Add debug rectangle size rendering, auto-resize containers to fit all children.

Voile/Source/UI/Containers/Container.cs

@@ -1,29 +1,40 @@
 using System.Numerics;
+using Voile.Rendering;
 
 namespace Voile.UI.Containers;
 
 /// <summary>
 /// A base class for all UI containers, used to position and rendering child <see cref="IElement">s.
 /// </summary>
-public abstract class Container : IElement, IParentableElement, IUpdatableElement
+public abstract class Container : IElement, IParentableElement, IUpdatableElement, IResizeableElement, IRenderableElement
 {
     public IReadOnlyList<IElement> Children => _children;
     public Vector2 Position { get; set; }
+    public Rect MinimumRect { get; set; } = Rect.Zero;
     public Rect Size { get; set; } = Rect.Zero;
+    public bool Visible { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
 
     public Container()
     {
 
     }
 
-    public Container(List<IElement> children)
+    public Container(Rect minimumSize)
     {
+        MinimumRect = minimumSize;
+    }
+
+    public Container(Rect minimumSize, List<IElement> children)
+    {
+        MinimumRect = minimumSize;
         _children = children;
     }
 
     public void Update()
     {
         Arrange();
+        CalculateMinimumSize();
+
         foreach (var child in _children)
         {
             if (child is not IUpdatableElement updatable) continue;
@@ -32,11 +43,59 @@ public abstract class Container : IElement, IParentableElement, IUpdatableElemen
     }
     public abstract void Arrange();
 
+    public void CalculateMinimumSize()
+    {
+        if (Children.Count == 0)
+        {
+            Size = MinimumRect;
+            return;
+        }
+
+        float minX = float.MaxValue;
+        float minY = float.MaxValue;
+        float maxX = float.MinValue;
+        float maxY = float.MinValue;
+
+        foreach (var child in Children)
+        {
+            var pos = child.Position;
+            var size = child.Size;
+
+            minX = MathF.Min(minX, pos.X);
+            minY = MathF.Min(minY, pos.Y);
+            maxX = MathF.Max(maxX, pos.X + size.Width);
+            maxY = MathF.Max(maxY, pos.Y + size.Height);
+        }
+
+        // Optionally apply padding
+        float padding = 0f; // or make this configurable
+
+        Size = new Rect(
+            maxX - minX + padding * 2,
+            maxY - minY + padding * 2
+        );
+    }
+
     public void AddChild(IElement child)
     {
         _children.Add(child);
         Update();
     }
 
+    public void Render(RenderSystem renderer, Style style)
+    {
+        foreach (var child in Children)
+        {
+            if (child is not IRenderableElement renderable) continue;
+            renderable.Render(renderer, style);
+        }
+    }
+
+    public void DrawSize(RenderSystem renderer)
+    {
+        renderer.SetTransform(Position, Vector2.Zero);
+        renderer.DrawRectangleOutline(new Vector2(Size.Width, Size.Height), Color.Red, 2.0f);
+    }
+
     private List<IElement> _children = new();
 }