination CRS has changed and we need to reindex)
     void clearAllLocators();

src/server/qgsserverprojectparser.cpp

@@ -747,7 +747,7 @@ void QgsServerProjectParser::combineExtentAndCrsOfGroupChildren( QDomElement& gr
 
   QgsConfigParserUtils::appendCRSElementsToLayer( groupElem, doc, combinedCRSSet.toList(), supportedOutputCrsList() );
 
-  const QgsCoordinateReferenceSystem& groupCRS = projectCRS();
+  QgsCoordinateReferenceSystem groupCRS = projectCRS();
   if ( considerMapExtent )
   {
     QgsRectangle mapRect = mapRectangle();
@@ -879,7 +879,7 @@ QgsRectangle QgsServerProjectParser::layerBoundingBoxInProjectCRS( const QDomEle
   }
 
   //get project crs
-  const QgsCoordinateReferenceSystem& projectCrs = projectCRS();
+  QgsCoordinateReferenceSystem projectCrs = projectCRS();
   QgsCoordinateTransform t( layerCrs, projectCrs );
 
   //transform