Merge pull request #14 from spacenation/rounded-regular-polygons

Rounded polygons

Author: ay42

Package.swift

@@ -12,6 +12,7 @@ let package = Package(
         .library(name: "Shapes", targets: ["Shapes"])
     ],
     targets: [
-        .target(name: "Shapes", dependencies: [])
+        .target(name: "Shapes", dependencies: []),
+        .testTarget(name: "ShapesTests", dependencies: ["Shapes"])
     ]
 )

Sources/Shapes/CGPoint+Extensions.swift

@@ -28,6 +28,24 @@ public extension CGPoint {
     }
 }
 
+public extension CGPoint {
+    static func intersection(start1: CGPoint, end1: CGPoint, start2: CGPoint, end2: CGPoint) -> CGPoint {
+        let x1 = start1.x
+        let y1 = start1.y
+        let x2 = end1.x
+        let y2 = end1.y
+        let x3 = start2.x
+        let y3 = start2.y
+        let x4 = end2.x
+        let y4 = end2.y
+        
+        let intersectionX: CGFloat = ((x1*y2-y1*x2)*(x3-x4) - (x1-x2)*(x3*y4-y3*x4)) / ((x1-x2)*(y3-y4) - (y1-y2)*(x3-x4))
+        let intersectionY: CGFloat = ((x1*y2-y1*x2)*(y3-y4) - (y1-y2)*(x3*y4-y3*x4)) / ((x1-x2)*(y3-y4) - (y1-y2)*(x3-x4))
+        
+        return CGPoint(x: intersectionX, y: intersectionY)
+    }
+}
+
 public extension Collection where Element == UnitPoint {
     func points(in rect: CGRect) -> [CGPoint] {
         self.map { CGPoint(unitPoint: $0, in: rect) }

Sources/Shapes/Lines/QuadCurve.swift

@@ -2,7 +2,7 @@ import SwiftUI
 
 public struct QuadCurve: Shape {
     let unitPoints: [UnitPoint]
-
+    
     public func path(in rect: CGRect) -> Path {
         Path { path in
             path.addQuadCurves(self.unitPoints.points(in: rect))

Sources/Shapes/Path+Extensions.swift

@@ -0,0 +1,31 @@
+import SwiftUI
+
+public extension Path {
+    mutating func addCircularCornerRadiusArc(from point: CGPoint, via viaPoint: CGPoint, to nextPoint: CGPoint, radius: CGFloat, clockwise: Bool) {
+        let lineAngle = atan2(viaPoint.y - point.y, viaPoint.x - point.x)
+        let nextLineAngle = atan2(nextPoint.y - viaPoint.y, nextPoint.x - viaPoint.x)
+        
+        let lineVector = CGVector(dx: -sin(lineAngle) * radius, dy: cos(lineAngle) * radius)
+        let nextLineVector = CGVector(dx: -sin(nextLineAngle) * radius, dy: cos(nextLineAngle) * radius)
+        
+        let offsetStart1 = CGPoint(x: point.x + lineVector.dx, y: point.y + lineVector.dy)
+        let offsetEnd1 = CGPoint(x: viaPoint.x + lineVector.dx, y: viaPoint.y + lineVector.dy)
+        
+        let offsetStart2 = CGPoint(x: viaPoint.x + nextLineVector.dx, y: viaPoint.y + nextLineVector.dy)
+        
+        let offsetEnd2 = CGPoint(x: nextPoint.x + nextLineVector.dx, y: nextPoint.y + nextLineVector.dy)
+        
+        let intersection = CGPoint.intersection(start1: offsetStart1, end1: offsetEnd1, start2: offsetStart2, end2: offsetEnd2)
+        
+        let startAngle = lineAngle - (.pi / 2)
+        let endAngle = nextLineAngle - (.pi / 2)
+        
+        self.addArc(
+            center: intersection,
+            radius: radius,
+            startAngle: Angle(radians: startAngle),
+            endAngle: Angle(radians:endAngle),
+            clockwise: clockwise
+        )
+    }
+}

Sources/Shapes/RegularPolygons/Triangle.swift

@@ -0,0 +1,62 @@
+import SwiftUI
+
+struct Triangle: Shape {
+    let radius: CGFloat
+    
+    func path(in rect: CGRect) -> Path {
+        let width = rect.width
+        let height = rect.height
+        let sides = 3
+        let hypotenuse = Double(min(width, height)) / 2.0
+        let centerPoint = CGPoint(x: rect.midX, y: rect.midY)
+        var usableRadius: CGFloat = .zero
+        
+        return Path { path in
+            guard sides > 2 else { return }
+            (0..<sides).forEach { index in
+                
+                let angle = ((Double(index) * (360.0 / Double(sides))) - 90) * Double.pi / 180
+
+                let point = CGPoint(
+                    x: centerPoint.x + CGFloat(cos(angle) * hypotenuse),
+                    y: centerPoint.y + CGFloat(sin(angle) * hypotenuse)
+                )
+                
+                let viaAngle = ((Double(index + 1) * (360.0 / Double(sides))) - 90) * Double.pi / 180
+
+                let viaPoint = CGPoint(
+                    x: centerPoint.x + CGFloat(cos(viaAngle) * hypotenuse),
+                    y: centerPoint.y + CGFloat(sin(viaAngle) * hypotenuse)
+                )
+                
+                if usableRadius == 0 {
+                    let sideLength = sqrt((point.x - viaPoint.x) * (point.x - viaPoint.x) + (point.y - viaPoint.y) * (point.y - viaPoint.y))
+                    let inradius = sideLength / (2 * tan(.pi / CGFloat(sides)))
+                    
+                    usableRadius = min(radius, inradius)
+                }
+                
+                let nextAngle = ((Double(index + 2) * (360.0 / Double(sides))) - 90) * Double.pi / 180
+                
+                let nextPoint = CGPoint(
+                    x: centerPoint.x + CGFloat(cos(nextAngle) * hypotenuse),
+                    y: centerPoint.y + CGFloat(sin(nextAngle) * hypotenuse)
+                )
+                
+                path.addCircularCornerRadiusArc(from: point, via: viaPoint, to: nextPoint, radius: usableRadius, clockwise: false)
+            }
+            path.closeSubpath()
+        }
+    }
+}
+
+struct Triangle_Previews: PreviewProvider {
+    static var previews: some View {
+        Triangle(radius: 30)
+            .stroke(lineWidth: 3)
+            .foregroundColor(.blue)
+            .background(Circle())
+            .animation(.linear)
+            .previewLayout(.fixed(width: 200, height: 200))
+    }
+}

Sources/Shapes/RoundedRegularPolygons/RoundedRegularPolygon.swift

@@ -26,20 +26,69 @@ extension RoundedRegularPolygon: InsettableShape {
     }
 }
 
+extension Path {
+    static func roundedRegularPolygon(sides: UInt, in rect: CGRect, inset: CGFloat = 0, radius: CGFloat = 0) -> Path {
+        let rect = rect.insetBy(dx: inset, dy: inset)
+        let width = rect.width
+        let height = rect.height
+        let hypotenuse = Double(min(width, height)) / 2.0
+        let centerPoint = CGPoint(x: rect.midX, y: rect.midY)
+        var usableRadius: CGFloat = .zero
+        
+        return Path { path in
+            guard sides > 2 else { return }
+            (0..<sides).forEach { index in
+                
+                let angle = ((Double(index) * (360.0 / Double(sides))) - 90) * Double.pi / 180
+                
+                let point = CGPoint(
+                    x: centerPoint.x + CGFloat(cos(angle) * hypotenuse),
+                    y: centerPoint.y + CGFloat(sin(angle) * hypotenuse)
+                )
+                
+                let viaAngle = ((Double(index + 1) * (360.0 / Double(sides))) - 90) * Double.pi / 180
+                
+                let viaPoint = CGPoint(
+                    x: centerPoint.x + CGFloat(cos(viaAngle) * hypotenuse),
+                    y: centerPoint.y + CGFloat(sin(viaAngle) * hypotenuse)
+                )
+                
+                if usableRadius == 0 {
+                    let sideLength = sqrt((point.x - viaPoint.x) * (point.x - viaPoint.x) + (point.y - viaPoint.y) * (point.y - viaPoint.y))
+                    let inradius = sideLength / (2 * tan(.pi / CGFloat(sides)))
+                    
+                    usableRadius = min(radius, inradius)
+                }
+                
+                let nextAngle = ((Double(index + 2) * (360.0 / Double(sides))) - 90) * Double.pi / 180
+                
+                let nextPoint = CGPoint(
+                    x: centerPoint.x + CGFloat(cos(nextAngle) * hypotenuse),
+                    y: centerPoint.y + CGFloat(sin(nextAngle) * hypotenuse)
+                )
+                
+                path.addCircularCornerRadiusArc(from: point, via: viaPoint, to: nextPoint, radius: usableRadius, clockwise: false)
+            }
+            path.closeSubpath()
+        }
+    }
+}
+
+
 struct RoundedRegularPolygon_Previews: PreviewProvider {
     static var previews: some View {
-        Group {
-            RoundedRegularPolygon(sides: 4, radius: 40)
-                .strokeBorder(lineWidth: 20)
-                .foregroundColor(.blue)
-            
-            RoundedRegularPolygon(sides: 6, radius: 20)
-                .strokeBorder(lineWidth: 10)
-                .foregroundColor(.yellow)
-            
-            RoundedRegularPolygon(sides: 16, radius: 10)
-                .strokeBorder(lineWidth: 20)
-                .foregroundColor(.green)
-        }
+        RoundedRegularPolygon(sides: 3, radius: 30)
+            .fill(LinearGradient(gradient: Gradient(colors: [.orange, .red]), startPoint: .topLeading, endPoint: .bottomTrailing))
+            .previewLayout(.fixed(width: 200, height: 200))
+        
+        RoundedRegularPolygon(sides: 6, radius: 20)
+            .strokeBorder(lineWidth: 20)
+            .foregroundColor(.yellow)
+            .previewLayout(.fixed(width: 200, height: 200))
+        
+        RoundedRegularPolygon(sides: 16, radius: 10)
+            .strokeBorder(lineWidth: 20)
+            .foregroundColor(.green)
+            .previewLayout(.fixed(width: 200, height: 200))
     }
 }