feat: Allow empty groups

joezearing · Feb 27, 2021 · b870b25 · b870b25
1 parent 9781661
commit b870b25
Show file tree

Hide file tree

Showing 3 changed files with 14 additions and 8 deletions.
diff --git a/src/Blazor.Diagrams.Core/Diagram.cs b/src/Blazor.Diagrams.Core/Diagram.cs
@@ -138,15 +138,15 @@ public GroupModel Group(params NodeModel[] children)
         /// <param name="group">A group instance.</param>
         public void AddGroup(GroupModel group)
         {
-            if (group.Children.Length < 2)
-                throw new ArgumentException("Number of nodes must be >= 2");
-
-            var layers = group.Children.Select(n => n.Layer).Distinct();
-            if (layers.Count() > 1)
-                throw new InvalidOperationException("Cannot group nodes with different layers");
+            if (group.Children.Length > 0)
+            {
+                var layers = group.Children.Select(n => n.Layer).Distinct();
+                if (layers.Count() > 1)
+                    throw new InvalidOperationException("Cannot group nodes with different layers");
 
-            if (layers.First() == RenderLayer.SVG)
-                throw new InvalidOperationException("SVG groups aren't implemented yet");
+                if (layers.First() == RenderLayer.SVG)
+                    throw new InvalidOperationException("SVG groups aren't implemented yet");
+            }
 
             foreach (var child in group.Children)
             {

diff --git a/src/Blazor.Diagrams.Core/Extensions/DiagramExtensions.cs b/src/Blazor.Diagrams.Core/Extensions/DiagramExtensions.cs
@@ -1,13 +1,17 @@
 using Blazor.Diagrams.Core.Models;
 using Blazor.Diagrams.Core.Models.Core;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace Blazor.Diagrams.Core.Extensions
 {
     public static class DiagramExtensions
     {
         public static Rectangle GetBounds(this IEnumerable<NodeModel> nodes)
         {
+            if (!nodes.Any())
+                return Rectangle.Zero;
+
             var minX = double.MaxValue;
             var maxX = double.MinValue;
             var minY = double.MaxValue;

diff --git a/src/Blazor.Diagrams.Core/Models/Core/Rectangle.cs b/src/Blazor.Diagrams.Core/Models/Core/Rectangle.cs
@@ -4,6 +4,8 @@ namespace Blazor.Diagrams.Core.Models.Core
 {
     public class Rectangle
     {
+        public static Rectangle Zero { get; } = new Rectangle(0, 0, 0, 0);
+
         public double Width { get; set; }
         public double Height { get; set; }
         public double Top { get; set; }