You can define a region of an external reference for display and plotting by clipping the external reference. The clipping boundary must be a 2D polygon or rectangle with vertices constrained to lie within the boundaries of the external reference. Multiple instances of the same external reference can have different boundaries.
The SpatialFilter and SpatialFilterDefinition objects are used to define the properties of the clipping boundary for an external reference. Use the Enabled property of the SpatialFilterDefinition object show or hide the clipping boundary.
This example attaches an external reference and then clips the external reference so only part of it is displayed. This example uses the Exterior Elevations.dwg file found in the Sample directory. If you do not have this image, or if it is located in a different directory, insert a valid path and file name.
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
<CommandMethod("ClippingExternalReference")> _
Public Sub ClippingExternalReference()
' Get the current database and start a transaction
Dim acCurDb As Autodesk.AutoCAD.DatabaseServices.Database
acCurDb = Application.DocumentManager.MdiActiveDocument.Database
Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()
' Create a reference to a DWG file
Dim PathName As String = "C:\AutoCAD\Sample\Sheet Sets\Architectural\Res\Exterior Elevations.dwg"
Dim acXrefId As ObjectId = acCurDb.AttachXref(PathName, "Exterior Elevations")
' If a valid reference is created then continue
If Not acXrefId.IsNull Then
' Attach the DWG reference to the current space
Dim insPt As New Point3d(1, 1, 0)
Using acBlkRef As New BlockReference(insPt, acXrefId)
Dim acBlkTblRec As BlockTableRecord
acBlkTblRec = acTrans.GetObject(acCurDb.CurrentSpaceId, OpenMode.ForWrite)
acBlkTblRec.AppendEntity(acBlkRef)
acTrans.AddNewlyCreatedDBObject(acBlkRef, True)
MsgBox("The external reference is attached.")
Dim mat As Matrix3d = acBlkRef.BlockTransform
mat.Inverse()
Dim ptCol As New Point2dCollection
' Define the first corner of the clipping boundary
Dim pt3d As New Point3d(-330, 400, 0)
pt3d.TransformBy(mat)
ptCol.Add(New Point2d(pt3d.X, pt3d.Y))
' Define the second corner of the clipping boundary
pt3d = New Point3d(1320, 1120, 0)
pt3d.TransformBy(mat)
ptCol.Add(New Point2d(pt3d.X, pt3d.Y))
' Define the normal and elevation for the clipping boundary
Dim normal As Vector3d
Dim elev As Double = 0
If acCurDb.TileMode = True Then
normal = acCurDb.Ucsxdir.CrossProduct(acCurDb.Ucsydir)
elev = acCurDb.Elevation
Else
normal = acCurDb.Pucsxdir.CrossProduct(acCurDb.Pucsydir)
elev = acCurDb.Pelevation
End If
' Set the clipping boundary and enable it
Using filter As New Filters.SpatialFilter
Dim filterDef As New Filters.SpatialFilterDefinition(ptCol, normal, elev, 0, 0, True)
filter.Definition = filterDef
' Define the name of the extension dictionary and entry name
Dim dictName As String = "ACAD_FILTER"
Dim spName As String = "SPATIAL"
' Check to see if the Extension Dictionary exists, if not create it
If acBlkRef.ExtensionDictionary.IsNull Then
acBlkRef.UpgradeOpen()
acBlkRef.CreateExtensionDictionary()
acBlkRef.DowngradeOpen()
End If
' Open the Extension Dictionary for write
Dim extDict As DBDictionary = acTrans.GetObject(acBlkRef.ExtensionDictionary, OpenMode.ForWrite)
' Check to see if the dictionary for clipped boundaries exists,
' and add the spatial filter to the dictionary
If extDict.Contains(dictName) Then
Dim filterDict As DBDictionary = acTrans.GetObject(extDict.GetAt(dictName), OpenMode.ForWrite)
If (filterDict.Contains(spName)) Then filterDict.Remove(spName)
filterDict.SetAt(spName, filter)
Else
Using filterDict As New DBDictionary
extDict.SetAt(dictName, filterDict)
acTrans.AddNewlyCreatedDBObject(filterDict, True)
filterDict.SetAt(spName, filter)
End Using
End If
' Append the spatial filter to the drawing
acTrans.AddNewlyCreatedDBObject(filter, True)
End Using
End Using
MsgBox("The external reference is clipped.")
End If
' Save the new objects to the database
acTrans.Commit()
' Dispose of the transaction
End Using
End Sub
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
[CommandMethod("ClippingExternalReference")]
public void ClippingExternalReference()
{
// Get the current database and start a transaction
Database acCurDb;
acCurDb = Application.DocumentManager.MdiActiveDocument.Database;
using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{
// Create a reference to a DWG file
string PathName = "C:\\AutoCAD\\Sample\\Sheet Sets\\Architectural\\Res\\Exterior Elevations.dwg";
ObjectId acXrefId = acCurDb.AttachXref(PathName, "Exterior Elevations");
// If a valid reference is created then continue
if (!acXrefId.IsNull)
{
// Attach the DWG reference to the current space
Point3d insPt = new Point3d(1, 1, 0);
using (BlockReference acBlkRef = new BlockReference(insPt, acXrefId))
{
BlockTableRecord acBlkTblRec;
acBlkTblRec = acTrans.GetObject(acCurDb.CurrentSpaceId, OpenMode.ForWrite) as BlockTableRecord;
acBlkTblRec.AppendEntity(acBlkRef);
acTrans.AddNewlyCreatedDBObject(acBlkRef, true);
Application.ShowAlertDialog("The external reference is attached.");
Matrix3d mat = acBlkRef.BlockTransform;
mat.Inverse();
Point2dCollection ptCol = new Point2dCollection();
// Define the first corner of the clipping boundary
Point3d pt3d = new Point3d(-330, 400, 0);
pt3d.TransformBy(mat);
ptCol.Add(new Point2d(pt3d.X, pt3d.Y));
// Define the second corner of the clipping boundary
pt3d = new Point3d(1320, 1120, 0);
pt3d.TransformBy(mat);
ptCol.Add(new Point2d(pt3d.X, pt3d.Y));
// Define the normal and elevation for the clipping boundary
Vector3d normal;
double elev = 0;
if (acCurDb.TileMode == true)
{
normal = acCurDb.Ucsxdir.CrossProduct(acCurDb.Ucsydir);
elev = acCurDb.Elevation;
}
else
{
normal = acCurDb.Pucsxdir.CrossProduct(acCurDb.Pucsydir);
elev = acCurDb.Pelevation;
}
// Set the clipping boundary and enable it
using (Autodesk.AutoCAD.DatabaseServices.Filters.SpatialFilter filter =
new Autodesk.AutoCAD.DatabaseServices.Filters.SpatialFilter())
{
Autodesk.AutoCAD.DatabaseServices.Filters.SpatialFilterDefinition filterDef =
new Autodesk.AutoCAD.DatabaseServices.Filters.SpatialFilterDefinition(ptCol, normal, elev, 0, 0, true);
filter.Definition = filterDef;
// Define the name of the extension dictionary and entry name
string dictName = "ACAD_FILTER";
string spName = "SPATIAL";
// Check to see if the Extension Dictionary exists, if not create it
if (acBlkRef.ExtensionDictionary.IsNull)
{
acBlkRef.UpgradeOpen();
acBlkRef.CreateExtensionDictionary();
acBlkRef.DowngradeOpen();
}
// Open the Extension Dictionary for write
DBDictionary extDict = acTrans.GetObject(acBlkRef.ExtensionDictionary, OpenMode.ForWrite) as DBDictionary;
// Check to see if the dictionary for clipped boundaries exists,
// and add the spatial filter to the dictionary
if (extDict.Contains(dictName))
{
DBDictionary filterDict = acTrans.GetObject(extDict.GetAt(dictName), OpenMode.ForWrite) as DBDictionary;
if (filterDict.Contains(spName))
{
filterDict.Remove(spName);
}
filterDict.SetAt(spName, filter);
}
else
{
using (DBDictionary filterDict = new DBDictionary())
{
extDict.SetAt(dictName, filterDict);
acTrans.AddNewlyCreatedDBObject(filterDict, true);
filterDict.SetAt(spName, filter);
}
}
// Append the spatial filter to the drawing
acTrans.AddNewlyCreatedDBObject(filter, true);
}
}
Application.ShowAlertDialog("The external reference is clipped.");
}
// Save the new objects to the database
acTrans.Commit();
// Dispose of the transaction
}
}