ArcObjects Library Reference (Carto)  

ILookupSymbol Interface

Provides access to functionality for looking up a renderer's symbol via a feature.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

Members

Description
Method LookupSymbol Returns a reference to the renderer's symbol for the input feature.
Method ResetLookupSymbol Resets temporary options on the symbol (e.g. Rotation).

CoClasses that implement ILookupSymbol

CoClasses and Classes Description
ClassBreaksRenderer A renderer that can be used to draw graduated color (choropleth) and graduated symbol maps.
CoTrackSymbologyRenderer (esriTrackingAnalyst) Symbolizes temporal based features and tracks in order to identify temporal feature characteristics in relation to the temporal reference.
RepresentationRenderer A renderer that draws features using representation information stored in the layers data source.
SimpleRenderer A simple renderer where the same symbol is drawn for each feature.
UniqueValueRenderer A unique values renderer where symbols are assigned to features based on an unique attribute values.

Remarks

I LookupSymbol is used as a faster alternative to IFeatureRenderer::SymbolByFeature when querying for a features symbol during labeling.  While SymbolByFeature hands out clones of a symbol, ISymbolLookup provides a framework where references to symbols are handed out and modifications of the symbol are reset.  Your renderer should implement this interface to make labeling perform efficiently.