gistfile1.coffee

# Provides functions that help with scrolling
# -----------------------------------------------------------------------------
Ok.ScrollHelpers = {
  # Check if an element has a scrollbar.
  checkScroll: (element, dir) ->
    if dir == 'horizontal'
      # Half pixels on innerWidth get rounded down. Better way to handle this?
      return element.prop('scrollWidth') > (element.innerWidth() + 1)
    else
      return element.prop('scrollHeight') > element.innerHeight()

  # Prevent body from scrolling when you reach the top / bottom of an element
  preventOverscroll: (element) ->
    if typeof element == 'string' then element = $('#' + element)
    element.on('mousewheel', (e, delta) ->
      $element = $(this)
      if ScrollHelpers.checkScroll($element)
        scrollTop = $element.scrollTop()
        # Prevent top scroll
        if delta > 0 && scrollTop == 0
          e.preventDefault()
        # Prevent bottom scroll
        else if delta < 0 && (scrollTop == $element.prop('scrollHeight') - $element.innerHeight())
          e.preventDefault()
    )

  # Simple animated scroll.
  # Position - position of where to scroll in px from top.
  # Speed - speed to scroll in ms. Blank or 0 for instant jump.
  scrollTo: (position, speed) ->
    if speed
      $('body, html, window, document').animate({
        scrollTop: position
      }, speed);
    else
      $(window).scrollTop(position)
}