UIInventorySlot.cs

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using TMPro;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
 
public class UIInventorySlot : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler, IPointerEnterHandler, IPointerExitHandler, IPointerClickHandler
{
    public Image m_InventorySlotHighlight;
    public Image m_InventorySlotImage;
    public TextMeshProUGUI m_TextMeshProUGUI;
 
    [HideInInspector]
    public ItemDetails m_ItemDetails;
 
    [HideInInspector]
    public int m_ItemQuantity;
 
    [HideInInspector]
    public bool m_IsSelected = false;
 
    private Camera m_MainCamera;
    private Transform m_ParentItem;
    private GameObject m_DraggedItem;
    private GridCursor m_GridCursor;
    private Canvas m_ParentCanvas;
 
    [SerializeField]
    private UIInventoryBar m_InventoryBar;
 
    [SerializeField]
    private GameObject m_InventoryTextBoxPrefab = null;
 
    [SerializeField]
    private GameObject m_ItemPrefab = null;
 
    [SerializeField]
    private int m_SlotNumber = 0;
 
    private void Awake()
    {
        m_ParentCanvas = GetComponentInParent<Canvas>();
    }
 
    private void OnDisable()
    {
        EventHandler.AfterSceneLoadEvent -= SceneLoaded;
        EventHandler.m_DropSelectedItemEvent -= DropSelectedItemAtMousePosition;
    }
 
    private void OnEnable()
    {
        EventHandler.AfterSceneLoadEvent += SceneLoaded;
        EventHandler.m_DropSelectedItemEvent += DropSelectedItemAtMousePosition;
    }
 
    private void Start()
    {
        m_MainCamera = Camera.main;
        m_GridCursor = FindObjectOfType<GridCursor>();
    }
 
    private void ClearCursors()
    {
        // Disable cursor
        m_GridCursor.DisableCursor();
 
        // Set item type to none.
        m_GridCursor.SelectedItemType = ItemType.None;
    }
 
    private void SetSelectedItem()
    {
        // Clear currently highlighted items.
        m_InventoryBar.ClearHighlightOnInventorySlots();
 
        // Highlight item on inventory bar
        m_IsSelected = true;
 
        // Set highlighted inventory slot.
        m_InventoryBar.SetHighlightedInventorySlots();
 
        // Set use radius for cursor
        m_GridCursor.ItemUseGridRadius = m_ItemDetails.m_ItemUseGridRadius;
 
        // If item requires a grid cursor, then enable the cursor.
        if( m_ItemDetails.m_ItemUseGridRadius > 0 )
        {
            m_GridCursor.EnableCursor();
        }
        else
        {
            m_GridCursor.DisableCursor();
        }
 
        // Set item type
        m_GridCursor.SelectedItemType = m_ItemDetails.m_ItemType;
 
        // Set item selected in inventory
        InventoryManager.Instance.SetSelectedInventoryItem( InventoryLocation.Player, m_ItemDetails.m_ItemCode );
 
        if( m_ItemDetails.m_CanBeCarried == true )
        {
            // Show player carrying item
            Player.Instance.ShowCarriedItem( m_ItemDetails.m_ItemCode );
        }
        else
        {
            Player.Instance.ClearCarriedItem();
        }
    }
 
    private void ClearSelectedItem()
    {
        ClearCursors();
 
        m_InventoryBar.ClearHighlightOnInventorySlots();
 
        m_IsSelected = false;
 
        // Set no item selected in inventory
        InventoryManager.Instance.ClearSelectedInventoryItem( InventoryLocation.Player );
 
        // Clear player carrying item
        Player.Instance.ClearCarriedItem();
    }
 
    private void DropSelectedItemAtMousePosition()
    {
        if( m_ItemDetails != null && m_IsSelected )
        {  
            // Check if this is a valid cursor position or not.
            if( m_GridCursor.CursorPositionIsValid )
            {
                Vector3 worldPosiiton = m_MainCamera.ScreenToWorldPoint( new Vector3( Input.mousePosition.x, Input.mousePosition.y, -m_MainCamera.transform.position.z ) );
 
                // Create item from prefab at mouse position
                GameObject itemGameObject = Instantiate( m_ItemPrefab, new Vector3( worldPosiiton.x, ( worldPosiiton.y - Settings.m_GridCellSize / 2.0f ), worldPosiiton.z ), Quaternion.identity, m_ParentItem );
                Item item = itemGameObject.GetComponent<Item>();
                item.ItemCode = m_ItemDetails.m_ItemCode;
 
                // Remove item from player inventory.
                InventoryManager.Instance.RemoveItem( InventoryLocation.Player, item.ItemCode );
 
                // If no more of item then clear selected
                if (InventoryManager.Instance.FindItemInInventory( InventoryLocation.Player, item.ItemCode) == -1 )
                {
                    ClearSelectedItem();
                }
            }
        }
    }
 
    public void OnBeginDrag( PointerEventData eventData )
    {
        if( m_ItemDetails != null )
        {
            // Disable keyboard inputs.
            Player.Instance.DisablePlayerInputAndResetMovement();
 
            // Instantiate gameobject as dragged item
            m_DraggedItem = Instantiate( m_InventoryBar.m_InventoryBarDraggedItem, m_InventoryBar.transform );
 
            // Get Image for dragged item
            Image draggedItemImage = m_DraggedItem.GetComponentInChildren<Image>();
            draggedItemImage.sprite = m_InventorySlotImage.sprite;
 
            SetSelectedItem();
        }
    }
 
    public void OnDrag( PointerEventData eventData )
    {
        if( m_DraggedItem != null )
        {
            m_DraggedItem.transform.position = Input.mousePosition;
        }
    }
 
    public void OnEndDrag( PointerEventData eventData )
    {
        // Destroy gameobject as dragged item
        if( m_DraggedItem != null )
        {
            Destroy( m_DraggedItem );
 
            // If drag ends over inventory bar, get item drag is over and swap them
            if(  eventData.pointerCurrentRaycast.gameObject != null && eventData.pointerCurrentRaycast.gameObject.GetComponent<UIInventorySlot>() != null )
            {
                // Get the slot number when the drag ends.
                int toSlotNumber = eventData.pointerCurrentRaycast.gameObject.GetComponent<UIInventorySlot>().m_SlotNumber;
 
                // Swap inventory items in inventory list.
                InventoryManager.Instance.SwapInventoryItems( InventoryLocation.Player, m_SlotNumber, toSlotNumber );
 
                // Destroy inventory text box
                DestroyInventoryTextBox();
 
                ClearSelectedItem();
            }
            else
            {
                if( m_ItemDetails.m_CanBeDropped )
                {
                    DropSelectedItemAtMousePosition();
                }
            }
 
            // Enable player Input
            Player.Instance.EnablePlayerInput();
        }
    }
 
    public void OnPointerClick( PointerEventData eventData )
    {
        if( eventData.button == PointerEventData.InputButton.Left )
        {
            // If inventory slot currently selected then deselect
            if( m_IsSelected == true )
            {
                ClearSelectedItem();
            }
            else
            {
                if( m_ItemQuantity > 0 )
                {
                    SetSelectedItem();
                }
            }
        }
    }
 
    public void OnPointerEnter( PointerEventData eventData )
    {
        if( m_ItemQuantity != 0 )
        {
            // Instantiate inventory textbox
            m_InventoryBar.m_InventoryTextBoxGameObject = Instantiate( m_InventoryTextBoxPrefab, transform.position, Quaternion.identity );
            m_InventoryBar.m_InventoryTextBoxGameObject.transform.SetParent( m_ParentCanvas.transform, false );
 
            UIInventoryTextBox inventoryTextBox = m_InventoryBar.m_InventoryTextBoxGameObject.GetComponent<UIInventoryTextBox>();
 
            // Set item type description
            string itemTypeDescription = InventoryManager.Instance.GetItemTypeDescription( m_ItemDetails.m_ItemType );
 
            // Populate TextBox
            inventoryTextBox.SetTextBoxText( m_ItemDetails.m_ItemDescription, itemTypeDescription, "", m_ItemDetails.m_ItemLongDescription, "", "" );
 
            // Set TextBox position according to inventory bar position
            if( m_InventoryBar.IsInventoryBarPositionBottom )
            {
                m_InventoryBar.m_InventoryTextBoxGameObject.GetComponent<RectTransform>().pivot = new Vector2( 0.5f, 0f );
                m_InventoryBar.m_InventoryTextBoxGameObject.transform.position = new Vector3( transform.position.x, transform.position.y + 50f, transform.position.z );
            }
            else
            {
                m_InventoryBar.m_InventoryTextBoxGameObject.GetComponent<RectTransform>().pivot = new Vector2( 0.5f, 1f );
                m_InventoryBar.m_InventoryTextBoxGameObject.transform.position = new Vector3(transform.position.x, transform.position.y - 50f, transform.position.z);
            }
        }
    }
 
    public void OnPointerExit( PointerEventData eventData )
    {
        DestroyInventoryTextBox();
    }
 
    public void DestroyInventoryTextBox()
    {
        if( m_InventoryBar.m_InventoryTextBoxGameObject != null )
        {
            Destroy( m_InventoryBar.m_InventoryTextBoxGameObject );
        }
    }
 
    public void SceneLoaded()
    {
        m_ParentItem = GameObject.FindGameObjectWithTag( Tags.ItemsParentTransform ).transform;
    }
}