Development

core/src/main/java/me/zort/containr/Element.java

@@ -9,6 +9,8 @@
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.function.Consumer;
+
 @Getter
 public abstract class Element implements Component {
 
@@ -23,4 +25,14 @@ public void click(ContextClickInfo info) {}
     @Nullable
     public abstract ItemStack item(Player player);
 
+    /**
+     * Post-process the created ItemStack before it is applied to the GUI.
+     *
+     * @param player The player for which the item has been created.
+     * @param item The created item. Is not the same as the returned from {@link #item(Player)}.
+     * @param newItemConsumer The handler that MUST be called after the item has been modified to update the menu.
+     */
+    public void postProcessItem(Player player, ItemStack item, Consumer<ItemStack> newItemConsumer) {
+        // No modifications by default.
+    }
 }

core/src/main/java/me/zort/containr/GUI.java

@@ -217,6 +217,9 @@ public void update(@NotNull Player p, boolean clear, Class<? extends Element>...
                     item = NBT.modifyNBT(item, nbtItem -> nbtItem.setString(Constants.ELEMENT_ID_KEY, element.getId()));
                 }
                 if(slot < inventory.getSize() && slot >= 0) {
+                    Consumer<ItemStack> processFinalItem = (finalItem) -> inventory.setItem(slot, finalItem);
+                    element.postProcessItem(p, item, processFinalItem);
+
                     inventory.setItem(slot, item);
                 } else {
                     String err = "Cannot complete menu %s for player %s because index out of bounds: %d >= %d";