Allow for parent element point of reference for parallax-background instead of only window.

[websirnik]

I need to enable parallax for a parent div with overflow:scroll. Is that what you've meant here? Is there a way to hack it atm?

Yes, that was my plan. Currently, I'm calculating directly off of the window element through Angular's $window service.

var calcValY = (elem.prop('offsetTop') - $window.pageYOffset) * ($scope.parallaxRatio ? $scope.parallaxRatio : 1.1 );

I don't see it being overly difficult to modify the directive to allow for a parent element in addition to $window, but haven't taken a stab at it yet myself.

Off the top of my head, I can't think of a way to hack it in.