Implement Path in WinUIBackend

Author: bbrk24

Examples/Package.resolved

@@ -65,5 +65,9 @@ let package = Package(
             name: "NotesExample",
             dependencies: exampleDependencies
         ),
+        .executableTarget(
+            name: "PathsExample",
+            dependencies: exampleDependencies
+        )
     ]
 )

Examples/Package.swift

@@ -0,0 +1,96 @@
+import SwiftCrossUI
+import DefaultBackend
+import Foundation // for sin, cos
+
+struct ArcShape: StyledShape {
+    var startAngle: Double
+    var endAngle: Double
+    var clockwise: Bool
+
+    var strokeColor: Color? = Color.green
+    let fillColor: Color? = nil
+    let strokeStyle: StrokeStyle? = StrokeStyle(width: 5.0)
+
+    func path(in bounds: Path.Rect) -> Path {
+        let radius = min(bounds.width, bounds.height) / 2.0 - 2.5
+        
+        return Path()
+            .move(to: bounds.center + radius * SIMD2(x: cos(startAngle), y: sin(startAngle)))
+            .addArc(
+                center: bounds.center,
+                radius: radius,
+                startAngle: startAngle,
+                endAngle: endAngle,
+                clockwise: clockwise
+            )
+    }
+
+    func size(fitting proposal: SIMD2<Int>) -> ViewSize {
+        let diameter = max(11, min(proposal.x, proposal.y))
+        return ViewSize(
+            size: SIMD2(x: diameter, y: diameter),
+            idealSize: SIMD2(x: 100, y: 100),
+            idealWidthForProposedHeight: proposal.y,
+            idealHeightForProposedWidth: proposal.x,
+            minimumWidth: 11,
+            minimumHeight: 11,
+            maximumWidth: nil,
+            maximumHeight: nil
+        )
+    }
+}
+
+struct PathsApp: App {
+    var body: some Scene {
+        WindowGroup("PathsApp") {
+            HStack {
+                ZStack {
+                    RoundedRectangle(cornerRadius: 12)
+                        .fill(.gray)
+
+                    HStack {
+                        VStack {
+                            Text("Clockwise")
+
+                            HStack {
+                                ArcShape(startAngle: .pi * 2.0/3.0, endAngle: .pi * 1.5, clockwise: true)
+
+                                ArcShape(startAngle: .pi * 1.5, endAngle: .pi * 1.0/3.0, clockwise: true)
+                            }
+
+                            HStack {                            
+                                ArcShape(startAngle: .pi * 1.5, endAngle: .pi * 2.0/3.0, clockwise: true)
+
+                                ArcShape(startAngle: .pi * 1.0/3.0, endAngle: .pi * 1.5, clockwise: true)
+                            }
+                        }
+                        
+                        VStack {
+                            Text("Counter-clockwise")
+
+                            HStack {                            
+                                ArcShape(startAngle: .pi * 1.5, endAngle: .pi * 2.0/3.0, clockwise: false)
+
+                                ArcShape(startAngle: .pi * 1.0/3.0, endAngle: .pi * 1.5, clockwise: false)
+                            }
+
+                            HStack {
+                                ArcShape(startAngle: .pi * 2.0/3.0, endAngle: .pi * 1.5, clockwise: false)
+
+                                ArcShape(startAngle: .pi * 1.5, endAngle: .pi * 1.0/3.0, clockwise: false)
+                            }
+                        }
+                    }.padding()
+                }
+                .padding()
+
+                Ellipse()
+                    .fill(.blue)
+                    .padding()
+            }
+        }
+    }
+}
+
+// Even though this file isn't called main.swift, `@main` isn't allowed and this is
+PathsApp.main()

Examples/Sources/PathsExample/PathsApp.swift

@@ -107,7 +107,7 @@ let package = Package(
         ),
         .package(
             url: "https://github.com/stackotter/swift-winui",
-            branch: "42fe0034b7162f2de71ceea95725915d1147455a"
+            branch: "a81bc36e3ac056fbc740e9df30ff0d80af5ecd21"
         ),
         // .package(
         //     url: "https://github.com/stackotter/TermKit",

Package.resolved

@@ -266,13 +266,32 @@ public struct Path {
         return self
     }
 
+    /// Add an arc segment to the path.
+    /// 
+    /// The behavior is not defined if the starting point is not what is implied by `center`,
+    /// `radius`, and `startAngle`. Some backends (such as UIKit) will add a line segment
+    /// to connect the arc to the starting point, while others (such as WinUI) will move the
+    /// arc in unintuitive ways. If this arc is the first segment of the current path, or
+    /// the previous segment was a rectangle or circle, be sure to call ``move(to:)`` before
+    /// this.
+    /// - Parameters:
+    ///   - center: The location of the center of the circle.
+    ///   - radius: The radius of the circle.
+    ///   - startAngle: The angle of the start of the arc, measured in radians clockwise from
+    //      right. Must be between 0 and 2pi (inclusive).
+    ///   - endAngle: The angle of the end of the arc, measured in radians clockwise from right.
+    ///     Must be between 0 and 2pi (inclusive).
+    ///   - clockwise: `true` if the arc is to be drawn clockwise, `false` if the arc is to
+    ///     be drawn counter-clockwise. Used to determine whether to draw the larger arc or
+    ///     the smaller arc identified by the given start and end angles.
     public consuming func addArc(
         center: SIMD2<Double>,
         radius: Double,
         startAngle: Double,
         endAngle: Double,
         clockwise: Bool
     ) -> Path {
+        assert((0.0 ... (2.0 * .pi)).contains(startAngle) && (0.0 ... (2.0 * .pi)).contains(endAngle))
         actions.append(
             .arc(
                 center: center,