From 85719ab7b755fbe8144ead1c6d6b783eb7369507 Mon Sep 17 00:00:00 2001
From: frqnny <45723631+frqnny@users.noreply.github.com>
Date: Fri, 20 May 2022 13:17:48 -0400
Subject: [PATCH] Add ModifyItemAttributeModifiersCallback (#2175)
* Add ItemAttributeModifiersCallback
* fix checkstyle errors
* fix checkstyle errors v2
* Edit javadoc per Technician's review
* Update fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/ItemAttributeModifiersCallback.java
Co-authored-by: Juuxel <6596629+Juuxel@users.noreply.github.com>
* Change functional interface name per Juuz's review
* Change name to ModifyItemAttributeModifiers per Juuz and Technician's request
* Forgot to add callback to the name
* Return mutable map
* Remove unused import
Co-authored-by: Juuxel <6596629+Juuxel@users.noreply.github.com>
---
.../ModifyItemAttributeModifiersCallback.java | 59 +++++++++++++++++++
.../fabric/mixin/item/ItemStackMixin.java | 8 ++-
...ifyItemAttributeModifiersCallbackTest.java | 38 ++++++++++++
.../src/testmod/resources/fabric.mod.json | 3 +-
4 files changed, 106 insertions(+), 2 deletions(-)
create mode 100644 fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/ModifyItemAttributeModifiersCallback.java
create mode 100644 fabric-item-api-v1/src/testmod/java/net/fabricmc/fabric/test/item/ModifyItemAttributeModifiersCallbackTest.java
diff --git a/fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/ModifyItemAttributeModifiersCallback.java b/fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/ModifyItemAttributeModifiersCallback.java
new file mode 100644
index 000000000..2c0a2475f
--- /dev/null
+++ b/fabric-item-api-v1/src/main/java/net/fabricmc/fabric/api/item/v1/ModifyItemAttributeModifiersCallback.java
@@ -0,0 +1,59 @@
+/*
+ * 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 com.google.common.collect.Multimap;
+
+import net.minecraft.entity.EquipmentSlot;
+import net.minecraft.entity.attribute.EntityAttribute;
+import net.minecraft.entity.attribute.EntityAttributeModifier;
+import net.minecraft.item.ItemStack;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.api.event.EventFactory;
+
+/**
+ * Stack-aware attribute modifier callback for foreign items.
+ * Instead of using Mixin to change attribute modifiers in items not in your mod,
+ * you can use this event instead, either checking the Item itself or using a tag.
+ * This event provides you with a guaranteed mutable map you can put attribute modifiers in.
+ * Do not use for your own Item classes; see {@link FabricItem#getAttributeModifiers} instead.
+ * For example, the following code modifies a Diamond Helmet to give you five extra hearts when wearing.
+ *
+ * <pre>
+ * {@code
+ * ModifyItemAttributeModifiersCallback.EVENT.register((stack, slot, attributeModifiers) -> {
+ * if (stack.isOf(Items.DIAMOND_HELMET) && slot.getEntitySlotId() == HEAD_SLOT_ID) {
+ * attributeModifiers.put(EntityAttributes.GENERIC_MAX_HEALTH, MODIFIER);
+ * }
+ * });
+ * }
+ * </pre>
+ */
+@FunctionalInterface
+public interface ModifyItemAttributeModifiersCallback {
+ void modifyAttributeModifiers(ItemStack stack, EquipmentSlot slot, Multimap<EntityAttribute, EntityAttributeModifier> attributeModifiers);
+
+ Event<ModifyItemAttributeModifiersCallback> EVENT = EventFactory.createArrayBacked(
+ ModifyItemAttributeModifiersCallback.class,
+ callbacks -> (stack, slot, attributeModifiers) -> {
+ for (ModifyItemAttributeModifiersCallback callback : callbacks) {
+ callback.modifyAttributeModifiers(stack, slot, attributeModifiers);
+ }
+ }
+ );
+}
diff --git a/fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/ItemStackMixin.java b/fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/ItemStackMixin.java
index e0b559dc4..570236465 100644
--- a/fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/ItemStackMixin.java
+++ b/fabric-item-api-v1/src/main/java/net/fabricmc/fabric/mixin/item/ItemStackMixin.java
@@ -18,6 +18,7 @@ package net.fabricmc.fabric.mixin.item;
import java.util.function.Consumer;
+import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.Shadow;
@@ -37,6 +38,7 @@ import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.fabricmc.fabric.api.item.v1.CustomDamageHandler;
+import net.fabricmc.fabric.api.item.v1.ModifyItemAttributeModifiersCallback;
import net.fabricmc.fabric.impl.item.ItemExtensions;
@Mixin(ItemStack.class)
@@ -80,7 +82,11 @@ public abstract class ItemStackMixin {
)
)
public Multimap<EntityAttribute, EntityAttributeModifier> hookGetAttributeModifiers(Item item, EquipmentSlot slot) {
- return item.getAttributeModifiers((ItemStack) (Object) this, slot);
+ ItemStack stack = (ItemStack) (Object) this;
+ //we need to ensure it is modifiable for the callback
+ Multimap<EntityAttribute, EntityAttributeModifier> attributeModifiers = HashMultimap.create(item.getAttributeModifiers(stack, slot));
+ ModifyItemAttributeModifiersCallback.EVENT.invoker().modifyAttributeModifiers(stack, slot, attributeModifiers);
+ return attributeModifiers;
}
@Redirect(
diff --git a/fabric-item-api-v1/src/testmod/java/net/fabricmc/fabric/test/item/ModifyItemAttributeModifiersCallbackTest.java b/fabric-item-api-v1/src/testmod/java/net/fabricmc/fabric/test/item/ModifyItemAttributeModifiersCallbackTest.java
new file mode 100644
index 000000000..72e54d9cd
--- /dev/null
+++ b/fabric-item-api-v1/src/testmod/java/net/fabricmc/fabric/test/item/ModifyItemAttributeModifiersCallbackTest.java
@@ -0,0 +1,38 @@
+/*
+ * 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.test.item;
+
+import net.minecraft.entity.attribute.EntityAttributeModifier;
+import net.minecraft.entity.attribute.EntityAttributes;
+import net.minecraft.item.Items;
+
+import net.fabricmc.api.ModInitializer;
+import net.fabricmc.fabric.api.item.v1.ModifyItemAttributeModifiersCallback;
+
+public class ModifyItemAttributeModifiersCallbackTest implements ModInitializer {
+ public static final int HEAD_SLOT_ID = 3;
+ public static final EntityAttributeModifier MODIFIER = new EntityAttributeModifier("generic_max_health_modifier", 5.0, EntityAttributeModifier.Operation.ADDITION);
+
+ @Override
+ public void onInitialize() {
+ ModifyItemAttributeModifiersCallback.EVENT.register((stack, slot, attributeModifiers) -> {
+ if (stack.isOf(Items.DIAMOND_HELMET) && slot.getEntitySlotId() == HEAD_SLOT_ID) {
+ attributeModifiers.put(EntityAttributes.GENERIC_MAX_HEALTH, MODIFIER);
+ }
+ });
+ }
+}
diff --git a/fabric-item-api-v1/src/testmod/resources/fabric.mod.json b/fabric-item-api-v1/src/testmod/resources/fabric.mod.json
index ec34716a1..2750b292a 100644
--- a/fabric-item-api-v1/src/testmod/resources/fabric.mod.json
+++ b/fabric-item-api-v1/src/testmod/resources/fabric.mod.json
@@ -12,7 +12,8 @@
"main": [
"net.fabricmc.fabric.test.item.CustomDamageTest",
"net.fabricmc.fabric.test.item.FabricItemSettingsTests",
- "net.fabricmc.fabric.test.item.ItemUpdateAnimationTest"
+ "net.fabricmc.fabric.test.item.ItemUpdateAnimationTest",
+ "net.fabricmc.fabric.test.item.ModifyItemAttributeModifiersCallbackTest"
],
"client": [
"net.fabricmc.fabric.test.item.client.TooltipTests"