SwiftUI 绘制圆角三角

圆角三角形.swift

struct RoundedEquilateralTriangle: Shape {
    var sideLength: CGFloat
    var leftRadius: CGFloat
    var topRadius: CGFloat
    var rightRadius: CGFloat

    func path(in rect: CGRect) -> Path {
        var path = Path()

        let height = sideLength * sqrt(3) / 2  // 等边三角形的高

        // 计算三角形的中心点
        let center = CGPoint(x: rect.width / 2, y: rect.height / 2)

        // 计算三个顶点坐标（相对于中心点）
        let topPoint = CGPoint(x: center.x, y: center.y - 2 * height / 3)
        let bottomLeftPoint = CGPoint(x: center.x - sideLength / 2, y: center.y + height / 3)
        let bottomRightPoint = CGPoint(x: center.x + sideLength / 2, y: center.y + height / 3)

        // 计算每个圆角的起始和结束点
        let topCornerStart = pointAlongLine(from: bottomLeftPoint, to: topPoint, distance: leftRadius)
        let topCornerEnd = pointAlongLine(from: bottomRightPoint, to: topPoint, distance: topRadius)

        let leftCornerStart = pointAlongLine(from: topPoint, to: bottomLeftPoint, distance: leftRadius)
        let leftCornerEnd = pointAlongLine(from: bottomRightPoint, to: bottomLeftPoint, distance: rightRadius)

        let rightCornerStart = pointAlongLine(from: bottomLeftPoint, to: bottomRightPoint, distance: rightRadius)
        let rightCornerEnd = pointAlongLine(from: topPoint, to: bottomRightPoint, distance: topRadius)

        // 绘制路径
        path.move(to: topCornerStart)
        path.addLine(to: leftCornerStart)
        path.addArc(tangent1End: bottomLeftPoint, tangent2End: leftCornerEnd, radius: leftRadius)
        path.addLine(to: rightCornerStart)
        path.addArc(tangent1End: bottomRightPoint, tangent2End: rightCornerEnd, radius: rightRadius)
        path.addLine(to: topCornerEnd)
        path.addArc(tangent1End: topPoint, tangent2End: topCornerStart, radius: topRadius)
        path.closeSubpath()

        return path
    }

    // 计算从一点沿线段方向前进指定距离的点
    private func pointAlongLine(from: CGPoint, to: CGPoint, distance: CGFloat) -> CGPoint {
        let totalDistance = sqrt(pow(to.x - from.x, 2) + pow(to.y - from.y, 2))
        let ratio = distance / totalDistance

        let x = from.x + ratio * (to.x - from.x)
        let y = from.y + ratio * (to.y - from.y)

        return CGPoint(x: x, y: y)
    }
}