A serializer to the GraphViz DOT format.

This serializer has a set of associated serializer features that may be set to customise the output colors using raptor_serializer_set_feature() with the appropriate feature name and value as given below.

RAPTOR_FEATURE_RESOURCE_BORDER 	Border color of resource nodes
RAPTOR_FEATURE_LITERAL_BORDER 	Border color of literal nodes
RAPTOR_FEATURE_BNODE_BORDER 	Border color of blank nodes
RAPTOR_FEATURE_RESOURCE_FILL 	Fill color of resource nodes
RAPTOR_FEATURE_LITERAL_FILL 	Fill color of literal nodes
RAPTOR_FEATURE_BNODE_FILL 	Fill color of blank nodes