Add 2048 Game

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

@@ -0,0 +1,116 @@
+//
+//  BlockGridView.swift
+//  SwiftUI2048
+//
+//  Created by Hongyu on 6/5/19.
+//  Copyright © 2019 Cyandev. All rights reserved.
+//
+
+import SwiftUI
+
+fileprivate struct IdentifiableIndexedBlock : Identifiable {
+    
+    typealias ID = String
+    typealias IdentifiedValue = IndexedBlock<IdentifiedBlock>
+    
+    static var uniqueBlankId = 0
+    
+    let indexedBlock: IndexedBlock<IdentifiedBlock>
+    
+    var id: Self.ID {
+        if let id = indexedBlock.item?.id {
+            return "\(id)"
+        }
+        
+        // TODO: (Refactor) Don't mix two types of block views.
+        IdentifiableIndexedBlock.uniqueBlankId += 1
+        return "Blank_\(IdentifiableIndexedBlock.uniqueBlankId)"
+    }
+    
+    var identifiedValue: Self.IdentifiedValue {
+        return indexedBlock
+    }
+    
+}
+
+extension AnyTransition {
+    
+    static func blockAppear(from: Edge) -> AnyTransition {
+        return .asymmetric(
+            insertion: AnyTransition.opacity
+                .combined(with: .move(edge: from)),
+            removal: .identity)
+    }
+    
+}
+
+struct BlockGridView : View {
+    
+    typealias SupportingMatrix = BlockMatrix<IdentifiedBlock>
+    
+    let matrix: Self.SupportingMatrix
+    let blockEnterEdge: Edge
+    
+    func createBlock(_ block: IdentifiedBlock?) -> some View {
+        if let block = block {
+            return BlockView(number: block.number)
+        }
+        return BlockView.blank()
+    }
+    
+    // FIXME: This is existed as a workaround for a Swift compiler bug.
+    func zIndex(_ block: IdentifiedBlock?) -> Double {
+        if block == nil {
+            return 1
+        }
+        return 1000
+    }
+    
+    var body: some View {
+        ZStack {
+            ForEach(
+                self.matrix.flatten.map { IdentifiableIndexedBlock(indexedBlock: $0) }
+            ) { block in
+                self.createBlock(block.item)
+                    .frame(width: 65, height: 65, alignment: .center)
+                    .position(x: CGFloat(block.index.0) * (65 + 12) + 32.5 + 12,
+                              y: CGFloat(block.index.1) * (65 + 12) + 32.5 + 12)
+                    .zIndex(self.zIndex(block.item))
+                    .transition(.blockAppear(from: self.blockEnterEdge))
+                    .animation(block.item == nil ? nil : .spring(mass: 1, stiffness: 400, damping: 56, initialVelocity: 0))
+            }
+        }
+        .frame(width: 320, height: 320, alignment: .center)
+        .background(
+            Rectangle()
+                .fill(Color(red:0.72, green:0.66, blue:0.63, opacity:1.00))
+        )
+        .clipped()
+        .cornerRadius(6)
+    }
+    
+}
+
+#if DEBUG
+struct BlockGridView_Previews : PreviewProvider {
+    
+    static var matrix: BlockGridView.SupportingMatrix {
+        var _matrix = BlockGridView.SupportingMatrix()
+        _matrix.place(IdentifiedBlock(id: 1, number: 2), to: (2, 0))
+        _matrix.place(IdentifiedBlock(id: 2, number: 2), to: (3, 0))
+        _matrix.place(IdentifiedBlock(id: 3, number: 8), to: (1, 1))
+        _matrix.place(IdentifiedBlock(id: 4, number: 4), to: (2, 1))
+        _matrix.place(IdentifiedBlock(id: 5, number: 512), to: (3, 3))
+        _matrix.place(IdentifiedBlock(id: 6, number: 1024), to: (2, 3))
+        _matrix.place(IdentifiedBlock(id: 7, number: 16), to: (0, 3))
+        _matrix.place(IdentifiedBlock(id: 8, number: 8), to: (1, 3))
+        return _matrix
+    }
+    
+    static var previews: some View {
+        BlockGridView(matrix: matrix, blockEnterEdge: .top)
+            .previewLayout(.sizeThatFits)
+    }
+    
+}
+#endif