Working on new root canvas stuff

Source/Integration/RootCanvas.h

@@ -0,0 +1,136 @@
+////////////////////////////////////////////////////////////
+//
+// RootCanvas.h
+//
+// UlxRootCanvasPanel is a UCanvasPanel subclass whose
+// slots (UlxRootCanvasSlot) carry input-mode configuration
+// in addition to layout. The PlayerController scans these
+// slots, sorted by ZOrder, to arbitrate pointer visibility,
+// capture, focus, and input-component blocking for
+// top-level widgets. ZOrder therefore serves double duty:
+// it determines draw order AND input priority.
+//
+////////////////////////////////////////////////////////////
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "Common.h"
+#include "Blueprint/UserWidget.h"
+#include "Components/CanvasPanel.h"
+#include "Components/CanvasPanelSlot.h"
+#include "RootCanvas.generated.h"
+
+class UWidget;
+
+
+
+////////////////////////////////////////////////////////////
+//
+// UlxRootCanvasSlot
+//
+// Luprex provides a "window management system" for root widgets.
+// This system is documented in Docs/Keyboard-Focus-and-Input-Modes.md
+// The Root Canvas Slot is how widgets ask the window management system
+// to engage certain behaviors.
+//
+////////////////////////////////////////////////////////////
+UCLASS()
+class INTEGRATION_API UlxRootCanvasSlot : public UCanvasPanelSlot
+{
+	GENERATED_BODY()
+
+public:
+
+	UlxRootCanvasSlot(const FObjectInitializer& ObjectInitializer);
+
+	// When this window is in front, the mouse pointer is shown and the
+	// viewport does not capture the mouse.
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Luprex|Input Mode")
+	bool ShowPointer = false;
+
+	// When this window is in front, this window's input component blocks
+	// lower-priority input components in the input stack.
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Luprex|Input Mode")
+	bool BlockInput = false;
+
+	// If true, this widget's input component is enabled, which is to say,
+	// that enhanced input events are enabled.  If false, enhanced input
+	// events in the Event Graph are deactivated.
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Luprex|Input Mode")
+	bool EnableEnhancedInput = true;
+};
+
+////////////////////////////////////////////////////////////
+//
+// UlxRootCanvasPanel
+//
+// A UCanvasPanel that uses UlxRootCanvasSlot for its
+// children instead of the plain UCanvasPanelSlot. Layout
+// behavior is identical to UCanvasPanel; only the slot
+// type differs.
+//
+////////////////////////////////////////////////////////////
+UCLASS()
+class INTEGRATION_API UlxRootCanvasPanel : public UCanvasPanel
+{
+	GENERATED_BODY()
+
+public:
+
+	// Convenience wrapper around AddChild that returns the
+	// derived slot type, so callers don't have to cast.
+	UFUNCTION()
+	UlxRootCanvasSlot* AddChildToRootCanvas(UWidget* Content);
+
+	// Find children of type UserWidget.  Return them in a sorted
+	// order, with the highest Zorder first.
+	TArray<UlxRootCanvasSlot*> GetSortedUserWidgets();
+
+	// Return the largest ZOrder across all slots, or 0 if empty.
+	// Used as the basis for placing new widgets on top.
+	int32 GetMaxZOrder() const;
+
+	// This function updates several window-management-related properties
+	// which are stored in the UserWidget and the lxRootCanvasSlot.  Note that
+	// it is perfectly legal to edit these properties by other means: this
+	// function is one of many valid setters.  See the documentation in
+	// Docs/Keyboard-Focus-and-Input-Modes.md for information about how Luprex
+	// window management works.
+	UFUNCTION(BlueprintCallable, Category = "Luprex|Window Management",
+		meta = (DefaultToSelf = "Widget", EnableEnhancedInput = "true"))
+	static void SetWidgetWindowManagement(class UUserWidget *Widget,
+		bool ShowPointer, bool BlockInput, bool EnableEnhancedInput,
+		bool BringToFront, UWidget *DesiredFocusWidget);
+
+	// Fetch the UlxRootCanvasSlot for a widget that is parented to a
+	// UlxRootCanvasPanel. Returns nullptr via the WrongType exec pin
+	// if the widget isn't a root widget (no slot, or slot is not a
+	// UlxRootCanvasSlot).
+	UFUNCTION(BlueprintCallable, Category = "Luprex|Window Management",
+		meta = (DefaultToSelf = "Widget", ExpandEnumAsExecs = "Result"))
+	static UlxRootCanvasSlot *GetRootCanvasSlot(class UUserWidget *Widget, ElxSuccessOrWrongType &Result);
+
+protected:
+
+	// UPanelWidget
+	virtual UClass* GetSlotClass() const override;
+};
+
+
+
+////////////////////////////////////////////////////////////
+//
+// UlxRootWidget
+//
+// A trivial concrete UUserWidget subclass used by the
+// PlayerController to host the root UlxRootCanvasPanel.
+// UUserWidget itself is marked Abstract in UMG, so we need
+// a non-abstract class to instantiate.
+//
+////////////////////////////////////////////////////////////
+UCLASS()
+class INTEGRATION_API UlxRootWidget : public UUserWidget
+{
+	GENERATED_BODY()
+};