paper.js/src/core/PaperScopeItem.js

/*
 * Paper.js
 *
 * This file is part of Paper.js, a JavaScript Vector Graphics Library,
 * based on Scriptographer.org and designed to be largely API compatible.
 * http://paperjs.org/
 * http://scriptographer.org/
 *
 * Copyright (c) 2011, Juerg Lehni & Jonathan Puckey
 * http://lehni.org/ & http://jonathanpuckey.com/
 *
 * Distributed under the MIT license. See LICENSE file for details.
 *
 * All rights reserved.
 */

/**
 * @name PaperScopeItem
 *
 * @class A private base class for all classes that have lists and references in
 * the {@link PaperScope} ({@link Project}, {@link View}, {@link Tool}), so
 * functionality can be shared.
 *
 * @private
 */
var PaperScopeItem = Base.extend(/** @lends PaperScopeItem# */{

	/**
	 * Creates a PaperScopeItem object.
	 */  
	initialize: function(activate) {
		// Store reference to the currently active global paper scope:
		this._scope = paper;
		// Push it onto this._scope.projects and set index:
		this._index = this._scope[this._list].push(this) - 1;
		// If the project has no active reference, activate this one
		if (activate || !this._scope[this._reference])
			this.activate();
	},

	activate: function() {
		if (!this._scope)
			return false;
		this._scope[this._reference] = this;
		return true;
	},

	isActive: function() {
		return this._scope[this._reference] === this;
	},

	remove: function() {
		if (this._index == null)
			return false;
		Base.splice(this._scope[this._list], null, this._index, 1);
		// Clear the active tool reference if it was pointint to this.
		if (this._scope[this._reference] == this)
			this._scope[this._reference] = null;
		this._scope = null;
		return true;
	}
});