Allow gestures to go outside of board view

Tetris/Assets.xcassets/TempBackground.colorset/Contents.json

@@ -0,0 +1,38 @@
+{
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  },
+  "colors" : [
+    {
+      "idiom" : "universal",
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "red" : "1.000",
+          "alpha" : "1.000",
+          "blue" : "1.000",
+          "green" : "1.000"
+        }
+      }
+    },
+    {
+      "idiom" : "universal",
+      "appearances" : [
+        {
+          "appearance" : "luminosity",
+          "value" : "dark"
+        }
+      ],
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "red" : "0.000",
+          "alpha" : "1.000",
+          "blue" : "0.000",
+          "green" : "0.000"
+        }
+      }
+    }
+  ]
+}

Tetris/ContentView.swift

@@ -17,6 +17,7 @@ struct ContentView: View {
         return c
     }()
     @State var timer: Timer?
+    @State var gestureState: GestureState = .none
     @State var initialXPosition: Int?
 
     var body: some View {
@@ -40,7 +41,6 @@ struct ContentView: View {
                         .onAppear(perform: self.startTimer)
                         .onDisappear(perform: self.stopTimer)
                         .onTapGesture(perform: self.onTap)
-                        .gesture(self.horizDragGesture(geometry: geometry).simultaneously(with: self.verticalDragGesture))
                     //        .gesture(ExclusiveGesture(horizDragGesture, verticalDragGesture))
                     //            .gesture(horizDragGesture.simultaneously(with: verticalDragGesture))
                     
@@ -50,6 +50,8 @@ struct ContentView: View {
                     }
                         .padding(.trailing, 8)
                 }
+                    .background(Color("TempBackground")) // visually does nothing but lets the gesture work outside of the board, see FB7385742
+                    .gesture(self.horizDragGesture(geometry: geometry).simultaneously(with: self.verticalDragGesture))
                 Spacer()
                 HStack {
                     Button(action: { self.controller.rotate(direction: .counterClockwise) }) {
@@ -73,26 +75,40 @@ struct ContentView: View {
     func horizDragGesture(geometry: GeometryProxy) -> some Gesture {
         DragGesture(coordinateSpace: .global)
             .onChanged { (state) in
-                guard case .playing(.normal) = self.controller.state,
+                guard self.gestureState != .vertical,
+                    case .playing(.normal) = self.controller.state,
                     let currentPiece = self.controller.currentPiece else { return }
                 if self.initialXPosition == nil {
                     self.initialXPosition = currentPiece.topLeft.0
                 }
                 var moved = currentPiece
                 let xPosition = self.initialXPosition! + Int((state.translation.width / (geometry.size.width / 10)).rounded())
+                
+                if xPosition != self.initialXPosition {
+                    self.gestureState = .horizontal
+                }
                 moved.topLeft = (xPosition, currentPiece.topLeft.1)
                 if !self.controller.overlapsAny(moved) {
                     self.controller.currentPiece = moved
                 }
             }.onEnded { (state) in
                 self.initialXPosition = nil
+                if self.gestureState == .horizontal {
+                    self.gestureState = .none
+                }
             }
     }
     
     var verticalDragGesture: some Gesture {
         DragGesture()
+            .onChanged({ (state) in
+                guard self.gestureState != .horizontal else { return }
+                
+            })
             .onEnded { (state) in
+                guard self.gestureState != .horizontal else { return }
                 if abs(state.translation.height) > 80 {
+                    self.gestureState = .none
                     if state.translation.height > 0 {
                         self.onSwipeDown()
                     } else {
@@ -133,6 +149,10 @@ struct ContentView: View {
     }
 }
 
+enum GestureState: Equatable {
+    case none, horizontal, vertical
+}
+
 struct ContentView_Previews: PreviewProvider {
     static var previews: some View {
         ContentView()