_setViewportEntered(context=null) {
  Ember.assert('You must pass a valid context to _setViewportEntered', context);

  const $viewportCachedEl = get(this, '$viewportCachedEl');
  const viewportUseRAF    = get(this, 'viewportUseRAF');
  const elementId         = get(this, 'elementId');
  const tolerance         = get(this, 'viewportTolerance');
  const height            = $(context) ? $(context).height() : 0;
  const width             = $(context) ? $(context).width()  : 0;

  let boundingClientRect;

  if ($viewportCachedEl) {
    boundingClientRect = $viewportCachedEl[0].getBoundingClientRect();
  } else {
    boundingClientRect = set(this, '$viewportCachedEl', this.$())[0].getBoundingClientRect();
  }

  const viewportEntered = isInViewport(boundingClientRect, height, width, tolerance);

  set(this, 'viewportEntered', viewportEntered);

  if ($viewportCachedEl && viewportUseRAF) {
    rAFIDS[elementId] = window.requestAnimationFrame(
      bind(this, this._setViewportEntered, context)
    );
  }
},