Added on itemPickup event

fabric-lifecycle-events-v1/src/main/java/net/fabricmc/fabric/api/event/lifecycle/v1/ServerEntityEvents.java

@@ -18,7 +18,9 @@
 
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.EquipmentSlot;
+import net.minecraft.entity.ItemEntity;
 import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.ItemStack;
 import net.minecraft.server.world.ServerWorld;
 
@@ -63,6 +65,28 @@ private ServerEntityEvents() {
 		}
 	});
 
+	/**
+	 * Called during {@link ItemEntity#tick()} on the logical server if an entity tries to pick up any {@link ItemEntity}.
+	 *
+	 * <p>Picking up of an item is determined by {@link ItemEntity#onPlayerCollision(PlayerEntity)}.
+	 *
+	 * <p>Returning {@code false} prevents vanilla from handling the pick-up.
+	 */
+	public static final Event<ItemPickup> ITEM_PICKUP = EventFactory.createArrayBacked(
+			ItemPickup.class,
+			(callbacks) -> (playerEntity, itemEntity, itemStack) -> {
+				for (ItemPickup callback : callbacks) {
+					boolean shouldContinue = callback.onPickup(playerEntity, itemEntity, itemStack);
+
+					if (!shouldContinue) {
+						return false;
+					}
+				}
+
+				return true;
+			}
+	);
+
 	@FunctionalInterface
 	public interface Load {
 		void onLoad(Entity entity, ServerWorld world);
@@ -77,4 +101,9 @@ public interface Unload {
 	public interface EquipmentChange {
 		void onChange(LivingEntity livingEntity, EquipmentSlot equipmentSlot, ItemStack previousStack, ItemStack currentStack);
 	}
+
+	@FunctionalInterface
+	public interface ItemPickup {
+		boolean onPickup(PlayerEntity playerEntity, ItemEntity itemEntity, ItemStack itemStack);
+	}
 }

fabric-lifecycle-events-v1/src/main/java/net/fabricmc/fabric/mixin/event/lifecycle/ItemEntityMixin.java

@@ -0,0 +1,40 @@
+/*
+ * 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.mixin.event.lifecycle;
+
+import org.spongepowered.asm.mixin.Mixin;
+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.entity.ItemEntity;
+import net.minecraft.entity.player.PlayerEntity;
+
+import net.fabricmc.fabric.api.event.lifecycle.v1.ServerEntityEvents;
+
+@Mixin(ItemEntity.class)
+public class ItemEntityMixin {
+	@Inject(method = "onPlayerCollision", at = @At(value = "INVOKE", target = "Lnet/minecraft/entity/player/PlayerInventory;insertStack(Lnet/minecraft/item/ItemStack;)Z"), cancellable = true)
+	private void onPlayerPickup(PlayerEntity playerEntity, CallbackInfo ci) {
+		ItemEntity itemEntity = (ItemEntity) (Object) this;
+		boolean allowPickup = ServerEntityEvents.ITEM_PICKUP.invoker().onPickup(playerEntity, itemEntity, itemEntity.getStack());
+
+		if (!allowPickup) {
+			ci.cancel();
+		}
+	}
+}

fabric-lifecycle-events-v1/src/main/resources/fabric-lifecycle-events-v1.mixins.json

@@ -6,6 +6,7 @@
     "ChunkGeneratingMixin",
     "ChunkHolderMixin",
     "DataPackContentsMixin",
+    "ItemEntityMixin",
     "LivingEntityMixin",
     "MinecraftServerMixin",
     "PlayerManagerMixin",