Pre work on SizeSystem

MonoDreams.Examples/Screens/MainMenuScreen.cs

@@ -41,6 +41,7 @@ public MainMenuScreen(GraphicsDevice graphicsDevice, ContentManager content, Cam
             new CollisionDetectionSystem(World, parallelRunner),
             new ButtonSystem(World),
             new LayoutSystem(World, renderer),
+            new SizeSystem(World, parallelRunner),
             new PositionSystem(World, parallelRunner),
             new BeginDrawSystem(spriteBatch, renderer, camera),
             new DrawSystem(World, spriteBatch),
@@ -65,7 +66,6 @@ public void Load(ScreenController screenController, ContentManager content)
             AlignItems = YogaAlign.Center,
             JustifyContent = YogaJustify.Center,
             Padding = 20,
-            FlexDirection = YogaFlexDirection.Column,
         });
 
         World.CreateButton(rootLayout, "Start", () => { }, Vector2.Zero, font, Color.Pink, Color.Red, DrawLayer.Buttons);

MonoDreams/Extensions/UIExtensions.cs

@@ -1,6 +1,7 @@
 #nullable enable
 using System;
 using DefaultEcs;
+using Facebook.Yoga;
 using Microsoft.Xna.Framework;
 using MonoDreams.Component;
 using MonoGame.Extended;
@@ -49,13 +50,14 @@ public static Entity CreateButton(
         defaultColor ??= Color.White;
         selectedColor ??= Color.Black;
 
-        var buttonEntity = world.CreateLayoutEntity(parent: layoutParent);
-
-        ref var layoutNode = ref buttonEntity.Get<LayoutNode>();
-        layoutNode.Node.Width = size.X;
-        layoutNode.Node.Height = size.Y;
-        layoutNode.Node.MarginTop = 20;
-        layoutNode.Node.MarginBottom = 20;
+        var buttonEntity = world.CreateLayoutEntity(
+            parent: layoutParent,
+            yogaNode: new YogaNode
+            {
+                Width = size.X,
+                Height = size.Y,
+                Margin = 20,
+            });
 
         buttonEntity.Set(new Position(position));
         buttonEntity.Set(new Collidable(new Rectangle(size / new Point(-2, -2), size)));

MonoDreams/Message/SizeChangeMessage.cs

@@ -0,0 +1,5 @@
+using DefaultEcs;
+
+namespace MonoDreams.Message;
+
+public readonly record struct SizeChangeMessage(Entity entity);

MonoDreams/Size.cs

@@ -0,0 +1,12 @@
+using Microsoft.Xna.Framework;
+
+namespace MonoDreams;
+
+public struct Size
+{
+    public Vector2 CurrentSize;
+    public Vector2 NextSize;
+    public Vector2 LastSize;
+
+    public bool HasUpdates => CurrentSize != NextSize || LastSize != CurrentSize;
+}

MonoDreams/System/SizeSystem.cs

@@ -0,0 +1,28 @@
+using DefaultEcs;
+using DefaultEcs.System;
+using DefaultEcs.Threading;
+using MonoDreams.Message;
+using MonoDreams.State;
+
+namespace MonoDreams.System;
+
+public sealed class SizeSystem : AEntitySetSystem<GameState>
+{
+    private readonly World _world;
+
+    public SizeSystem(World world, IParallelRunner runner)
+        : base(world.GetEntities().With((in Size p) => p.HasUpdates).AsSet(), runner)
+    {
+        _world = world;
+    }
+
+    protected override void Update(GameState state, in Entity entity)
+    {
+        ref var size = ref entity.Get<Size>();
+        size.LastSize.X = size.CurrentSize.X;
+        size.LastSize.Y = size.CurrentSize.Y;
+        size.CurrentSize.X = size.NextSize.X;
+        size.CurrentSize.Y = size.NextSize.Y;
+        _world.Publish(new SizeChangeMessage(entity));
+    }
+}