var arrayPageSize;
var scrollOffset;

function hideElement(elementId) {
	$(elementId).style.visibility = 'hidden';
}

function showElement(elementId) {
	$(elementId).style.visibility = 'visible';
}

function updatePageSize() {
	arrayPageSize = getPageSize();
}

function updateScrollOffset() {
	scrollOffset = getScrollXY();
}

function showTransBG() {
	updatePageSize();
	var x	= arrayPageSize[0];
	var y	= arrayPageSize[1];
	$('TransBG').style.width = x + 'px';
	$('TransBG').style.height = y + 'px';
	centerElementInWindow(32,32,'image_loading');
	$('content').style.overflow = 'hidden';
	showElement('TransBG');
}

function hideTransBG() {
	hideElement('TransBG');
	$('content').style.overflow = 'auto';
}

function centerElementInWindow(width, height, elementId) {
	updatePageSize();
	updateScrollOffset();
	var x	= arrayPageSize[2];
	var y	= arrayPageSize[3];
	$(elementId).style.right = ((x - width) / 2 ) + scrollOffset[0] +'px';
	$(elementId).style.top = ((y - height) / 2 ) + scrollOffset[1] +'px';
}

//thank you quirksmode.org & thank you pHaez for the Firefox Edit ~DW
function getPageSize(){
	
	var xScroll, yScroll;
	
	if (window.innerHeight && window.scrollMaxY) {	
		xScroll = document.body.scrollWidth;
		yScroll = window.innerHeight + window.scrollMaxY;
	} else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
		xScroll = document.body.scrollWidth;
		yScroll = document.body.scrollHeight;
	} else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
		xScroll = document.body.offsetWidth;
		yScroll = document.body.offsetHeight;
	}
	
	var windowWidth, windowHeight;
	if (self.innerHeight) {	// all except Explorer
		windowWidth = self.innerWidth;
		windowHeight = self.innerHeight;
	} else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
		windowWidth = document.documentElement.clientWidth;
		windowHeight = document.documentElement.clientHeight;
	} else if (document.body) { // other Explorers
		windowWidth = document.body.clientWidth;
		windowHeight = document.body.clientHeight;
	}
	
	// for small pages with total height less then height of the viewport
	if(yScroll < windowHeight){
		pageHeight = windowHeight;
	} else {
		pageHeight = yScroll;
	}
	
	// for small pages with total width less then width of the viewport
	if(xScroll < windowWidth){	
		pageWidth = windowWidth;
	} else {
		pageWidth = xScroll;
	}
	arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight) 
	return arrayPageSize;
}

function getScrollXY() {
  var scrOfX = 0, scrOfY = 0;
  if( typeof( window.pageYOffset ) == 'number' ) {
    //Netscape compliant
    scrOfY = window.pageYOffset;
    scrOfX = window.pageXOffset;
  } else if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) ) {
    //DOM compliant
    scrOfY = document.body.scrollTop;
    scrOfX = document.body.scrollLeft;
  } else if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) ) {
    //IE6 standards compliant mode
    scrOfY = document.documentElement.scrollTop;
    scrOfX = document.documentElement.scrollLeft;
  }
  return [ scrOfX, scrOfY ];
}