Add Support for Custom Item Settings

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/CustomItemSetting.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.item.v1;
+
+import java.util.function.Supplier;
+
+import org.jetbrains.annotations.ApiStatus;
+
+import net.minecraft.item.Item;
+
+import net.fabricmc.fabric.impl.item.FabricItemInternals;
+
+/**
+ * A type of setting that can be passed to item constructors.
+ * This feature can be used by mods to add non-standard settings
+ * to items in a way that is compatible with other mods that add
+ * settings to items.
+ *
+ * @param <T> the type of the setting to be attached
+ */
+public final class CustomItemSetting<T> {
+	private final Supplier<T> defaultValue;
+
+	private CustomItemSetting(Supplier<T> defaultValue) {
+		this.defaultValue = defaultValue;
+	}
+
+	// There are a lot of these for convenience sake.
+	public static <T> CustomItemSetting<T> of(Supplier<T> defaultValue) {
+		return new CustomItemSetting<>(defaultValue);
+	}
+
+	public static CustomItemSetting<Integer> of(int defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<Long> of(long defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<Float> of(float defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<Double> of(double defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<Boolean> of(boolean defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<Byte> of(byte defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<Short> of(short defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<Character> of(char defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	public static CustomItemSetting<String> of(String defaultValue) {
+		return new CustomItemSetting<>(() -> defaultValue);
+	}
+
+	@ApiStatus.Internal
+	public T getDefaultValue() {
+		return defaultValue.get();
+	}
+
+	/**
+	 * Returns the current value of this setting for the given {@link Item}.
+	 * Should only be called after or within item construction.
+	 *
+	 * @param item the item
+	 * @return the current setting if present, the default setting if not
+	 */
+	public T getValue(Item item) {
+		return FabricItemInternals.getSetting(item, this);
+	}
+}

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/FabricItemSettings.java

@@ -16,6 +16,11 @@
 
 package net.fabricmc.fabric.api.item.v1;
 
+import java.util.Map;
+import java.util.WeakHashMap;
+
+import org.jetbrains.annotations.ApiStatus;
+
 import net.minecraft.item.FoodComponent;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemGroup;
@@ -32,14 +37,16 @@
  * {@code new FabricItemSettings()}.
  */
 public class FabricItemSettings extends Item.Settings {
+	private final Map<CustomItemSetting<?>, Object> customSettings = new WeakHashMap<>();
+
 	/**
 	 * Sets the equipment slot provider of the item.
 	 *
 	 * @param equipmentSlotProvider the equipment slot provider
 	 * @return this builder
 	 */
 	public FabricItemSettings equipmentSlot(EquipmentSlotProvider equipmentSlotProvider) {
-		FabricItemInternals.computeExtraData(this).equipmentSlot(equipmentSlotProvider);
+		this.customSettings.put(FabricItemInternals.EQUIPMENT_SLOT_PROVIDER, equipmentSlotProvider);
 		return this;
 	}
 
@@ -49,10 +56,27 @@ public FabricItemSettings equipmentSlot(EquipmentSlotProvider equipmentSlotProvi
 	 * @see CustomDamageHandler
 	 */
 	public FabricItemSettings customDamage(CustomDamageHandler handler) {
-		FabricItemInternals.computeExtraData(this).customDamage(handler);
+		this.customSettings.put(FabricItemInternals.CUSTOM_DAMAGE_HANDLER, handler);
+		return this;
+	}
+
+	/**
+	 * Sets a custom setting of the item.
+
+	 * @param setting the unique type for this setting
+	 * @param value the object containing the setting itself
+	 * @return this builder
+	 */
+	public <T> FabricItemSettings customSetting(CustomItemSetting<T> setting, T value) {
+		this.customSettings.put(setting, value);
 		return this;
 	}
 
+	@ApiStatus.Internal
+	public Map<CustomItemSetting<?>, ?> getCustomSettings() {
+		return this.customSettings;
+	}
+
 	// Overrides of vanilla methods
 
 	@Override

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/impl/item/FabricItemInternals.java

@@ -16,42 +16,30 @@
 
 package net.fabricmc.fabric.impl.item;
 
-import java.util.WeakHashMap;
+import java.util.Map;
 
 import net.minecraft.item.Item;
 
+import net.fabricmc.fabric.api.item.v1.CustomItemSetting;
+import net.fabricmc.fabric.api.item.v1.FabricItemSettings;
 import net.fabricmc.fabric.api.item.v1.CustomDamageHandler;
 import net.fabricmc.fabric.api.item.v1.EquipmentSlotProvider;
 
 public final class FabricItemInternals {
-	private static final WeakHashMap<Item.Settings, ExtraData> extraData = new WeakHashMap<>();
+	public static final CustomItemSetting<EquipmentSlotProvider> EQUIPMENT_SLOT_PROVIDER = CustomItemSetting.of(() -> null);
+	public static final CustomItemSetting<CustomDamageHandler> CUSTOM_DAMAGE_HANDLER = CustomItemSetting.of(() -> null);
 
 	private FabricItemInternals() {
 	}
 
-	public static ExtraData computeExtraData(Item.Settings settings) {
-		return extraData.computeIfAbsent(settings, s -> new ExtraData());
+	public static <T> T getSetting(Item item, CustomItemSetting<T> setting) {
+		return ((ItemExtensions) item).fabric_getCustomItemSetting(setting);
 	}
 
-	public static void onBuild(Item.Settings settings, Item item) {
-		ExtraData data = extraData.get(settings);
-
-		if (data != null) {
-			((ItemExtensions) item).fabric_setEquipmentSlotProvider(data.equipmentSlotProvider);
-			((ItemExtensions) item).fabric_setCustomDamageHandler(data.customDamageHandler);
-		}
-	}
-
-	public static final class ExtraData {
-		private /* @Nullable */ EquipmentSlotProvider equipmentSlotProvider;
-		private /* @Nullable */ CustomDamageHandler customDamageHandler;
-
-		public void equipmentSlot(EquipmentSlotProvider equipmentSlotProvider) {
-			this.equipmentSlotProvider = equipmentSlotProvider;
-		}
-
-		public void customDamage(CustomDamageHandler handler) {
-			this.customDamageHandler = handler;
+	public static void onBuild(Item.Settings settings, ItemExtensions item) {
+		if (settings instanceof FabricItemSettings) {
+			Map<CustomItemSetting<?>, Object> customItemSettings = item.fabric_getCustomItemSettings();
+			customItemSettings.putAll(((FabricItemSettings) settings).getCustomSettings());
 		}
 	}
 }

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/impl/item/ItemExtensions.java

@@ -16,12 +16,13 @@
 
 package net.fabricmc.fabric.impl.item;
 
-import net.fabricmc.fabric.api.item.v1.CustomDamageHandler;
-import net.fabricmc.fabric.api.item.v1.EquipmentSlotProvider;
+import java.util.Map;
+
+import org.jetbrains.annotations.NotNull;
+
+import net.fabricmc.fabric.api.item.v1.CustomItemSetting;
 
 public interface ItemExtensions {
-	/* @Nullable */ EquipmentSlotProvider fabric_getEquipmentSlotProvider();
-	void fabric_setEquipmentSlotProvider(EquipmentSlotProvider equipmentSlotProvider);
-	/* @Nullable */ CustomDamageHandler fabric_getCustomDamageHandler();
-	void fabric_setCustomDamageHandler(CustomDamageHandler handler);
+	@NotNull Map<CustomItemSetting<?>, Object> fabric_getCustomItemSettings();
+	<T> T fabric_getCustomItemSetting(CustomItemSetting<T> type);
 }

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/ItemMixin.java

@@ -16,6 +16,10 @@
 
 package net.fabricmc.fabric.mixin.item;
 
+import java.util.HashMap;
+import java.util.Map;
+
+import org.jetbrains.annotations.NotNull;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Unique;
 import org.spongepowered.asm.mixin.injection.At;
@@ -24,41 +28,28 @@
 
 import net.minecraft.item.Item;
 
-import net.fabricmc.fabric.api.item.v1.CustomDamageHandler;
-import net.fabricmc.fabric.api.item.v1.EquipmentSlotProvider;
 import net.fabricmc.fabric.impl.item.FabricItemInternals;
 import net.fabricmc.fabric.impl.item.ItemExtensions;
+import net.fabricmc.fabric.api.item.v1.CustomItemSetting;
 
 @Mixin(Item.class)
-abstract class ItemMixin implements ItemExtensions {
-	@Unique
-	private EquipmentSlotProvider equipmentSlotProvider;
-
+class ItemMixin implements ItemExtensions {
 	@Unique
-	private CustomDamageHandler customDamageHandler;
+	private final HashMap<CustomItemSetting<?>, Object> customItemSettings = new HashMap<>();
 
 	@Inject(method = "<init>", at = @At("RETURN"))
 	private void onConstruct(Item.Settings settings, CallbackInfo info) {
-		FabricItemInternals.onBuild(settings, (Item) (Object) this);
-	}
-
-	@Override
-	public EquipmentSlotProvider fabric_getEquipmentSlotProvider() {
-		return equipmentSlotProvider;
-	}
-
-	@Override
-	public void fabric_setEquipmentSlotProvider(EquipmentSlotProvider equipmentSlotProvider) {
-		this.equipmentSlotProvider = equipmentSlotProvider;
+		FabricItemInternals.onBuild(settings, this);
 	}
 
 	@Override
-	public CustomDamageHandler fabric_getCustomDamageHandler() {
-		return customDamageHandler;
+	public @NotNull Map<CustomItemSetting<?>, Object> fabric_getCustomItemSettings() {
+		return this.customItemSettings;
 	}
 
 	@Override
-	public void fabric_setCustomDamageHandler(CustomDamageHandler handler) {
-		this.customDamageHandler = handler;
+	@SuppressWarnings("unchecked")
+	public <T> @NotNull T fabric_getCustomItemSetting(CustomItemSetting<T> type) {
+		return (T) this.customItemSettings.computeIfAbsent(type, CustomItemSetting::getDefaultValue);
 	}
 }

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/ItemStackMixin.java

@@ -30,8 +30,8 @@
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 
+import net.fabricmc.fabric.impl.item.FabricItemInternals;
 import net.fabricmc.fabric.api.item.v1.CustomDamageHandler;
-import net.fabricmc.fabric.impl.item.ItemExtensions;
 
 @Mixin(ItemStack.class)
 public abstract class ItemStackMixin {
@@ -51,7 +51,7 @@ private void saveDamager(int amount, LivingEntity entity, Consumer<LivingEntity>
 
 	@ModifyArg(method = "damage(ILnet/minecraft/entity/LivingEntity;Ljava/util/function/Consumer;)V", at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;damage(ILjava/util/Random;Lnet/minecraft/server/network/ServerPlayerEntity;)Z"), index = 0)
 	private int hookDamage(int amount) {
-		CustomDamageHandler handler = ((ItemExtensions) getItem()).fabric_getCustomDamageHandler();
+		CustomDamageHandler handler = FabricItemInternals.CUSTOM_DAMAGE_HANDLER.getValue(this.getItem());
 
 		if (handler != null) {
 			return handler.damage((ItemStack) (Object) this, amount, fabric_damagingEntity, fabric_breakCallback);

fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/MobEntityMixin.java

@@ -27,14 +27,14 @@
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 
+import net.fabricmc.fabric.impl.item.FabricItemInternals;
 import net.fabricmc.fabric.api.item.v1.EquipmentSlotProvider;
-import net.fabricmc.fabric.impl.item.ItemExtensions;
 
 @Mixin(MobEntity.class)
 abstract class MobEntityMixin {
 	@Inject(method = "getPreferredEquipmentSlot", at = @At(value = "INVOKE_ASSIGN", target = "Lnet/minecraft/item/ItemStack;getItem()Lnet/minecraft/item/Item;"), cancellable = true, locals = LocalCapture.CAPTURE_FAILHARD)
 	private static void onGetPreferredEquipmentSlot(ItemStack stack, CallbackInfoReturnable<EquipmentSlot> info, Item item) {
-		EquipmentSlotProvider equipmentSlotProvider = ((ItemExtensions) item).fabric_getEquipmentSlotProvider();
+		EquipmentSlotProvider equipmentSlotProvider = FabricItemInternals.EQUIPMENT_SLOT_PROVIDER.getValue(item);
 
 		if (equipmentSlotProvider != null) {
 			info.setReturnValue(equipmentSlotProvider.getPreferredEquipmentSlot(stack));

fabric-item-api-v1/src/testmod/java/net/fabricmc/fabric/test/item/FabricItemSettingsTests.java

@@ -24,12 +24,18 @@
 
 import net.fabricmc.api.ModInitializer;
 import net.fabricmc.fabric.api.item.v1.FabricItemSettings;
+import net.fabricmc.fabric.api.item.v1.CustomItemSetting;
 
 public class FabricItemSettingsTests implements ModInitializer {
+	public static final CustomItemSetting<String> CUSTOM_DATA_TEST = CustomItemSetting.of(() -> null);
+
 	@Override
 	public void onInitialize() {
 		// Registers an item with a custom equipment slot.
 		Item testItem = new Item(new FabricItemSettings().group(ItemGroup.MISC).equipmentSlot(stack -> EquipmentSlot.CHEST));
 		Registry.register(Registry.ITEM, new Identifier("fabric-item-api-v1-testmod", "test_item"), testItem);
+
+		Item testItem2 = new Item(new FabricItemSettings().group(ItemGroup.MISC).customSetting(CUSTOM_DATA_TEST, "Look at me! I have a custom setting!"));
+		Registry.register(Registry.ITEM, new Identifier("fabric-item-api-v1-testmod", "test_item2"), testItem2);
 	}
 }

fabric-item-api-v1/src/testmod/java/net/fabricmc/fabric/test/item/client/TooltipTests.java

@@ -22,6 +22,7 @@
 import net.fabricmc.api.ClientModInitializer;
 import net.fabricmc.api.EnvType;
 import net.fabricmc.api.Environment;
+import net.fabricmc.fabric.test.item.FabricItemSettingsTests;
 import net.fabricmc.fabric.api.client.item.v1.ItemTooltipCallback;
 
 @Environment(EnvType.CLIENT)
@@ -31,6 +32,12 @@ public void onInitializeClient() {
 		// Adds a tooltip to all items so testing can be verified easily.
 		ItemTooltipCallback.EVENT.register((stack, context, lines) -> {
 			lines.add(new LiteralText("Fancy Tooltips").formatted(Formatting.LIGHT_PURPLE));
+
+			String string = FabricItemSettingsTests.CUSTOM_DATA_TEST.getValue(stack.getItem());
+
+			if (string != null) {
+				lines.add(new LiteralText(string));
+			}
 		});
 	}
 }

fabric-item-api-v1/src/testmod/resources/fabric.mod.json

@@ -10,13 +10,12 @@
   },
   "entrypoints": {
     "main": [
-      "net.fabricmc.fabric.test.item.FabricItemSettingsTests"
+      "net.fabricmc.fabric.test.item.FabricItemSettingsTests",
+      "net.fabricmc.fabric.test.item.CustomDamageTest"
+
     ],
     "client": [
       "net.fabricmc.fabric.test.item.client.TooltipTests"
-    ],
-    "main": [
-      "net.fabricmc.fabric.test.item.CustomDamageTest"
     ]
   }
 }