var xPos = 300;
var yPos = 200;
var step = 1;
var delay = 30;
var height = 0;
var Hoffset = 0;
var Woffset = 0;
var yon = 0;
var xon = 0;
var pause = true;
var interval;
var img1=$('.welc-pop-box');
img1.css({
	top: yPos
});

function changePos() {
	width = $(window).width();
	height = $(window).height();
	Hoffset = img1.width();
	Woffset = img1.height();
	img1.css({
		top: yPos + $(document).scrollTop(),
		left: xPos + $(document).scrollLeft()
	});
	if (yon) {
		yPos = yPos + step;
	} else {
		yPos = yPos - step;
	}
	if (yPos < 0) {
		yon = 1;
		yPos = 0;
	}
	if (yPos >= (height - Hoffset)) {
		yon = 0;
		yPos = (height - Hoffset);
	}
	if (xon) {
		xPos = xPos + step;
	} else {
		xPos = xPos - step;
	}
	if (xPos < 0) {
		xon = 1;
		xPos = 0;
	}
	if (xPos >= (width - Woffset)) {
		xon = 0;
		xPos = (width - Woffset);
	}
}
function start() {
	img1.css({
		visibility: 'visible'
	});
	interval = setInterval('changePos()', delay);
}
function pause_resume() {
	if (pause) {
		clearInterval(interval);
		pause = false;
	} else {
		interval = setInterval('changePos()', delay);
		pause = true;
	}
}
img1.hover(function(){
	pause_resume();
},function(){
	pause_resume();
});

start();