Add MenuSystem which is capable of handling to focus between multiple MenuStacks, so that a closed stack can give focus back to the next most important stack automatically

Source/StevesUEHelpers/Private/StevesGameSubsystem.cpp

@@ -87,6 +87,11 @@ void UStevesGameSubsystem::OnInputDetectorModeChanged(int PlayerIndex, EInputMod
     OnInputModeChanged.Broadcast(PlayerIndex, NewMode);
 }
 
+FMenuSystem* UStevesGameSubsystem::GetMenuSystem()
+{
+    return &MenuSystem;
+}
+
 UStevesGameSubsystem::FInputModeDetector::FInputModeDetector()
 {
     // 4 local players should be plenty usually (will expand if necessary)

Source/StevesUEHelpers/Private/StevesUI/MenuBase.cpp

@@ -131,12 +131,17 @@ void UMenuBase::Open(bool bIsRegain)
         break;
     }    
 
+    TakeFocusIfDesired();
+    
+}
+
+void UMenuBase::TakeFocusIfDesired()
+{
     auto GS = GetStevesGameSubsystem(GetWorld());
     if (bRequestFocus &&
         GS && (GS->GetLastInputModeUsed() != EInputMode::Gamepad || GS->GetLastInputModeUsed() != EInputMode::Keyboard))
     {
         SetFocusProperly();
-    }
-
-    
+    }    
 }
+

Source/StevesUEHelpers/Private/StevesUI/MenuStack.cpp

@@ -4,7 +4,6 @@
 #include "StevesGameSubsystem.h"
 #include "StevesUEHelpers.h"
 #include "StevesUI/MenuBase.h"
-#include "Framework/Application/SlateApplication.h"
 #include "Kismet/GameplayStatics.h"
 
 
@@ -180,6 +179,9 @@ void UMenuStack::PushMenuByObject(UMenuBase* NewMenu)
     }
     Menus.Add(NewMenu);
     NewMenu->AddedToStack(this);
+
+    if (Menus.Num() == 1)
+        FirstMenuOpened();
 }
 
 void UMenuStack::PopMenu(bool bWasCancel)
@@ -217,9 +219,28 @@ void UMenuStack::PopMenuIfTop(UMenuBase* UiMenuBase, bool bWasCancel)
     }
 }
 
+
+void UMenuStack::FirstMenuOpened()
+{
+    // tell menu system
+    auto GS = GetStevesGameSubsystem(GetWorld());
+    GS->GetMenuSystem()->MenuStackOpened(this);       
+}
+
+void UMenuStack::RemoveFromParent()
+{
+    Super::RemoveFromParent();
+
+    // tell menu system if we're in-game (this gets called in editor too)
+    auto GS = GetStevesGameSubsystem(GetWorld());
+    if (GS)
+        GS->GetMenuSystem()->MenuStackClosed(this);
+    
+}
+
 void UMenuStack::LastMenuClosed(bool bWasCancel)
 {
-    RemoveFromParent();
+    RemoveFromParent(); // this will do MenuSystem interaction
     OnClosed.Broadcast(this, bWasCancel);
 
     ApplyInputModeChange(InputModeSettingOnClose);
@@ -228,6 +249,7 @@ void UMenuStack::LastMenuClosed(bool bWasCancel)
     
 }
 
+
 void UMenuStack::CloseAll(bool bWasCancel)
 {
     // We don't go through normal pop sequence, this is a shot circuit
@@ -239,6 +261,19 @@ void UMenuStack::CloseAll(bool bWasCancel)
     LastMenuClosed(bWasCancel);
 }
 
+bool UMenuStack::IsRequestingFocus() const
+{
+    return Menus.Num() > 0 && Menus.Last()->IsRequestingFocus();
+}
+
+void UMenuStack::TakeFocusIfDesired()
+{
+    if (IsRequestingFocus())
+    {
+        Menus.Last()->TakeFocusIfDesired();
+    }
+}
+
 void UMenuStack::SetFocusProperly_Implementation()
 {
     // Delegate to top menu

Source/StevesUEHelpers/Public/StevesGameSubsystem.h

@@ -5,6 +5,7 @@
 #include "InputCoreTypes.h"
 #include "Framework/Application/IInputProcessor.h"
 #include "StevesHelperCommon.h"
+#include "StevesUI/MenuSystem.h"
 #include "StevesUI/UiTheme.h"
 
 #include "StevesGameSubsystem.generated.h"
@@ -91,6 +92,7 @@ protected:
 
 protected:
     TSharedPtr<FInputModeDetector> InputDetector;
+    FMenuSystem MenuSystem;
 
     UPROPERTY(BlueprintReadWrite)
     UUiTheme* DefaultUiTheme;
@@ -120,4 +122,7 @@ public:
 
     /// Changes the default theme to a different one
     void SetDefaultUiTheme(UUiTheme* NewTheme) { DefaultUiTheme = NewTheme; }
+
+    /// Get the global menu system
+    FMenuSystem* GetMenuSystem();
 };

Source/StevesUEHelpers/Public/StevesUI/MenuBase.h

@@ -76,7 +76,13 @@ public:
     UFUNCTION(BlueprintCallable)
     void Close(bool bWasCancel);
 
-    TWeakObjectPtr<UMenuStack> GetParentStack() const { return ParentStack; };
+    /// Triggers this menu to take focus if appropriate
+    /// This means if the menu both requests focus, and gamepad or keyboard is in use
+    UFUNCTION(BlueprintCallable)
+    void TakeFocusIfDesired();
+
+    TWeakObjectPtr<UMenuStack> GetParentStack() const { return ParentStack; }
+    bool IsRequestingFocus() const { return bRequestFocus; }
 
     void AddedToStack(UMenuStack* Parent);
     void RemovedFromStack(UMenuStack* Parent);

Source/StevesUEHelpers/Public/StevesUI/MenuStack.h

@@ -16,7 +16,11 @@ class UMenuBase;
 DECLARE_DYNAMIC_MULTICAST_DELEGATE_TwoParams(FOnMenuStackClosed, class UMenuStack*, Stack, bool, bWasCancel);
 
 /// Represents a modal stack of menus which take focus and have a concept of "Back"
-/// Each level is a MenuBase
+/// Each level within is a MenuBase, which must be "pushed" on to the stack.
+/// Contained within MenuSystem (multiple menu stacks supported)
+/// Has a Priority so that when multiple menu stacks are open, higher priority gets focus,
+/// and when closed, next highest priority gets focus back. Focus is given when the first MenuBase is pushed onto the stack,
+/// and given up when the last one is popped.
 /// You can style this widget to be the general surrounds in which all MenuBase levels live inside
 /// Create a Blueprint subclass of this and make sure you include a UContentWidget with the name
 /// "MenuContainer" somewhere in the tree, which is where the menu contents will be placed. 
@@ -33,6 +37,7 @@ protected:
     
     TArray<UMenuBase*> Menus;
 
+    virtual void FirstMenuOpened();
     virtual void LastMenuClosed(bool bWasCancel);
 
     virtual void NativeConstruct() override;
@@ -48,6 +53,12 @@ protected:
     void InputModeChanged(int PlayerIndex, EInputMode NewMode);
 
 public:
+    /// The focus priority of this stack compared to others. When a MenuStack is opened, if it has higher priority than
+    /// any existing MenuStack open, it will be given focus. When a MenuStack with focus is closed, the next highest
+    /// priority one will be given focus. 
+    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category="Behaviour")
+    int FocusPriority = 0;
+
     /// This property will bind to a blueprint variable of the same name to contain the actual menu content
     /// If not set, or the UiMenuBase is set to not use this container, levels are added independently to viewport
     /// Use a NamedSlot for this most of the time, it gives you the most layout flexibility.
@@ -107,7 +118,16 @@ public:
     UFUNCTION(BlueprintCallable)
     void CloseAll(bool bWasCancel);
 
-
+    /// Whether the top MenuBase on this stack is requesting focus
+    UFUNCTION(BlueprintCallable)
+    bool IsRequestingFocus() const;
+    
+    /// Triggers this stack to take focus (specifically its topmost MenuBase) if appropriate
+    /// This means if both top menu on the stack requests focus, and gamepad or keyboard is in use
+    UFUNCTION(BlueprintCallable)
+    void TakeFocusIfDesired();
+    
     virtual void SetFocusProperly_Implementation() override;
-    void PopMenuIfTop(UMenuBase* UiMenuBase, bool bWasCancel);
+    virtual void PopMenuIfTop(UMenuBase* UiMenuBase, bool bWasCancel);
+    virtual void RemoveFromParent() override;
 };