This IExtension (TraceResultsRendererExt) is used to improve the performance of rendering trace results. To use this extension, first you will need to convert the EIDS from the results of the trace into two HashSets (one for edges and one for junctions) and then call SetSearchResults. Alternatively, you can call DisplayResults passing in the IEnumNetEID from a trace which calls SetSearchResults. SetSearchResults takes in addition to the two HashSets objects, the map point where the user initiated the trace, the start EID (perhaps found from the base tool that your trace tool inherits from), and the geometric network. This extension then registers a listener for the AfterDraw event and when that fires draws the result edges, junctions, and buffers to the screen in a manner that can be considerably more efficient than calling UtilityNetworkAnalyst:SetResults. User options such as the color of the results and the buffer are derived from the ArcFMTracingOptions form. That form is shared with the traces which also get properties from it that are used during the actual trace (e.g. PhasesToTraceOn).

'Declaration
 
<ComponentCategoryAttribute(Description="", CategoryID=b56a7c45-83d4-11d2-a2e9-080009b6f22b)>
<GuidAttribute("68b2bdea-5501-4db4-bb63-ade582399cb2")>
<ProgIdAttribute("TraceResultsRenderer.TraceResultsRendererExt")>
<ComVisibleAttribute(True)>
<ClassInterfaceAttribute(ClassInterfaceType.None)>
Public Class TraceResultsRendererExt 
   Implements ESRI.ArcGIS.esriSystem.IExtension, Miner.Interop.IMMTraceRenderer 

'Usage
 
Dim instance As TraceResultsRendererExt

[ComponentCategory(Description="", CategoryID=b56a7c45-83d4-11d2-a2e9-080009b6f22b)]
[Guid("68b2bdea-5501-4db4-bb63-ade582399cb2")]
[ProgId("TraceResultsRenderer.TraceResultsRendererExt")]
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
public class TraceResultsRendererExt : ESRI.ArcGIS.esriSystem.IExtension, Miner.Interop.IMMTraceRenderer