Merge commit '7621e2f8dec938cf48181c8b10afc9b01f444e68' into beta

submodules/ComponentFlow/Source/Components/Button.swift

@@ -0,0 +1,341 @@
+import Foundation
+import UIKit
+
+public final class Button: Component {
+    public let content: AnyComponent<Empty>
+    public let minSize: CGSize?
+    public let hitTestEdgeInsets: UIEdgeInsets?
+    public let tag: AnyObject?
+    public let automaticHighlight: Bool
+    public let isEnabled: Bool
+    public let isExclusive: Bool
+    public let action: () -> Void
+    public let holdAction: ((UIView) -> Void)?
+    public let highlightedAction: ActionSlot<Bool>?
+
+    convenience public init(
+        content: AnyComponent<Empty>,
+        isEnabled: Bool = true,
+        automaticHighlight: Bool = true,
+        action: @escaping () -> Void,
+        highlightedAction: ActionSlot<Bool>? = nil
+    ) {
+        self.init(
+            content: content,
+            minSize: nil,
+            hitTestEdgeInsets: nil,
+            tag: nil,
+            automaticHighlight: automaticHighlight,
+            isEnabled: isEnabled,
+            action: action,
+            holdAction: nil,
+            highlightedAction: highlightedAction
+        )
+    }
+    
+    private init(
+        content: AnyComponent<Empty>,
+        minSize: CGSize? = nil,
+        hitTestEdgeInsets: UIEdgeInsets? = nil,
+        tag: AnyObject? = nil,
+        automaticHighlight: Bool = true,
+        isEnabled: Bool = true,
+        isExclusive: Bool = true,
+        action: @escaping () -> Void,
+        holdAction: ((UIView) -> Void)?,
+        highlightedAction: ActionSlot<Bool>?
+    ) {
+        self.content = content
+        self.minSize = minSize
+        self.hitTestEdgeInsets = hitTestEdgeInsets
+        self.tag = tag
+        self.automaticHighlight = automaticHighlight
+        self.isEnabled = isEnabled
+        self.isExclusive = isExclusive
+        self.action = action
+        self.holdAction = holdAction
+        self.highlightedAction = highlightedAction
+    }
+    
+    public func minSize(_ minSize: CGSize?) -> Button {
+        return Button(
+            content: self.content,
+            minSize: minSize,
+            hitTestEdgeInsets: self.hitTestEdgeInsets,
+            tag: self.tag,
+            automaticHighlight: self.automaticHighlight,
+            isEnabled: self.isEnabled,
+            isExclusive: self.isExclusive,
+            action: self.action,
+            holdAction: self.holdAction,
+            highlightedAction: self.highlightedAction
+        )
+    }
+    
+    public func withHitTestEdgeInsets(_ hitTestEdgeInsets: UIEdgeInsets?) -> Button {
+        return Button(
+            content: self.content,
+            minSize: self.minSize,
+            hitTestEdgeInsets: hitTestEdgeInsets,
+            tag: self.tag,
+            automaticHighlight: self.automaticHighlight,
+            isEnabled: self.isEnabled,
+            isExclusive: self.isExclusive,
+            action: self.action,
+            holdAction: self.holdAction,
+            highlightedAction: self.highlightedAction
+        )
+    }
+    
+    public func withIsExclusive(_ isExclusive: Bool) -> Button {
+        return Button(
+            content: self.content,
+            minSize: self.minSize,
+            hitTestEdgeInsets: self.hitTestEdgeInsets,
+            tag: self.tag,
+            automaticHighlight: self.automaticHighlight,
+            isEnabled: self.isEnabled,
+            isExclusive: isExclusive,
+            action: self.action,
+            holdAction: self.holdAction,
+            highlightedAction: self.highlightedAction
+        )
+    }
+    
+    
+    public func withHoldAction(_ holdAction: ((UIView) -> Void)?) -> Button {
+        return Button(
+            content: self.content,
+            minSize: self.minSize,
+            hitTestEdgeInsets: self.hitTestEdgeInsets,
+            tag: self.tag,
+            automaticHighlight: self.automaticHighlight,
+            isEnabled: self.isEnabled,
+            isExclusive: self.isExclusive,
+            action: self.action,
+            holdAction: holdAction,
+            highlightedAction: self.highlightedAction
+        )
+    }
+    
+    public func tagged(_ tag: AnyObject) -> Button {
+        return Button(
+            content: self.content,
+            minSize: self.minSize,
+            hitTestEdgeInsets: self.hitTestEdgeInsets,
+            tag: tag,
+            automaticHighlight: self.automaticHighlight,
+            isEnabled: self.isEnabled,
+            isExclusive: self.isExclusive,
+            action: self.action,
+            holdAction: self.holdAction,
+            highlightedAction: self.highlightedAction
+        )
+    }
+    
+    public static func ==(lhs: Button, rhs: Button) -> Bool {
+        if lhs.content != rhs.content {
+            return false
+        }
+        if lhs.minSize != rhs.minSize {
+            return false
+        }
+        if lhs.hitTestEdgeInsets != rhs.hitTestEdgeInsets {
+            return false
+        }
+        if lhs.tag !== rhs.tag {
+            return false
+        }
+        if lhs.automaticHighlight != rhs.automaticHighlight {
+            return false
+        }
+        if lhs.isEnabled != rhs.isEnabled {
+            return false
+        }
+        if lhs.isExclusive != rhs.isExclusive {
+            return false
+        }
+        return true
+    }
+    
+    public final class View: UIButton, ComponentTaggedView {
+        private let contentView: ComponentHostView<Empty>
+        
+        public var content: UIView? {
+            return self.contentView.componentView
+        }
+        
+        private var component: Button?
+        private var currentIsHighlighted: Bool = false {
+            didSet {
+                guard let component = self.component else {
+                    return
+                }
+                if self.currentIsHighlighted != oldValue {
+                    if component.automaticHighlight {
+                        self.updateAlpha(transition: .immediate)
+                    }
+                    component.highlightedAction?.invoke(self.currentIsHighlighted)
+                }
+            }
+        }
+        
+        private func updateAlpha(transition: ComponentTransition) {
+            guard let component = self.component else {
+                return
+            }
+            let alpha: CGFloat
+            if component.isEnabled {
+                if component.automaticHighlight {
+                    alpha = self.currentIsHighlighted ? 0.6 : 1.0
+                } else {
+                    alpha = 1.0
+                }
+            } else {
+                alpha = 0.3
+            }
+            transition.setAlpha(view: self.contentView, alpha: alpha)
+        }
+        
+        private var holdActionTriggerred: Bool = false
+        private var holdActionTimer: Timer?
+        
+        public override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
+            var bounds = self.bounds
+            if let hitTestEdgeInsets = self.component?.hitTestEdgeInsets {
+                bounds = bounds.insetBy(dx: hitTestEdgeInsets.left, dy: hitTestEdgeInsets.top)
+            }
+            return bounds.contains(point)
+        }
+        
+        override init(frame: CGRect) {
+            self.contentView = ComponentHostView<Empty>()
+            self.contentView.isUserInteractionEnabled = false
+            self.contentView.layer.allowsGroupOpacity = true
+            
+            super.init(frame: frame)
+            
+            self.addSubview(self.contentView)
+            
+            self.addTarget(self, action: #selector(self.pressed), for: .touchUpInside)
+        }
+        
+        required init?(coder: NSCoder) {
+            fatalError("init(coder:) has not been implemented")
+        }
+        
+        deinit {
+            self.holdActionTimer?.invalidate()
+        }
+        
+        public func matches(tag: Any) -> Bool {
+            if let component = self.component, let componentTag = component.tag {
+                let tag = tag as AnyObject
+                if componentTag === tag {
+                    return true
+                }
+            }
+            return false
+        }
+        
+        @objc private func pressed() {
+            if self.holdActionTriggerred {
+                self.holdActionTriggerred = false
+            } else {
+                self.component?.action()
+            }
+        }
+        
+        override public func beginTracking(_ touch: UITouch, with event: UIEvent?) -> Bool {
+            self.currentIsHighlighted = true
+            
+            self.holdActionTriggerred = false
+            
+            if self.component?.holdAction != nil {
+                self.holdActionTriggerred = true
+                self.component?.action()
+                
+                self.holdActionTimer?.invalidate()
+                if #available(iOS 10.0, *) {
+                    let holdActionTimer = Timer(timeInterval: 0.5, repeats: false, block: { [weak self] _ in
+                        guard let strongSelf = self else {
+                            return
+                        }
+                        strongSelf.holdActionTimer?.invalidate()
+                        strongSelf.component?.holdAction?(strongSelf)
+                        strongSelf.beginExecuteHoldActionTimer()
+                    })
+                    self.holdActionTimer = holdActionTimer
+                    RunLoop.main.add(holdActionTimer, forMode: .common)
+                }
+            }
+            
+            return super.beginTracking(touch, with: event)
+        }
+        
+        private func beginExecuteHoldActionTimer() {
+            self.holdActionTimer?.invalidate()
+            if #available(iOS 10.0, *) {
+                let holdActionTimer = Timer(timeInterval: 0.1, repeats: true, block: { [weak self] _ in
+                    guard let strongSelf = self else {
+                        return
+                    }
+                    strongSelf.component?.holdAction?(strongSelf)
+                })
+                self.holdActionTimer = holdActionTimer
+                RunLoop.main.add(holdActionTimer, forMode: .common)
+            }
+        }
+        
+        override public func endTracking(_ touch: UITouch?, with event: UIEvent?) {
+            self.currentIsHighlighted = false
+            
+            self.holdActionTimer?.invalidate()
+            self.holdActionTimer = nil
+            
+            super.endTracking(touch, with: event)
+        }
+        
+        override public func cancelTracking(with event: UIEvent?) {
+            self.currentIsHighlighted = false
+            
+            self.holdActionTimer?.invalidate()
+            self.holdActionTimer = nil
+            
+            super.cancelTracking(with: event)
+        }
+        
+        func update(component: Button, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+            let contentSize = self.contentView.update(
+                transition: transition,
+                component: component.content,
+                environment: {},
+                containerSize: availableSize
+            )
+            
+            var size = contentSize
+            if let minSize = component.minSize {
+                size.width = max(size.width, minSize.width)
+                size.height = max(size.height, minSize.height)
+            }
+            
+            self.component = component
+            
+            self.updateAlpha(transition: transition)
+            self.isEnabled = component.isEnabled
+            self.isExclusiveTouch = component.isExclusive
+            
+            transition.setFrame(view: self.contentView, frame: CGRect(origin: CGPoint(x: floor((size.width - contentSize.width) / 2.0), y: floor((size.height - contentSize.height) / 2.0)), size: contentSize), completion: nil)
+            
+            return size
+        }
+    }
+    
+    public func makeView() -> View {
+        return View(frame: CGRect())
+    }
+    
+    public func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+        view.update(component: self, availableSize: availableSize, state: state, environment: environment, transition: transition)
+    }
+}

submodules/ComponentFlow/Source/Components/Circle.swift

@@ -0,0 +1,69 @@
+import Foundation
+import UIKit
+
+public final class Circle: Component {
+    public let fillColor: UIColor
+    public let strokeColor: UIColor
+    public let strokeWidth: CGFloat
+    public let size: CGSize
+    
+    public init(fillColor: UIColor = .clear, strokeColor: UIColor = .clear, strokeWidth: CGFloat = 0.0, size: CGSize) {
+        self.fillColor = fillColor
+        self.strokeColor = strokeColor
+        self.strokeWidth = strokeWidth
+        self.size = size
+    }
+
+    public static func ==(lhs: Circle, rhs: Circle) -> Bool {
+        if !lhs.fillColor.isEqual(rhs.fillColor) {
+            return false
+        }
+        if !lhs.strokeColor.isEqual(rhs.strokeColor) {
+            return false
+        }
+        if lhs.strokeWidth != rhs.strokeWidth {
+            return false
+        }
+        if lhs.size != rhs.size {
+            return false
+        }
+        return true
+    }
+    
+    public final class View: UIImageView {
+        var component: Circle?
+        var currentSize: CGSize?
+        
+        func update(component: Circle, availableSize: CGSize, transition: ComponentTransition) -> CGSize {
+            let size = CGSize(width: min(availableSize.width, component.size.width), height: min(availableSize.height, component.size.height))
+            
+            if self.currentSize != size || self.component != component {
+                self.currentSize = size
+                self.component = component
+                
+                UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
+                if let context = UIGraphicsGetCurrentContext() {
+                    context.setFillColor(component.fillColor.cgColor)
+                    context.fillEllipse(in: CGRect(origin: CGPoint(), size: size))
+                    if component.strokeWidth > 0.0 {
+                        context.setStrokeColor(component.strokeColor.cgColor)
+                        context.setLineWidth(component.strokeWidth)
+                        context.strokeEllipse(in: CGRect(origin: CGPoint(), size: size).insetBy(dx: component.strokeWidth / 2.0, dy: component.strokeWidth / 2.0))
+                    }
+                }
+                self.image = UIGraphicsGetImageFromCurrentImageContext()
+                UIGraphicsEndImageContext()
+            }
+
+            return size
+        }
+    }
+    
+    public func makeView() -> View {
+        return View()
+    }
+    
+    public func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+        return view.update(component: self, availableSize: availableSize, transition: transition)
+    }
+}

submodules/ComponentFlow/Source/Components/HStack.swift

@@ -0,0 +1,105 @@
+import Foundation
+import UIKit
+
+public enum HStackAlignment {
+    case left
+    case alternatingLeftRight
+}
+
+public final class HStack<ChildEnvironment: Equatable>: CombinedComponent {
+    public typealias EnvironmentType = ChildEnvironment
+
+    private let items: [AnyComponentWithIdentity<ChildEnvironment>]
+    private let spacing: CGFloat
+    private let alignment: HStackAlignment
+
+    public init(_ items: [AnyComponentWithIdentity<ChildEnvironment>], spacing: CGFloat, alignment: HStackAlignment = .left) {
+        self.items = items
+        self.spacing = spacing
+        self.alignment = alignment
+    }
+
+    public static func ==(lhs: HStack<ChildEnvironment>, rhs: HStack<ChildEnvironment>) -> Bool {
+        if lhs.items != rhs.items {
+            return false
+        }
+        if lhs.spacing != rhs.spacing {
+            return false
+        }
+        if lhs.alignment != rhs.alignment {
+            return false
+        }
+        return true
+    }
+
+    public static var body: Body {
+        let children = ChildMap(environment: ChildEnvironment.self, keyedBy: AnyHashable.self)
+
+        return { context in
+            var remainingWidth: CGFloat = context.availableSize.width
+            var updatedChildren: [_UpdatedChildComponent] = []
+            
+            for item in context.component.items {
+                let child = children[item.id].update(
+                    component: item.component, environment: {
+                        context.environment[ChildEnvironment.self]
+                    },
+                    availableSize: CGSize(width: remainingWidth, height: context.availableSize.height),
+                    transition: context.transition
+                )
+                updatedChildren.append(child)
+                remainingWidth -= context.component.spacing + child.size.width
+            }
+            
+            var size = CGSize(width: 0.0, height: 0.0)
+            switch context.component.alignment {
+            case .left:
+                for child in updatedChildren {
+                    size.width += child.size.width
+                    size.height = max(size.height, child.size.height)
+                }
+                size.width += context.component.spacing * CGFloat(updatedChildren.count - 1)
+                
+                var nextX = 0.0
+                for child in updatedChildren {
+                    context.add(child
+                        .position(child.size.centered(in: CGRect(origin: CGPoint(x: nextX, y: floor((size.height - child.size.height) * 0.5)), size: child.size)).center)
+                        .appear(.default(scale: true, alpha: true))
+                        .disappear(.default(scale: true, alpha: true))
+                    )
+                    nextX += child.size.width
+                    nextX += context.component.spacing
+                }
+            case .alternatingLeftRight:
+                size.width = context.availableSize.width
+                for child in updatedChildren {
+                    size.height = max(size.height, child.size.height)
+                }
+                
+                var nextLeftX = 0.0
+                var nextRightX = size.width
+                for i in 0 ..< updatedChildren.count {
+                    let child = updatedChildren[i]
+                    let childFrame: CGRect
+                    if i % 2 == 0 {
+                        childFrame = CGRect(origin: CGPoint(x: nextLeftX, y: floor((size.height - child.size.height) * 0.5)), size: child.size)
+                        nextLeftX += child.size.width
+                        nextLeftX += context.component.spacing
+                    } else {
+                        childFrame = CGRect(origin: CGPoint(x: nextRightX - child.size.width, y: floor((size.height - child.size.height) * 0.5)), size: child.size)
+                        nextRightX -= child.size.width
+                        nextRightX -= context.component.spacing
+                    }
+                    
+                    context.add(child
+                        .position(child.size.centered(in: childFrame).center)
+                        .appear(.default(scale: true, alpha: true))
+                        .disappear(.default(scale: true, alpha: true))
+                    )
+                }
+            }
+
+            return size
+        }
+    }
+}

submodules/ComponentFlow/Source/Components/Image.swift

@@ -0,0 +1,69 @@
+import Foundation
+import UIKit
+
+public final class Image: Component {
+    public let image: UIImage?
+    public let tintColor: UIColor?
+    public let size: CGSize?
+    public let contentMode: UIImageView.ContentMode
+
+    public init(
+        image: UIImage?,
+        tintColor: UIColor? = nil,
+        size: CGSize? = nil,
+        contentMode: UIImageView.ContentMode = .scaleToFill
+    ) {
+        self.image = image
+        self.tintColor = tintColor
+        self.size = size
+        self.contentMode = contentMode
+    }
+
+    public static func ==(lhs: Image, rhs: Image) -> Bool {
+        if lhs.image !== rhs.image {
+            return false
+        }
+        if lhs.tintColor != rhs.tintColor {
+            return false
+        }
+        if lhs.size != rhs.size {
+            return false
+        }
+        if lhs.contentMode != rhs.contentMode {
+            return false
+        }
+        return true
+    }
+
+    public final class View: UIImageView {
+        init() {
+            super.init(frame: CGRect())
+        }
+
+        required init?(coder aDecoder: NSCoder) {
+            preconditionFailure()
+        }
+
+        func update(component: Image, availableSize: CGSize, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+            self.image = component.image
+            self.contentMode = component.contentMode
+
+            transition.setTintColor(view: self, color: component.tintColor ?? .white)
+            
+            switch component.contentMode {
+            case .center:
+                return component.image?.size ?? availableSize
+            default:
+                return component.size ?? availableSize
+            }
+        }
+    }
+
+    public func makeView() -> View {
+        return View()
+    }
+
+    public func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+        return view.update(component: self, availableSize: availableSize, environment: environment, transition: transition)
+    }
+}

submodules/ComponentFlow/Source/Components/LazyList.swift

@@ -0,0 +1,3 @@
+import Foundation
+import UIKit
+

submodules/ComponentFlow/Source/Components/List.swift

@@ -0,0 +1,92 @@
+import Foundation
+import UIKit
+
+public final class List<ChildEnvironment: Equatable>: CombinedComponent {
+    public enum Direction {
+        case horizontal
+        case vertical
+    }
+    
+    public typealias EnvironmentType = ChildEnvironment
+
+    private let items: [AnyComponentWithIdentity<ChildEnvironment>]
+    private let direction: Direction
+    private let centerAlignment: Bool
+    private let appear: ComponentTransition.Appear
+
+    public init(_ items: [AnyComponentWithIdentity<ChildEnvironment>], direction: Direction = .vertical, centerAlignment: Bool = false, appear: ComponentTransition.Appear = .default()) {
+        self.items = items
+        self.direction = direction
+        self.centerAlignment = centerAlignment
+        self.appear = appear
+    }
+
+    public static func ==(lhs: List<ChildEnvironment>, rhs: List<ChildEnvironment>) -> Bool {
+        if lhs.items != rhs.items {
+            return false
+        }
+        if lhs.direction != rhs.direction {
+            return false
+        }
+        if lhs.centerAlignment != rhs.centerAlignment {
+            return false
+        }
+        return true
+    }
+
+    public static var body: Body {
+        let children = ChildMap(environment: ChildEnvironment.self, keyedBy: AnyHashable.self)
+
+        return { context in
+            let updatedChildren = context.component.items.map { item in
+                return children[item.id].update(
+                    component: item.component, environment: {
+                        context.environment[ChildEnvironment.self]
+                    },
+                    availableSize: context.availableSize,
+                    transition: context.transition
+                )
+            }
+            
+            let maxWidth: CGFloat = updatedChildren.reduce(CGFloat(0.0)) { partialResult, child in
+                return max(partialResult, child.size.width)
+            }
+
+            var nextOrigin: CGFloat = 0.0
+            for child in updatedChildren {
+                let position: CGPoint
+                switch context.component.direction {
+                    case .horizontal:
+                        position = CGPoint(x: nextOrigin + child.size.width / 2.0, y: child.size.height / 2.0)
+                        nextOrigin += child.size.width
+                    case .vertical:
+                        let originX: CGFloat
+                        if context.component.centerAlignment {
+                            originX = maxWidth / 2.0
+                        } else {
+                            originX = child.size.width / 2.0
+                        }
+                        position = CGPoint(x: originX, y: nextOrigin + child.size.height / 2.0)
+                        nextOrigin += child.size.height
+                }
+                context.add(child
+                    .position(position)
+                    .appear(context.component.appear)
+                )
+            }
+
+            switch context.component.direction {
+                case .horizontal:
+                    return CGSize(width: min(context.availableSize.width, nextOrigin), height: context.availableSize.height)
+                case .vertical:
+                    let width: CGFloat
+                    if context.component.centerAlignment {
+                        width = maxWidth
+                    } else {
+                        width = context.availableSize.width
+                    }
+                    return CGSize(width: width, height: min(context.availableSize.height, nextOrigin))
+            }
+        }
+    }
+}

submodules/ComponentFlow/Source/Components/Rectangle.swift

@@ -0,0 +1,70 @@
+import Foundation
+import UIKit
+
+public final class Rectangle: Component {
+    private let color: UIColor
+    private let width: CGFloat?
+    private let height: CGFloat?
+    private let tag: NSObject?
+    
+    public init(color: UIColor, width: CGFloat? = nil, height: CGFloat? = nil, tag: NSObject? = nil) {
+        self.color = color
+        self.width = width
+        self.height = height
+        self.tag = tag
+    }
+
+    public static func ==(lhs: Rectangle, rhs: Rectangle) -> Bool {
+        if !lhs.color.isEqual(rhs.color) {
+            return false
+        }
+        if lhs.width != rhs.width {
+            return false
+        }
+        if lhs.height != rhs.height {
+            return false
+        }
+        return true
+    }
+    
+    public final class View: UIView, ComponentTaggedView {
+        fileprivate var componentTag: NSObject?
+        
+        override public init(frame: CGRect) {
+            super.init(frame: frame)
+        }
+        
+        required public init?(coder: NSCoder) {
+            fatalError("init(coder:) has not been implemented")
+        }
+        
+        public func matches(tag: Any) -> Bool {
+            if let componentTag = self.componentTag {
+                let tag = tag as AnyObject
+                if componentTag === tag {
+                    return true
+                }
+            }
+            return false
+        }
+    }
+    
+    public func makeView() -> View {
+        return View(frame: CGRect())
+    }
+    
+    public func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+        var size = availableSize
+        if let width = self.width {
+            size.width = min(size.width, width)
+        }
+        if let height = self.height {
+            size.height = min(size.height, height)
+        }
+
+        view.backgroundColor = self.color
+        view.componentTag = self.tag
+
+        return size
+    }
+}

submodules/ComponentFlow/Source/Components/RoundedRectangle.swift

@@ -0,0 +1,412 @@
+import Foundation
+import UIKit
+import Display
+
+public final class RoundedRectangle: Component {
+    public enum GradientDirection: Equatable {
+        case horizontal
+        case vertical
+    }
+    
+    public let colors: [UIColor]
+    public let cornerRadius: CGFloat?
+    public let gradientDirection: GradientDirection
+    public let stroke: CGFloat?
+    public let strokeColor: UIColor?
+    public let size: CGSize?
+    
+    public convenience init(color: UIColor, cornerRadius: CGFloat?, stroke: CGFloat? = nil, strokeColor: UIColor? = nil, size: CGSize? = nil) {
+        self.init(colors: [color], cornerRadius: cornerRadius, stroke: stroke, strokeColor: strokeColor, size: size)
+    }
+    
+    public init(colors: [UIColor], cornerRadius: CGFloat?, gradientDirection: GradientDirection = .horizontal, stroke: CGFloat? = nil, strokeColor: UIColor? = nil, size: CGSize? = nil) {
+        self.colors = colors
+        self.cornerRadius = cornerRadius
+        self.gradientDirection = gradientDirection
+        self.stroke = stroke
+        self.strokeColor = strokeColor
+        self.size = size
+    }
+
+    public static func ==(lhs: RoundedRectangle, rhs: RoundedRectangle) -> Bool {
+        if lhs.colors != rhs.colors {
+            return false
+        }
+        if lhs.cornerRadius != rhs.cornerRadius {
+            return false
+        }
+        if lhs.gradientDirection != rhs.gradientDirection {
+            return false
+        }
+        if lhs.stroke != rhs.stroke {
+            return false
+        }
+        if lhs.strokeColor != rhs.strokeColor {
+            return false
+        }
+        if lhs.size != rhs.size {
+            return false
+        }
+        return true
+    }
+    
+    public final class View: UIImageView {
+        var component: RoundedRectangle?
+        
+        func update(component: RoundedRectangle, availableSize: CGSize, transition: ComponentTransition) -> CGSize {
+            let size = component.size ?? availableSize
+            if self.component != component {
+                let cornerRadius = component.cornerRadius ?? min(size.width, size.height) * 0.5
+                
+                if component.colors.count == 1, let color = component.colors.first {
+                    let imageSize = CGSize(width: max(component.stroke ?? 0.0, cornerRadius) * 2.0, height: max(component.stroke ?? 0.0, cornerRadius) * 2.0)
+                    UIGraphicsBeginImageContextWithOptions(imageSize, false, 0.0)
+                    if let context = UIGraphicsGetCurrentContext() {
+                        if let strokeColor = component.strokeColor {
+                            context.setFillColor(strokeColor.cgColor)
+                        } else {
+                            context.setFillColor(color.cgColor)
+                        }
+                        context.fillEllipse(in: CGRect(origin: CGPoint(), size: imageSize))
+                        
+                        if let stroke = component.stroke, stroke > 0.0 {
+                            if let _ = component.strokeColor {
+                                context.setFillColor(color.cgColor)
+                            } else {
+                                context.setBlendMode(.clear)
+                            }
+                            context.fillEllipse(in: CGRect(origin: CGPoint(), size: imageSize).insetBy(dx: stroke, dy: stroke))
+                        }
+                    }
+                    
+                    self.image = UIGraphicsGetImageFromCurrentImageContext()?.stretchableImage(withLeftCapWidth: Int(cornerRadius), topCapHeight: Int(cornerRadius))
+                    UIGraphicsEndImageContext()
+                } else if component.colors.count > 1 {
+                    let imageSize = size
+                    UIGraphicsBeginImageContextWithOptions(imageSize, false, 0.0)
+                    if let context = UIGraphicsGetCurrentContext() {
+                        context.addPath(UIBezierPath(roundedRect: CGRect(origin: CGPoint(), size: imageSize), cornerRadius: cornerRadius).cgPath)
+                        context.clip()
+
+                        let colors = component.colors
+                        let gradientColors = colors.map { $0.cgColor } as CFArray
+                        let colorSpace = CGColorSpaceCreateDeviceRGB()
+                        
+                        var locations: [CGFloat] = []
+                        let delta = 1.0 / CGFloat(colors.count - 1)
+                        for i in 0 ..< colors.count {
+                            locations.append(delta * CGFloat(i))
+                        }
+                        let gradient = CGGradient(colorsSpace: colorSpace, colors: gradientColors, locations: &locations)!
+                        context.drawLinearGradient(gradient, start: CGPoint(x: 0.0, y: 0.0), end: component.gradientDirection == .horizontal ? CGPoint(x: imageSize.width, y: 0.0) : CGPoint(x: 0.0, y: imageSize.height), options: CGGradientDrawingOptions())
+                        
+                        if let stroke = component.stroke, stroke > 0.0 {
+                            context.resetClip()
+                            
+                            context.addPath(UIBezierPath(roundedRect: CGRect(origin: CGPoint(), size: imageSize).insetBy(dx: stroke, dy: stroke), cornerRadius: cornerRadius).cgPath)
+                            context.setBlendMode(.clear)
+                            context.fill(CGRect(origin: .zero, size: imageSize))
+                        }
+                    }
+                    self.image = UIGraphicsGetImageFromCurrentImageContext()?.stretchableImage(withLeftCapWidth: Int(cornerRadius), topCapHeight: Int(cornerRadius))
+                    UIGraphicsEndImageContext()
+                }
+            }
+
+            return size
+        }
+    }
+    
+    public func makeView() -> View {
+        return View()
+    }
+    
+    public func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+        return view.update(component: self, availableSize: availableSize, transition: transition)
+    }
+}
+
+public final class FilledRoundedRectangleComponent: Component {
+    public enum CornerRadius: Equatable {
+        case value(CGFloat)
+        case minEdge
+    }
+    
+    public let color: UIColor
+    public let cornerRadius: CornerRadius
+    public let smoothCorners: Bool
+    
+    public init(
+        color: UIColor,
+        cornerRadius: CornerRadius,
+        smoothCorners: Bool
+    ) {
+        self.color = color
+        self.cornerRadius = cornerRadius
+        self.smoothCorners = smoothCorners
+    }
+    
+    public static func ==(lhs: FilledRoundedRectangleComponent, rhs: FilledRoundedRectangleComponent) -> Bool {
+        if lhs === rhs {
+            return true
+        }
+        if lhs.color != rhs.color {
+            return false
+        }
+        if lhs.cornerRadius != rhs.cornerRadius {
+            return false
+        }
+        if lhs.smoothCorners != rhs.smoothCorners {
+            return false
+        }
+        return true
+    }
+    
+    public final class View: UIImageView {
+        private var component: FilledRoundedRectangleComponent?
+        
+        private var currentCornerRadius: CGFloat?
+        private var cornerImage: UIImage?
+        
+        override init(frame: CGRect) {
+            super.init(frame: frame)
+        }
+        
+        required init?(coder: NSCoder) {
+            fatalError("init(coder:) has not been implemented")
+        }
+        
+        private func applyStaticCornerRadius() {
+            guard let component = self.component else {
+                return
+            }
+            guard let cornerRadius = self.currentCornerRadius else {
+                return
+            }
+            if cornerRadius == 0.0 {
+                if let cornerImage = self.cornerImage, cornerImage.size.width == 1.0 {
+                } else {
+                    self.cornerImage = generateImage(CGSize(width: 1.0, height: 1.0), rotatedContext: { size, context in
+                        context.setFillColor(UIColor.white.cgColor)
+                        context.fill(CGRect(origin: CGPoint(), size: size))
+                    })?.stretchableImage(withLeftCapWidth: Int(cornerRadius) + 5, topCapHeight: Int(cornerRadius) + 5).withRenderingMode(.alwaysTemplate)
+                }
+            } else {
+                if component.smoothCorners {
+                    let size = CGSize(width: cornerRadius * 2.0 + 10.0, height: cornerRadius * 2.0 + 10.0)
+                    if let cornerImage = self.cornerImage, cornerImage.size == size {
+                    } else {
+                        self.cornerImage = generateImage(size, rotatedContext: { size, context in
+                            context.clear(CGRect(origin: CGPoint(), size: size))
+                            context.addPath(UIBezierPath(roundedRect: CGRect(origin: CGPoint(), size: size), cornerRadius: cornerRadius).cgPath)
+                            context.setFillColor(UIColor.white.cgColor)
+                            context.fillPath()
+                        })?.stretchableImage(withLeftCapWidth: Int(cornerRadius) + 5, topCapHeight: Int(cornerRadius) + 5).withRenderingMode(.alwaysTemplate)
+                    }
+                } else {
+                    let size = CGSize(width: cornerRadius * 2.0, height: cornerRadius * 2.0)
+                    if let cornerImage = self.cornerImage, cornerImage.size == size {
+                    } else {
+                        self.cornerImage = generateStretchableFilledCircleImage(diameter: size.width, color: UIColor.white)?.withRenderingMode(.alwaysTemplate)
+                    }
+                }
+            }
+            self.image = self.cornerImage
+            self.clipsToBounds = false
+            self.backgroundColor = nil
+            self.layer.cornerRadius = 0.0
+        }
+        
+        func update(component: FilledRoundedRectangleComponent, availableSize: CGSize, transition: ComponentTransition) -> CGSize {
+            self.component = component
+            
+            transition.setTintColor(view: self, color: component.color)
+            
+            let cornerRadius: CGFloat
+            switch component.cornerRadius {
+            case let .value(value):
+                cornerRadius = value
+            case .minEdge:
+                cornerRadius = min(availableSize.width, availableSize.height) * 0.5
+            }
+            
+            if self.currentCornerRadius != cornerRadius {
+                let previousCornerRadius = self.currentCornerRadius
+                self.currentCornerRadius = cornerRadius
+                if transition.animation.isImmediate {
+                    self.applyStaticCornerRadius()
+                } else {
+                    self.image = nil
+                    self.clipsToBounds = true
+                    self.backgroundColor = component.color
+                    if let previousCornerRadius, self.layer.animation(forKey: "cornerRadius") == nil {
+                        self.layer.cornerRadius = previousCornerRadius
+                    }
+                    if #available(iOS 13.0, *) {
+                        if component.smoothCorners {
+                            self.layer.cornerCurve = .continuous
+                        } else {
+                            self.layer.cornerCurve = .circular
+                        }
+                        
+                    }
+                    transition.setCornerRadius(layer: self.layer, cornerRadius: cornerRadius, completion: { [weak self] completed in
+                        guard let self, completed else {
+                            return
+                        }
+                        self.applyStaticCornerRadius()
+                    })
+                }
+            }
+            
+            return availableSize
+        }
+    }
+    
+    public func makeView() -> View {
+        return View(frame: CGRect())
+    }
+    
+    public func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+        return view.update(component: self, availableSize: availableSize, transition: transition)
+    }
+}
+
+open class SolidRoundedCornersContainer: UIView {
+    public final class Params: Equatable {
+        public let size: CGSize
+        public let color: UIColor
+        public let cornerRadius: CGFloat
+        public let smoothCorners: Bool
+        
+        public init(
+            size: CGSize,
+            color: UIColor,
+            cornerRadius: CGFloat,
+            smoothCorners: Bool
+        ) {
+            self.size = size
+            self.color = color
+            self.cornerRadius = cornerRadius
+            self.smoothCorners = smoothCorners
+        }
+        
+        public static func ==(lhs: Params, rhs: Params) -> Bool {
+            if lhs === rhs {
+                return true
+            }
+            if lhs.size != rhs.size {
+                return false
+            }
+            if lhs.color != rhs.color {
+                return false
+            }
+            if lhs.cornerRadius != rhs.cornerRadius {
+                return false
+            }
+            if lhs.smoothCorners != rhs.smoothCorners {
+                return false
+            }
+            return true
+        }
+    }
+    
+    public let cornersView: UIImageView
+    
+    private var params: Params?
+    private var currentCornerRadius: CGFloat?
+    private var cornerImage: UIImage?
+    
+    override public init(frame: CGRect) {
+        self.cornersView = UIImageView()
+        
+        super.init(frame: frame)
+        
+        self.clipsToBounds = true
+        
+        self.addSubview(self.cornersView)
+    }
+    
+    required public init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    private func applyStaticCornerRadius() {
+        guard let params = self.params else {
+            return
+        }
+        guard let cornerRadius = self.currentCornerRadius else {
+            return
+        }
+        if cornerRadius == 0.0 {
+            if let cornerImage = self.cornerImage, cornerImage.size.width == 1.0 {
+            } else {
+                self.cornerImage = generateImage(CGSize(width: 1.0, height: 1.0), rotatedContext: { size, context in
+                    context.setFillColor(UIColor.clear.cgColor)
+                    context.fill(CGRect(origin: CGPoint(), size: size))
+                })?.stretchableImage(withLeftCapWidth: Int(cornerRadius) + 5, topCapHeight: Int(cornerRadius) + 5).withRenderingMode(.alwaysTemplate)
+            }
+        } else {
+            if params.smoothCorners {
+                let size = CGSize(width: cornerRadius * 2.0 + 10.0, height: cornerRadius * 2.0 + 10.0)
+                if let cornerImage = self.cornerImage, cornerImage.size == size {
+                } else {
+                    self.cornerImage = generateImage(size, rotatedContext: { size, context in
+                        context.setFillColor(UIColor.white.cgColor)
+                        context.fill(CGRect(origin: CGPoint(), size: size))
+                        context.addPath(UIBezierPath(roundedRect: CGRect(origin: CGPoint(), size: size), cornerRadius: cornerRadius).cgPath)
+                        context.setFillColor(UIColor.clear.cgColor)
+                        context.setBlendMode(.copy)
+                        context.fillPath()
+                    })?.stretchableImage(withLeftCapWidth: Int(cornerRadius) + 5, topCapHeight: Int(cornerRadius) + 5).withRenderingMode(.alwaysTemplate)
+                }
+            } else {
+                let size = CGSize(width: cornerRadius * 2.0, height: cornerRadius * 2.0)
+                if let cornerImage = self.cornerImage, cornerImage.size == size {
+                } else {
+                    self.cornerImage = generateStretchableFilledCircleImage(diameter: size.width, color: nil, backgroundColor: .white)?.withRenderingMode(.alwaysTemplate)
+                }
+            }
+        }
+        self.cornersView.image = self.cornerImage
+        self.backgroundColor = nil
+        self.layer.cornerRadius = 0.0
+    }
+        
+    public func update(params: Params, transition: ComponentTransition) {
+        if self.params == params {
+            return
+        }
+        self.params = params
+        
+        transition.setTintColor(view: self.cornersView, color: params.color)
+        
+        if self.currentCornerRadius != params.cornerRadius {
+            let previousCornerRadius = self.currentCornerRadius
+            self.currentCornerRadius = params.cornerRadius
+            if transition.animation.isImmediate {
+                self.applyStaticCornerRadius()
+            } else {
+                self.cornersView.image = nil
+                self.clipsToBounds = true
+                if let previousCornerRadius, self.layer.animation(forKey: "cornerRadius") == nil {
+                    self.layer.cornerRadius = previousCornerRadius
+                }
+                if #available(iOS 13.0, *) {
+                    if params.smoothCorners {
+                        self.layer.cornerCurve = .continuous
+                    } else {
+                        self.layer.cornerCurve = .circular
+                    }
+                    
+                }
+                transition.setCornerRadius(layer: self.layer, cornerRadius: params.cornerRadius, completion: { [weak self] completed in
+                    guard let self, completed else {
+                        return
+                    }
+                    self.applyStaticCornerRadius()
+                })
+            }
+        }
+    }
+}

submodules/ComponentFlow/Source/Components/Text.swift

@@ -0,0 +1,110 @@
+import Foundation
+import UIKit
+
+public final class Text: Component {
+    private final class MeasureState: Equatable {
+        let attributedText: NSAttributedString
+        let availableSize: CGSize
+        let size: CGSize
+        
+        init(attributedText: NSAttributedString, availableSize: CGSize, size: CGSize) {
+            self.attributedText = attributedText
+            self.availableSize = availableSize
+            self.size = size
+        }
+
+        static func ==(lhs: MeasureState, rhs: MeasureState) -> Bool {
+            if !lhs.attributedText.isEqual(rhs.attributedText) {
+                return false
+            }
+            if lhs.availableSize != rhs.availableSize {
+                return false
+            }
+            if lhs.size != rhs.size {
+                return false
+            }
+            return true
+        }
+    }
+    
+    public final class View: UIView {
+        private var measureState: MeasureState?
+
+        public func update(component: Text, availableSize: CGSize, transition: ComponentTransition) -> CGSize {
+            let attributedText = NSAttributedString(string: component.text, attributes: [
+                NSAttributedString.Key.font: component.font,
+                NSAttributedString.Key.foregroundColor: component.color
+            ])
+            
+            if let tintColor = component.tintColor {
+                transition.setTintColor(layer: self.layer, color: tintColor)
+            }
+            
+            if let measureState = self.measureState {
+                if measureState.attributedText.isEqual(to: attributedText) && measureState.availableSize == availableSize {
+                    return measureState.size
+                }
+            }
+            
+            var boundingRect = attributedText.boundingRect(with: availableSize, options: .usesLineFragmentOrigin, context: nil)
+            boundingRect.size.width = ceil(boundingRect.size.width)
+            boundingRect.size.height = ceil(boundingRect.size.height)
+
+            let measureState = MeasureState(attributedText: attributedText, availableSize: availableSize, size: boundingRect.size)
+            if #available(iOS 10.0, *) {
+                let renderer = UIGraphicsImageRenderer(bounds: CGRect(origin: CGPoint(), size: measureState.size))
+                let image = renderer.image { context in
+                    UIGraphicsPushContext(context.cgContext)
+                    measureState.attributedText.draw(at: CGPoint())
+                    UIGraphicsPopContext()
+                }
+                self.layer.contents = image.cgImage
+            } else {
+                UIGraphicsBeginImageContextWithOptions(measureState.size, false, 0.0)
+                measureState.attributedText.draw(at: CGPoint())
+                self.layer.contents = UIGraphicsGetImageFromCurrentImageContext()?.cgImage
+                UIGraphicsEndImageContext()
+            }
+
+            self.measureState = measureState
+            
+            return boundingRect.size
+        }
+    }
+    
+    public let text: String
+    public let font: UIFont
+    public let color: UIColor
+    public let tintColor: UIColor?
+    
+    public init(text: String, font: UIFont, color: UIColor, tintColor: UIColor? = nil) {
+        self.text = text
+        self.font = font
+        self.color = color
+        self.tintColor = tintColor
+    }
+
+    public static func ==(lhs: Text, rhs: Text) -> Bool {
+        if lhs.text != rhs.text {
+            return false
+        }
+        if !lhs.font.isEqual(rhs.font) {
+            return false
+        }
+        if !lhs.color.isEqual(rhs.color) {
+            return false
+        }
+        if lhs.tintColor != rhs.tintColor {
+            return false
+        }
+        return true
+    }
+    
+    public func makeView() -> View {
+        return View()
+    }
+    
+    public func update(view: View, availableSize: CGSize, state: EmptyComponentState, environment: Environment<Empty>, transition: ComponentTransition) -> CGSize {
+        return view.update(component: self, availableSize: availableSize, transition: transition)
+    }
+}

submodules/ComponentFlow/Source/Components/TransformContents.swift

@@ -0,0 +1,54 @@
+import Foundation
+import UIKit
+
+public final class TransformContents<ChildEnvironment: Equatable>: CombinedComponent {
+    public typealias EnvironmentType = ChildEnvironment
+
+    private let content: AnyComponent<ChildEnvironment>
+    private let fixedSize: CGSize?
+    private let translation: CGPoint
+
+    public init(content: AnyComponent<ChildEnvironment>, fixedSize: CGSize? = nil, translation: CGPoint) {
+        self.content = content
+        self.fixedSize = fixedSize
+        self.translation = translation
+    }
+
+    public static func ==(lhs: TransformContents<ChildEnvironment>, rhs: TransformContents<ChildEnvironment>) -> Bool {
+        if lhs.content != rhs.content {
+            return false
+        }
+        if lhs.fixedSize != rhs.fixedSize {
+            return false
+        }
+        if lhs.translation != rhs.translation {
+            return false
+        }
+        return true
+    }
+
+    public static var body: Body {
+        let child = Child(environment: ChildEnvironment.self)
+
+        return { context in
+            let child = child.update(
+                component: context.component.content,
+                environment: { context.environment[ChildEnvironment.self] },
+                availableSize: context.availableSize,
+                transition: context.transition
+            )
+
+            let size = context.component.fixedSize ?? child.size
+
+            var childFrame = child.size.centered(in: CGRect(origin: CGPoint(), size: size))
+            childFrame.origin.x += context.component.translation.x
+            childFrame.origin.y += context.component.translation.y
+
+            context.add(child
+                .position(childFrame.center)
+            )
+
+            return size
+        }
+    }
+}

submodules/ComponentFlow/Source/Components/VStack.swift

@@ -0,0 +1,88 @@
+import Foundation
+import UIKit
+
+public enum VStackAlignment {
+    case left
+    case center
+    case right
+}
+
+public final class VStack<ChildEnvironment: Equatable>: CombinedComponent {
+    public typealias EnvironmentType = ChildEnvironment
+
+    private let items: [AnyComponentWithIdentity<ChildEnvironment>]
+    private let alignment: VStackAlignment
+    private let spacing: CGFloat
+    private let fillWidth: Bool
+
+    public init(_ items: [AnyComponentWithIdentity<ChildEnvironment>], alignment: VStackAlignment = .center, spacing: CGFloat, fillWidth: Bool = false) {
+        self.items = items
+        self.alignment = alignment
+        self.spacing = spacing
+        self.fillWidth = fillWidth
+    }
+
+    public static func ==(lhs: VStack<ChildEnvironment>, rhs: VStack<ChildEnvironment>) -> Bool {
+        if lhs.items != rhs.items {
+            return false
+        }
+        if lhs.alignment != rhs.alignment {
+            return false
+        }
+        if lhs.spacing != rhs.spacing {
+            return false
+        }
+        if lhs.fillWidth != rhs.fillWidth {
+            return false
+        }
+        return true
+    }
+
+    public static var body: Body {
+        let children = ChildMap(environment: ChildEnvironment.self, keyedBy: AnyHashable.self)
+
+        return { context in
+            let updatedChildren = context.component.items.map { item in
+                return children[item.id].update(
+                    component: item.component, environment: {
+                        context.environment[ChildEnvironment.self]
+                    },
+                    availableSize: context.availableSize,
+                    transition: context.transition
+                )
+            }
+
+            var size = CGSize(width: 0.0, height: 0.0)
+            if context.component.fillWidth {
+                size.width = context.availableSize.width
+            }
+            for child in updatedChildren {
+                size.height += child.size.height
+                size.width = max(size.width, child.size.width)
+            }
+            size.height += context.component.spacing * CGFloat(updatedChildren.count - 1)
+            
+            var nextY = 0.0
+            for child in updatedChildren {
+                let childFrame: CGRect
+                switch context.component.alignment {
+                case .left:
+                    childFrame = CGRect(origin: CGPoint(x: 0.0, y: nextY), size: child.size)
+                case .center:
+                    childFrame = CGRect(origin: CGPoint(x: floor((size.width - child.size.width) * 0.5), y: nextY), size: child.size)
+                case .right:
+                    childFrame = CGRect(origin: CGPoint(x: size.width - child.size.width, y: nextY), size: child.size)
+                }
+                context.add(child
+                    .position(childFrame.center)
+                    .appear(.default(scale: true, alpha: true))
+                    .disappear(.default(scale: true, alpha: true))
+                )
+                nextY += child.size.height
+                nextY += context.component.spacing
+            }
+
+            return size
+        }
+    }
+}

submodules/ComponentFlow/Source/Components/ZStack.swift

@@ -0,0 +1,49 @@
+import Foundation
+import UIKit
+
+public final class ZStack<ChildEnvironment: Equatable>: CombinedComponent {
+    public typealias EnvironmentType = ChildEnvironment
+
+    private let items: [AnyComponentWithIdentity<ChildEnvironment>]
+
+    public init(_ items: [AnyComponentWithIdentity<ChildEnvironment>]) {
+        self.items = items
+    }
+
+    public static func ==(lhs: ZStack<ChildEnvironment>, rhs: ZStack<ChildEnvironment>) -> Bool {
+        if lhs.items != rhs.items {
+            return false
+        }
+        return true
+    }
+
+    public static var body: Body {
+        let children = ChildMap(environment: ChildEnvironment.self, keyedBy: AnyHashable.self)
+
+        return { context in
+            let updatedChildren = context.component.items.map { item in
+                return children[item.id].update(
+                    component: item.component, environment: {
+                        context.environment[ChildEnvironment.self]
+                    },
+                    availableSize: context.availableSize,
+                    transition: context.transition
+                )
+            }
+
+            var size = CGSize(width: 0.0, height: 0.0)
+            for child in updatedChildren {
+                size.width = max(size.width, child.size.width)
+                size.height = max(size.height, child.size.height)
+            }
+
+            for child in updatedChildren {
+                context.add(child
+                    .position(child.size.centered(in: CGRect(origin: CGPoint(), size: size)).center)
+                )
+            }
+
+            return size
+        }
+    }
+}