Highlighting inventory slots when moving items around, red highlight if an item can't be placed in a slot

Subsurface/Source/GUI/GUI.cs

@@ -264,10 +264,11 @@ namespace Barotrauma
             }
             else
             {
-                sb.Draw(t, new Rectangle(rect.X, rect.Y, rect.Width, thickness), null, clr, 0.0f, Vector2.Zero, SpriteEffects.None, depth);
+                sb.Draw(t, new Rectangle(rect.X + thickness, rect.Y, rect.Width - thickness * 2, thickness), null, clr, 0.0f, Vector2.Zero, SpriteEffects.None, depth);
-                sb.Draw(t, new Rectangle(rect.X, rect.Y+rect.Height- thickness, rect.Width, thickness), null, clr, 0.0f, Vector2.Zero, SpriteEffects.None, depth);
+                sb.Draw(t, new Rectangle(rect.X + thickness, rect.Y + rect.Height - thickness, rect.Width - thickness * 2, thickness), null, clr, 0.0f, Vector2.Zero, SpriteEffects.None, depth);
+
                 sb.Draw(t, new Rectangle(rect.X, rect.Y, thickness, rect.Height), null, clr, 0.0f, Vector2.Zero, SpriteEffects.None, depth);
-                sb.Draw(t, new Rectangle(rect.X+rect.Width- thickness, rect.Y, thickness, rect.Height), null, clr, 0.0f, Vector2.Zero, SpriteEffects.None, depth);
+                sb.Draw(t, new Rectangle(rect.X + rect.Width - thickness, rect.Y, thickness, rect.Height), null, clr, 0.0f, Vector2.Zero, SpriteEffects.None, depth);
             }
         }
 

Subsurface/Source/Items/CharacterInventory.cs

@@ -169,7 +169,7 @@ namespace Barotrauma
                     if (allowedSlot.HasFlag(limbSlots[i]) && Items[i]!=null && Items[i]!=item)
                     {
                         free = false;
-                        break;
+                        if (slots != null) slots[i].ShowBorderHighlight(Color.Red, 0.1f, 0.9f);
                     }
                 }
 
@@ -239,7 +239,6 @@ namespace Barotrauma
                         TryPutItem(item, currentIndex, false, false);
                         TryPutItem(existingItem, index, false, false);
                     }                    
-                    
                 }
                 
                 return combined;
@@ -293,17 +292,19 @@ namespace Barotrauma
 
         protected override void CreateSlots()
         {
-            slots = new InventorySlot[capacity];
+            if (slots == null) slots = new InventorySlot[capacity];
 
             int rectWidth = 40, rectHeight = 40;
             
             Rectangle slotRect = new Rectangle(0, 0, rectWidth, rectHeight);
             for (int i = 0; i < capacity; i++)
             {
+                slots[i].Disabled = false;
+
                 slotRect.X = (int)(SlotPositions[i].X + DrawOffset.X);
                 slotRect.Y = (int)(SlotPositions[i].Y + DrawOffset.Y);
 
-                slots[i] = new InventorySlot(slotRect);
+                slots[i].Rect = slotRect;
 
                 slots[i].Color = limbSlots[i] == InvSlotType.Any ? Color.White * 0.2f : Color.White * 0.4f;
             }

Subsurface/Source/Items/Inventory.cs

@@ -28,6 +28,9 @@ namespace Barotrauma
 
         public Color Color;
 
+        public Color BorderHighlightColor;
+        private CoroutineHandle BorderHighlightCoroutine;
+
         public InventorySlot(Rectangle rect)
         {
             Rect = rect;
@@ -36,6 +39,33 @@ namespace Barotrauma
 
             Color = Color.White * 0.4f;
         }
+
+        public void ShowBorderHighlight(Color color, float fadeInDuration, float fadeOutDuration)
+        {
+            if (BorderHighlightCoroutine != null)
+            {
+                BorderHighlightCoroutine = null;
+            }
+
+            BorderHighlightCoroutine = CoroutineManager.StartCoroutine(UpdateBorderHighlight(color, fadeInDuration, fadeOutDuration));
+        }
+
+        private IEnumerable<object> UpdateBorderHighlight(Color color, float fadeInDuration, float fadeOutDuration)
+        {
+            float t = 0.0f;
+            while (t < fadeInDuration + fadeOutDuration)
+            {
+                BorderHighlightColor = (t < fadeInDuration) ?
+                    Color.Lerp(Color.Transparent, color, t / fadeInDuration) :
+                    Color.Lerp(color, Color.Transparent, (t - fadeInDuration) / fadeOutDuration);
+
+                t += CoroutineManager.DeltaTime;
+
+                yield return CoroutineStatus.Running;
+            }
+
+            yield return CoroutineStatus.Success;
+        }
     }
 
     class Inventory
@@ -163,6 +193,7 @@ namespace Barotrauma
             }
             else
             {
+                if (slots != null) slots[i].ShowBorderHighlight(Color.Red, 0.1f, 0.9f);
                 return false;
             }
         }
@@ -179,6 +210,9 @@ namespace Barotrauma
 
             Items[i] = item;
             item.ParentInventory = this;
+
+            if (slots != null) slots[i].ShowBorderHighlight(Color.White, 0.1f, 0.4f);
+
             if (item.body != null)
             {
                 item.body.Enabled = false;
@@ -323,7 +357,7 @@ namespace Barotrauma
             Vector2 rectSize = textSize * 1.2f;
 
             Vector2 pos = new Vector2(highlightedSlot.Right, highlightedSlot.Y-rectSize.Y);
-            pos.X = (int)pos.X;
+            pos.X = (int)(pos.X + 3);
             pos.Y = (int)pos.Y;
             
             GUI.DrawRectangle(spriteBatch, pos, rectSize, Color.Black * 0.8f, true);
@@ -370,10 +404,20 @@ namespace Barotrauma
                         doubleClickedItem = item;
                     }
 
-                    //selectedSlot = slotIndex;
+                    if (draggingItem != Items[slotIndex])
-                    TryPutItem(draggingItem, slotIndex, true, true);
+                    {
-                    draggingItem = null;
+                        //selectedSlot = slotIndex;
-                    draggingSlot = null;
+                        if (TryPutItem(draggingItem, slotIndex, true, true))
+                        {
+                            if (slots != null) slots[slotIndex].ShowBorderHighlight(Color.White, 0.1f, 0.4f);
+                        }
+                        else
+                        {
+                            if (slots != null) slots[slotIndex].ShowBorderHighlight(Color.Red, 0.1f, 0.9f);
+                        }
+                        draggingItem = null;
+                        draggingSlot = null;
+                    }
                 }
             }
         }
@@ -471,6 +515,14 @@ namespace Barotrauma
 
             GUI.DrawRectangle(spriteBatch, rect, (slot.IsHighlighted ? Color.Red * 0.4f : slot.Color), false);
 
+            if (slot.BorderHighlightColor != Color.Transparent)
+            {
+                Rectangle highlightRect = slot.Rect;
+                highlightRect.Inflate(3,3);
+                
+                GUI.DrawRectangle(spriteBatch, highlightRect, slot.BorderHighlightColor, false, 0, 5);
+            }
+
             if (item == null || !drawItem) return;
 
             item.Sprite.Draw(spriteBatch, new Vector2(rect.X + rect.Width / 2, rect.Y + rect.Height / 2), item.Color);