var actT = 15;					//スクロールスピード：小＝速い

var TimeID;
var scrx,dx,x,inix,viewx;

function Init(){
	dx = 0;
	x = 0;
	inix = 0;
	viewx = inix;
}

function right(rq){
	scrx = rq;
	inix = viewx;
	dx = 0;
	x = 0;
	scroll_right();
}

function left(rq){
	scrx = rq;
	inix = viewx;
	dx = 0;
	x = 0;
	scroll_left();
}

function scroll_right(){
	var tgtx = inix + scrx;
	if( x < (scrx/2) ){
		dx++;
	}else if( x > (scrx/2) ){
		dx--;
		dx = Math.max(dx , 1);
	}
	x += dx;
	viewx = inix + x;
	viewx = Math.min( viewx , tgtx );
	self.scroll(viewx,0);
	if(viewx >= tgtx){
		clearTimeout(TimeID);
	}else{
		TimeID = setTimeout( "scroll_right()" , actT);
	}
}

function scroll_left(){
	var tgtx = inix - scrx;
	if( x < (scrx/2) ){
		dx++;
	}else if( x > (scrx/2) ){
		dx--;
		dx = Math.max(dx , 1);
	}
	x += dx;
	viewx = inix - x;
	viewx = Math.max( viewx , tgtx );
	self.scroll(viewx,0);
	if(viewx <= tgtx){
		clearTimeout(TimeID);
	}else{
		TimeID = setTimeout( "scroll_left()" , actT);
	}
}