Classes that show up as Element have no specific API functionality beyond element.
As the location of the element it not exposed nor is the geometry you have two options:
Centre of BoundingBox or Implement IExportContext2D and gather the geometry via that. I would do the latter as it gives you more control.
1) Use OnElementBegin2D to check the id against the element you want to look at then pass Skip or Proceed depending on if your id matches
2) OnCurve will give you details of curves (called for each).
3) OnText will give you details of text*. Note that this will happen regardless of what you set for RenderNodeAction in OnElementBegin2D. The best way to avoid calling it for text elements you are not interested in is to do as follows:
During OnElementBegin2d store the ElemendId as a variable
During OnElementEnd2d set the ElementId variable to ElementId.InvalidElementId
During OnText exit the sub if variable is not set to Elementid.InvalidElementId
*To export text you need to set CustomExporter.Export2DIncludingAnnotationObjects to true
I'm finding the best approach is to implement IExportContext2D via a general class and then inherit that. This then avoids having to implement all the members each time and you can build in some filtering similar to above:
Imports Autodesk.Revit.DB
Public Class RT_ExportContext2d_Limited
Implements IExportContext2D
Private IntDoc As Document = Nothing
Private FilterEIDs As List(Of ElementId) = Nothing
Private IntCurrentEID As ElementId = ElementId.InvalidElementId
Public Property DefaultAction As RenderNodeAction = RenderNodeAction.Proceed
Public Sub New(D As Document, Optional TargetElementIds As List(Of ElementId) = Nothing)
FilterEIDs = TargetElementIds
IntDoc = D
End Sub
Public Overridable Function Start() As Boolean Implements IExportContext.Start
Return True
End Function
Public Overridable Sub Finish() Implements IExportContext.Finish
End Sub
Public Overridable Function IsCanceled() As Boolean Implements IExportContext.IsCanceled
Return False
End Function
#Region "OnBegins"
Public Overridable Function OnViewBegin(node As ViewNode) As RenderNodeAction Implements IExportContext.OnViewBegin
Return DefaultAction
End Function
Public Function OnElementBegin2D(node As ElementNode) As RenderNodeAction Implements IExportContext2D.OnElementBegin2D
IntCurrentEID = node.ElementId
If FilterEIDs IsNot Nothing Then
If FilterEIDs.Contains(node.ElementId) Then
Return RenderNodeAction.Proceed
Else
Return RenderNodeAction.Skip
End If
Else
Return RenderNodeAction.Proceed
End If
OnElementBegin2D_Overridable(node)
End Function
Public Overridable Sub OnElementBegin2D_Overridable(node As ElementNode)
End Sub
Public Function OnElementBegin(elementId As ElementId) As RenderNodeAction Implements IExportContext.OnElementBegin
'Never called for 2D export
Return DefaultAction
End Function
Public Function OnInstanceBegin(node As InstanceNode) As RenderNodeAction Implements IExportContext.OnInstanceBegin
Return DefaultAction
End Function
Public Function OnFaceBegin(node As FaceNode) As RenderNodeAction Implements IExportContext.OnFaceBegin
Return DefaultAction
End Function
Public Overridable Function OnFaceEdge2D(node As FaceEdgeNode) As RenderNodeAction Implements IExportContext2D.OnFaceEdge2D
Return DefaultAction
End Function
Public Function OnLinkBegin(node As LinkNode) As RenderNodeAction Implements IExportContext.OnLinkBegin
Return DefaultAction
End Function
#End Region
#Region "OnFunctions_Returns"
Public Overridable Function OnFaceSilhouette2D(node As FaceSilhouetteNode) As RenderNodeAction Implements IExportContext2D.OnFaceSilhouette2D
Return DefaultAction
End Function
Public Overridable Function OnCurve(node As CurveNode) As RenderNodeAction Implements IExportContextBase.OnCurve
Return DefaultAction
End Function
Public Overridable Function OnPolyline(node As PolylineNode) As RenderNodeAction Implements IExportContextBase.OnPolyline
Return DefaultAction
End Function
#End Region
#Region "OnEnds_NoReturns"
Public Sub OnElementEnd2D(node As ElementNode) Implements IExportContext2D.OnElementEnd2D
IntCurrentEID = Nothing
OnElementEnd2D_Overridable(node)
End Sub
Public Overridable Sub OnElementEnd2D_Overridable(node As ElementNode)
End Sub
Public Overridable Sub OnViewEnd(elementId As ElementId) Implements IExportContext.OnViewEnd
End Sub
Public Sub OnElementEnd(elementId As ElementId) Implements IExportContext.OnElementEnd
End Sub
Public Overridable Sub OnInstanceEnd(node As InstanceNode) Implements IExportContext.OnInstanceEnd
End Sub
Public Overridable Sub OnLinkEnd(node As LinkNode) Implements IExportContext.OnLinkEnd
End Sub
Public Overridable Sub OnFaceEnd(node As FaceNode) Implements IExportContext.OnFaceEnd
End Sub
#End Region
#Region "OnSubs_NoReturns"
Public Overridable Sub OnLineSegment(segment As LineSegment) Implements IExportContextBase.OnLineSegment
End Sub
Public Overridable Sub OnPolylineSegments(segments As PolylineSegments) Implements IExportContextBase.OnPolylineSegments
End Sub
Public Sub OnText(node As TextNode) Implements IExportContextBase.OnText
'For tags etc. some calls to this will be during on instance
'e.g. fixed text within family
'Some call will be outside OnInstance but before OnElementEnd2D of associated element
'e.g. tag values (variable text).
If IntCurrentEID = ElementId.InvalidElementId Then Exit Sub Else
OnText_Overridable(node)
End Sub
Public Overridable Sub OnText_Overridable(node As TextNode)
End Sub
Public Overridable Sub OnRPC(node As RPCNode) Implements IExportContext.OnRPC
End Sub
Public Overridable Sub OnLight(node As LightNode) Implements IExportContext.OnLight
End Sub
Public Overridable Sub OnMaterial(node As MaterialNode) Implements IExportContext.OnMaterial
End Sub
Public Overridable Sub OnPolymesh(node As PolymeshTopology) Implements IExportContext.OnPolymesh
End Sub
#End Region
End Class
A lot of the members are not called for the 2D scenario.
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