[KOA-5084] BPKStarRating SwiftUI (#1632)

* initial setup

* Star Rating component

* addressing pr comments

* added hotel star ratings to readme

Backpack-SwiftUI/StarRating/Classes/BPKHotelStarRating.swift

@@ -0,0 +1,62 @@
+/*
+ * Backpack - Skyscanner's Design System
+ *
+ * Copyright 2018 Skyscanner Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import SwiftUI
+
+/// A view that displays a star rating based on a rating value.
+public struct BPKHotelStarRating: View {
+    @Binding private var rating: Int
+    private let size: BPKStarRatingSize
+
+    /// Initializes a new `BPKHotelStarRating` instance.
+    /// - Parameters:
+    ///   - rating: A binding to the current rating value.
+    ///   Represents the number of stars to display.
+    ///   - size: The size of the star rating, defaults to `.small`.
+    public init(
+        rating: Binding<Int>,
+        size: BPKStarRatingSize = .small
+    ) {
+        self._rating = rating
+        self.size = size
+    }
+
+    public var body: some View {
+        HStack(spacing: 0) {
+            ForEach(0..<rating, id: \.self) { index in
+                BPKStarView(type: .full, size: size.starSize)
+                    .accessibilityHidden(true)
+            }
+        }
+        .accessibilityElement()
+        .accessibilityValue(Text(String(rating)))
+    }
+}
+
+struct BPKHotelStarRating_Previews: PreviewProvider {
+    static var previews: some View {
+        VStack(alignment: .leading) {
+            BPKText("Small", style: .heading3)
+            BPKHotelStarRating(rating: .constant(3))
+            BPKHotelStarRating(rating: .constant(4))
+            BPKText("Large", style: .heading3)
+            BPKHotelStarRating(rating: .constant(3), size: .large)
+            BPKHotelStarRating(rating: .constant(4), size: .large)
+        }
+    }
+}

Backpack-SwiftUI/StarRating/Classes/BPKStarRating.swift

@@ -0,0 +1,125 @@
+/*
+ * Backpack - Skyscanner's Design System
+ *
+ * Copyright 2018 Skyscanner Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import SwiftUI
+
+/// A view that displays a star rating based on a rating value.
+public struct BPKStarRating: View {
+    /// An enum representing the rounding method to use.
+    /// - down: Rounds down to the nearest half star.
+    /// - up: Rounds up to the nearest half star.
+    /// - nearest: Rounds to the nearest half star.
+    public enum Rounding {
+        case down, up, nearest
+
+        func roundedRating(_ rating: Float) -> Float {
+            switch self {
+            case .down: return floor(rating * 2) / 2
+            case .up: return ceil(rating * 2) / 2
+            case .nearest: return round(rating * 2) / 2
+            }
+        }
+    }
+
+    @Binding private var rating: Float
+    private let maxRating: Int
+    private let size: BPKStarRatingSize
+    private let rounding: Rounding
+    private let onRatingChanged: ((Float) -> Void)?
+
+    /// Initializes a new `BPKStarRating` instance.
+    /// - Parameters:
+    ///   - rating: A binding to the current rating value.
+    ///   - maxRating: The maximum rating value allowed.
+    ///   Represents the number of stars to display.
+    ///   - size: The size of the star rating, defaults to `.small`.
+    ///   - rounding: The rounding method to use, defaults to `.down`.
+    ///   - onRatingChanged: A callback that is called when the user taps on a star.
+    public init(
+        rating: Binding<Float>,
+        maxRating: Int,
+        size: BPKStarRatingSize = .small,
+        rounding: Rounding = .down,
+        onRatingChanged: ((Float) -> Void)? = nil
+    ) {
+        self._rating = rating
+        self.maxRating = maxRating
+        self.size = size
+        self.rounding = rounding
+        self.onRatingChanged = onRatingChanged
+    }
+
+    public var body: some View {
+        HStack(spacing: 0) {
+            ForEach(0..<maxRating, id: \.self) { index in
+                BPKStarView(type: starType(for: index), size: size.starSize)
+                    .onTapGesture {
+                        onRatingChanged?(Float(index + 1))
+                    } .accessibilityHidden(true)
+            }
+        }
+        .accessibilityElement()
+        .accessibilityValue(Text(String(coercedRating)))
+        .if(onRatingChanged != nil) { view in
+            view.accessibilityAdjustableAction { direction in
+                switch direction {
+                case .increment: increment()
+                case .decrement: decrement()
+                @unknown default: break
+                }
+            }
+        }
+    }
+
+    private func increment() {
+        onRatingChanged?(Float(min(maxRating, Int(coercedRating + 1))))
+    }
+
+    private func decrement() {
+        onRatingChanged?(Float(max(0, Int(coercedRating - 1))))
+    }
+
+    private func starType(for index: Int) -> BPKStarView.StarType {
+        let clamped = max(0, min(coercedRating - Float(index), 1))
+        switch clamped {
+        case 0..<0.5: return .empty
+        case 0.5..<1: return .half
+        default: return .full
+        }
+    }
+
+    private var coercedRating: Float {
+        let coercedRating = max(0, min(Float(maxRating), rating))
+        return rounding.roundedRating(coercedRating)
+    }
+}
+
+struct BPKStarRating_Previews: PreviewProvider {
+    static var previews: some View {
+        VStack(alignment: .leading) {
+            BPKText("Small", style: .heading3)
+            BPKStarRating(rating: .constant(3), maxRating: 5)
+            BPKStarRating(rating: .constant(3.5), maxRating: 5)
+            BPKStarRating(rating: .constant(4), maxRating: 5)
+            BPKText("Large", style: .heading3)
+            BPKStarRating(rating: .constant(3), maxRating: 5, size: .large)
+            BPKStarRating(rating: .constant(3.5), maxRating: 5, size: .large)
+            BPKStarRating(rating: .constant(4), maxRating: 5, size: .large)
+        }
+    }
+}

Backpack-SwiftUI/StarRating/Classes/BPKStarRatingSize.swift

@@ -0,0 +1,29 @@
+/*
+ * Backpack - Skyscanner's Design System
+ *
+ * Copyright 2018 Skyscanner Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/// An enum representing the size of the star rating.
+public enum BPKStarRatingSize {
+    case small, large
+
+    var starSize: BPKIcon.Size {
+        switch self {
+        case .small: return .small
+        case .large: return .large
+        }
+    }
+}

Backpack-SwiftUI/StarRating/Classes/BPKStarView.swift

@@ -0,0 +1,68 @@
+/*
+ * Backpack - Skyscanner's Design System
+ *
+ * Copyright 2018 Skyscanner Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import SwiftUI
+
+struct BPKStarView: View {
+    enum StarType {
+        case empty, half, full
+
+        var iconName: BPKIcon {
+            switch self {
+            case .empty: return .starOutline
+            case .half: return .starHalf
+            case .full: return .star
+            }
+        }
+
+        var color: BPKColor {
+            switch self {
+            case .empty: return .textDisabledColor
+            case .half: return .statusWarningSpotColor
+            case .full: return .statusWarningSpotColor
+            }
+        }
+    }
+
+    let type: StarType
+    let size: BPKIcon.Size
+
+    var body: some View {
+        BPKIconView(type.iconName, size: size)
+            .foregroundColor(type.color)
+    }
+}
+
+struct BPKStarView_Previews: PreviewProvider {
+    static var previews: some View {
+        VStack{
+            HStack {
+                BPKText("Large", style: .heading3)
+                BPKStarView(type: .empty, size: .large)
+                BPKStarView(type: .half, size: .large)
+                BPKStarView(type: .full, size: .large)
+            }
+            HStack {
+                BPKText("Small", style: .heading3)
+                BPKStarView(type: .empty, size: .small)
+                BPKStarView(type: .half, size: .small)
+                BPKStarView(type: .full, size: .small)
+            }
+        }
+    }
+}

Backpack-SwiftUI/StarRating/README.md

@@ -0,0 +1,52 @@
+# Backpack-SwiftUI/StarRating
+
+[![Cocoapods](https://img.shields.io/cocoapods/v/Backpack-SwiftUI.svg?style=flat)](hhttps://cocoapods.org/pods/Backpack-SwiftUI)
+[![class reference](https://img.shields.io/badge/Class%20reference-iOS-blue)](https://backpack.github.io/ios/versions/latest/swiftui/Structs/BPKStarRating.html)
+[![view on Github](https://img.shields.io/badge/Source%20code-GitHub-lightgrey)](https://github.com/Skyscanner/backpack-ios/tree/main/Backpack-SwiftUI/StarRating)
+
+| Day | Night |
+| --- | --- |
+| <img src="https://raw.githubusercontent.com/Skyscanner/backpack-ios/main/screenshots/iPhone-swiftui_star-rating___all_lm.png" alt="" width="375" /> |<img src="https://raw.githubusercontent.com/Skyscanner/backpack-ios/main/screenshots/iPhone-swiftui_star-rating___all_dm.png" alt="" width="375" /> |
+
+## Usage
+
+To use the star rating component in your code you will need to bind the `rating` property and set the `maxRating` property. The `maxRating` is the maximum number of stars that can be displayed.
+
+### Basic star rating
+
+```swift
+@State var rating: Float = 3.5
+BPKStarRating(rating: $rating, maxRating: 5)
+```
+
+### Interactive star rating
+
+```swift
+@State var rating: Float = 3.5
+BPKStarRating(rating: $rating, maxRating: 5) { selectedRating in
+    rating = selectedRating
+}
+```
+
+### Hotel star rating
+
+```swift
+@State var hotelRating: Int = 3
+BPKHotelStarRating(rating: $hotelRating)
+```
+
+### Star rating with Large size
+
+```swift
+@State var rating: Float = 3.5
+BPKStarRating(rating: $rating, maxRating: 5, size: .large)
+```
+
+### Customise Rating Rounding
+
+Rounding can be customised by setting the `rounding` property. The default is `.down`.
+
+```swift
+@State var rating: Float = 3.5
+BPKStarRating(rating: $rating, maxRating: 5, rounding: .down)
+```