12 images in a grid. Random order and given size

I'm making a image grid of 12 images of 3 given sizes.

• 1080x320


• 720x320


• 320x320

Basic view of the grid can be seen in the following illustration: http://ift.tt/1IYtpQz

I want the layout to be able to change it's pattern, like the second image.

But also making the images change position and size, like the third image in the gallery.

• All of the 12 images must be shown.


• The layout can be changed, ex. 12 1080x320 boxes or 12 320x320 boxes or 6 720x320 and 6 320x320 boxes

I've been searching Google, but can't find a Wordpress plugin or jQuery plugin that fit my needs. Do you have some ideas to my problem? Ideas of solutions and so on. All tips are very much welcome.