Do not dispatch display events for elements hidden with styles

[michael-parkins]

🚀 Feature request

Please describe what is needed
Currently the oculrDisplay directive will dispatch display events as long as Angular builds the element in the DOM. Elements that do not render visually on the screen due to styles are still in the DOM and will still dispatch a display event even though the user didn't see the element.

Describe the solution you'd like

• Check if element is visible based on styles. There are many way to hide an element, we should limit this check to the following commonly used solutions:
  • display: none
  • opactity: 0
  • visibility: hidden
• Bind to style changes to determine if element is going from hidden to visible state

Describe alternatives you've considered
The lib currently allows a manual display dispatch using services. This isn't optimal, but still works. Since there are many ways to hide elements, its possible an incomplete enhancement will make the API more cumbersome with little gain.