Add Anchor API implementation

Sources/OpenSwiftUICore/Layout/Geometry/Anchor+Point.swift

@@ -0,0 +1,88 @@
+//
+//  Anchor+Point.swift
+//  OpenSwiftUICore
+//
+//  Audited for 6.5.4
+//  Status: Complete
+
+public import OpenCoreGraphicsShims
+
+extension CGPoint: AnchorProtocol {
+    package static var defaultAnchor: CGPoint {
+        .zero
+    }
+
+    package func prepare(geometry: AnchorGeometry) -> CGPoint {
+        var point = self
+        point.convert(to: .global, transform: geometry.transform)
+        return point
+    }
+
+    package static func hashValue(_ value: CGPoint, into hasher: inout Hasher) {
+        hasher.combine(value.x)
+        hasher.combine(value.y)
+    }
+}
+
+extension UnitPoint: AnchorProtocol {
+    package static var defaultAnchor: CGPoint {
+        .zero
+    }
+
+    package func prepare(geometry: AnchorGeometry) -> CGPoint {
+        let point = `in`(geometry.size)
+        return point.prepare(geometry: geometry)
+    }
+
+    package static func hashValue(_ value: CGPoint, into hasher: inout Hasher) {
+        hasher.combine(value.x)
+        hasher.combine(value.y)
+    }
+}
+
+@available(OpenSwiftUI_v1_0, *)
+extension Anchor.Source where Value == CGPoint {
+    public static func point(_ p: CGPoint) -> Anchor<Value>.Source {
+        .init(anchor: p)
+    }
+
+    public static func unitPoint(_ p: UnitPoint) -> Anchor<Value>.Source {
+        .init(anchor: p)
+    }
+
+    public static var topLeading: Anchor<CGPoint>.Source {
+        unitPoint(.topLeading)
+    }
+
+    public static var top: Anchor<CGPoint>.Source {
+        unitPoint(.top)
+    }
+
+    public static var topTrailing: Anchor<CGPoint>.Source {
+        unitPoint(.topTrailing)
+    }
+
+    public static var leading: Anchor<CGPoint>.Source {
+        unitPoint(.leading)
+    }
+
+    public static var center: Anchor<CGPoint>.Source {
+        unitPoint(.center)
+    }
+
+    public static var trailing: Anchor<CGPoint>.Source {
+        unitPoint(.trailing)
+    }
+
+    public static var bottomLeading: Anchor<CGPoint>.Source {
+        unitPoint(.bottomLeading)
+    }
+
+    public static var bottom: Anchor<CGPoint>.Source {
+        unitPoint(.bottom)
+    }
+
+    public static var bottomTrailing: Anchor<CGPoint>.Source {
+        unitPoint(.bottomTrailing)
+    }
+}