Add 2048 Game

Examples/2048 Game/SwiftUI2048/Views/GameView.swift

@@ -0,0 +1,127 @@
+//
+//  GameView.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import SwiftUI
+
+extension Edge {
+    
+    static func from(_ from: GameLogic.Direction) -> Self {
+        switch from {
+        case .down:
+            return .top
+        case .up:
+            return .bottom
+        case .left:
+            return .trailing
+        case .right:
+            return .leading
+        }
+    }
+    
+}
+
+struct GameView : View {
+    
+    @State var gestureStartLocation: CGPoint = .zero
+    @State var lastGestureDirection: GameLogic.Direction = .up
+    @EnvironmentObject var gameLogic: GameLogic
+    
+    fileprivate struct LayoutTraits {
+        let bannerOffset: CGSize
+        let containerAlignment: Alignment
+    }
+    
+    fileprivate func layoutTraits(`for` proxy: GeometryProxy) -> LayoutTraits {
+        let landscape = proxy.size.width > proxy.size.height
+        
+        return LayoutTraits(
+            bannerOffset: landscape
+                ? .init(width: proxy.safeAreaInsets.leading + 32, height: 0)
+                : .init(width: 0, height: proxy.safeAreaInsets.top + 32),
+            containerAlignment: landscape ? .leading : .top
+        )
+    }
+    
+    var gesture: some Gesture {
+        let threshold: CGFloat = 44
+        let drag = DragGesture()
+            .onChanged { v in
+                guard self.gestureStartLocation != v.startLocation else { return }
+                
+                withTransaction(Transaction()) {
+                    self.gestureStartLocation = v.startLocation
+                    
+                    if v.translation.width > threshold {
+                        // Move right
+                        self.gameLogic.move(.right)
+                        self.lastGestureDirection = .right
+                    } else if v.translation.width < -threshold {
+                        // Move left
+                        self.gameLogic.move(.left)
+                        self.lastGestureDirection = .left
+                    } else if v.translation.height > threshold {
+                        // Move down
+                        self.gameLogic.move(.down)
+                        self.lastGestureDirection = .down
+                    } else if v.translation.height < -threshold {
+                        // Move up
+                        self.gameLogic.move(.up)
+                        self.lastGestureDirection = .up
+                    } else {
+                        // Direction cannot be deduced, reset gesture state.
+                        self.gestureStartLocation = .zero
+                    }
+                }
+                
+                // After the scene is updated, reset the last gesture direction
+                // to make sure the animation is right when user starts a new
+                // game.
+                OperationQueue.main.addOperation {
+                    self.lastGestureDirection = .up
+                }
+            }
+        return drag
+    }
+    
+    var body: some View {
+        GeometryReader { proxy in
+            bind(self.layoutTraits(for: proxy)) { layoutTraits in
+                ZStack(alignment: layoutTraits.containerAlignment) {
+                    Text("2048")
+                        .font(Font.system(size: 48).weight(.black))
+                        .color(Color(red:0.47, green:0.43, blue:0.40, opacity:1.00))
+                        .offset(layoutTraits.bannerOffset)
+                    
+                    ZStack(alignment: .top) {
+                        BlockGridView(matrix: self.gameLogic.blockMatrix,
+                                      blockEnterEdge: .from(self.lastGestureDirection))
+                            .gesture(self.gesture)
+                        }
+                        .frame(width: proxy.size.width, height: proxy.size.height, alignment: .center)
+                    }
+                    .frame(width: proxy.size.width, height: proxy.size.height, alignment: .center)
+                    .background(
+                        Rectangle().fill(Color(red:0.96, green:0.94, blue:0.90, opacity:1.00))
+                )
+            }
+        }
+        .edgesIgnoringSafeArea(.all)
+    }
+    
+}
+
+#if DEBUG
+struct GameView_Previews : PreviewProvider {
+    
+    static var previews: some View {
+        GameView()
+            .environmentObject(GameLogic())
+    }
+    
+}
+#endif