Add the ability to switch between tabs using keyboard controls

osu.Framework.Tests/Visual/TestCaseTabControl.cs

@@ -11,6 +11,7 @@
 using osu.Framework.Graphics.Sprites;
 using osu.Framework.Graphics.UserInterface;
 using osu.Framework.Testing;
+using osu.Framework.Input;
 using OpenTK;
 using OpenTK.Graphics;
 
@@ -33,15 +34,27 @@ public TestCaseTabControl()
 
             StyledTabControl pinnedAndAutoSort = new StyledTabControl
             {
-                Position = new Vector2(500, 50),
+                Position = new Vector2(200, 150),
                 Size = new Vector2(200, 30),
                 AutoSort = true
             };
             items.GetRange(0, 7).AsEnumerable().ForEach(item => pinnedAndAutoSort.AddItem(item.Value));
             pinnedAndAutoSort.PinItem(TestEnum.Test5);
 
+            StyledTabControl switchingTabControl;
+            PlatformActionContainer platformActionContainer = new PlatformActionContainer
+            {
+                Child = switchingTabControl = new StyledTabControl
+                {
+                    Position = new Vector2(200, 250),
+                    Size = new Vector2(200, 30),
+                }
+            };
+            items.AsEnumerable().ForEach(item => switchingTabControl.AddItem(item.Value));
+
             Add(simpleTabcontrol);
             Add(pinnedAndAutoSort);
+            Add(platformActionContainer);
 
             var nextTest = new Func<TestEnum>(() => items.AsEnumerable()
                                                          .Select(item => item.Value)
@@ -80,6 +93,19 @@ public TestCaseTabControl()
             {
                 if (pinned.Count > 0) pinnedAndAutoSort.UnpinItem(pinned.Pop());
             });
+
+            AddStep("Set first tab", () => switchingTabControl.Current.Value = switchingTabControl.VisibleItems.First());
+            AddStep("Switch forward", () => platformActionContainer.TriggerPressed(new PlatformAction(PlatformActionType.DocumentNext)));
+            AddAssert("Ensure second tab", () => switchingTabControl.Current.Value == switchingTabControl.VisibleItems.ElementAt(1));
+
+            AddStep("Switch backward", () => platformActionContainer.TriggerPressed(new PlatformAction(PlatformActionType.DocumentPrevious)));
+            AddAssert("Ensure first Tab", () => switchingTabControl.Current.Value == switchingTabControl.VisibleItems.First());
+
+            AddStep("Switch backward", () => platformActionContainer.TriggerPressed(new PlatformAction(PlatformActionType.DocumentPrevious)));
+            AddAssert("Ensure last tab", () => switchingTabControl.Current.Value == switchingTabControl.VisibleItems.Last());
+
+            AddStep("Switch forward", () => platformActionContainer.TriggerPressed(new PlatformAction(PlatformActionType.DocumentNext)));
+            AddAssert("Ensure first tab", () => switchingTabControl.Current.Value == switchingTabControl.VisibleItems.First());
         }
 
         private class StyledTabControl : TabControl<TestEnum>

osu.Framework/Graphics/UserInterface/TabControl.cs

@@ -8,6 +8,8 @@
 using osu.Framework.Configuration;
 using osu.Framework.Extensions;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Input;
+using osu.Framework.Input.Bindings;
 using OpenTK;
 
 namespace osu.Framework.Graphics.UserInterface
@@ -19,7 +21,7 @@ namespace osu.Framework.Graphics.UserInterface
     /// start of the list.
     /// </summary>
     /// <typeparam name="T">The type of item to be represented by tabs.</typeparam>
-    public abstract class TabControl<T> : Container, IHasCurrentValue<T>
+    public abstract class TabControl<T> : Container, IHasCurrentValue<T>, IKeyBindingHandler<PlatformAction>
     {
         public Bindable<T> Current { get; } = new Bindable<T>();
 
@@ -28,6 +30,8 @@ public abstract class TabControl<T> : Container, IHasCurrentValue<T>
         /// </summary>
         public IEnumerable<T> Items => TabContainer.TabItems.Select(t => t.Value).Concat(Dropdown.Items.Select(kvp => kvp.Value)).Distinct();
 
+        public IEnumerable<T> VisibleItems => TabContainer.TabItems.Select(t => t.Value).Distinct();
+
         /// <summary>
         /// When true, tabs selected from the overflow dropdown will be moved to the front of the list (after pinned items).
         /// </summary>
@@ -41,6 +45,11 @@ public abstract class TabControl<T> : Container, IHasCurrentValue<T>
 
         protected TabItem<T> SelectedTab;
 
+        /// <summary>
+        /// When true, tabs can be switched back and forth using PlatformAction.DocumentPrevious and PlatformAction.DocumentNext respectively.
+        /// </summary>
+        public virtual bool IsSwitchable => true;
+
         /// <summary>
         /// Creates an optional overflow dropdown.
         /// When implementing this dropdown make sure:
@@ -237,6 +246,35 @@ protected virtual void SelectTab(TabItem<T> tab)
             Current.Value = SelectedTab.Value;
         }
 
+        public virtual void SwitchTab(int offset, bool wrap = true)
+        {
+            TabItem<T>[] switchableTabs = TabContainer.TabItems.Where(tab => tab.IsSwitchable).ToArray();
+            int tabCount = switchableTabs.Length;
+
+            if (tabCount == 0)
+                return;
+
+            if (tabCount == 1 || SelectedTab == null)
+            {
+                SelectTab(switchableTabs[0]);
+                return;
+            }
+
+            int selectedIndex = Array.IndexOf(switchableTabs, SelectedTab);
+            int targetIndex = selectedIndex + offset;
+
+            if (wrap)
+            {
+                targetIndex = targetIndex % tabCount;
+                if (targetIndex < 0)
+                    targetIndex += tabCount;
+            }
+
+            targetIndex = Math.Min(tabCount - 1, Math.Max(0, targetIndex));
+
+            SelectTab(switchableTabs[targetIndex]);
+        }
+
         private void performTabSort(TabItem<T> tab)
         {
             TabContainer.SetLayoutPosition(tab, getTabDepth(tab));
@@ -248,6 +286,26 @@ private void performTabSort(TabItem<T> tab)
 
         private float getTabDepth(TabItem<T> tab) => tab.Pinned ? float.MinValue : --depthCounter;
 
+        public bool OnPressed(PlatformAction action)
+        {
+            if (IsSwitchable)
+            {
+                switch (action.ActionType)
+                {
+                    case PlatformActionType.DocumentNext:
+                        SwitchTab(1);
+                        return true;
+
+                    case PlatformActionType.DocumentPrevious:
+                        SwitchTab(-1);
+                        return true;
+                }
+            }
+            return false;
+        }
+
+        public bool OnReleased(PlatformAction action) => false;
+
         protected virtual TabFillFlowContainer CreateTabFlow() => new TabFillFlowContainer
         {
             Direction = FillDirection.Full,

osu.Framework/Graphics/UserInterface/TabItem.cs

@@ -26,6 +26,11 @@ public abstract class TabItem<T> : TabItem
 
         public override bool IsRemovable => false;
 
+        /// <summary>
+        /// When true, this tab can be switched to using PlatformAction.DocumentPrevious and PlatformAction.DocumentNext. Otherwise, it will be skipped.
+        /// </summary>
+        public virtual bool IsSwitchable => true;
+
         public readonly T Value;
 
         protected TabItem(T value)

osu.Framework/Input/PlatformActionContainer.cs

@@ -54,7 +54,9 @@ public enum PlatformActionType
         WordPrevious,
         WordNext,
         LineStart,
-        LineEnd
+        LineEnd,
+        DocumentPrevious,
+        DocumentNext
     }
 
     public enum PlatformActionMethod

osu.Framework/Platform/GameHost.cs

@@ -697,6 +697,10 @@ public void Dispose()
             new KeyBinding(InputKey.End, new PlatformAction(PlatformActionType.LineEnd, PlatformActionMethod.Move)),
             new KeyBinding(new KeyCombination(new[] { InputKey.Shift, InputKey.Home }), new PlatformAction(PlatformActionType.LineStart, PlatformActionMethod.Select)),
             new KeyBinding(new KeyCombination(new[] { InputKey.Shift, InputKey.End }), new PlatformAction(PlatformActionType.LineEnd, PlatformActionMethod.Select)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Control, InputKey.PageUp }), new PlatformAction(PlatformActionType.DocumentPrevious)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Control, InputKey.PageDown }), new PlatformAction(PlatformActionType.DocumentNext)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Control, InputKey.Tab }), new PlatformAction(PlatformActionType.DocumentNext)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Control, InputKey.Shift, InputKey.Tab }), new PlatformAction(PlatformActionType.DocumentPrevious)),
         };
     }
 

osu.Framework/Platform/MacOS/MacOSGameHost.cs

@@ -50,6 +50,10 @@ internal MacOSGameHost(string gameName, bool bindIPC = false)
             new KeyBinding(new KeyCombination(new[] { InputKey.Super, InputKey.Delete }), new PlatformAction(PlatformActionType.LineEnd, PlatformActionMethod.Delete)),
             new KeyBinding(new KeyCombination(new[] { InputKey.Super, InputKey.Shift, InputKey.Left }), new PlatformAction(PlatformActionType.LineStart, PlatformActionMethod.Select)),
             new KeyBinding(new KeyCombination(new[] { InputKey.Super, InputKey.Shift, InputKey.Right }), new PlatformAction(PlatformActionType.LineEnd, PlatformActionMethod.Select)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Alt, InputKey.Super, InputKey.Left }), new PlatformAction(PlatformActionType.DocumentPrevious)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Alt, InputKey.Super, InputKey.Right }), new PlatformAction(PlatformActionType.DocumentNext)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Control, InputKey.Tab }), new PlatformAction(PlatformActionType.DocumentNext)),
+            new KeyBinding(new KeyCombination(new[] { InputKey.Control, InputKey.Shift, InputKey.Tab }), new PlatformAction(PlatformActionType.DocumentPrevious)),
         };
     }
 }