// SpryImageLoader.js - version 0.3 - Spry Pre-Release 1.7

//

// Copyright (c) 2007. Adobe Systems Incorporated.

// All rights reserved.

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are met:

//

//   * Redistributions of source code must retain the above copyright notice,

//     this list of conditions and the following disclaimer.

//   * Redistributions in binary form must reproduce the above copyright notice,

//     this list of conditions and the following disclaimer in the documentation

//     and/or other materials provided with the distribution.

//   * Neither the name of Adobe Systems Incorporated nor the names of its

//     contributors may be used to endorse or promote products derived from this

//     software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

// POSSIBILITY OF SUCH DAMAGE.



(function() { // BeginSpryComponent



if (typeof Spry == "undefined") window.Spry = {}; if (!Spry.Utils) Spry.Utils = {};



Spry.Utils.ImageLoader = function()

{

	this.queue = [];

	this.timerID = 0;

	this.currentEntry = null;

};



Spry.Utils.ImageLoader.prototype.start = function()

{

	if (!this.timerID)

	{

		var self = this;

		this.timerID = setTimeout(function()

		{

			self.timerID = 0;

			self.processQueue();

		}, 0);

	}

};



Spry.Utils.ImageLoader.prototype.stop = function()

{

	if (this.currentEntry)

	{

		var entry = this.currentEntry;

		entry.loader.onload = null;

		entry.loader.src = "";

		entry.loader = null;

		this.currentEntry = null;

		this.queue.unshift(entry);

	}



	if (this.timerID)

		clearTimeout(this.timerID);



	this.timerID = 0;

};



Spry.Utils.ImageLoader.prototype.clearQueue = function()

{

	this.stop();

	this.queue.length = 0;

};



Spry.Utils.ImageLoader.prototype.load = function(url, callback, priority)

{

	if (url)

	{

		if (typeof priority == "undefined")

			priority = 0;

		this.queue.push({ url: url, callback: callback, priority: priority });



		// Entries in the queue are sorted by priority. Those entries

		// with a higher priority are at the start of the queue, while

		// those with lower priority are pushed towards the end. If an

		// entry has the same priority as something already in the queue,

		// it gets processed in the order they were received.



		this.queue.sort(function(a,b){ return (a.priority > b.priority) ? -1 : ((a.priority < b.priority) ? 1 : 0); });

		this.start();

	}

};



Spry.Utils.ImageLoader.prototype.processQueue = function()

{

	if (this.queue.length < 1)

		return;



	var entry = this.currentEntry = this.queue.shift();

	var loader = entry.loader = new Image;

	var self = this;



	loader.onload = function()

	{

		self.currentEntry = null;

		if (entry.callback)

			entry.callback(entry.url, entry.loader);

		if (self.queue.length > 0)

			self.start();

	};



	loader.onerror = function()

	{

		// If a load fails, keep the queue going!

		self.currentEntry = null;

		if (self.queue.length > 0)

			self.start();

	};



	this.currentLoader = loader;

	loader.src = entry.url;

};



})(); // EndSpryComponent