interfaces for IBehavior & IDragNewLinkBehavior

src/Blazor.Diagrams.Core/Behavior.cs

@@ -2,7 +2,7 @@
 
 namespace Blazor.Diagrams.Core;
 
-public abstract class Behavior : IDisposable
+public abstract class Behavior : IBehavior, IDisposable
 {
     public Behavior(Diagram diagram)
     {

src/Blazor.Diagrams.Core/Behaviors/DragNewLinkBehavior.cs

@@ -7,7 +7,7 @@
 
 namespace Blazor.Diagrams.Core.Behaviors;
 
-public class DragNewLinkBehavior : Behavior
+public class DragNewLinkBehavior : Behavior, IDragNewLinkBehavior
 {
     private PositionAnchor? _targetPositionAnchor;
 

src/Blazor.Diagrams.Core/Behaviors/IDragNewLinkBehavior.cs

@@ -0,0 +1,14 @@
+using Blazor.Diagrams.Core.Models.Base;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Blazor.Diagrams.Core.Behaviors;
+
+public interface IDragNewLinkBehavior : IBehavior
+{
+    BaseLinkModel? OngoingLink { get; }
+    void StartFrom(ILinkable source, double clientX, double clientY);
+}

src/Blazor.Diagrams.Core/Controls/Default/ArrowHeadControl.cs

@@ -46,7 +46,7 @@ public override ValueTask OnPointerDown(Diagram diagram, Model model, PointerEve
         if (model is not BaseLinkModel link)
             throw new DiagramsException("ArrowHeadControl only works for models of type BaseLinkModel");
 
-        var dnlb = diagram.GetBehavior<DragNewLinkBehavior>()!;
+        var dnlb = diagram.GetBehavior<IDragNewLinkBehavior>()!;
         if (Source)
         {
             link.SetSource(link.Target);

src/Blazor.Diagrams.Core/Controls/Default/DragNewLinkControl.cs

@@ -29,7 +29,7 @@ public override ValueTask OnPointerDown(Diagram diagram, Model model, PointerEve
         if (model is not NodeModel node || node.Locked)
             return ValueTask.CompletedTask;
 
-        var behavior = diagram.GetBehavior<DragNewLinkBehavior>();
+        var behavior = diagram.GetBehavior<IDragNewLinkBehavior>();
         if (behavior == null)
             throw new DiagramsException($"DragNewLinkBehavior was not found");
 

src/Blazor.Diagrams.Core/Diagram.cs

@@ -19,7 +19,7 @@ namespace Blazor.Diagrams.Core;
 
 public abstract class Diagram
 {
-    private readonly Dictionary<Type, Behavior> _behaviors;
+    private readonly Dictionary<Type, IBehavior> _behaviors;
     private readonly List<SelectableModel> _orderedSelectables;
 
     public event Action<Model?, PointerEventArgs>? PointerDown;
@@ -40,7 +40,7 @@ public abstract class Diagram
 
     protected Diagram()
     {
-        _behaviors = new Dictionary<Type, Behavior>();
+        _behaviors = new Dictionary<Type, IBehavior>();
         _orderedSelectables = new List<SelectableModel>();
 
         Nodes = new NodeLayer(this);
@@ -58,7 +58,7 @@ protected Diagram()
 
         RegisterBehavior(new SelectionBehavior(this));
         RegisterBehavior(new DragMovablesBehavior(this));
-        RegisterBehavior(new DragNewLinkBehavior(this));
+        RegisterBehavior(new DragNewLinkBehavior(this) as IDragNewLinkBehavior);
         RegisterBehavior(new PanBehavior(this));
         RegisterBehavior(new ZoomBehavior(this));
         RegisterBehavior(new EventsBehavior(this));
@@ -170,22 +170,22 @@ public void UnselectAll()
 
     #region Behaviors
 
-    public void RegisterBehavior(Behavior behavior)
+    public void RegisterBehavior<T>(T behavior) where T : IBehavior
     {
-        var type = behavior.GetType();
+        var type = typeof(T);
         if (_behaviors.ContainsKey(type))
             throw new Exception($"Behavior '{type.Name}' already registered");
 
         _behaviors.Add(type, behavior);
     }
 
-    public T? GetBehavior<T>() where T : Behavior
+    public T? GetBehavior<T>() where T : IBehavior
     {
         var type = typeof(T);
         return (T?)(_behaviors.ContainsKey(type) ? _behaviors[type] : null);
     }
 
-    public void UnregisterBehavior<T>() where T : Behavior
+    public void UnregisterBehavior<T>() where T : IBehavior
     {
         var type = typeof(T);
         if (!_behaviors.ContainsKey(type))
@@ -346,7 +346,7 @@ public int GetMaxOrder()
     public void RefreshOrders(bool refresh = true)
     {
         _orderedSelectables.Sort((a, b) => a.Order.CompareTo(b.Order));
-        
+
         if (refresh)
         {
             Refresh();

src/Blazor.Diagrams.Core/IBehavior.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Blazor.Diagrams.Core;
+
+public interface IBehavior : IDisposable
+{
+}

src/Blazor.Diagrams/Components/LinkWidget.razor

@@ -6,7 +6,7 @@
     if (result == null)
         return;
 
-    var dnlb = BlazorDiagram.GetBehavior<DragNewLinkBehavior>();
+    var dnlb = BlazorDiagram.GetBehavior<IDragNewLinkBehavior>();
     var d = result.FullPath.ToString();
 }