Edit Hatch Boundaries (.NET)

You can append, insert, or remove loops from the boundaries of a Hatch object. Associative hatches are updated to match any changes made to their boundaries. Non-associative hatches are not updated.

To edit a hatch boundary, use one of the following methods:

AppendLoop

Appends a loop to the hatch. You define the type of loop being appended with first parameter of the AppendLoop method and the constants defined by the HatchLoopTypes enum.

GetLoopAt

Gets the loop at a given index of a hatch.

InsertLoopAt

Inserts a loop at a given index of a hatch.

RemoveLoopAt

Deletes a loop at a given index of a hatch.

To query a hatch boundary, use one of the following methods:

LoopTypeAt

Gets the type of loop at a given index of a hatch.

NumberOfLoops

Gets the number of loops of a hatch.

Append an inner loop to a hatch

This example creates an associative hatch. It then creates a circle and appends the circle as an inner loop to the hatch.

C# Example

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
 
[CommandMethod("EditHatchAppendLoop")]
public static void EditHatchAppendLoop()
{
    // Get the current document and database
    Document acDoc = Application.DocumentManager.MdiActiveDocument;
    Database acCurDb = acDoc.Database;

    // Start a transaction
    using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
    {
        // Open the Block table for read
        BlockTable acBlkTbl;
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                     OpenMode.ForRead) as BlockTable;

        // Open the Block table record Model space for write
        BlockTableRecord acBlkTblRec;
        acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                        OpenMode.ForWrite) as BlockTableRecord;

        // Create an arc object for the closed boundary to hatch
        using (Arc acArc = new Arc(new Point3d(5, 3, 0), 3, 0, 3.141592))
        {

            acBlkTblRec.AppendEntity(acArc);
            acTrans.AddNewlyCreatedDBObject(acArc, true);

            // Create an line object for the closed boundary to hatch
            using (Line acLine = new Line(acArc.StartPoint, acArc.EndPoint))
            {
                acBlkTblRec.AppendEntity(acLine);
                acTrans.AddNewlyCreatedDBObject(acLine, true);

                // Adds the arc and line to an object id collection
                ObjectIdCollection acObjIdColl = new ObjectIdCollection();
                acObjIdColl.Add(acArc.ObjectId);
                acObjIdColl.Add(acLine.ObjectId);

                // Create the hatch object and append it to the block table record
                using (Hatch acHatch = new Hatch())
                {
                    acBlkTblRec.AppendEntity(acHatch);
                    acTrans.AddNewlyCreatedDBObject(acHatch, true);

                    // Set the properties of the hatch object
                    // Associative must be set after the hatch object is appended to the 
                    // block table record and before AppendLoop
                    acHatch.SetHatchPattern(HatchPatternType.PreDefined, "ANSI31");
                    acHatch.Associative = true;
                    acHatch.AppendLoop(HatchLoopTypes.Outermost, acObjIdColl);

                    // Create a circle object for the inner boundary of the hatch
                    using (Circle acCirc = new Circle())
                    {
                        acCirc.Center = new Point3d(5, 4.5, 0);
                        acCirc.Radius = 1;

                        acBlkTblRec.AppendEntity(acCirc);
                        acTrans.AddNewlyCreatedDBObject(acCirc, true);

                        // Adds the circle to an object id collection
                        acObjIdColl.Clear();
                        acObjIdColl.Add(acCirc.ObjectId);

                        // Append the circle as the inner loop of the hatch and evaluate it
                        acHatch.AppendLoop(HatchLoopTypes.Default, acObjIdColl);
                        acHatch.EvaluateHatch(true);
                    }
                }
            }
        }

        // Save the new object to the database
        acTrans.Commit();
    }
}