From c18adaeedee9a51714628c2ef4d80490ff482f9b Mon Sep 17 00:00:00 2001
From: dnesov <contact.dnesov@gmail.com>
Date: Sun, 29 Jun 2025 19:22:14 +0200
Subject: [PATCH] Element styling, rename IsMousePressed to
 IsMouseButtonPressed in InputSystem, Button widget.

---
 TestGame/TestGame.cs                          |  33 +++---
 Voile/Source/Input/InputAction.cs             |   2 +-
 Voile/Source/Input/InputSystem.cs             |   2 +-
 Voile/Source/Input/RaylibInputSystem.cs       |   2 +-
 Voile/Source/UI/Containers/Container.cs       |  16 ++-
 Voile/Source/UI/Containers/FillContainer.cs   |   5 +
 Voile/Source/UI/Containers/MarginContainer.cs |  21 +++-
 Voile/Source/UI/Style.cs                      | 101 ++++++++++++++++++
 Voile/Source/UI/UIElement.cs                  |  48 +++++++++
 Voile/Source/UI/UISystem.cs                   |  26 +++--
 Voile/Source/UI/Widgets/Button.cs             |  71 ++++++++++--
 Voile/Source/UI/Widgets/Label.cs              |   4 +-
 Voile/Source/UI/Widgets/Widget.cs             |   5 +-
 13 files changed, 296 insertions(+), 40 deletions(-)

diff --git a/TestGame/TestGame.cs b/TestGame/TestGame.cs
index 455f1aa..81984aa 100644
--- a/TestGame/TestGame.cs
+++ b/TestGame/TestGame.cs
@@ -19,7 +19,7 @@ public class TestGame : Game
     {
         InitializeSystemsDefault();
 
-        _uiSystem = new UISystem(Input, ResourceRef<Style>.Empty());
+        _uiSystem = new UISystem(Input, StyleSheet.Default);
         // _uiSystem.RenderDebugRects = true;
 
         _particleSystem = new ParticleSystem();
@@ -64,7 +64,6 @@ public class TestGame : Game
         _emitterId = _particleSystem.CreateEmitter(Renderer.WindowSize / 2, _fireEffect);
 
         var addButton = new Button("Add element", _defaultFontSet, () => { _container.AddChild(new Label("Hello, World!", _defaultFontSet)); });
-        addButton.Padding = new Margin(8.0f);
 
         var removeButton = new Button("Remove element", _defaultFontSet, () =>
         {
@@ -73,21 +72,30 @@ public class TestGame : Game
             _container.RemoveChild(lastChild);
         });
 
-        removeButton.Padding = new Margin(8.0f);
+        removeButton.StyleVariant = "Danger";
 
-        _buttonContainer.AddChild(addButton);
-        _buttonContainer.AddChild(removeButton);
+        // _buttonContainer.AddChild(addButton);
+        // _buttonContainer.AddChild(removeButton);
 
-        var c = new VerticalContainer();
+        var c = new HorizontalContainer()
+        {
+            StyleVariant = "Layer01",
+            ConfineToContents = true,
+            Anchor = Anchor.TopCenter
+        };
 
-        var m = new MarginContainer();
-        m.AddChild(_container);
+        c.AddChild(addButton);
+        c.AddChild(removeButton);
 
-        c.AddChild(_buttonContainer);
-        c.AddChild(m);
+        var vc = new VerticalContainer(0.0f);
+        vc.AddChild(c);
 
-        _rootFill.AddChild(c);
+        var f = new MarginContainer(new Margin(0.0f));
+        f.AddChild(_container);
 
+        vc.AddChild(f);
+
+        _rootFill.AddChild(vc);
         _uiSystem.AddElement(_rootFill);
     }
 
@@ -152,7 +160,8 @@ public class TestGame : Game
         Justify = JustifyContent.Start,
         Align = AlignItems.Center,
         Wrap = true,
-        Gap = 8.0f
+        Gap = 8.0f,
+        StyleVariant = "Layer02",
     };
 
     [NotNull] private Label _label;
diff --git a/Voile/Source/Input/InputAction.cs b/Voile/Source/Input/InputAction.cs
index 45e7ed1..c1f617a 100644
--- a/Voile/Source/Input/InputAction.cs
+++ b/Voile/Source/Input/InputAction.cs
@@ -45,7 +45,7 @@ namespace Voile.Input
 
         public bool IsPressed(InputSystem inputSystem)
         {
-            return inputSystem.IsMousePressed(MouseButton);
+            return inputSystem.IsMouseButtonPressed(MouseButton);
         }
 
         public bool IsDown(InputSystem inputSystem)
diff --git a/Voile/Source/Input/InputSystem.cs b/Voile/Source/Input/InputSystem.cs
index 87ccce6..5683338 100644
--- a/Voile/Source/Input/InputSystem.cs
+++ b/Voile/Source/Input/InputSystem.cs
@@ -108,7 +108,7 @@ namespace Voile.Input
 
         public abstract int GetCharPressed();
 
-        public abstract bool IsMousePressed(MouseButton button);
+        public abstract bool IsMouseButtonPressed(MouseButton button);
         public abstract bool IsMouseButtonDown(MouseButton button);
         public abstract bool IsMouseButtonReleased(MouseButton button);
         public abstract float GetMouseWheelMovement();
diff --git a/Voile/Source/Input/RaylibInputSystem.cs b/Voile/Source/Input/RaylibInputSystem.cs
index 58aa7e3..b383f97 100644
--- a/Voile/Source/Input/RaylibInputSystem.cs
+++ b/Voile/Source/Input/RaylibInputSystem.cs
@@ -50,7 +50,7 @@ namespace Voile.Input
         public override bool KeyboardKeyJustPressed(KeyboardKey key) => _justPressedKeys.Contains(key);
         public override bool KeyboardKeyJustReleased(KeyboardKey key) => _justReleasedKeys.Contains(key);
 
-        public override bool IsMousePressed(MouseButton button) => _pressedMouseButtons.Contains(button);
+        public override bool IsMouseButtonPressed(MouseButton button) => _pressedMouseButtons.Contains(button);
         public override bool IsMouseButtonReleased(MouseButton button) => _releasedMouseButtons.Contains(button);
         public override bool IsMouseButtonDown(MouseButton button) => _downMouseButtons.Contains(button);
 
diff --git a/Voile/Source/UI/Containers/Container.cs b/Voile/Source/UI/Containers/Container.cs
index b5db935..11f3e3b 100644
--- a/Voile/Source/UI/Containers/Container.cs
+++ b/Voile/Source/UI/Containers/Container.cs
@@ -16,6 +16,8 @@ public abstract class Container : UIElement, IParentableElement
     /// </summary>
     public bool ConfineToContents { get; set; } = false;
 
+    public override string? StyleElementName => nameof(Container);
+
     public override Rect MinimumSize => _minimumSize;
 
     public Container()
@@ -122,6 +124,7 @@ public abstract class Container : UIElement, IParentableElement
 
     public void AddChild(UIElement child)
     {
+        // child.StyleSheetOverride = StyleSheet;
         _children.Add(child);
         child.SetParent(this);
 
@@ -139,10 +142,21 @@ public abstract class Container : UIElement, IParentableElement
 
     public override void Render(RenderSystem renderer, Style style)
     {
+        var backgroundColor = style.BackgroundColor;
+
+        renderer.SetTransform(GlobalPosition, Vector2.Zero);
+        renderer.DrawRectangle(new Vector2(Size.Width, Size.Height), backgroundColor);
+
         foreach (var child in Children)
         {
             if (child is not IRenderableElement renderable) continue;
-            renderable.Render(renderer, style);
+
+            if (!child.TryGetStyle(StyleSheet, out var childStyle))
+            {
+                childStyle = new Style();
+            }
+
+            renderable.Render(renderer, childStyle);
         }
     }
 
diff --git a/Voile/Source/UI/Containers/FillContainer.cs b/Voile/Source/UI/Containers/FillContainer.cs
index 1a08b85..2365bf6 100644
--- a/Voile/Source/UI/Containers/FillContainer.cs
+++ b/Voile/Source/UI/Containers/FillContainer.cs
@@ -52,6 +52,11 @@ public class FillContainer : Container
     {
         base.OnUpdate();
         Size = _lastParentSize;
+
+        if (Children.Count != 0)
+        {
+            Children[0].Size = Size;
+        }
     }
 
     private Rect _lastParentSize = Rect.Zero;
diff --git a/Voile/Source/UI/Containers/MarginContainer.cs b/Voile/Source/UI/Containers/MarginContainer.cs
index 234721f..764a546 100644
--- a/Voile/Source/UI/Containers/MarginContainer.cs
+++ b/Voile/Source/UI/Containers/MarginContainer.cs
@@ -5,7 +5,7 @@ namespace Voile.UI.Containers;
 /// <summary>
 /// Represents the margin offsets applied around an element.
 /// </summary>
-public struct Margin
+public struct Margin : IEquatable<Margin>
 {
     public float Left;
     public float Right;
@@ -39,6 +39,25 @@ public struct Margin
 
     public static Rect operator +(Rect rect, Margin margin) =>
         margin + rect;
+
+
+    public static bool operator ==(Margin a, Margin b) =>
+a.Equals(b);
+
+    public static bool operator !=(Margin a, Margin b) =>
+        !a.Equals(b);
+
+    public bool Equals(Margin other) =>
+        Left == other.Left &&
+        Right == other.Right &&
+        Top == other.Top &&
+        Bottom == other.Bottom;
+
+    public override bool Equals(object? obj) =>
+        obj is Margin other && Equals(other);
+
+    public override int GetHashCode() =>
+        HashCode.Combine(Left, Right, Top, Bottom);
 }
 
 public class MarginContainer : Container
diff --git a/Voile/Source/UI/Style.cs b/Voile/Source/UI/Style.cs
index 81795a4..8a409f6 100644
--- a/Voile/Source/UI/Style.cs
+++ b/Voile/Source/UI/Style.cs
@@ -1,4 +1,6 @@
+using System.Diagnostics.CodeAnalysis;
 using Voile.Resources;
+using Voile.UI.Containers;
 
 namespace Voile.UI;
 
@@ -10,4 +12,103 @@ public class Style : TextDataResource
     public Style(string path) : base(path)
     {
     }
+
+    public Style() : base(string.Empty) { }
+
+    public Margin Padding { get; set; }
+    public Color BackgroundColor { get; set; }
+    public Margin BorderSize { get; set; }
+    public Color BorderColor { get; set; }
+    public float CornerRadius { get; set; }
+    public Color TextColor { get; set; } = Color.White;
+}
+
+public class StyleSheet : TextDataResource
+{
+    public StyleSheet(string path) : base(path)
+    {
+    }
+
+    public StyleSheet(Dictionary<string, Style> styles) : base(string.Empty)
+    {
+        _styles = styles;
+    }
+
+    public bool TryGet(string styleName, [NotNullWhen(true)] out Style? style)
+    {
+        return _styles.TryGetValue(styleName, out style);
+    }
+
+    public static StyleSheet Default => new(new Dictionary<string, Style>()
+    {
+        {"Label", new Style()
+        {
+            TextColor = Color.FromHexString("#161616"),
+        }},
+        { "Button", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#0f62fe"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Button.Normal", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#0f62fe"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Button.Hovered", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#0353e9"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Button.Pressed", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#002d9c"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Button.Danger", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#da1e28"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Button.Danger.Normal", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#da1e28"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Button.Danger.Hovered", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#ba1b23"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Button.Danger.Pressed", new Style()
+        {
+            Padding = new Margin(8.0f),
+            BackgroundColor = Color.FromHexString("#750e13"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Container", new Style()
+        {
+            BackgroundColor = Color.FromHexString("#ffffff"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Container.Layer01", new Style()
+        {
+            BackgroundColor = Color.FromHexString("#f4f4f4"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+        {"Container.Layer02", new Style()
+        {
+            BackgroundColor = Color.FromHexString("#e8e8e8"),
+            TextColor = Color.FromHexString("#ffffff"),
+        }},
+    });
+
+    private Dictionary<string, Style> _styles = new();
 }
\ No newline at end of file
diff --git a/Voile/Source/UI/UIElement.cs b/Voile/Source/UI/UIElement.cs
index 0b7fc09..477a51c 100644
--- a/Voile/Source/UI/UIElement.cs
+++ b/Voile/Source/UI/UIElement.cs
@@ -1,4 +1,6 @@
+using System.Diagnostics.CodeAnalysis;
 using System.Numerics;
+using System.Text;
 using Voile.Rendering;
 
 namespace Voile.UI;
@@ -13,6 +15,23 @@ public abstract class UIElement : IElement, IRenderableElement, IResizeableEleme
     public Vector2 LocalPosition { get; set; } = Vector2.Zero;
     public Vector2 GlobalPosition => _parent?.GlobalPosition + LocalPosition ?? LocalPosition;
 
+    public string StyleName => $"{StyleElementName ?? "UIElement"}{GetStyleVariantString()}{ConstructStyleModifiers(StyleModifiers)}";
+
+    /// <summary>
+    /// An element name for style.
+    /// </summary>
+    public virtual string? StyleElementName { get; }
+
+    public string StyleVariant { get; set; } = string.Empty;
+
+    /// <summary>
+    /// List of style modifiers for this <see cref="UIElement"/>.
+    /// </summary>
+    public virtual string[]? StyleModifiers { get; }
+
+    public StyleSheet StyleSheet => Parent?.StyleSheet ?? StyleSheetOverride;
+    public StyleSheet StyleSheetOverride { get; set; } = new(string.Empty);
+
     /// <summary>
     /// Parent <see cref="UIElement"/> of this element.
     /// </summary>
@@ -47,6 +66,11 @@ public abstract class UIElement : IElement, IRenderableElement, IResizeableEleme
     public abstract Rect MinimumSize { get; }
     public bool Dirty => _dirty;
 
+    public bool TryGetStyle(StyleSheet styleSheet, [NotNullWhen(true)] out Style? style)
+    {
+        return styleSheet.TryGet(StyleName, out style);
+    }
+
     public virtual void MarkDirty()
     {
         if (Parent != null && !Parent.Dirty)
@@ -112,6 +136,30 @@ public abstract class UIElement : IElement, IRenderableElement, IResizeableEleme
         LocalPosition = Anchor.Calculate(parentPosition, parentRect, Size) + new Vector2(AnchorOffset.X, AnchorOffset.Y);
     }
 
+    private string ConstructStyleModifiers(string[]? modifiers)
+    {
+        if (modifiers == null)
+        {
+            return string.Empty;
+        }
+
+        var sb = new StringBuilder();
+        foreach (var modifier in modifiers)
+        {
+            sb.Append($".{modifier}");
+        }
+
+        return sb.ToString();
+    }
+
+    private string GetStyleVariantString()
+    {
+        if (string.IsNullOrEmpty(StyleVariant))
+            return string.Empty;
+
+        return $".{StyleVariant}";
+    }
+
     private bool _dirty = true;
     private Rect _size = Rect.Zero;
 
diff --git a/Voile/Source/UI/UISystem.cs b/Voile/Source/UI/UISystem.cs
index 1644be4..5aa8dc6 100644
--- a/Voile/Source/UI/UISystem.cs
+++ b/Voile/Source/UI/UISystem.cs
@@ -14,25 +14,26 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
 
     public UISystem(InputSystem inputSystem)
     {
-        _style = ResourceRef<Style>.Empty();
+        _styleSheet = StyleSheet.Default;
         _input = inputSystem;
     }
 
-    public UISystem(InputSystem inputSystem, ResourceRef<Style> style)
+    public UISystem(InputSystem inputSystem, StyleSheet styleSheet)
     {
         _input = inputSystem;
-        _style = style;
+        _styleSheet = styleSheet;
     }
 
-    public UISystem(InputSystem inputSystem, ResourceRef<Style> style, List<UIElement> elements)
+    public UISystem(InputSystem inputSystem, StyleSheet styleSheet, List<UIElement> elements)
     {
         _input = inputSystem;
-        _style = style;
+        _styleSheet = styleSheet;
         _elements = elements;
     }
 
     public void AddElement(UIElement element)
     {
+        element.StyleSheetOverride = _styleSheet;
         _elements.Add(element);
         _inputElementIndices.Add(element.GlobalPosition, _elements.Count - 1);
     }
@@ -40,30 +41,33 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
 
     public void Update(double deltaTime)
     {
-        HandleInput();
+        // HandleInput();
     }
 
     public void Render(RenderSystem renderer)
     {
         // Update elements each time UI system is rendered.
+        HandleInput();
+
         foreach (var element in _elements)
         {
             if (element is not IUpdatableElement updatable) continue;
             updatable.Update();
         }
 
+
         foreach (var element in _elements)
         {
             if (element is IRenderableElement renderable)
             {
                 // TODO: normally you'd load a default style if the one supplied is empty,
                 // but for now this will do.
-                if (!_style.TryGetValue(out var value))
+                if (!_styleSheet.TryGet(element.StyleName, out var style))
                 {
-                    value = new Style(string.Empty);
+                    style = new Style(string.Empty);
                 }
 
-                renderable.Render(renderer, value);
+                renderable.Render(renderer, style);
             }
         }
 
@@ -138,7 +142,7 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
             {
                 MouseDown = _input.IsMouseButtonDown(MouseButton.Left),
                 MouseReleased = _input.IsMouseButtonReleased(MouseButton.Left),
-                MousePressed = _input.IsMouseButtonReleased(MouseButton.Left),
+                MousePressed = _input.IsMouseButtonPressed(MouseButton.Left),
             };
             PropagateInput(_elements, context);
         }
@@ -169,7 +173,7 @@ public class UISystem : IUpdatableSystem, IRenderableSystem
         return false;
     }
 
-    private ResourceRef<Style> _style;
+    private StyleSheet _styleSheet;
     private List<UIElement> _elements = new();
     private InputSystem _input;
 
diff --git a/Voile/Source/UI/Widgets/Button.cs b/Voile/Source/UI/Widgets/Button.cs
index 4485543..ec28466 100644
--- a/Voile/Source/UI/Widgets/Button.cs
+++ b/Voile/Source/UI/Widgets/Button.cs
@@ -1,5 +1,4 @@
 using System.Numerics;
-using Voile.Input;
 using Voile.Rendering;
 using Voile.Resources;
 using Voile.UI.Containers;
@@ -27,13 +26,28 @@ public class Button : Widget
             MarkDirty();
         }
     }
+
+    public ButtonState CurrentState { get; private set; } = ButtonState.Normal;
+
     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 Margin Padding
+    {
+        get => _padding; set
+        {
+            _padding = value;
+        }
+    }
+
+    public override string? StyleElementName => nameof(Button);
+    public override string[]? StyleModifiers =>
+    [
+        CurrentState.ToString()
+    ];
 
     public Button(string text, ResourceRef<Font> fontOverride, Action pressedAction)
     {
@@ -60,19 +74,58 @@ public class Button : Widget
     public override void Render(RenderSystem renderer, Style style)
     {
         // TODO: use a button color from style.
+
+        var backgroundColor = style.BackgroundColor;
+
+        if (_padding != style.Padding)
+        {
+            MarkDirty();
+        }
+
+        _padding = style.Padding;
+        var textColor = style.TextColor;
+
         renderer.SetTransform(GlobalPosition, Vector2.Zero);
-        renderer.DrawRectangle(new Vector2(MinimumSize.Width, MinimumSize.Height), new Color(0.25f, 0.25f, 0.25f));
+        renderer.DrawRectangle(new Vector2(Size.Width, Size.Height), backgroundColor);
 
         var textPosition = new Vector2(GlobalPosition.X + Padding.Left, GlobalPosition.Y + Padding.Top);
         renderer.SetTransform(textPosition, Vector2.Zero);
-        renderer.DrawText(_suitableFont, _text, Color.White);
+        renderer.DrawText(_suitableFont, _text, textColor);
     }
 
     protected override void OnInput(UIInputContext action)
     {
-        if (action.MouseReleased && ContainsPoint(action.MousePosition))
+        bool isHovering = ContainsPoint(action.MousePosition);
+
+        if (action.MousePressed && isHovering)
         {
-            _pressedAction?.Invoke();
+            _isHeldDown = true;
+            CurrentState = ButtonState.Pressed;
+        }
+        else if (action.MouseReleased)
+        {
+            if (_isHeldDown && isHovering)
+            {
+                _pressedAction?.Invoke();
+            }
+
+            _isHeldDown = false;
+            CurrentState = isHovering ? ButtonState.Hovered : ButtonState.Normal;
+        }
+        else
+        {
+            if (_isHeldDown)
+            {
+                CurrentState = ButtonState.Pressed; // keep showing as pressed
+            }
+            else if (isHovering)
+            {
+                CurrentState = ButtonState.Hovered;
+            }
+            else
+            {
+                CurrentState = ButtonState.Normal;
+            }
         }
     }
 
@@ -95,7 +148,7 @@ public class Button : Widget
         var font = _suitableFont.Value;
         _textSize = font.Measure(_text);
 
-        Size = Padding + _textSize;
+        Size = _padding + _textSize;
     }
 
     private Action _pressedAction;
@@ -104,4 +157,8 @@ public class Button : Widget
 
     private string _text = "Hello, World!";
     private Rect _textSize = Rect.Zero;
+
+    private Margin _padding;
+
+    private bool _isHeldDown;
 }
\ No newline at end of file
diff --git a/Voile/Source/UI/Widgets/Label.cs b/Voile/Source/UI/Widgets/Label.cs
index 449e79f..ae04d5f 100644
--- a/Voile/Source/UI/Widgets/Label.cs
+++ b/Voile/Source/UI/Widgets/Label.cs
@@ -18,6 +18,8 @@ public class Label : Widget
         }
     }
 
+    public override string? StyleElementName => nameof(Label);
+
     /// <summary>
     /// <see cref="FontSet"/> to use with this label.
     /// </summary>
@@ -53,7 +55,7 @@ public class Label : Widget
         // TODO: use style here.
 
         renderer.SetTransform(GlobalPosition, Vector2.Zero);
-        renderer.DrawText(_suitableFont, _text, Color.White);
+        renderer.DrawText(_suitableFont, _text, style.TextColor);
     }
 
     protected override void OnUpdate()
diff --git a/Voile/Source/UI/Widgets/Widget.cs b/Voile/Source/UI/Widgets/Widget.cs
index 2ee9006..1ff1ae2 100644
--- a/Voile/Source/UI/Widgets/Widget.cs
+++ b/Voile/Source/UI/Widgets/Widget.cs
@@ -29,10 +29,7 @@ public abstract class Widget : UIElement, IInputElement
     public void Input(UIInputContext context)
     {
         if (context.Handled || IgnoreInput) return;
-        if (ContainsPoint(context.MousePosition))
-        {
-            OnInput(context);
-        }
+        OnInput(context);
     }
 
     /// <summary>