swiftui - SwiftUI 框架宽度问题

Question

我正在创建一个可滚动的选择栏。我想要文本下方的选择指示器以匹配其上方文本矩形的宽度。所以在下图中，红色将适合黑色区域的整个宽度。

import SwiftUI

struct TabSelectionView: View {
    let tabs: [String]
    @State var selectedIndex: Int
    
    var tabHeight: CGFloat = 40
    var tabHorizontalPadding: CGFloat = 8
    var tabVerticalPadding: CGFloat = 16
    var selectedTabColor = Color.primary
    var selectedTextColor = Color.white
    var unselectedTabColor = Color.gray
    var unselectedTextColor = Color.black
    var selectionBarColor = Color.red
    var selectionBarHeight: CGFloat = 4
    
    var body: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack(spacing: 0) {
                ForEach(0..<tabs.count, id: \.self) { index in
                    tabView(for: index)
                }
            }
        }
    }
    
    private func tabView(for index: Int) -> some View {
        let isSelected = index == selectedIndex
        let tabColor = isSelected ? selectedTabColor : unselectedTabColor
        let textColor = isSelected ? selectedTextColor : unselectedTextColor
        let barColor = isSelected ? selectionBarColor : unselectedTabColor
        
        return VStack(spacing: 0) {
            Text(tabs[index])
                .foregroundColor(textColor)
                .padding(.horizontal, tabHorizontalPadding)
                .padding(.vertical, tabVerticalPadding)
                .background(tabColor)
                .frame(height: tabHeight - selectionBarHeight)
            
            if selectionBarHeight > 0 {
                Rectangle()
                    .foregroundColor(barColor)
                    .frame(maxWidth: .infinity)
                    .frame(height: selectionBarHeight)
            }
        }
        .contentShape(Rectangle())
        .onTapGesture {
            selectedIndex = index
        }
        
    }
}

struct TabSelectionView_Previews: PreviewProvider {
    static var previews: some View {
        let tabs1 = ["All", "Grouping 1", "Grouping 2", "Grouping 3", "Sub Grouping 1", "Grouping 4", "Groupint 5", "Sub Grouping 2"]
                
        TabSelectionView(tabs: tabs1, selectedIndex: .constant(0))
            .previewLayout(PreviewLayout.sizeThatFits)
    }
}