var img_obj;
var orig_width;
var orig_height;
var resize_flag = false;

function onload_resize(image_id)
{
	var height = 0;
	var width = 0;
	img_obj = document.getElementById(image_id);
	orig_width = img_obj.width;
	orig_height = img_obj.height;
	var ratio = orig_width/orig_height;
	width = (window.innerWidth ? window.innerWidth : (document.documentElement.clientWidth ? document.documentElement.clientWidth : document.body.offsetWidth)); 
    height = (window.innerHeight ? window.innerHeight : (document.documentElement.clientHeight ? document.documentElement.clientHeight : document.body.offsetHeight)); 
	width = width - 100;
	height = height - 300;
	if (img_obj.height > height) {
		img_obj.height = height;
		img_obj.width = height * ratio;
		resize_flag = true;
	}
	else if (img_obj.width > width) {
		img_obj.width = width;
		img_obj.height = width / ratio;
		resize_flag = true;
	}
}

function onclick_resize(image_id)
{
	if (!img_obj) {img_obj = document.getElementById(image_id);}
	if (resize_flag) {
		img_obj.width = orig_width;
		img_obj.height = orig_height;
		resize_flag = false; 
	}
	else {onload_resize(image_id);}
}