Make default props available to users of the generated component

[chriscoomber]

Feature request

Would it be useful to export the default props of the in some way. E.g.:

<svg width="48px" height="1px" viewBox="0 0 48 1" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
    <path fill="#063855" fillRule="evenodd" d="M0 0h48v1H0z" />
</svg>

to become

import * as React from "react"
const SvgComponent = (props) => (
  <svg xmlns="http://www.w3.org/2000/svg" width={48} height={1} {...props}>
    <path fill="#063855" d="M0 0h48v1H0z" />
  </svg>
)
SvgComponent.defaults = {  // Export default props here
  width: 48,
  height: 48
}
export default SvgComponent

This doesn't change functionality at all, but allows a user of this react component to do something like:

<MyIcon width={MyIcon.defaults.width * 0.5} height={MyIcon.defaults.width * 0.5} />

Why

My use case for this is that I have several SVGs of different sizes which I would like to scale consistently together. So for example I have the following SVGs:

1. A whole pizza, divided into 8 slices
2. Left 4 slices of a pizza only (narrower than the whole pizza)
3. Top 4 slices of a pizza only (shorter than the whole pizza)

At their default dimensions, they are at the same scale, i.e. the pizza slices across all the SVGs are the same size.

I would like to display 6 of these SVGs in a row, programatically generated (this is for an elementary maths question). I want the collection of all 6 to be the largest they can be whilst fitting in a known rectangle. However, I additionally want that they all stay at the same scale as each other. This means that I can't naively share out the space evenly, since if vertical space is not a limiting factor the narrower ones will scale more.

These requirements are all easy to meet with a little bit of calculation, but that calculation requires us knowing the default dimensions of each SVG.

In my use-case, I'm actually using react-native-svg-transformer, so I don't have access to the exported react code to fiddle with it. It feels like SVGR is in the right position to add these properties.