Add spectate button + test

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiplayerSpectateButton.cs

@@ -0,0 +1,53 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using NUnit.Framework;
+using osu.Framework.Graphics;
+using osu.Game.Online.Multiplayer;
+using osu.Game.Screens.OnlinePlay.Multiplayer.Match;
+using osuTK;
+using osuTK.Input;
+
+namespace osu.Game.Tests.Visual.Multiplayer
+{
+    public class TestSceneMultiplayerSpectateButton : MultiplayerTestScene
+    {
+        private MultiplayerSpectateButton button;
+        private IDisposable readyClickOperation;
+
+        [SetUp]
+        public new void Setup() => Schedule(() =>
+        {
+            Child = button = new MultiplayerSpectateButton
+            {
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                Size = new Vector2(200, 50),
+                OnSpectateClick = async () =>
+                {
+                    readyClickOperation = OngoingOperationTracker.BeginOperation();
+                    await Client.ToggleSpectate();
+                    readyClickOperation.Dispose();
+                }
+            };
+        });
+
+        [TestCase(MultiplayerUserState.Idle)]
+        [TestCase(MultiplayerUserState.Ready)]
+        public void TestToggleWhenIdle(MultiplayerUserState initialState)
+        {
+            addClickButtonStep();
+            AddAssert("user is spectating", () => Client.Room?.Users[0].State == MultiplayerUserState.Spectating);
+
+            addClickButtonStep();
+            AddAssert("user is idle", () => Client.Room?.Users[0].State == MultiplayerUserState.Idle);
+        }
+
+        private void addClickButtonStep() => AddStep("click button", () =>
+        {
+            InputManager.MoveMouseTo(button);
+            InputManager.Click(MouseButton.Left);
+        });
+    }
+}

osu.Game/Online/Multiplayer/StatefulMultiplayerClient.cs

@@ -249,6 +249,33 @@ public async Task ToggleReady()
             }
         }
 
+        /// <summary>
+        /// Toggles the <see cref="LocalUser"/>'s spectating state.
+        /// </summary>
+        /// <exception cref="InvalidOperationException">If a toggle of the spectating state is not valid at this time.</exception>
+        public async Task ToggleSpectate()
+        {
+            var localUser = LocalUser;
+
+            if (localUser == null)
+                return;
+
+            switch (localUser.State)
+            {
+                case MultiplayerUserState.Idle:
+                case MultiplayerUserState.Ready:
+                    await ChangeState(MultiplayerUserState.Spectating).ConfigureAwait(false);
+                    return;
+
+                case MultiplayerUserState.Spectating:
+                    await ChangeState(MultiplayerUserState.Idle).ConfigureAwait(false);
+                    return;
+
+                default:
+                    throw new InvalidOperationException($"Cannot toggle spectate when in {localUser.State}");
+            }
+        }
+
         public abstract Task TransferHost(int userId);
 
         public abstract Task ChangeSettings(MultiplayerRoomSettings settings);

osu.Game/Screens/OnlinePlay/Multiplayer/Match/MultiplayerSpectateButton.cs

@@ -0,0 +1,92 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Diagnostics;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Backgrounds;
+using osu.Game.Graphics.UserInterface;
+using osu.Game.Online.Multiplayer;
+using osuTK;
+
+namespace osu.Game.Screens.OnlinePlay.Multiplayer.Match
+{
+    public class MultiplayerSpectateButton : MultiplayerRoomComposite
+    {
+        public Action OnSpectateClick
+        {
+            set => button.Action = value;
+        }
+
+        [Resolved]
+        private OngoingOperationTracker ongoingOperationTracker { get; set; }
+
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        private IBindable<bool> operationInProgress;
+
+        private readonly ButtonWithTrianglesExposed button;
+
+        public MultiplayerSpectateButton()
+        {
+            InternalChild = button = new ButtonWithTrianglesExposed
+            {
+                RelativeSizeAxes = Axes.Both,
+                Size = Vector2.One,
+                Enabled = { Value = true },
+            };
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            operationInProgress = ongoingOperationTracker.InProgress.GetBoundCopy();
+            operationInProgress.BindValueChanged(_ => updateState());
+        }
+
+        protected override void OnRoomUpdated()
+        {
+            base.OnRoomUpdated();
+
+            updateState();
+        }
+
+        private void updateState()
+        {
+            var localUser = Client.LocalUser;
+
+            if (localUser == null)
+                return;
+
+            Debug.Assert(Room != null);
+
+            switch (localUser.State)
+            {
+                default:
+                    button.Text = "Spectate";
+                    button.BackgroundColour = colours.Blue;
+                    button.Triangles.ColourDark = colours.Blue;
+                    button.Triangles.ColourLight = colours.BlueLight;
+                    break;
+
+                case MultiplayerUserState.Spectating:
+                    button.Text = "Stop spectating";
+                    button.BackgroundColour = colours.Red;
+                    button.Triangles.ColourDark = colours.Red;
+                    button.Triangles.ColourLight = colours.RedLight;
+                    break;
+            }
+
+            button.Enabled.Value = Client.Room?.State == MultiplayerRoomState.Open && !operationInProgress.Value;
+        }
+
+        private class ButtonWithTrianglesExposed : TriangleButton
+        {
+            public new Triangles Triangles => base.Triangles;
+        }
+    }
+}