Add new input device processor

Source/Integration/InputDeviceTracker.h

@@ -0,0 +1,63 @@
+////////////////////////////////////////////////////////////
+//
+// InputDeviceTracker.h
+//
+// Tracks the most recently used input device, classifying
+// it as keyboard/mouse, Xbox gamepad, or PlayStation
+// gamepad. The subsystem registers a Slate input
+// preprocessor that watches button-down events; analog
+// and mouse-move events are ignored. Read the current
+// classification via the static accessor.
+//
+////////////////////////////////////////////////////////////
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "Subsystems/GameInstanceSubsystem.h"
+#include "Framework/Application/IInputProcessor.h"
+#include "Common.h"
+#include "InputDeviceTracker.generated.h"
+
+////////////////////////////////////////////////////////////
+//
+// FInputDeviceTrackerProcessor
+//
+// Slate input preprocessor. Updates the device-class
+// static on each button-down event. Never consumes
+// events (always returns false).
+//
+////////////////////////////////////////////////////////////
+
+class FInputDeviceTrackerProcessor : public IInputProcessor
+{
+public:
+	virtual void Tick(const float DeltaTime, FSlateApplication& SlateApp, TSharedRef<ICursor> Cursor) override {}
+	virtual bool HandleKeyDownEvent(FSlateApplication& SlateApp, const FKeyEvent& KeyEvent) override;
+	virtual bool HandleMouseButtonDownEvent(FSlateApplication& SlateApp, const FPointerEvent& MouseEvent) override;
+};
+
+////////////////////////////////////////////////////////////
+//
+// UlxInputDeviceTracker
+//
+////////////////////////////////////////////////////////////
+
+UCLASS(MinimalAPI)
+class UlxInputDeviceTracker : public UGameInstanceSubsystem
+{
+	GENERATED_BODY()
+
+public:
+	virtual void Initialize(FSubsystemCollectionBase& Collection) override;
+	virtual void Deinitialize() override;
+
+	// Returns the classification of the most recently used
+	// input device. Defaults to KeyboardMouse until the
+	// first gamepad button event is observed.
+	//
+	static ElxControllerType GetLastControllerType();
+
+private:
+	TSharedPtr<FInputDeviceTrackerProcessor> Processor;
+};