Meanderer

A micro-library for scaling CSS motion path strings ✨

Usage

// Our path string
const PATH = "M32.074 13.446s-2.706-2.965-4.158-4.349c-2.003-1.908-3.941-3.942-6.268-5.437C19.33..."
// The bounds of our path
const WIDTH = 65
const HEIGHT = 30
// Generate a responsive path
const responsivePath = new Meanderer({
  path: PATH,
  width: WIDTH,
  height: HEIGHT
})
// Generate a new scaled path when required. Here we are using ResizeObserver
// with a container that uses viewport units
const setPath = () => {
  const scaledPath = responsivePath.generatePath(
    CONTAINER.offsetWidth,
    CONTAINER.offsetHeight
  )
  // Here, we apply the path to an element through a CSS variable.
  // And then an element picks up on that. We could apply the motion path straight to the element though.
  CONTAINER.style.setProperty("--path", `"${scaledPath}"`)
}
// Set up our Resize Observer that will get the ball rolling
const SizeObserver = new ResizeObserver(setPath)
// Observe! Done!
SizeObserver.observe(CONTAINER)

First things first. We need a path. Unless you're constructing one by hand, it's likely you'll be extracting one from an SVG.

Before extracting one from an SVG, it's wise to run that SVG through an optimizer like SVGOMG(Use the precision slider for extra gains! 💪). This will normalize coordinates, etc. removing any translations which could skew the path translation.

Now you've got a path string, it's time to use it!

1. Create variables for the path, and a desired width and height for the path bounds. The width and height are in most cases going to be the x2 and y2 of your SVG's viewBox attribute.

  const PATH = "M32.074 13.446s-2.706-2.965-4.158-4.349c-2.003-1.908-3.941-3.942-6.268-5.437C19.33..."
  // The bounds of our path
  const WIDTH = 65
  const HEIGHT = 30

2. Create a new responsive path by passing those variables inside an Object to a new Meanderer instance.

  // Generate a responsive path
  const responsivePath = new Meanderer({
    path: PATH,
    width: WIDTH,
    height: HEIGHT
  })

3. Use your instance to generate scaled path strings for a given width and height 👍

  responsivePath.generatePath(200, 400)

4. Pass that to your element either directly or via CSS variable, etc. 🎉

Caveats

Meanderer will do its best to maintain aspect ratio of your paths. If the container dimensions passed in to generatePath don't match the aspect ratio of the path, Meanderer will handle this. It will do this by padding out the container and centering the path for you.

Contributing

I'd love some contributions if you think this micro-library could be useful for you! Leave an issue or open a PR 👍

Made with 💻 by @jh3y 2020