# Hooke: figures on springs

Hooke is a Javascript library-thing that allows you to lay out figures to the side of text. This is mostly for aethetic reasons, but it also has the advantage that it makes text easier to read, since you aren’t interrupted by figures; Hooke enables a style similar to the same way research papers are laid out, with figures independent to – and referenced from – the text. The goal is to go from this:

To this:

For maximum overkill, I did this using springs (and Hooke’s law). While the transformation seems fairly simple, bringing the figures in the text out-of-line leads to overlap issues; once the anchor point of each image is fixed to its location in the text, it’s easy to imagine situations in which you could make images overlap with each other. To get around this overlap, I attach three springs to each image; one to each of its neighbors, and one to its original location. I also fix the first and last image in place. I then run a physical simulation over the spring system until the amount of potential energy present in the system reaches a certain lower threshold and is maintained at a low value through multiple timesteps. This keeps the images from laying out over each other while still keeping them as close to their starting point as possible.

This was definitely made for my writing at haldean.org, and is married to the layout of those pages (the page on sous vide is a good example). To use it, set your body’s width to a certain value less than the width of the screen. The images will be laid out in the right gutter of the window if there’s space for them; if the width of the images would be less than 300 pixels, then it keeps the images inline. This also means that pages that use Hooke still look good on phones and tablets.

Note that Hooke, by default, operates on figure tags, not img tags. This is for a couple reasons:

1. You can group images and image captions together when doing the layout pass.
2. You can specify images that should stay inline with the text (just use img instead of figure).
3. You can have other things go in the right gutter (code snippets, block quotes, you name it).

For a treat, try appending #animate to any page running Hooke, and watch the springs in action, like so. You can get Hooke from Github; it’s just one file to include in your HTML that needs JQuery to run.

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