Add support for basic entity picking via middle-click (#5397)

Support for more advanced stuff like NBT copying wasn't added in this PR, as the NBT used by PM is currently an inconsistent mess and doesn't play nice with vanilla. In the interests of avoiding this mess propagating, it's been left for another time.

Adds PlayerEntityPickEvent a la PlayerBlockPickEvent
and Entity->getPickedItem().

src/entity/Entity.php

@@ -35,6 +35,7 @@ use pocketmine\event\entity\EntityMotionEvent;
 use pocketmine\event\entity\EntityRegainHealthEvent;
 use pocketmine\event\entity\EntitySpawnEvent;
 use pocketmine\event\entity\EntityTeleportEvent;
+use pocketmine\item\Item;
 use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Facing;
 use pocketmine\math\Vector2;
@@ -1560,6 +1561,13 @@ abstract class Entity{
 		$this->hasSpawned = [];
 	}
 
+	/**
+	 * Returns the item that players will equip when middle-clicking on this entity.
+	 */
+	public function getPickedItem() : ?Item{
+		return null;
+	}
+
 	/**
 	 * Flags the entity to be removed from the world on the next tick.
 	 */

src/entity/Squid.php

@@ -26,6 +26,7 @@ namespace pocketmine\entity;
 use pocketmine\entity\animation\SquidInkCloudAnimation;
 use pocketmine\event\entity\EntityDamageByEntityEvent;
 use pocketmine\event\entity\EntityDamageEvent;
+use pocketmine\item\Item;
 use pocketmine\item\VanillaItems;
 use pocketmine\math\Vector3;
 use pocketmine\nbt\tag\CompoundTag;
@@ -124,4 +125,8 @@ class Squid extends WaterAnimal{
 			VanillaItems::INK_SAC()->setCount(mt_rand(1, 3))
 		];
 	}
+
+	public function getPickedItem() : ?Item{
+		return VanillaItems::SQUID_SPAWN_EGG();
+	}
 }

src/entity/Villager.php

@@ -23,6 +23,8 @@ declare(strict_types=1);
 
 namespace pocketmine\entity;
 
+use pocketmine\item\Item;
+use pocketmine\item\VanillaItems;
 use pocketmine\nbt\tag\CompoundTag;
 use pocketmine\network\mcpe\protocol\types\entity\EntityIds;
 use pocketmine\network\mcpe\protocol\types\entity\EntityMetadataCollection;
@@ -87,6 +89,10 @@ class Villager extends Living implements Ageable{
 		return $this->baby;
 	}
 
+	public function getPickedItem() : ?Item{
+		return VanillaItems::VILLAGER_SPAWN_EGG();
+	}
+
 	protected function syncNetworkData(EntityMetadataCollection $properties) : void{
 		parent::syncNetworkData($properties);
 		$properties->setGenericFlag(EntityMetadataFlags::BABY, $this->baby);

src/entity/Zombie.php

@@ -23,6 +23,7 @@ declare(strict_types=1);
 
 namespace pocketmine\entity;
 
+use pocketmine\item\Item;
 use pocketmine\item\VanillaItems;
 use pocketmine\network\mcpe\protocol\types\entity\EntityIds;
 use function mt_rand;
@@ -65,4 +66,8 @@ class Zombie extends Living{
 		//TODO: check for equipment and whether it's a baby
 		return 5;
 	}
+
+	public function getPickedItem() : ?Item{
+		return VanillaItems::ZOMBIE_SPAWN_EGG();
+	}
 }

src/entity/object/FallingBlock.php

@@ -35,6 +35,7 @@ use pocketmine\entity\Location;
 use pocketmine\event\entity\EntityBlockChangeEvent;
 use pocketmine\event\entity\EntityDamageByEntityEvent;
 use pocketmine\event\entity\EntityDamageEvent;
+use pocketmine\item\Item;
 use pocketmine\math\Vector3;
 use pocketmine\nbt\tag\ByteTag;
 use pocketmine\nbt\tag\CompoundTag;
@@ -194,6 +195,10 @@ class FallingBlock extends Entity{
 		return $nbt;
 	}
 
+	public function getPickedItem() : ?Item{
+		return $this->block->asItem();
+	}
+
 	protected function syncNetworkData(EntityMetadataCollection $properties) : void{
 		parent::syncNetworkData($properties);
 

src/entity/object/Painting.php

@@ -28,6 +28,7 @@ use pocketmine\entity\Entity;
 use pocketmine\entity\EntitySizeInfo;
 use pocketmine\entity\Location;
 use pocketmine\event\entity\EntityDamageByEntityEvent;
+use pocketmine\item\Item;
 use pocketmine\item\VanillaItems;
 use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Facing;
@@ -165,6 +166,10 @@ class Painting extends Entity{
 		));
 	}
 
+	public function getPickedItem() : ?Item{
+		return VanillaItems::PAINTING();
+	}
+
 	/**
 	 * Returns the painting motive (which image is displayed on the painting)
 	 */

src/entity/object/PrimedTNT.php

@@ -23,11 +23,13 @@ declare(strict_types=1);
 
 namespace pocketmine\entity\object;
 
+use pocketmine\block\VanillaBlocks;
 use pocketmine\entity\Entity;
 use pocketmine\entity\EntitySizeInfo;
 use pocketmine\entity\Explosive;
 use pocketmine\event\entity\EntityDamageEvent;
 use pocketmine\event\entity\EntityPreExplodeEvent;
+use pocketmine\item\Item;
 use pocketmine\math\Vector3;
 use pocketmine\nbt\tag\CompoundTag;
 use pocketmine\network\mcpe\protocol\types\entity\EntityIds;
@@ -127,6 +129,10 @@ class PrimedTNT extends Entity implements Explosive{
 		}
 	}
 
+	public function getPickedItem() : ?Item{
+		return VanillaBlocks::TNT()->setWorksUnderwater($this->worksUnderwater)->asItem();
+	}
+
 	protected function syncNetworkData(EntityMetadataCollection $properties) : void{
 		parent::syncNetworkData($properties);
 

src/event/player/PlayerEntityPickEvent.php

@@ -0,0 +1,53 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program 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, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+ */
+
+declare(strict_types=1);
+
+namespace pocketmine\event\player;
+
+use pocketmine\entity\Entity;
+use pocketmine\event\Cancellable;
+use pocketmine\event\CancellableTrait;
+use pocketmine\item\Item;
+use pocketmine\player\Player;
+
+/**
+ * Called when a player middle-clicks on an entity to get an item in creative mode.
+ */
+class PlayerEntityPickEvent extends PlayerEvent implements Cancellable{
+	use CancellableTrait;
+
+	public function __construct(
+		Player $player,
+		private Entity $entityClicked,
+		private Item $resultItem
+	){
+		$this->player = $player;
+	}
+
+	public function getEntity() : Entity{
+		return $this->entityClicked;
+	}
+
+	public function getResultItem() : Item{
+		return $this->resultItem;
+	}
+}

src/network/mcpe/handler/InGamePacketHandler.php

@@ -671,7 +671,7 @@ class InGamePacketHandler extends PacketHandler{
 	}
 
 	public function handleActorPickRequest(ActorPickRequestPacket $packet) : bool{
-		return false; //TODO
+		return $this->player->pickEntity($packet->actorUniqueId);
 	}
 
 	public function handlePlayerAction(PlayerActionPacket $packet) : bool{

src/player/Player.php

@@ -57,6 +57,7 @@ use pocketmine\event\player\PlayerDisplayNameChangeEvent;
 use pocketmine\event\player\PlayerDropItemEvent;
 use pocketmine\event\player\PlayerEmoteEvent;
 use pocketmine\event\player\PlayerEntityInteractEvent;
+use pocketmine\event\player\PlayerEntityPickEvent;
 use pocketmine\event\player\PlayerExhaustEvent;
 use pocketmine\event\player\PlayerGameModeChangeEvent;
 use pocketmine\event\player\PlayerInteractEvent;
@@ -1709,29 +1710,58 @@ class Player extends Human implements CommandSender, ChunkListener, IPlayer{
 		$ev->call();
 
 		if(!$ev->isCancelled()){
-			if($existingSlot !== -1){
-				if($existingSlot < $this->inventory->getHotbarSize()){
-					$this->inventory->setHeldItemIndex($existingSlot);
-				}else{
-					$this->inventory->swap($this->inventory->getHeldItemIndex(), $existingSlot);
-				}
-			}else{
-				$firstEmpty = $this->inventory->firstEmpty();
-				if($firstEmpty === -1){ //full inventory
-					$this->inventory->setItemInHand($item);
-				}elseif($firstEmpty < $this->inventory->getHotbarSize()){
-					$this->inventory->setItem($firstEmpty, $item);
-					$this->inventory->setHeldItemIndex($firstEmpty);
-				}else{
-					$this->inventory->swap($this->inventory->getHeldItemIndex(), $firstEmpty);
-					$this->inventory->setItemInHand($item);
-				}
-			}
+			$this->equipOrAddPickedItem($existingSlot, $item);
 		}
 
 		return true;
 	}
 
+	public function pickEntity(int $entityId) : bool{
+		$entity = $this->getWorld()->getEntity($entityId);
+		if($entity === null){
+			return true;
+		}
+
+		$item = $entity->getPickedItem();
+		if($item === null){
+			return true;
+		}
+
+		$ev = new PlayerEntityPickEvent($this, $entity, $item);
+		$existingSlot = $this->inventory->first($item);
+		if($existingSlot === -1 && ($this->hasFiniteResources() || $this->isSpectator())){
+			$ev->cancel();
+		}
+		$ev->call();
+
+		if(!$ev->isCancelled()){
+			$this->equipOrAddPickedItem($existingSlot, $item);
+		}
+
+		return true;
+	}
+
+	private function equipOrAddPickedItem(int $existingSlot, Item $item) : void{
+		if($existingSlot !== -1){
+			if($existingSlot < $this->inventory->getHotbarSize()){
+				$this->inventory->setHeldItemIndex($existingSlot);
+			}else{
+				$this->inventory->swap($this->inventory->getHeldItemIndex(), $existingSlot);
+			}
+		}else{
+			$firstEmpty = $this->inventory->firstEmpty();
+			if($firstEmpty === -1){ //full inventory
+				$this->inventory->setItemInHand($item);
+			}elseif($firstEmpty < $this->inventory->getHotbarSize()){
+				$this->inventory->setItem($firstEmpty, $item);
+				$this->inventory->setHeldItemIndex($firstEmpty);
+			}else{
+				$this->inventory->swap($this->inventory->getHeldItemIndex(), $firstEmpty);
+				$this->inventory->setItemInHand($item);
+			}
+		}
+	}
+
 	/**
 	 * Performs a left-click (attack) action on the block.
 	 *