How to add image-loading indicator in product info page?

Hi, good afternoon!

I want to add "Progress Bar" for loading medium image in product info page, how can I implement this function?

Add a loading picture while the medium image of the product is loading?

Do you have any advice? Please give me some help, thank you in advance!

If your images (medium or otherwise) are taking so long to download, then your customers are probably not going to wait around to watch a progress bar as they click to visit products. If I was on your site and every product I click on has progress bars... guess what? ... I'm outa there!

Optimize your image files - each product pic should be no more than 75 - 100 kb, and consider using Image Handler as this will both optimize images and improve visual quality.

@schoolboy: Thanks for your reply, I agree it.

The size of each medium product pic is smaller than 100kb, if the network is slow, the pic'll be displayed very slow.

The most important is that it's boss's opinion:D

Expect more of your advice, thank you in advance!