Add ForgeSpawnEggItem to lazily handle EntityTypes (#8044)

src/main/java/net/minecraftforge/common/ForgeSpawnEggItem.java

@@ -0,0 +1,132 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2021.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.common;
+
+import net.minecraft.core.Direction;
+import net.minecraft.core.dispenser.DispenseItemBehavior;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.world.entity.EntityType;
+import net.minecraft.world.entity.Mob;
+import net.minecraft.world.entity.MobSpawnType;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.SpawnEggItem;
+import net.minecraft.world.level.block.DispenserBlock;
+import net.minecraft.world.level.gameevent.GameEvent;
+import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.client.event.ColorHandlerEvent;
+import net.minecraftforge.eventbus.api.EventPriority;
+import net.minecraftforge.eventbus.api.SubscribeEvent;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.event.lifecycle.FMLCommonSetupEvent;
+
+import javax.annotation.Nullable;
+import java.util.ArrayList;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Supplier;
+
+public class ForgeSpawnEggItem extends SpawnEggItem
+{
+    private static final List<ForgeSpawnEggItem> MOD_EGGS = new ArrayList<>();
+    private static final Map<EntityType<? extends Mob>, ForgeSpawnEggItem> TYPE_MAP = new IdentityHashMap<>();
+    private final Supplier<? extends EntityType<? extends Mob>> typeSupplier;
+
+    public ForgeSpawnEggItem(Supplier<? extends EntityType<? extends Mob>> type, int backgroundColor, int highlightColor, Properties props)
+    {
+        super((EntityType<? extends Mob>) null, backgroundColor, highlightColor, props);
+        this.typeSupplier = type;
+
+        MOD_EGGS.add(this);
+    }
+
+    @Override
+    public EntityType<?> getType(@Nullable CompoundTag tag)
+    {
+        EntityType<?> type = super.getType(tag);
+        return type != null ? type : typeSupplier.get();
+    }
+
+    @Nullable
+    protected DispenseItemBehavior createDispenseBehavior()
+    {
+        return DEFAULT_DISPENSE_BEHAVIOR;
+    }
+
+    @Nullable
+    public static SpawnEggItem fromEntityType(@Nullable EntityType<?> type)
+    {
+        SpawnEggItem ret = TYPE_MAP.get(type);
+        return ret != null ? ret : SpawnEggItem.byId(type);
+    }
+
+
+
+    private static final DispenseItemBehavior DEFAULT_DISPENSE_BEHAVIOR = (source, stack) ->
+    {
+        Direction face = source.getBlockState().getValue(DispenserBlock.FACING);
+        EntityType<?> type = ((SpawnEggItem)stack.getItem()).getType(stack.getTag());
+
+        try
+        {
+            type.spawn(source.getLevel(), stack, null, source.getPos().relative(face), MobSpawnType.DISPENSER, face != Direction.UP, false);
+        }
+        catch (Exception exception)
+        {
+            DispenseItemBehavior.LOGGER.error("Error while dispensing spawn egg from dispenser at {}", source.getPos(), exception);
+            return ItemStack.EMPTY;
+        }
+
+        stack.shrink(1);
+        source.getLevel().gameEvent(GameEvent.ENTITY_PLACE, source.getPos());
+        return stack;
+    };
+
+    @Mod.EventBusSubscriber(modid = "forge", bus = Mod.EventBusSubscriber.Bus.MOD)
+    private static class CommonHandler
+    {
+        @SubscribeEvent
+        public static void onCommonSetup(FMLCommonSetupEvent event)
+        {
+            MOD_EGGS.forEach(egg ->
+            {
+                DispenseItemBehavior dispenseBehavior = egg.createDispenseBehavior();
+                if (dispenseBehavior != null)
+                {
+                    DispenserBlock.registerBehavior(egg, dispenseBehavior);
+                }
+
+                TYPE_MAP.put(egg.typeSupplier.get(), egg);
+            });
+        }
+    }
+
+    @Mod.EventBusSubscriber(value = Dist.CLIENT, modid = "forge", bus = Mod.EventBusSubscriber.Bus.MOD)
+    private static class ColorRegisterHandler
+    {
+        @SubscribeEvent(priority = EventPriority.HIGHEST)
+        public static void registerSpawnEggColors(ColorHandlerEvent.Item event)
+        {
+            MOD_EGGS.forEach(egg ->
+                    event.getItemColors().register((stack, layer) -> egg.getColor(layer), egg)
+            );
+        }
+    }
+}

src/main/java/net/minecraftforge/common/extensions/IForgeEntity.java

@@ -30,6 +30,7 @@ import net.minecraft.world.item.ItemStack;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.core.BlockPos;
 import net.minecraft.world.phys.HitResult;
+import net.minecraftforge.common.ForgeSpawnEggItem;
 import net.minecraftforge.common.capabilities.ICapabilitySerializable;
 import net.minecraftforge.entity.PartEntity;
 
@@ -87,7 +88,7 @@ public interface IForgeEntity extends ICapabilitySerializable<CompoundTag>
     {
         ItemStack result = self().getPickResult();
         if (result == null) {
-            SpawnEggItem egg = SpawnEggItem.byId(self().getType());
+            SpawnEggItem egg = ForgeSpawnEggItem.fromEntityType(self().getType());
             if (egg != null)
                 result = new ItemStack(egg);
             else