some cleanup to held item handling

src/pocketmine/inventory/PlayerInventory.php

@@ -25,11 +25,7 @@ namespace pocketmine\inventory;
 
 use pocketmine\entity\Human;
 use pocketmine\item\Item;
-use pocketmine\network\mcpe\protocol\MobEquipmentPacket;
-use pocketmine\network\mcpe\protocol\types\ContainerIds;
 use pocketmine\player\Player;
-use function in_array;
-use function is_array;
 
 class PlayerInventory extends BaseInventory{
 
@@ -98,11 +94,12 @@ class PlayerInventory extends BaseInventory{
 
 		$this->itemInHandIndex = $hotbarSlot;
 
-		if($this->getHolder() instanceof Player and $send){
+		if($this->holder instanceof Player and $send){
-			$this->sendHeldItem($this->getHolder());
+			$this->holder->getNetworkSession()->getInvManager()->syncSelectedHotbarSlot();
+		}
+		foreach($this->holder->getViewers() as $viewer){
+			$viewer->getNetworkSession()->onMobEquipmentChange($this->holder);
 		}
-
-		$this->sendHeldItem($this->getHolder()->getViewers());
 	}
 
 	/**
@@ -121,29 +118,8 @@ class PlayerInventory extends BaseInventory{
 	 */
 	public function setItemInHand(Item $item) : void{
 		$this->setItem($this->getHeldItemIndex(), $item);
-		$this->sendHeldItem($this->holder->getViewers());
+		foreach($this->holder->getViewers() as $viewer){
-	}
+			$viewer->getNetworkSession()->onMobEquipmentChange($this->holder);
-
-	/**
-	 * Sends the currently-held item to specified targets.
-	 *
-	 * @param Player|Player[] $target
-	 */
-	public function sendHeldItem($target) : void{
-		$item = $this->getItemInHand();
-
-		$pk = MobEquipmentPacket::create($this->getHolder()->getId(), $item, $this->getHeldItemIndex(), ContainerIds::INVENTORY);
-
-		if(!is_array($target)){
-			$target->sendDataPacket($pk);
-			if($target === $this->getHolder()){
-				$target->getNetworkSession()->getInvManager()->syncSlot($this, $this->getHeldItemIndex());
-			}
-		}else{
-			$this->getHolder()->getWorld()->getServer()->broadcastPacket($target, $pk);
-			if(in_array($this->getHolder(), $target, true)){
-				$target->getNetworkSession()->getInvManager()->syncSlot($this, $this->getHeldItemIndex());
-			}
 		}
 	}
 

src/pocketmine/network/mcpe/InventoryManager.php

@@ -36,6 +36,7 @@ use pocketmine\network\mcpe\protocol\ContainerOpenPacket;
 use pocketmine\network\mcpe\protocol\ContainerSetDataPacket;
 use pocketmine\network\mcpe\protocol\InventoryContentPacket;
 use pocketmine\network\mcpe\protocol\InventorySlotPacket;
+use pocketmine\network\mcpe\protocol\PlayerHotbarPacket;
 use pocketmine\network\mcpe\protocol\types\ContainerIds;
 use pocketmine\network\mcpe\protocol\types\WindowTypes;
 use pocketmine\player\Player;
@@ -144,6 +145,10 @@ class InventoryManager{
 		}
 	}
 
+	public function syncSelectedHotbarSlot() : void{
+		$this->session->sendDataPacket(PlayerHotbarPacket::create($this->player->getInventory()->getHeldItemIndex(), ContainerIds::INVENTORY));
+	}
+
 	public function syncCreative() : void{
 		$items = [];
 		if(!$this->player->isSpectator()){ //fill it for all gamemodes except spectator

src/pocketmine/network/mcpe/NetworkSession.php

@@ -24,6 +24,7 @@ declare(strict_types=1);
 namespace pocketmine\network\mcpe;
 
 use pocketmine\entity\effect\EffectInstance;
+use pocketmine\entity\Human;
 use pocketmine\entity\Living;
 use pocketmine\event\player\PlayerCreationEvent;
 use pocketmine\event\server\DataPacketReceiveEvent;
@@ -47,6 +48,7 @@ use pocketmine\network\mcpe\protocol\DisconnectPacket;
 use pocketmine\network\mcpe\protocol\GarbageServerboundPacket;
 use pocketmine\network\mcpe\protocol\MobArmorEquipmentPacket;
 use pocketmine\network\mcpe\protocol\MobEffectPacket;
+use pocketmine\network\mcpe\protocol\MobEquipmentPacket;
 use pocketmine\network\mcpe\protocol\ModalFormRequestPacket;
 use pocketmine\network\mcpe\protocol\MovePlayerPacket;
 use pocketmine\network\mcpe\protocol\NetworkChunkPublisherUpdatePacket;
@@ -62,6 +64,7 @@ use pocketmine\network\mcpe\protocol\TransferPacket;
 use pocketmine\network\mcpe\protocol\types\CommandData;
 use pocketmine\network\mcpe\protocol\types\CommandEnum;
 use pocketmine\network\mcpe\protocol\types\CommandParameter;
+use pocketmine\network\mcpe\protocol\types\ContainerIds;
 use pocketmine\network\mcpe\protocol\types\PlayerListEntry;
 use pocketmine\network\mcpe\protocol\types\PlayerPermissions;
 use pocketmine\network\mcpe\protocol\UpdateAttributesPacket;
@@ -776,6 +779,18 @@ class NetworkSession{
 		return $this->invManager;
 	}
 
+	/**
+	 * TODO: expand this to more than just humans
+	 * TODO: offhand
+	 *
+	 * @param Human $mob
+	 */
+	public function onMobEquipmentChange(Human $mob) : void{
+		//TODO: we could send zero for slot here because remote players don't need to know which slot was selected
+		$inv = $mob->getInventory();
+		$this->sendDataPacket(MobEquipmentPacket::create($mob->getId(), $inv->getItemInHand(), $inv->getHeldItemIndex(), ContainerIds::INVENTORY));
+	}
+
 	public function onMobArmorChange(Living $mob) : void{
 		$inv = $mob->getArmorInventory();
 		$this->sendDataPacket(MobArmorEquipmentPacket::create($mob->getId(), $inv->getHelmet(), $inv->getChestplate(), $inv->getLeggings(), $inv->getBoots()));

src/pocketmine/network/mcpe/handler/InGamePacketHandler.php

@@ -359,7 +359,7 @@ class InGamePacketHandler extends PacketHandler{
 
 	public function handleMobEquipment(MobEquipmentPacket $packet) : bool{
 		if(!$this->player->selectHotbarSlot($packet->hotbarSlot)){
-			$this->player->getInventory()->sendHeldItem($this->player);
+			$this->session->getInvManager()->syncSelectedHotbarSlot();
 		}
 		return true;
 	}

src/pocketmine/network/mcpe/handler/PreSpawnPacketHandler.php

@@ -93,7 +93,7 @@ class PreSpawnPacketHandler extends PacketHandler{
 
 		$this->session->getInvManager()->syncAll();
 		$this->session->getInvManager()->syncCreative();
-		$this->player->getInventory()->sendHeldItem($this->player);
+		$this->session->getInvManager()->syncSelectedHotbarSlot();
 		$this->session->queueCompressed($this->server->getCraftingManager()->getCraftingDataPacket());
 
 		$this->session->syncPlayerList();

src/pocketmine/network/mcpe/protocol/PlayerHotbarPacket.php

@@ -28,9 +28,6 @@ namespace pocketmine\network\mcpe\protocol;
 use pocketmine\network\mcpe\handler\PacketHandler;
 use pocketmine\network\mcpe\protocol\types\ContainerIds;
 
-/**
- * One of the most useless packets.
- */
 class PlayerHotbarPacket extends DataPacket implements ClientboundPacket, ServerboundPacket{
 	public const NETWORK_ID = ProtocolInfo::PLAYER_HOTBAR_PACKET;
 
@@ -41,6 +38,14 @@ class PlayerHotbarPacket extends DataPacket implements ClientboundPacket, Server
 	/** @var bool */
 	public $selectHotbarSlot = true;
 
+	public static function create(int $slot, int $windowId, bool $selectSlot = true) : self{
+		$result = new self;
+		$result->selectedHotbarSlot = $slot;
+		$result->windowId = $windowId;
+		$result->selectHotbarSlot = $selectSlot;
+		return $result;
+	}
+
 	protected function decodePayload() : void{
 		$this->selectedHotbarSlot = $this->getUnsignedVarInt();
 		$this->windowId = $this->getByte();