Question

Does Facebook in its gallery put image width and height in database?

Using JavaScript, they can not be sure about image width and height until image fully loads. But on FB, image is been loaded while its displaying and image is properly centered horizontally and vertically.

Answer 1

Facebook use display:inline-block for the image and text-align:center for parent div to center image in theater images.
Check out their blog post that explained how they did it. It’s a nice CSS code but not all CSS. They use JS to set line-height of one of divs based on window.height.