[2023/04/27]

* Removed the taget frameworks netstandard2.1, netcoreapp3.1, and net5.0. Manually edit the netDxf.proj if you need them.
* Reworked how the references to a TableObject are tracked. Now they are internally stored in a dictionary instead of a list. While this will make adding entities to the document a little slower removing them will be much faster. See the sample TableObjectReferences().
* Add the method GetReferences to classes that inherit from TableObject. It returns the same list as the GetReferences method of its respective collection. See the sample TableObjectReferences().
* Added the method HasReferences to TableObjects and TableObject collections. It indicates if the actual table object has been referenced by other DxfObjects. TableObjects in use cannot be removed.
* Added a check to avoid initializing a bezier curve with the wrong number of control points.
* (fixed) Removing dimension entities with no associated block. This is the case of dimensions whick block has left null to force the program that loads the resulting DXF to generate its own dimension block.
* (fixed) Error when loading a closed periodic spline from a DXF without weights.

Author: haplokuon

TestDxfDocument/Program.cs

@@ -1,5 +1,14 @@
 ## Change history
 
+### [2023/04/27]
+* Removed the taget frameworks netstandard2.1, netcoreapp3.1, and net5.0. Manually edit the netDxf.proj if you need them.
+* Reworked how the references to a TableObject are tracked. Now they are internally stored in a dictionary instead of a list. While this will make adding entities to the document a little slower removing them will be much faster. See the sample TableObjectReferences().
+* Add the method GetReferences to classes that inherit from TableObject. It returns the same list as the GetReferences method of its respective collection. See the sample TableObjectReferences().
+* Added the method HasReferences to TableObjects and TableObject collections. It indicates if the actual table object has been referenced by other DxfObjects. TableObjects in use cannot be removed.
+* Added a check to avoid initializing a bezier curve with the wrong number of control points.
+* (fixed) Removing dimension entities with no associated block. This is the case of dimensions whick block has left null to force the program that loads the resulting DXF to generate its own dimension block.
+* (fixed) Error when loading a closed periodic spline from a DXF without weights.
+
 ### [2023/03/05]
 * Changed the default target framework 'net45' for 'net48'. The library is compatible will all 4.x net framework versions.
 * Renamed the constant 'NET45' with 'NET4X' in netDxf.csproj. This constant must be applicable when compiling against any net framework 4.x versions.

doc/Changelog.txt

@@ -643,25 +643,6 @@ public static byte RgbToAci(byte r, byte g, byte b)
                 }
             }
 
-            //byte index = 0;
-            //foreach (byte[]  in IndexRgb.Keys)
-            //{
-            //    byte[] color = IndexRgb[key];
-            //    int red = r - color[0];
-            //    int green = g - color[1];
-            //    int blue = b - color[2];
-            //    int dist = red * red + green * green + blue * blue;
-            //    if (dist == 0) // the RGB components correspond to one of the indexed colors
-            //    {
-            //        return key;
-            //    }
-            //    if (dist < prevDist)
-            //    {
-            //        prevDist = dist;
-            //        index = key;
-            //    }
-            //}
-
             return index;
         }
 

netDxf/AciColor.cs

@@ -1,7 +1,7 @@
 #region netDxf library licensed under the MIT License
 // 
 //                       netDxf library
-// Copyright (c) 2019-2021 Daniel Carvajal (haplokuon@gmail.com)
+// Copyright (c) 2019-2023 Daniel Carvajal (haplokuon@gmail.com)
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -47,18 +47,28 @@ public abstract class BezierCurve
         /// Initializes a new instance of the <c>BezierCurve</c> class.
         /// </summary>
         /// <param name="controlPoints">A list of control points.</param>
+        /// <param name="degree">Bezier curve degree.</param>
         /// <remarks>
-        /// The curve degree will be equal to the number of control points minus one.
+        /// The curve degree must be equal to the number of control points minus one.
         /// </remarks>
-        protected BezierCurve(IEnumerable<Vector3> controlPoints)
+        protected BezierCurve(IEnumerable<Vector3> controlPoints, int degree)
         {
             if (controlPoints == null)
             {
                 throw new ArgumentNullException(nameof(controlPoints));
             }
+            if (degree < 1)
+            {
+                throw new ArgumentOutOfRangeException(nameof(degree), degree, "The bezier curve degree must be at least one.");
+            }
 
             this.controlPoints = controlPoints.ToArray();
-            this.degree = this.controlPoints.Length - 1;
+            this.degree = degree;
+            
+            if (this.degree != this.controlPoints.Length - 1)
+            {
+                throw new ArgumentException("The bezier curve degree must be equal to the number of control points minus one.");
+            }
         }
 
         #endregion

netDxf/BezierCurve.cs

@@ -1,7 +1,7 @@
 #region netDxf library licensed under the MIT License
 // 
 //                       netDxf library
-// Copyright (c) 2019-2021 Daniel Carvajal (haplokuon@gmail.com)
+// Copyright (c) 2019-2023 Daniel Carvajal (haplokuon@gmail.com)
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -49,7 +49,7 @@ public class BezierCurveCubic :
         /// and the last the end point.
         /// </remarks>
         public BezierCurveCubic(IEnumerable<Vector3> controlPoints)
-            : base(controlPoints)
+            : base(controlPoints, 3)
         {
         }
 
@@ -61,7 +61,7 @@ public BezierCurveCubic(IEnumerable<Vector3> controlPoints)
         /// <param name="secondControlPoint">Second control point.</param>
         /// <param name="endPoint">End anchor point.</param>
         public BezierCurveCubic(Vector3 startPoint, Vector3 firstControlPoint, Vector3 secondControlPoint, Vector3 endPoint)
-            : base(new[]{startPoint, firstControlPoint, secondControlPoint, endPoint})
+            : base(new[]{startPoint, firstControlPoint, secondControlPoint, endPoint}, 3)
         {
         }
 
@@ -207,10 +207,9 @@ public List<Vector3> PolygonalVertexes(int precision)
         /// <param name="fitPoints">List of points.</param>
         /// <returns>A list of cubic bezier curves.</returns>
         /// <returns>
-        /// Original https://www.codeproject.com/Articles/31859/Draw-a-Smooth-Curve-through-a-Set-of-2D-Points-wit by Oleg V. Polikarpotchkin and Peter Lee.
+        /// Original code: https://www.codeproject.com/Articles/31859/Draw-a-Smooth-Curve-through-a-Set-of-2D-Points-wit by Oleg V. Polikarpotchkin and Peter Lee.<br />
         /// Modified to allow the use of 3D points, and other minor changes to accomodate the existing classes of this library.<br />
-        /// The total number of curves returned will be equal to the number of fit points minus 1,
-        /// therefore this method is not suitable to use over large number of fit points,
+        /// The total number of curves returned will be equal to the number of fit points minus 1, therefore this method is not suitable to use over large number of fit points,
         /// where other, more computational heavy methods, like the least-squares bezier curve fitting would return a less amount of curves.
         /// In such cases, it is advisable to perform some method to reduce the number of points and to avoid duplicates or very close points.
         /// </returns>
@@ -269,7 +268,7 @@ public static List<BezierCurveCubic> CreateFromFitPoints(IEnumerable<Vector3> fi
             // Get first control points Y-values
             double[] y = GetFirstControlPoints(rhs);
 
-            // Set right hand side Y values
+            // Set right hand side Z values
             for (int i = 1; i < n - 1; i++)
             {
                 rhs[i] = 4.0 * points[i].Z + 2.0 * points[i + 1].Z;

netDxf/BezierCurveCubic.cs

@@ -1,7 +1,7 @@
 #region netDxf library licensed under the MIT License
 // 
 //                       netDxf library
-// Copyright (c) 2019-2021 Daniel Carvajal (haplokuon@gmail.com)
+// Copyright (c) 2019-2023 Daniel Carvajal (haplokuon@gmail.com)
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -47,7 +47,7 @@ public class BezierCurveQuadratic :
         /// and the last the end point.
         /// </remarks>
         public BezierCurveQuadratic(IEnumerable<Vector3> controlPoints)
-            : base(controlPoints)
+            : base(controlPoints, 2)
         {
         }
 
@@ -58,7 +58,7 @@ public BezierCurveQuadratic(IEnumerable<Vector3> controlPoints)
         /// <param name="controlPoint">Second control point.</param>
         /// <param name="endPoint">End anchor point.</param>
         public BezierCurveQuadratic(Vector3 startPoint, Vector3 controlPoint, Vector3 endPoint)
-            : base (new []{startPoint, controlPoint, endPoint})
+            : base (new []{startPoint, controlPoint, endPoint}, 2)
         {
         }
 

netDxf/BezierCurveQuadratic.cs

@@ -1,7 +1,7 @@
 #region netDxf library licensed under the MIT License
 // 
 //                       netDxf library
-// Copyright (c) 2019-2021 Daniel Carvajal (haplokuon@gmail.com)
+// Copyright (c) 2019-2023 Daniel Carvajal (haplokuon@gmail.com)
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -598,6 +598,41 @@ public bool Save(string file, DxfVersion version, bool isBinary)
 
         #region overrides
 
+        /// <summary>
+        /// Checks if this instance has been referenced by other DxfObjects. 
+        /// </summary>
+        /// <returns>
+        /// Returns true if this instance has been referenced by other DxfObjects, false otherwise.
+        /// It will always return false if this instance does not belong to a document.
+        /// </returns>
+        /// <remarks>
+        /// This method returns the same value as the HasReferences method that can be found in the TableObjects class.
+        /// </remarks>
+        public override bool HasReferences()
+        {
+            return this.Owner.Owner != null && this.Owner.Owner.HasReferences(this.Name);
+        }
+
+        /// <summary>
+        /// Gets the list of DxfObjects referenced by this instance.
+        /// </summary>
+        /// <returns>
+        /// A list of DxfObjectReference that contains the DxfObject referenced by this instance and the number of times it does.
+        /// It will return null if this instance does not belong to a document.
+        /// </returns>
+        /// <remarks>
+        /// This method returns the same list as the GetReferences method that can be found in the TableObjects class.
+        /// </remarks>
+        public override List<DxfObjectReference> GetReferences()
+        {
+            if (this.Owner.Owner == null)
+            {
+                return null;
+            }
+
+            return this.Owner.Owner.GetReferences(this.Name);
+        }
+
         private static TableObject Clone(Block block, string newName, bool checkName)
         {
             if (block.Record.Layout != null && !IsValidName(newName))

netDxf/Blocks/Block.cs

@@ -1,7 +1,7 @@
 #region netDxf library licensed under the MIT License
 // 
 //                       netDxf library
-// Copyright (c) 2019-2021 Daniel Carvajal (haplokuon@gmail.com)
+// Copyright (c) 2019-2023 Daniel Carvajal (haplokuon@gmail.com)
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -25,6 +25,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using netDxf.Tables;
 
 namespace netDxf.Collections
@@ -67,7 +68,7 @@ internal override ApplicationRegistry Add(ApplicationRegistry appReg, bool assig
                 throw new ArgumentNullException(nameof(appReg));
             }
 
-            if (this.list.TryGetValue(appReg.Name, out ApplicationRegistry add))
+            if (this.List.TryGetValue(appReg.Name, out ApplicationRegistry add))
             {
                 return add;
             }
@@ -77,13 +78,14 @@ internal override ApplicationRegistry Add(ApplicationRegistry appReg, bool assig
                 this.Owner.NumHandles = appReg.AssignHandle(this.Owner.NumHandles);
             }
 
-            this.list.Add(appReg.Name, appReg);
-            this.references.Add(appReg.Name, new List<DxfObject>());
+            this.List.Add(appReg.Name, appReg);
+            this.References.Add(appReg.Name, new DxfObjectReferences());
 
             appReg.Owner = this;
 
             appReg.NameChanged += this.Item_NameChanged;
 
+            Debug.Assert(!string.IsNullOrEmpty(appReg.Handle), "The application registry handle cannot be null or empty.");
             this.Owner.AddedObjects.Add(appReg.Handle, appReg);
 
             return appReg;
@@ -123,14 +125,14 @@ public override bool Remove(ApplicationRegistry item)
                 return false;
             }
 
-            if (this.references[item.Name].Count != 0)
+            if (this.HasReferences(item))
             {
                 return false;
             }
 
             this.Owner.AddedObjects.Remove(item.Handle);
-            this.references.Remove(item.Name);
-            this.list.Remove(item.Name);
+            this.References.Remove(item.Name);
+            this.List.Remove(item.Name);
 
             item.Handle = null;
             item.Owner = null;
@@ -151,12 +153,13 @@ private void Item_NameChanged(TableObject sender, TableObjectChangedEventArgs<st
                 throw new ArgumentException("There is already another application registry with the same name.");
             }
 
-            this.list.Remove(sender.Name);
-            this.list.Add(e.NewValue, (ApplicationRegistry) sender);
+            this.List.Remove(sender.Name);
+            this.List.Add(e.NewValue, (ApplicationRegistry) sender);
 
-            List<DxfObject> refs = this.references[sender.Name];
-            this.references.Remove(sender.Name);
-            this.references.Add(e.NewValue, refs);
+            List<DxfObjectReference> refs = this.References[sender.Name].ToList();
+            this.References.Remove(sender.Name);
+            this.References.Add(e.NewValue, new DxfObjectReferences());
+            this.References[e.NewValue].Add(refs);
         }
 
         #endregion

netDxf/Collections/ApplicationRegistries.cs

@@ -1,7 +1,7 @@
 #region netDxf library licensed under the MIT License
 // 
 //                       netDxf library
-// Copyright (c) 2019-2021 Daniel Carvajal (haplokuon@gmail.com)
+// Copyright (c) 2019-2023 Daniel Carvajal (haplokuon@gmail.com)
 // 
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
@@ -25,6 +25,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using netDxf.Blocks;
 using netDxf.Entities;
 using netDxf.Tables;
@@ -69,7 +70,7 @@ internal override Block Add(Block block, bool assignHandle)
                 throw new ArgumentNullException(nameof(block));
             }
 
-            if (this.list.TryGetValue(block.Name, out Block add))
+            if (this.List.TryGetValue(block.Name, out Block add))
             {
                 return add;
             }
@@ -79,16 +80,16 @@ internal override Block Add(Block block, bool assignHandle)
                 this.Owner.NumHandles = block.AssignHandle(this.Owner.NumHandles);
             }
 
-            this.list.Add(block.Name, block);
-            this.references.Add(block.Name, new List<DxfObject>());
+            this.List.Add(block.Name, block);
+            this.References.Add(block.Name, new DxfObjectReferences());
 
             block.Layer = this.Owner.Layers.Add(block.Layer);
             this.Owner.Layers.References[block.Layer.Name].Add(block);
 
             //for new block definitions configure its entities
             foreach (EntityObject entity in block.Entities)
             {
-                this.Owner.AddEntityToDocument(entity, block, assignHandle);
+                this.Owner.AddEntityToDocument(entity, assignHandle);
             }
 
             //for new block definitions configure its attributes
@@ -106,6 +107,7 @@ internal override Block Add(Block block, bool assignHandle)
             block.AttributeDefinitionAdded += this.Block_AttributeDefinitionAdded; 
             block.AttributeDefinitionRemoved += this.Block_AttributeDefinitionRemoved;
 
+            Debug.Assert(!string.IsNullOrEmpty(block.Handle), "The block handle cannot be null or empty.");
             this.Owner.AddedObjects.Add(block.Handle, block);
             this.Owner.AddedObjects.Add(block.Owner.Handle, block.Owner);
 
@@ -146,7 +148,7 @@ public override bool Remove(Block item)
                 return false;
             }
 
-            if (this.references[item.Name].Count != 0)
+            if (this.HasReferences(item))
             {
                 return false;
             }
@@ -167,8 +169,8 @@ public override bool Remove(Block item)
             }
 
             this.Owner.AddedObjects.Remove(item.Handle);
-            this.references.Remove(item.Name);
-            this.list.Remove(item.Name);
+            this.References.Remove(item.Name);
+            this.List.Remove(item.Name);
 
             item.Record.Handle = null;
             item.Record.Owner = null;
@@ -197,12 +199,13 @@ private void Item_NameChanged(TableObject sender, TableObjectChangedEventArgs<st
                 throw new ArgumentException("There is already another block with the same name.");
             }
 
-            this.list.Remove(sender.Name);
-            this.list.Add(e.NewValue, (Block) sender);
+            this.List.Remove(sender.Name);
+            this.List.Add(e.NewValue, (Block) sender);
 
-            List<DxfObject> refs = this.references[sender.Name];
-            this.references.Remove(sender.Name);
-            this.references.Add(e.NewValue, refs);
+            List<DxfObjectReference> refs = this.GetReferences(sender.Name);
+            this.References.Remove(sender.Name);
+            this.References.Add(e.NewValue, new DxfObjectReferences());
+            this.References[e.NewValue].Add(refs);
         }
 
         private void Block_LayerChanged(Block sender, TableObjectChangedEventArgs<Layer> e)
@@ -215,7 +218,7 @@ private void Block_LayerChanged(Block sender, TableObjectChangedEventArgs<Layer>
 
         private void Block_EntityAdded(TableObject sender, BlockEntityChangeEventArgs e)
         {
-            this.Owner.AddEntityToDocument(e.Item, (Block) sender, string.IsNullOrEmpty(e.Item.Handle));
+            this.Owner.AddEntityToDocument(e.Item, string.IsNullOrEmpty(e.Item.Handle));
         }
 
         private void Block_EntityRemoved(TableObject sender, BlockEntityChangeEventArgs e)