Use placeholders to resolve the problem that an empty slot cannot be selected in the shortcut bar.

使用占位符来解决快捷栏无法选中空槽位的问题。

scripts/inventory/HotBar.cs

@@ -15,7 +15,11 @@ public partial class HotBar : HBoxContainer
     public override void _Ready()
     {
         base._Ready();
-        _itemContainer = new UniversalItemContainer(Config.HotBarSize);
+        var universalItemContainer = new UniversalItemContainer(Config.HotBarSize)
+        {
+            EnablePlaceholder = true
+        };
+        _itemContainer = universalItemContainer;
         _itemContainer.SupportSelect = true;
         _itemContainerDisplay = new ItemSlotContainerDisplay(this);
         _itemContainerDisplay.BindItemContainer(_itemContainer);

scripts/inventory/IItemContainer.cs

@@ -47,6 +47,12 @@ public interface IItemContainer : IEnumerable<IItem>
     /// </summary>
     public bool SupportSelect { get; set; }
 
+    /// <summary>
+    /// <para>Gets a placeholder object</para>
+    /// <para>获取占位符对象</para>
+    /// </summary>
+    /// <returns></returns>
+    IItem? GetPlaceHolderItem();
 
     /// <summary>
     /// <para>Gets the selected location</para>

scripts/inventory/ItemContainerDisplayTemplate.cs

@@ -1,6 +1,5 @@
 using System.Collections;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 using ColdMint.scripts.map.events;
 
 namespace ColdMint.scripts.inventory;
@@ -105,7 +104,21 @@ public abstract class ItemContainerDisplayTemplate : IItemContainerDisplay
         for (var i = startIndex; i < endIndex; i++)
         {
             var itemDisplay = ItemDisplayList[i];
-            itemDisplay.Update(i < usedCapacity ? itemContainer.GetItem(i) : null);
+            if (i < usedCapacity)
+            {
+                itemDisplay.Update(itemContainer.GetItem(i));
+            }
+            else
+            {
+                var placeHolderItem = itemContainer.GetPlaceHolderItem();
+                if (placeHolderItem != null)
+                {
+                    placeHolderItem.IsSelect = i == itemContainer.GetSelectIndex();
+                }
+
+                itemDisplay.Update(placeHolderItem);
+            }
+
             itemDisplay.ShowSelf();
         }
     }
@@ -120,7 +133,20 @@ public abstract class ItemContainerDisplayTemplate : IItemContainerDisplay
     private void UpdateDataForSingleLocation(IItemContainer itemContainer, int index, int usedCapacity)
     {
         var itemDisplay = ItemDisplayList[index];
-        itemDisplay.Update(index < usedCapacity ? itemContainer.GetItem(index) : null);
+        if (index < usedCapacity)
+        {
+            itemDisplay.Update(itemContainer.GetItem(index));
+        }
+        else
+        {
+            var placeHolderItem = itemContainer.GetPlaceHolderItem();
+            if (placeHolderItem != null)
+            {
+                placeHolderItem.IsSelect = index == itemContainer.GetSelectIndex();
+            }
+
+            itemDisplay.Update(placeHolderItem);
+        }
     }
 
     /// <summary>

scripts/inventory/Packsack.cs

@@ -1,4 +1,4 @@
-using ColdMint.scripts.pickable;
+using ColdMint.scripts.pickable;
 using ColdMint.scripts.utils;
 using Godot;
 using PacksackUi = ColdMint.scripts.loader.uiLoader.PacksackUi;

scripts/inventory/PlaceholderItem.cs

@@ -3,8 +3,8 @@ using Godot;
 namespace ColdMint.scripts.inventory;
 
 /// <summary>
-/// <para>A blank item used to occupy a space in the display. The IsSelect property is set to true so that the item display always appears selected when drawn.</para>
+/// <para>PlaceholderItem</para>
-/// <para>物品容器显示器内用于占位的空白物品。IsSelect属性设置为true，使得物品显示器绘制时总是显示为选中状态。</para>
+/// <para>占位物品</para>
 /// </summary>
 public class PlaceholderItem : IItem
 {
@@ -14,7 +14,7 @@ public class PlaceholderItem : IItem
     public string? Description { get; } = null;
     public int Quantity { get; set; } = 1;
     public int MaxQuantity { get; } = 1;
-    public bool IsSelect { get; set; } = true;
+    public bool IsSelect { get; set; }
 
     public int MergeableItemCount(IItem other, int unallocatedQuantity)
     {

scripts/inventory/UniversalItemContainer.cs

@@ -43,7 +43,7 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
     {
         //If the capacity is not full, directly return to add items
         //如果未占满容量，直接返回可添加物品
-        if (GetUsedCapacity() < GetTotalCapacity())
+        if (GetUsedCapacity() < totalCapacity)
         {
             return true;
         }
@@ -76,12 +76,16 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
         return unallocatedQuantity < 1;
     }
 
+    private void UpdateSelectStatus(int index, IItem item)
+    {
+        item.IsSelect = index == _selectIndex;
+    }
 
     public int AddItem(IItem item)
     {
         if (item.MaxQuantity == 1)
         {
-            if (GetUsedCapacity() >= GetTotalCapacity())
+            if (GetUsedCapacity() >= totalCapacity)
             {
                 //Items cannot be stacked and cannot be added if the capacity is full.
                 //物品不能叠加，且容量已满，则无法添加。
@@ -89,6 +93,7 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
             }
 
             _itemList.Add(item);
+            UpdateSelectStatus(_itemList.Count - 1, item);
             ItemDataChangeEvent?.Invoke(new ItemDataChangeEvent
             {
                 NewItem = item,
@@ -130,7 +135,7 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
 
         //New items have some left over.
         //新物品有一些剩余。
-        if (GetUsedCapacity() >= GetTotalCapacity())
+        if (GetUsedCapacity() >= totalCapacity)
         {
             //The capacity is full. The remaining capacity cannot be stored.
             //容量已满，无法存放剩余。
@@ -140,6 +145,7 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
         //Add the rest to the container.
         //添加剩余到容器内。
         _itemList.Add(item);
+        UpdateSelectStatus(_itemList.Count - 1, item);
         ItemDataChangeEvent?.Invoke(new ItemDataChangeEvent
         {
             NewItem = item,
@@ -150,6 +156,12 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
     }
 
     public bool SupportSelect { get; set; }
+    public bool EnablePlaceholder { get; set; }
+
+    public IItem? GetPlaceHolderItem()
+    {
+        return EnablePlaceholder ? new PlaceholderItem() : null;
+    }
 
     public int GetSelectIndex()
     {
@@ -158,7 +170,12 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
 
     public IItem? GetSelectItem()
     {
-        return _itemList.Count == 0 ? null : _itemList[_selectIndex];
+        if (_itemList.Count == 0)
+        {
+            return null;
+        }
+
+        return _selectIndex < _itemList.Count ? _itemList[_selectIndex] : null;
     }
 
     public IItem? GetItem(int index)
@@ -247,7 +264,7 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
 
     public void SelectNextItem()
     {
-        var count = _itemList.Count;
+        var count = EnablePlaceholder ? totalCapacity : _itemList.Count;
         if (count == 0)
         {
             return;
@@ -257,7 +274,7 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
         var newSelectIndex = _selectIndex + 1;
         if (newSelectIndex >= count)
         {
-            newSelectIndex = count - 1;
+            newSelectIndex = 0;
         }
 
         PrivateSelectItem(oldSelectIndex, newSelectIndex);
@@ -265,7 +282,7 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
 
     public void SelectPreviousItem()
     {
-        var count = _itemList.Count;
+        var count = EnablePlaceholder ? totalCapacity : _itemList.Count;
         if (count == 0)
         {
             return;
@@ -294,10 +311,23 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
             return;
         }
 
-        var oldItem = _itemList[oldIndex];
+        //There is no need to broadcast placeholders when an event is invoked.
+        //在调用事件时，无需广播占位符。
+        var oldItem = GetItem(oldIndex);
+        if (oldItem != null)
+        {
             oldItem.IsSelect = false;
-        var newItem = _itemList[newIndex];
+        }
+
+        //There is no need to broadcast placeholders when an event is invoked.
+        //在调用事件时，无需广播占位符。
+        var newItem = GetItem(newIndex);
+        if (newItem != null)
+        {
             newItem.IsSelect = true;
+        }
+
+        _selectIndex = newIndex;
         SelectedItemChangeEvent?.Invoke(new SelectedItemChangeEvent
         {
             NewIndex = newIndex,
@@ -305,11 +335,20 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
             NewItem = newItem,
             OldItem = oldItem
         });
-        _selectIndex = newIndex;
     }
 
 
     public void SelectItem(int index)
+    {
+        if (EnablePlaceholder)
+        {
+            if (totalCapacity == 0)
+            {
+                return;
+            }
+            PrivateSelectItem(_selectIndex, index % totalCapacity);
+        }
+        else
         {
             var safeIndex = GetSafeIndex(index);
             if (safeIndex == UnknownIndex)
@@ -319,4 +358,5 @@ public class UniversalItemContainer(int totalCapacity) : IItemContainer
 
             PrivateSelectItem(_selectIndex, safeIndex);
         }
+    }
 }