Merge FlexContainer, WIP dynamic container resizing.

Voile/Source/UI/Containers/Container.cs

@@ -15,7 +15,15 @@ public abstract class Container : IElement, IParentableElement, IUpdatableElemen
     /// <inheritdoc />
     public Rect MinimumRect { get; set; } = Rect.Zero;
     /// <inheritdoc />
-    public Rect Size { get; set; } = Rect.Zero;
+    public Rect Size
+    {
+        get => _size;
+        set
+        {
+            _size = value;
+            MarkDirty();
+        }
+    }
     /// <inheritdoc />
     public bool Visible { get; set; } = true;
     /// <inheritdoc />
@@ -71,7 +79,7 @@ public abstract class Container : IElement, IParentableElement, IUpdatableElemen
     {
         if (Children.Count == 0)
         {
-            Size = MinimumRect;
+            _size = MinimumRect;
             return;
         }
 
@@ -99,7 +107,7 @@ public abstract class Container : IElement, IParentableElement, IUpdatableElemen
         float finalWidth = MathF.Max(occupiedWidth, MinimumRect.Width);
         float finalHeight = MathF.Max(occupiedHeight, MinimumRect.Height);
 
-        Size = new Rect(finalWidth, finalHeight);
+        MinimumRect = new Rect(finalWidth, finalHeight);
     }
 
     public void AddChild(IElement child)
@@ -135,4 +143,5 @@ public abstract class Container : IElement, IParentableElement, IUpdatableElemen
 
     private List<IElement> _children = new();
     private bool _isDirty;
+    private Rect _size = Rect.Zero;
 }

Voile/Source/UI/Containers/FlexContainer.cs

@@ -0,0 +1,143 @@
+using System.Numerics;
+using Voile.Rendering;
+
+namespace Voile.UI.Containers;
+
+public enum FlexDirection
+{
+    Row,
+    Column
+}
+
+public enum JustifyContent
+{
+    Start,
+    Center,
+    End,
+    SpaceBetween
+}
+
+public enum AlignItems
+{
+    Start,
+    Center,
+    End
+}
+
+public class FlexContainer : Container
+{
+    public FlexDirection Direction { get; set; } = FlexDirection.Row;
+    public JustifyContent Justify { get; set; } = JustifyContent.Start;
+    public AlignItems Align { get; set; } = AlignItems.Start;
+    public bool Wrap { get; set; } = false;
+    public float Gap { get; set; } = 16f;
+
+    public bool DistributeRemainingSpace { get; set; } = false;
+
+    public FlexContainer() : base() { }
+
+    public FlexContainer(Rect minimumSize, List<IElement> children) : base(minimumSize, children) { }
+
+    public override void Arrange()
+    {
+        float containerMainSize = (Direction == FlexDirection.Row) ? Size.Width : Size.Height;
+        float mainPos = (Direction == FlexDirection.Row) ? Position.X : Position.Y;
+        float crossPos = (Direction == FlexDirection.Row) ? Position.Y : Position.X;
+
+        List<List<IElement>> lines = new();
+        List<IElement> currentLine = new();
+        float lineMainSum = 0f;
+        float maxCross = 0f;
+
+        foreach (var child in Children)
+        {
+            Vector2 childSize = GetChildSize(child);
+            float mainSize = GetMainSize(childSize);
+            float crossSize = GetCrossSize(childSize);
+
+            bool wrapLine = Wrap && currentLine.Count > 0 && (lineMainSum + mainSize + Gap > containerMainSize);
+
+            if (wrapLine)
+            {
+                lines.Add(currentLine);
+                currentLine = new();
+                lineMainSum = 0f;
+                maxCross += crossSize + Gap;
+            }
+
+            currentLine.Add(child);
+            lineMainSum += mainSize + (currentLine.Count > 1 ? Gap : 0);
+        }
+
+        if (currentLine.Count > 0)
+        {
+            lines.Add(currentLine);
+        }
+
+        float currentCross = crossPos;
+
+        foreach (var line in lines)
+        {
+            float lineMainLength = line.Sum(child => GetMainSize(GetChildSize(child))) + Gap * (line.Count - 1);
+            float justifyOffset = GetJustifyOffset(containerMainSize, lineMainLength, line.Count);
+
+            float currentMain = mainPos + justifyOffset;
+            float maxLineCross = line.Select(child => GetCrossSize(GetChildSize(child))).Max();
+
+            foreach (var child in line)
+            {
+                Vector2 childSize = GetChildSize(child);
+
+                float alignedCross = currentCross + GetAlignOffset(maxLineCross, GetCrossSize(childSize));
+
+                Vector2 childPos = (Direction == FlexDirection.Row)
+                    ? new Vector2(currentMain, alignedCross)
+                    : new Vector2(alignedCross, currentMain);
+
+                child.Position = childPos;
+
+                currentMain += GetMainSize(childSize) + Gap;
+            }
+
+            currentCross += maxLineCross + Gap;
+        }
+    }
+
+    private Vector2 GetChildSize(IElement child)
+    {
+        if (child is IResizeableElement resizeable)
+            return new Vector2(resizeable.MinimumRect.Width, resizeable.MinimumRect.Height);
+        return new Vector2(child.Size.Width, child.Size.Height);
+    }
+
+    private float GetMainSize(Vector2 size)
+    {
+        return Direction == FlexDirection.Row ? size.X : size.Y;
+    }
+
+    private float GetCrossSize(Vector2 size)
+    {
+        return Direction == FlexDirection.Row ? size.Y : size.X;
+    }
+
+    private float GetJustifyOffset(float containerSize, float totalMain, int itemCount)
+    {
+        return Justify switch
+        {
+            JustifyContent.Center => (containerSize - totalMain) / 2f,
+            JustifyContent.End => containerSize - totalMain,
+            JustifyContent.SpaceBetween => (itemCount > 1) ? 0 : (containerSize - totalMain) / 2f,
+            _ => 0
+        };
+    }
+
+    private float GetAlignOffset(float maxCross, float childCross)
+    {
+        return Align switch
+        {
+            AlignItems.Center => (maxCross - childCross) / 2f,
+            AlignItems.End => maxCross - childCross,
+            _ => 0f
+        };
+    }
+}