ColorConverter.swift

ColorConverter.swift

import SwiftUI
import RegexBuilder
import PlaygroundSupport

enum ColorCode {
    /// 6文字および8文字のカラーコードの正規表現
    /// /^#?([0-9A-Fa-f]{2})([0-9A-Fa-f]{2})([0-9A-Fa-f]{2})([0-9A-Fa-f]{2})?$/
    private static let hexCapture = Capture { Repeat(count: 2) { .hexDigit } }
    private static let pattern8 = Regex {
        Optionally { "#" }
        hexCapture // R
        hexCapture // G
        hexCapture // B
        Optionally { hexCapture } // A
    }

    /// 3文字のカラーコードの正規表現
    /// /^#?([0-9A-Fa-f])([0-9A-Fa-f])([0-9A-Fa-f])$/
    private static let pattern3 = Regex {
        Optionally { "#" }
        Capture { .hexDigit } // R
        Capture { .hexDigit } // G
        Capture { .hexDigit } // B
    }

    /// カラーコードをRGB値に変換
    /// - Parameter hexStr: カラーコード
    /// - Returns: RGB値
    static func convert(from hexStr: String) -> (r: CGFloat, g: CGFloat, b: CGFloat, a: CGFloat)? {
        // 6文字および8文字
        if let match = hexStr.wholeMatch(of: pattern8) {
            let (_, r, g, b, a) = match.output
            return (toDecimal(r), toDecimal(g), toDecimal(b), toDecimal(a ?? "ff"))
        }
        // 3文字
        if let match = hexStr.wholeMatch(of: pattern3) {
            let (_, r, g, b) = match.output
            return (toDecimal(r), toDecimal(g), toDecimal(b), 1.0)
        }
        return nil
    }

    /// 16進をカラー値に変換
    /// - Parameter hex: 16進 (文字列)
    /// - Returns: カラー値
    private static func toDecimal(_ hex: Substring) -> CGFloat {
        let h: String = hex.count == 1 ? .init(repeating: .init(hex), count: 2) : .init(hex)
        return .init(Int(h, radix: 16) ?? 0) / 255.0
    }
}

struct ColorConverter: View {
    /// カラーコード入力
    @State private var colorCode: String = ""

    /// UIColorの出力
    @State private var uiColorString: String = ""

    /// Colorの出力
    @State private var colorString: String = ""

    /// パレットのカラー
    @State private var color: Color?

    /// body
    var body: some View {
        HStack {
            RoundedRectangle(cornerRadius: 8)
                .fill(color ?? .black)
                .frame(width: 80, height: 80)
            VStack {
                TextField("カラーコード", text: $colorCode)
                    .textFieldStyle(RoundedBorderTextFieldStyle())
                TextField("UIColor", text: .constant(uiColorString), axis: .vertical)
                    .textSelection(.enabled)
                    .font(.caption)
                    .frame(maxHeight: .infinity)
                TextField("Color", text: .constant(colorString), axis: .vertical)
                    .textSelection(.enabled)
                    .font(.caption)
                    .frame(maxHeight: .infinity)
            }
        }
        .frame(width: 400, height: 150)
        .padding()
        .onChange(of: colorCode, perform: convert)
    }

    /// 出力
    private func convert(_ colorCode: String) {
        if let c = ColorCode.convert(from: colorCode) {
            uiColorString = "UIColor(red: \(c.r), green: \(c.g), blue: \(c.b), alpha: \(c.a))"
            colorString = "Color(red: \(c.r), green: \(c.g), blue: \(c.b), opacity: \(c.a))"
            color = .init(red: c.r, green: c.g, blue: c.b, opacity: c.a)
        } else {
            uiColorString = ""
            colorString = ""
            color = nil
        }
    }
}

PlaygroundPage.current.setLiveView(ColorConverter())