Demo showing how to use GradientMap to modify the background of a picker to indicate severity of selection

PickerSeverityDemo.swift

//
//  PickerSeverityDemo.swift
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
//  of the Software, and to permit persons to whom the Software is furnished to do so,
//  subject to the following conditions:

//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
//  INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
//  PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
//  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
//  AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
//  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//  Created by Adam Fordyce on 23/01/2020.
//  Copyright © 2020 Adam Fordyce. All rights reserved.
//

import SwiftUI
import PureSwiftUITools

private let gradientMap = GradientMap([.pureGreen, .pureYellow, .pureRed], withResolution: 10)

struct PickerSeverityDemo: View {
    var choices = 0..<10
    @State private var choice = 5
    var body: some View {
        VStack {
            Picker("Severity Level", selection: self.$choice) {
                ForEach(choices) { choice in
                    Text((choice + 1).asString)
                        .width(50)
                        .backgroundColor(gradientMap[choice, default: .white])
                        .clipRoundedRectangleWithStroke(5, .black, lineWidth: 2)
                }
            }
            .labelsHidden()
            .scale(2)
        }
    }
}

struct PickerSeverityDemo_Previews: PreviewProvider {
    struct PickerSeverityDemo_Harness: View {

        var body: some View {
            PickerSeverityDemo()
        }
    }

    static var previews: some View {
        PickerSeverityDemo_Harness()
    }
}