/* content_scroll.js */
/* content scrolling javascript */

// scroll the content on-screen
function ScrollDivContent(scrollDiv, scrollBar, scrollBarHandle)
{		
	// create a new scriptaculous slider control
	var contentSlider = new Control.Slider(scrollBarHandle, scrollBar, {
					axis: 'vertical',
					onSlide: function(v) { scrollVertical(v, $(scrollDiv), contentSlider);  },
					onChange: function(v) { scrollVertical(v, $(scrollDiv), contentSlider); }
				 	});

	// disable vertical scrolling if text doesn't overflow the div
	if ( $(scrollDiv).scrollHeight <= $(scrollDiv).offsetHeight ) 
	{
		contentSlider.setDisabled();
		$(scrollBar).hide();
	}
	// otherwise if it doesn't - show the div..
	else
	{
		$(scrollBar).hide();
		$(scrollBar).style.visibility = 'visible';
		new Effect.Appear( $(scrollBar) );
	}
}

// scroll the element vertically based on its width and the slider maximum value
function scrollVertical(value, element, slider) 
{
	element.scrollTop = Math.round(value/slider.maximum*(element.scrollHeight-element.offsetHeight));
}