GenericInputDeviceMap.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Map.h"
#include "GenericPlatform/GenericPlatformInputDeviceMapper.h"
#include "Misc/CoreMiscDefines.h"   // For FInputDeviceId/FPlatformUserId
 
template <class TDeviceKeyType>
class TInputDeviceMap
{
public: 
 
    TInputDeviceMap() = default;
    ~TInputDeviceMap() = default;
 
    [[nodiscard]] FInputDeviceId GetOrCreateDeviceId(const TDeviceKeyType& DeviceKey)
    {
        FInputDeviceId OutDeviceId = INPUTDEVICEID_NONE;
        
        // If we already know about this device, then we can just use that info
        if (FInputDeviceId* ExistingDeviceId = MappedDeviceIds.Find(DeviceKey))
        {
            OutDeviceId = *ExistingDeviceId;
        }
        // Otherwise, we have not seen this input device before (its a new connection)
        // So we need a new FInputDeviceId and a FPlatformUserId to map it to. 
        else
        {
            OutDeviceId = IPlatformInputDeviceMapper::Get().AllocateNewInputDeviceId();
 
            // Keep track of both the FInputDeviceId -> DeviceKey 
            // and DeviceKey -> FInputDeviceID for quick lookup
            MappedDeviceIds.Add(DeviceKey, OutDeviceId);
            MappedIdToKey.Add(OutDeviceId, DeviceKey);
        }
 
        return OutDeviceId;
    }
 
    [[nodiscard]] FInputDeviceId MapDefaultInputDevice(const TDeviceKeyType& DeviceKey)
    {
        FInputDeviceId OutDeviceId = IPlatformInputDeviceMapper::Get().GetDefaultInputDevice();
 
        MappedDeviceIds.Add(DeviceKey, OutDeviceId);
        MappedIdToKey.Add(OutDeviceId, DeviceKey);
 
        return OutDeviceId;
    }
 
    [[nodiscard]] FInputDeviceId FindDeviceId(const TDeviceKeyType& DeviceKey) const
    {
        FInputDeviceId OutDeviceId = INPUTDEVICEID_NONE;
 
        // If we already know about this device, then we can just use that info
        if (const FInputDeviceId* ExistingDeviceId = MappedDeviceIds.Find(DeviceKey))
        {
            OutDeviceId = *ExistingDeviceId;
        }
 
        return OutDeviceId;
    }
 
    [[nodiscard]] FInputDeviceId FindDeviceIdChecked(const TDeviceKeyType& DeviceKey) const
    {
        return MappedDeviceIds.FindChecked(DeviceKey);
    }
 
    [[nodiscard]] const TDeviceKeyType& GetDeviceKeyChecked(const FInputDeviceId DeviceId) const
    {
        return MappedIdToKey.FindChecked(DeviceId);
    }
 
    [[nodiscard]] const TDeviceKeyType* FindDeviceKey(const FInputDeviceId DeviceId) const
    {
        return MappedIdToKey.Find(DeviceId);
    }
 
protected:
 
    TMap<TDeviceKeyType, FInputDeviceId> MappedDeviceIds;
 
    TMap<FInputDeviceId, TDeviceKeyType> MappedIdToKey;
};