SFEdgeShape

SFEdgeShape.swift

import SwiftUI
import Vision

@available(iOS 17, *)
public struct SFEdgeShape: InsettableShape {
    public init(systemName: String) {
        self.systemName = systemName
    }

    var systemName: String
    var insetAmount: CGFloat = 0

    nonisolated var trimmedImage: UIImage? {
        let cfg = UIImage.SymbolConfiguration(pointSize: 256.0)
        let img = UIImage(systemName: systemName, withConfiguration: cfg)?.withTintColor(.black, renderingMode: .alwaysOriginal)
        guard let imgA = img else {
            return nil
        }
        guard let cgRef = imgA.cgImage else {
            return nil
        }
        let imgB = UIImage(cgImage: cgRef, scale: imgA.scale, orientation: imgA.imageOrientation)
            .withTintColor(.black, renderingMode: .alwaysOriginal)
        let resultImage = UIGraphicsImageRenderer(size: imgB.size).image { ctx in
            UIColor.white.setFill()
            ctx.fill(CGRect(origin: .zero, size: imgB.size))
            imgB.draw(at: .zero)
        }
        return resultImage
    }

    public func path(in rect: CGRect) -> Path {
        guard let inputImage = self.trimmedImage
        else {
            return Path()
        }
        guard let cgPath = detectVisionContours(from: inputImage) else { return Path() }
        let scW: CGFloat = (rect.width - CGFloat(insetAmount)) / cgPath.boundingBox.width
        let scH: CGFloat = (rect.height - CGFloat(insetAmount)) / cgPath.boundingBox.height

        // we need to invert the Y-coordinate space
        var transform = CGAffineTransform.identity
            .scaledBy(x: scW, y: -scH)
            .translatedBy(x: 0.0, y: -cgPath.boundingBox.height)

        if let imagePath = cgPath.copy(using: &transform) {
            return Path(imagePath)
        } else {
            return Path()
        }
    }

    nonisolated public func inset(by amount: CGFloat) -> some InsettableShape {
        var shape = self
        shape.insetAmount += amount
        return shape
    }

    nonisolated func detectVisionContours(from sourceImage: UIImage) -> CGPath? {
        let inputImage = CIImage.init(cgImage: sourceImage.cgImage!)
        let contourRequest = VNDetectContoursRequest()
        contourRequest.revision = VNDetectContourRequestRevision1
        contourRequest.contrastAdjustment = 1.0
        contourRequest.maximumImageDimension = 512

        let requestHandler = VNImageRequestHandler(ciImage: inputImage, options: [:])
        try? requestHandler.perform([contourRequest])
        return contourRequest.results?.first?.normalizedPath
    }
}