Mark some inbuilt expression variables with missing read-only flag

Author: nyalldawson

src/core/qgsexpressioncontext.cpp

@@ -429,7 +429,8 @@ void QgsExpressionContext::setOriginalValueVariable( const QVariant &value )
   if ( mStack.isEmpty() )
     mStack.append( new QgsExpressionContextScope() );
 
-  mStack.last()->setVariable( QgsExpressionContext::EXPR_ORIGINAL_VALUE, value );
+  mStack.last()->addVariable( QgsExpressionContextScope::StaticVariable( QgsExpressionContext::EXPR_ORIGINAL_VALUE,
+                              value, true ) );
 }
 
 
@@ -711,8 +712,8 @@ QgsExpressionContextScope* QgsExpressionContextUtils::mapSettingsScope( const Qg
   scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_id", "canvas", true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_rotation", mapSettings.rotation(), true ) );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_scale", mapSettings.scale(), true ) );
-  scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_extent_width", mapSettings.extent().width() ) );
-  scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_extent_height", mapSettings.extent().height() ) );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_extent_width", mapSettings.extent().width(), true ) );
+  scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_extent_height", mapSettings.extent().height(), true ) );
   QgsGeometry* centerPoint = QgsGeometry::fromPoint( mapSettings.visibleExtent().center() );
   scope->addVariable( QgsExpressionContextScope::StaticVariable( "map_extent_center", QVariant::fromValue( *centerPoint ), true ) );
   delete centerPoint;