Remove FabricItem and add an item setting instead

checkstyle.xml

@@ -199,7 +199,10 @@
 
 		<!--<module name="InvalidJavadocPosition"/>-->
 		<module name="JavadocParagraph"/>
-		<module name="JavadocStyle"/>
+		<module name="JavadocStyle">
+			<!-- "First sentence should end with a period." conflicts with the new Java 16 {@return ...}. -->
+			<property name="checkFirstSentence" value="false"/>
+		</module>
 		<module name="AtclauseOrder">
 			<property name="tagOrder" value="@param,@return,@throws,@deprecated"/>
 		</module>

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

@@ -53,6 +53,15 @@ public class FabricItemSettings extends Item.Settings {
 		return this;
 	}
 
+	/**
+	 * Allow cancelling the client-side animation when the NBT or count of this stack changes.
+	 * @see UpdateAnimationHandler
+	 */
+	public FabricItemSettings nbtUpdateAnimation(UpdateAnimationHandler handler) {
+		FabricItemInternals.computeExtraData(this).nbtUpdateAnimation(handler);
+		return this;
+	}
+
 	// Overrides of vanilla methods
 
 	@Override

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

@@ -18,33 +18,25 @@ package net.fabricmc.fabric.api.item.v1;
 
 import net.minecraft.client.network.ClientPlayerEntity;
 import net.minecraft.entity.player.PlayerEntity;
-import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.Hand;
 
 /**
- * General-purpose Fabric-provided extensions for {@link Item} subclasses.
+ * When the NBT of an item stack in the main hand or off hand changes, vanilla runs an "update animation".
+ * If registered, an instance is called on the client side when the NBT or count of the stack has changed, but not the item,
+ * and returning true allows canceling this animation.
  *
- * <p>Note: This interface is automatically implemented on all items via Mixin,
- * however it has to be implemented explicitly by modders to be able to override functions.
- * In the future, it is planned that {@code public class Item implements FabricItem} will be visible in a development environment.
- *
- * <p>Note to maintainers: Functions should only be added to this interface if they are general-purpose enough,
- * to be evaluated on a case-by-case basis. Otherwise they are better suited for more specialized APIs.
+ * <p>Can be set with {@link FabricItemSettings#nbtUpdateAnimation}.
  */
-public interface FabricItem {
+@FunctionalInterface
+public interface UpdateAnimationHandler {
 	/**
-	 * When the NBT of an item stack in the main hand or off hand changes, vanilla runs an "update animation".
-	 * This function is called on the client side when the NBT or count of the stack has changed, but not the item,
-	 * and returning true allows canceling this animation.
+	 * {@return true to run the vanilla NBT update animation, false to cancel it}
 	 *
 	 * @param player   the current player; this may be safely cast to {@link ClientPlayerEntity} in client-only code
 	 * @param hand     the hand; this function applies both to the main hand and the off hand
 	 * @param oldStack the previous stack, of this item
 	 * @param newStack the new stack, also of this item
-	 * @return true to run the vanilla animation, false to cancel it.
 	 */
-	default boolean allowNbtUpdateAnimation(PlayerEntity player, Hand hand, ItemStack oldStack, ItemStack newStack) {
-		return true;
-	}
+	boolean allowNbtUpdateAnimation(PlayerEntity player, Hand hand, ItemStack oldStack, ItemStack newStack);
 }

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

@@ -18,10 +18,13 @@ package net.fabricmc.fabric.impl.item;
 
 import java.util.WeakHashMap;
 
+import org.jetbrains.annotations.Nullable;
+
 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.api.item.v1.UpdateAnimationHandler;
 
 public final class FabricItemInternals {
 	private static final WeakHashMap<Item.Settings, ExtraData> extraData = new WeakHashMap<>();
@@ -39,12 +42,17 @@ public final class FabricItemInternals {
 		if (data != null) {
 			((ItemExtensions) item).fabric_setEquipmentSlotProvider(data.equipmentSlotProvider);
 			((ItemExtensions) item).fabric_setCustomDamageHandler(data.customDamageHandler);
+			((ItemExtensions) item).fabric_setUpdateAnimationHandler(data.updateAnimationHandler);
 		}
 	}
 
 	public static final class ExtraData {
-		private /* @Nullable */ EquipmentSlotProvider equipmentSlotProvider;
-		private /* @Nullable */ CustomDamageHandler customDamageHandler;
+		@Nullable
+		private EquipmentSlotProvider equipmentSlotProvider;
+		@Nullable
+		private CustomDamageHandler customDamageHandler;
+		@Nullable
+		private UpdateAnimationHandler updateAnimationHandler;
 
 		public void equipmentSlot(EquipmentSlotProvider equipmentSlotProvider) {
 			this.equipmentSlotProvider = equipmentSlotProvider;
@@ -53,5 +61,9 @@ public final class FabricItemInternals {
 		public void customDamage(CustomDamageHandler handler) {
 			this.customDamageHandler = handler;
 		}
+
+		public void nbtUpdateAnimation(UpdateAnimationHandler handler) {
+			this.updateAnimationHandler = handler;
+		}
 	}
 }

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

@@ -16,12 +16,22 @@
 
 package net.fabricmc.fabric.impl.item;
 
+import org.jetbrains.annotations.Nullable;
+
 import net.fabricmc.fabric.api.item.v1.CustomDamageHandler;
 import net.fabricmc.fabric.api.item.v1.EquipmentSlotProvider;
+import net.fabricmc.fabric.api.item.v1.UpdateAnimationHandler;
 
 public interface ItemExtensions {
-	/* @Nullable */ EquipmentSlotProvider fabric_getEquipmentSlotProvider();
+	@Nullable
+	EquipmentSlotProvider fabric_getEquipmentSlotProvider();
 	void fabric_setEquipmentSlotProvider(EquipmentSlotProvider equipmentSlotProvider);
-	/* @Nullable */ CustomDamageHandler fabric_getCustomDamageHandler();
+
+	@Nullable
+	CustomDamageHandler fabric_getCustomDamageHandler();
 	void fabric_setCustomDamageHandler(CustomDamageHandler handler);
+
+	@Nullable
+	UpdateAnimationHandler fabric_getUpdateAnimationHandler();
+	void fabric_setUpdateAnimationHandler(UpdateAnimationHandler handler);
 }

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

@@ -16,6 +16,7 @@
 
 package net.fabricmc.fabric.mixin.item;
 
+import org.jetbrains.annotations.Nullable;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Unique;
 import org.spongepowered.asm.mixin.injection.At;
@@ -26,17 +27,20 @@ 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.api.item.v1.FabricItem;
+import net.fabricmc.fabric.api.item.v1.UpdateAnimationHandler;
 import net.fabricmc.fabric.impl.item.FabricItemInternals;
 import net.fabricmc.fabric.impl.item.ItemExtensions;
 
 @Mixin(Item.class)
-abstract class ItemMixin implements ItemExtensions, FabricItem {
+abstract class ItemMixin implements ItemExtensions {
 	@Unique
-	private EquipmentSlotProvider equipmentSlotProvider;
+	private EquipmentSlotProvider fabric_equipmentSlotProvider;
 
 	@Unique
-	private CustomDamageHandler customDamageHandler;
+	private CustomDamageHandler fabric_customDamageHandler;
+
+	@Unique
+	private UpdateAnimationHandler fabric_updateAnimationHandler;
 
 	@Inject(method = "<init>", at = @At("RETURN"))
 	private void onConstruct(Item.Settings settings, CallbackInfo info) {
@@ -45,21 +49,31 @@ abstract class ItemMixin implements ItemExtensions, FabricItem {
 
 	@Override
 	public EquipmentSlotProvider fabric_getEquipmentSlotProvider() {
-		return equipmentSlotProvider;
+		return fabric_equipmentSlotProvider;
 	}
 
 	@Override
 	public void fabric_setEquipmentSlotProvider(EquipmentSlotProvider equipmentSlotProvider) {
-		this.equipmentSlotProvider = equipmentSlotProvider;
+		this.fabric_equipmentSlotProvider = equipmentSlotProvider;
 	}
 
 	@Override
 	public CustomDamageHandler fabric_getCustomDamageHandler() {
-		return customDamageHandler;
+		return fabric_customDamageHandler;
 	}
 
 	@Override
 	public void fabric_setCustomDamageHandler(CustomDamageHandler handler) {
-		this.customDamageHandler = handler;
+		this.fabric_customDamageHandler = handler;
+	}
+
+	@Override
+	public @Nullable UpdateAnimationHandler fabric_getUpdateAnimationHandler() {
+		return fabric_updateAnimationHandler;
+	}
+
+	@Override
+	public void fabric_setUpdateAnimationHandler(UpdateAnimationHandler handler) {
+		this.fabric_updateAnimationHandler = handler;
 	}
 }

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

@@ -19,20 +19,21 @@ package net.fabricmc.fabric.mixin.item.client;
 import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 import net.minecraft.client.MinecraftClient;
 import net.minecraft.client.render.item.HeldItemRenderer;
-import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.ItemStack;
 import net.minecraft.util.Hand;
 
-import net.fabricmc.fabric.api.item.v1.FabricItem;
+import net.fabricmc.fabric.api.item.v1.UpdateAnimationHandler;
+import net.fabricmc.fabric.impl.item.ItemExtensions;
 
 /**
- * Allow canceling the held item update animation if {@link FabricItem#allowNbtUpdateAnimation} returns false.
+ * Allow canceling the held item update animation if {@link UpdateAnimationHandler#allowNbtUpdateAnimation} returns false.
  */
 @Mixin(HeldItemRenderer.class)
 public class HeldItemRendererMixin {
@@ -51,19 +52,28 @@ public class HeldItemRendererMixin {
 		// Modify main hand
 		ItemStack newMainStack = client.player.getMainHandStack();
 
-		if (mainHand.getItem() == newMainStack.getItem()) {
-			if (!((FabricItem) mainHand.getItem()).allowNbtUpdateAnimation(client.player, Hand.MAIN_HAND, mainHand, newMainStack)) {
-				mainHand = newMainStack;
-			}
+		if (suppressUpdate(Hand.MAIN_HAND, mainHand, newMainStack)) {
+			mainHand = newMainStack;
 		}
 
 		// Modify off hand
 		ItemStack newOffStack = client.player.getOffHandStack();
 
-		if (offHand.getItem() == newOffStack.getItem()) {
-			if (!((FabricItem) offHand.getItem()).allowNbtUpdateAnimation(client.player, Hand.OFF_HAND, offHand, newOffStack)) {
-				offHand = newOffStack;
-			}
+		if (suppressUpdate(Hand.OFF_HAND, offHand, newOffStack)) {
+			offHand = newOffStack;
 		}
 	}
+
+	@Unique
+	private boolean suppressUpdate(Hand hand, ItemStack oldStack, ItemStack newStack) {
+		if (oldStack.getItem() == newStack.getItem()) {
+			UpdateAnimationHandler handler = ((ItemExtensions) oldStack.getItem()).fabric_getUpdateAnimationHandler();
+
+			if (handler != null) {
+				return !handler.allowNbtUpdateAnimation(client.player, hand, oldStack, newStack);
+			}
+		}
+
+		return false;
+	}
 }

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

@@ -17,22 +17,17 @@
 package net.fabricmc.fabric.test.item;
 
 import net.minecraft.entity.Entity;
-import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemGroup;
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.NbtCompound;
-import net.minecraft.util.Hand;
 import net.minecraft.world.World;
 
-import net.fabricmc.fabric.api.item.v1.FabricItem;
-
-public class UpdatingItem extends Item implements FabricItem {
-	private final boolean allowUpdateAnimation;
+import net.fabricmc.fabric.api.item.v1.FabricItemSettings;
 
+public class UpdatingItem extends Item {
 	public UpdatingItem(boolean allowUpdateAnimation) {
-		super(new Settings().group(ItemGroup.MISC));
-		this.allowUpdateAnimation = allowUpdateAnimation;
+		super(new FabricItemSettings().group(ItemGroup.MISC).nbtUpdateAnimation((p, h, o, n) -> allowUpdateAnimation));
 	}
 
 	@Override
@@ -42,9 +37,4 @@ public class UpdatingItem extends Item implements FabricItem {
 			tag.putLong("ticks", tag.getLong("ticks")+1);
 		}
 	}
-
-	@Override
-	public boolean allowNbtUpdateAnimation(PlayerEntity player, Hand hand, ItemStack originalStack, ItemStack updatedStack) {
-		return allowUpdateAnimation;
-	}
 }