Don't update MarginContainer if it already matches its parent size, update TestGame.

TestGame/TestGame.cs

@@ -20,7 +20,7 @@ public class TestGame : Game
         InitializeSystemsDefault();
 
         _uiSystem = new UISystem(Input, ResourceRef<Style>.Empty());
-        _uiSystem.RenderDebugRects = true;
+        // _uiSystem.RenderDebugRects = true;
 
         _particleSystem = new ParticleSystem();
 
@@ -63,10 +63,32 @@ public class TestGame : Game
         Input.AddInputMapping("reload", new IInputAction[] { new KeyInputAction(KeyboardKey.R) });
         _emitterId = _particleSystem.CreateEmitter(Renderer.WindowSize / 2, _fireEffect);
 
-        // _fillContainer.AddChild(_container);
-        // _marginContainer.AddChild(_container);
+        var addButton = new Button("Add element", _defaultFontSet, () => { _container.AddChild(new Label("Hello, World!", _defaultFontSet)); });
+        addButton.Padding = new Margin(8.0f);
 
-        _uiSystem.AddElement(_container);
+        var removeButton = new Button("Remove element", _defaultFontSet, () =>
+        {
+            if (_container.Children.Count == 0) return;
+            var lastChild = _container.Children.Last();
+            _container.RemoveChild(lastChild);
+        });
+
+        removeButton.Padding = new Margin(8.0f);
+
+        _buttonContainer.AddChild(addButton);
+        _buttonContainer.AddChild(removeButton);
+
+        var c = new VerticalContainer();
+
+        var m = new MarginContainer();
+        m.AddChild(_container);
+
+        c.AddChild(_buttonContainer);
+        c.AddChild(m);
+
+        _rootFill.AddChild(c);
+
+        _uiSystem.AddElement(_rootFill);
     }
 
 
@@ -77,17 +99,6 @@ public class TestGame : Game
             ResourceManager.Reload();
             _particleSystem!.RestartEmitter(_emitterId);
         }
-
-        if (Input.IsActionPressed("accept"))
-        {
-            _container.AddChild(new Label("こんにちは世界！", _defaultFontSet));
-        }
-
-        if (Input.IsActionPressed("cancel") && _container.Children.Count != 0)
-        {
-            var lastChild = _container.Children.Last();
-            _container.RemoveChild(lastChild);
-        }
     }
 
     protected override void Render(double deltaTime)
@@ -146,12 +157,9 @@ public class TestGame : Game
 
     [NotNull] private Label _label;
 
-    private FillContainer _fillContainer = new();
-    private MarginContainer _marginContainer = new(new Margin(32.0f))
+    private FillContainer _rootFill = new();
+    private HorizontalContainer _buttonContainer = new(16)
     {
+        ConfineToContents = true,
     };
-    // private HorizontalContainer _container = new(new Rect(128.0f, 64.0f), new(), 16)
-    // {
-    //     ConfineToContents = true,
-    // };
 }

Voile/Source/UI/Containers/MarginContainer.cs

@@ -32,6 +32,13 @@ public struct Margin
     }
 
     public static Margin Zero => new Margin(0);
+
+    public static Rect operator +(Margin margin, Rect rect) =>
+        new Rect(rect.Width + margin.Left + margin.Right,
+                 rect.Height + margin.Top + margin.Bottom);
+
+    public static Rect operator +(Rect rect, Margin margin) =>
+        margin + rect;
 }
 
 public class MarginContainer : Container
@@ -58,7 +65,10 @@ public class MarginContainer : Container
         base.OnUpdate();
         if (Parent == null) return;
 
-        Size = Parent.Size;
+        if (Size != Parent.Size)
+        {
+            Size = Parent.Size;
+        }
     }
 
     public override void Arrange()

Voile/Source/UI/UISystem.cs

@@ -150,6 +150,8 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
         {
             var element = elements[i];
 
+            // if (!element.ContainsPoint(context.MousePosition)) continue;
+
             if (element is IInputElement inputElement && !inputElement.IgnoreInput)
             {
                 inputElement.Input(context);

Voile/Source/UI/Widgets/Button.cs

@@ -1,6 +1,8 @@
 using System.Numerics;
 using Voile.Input;
 using Voile.Rendering;
+using Voile.Resources;
+using Voile.UI.Containers;
 
 namespace Voile.UI.Widgets;
 
@@ -17,13 +19,42 @@ public enum ButtonState
 /// </summary>
 public class Button : Widget
 {
-    public string Label { get; set; } = "Button";
-    public override Rect MinimumSize => new Rect(Width: 128.0f, Height: 64.0f);
-
-    public Button(string label, Action pressedAction)
+    public string Text
     {
-        Label = label;
+        get => _text; set
+        {
+            _text = value;
+            MarkDirty();
+        }
+    }
+    public override Rect MinimumSize => Padding + _textSize;
+
+    /// <summary>
+    /// <see cref="FontSet"/> to use with this button.
+    /// </summary>
+    public FontSet FontSet { get; set; } = new();
+    public Margin Padding { get; set; } = Margin.Zero;
+
+    public Button(string text, ResourceRef<Font> fontOverride, Action pressedAction)
+    {
+        _text = text;
         _pressedAction = pressedAction;
+
+        FontSet.AddFont(fontOverride);
+
+        MarkDirty();
+        Update();
+    }
+
+    public Button(string text, FontSet fontSet, Action pressedAction)
+    {
+        _text = text;
+        _pressedAction = pressedAction;
+
+        FontSet = fontSet;
+
+        MarkDirty();
+        Update();
     }
 
     public override void Render(RenderSystem renderer, Style style)
@@ -31,17 +62,46 @@ public class Button : Widget
         // TODO: use a button color from style.
         renderer.SetTransform(GlobalPosition, Vector2.Zero);
         renderer.DrawRectangle(new Vector2(MinimumSize.Width, MinimumSize.Height), new Color(0.25f, 0.25f, 0.25f));
+
+        var textPosition = new Vector2(GlobalPosition.X + Padding.Left, GlobalPosition.Y + Padding.Top);
+        renderer.SetTransform(textPosition, Vector2.Zero);
+        renderer.DrawText(_suitableFont, _text, Color.White);
     }
 
     protected override void OnInput(UIInputContext action)
     {
-
+        if (action.MouseReleased && ContainsPoint(action.MousePosition))
+        {
+            _pressedAction?.Invoke();
+        }
     }
 
     protected override void OnUpdate()
     {
-        throw new NotImplementedException();
+        ResourceRef<Font> fontRef = ResourceRef<Font>.Empty();
+        foreach (var c in _text)
+        {
+            if (FontSet.TryGetFontFor(c, out var fallbackFont))
+            {
+                if (fallbackFont != fontRef)
+                {
+                    fontRef = fallbackFont;
+                }
+            }
+        }
+
+        _suitableFont = fontRef;
+
+        var font = _suitableFont.Value;
+        _textSize = font.Measure(_text);
+
+        Size = Padding + _textSize;
     }
 
     private Action _pressedAction;
+
+    private ResourceRef<Font> _suitableFont = ResourceRef<Font>.Empty();
+
+    private string _text = "Hello, World!";
+    private Rect _textSize = Rect.Zero;
 }