function next_page() {
	o = document.getElementById('next');
	window.location.href =o.href;
}


function prev_page() {
	o = document.getElementById('prev');
	window.location.href =o.href;
}


function keyup(evt) {
	evt = evt || window.event;
	var keyCode = evt.keyCode ? evt.keyCode : evt.which ? evt.which : evt.charCode;

	if (keyCode == 17) {	//Press Ctrl
		next_page();
	}
	if (keyCode == 16) {	//Press Shift
		prev_page();
	}
}


function initImg(){
viewimg.onmousedown = engage;
viewimg.onmousemove = dragIt;
viewimg.onmouseup = release;
viewimg.onmouseout = release;
viewimg.style.cursor = handICON;
} 

var movICON, handICON, status, oX, oY, cX, cY, mX, mY;
status = 0;
cX = 0;
cY = 0;

movICON = "move";
handICON = "hand";

function dragIt(){
	if (status == 1){
		mX = window.event.screenX + cX;
		mY = window.event.screenY + cY;
		window.scrollTo(oX - mX, oY - mY);
	}
	return false;
}

function engage(){
	chgCursor(2);
	status = 1;
	oX = 2 * document.documentElement.scrollLeft;
	cX = document.documentElement.scrollLeft - window.event.screenX;
	oY = 2 * document.documentElement.scrollTop;
	cY = document.documentElement.scrollTop - window.event.screenY;		
	return false;
}

function release(){
chgCursor(1);
status = 0;
return false;
}

function chgCursor(url){
switch (url){
case 1:  
{  
viewimg.style.cursor = handICON;
break;
}
case 2:
{
viewimg.style.cursor = movICON;
break;
}
default :
{
viewimg.style.cursor = handICON;
break;
}
}
}
//图片移动