Notify about QgsProject::crs changes

Author: m-kuhn

python/core/qgsproject.sip

@@ -546,6 +546,8 @@ class QgsProject : QObject, QgsExpressionContextGenerator
      */
     void customVariablesChanged();
 
+    void crsChanged();
+
     /**
      * Emitted whenever a new transaction group has been created or a
      * transaction group has been removed.

src/core/qgsproject.cpp

@@ -433,6 +433,8 @@ void QgsProject::setCrs( const QgsCoordinateReferenceSystem &crs )
   writeEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCRSID" ), static_cast< int >( crs.srsid() ) );
   writeEntry( QStringLiteral( "SpatialRefSys" ), QStringLiteral( "/ProjectCrs" ), crs.authid() );
   setDirty( true );
+
+  emit crsChanged();
 }
 
 QString QgsProject::ellipsoid() const
@@ -929,6 +931,7 @@ bool QgsProject::read()
     setDirty( false );
 
   emit nonIdentifiableLayersChanged( nonIdentifiableLayers() );
+  emit crsChanged();
 
   return true;
 }

src/core/qgsproject.h

@@ -77,7 +77,7 @@ class CORE_EXPORT QgsProject : public QObject, public QgsExpressionContextGenera
     Q_PROPERTY( QStringList nonIdentifiableLayers READ nonIdentifiableLayers WRITE setNonIdentifiableLayers NOTIFY nonIdentifiableLayersChanged )
     Q_PROPERTY( QString fileName READ fileName WRITE setFileName NOTIFY fileNameChanged )
     Q_PROPERTY( QString homePath READ homePath NOTIFY homePathChanged )
-    Q_PROPERTY( QgsCoordinateReferenceSystem crs READ crs WRITE setCrs )
+    Q_PROPERTY( QgsCoordinateReferenceSystem crs READ crs WRITE setCrs NOTIFY crsChanged )
     Q_PROPERTY( QgsMapThemeCollection *mapThemeCollection READ mapThemeCollection NOTIFY mapThemeCollectionChanged )
     Q_PROPERTY( QgsSnappingConfig snappingConfig READ snappingConfig WRITE setSnappingConfig NOTIFY snappingConfigChanged )
     Q_PROPERTY( QgsRelationManager *relationManager READ relationManager )
@@ -749,6 +749,13 @@ class CORE_EXPORT QgsProject : public QObject, public QgsExpressionContextGenera
      */
     void customVariablesChanged();
 
+    /**
+     * Emitted when the CRS of the project has changed.
+     *
+     * @note Added in QGIS 3.0
+     */
+    void crsChanged();
+
     /**
      * Emitted whenever a new transaction group has been created or a
      * transaction group has been removed.