integration/Source/Integration/RootCanvas.h

////////////////////////////////////////////////////////////
//
// 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;

	// Knowing whether the slot is under construction helps us to work
	// around some bugs in Unreal.  See below.
	bool SlotUnderConstruction = true;
	
	// Reliable version of SetZOrder.  There is a bug in the normal version of
	// SetZOrder: it crashes if you use it during OnConstruct.  We have a
	// workaround, but it requires using a different getter and setter.
	UFUNCTION(BlueprintCallable, Category = "Luprex|Input Mode")
	void SetZOrderReliable(int32 Order);

	// Reliable version of GetZOrder.  There is a bug in the normal version of
	// SetZOrder: it crashes if you use it during OnConstruct.  We have a
	// workaround, but it requires using a different getter and setter.
	UFUNCTION(BlueprintCallable, Category = "Luprex|Input Mode")
	int32 GetZOrderReliable();
};

////////////////////////////////////////////////////////////
//
// 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()
};