编辑时snapping的添加

IMapControl3 mMap = (IMapControl3)((IToolbarControl)toolHook).Buddy;
IEngineEditor m_engineEditor = new EngineEditorClass();
if (m_engineEditor.EditState == esriEngineEditState.esriEngineStateNotEditing)
{
//Start editing the workspace of the first feature layer found.        
ILayer currentLayer = mMap.get_Layer(0);
if (currentLayer is IFeatureLayer)
{
    IFeatureLayer featureLayer = currentLayer as IFeatureLayer;
    IDataset dataset = featureLayer.FeatureClass as IDataset;
    IWorkspace workspace = dataset.Workspace;
    m_engineEditor.StartEditing(workspace, mMap.Map);
    ((IEngineEditLayers)m_engineEditor).SetTargetLayer(featureLayer, 0);
}
//snapping
if (mMap.LayerCount != 0)
{
    IEngineEditor editor = new EngineEditorClass();
    IEngineEditLayers editLayers = editor as IEngineEditLayers;
    IEngineSnapEnvironment snapEnvironment = editor as IEngineSnapEnvironment;

    IEngineFeatureSnapAgent featureSnapAgent = new EngineFeatureSnap();
    featureSnapAgent.FeatureClass = ((IFeatureLayer)mMap.get_Layer(0)).FeatureClass; ;
    featureSnapAgent.HitType = esriGeometryHitPartType.esriGeometryPartVertex | esriGeometryHitPartType.esriGeometryPartBoundary | esriGeometryHitPartType.esriGeometryPartEndpoint;
    snapEnvironment.AddSnapAgent(featureSnapAgent);    
}