Hi @C_Haines_ENG. I don't have a good example to test this on, but you can give it a try, and maybe make any tweaks you think it may need, but this code below should be fairly similar to what you are talking about. Right now, it is just set to process one specific view on the active sheet, by its index number, but you can change that part as needed. After the view has been obtained, it then gets all drawing curves for that view into one variable. Then as it loops through them, it checks to see if that geometry represents a 'tangent edge', and if not, skips to next geometry. Then it checks to see if it is a straight line or line segment type geometry. If so, it then measures its length from start point to end point, then attempts to account for view scale, then attempts to convert from 'database units' (centimeters in this case), to document units (which I assume is millimeters in this case). Then, if that value equals 3, it then tries to set visibility of that geometry off for that view.
Dim oDDoc As DrawingDocument = ThisDrawing.Document
Dim oSheet As Sheet = oDDoc.ActiveSheet
Dim oView As DrawingView = oSheet.DrawingViews.Item(2)
Dim oDCurves As DrawingCurvesEnumerator
oDCurves = oView.DrawingCurves
If oDCurves.Count = 0 Then Exit Sub
For Each oDCurve As DrawingCurve In oDCurves
If oDCurve.EdgeType <> DrawingEdgeTypeEnum.kTangentEdge Then Continue For
If oDCurve.CurveType = CurveTypeEnum.kLineCurve Or _
oDCurve.CurveType = CurveTypeEnum.kLineSegmentCurve Then
Dim oLength As Double = oDCurve.StartPoint.DistanceTo(oDCurve.EndPoint)
oLength = oLength / oView.Scale 'divide by view scale
'convert value from database units (centimeters), to document units (millimeters in your case)
oLength = oLength / 10
'MsgBox("Tangent Line Length = " & oLength,,"")
If oLength = 3 Then
oView.SetVisibility(oDCurve, False)
End If
End If
Next
Wesley Crihfield

(Not an Autodesk Employee)