[SwiftUI] Text style buttons

TextStyleButtons.swift

//
//  ContentView.swift
//  TestsWithSwiftUI
//
//  Created by Thiago Holanda on 01.07.19.
//  Copyright © 2019 unnamedd codes. All rights reserved.
//

import SwiftUI

struct ContentView : View {
    @State var isBold: Bool          = false
    @State var isItalic: Bool        = false
    @State var isUnderline: Bool     = false
    @State var isStrikethrough: Bool = false
    
    let size: TextStyleButton.Size = (width: 40, height: 30)
    
    var body: some View {
        HStack(spacing: 2.0) {
            
            TextStyleButton(
                state: $isBold,
                textStyle: .bold,
                size: size
            )
            
            TextStyleButton(
                state: $isItalic,
                textStyle: .italic,
                size: size
            )
            
            TextStyleButton(
                state: $isUnderline,
                textStyle: .underline,
                size: size,
                offset: (x: 0, y: 2)
            )
            
            TextStyleButton(
                state: $isStrikethrough,
                textStyle: .strikethrough,
                size: size
            )
        }.cornerRadius(5)
    }
}

enum TextStyle: String, CaseIterable {
    case bold
    case italic
    case strikethrough
    case underline
}

struct TextStyleButton: View {
    typealias Size = (width: Length, height: Length)
    typealias Offset = (x: Length, y: Length)
    
    @Binding var state: Bool

    var textStyle: TextStyle
    var size: Size
    var offset: Offset = (x: 0, y: 0)
    
    var body: some View {
        Button(action: {
            print("Toggle it - \(self.textStyle.rawValue)")
            self.$state.value.toggle()
        }) {
            Image(systemName: textStyle.rawValue)
                .imageScale(.medium)
                .foregroundColor(self.state ? .white : .black)
                .font(.headline)
                .frame(width: size.width, height: size.height)
                .offset(x: self.offset.x, y: self.offset.y)
            }
            .background(self.state ? Color.gray : Color.yellow)
    }
}

#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        ContentView()
        .previewLayout(.fixed(width: 200, height: 50))
    }
}
#endif