Hotbar/inventory bugfixes (#399)

- Fixed most issues with item equipment in creative
- Added save and restore of currently-held item
- Reset hotbar on death, added API method PlayerInventory->resetHotbar()
- Creative players now have more leeway to get items, alleviates issues with item equipment in desktop GUI
- Fixed creative players wearing armour
- Found unknown field in ContainerSetSlotPacket
- Removed outdated/redundant constants
- Use a case statement in ContainerSetSlotPacket handler, added handling for 0x7a hotbar slot link update

src/pocketmine/inventory/PlayerInventory.php

@@ -40,7 +40,7 @@ class PlayerInventory extends BaseInventory{
 	protected $hotbar;
 
 	public function __construct(Human $player){
-		$this->hotbar = range(0, $this->getHotbarSize() - 1, 1);
+		$this->resetHotbar(false);
 		parent::__construct($player, InventoryType::get(InventoryType::PLAYER));
 	}
 
@@ -53,20 +53,93 @@ class PlayerInventory extends BaseInventory{
 		$this->sendContents($this->getViewers());
 	}
 
-	public function getHotbarSlotIndex($index){
-		return ($index >= 0 and $index < $this->getHotbarSize()) ? $this->hotbar[$index] : -1;
+	/**
+	 * Called when a client equips a hotbar slot. This method should not be used by plugins.
+	 * This method will call PlayerItemHeldEvent.
+	 *
+	 * @param int      $hotbarSlot Number of the hotbar slot to equip.
+	 * @param int|null $inventorySlot Inventory slot to map to the specified hotbar slot. Supply null to make no change to the link.
+	 *
+	 * @return bool if the equipment change was successful, false if not.
+	 */
+	public function equipItem(int $hotbarSlot, $inventorySlot = null) : bool{
+		if($inventorySlot === null){
+			$inventorySlot = $this->getHotbarSlotIndex($this->getHeldItemIndex());
+		}
+		if($hotbarSlot < 0 or $hotbarSlot >= $this->getHotbarSize() or $inventorySlot < -1 or $inventorySlot >= $this->getSize()){
+			$this->sendContents($this->getHolder());
+			return false;
+		}
+
+		$this->getHolder()->getLevel()->getServer()->getPluginManager()->callEvent($ev = new PlayerItemHeldEvent($this->getHolder(), $this->getItem($inventorySlot), $inventorySlot, $hotbarSlot));
+		if($ev->isCancelled()){
+			$this->sendContents($this->getHolder());
+			return false;
+		}
+
+		$this->setHotbarSlotIndex($hotbarSlot, $inventorySlot);
+		$this->setHeldItemIndex($hotbarSlot, false);
+
+		return true;
 	}
 
-	public function setHotbarSlotIndex($index, $slot){
-		if($index >= 0 and $index < $this->getHotbarSize() and $slot >= -1 and $slot < $this->getSize()){
-			$this->hotbar[$index] = $slot;
+	/**
+	 * Returns the index of the inventory slot mapped to the specified hotbar slot, or -1 if the hotbar slot does not exist.
+	 * @param int $index
+	 *
+	 * @return int
+	 */
+	public function getHotbarSlotIndex($index){
+		return $this->hotbar[$index] ?? -1;
+	}
+
+	/**
+	 * @internal This method is intended for use in network interaction with clients only.
+	 * @deprecated Do not change hotbar slot mapping with plugins, this will cause myriad client-sided bugs, especially with desktop GUI clients.
+	 *
+	 * @param int $hotbarSlot
+	 * @param int $inventorySlot
+	 */
+	public function setHotbarSlotIndex($hotbarSlot, $inventorySlot){
+		if($hotbarSlot >= 0 and $hotbarSlot < $this->getHotbarSize() and $inventorySlot >= -1 and $inventorySlot < $this->getSize()){
+			if($inventorySlot !== -1 and ($alreadyEquippedIndex = array_search($inventorySlot, $this->hotbar)) !== false){
+				/* Swap the slots
+				 * This assumes that the equipped slot can only be equipped in one other slot
+				 * it will not account for ancient bugs where the same slot ended up linked to several hotbar slots.
+				 * Such bugs will require a hotbar reset to default.
+				 */
+				$this->hotbar[$alreadyEquippedIndex] = $this->hotbar[$hotbarSlot];
+			}
+			$this->hotbar[$hotbarSlot] = $inventorySlot;
 		}
 	}
 
+	/**
+	 * Resets hotbar links to their original defaults.
+	 * @param bool $send Whether to send changes to the holder.
+	 */
+	public function resetHotbar(bool $send = true){
+		$this->hotbar = range(0, $this->getHotbarSize() - 1, 1);
+		if($send){
+			$this->sendContents($this->getHolder());
+		}
+	}
+
+	/**
+	 * Returns the hotbar slot number the holder is currently holding.
+	 * @return int
+	 */
 	public function getHeldItemIndex(){
 		return $this->itemInHandIndex;
 	}
 
+	/**
+	 * Sets which hotbar slot the player is currently loading.
+	 *
+	 * @param int  $index 0-8 index of the hotbar slot to hold
+	 * @param bool $send  Whether to send updates back to the inventory holder. This should usually be true for plugin calls.
+	 *                    It should only be false to prevent feedback loops of equipment packets between client and server.
+	 */
 	public function setHeldItemIndex($index, $send = true){
 		if($index >= 0 and $index < $this->getHotbarSize()){
 			$this->itemInHandIndex = $index;
@@ -79,6 +152,11 @@ class PlayerInventory extends BaseInventory{
 		}
 	}
 
+	/**
+	 * Returns the currently-held item.
+	 *
+	 * @return Item
+	 */
 	public function getItemInHand(){
 		$item = $this->getItem($this->getHeldItemSlot());
 		if($item instanceof Item){
@@ -89,6 +167,7 @@ class PlayerInventory extends BaseInventory{
 	}
 
 	/**
+	 * Sets the item in the currently-held slot to the specified item.
 	 * @param Item $item
 	 *
 	 * @return bool
@@ -97,29 +176,29 @@ class PlayerInventory extends BaseInventory{
 		return $this->setItem($this->getHeldItemSlot(), $item);
 	}
 
+	/**
+	 * Returns the hotbar slot number currently held.
+	 *
+	 * @return int
+	 */
 	public function getHeldItemSlot(){
 		return $this->getHotbarSlotIndex($this->itemInHandIndex);
 	}
 
+	/**
+	 * Sets the hotbar slot link of the currently-held hotbar slot.
+	 * @deprecated Do not change hotbar slot mapping with plugins, this will cause myriad client-sided bugs, especially with desktop GUI clients.
+	 *
+	 * @param int $slot
+	 */
 	public function setHeldItemSlot($slot){
 		if($slot >= -1 and $slot < $this->getSize()){
-			$item = $this->getItem($slot);
-
-			$itemIndex = $this->getHeldItemIndex();
-
-			if($this->getHolder() instanceof Player){
-				Server::getInstance()->getPluginManager()->callEvent($ev = new PlayerItemHeldEvent($this->getHolder(), $item, $slot, $itemIndex));
-				if($ev->isCancelled()){
-					$this->sendContents($this->getHolder());
-					return;
-				}
-			}
-
-			$this->setHotbarSlotIndex($itemIndex, $slot);
+			$this->setHotbarSlotIndex($this->getHeldItemIndex(), $slot);
 		}
 	}
 
 	/**
+	 * Sends the currently-held item to specified targets.
 	 * @param Player|Player[] $target
 	 */
 	public function sendHeldItem($target){
@@ -128,8 +207,8 @@ class PlayerInventory extends BaseInventory{
 		$pk = new MobEquipmentPacket();
 		$pk->eid = $this->getHolder()->getId();
 		$pk->item = $item;
-		$pk->slot = $this->getHeldItemSlot();
-		$pk->selectedSlot = $this->getHeldItemIndex();
+		$pk->inventorySlot = $this->getHeldItemSlot();
+		$pk->hotbarSlot = $this->getHeldItemIndex();
 
 		if(!is_array($target)){
 			$target->dataPacket($pk);
@@ -161,6 +240,10 @@ class PlayerInventory extends BaseInventory{
 		}
 	}
 
+	/**
+	 * Returns the number of slots in the hotbar.
+	 * @return int
+	 */
 	public function getHotbarSize(){
 		return 9;
 	}

src/pocketmine/inventory/SimpleTransactionGroup.php

@@ -130,7 +130,21 @@ class SimpleTransactionGroup implements TransactionGroup{
 		$haveItems = [];
 		$needItems = [];
 
-		return $this->matchItems($haveItems, $needItems) and count($haveItems) === 0 and count($needItems) === 0 and count($this->transactions) > 0;
+		if($this->matchItems($needItems, $haveItems) and count($this->transactions) > 0){
+			if(count($haveItems) === 0 and count($needItems) === 0){
+				return true;
+			}elseif($this->source->isCreative(true) and count($needItems) > 0){ //Added items from creative inventory
+				foreach($needItems as $item){
+					if(Item::getCreativeItemIndex($item) === -1 and $item->getId() !== Item::AIR){
+						return false;
+					}
+				}
+
+				return true;
+			}
+		}
+
+		return false;
 	}
 
 	public function execute(){