zoom in, zoom out in as3

var count_zoom:Number = 0;

zoomInButton.addEventListener(MouseEvent.MOUSE_DOWN, zoomIn);
zoomOutButton.addEventListener(MouseEvent.MOUSE_DOWN, zoomOut);
function zoomIn(e:MouseEvent)
{
    bg.scaleX +=  .1;
    bg.scaleY +=  .1;
    count_zoom++;

}
function zoomOut(e:MouseEvent)
{
    bg.scaleX -=  .1;
    bg.scaleY -=  .1;
    count_zoom--;

}


stage.addEventListener(Event.ENTER_FRAME, loop);
function loop(e:Event)
{
    if (count_zoom == 0)
    {
        trace("0");
        zoomOutButton.visible = false;
    }
    if (count_zoom == 5)
    {
        trace("5");
        zoomInButton.visible = false;
    }
    if (count_zoom >= 1 && count_zoom <= 4)
    {
        trace("1,2,3,4");
        zoomInButton.visible = true;
        zoomOutButton.visible = true;
    }
}

1. Create movieclips instance name of bg, zoomInButton, zoomOutButton

Out put :-