/*

 *

 * Detect Image Support

 * Requires latest jQuery (jquery.com)

 *

 * By Jean-Luc Thiebaut (airlock.com)

 * 2007-09-28

 *

 * Update Sim Hoang (airlock.com)

 * 2008-05-20

 *

 */



 

// set globals

var css_path = "/radio3/freethinking/2008/assets/css/image-replacement.css";

var image_path = "/radio3/freethinking/2008/assets/ui/image-detect.gif";

var test_image_id = "detect-image-test";

var fallback_timeout = 5000;

var cookie_expire = 1200000; // 20 mins



function detect_image_support() {

	

	// create a test image

	var image = new Image();

	image.src = image_path+"?"+get_random();

	image.id = test_image_id;

	

	

	// Gecko-based / Safari executes next line when images are NOT supported

	if(image.complete) {

	

		$("body")

			.removeClass("checking-image-support")

			.addClass("no-image-support");

			

		create_cookie('image_support','false',cookie_expire);

				

		return;

	}



	

	setInterval(function() {

		var bc = $("body").attr("class");

		//alert("on interval BODY CLASS = "+ bc);

	}, 5000);

	

	// otherwise continue and set image onload

	image.onload = function() {

	

		

		var bc = $("body").attr("class");

		//alert("on image load body = " + bc + " & cookie = " + read_cookie("image_support"));

			

		// fixes IE issue after reactivating images, will default back to no-image-support mode for first refresh

		if($.browser.msie && read_cookie("image_support") == "false" && bc.indexOf("no-image-support") != -1) {

			erase_cookie('image_support');

			return;

		}

		

		create_cookie('image_support','true',cookie_expire);

		

		// assign image-support class

		$("body")

			.addClass("image-support")

			.removeClass("checking-image-support")

			.removeClass("no-image-support");

		

		// clear the interval 

		clearInterval(image_detect_interval);

		

	}



	

	// 

	if(!read_cookie("image_support") || read_cookie("image_support") == "true") {

		var image_detect_interval = setInterval("flag_image_support()", fallback_timeout);

	

	// else call fallback function immediately

	} else if (read_cookie("image_support") == "false") {

		

		flag_image_support();



	} 





}



// in the absence of image.onFail create a fallback timeout to revert to no-image-support

function flag_image_support() {

	

	var bc = $("body").attr("class");

		

	// if image support isn't flagged OR is the script is still checking

	if(bc.indexOf("image-support") == -1 || bc.indexOf("checking-image-support") != -1) {

		

		// assign no-image-support class

		$("body")

			.removeClass("checking-image-support")

			.removeClass("image-support")

			.addClass("no-image-support");

			

		create_cookie('image_support','false',cookie_expire);

		

	}

	

}





// create a random number

function get_random() {

    var ranNum= Math.floor(Math.random()*100000000);

    return ranNum;

}





// create cookie

function create_cookie(name,value,seconds) {

	if (seconds) {

		var date = new Date();

		date.setTime(date.getTime()+(seconds));

		var expires = "; expires="+date.toGMTString();

	}

	else var expires = "";

	document.cookie = name+"="+value+expires+"; path=/radio3/freethinking/";

}





// read cookie

function read_cookie(name) {

	var nameEQ = name + "=";

	var ca = document.cookie.split(';');

	for(var i=0;i < ca.length;i++) {

		var c = ca[i];

		while (c.charAt(0)==' ') c = c.substring(1,c.length);

		if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);

	}

	return null;

}



// erase cookie

function erase_cookie(name) {

	create_cookie(name,"",-1);

}



// attach style sheet to the head of document; only executed by JS enabled browsers

var headID = document.getElementsByTagName("head")[0];

var cssNode = document.createElement('link');

cssNode.type = 'text/css';

cssNode.rel = 'stylesheet';

cssNode.href = css_path;

cssNode.media = 'screen';

headID.appendChild(cssNode);





jQuery(document).ready(function() {

	

	// initialise image support detection

	detect_image_support();

	

});