Many many changes related to inventory transactions, fixed item dropping, fixed creative menu

src/pocketmine/inventory/transaction/action/CreativeInventoryAction.php

@@ -0,0 +1,85 @@
+<?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\inventory\transaction\action;
+
+use pocketmine\item\Item;
+use pocketmine\Player;
+
+class CreativeInventoryAction extends InventoryAction{
+
+	/**
+	 * Player put an item into the creative window to destroy it.
+	 */
+	const TYPE_DELETE_ITEM = 0;
+	/**
+	 * Player took an item from the creative window.
+	 */
+	const TYPE_CREATE_ITEM = 1;
+
+	protected $actionType;
+
+	public function __construct(Item $sourceItem, Item $targetItem, int $actionType){
+		parent::__construct($sourceItem, $targetItem);
+		$this->actionType = $actionType;
+	}
+
+	/**
+	 * Checks that the player is in creative, and (if creating an item) that the item exists in the creative inventory.
+	 *
+	 * @param Player $source
+	 *
+	 * @return bool
+	 */
+	public function isValid(Player $source) : bool{
+		return $source->isCreative(true) and
+			($this->actionType === self::TYPE_DELETE_ITEM or Item::getCreativeItemIndex($this->sourceItem) !== -1);
+	}
+
+	/**
+	 * Returns the type of the action.
+	 */
+	public function getActionType() : int{
+		return $this->actionType;
+	}
+
+	/**
+	 * No need to do anything extra here: this type just provides a place for items to disappear or appear from.
+	 *
+	 * @param Player $source
+	 *
+	 * @return bool
+	 */
+	public function execute(Player $source) : bool{
+		return true;
+	}
+
+	public function onExecuteSuccess(Player $source){
+
+	}
+
+	public function onExecuteFail(Player $source){
+
+	}
+
+}