Stream improvements

submodules/ComponentFlow/Source/Components/Circle.swift

@@ -0,0 +1,60 @@
+import Foundation
+import UIKit
+
+public final class Circle: Component {
+    public let color: UIColor
+    public let size: CGSize
+    public let width: CGFloat
+    
+    public init(color: UIColor, size: CGSize, width: CGFloat) {
+        self.color = color
+        self.size = size
+        self.width = width
+    }
+
+    public static func ==(lhs: Circle, rhs: Circle) -> Bool {
+        if !lhs.color.isEqual(rhs.color) {
+            return false
+        }
+        if lhs.size != rhs.size {
+            return false
+        }
+        if lhs.width != rhs.width {
+            return false
+        }
+        return true
+    }
+    
+    public final class View: UIImageView {
+        var component: Circle?
+        var currentSize: CGSize?
+        
+        func update(component: Circle, availableSize: CGSize, transition: Transition) -> 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.setStrokeColor(component.color.cgColor)
+                    context.setLineWidth(component.width)
+                    context.strokeEllipse(in: CGRect(origin: CGPoint(), size: size).insetBy(dx: component.width / 2.0, dy: component.width / 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: Transition) -> CGSize {
+        return view.update(component: self, availableSize: availableSize, transition: transition)
+    }
+}