UFWInventoryComponent¶

Header: FWInventoryComponent.h | Parent: UActorComponent | Specifier: BlueprintSpawnableComponent

The primary inventory management component. Uses FFWItemArray (backed by FFastArraySerializer) for bandwidth-efficient delta replication. Supports adding, removing, moving, equipping, and stacking items with full Blueprint exposure.

Class Declaration¶

UCLASS(ClassGroup = (FrostWeb), meta = (BlueprintSpawnableComponent))
class FWINVENTORYSYSTEM_API UFWInventoryComponent : public UActorComponent
{
    GENERATED_BODY()

public:
    UFWInventoryComponent();

    // --- Item Operations ---
    UFUNCTION(BlueprintCallable, Category = "Inventory")
    bool AddItem(const FFWItemInstance& Item);

    UFUNCTION(BlueprintCallable, Category = "Inventory")
    bool RemoveItem(const FGuid& InstanceId, int32 Quantity = 1);

    UFUNCTION(BlueprintCallable, Category = "Inventory")
    bool MoveItem(const FGuid& InstanceId, int32 TargetSlot);

    UFUNCTION(BlueprintCallable, Category = "Inventory")
    bool EquipItem(const FGuid& InstanceId);

    UFUNCTION(BlueprintCallable, Category = "Inventory")
    bool UnequipItem(EFWEquipmentType Slot);

    // --- Queries ---
    UFUNCTION(BlueprintPure, Category = "Inventory")
    const FFWItemInstance* GetItemAt(int32 SlotIndex) const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    const FFWItemInstance* FindItemByDefinition(
        const UFWItemDefinition* Definition) const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    int32 GetItemCount(const UFWItemDefinition* Definition) const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    bool HasItem(const UFWItemDefinition* Definition,
        int32 RequiredQuantity = 1) const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    int32 GetCapacity() const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    int32 GetUsedSlots() const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    int32 GetFreeSlots() const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    bool IsFull() const;

    UFUNCTION(BlueprintPure, Category = "Inventory")
    const TArray<FFWItemInstance>& GetAllItems() const;
};

Replication¶

FFWItemArray¶

The inventory's item storage uses FFWItemArray, a custom FFastArraySerializer implementation that provides delta replication. Only changed items are replicated each network update, significantly reducing bandwidth compared to full array replication.

USTRUCT()
struct FFWItemArray : public FFastArraySerializer
{
    GENERATED_BODY()

    UPROPERTY()
    TArray<FFWItemArrayEntry> Items;

    bool NetDeltaSerialize(FNetDeltaSerializeInfo& DeltaParms);
};

Replication Requirements

For delta replication to function:

The owning actor must have bReplicates = true.
The inventory component must be added to the replicated subobject list.
The GetLifetimeReplicatedProps function must include the item array.

void UFWInventoryComponent::GetLifetimeReplicatedProps(
    TArray<FLifetimeProperty>& OutLifetimeProps) const
{
    Super::GetLifetimeReplicatedProps(OutLifetimeProps);
    DOREPLIFETIME(UFWInventoryComponent, ItemArray);
}

Functions¶

Item Operations¶

AddItem¶

UFUNCTION(BlueprintCallable, Category = "Inventory")
bool AddItem(const FFWItemInstance& Item);

Adds an item to the inventory. If the item is stackable and a matching stack exists with available capacity, the quantity is added to the existing stack. Otherwise, a new slot is used.

Parameter	Type	Description
`Item`	`FFWItemInstance`	The item instance to add.

Returns: true if the item was successfully added, false if the inventory is full.

Behavior:

If the item definition has bIsStackable = true, search for an existing stack of the same definition.
If found and the stack has room (current + new <= MaxStackSize), add to existing stack.
If no room in existing stacks or not stackable, place in the first empty slot.
If no empty slots, broadcast OnInventoryFull and return false.

RemoveItem¶

UFUNCTION(BlueprintCallable, Category = "Inventory")
bool RemoveItem(const FGuid& InstanceId, int32 Quantity = 1);

Removes a quantity of items from the inventory by instance ID.

Parameter	Type	Default	Description
`InstanceId`	`FGuid`		The unique instance identifier.
`Quantity`	`int32`	`1`	Number to remove. If this equals the stack size, the entire slot is cleared.

Returns: true if the requested quantity was removed.

MoveItem¶

UFUNCTION(BlueprintCallable, Category = "Inventory")
bool MoveItem(const FGuid& InstanceId, int32 TargetSlot);

Moves an item to a different inventory slot. If the target slot is occupied by a compatible stackable item, the items are merged. If occupied by an incompatible item, the items swap positions.

Parameter	Type	Description
`InstanceId`	`FGuid`	The instance to move.
`TargetSlot`	`int32`	Zero-based target slot index.

EquipItem¶

UFUNCTION(BlueprintCallable, Category = "Inventory")
bool EquipItem(const FGuid& InstanceId);

Equips an item from the inventory to the appropriate equipment slot. The slot is determined by the item's EFWEquipmentType. If the slot is already occupied, the equipped item is returned to the inventory.

Parameter	Type	Description
`InstanceId`	`FGuid`	The instance to equip.

Equipment Component Required

This function requires a UFWEquipmentComponent on the same actor. If not present, it logs a warning and returns false.

UnequipItem¶

UFUNCTION(BlueprintCallable, Category = "Inventory")
bool UnequipItem(EFWEquipmentType Slot);

Unequips the item in the specified equipment slot and returns it to the inventory.

Parameter	Type	Description
`Slot`	`EFWEquipmentType`	The equipment slot to clear.

Queries¶

GetItemAt¶

UFUNCTION(BlueprintPure, Category = "Inventory")
const FFWItemInstance* GetItemAt(int32 SlotIndex) const;

Returns the item at the specified slot index, or nullptr if the slot is empty.

FindItemByDefinition¶

UFUNCTION(BlueprintPure, Category = "Inventory")
const FFWItemInstance* FindItemByDefinition(
    const UFWItemDefinition* Definition) const;

Finds the first item instance matching the given definition. Returns nullptr if not found.

GetItemCount¶

UFUNCTION(BlueprintPure, Category = "Inventory")
int32 GetItemCount(const UFWItemDefinition* Definition) const;

Returns the total quantity of items matching the given definition across all stacks.

Delegates¶

UPROPERTY(BlueprintAssignable, Category = "Inventory|Events")
FOnInventoryChanged OnInventoryChanged;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Events")
FOnItemAdded OnItemAdded;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Events")
FOnItemRemoved OnItemRemoved;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Events")
FOnItemMoved OnItemMoved;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Events")
FOnItemStackChanged OnItemStackChanged;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Events")
FOnInventoryLoaded OnInventoryLoaded;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Events")
FOnInventoryFull OnInventoryFull;

// Bank delegates
UPROPERTY(BlueprintAssignable, Category = "Inventory|Bank")
FOnBankCollectionChanged OnBankCollectionChanged;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Bank")
FOnBankCustomTabChanged OnBankCustomTabChanged;

UPROPERTY(BlueprintAssignable, Category = "Inventory|Bank")
FOnBankLoaded OnBankLoaded;

See Events and Delegates for full delegate signatures.

Usage Example¶

C++Blueprint

void AMyCharacter::PickupItem(AActor* ItemActor)
{
    AWorldItem* WorldItem = Cast<AWorldItem>(ItemActor);
    if (!WorldItem) return;

    FFWItemInstance NewItem;
    NewItem.InstanceId = FGuid::NewGuid();
    NewItem.Definition = WorldItem->GetItemDefinition();
    NewItem.Quantity = WorldItem->GetQuantity();

    if (Inventory->AddItem(NewItem))
    {
        WorldItem->Destroy();
    }
    else
    {
        // Inventory full notification is handled by OnInventoryFull delegate
    }
}

Add FW Inventory Component to your character.
Create an FFWItemInstance struct with the item definition and quantity.
Call Add Item on the inventory component.
Bind On Inventory Full to show a "bags full" notification.