Text `bbox` is empty when using font-size with units

[cornwe19]

It seems that when <text> or <tspan> elements have a font-size which includes a unit, this library renders their .bbox() as an empty rect (all 0's). The following example illustrates my point.

const {SVG, registerWindow} = require("@svgdotjs/svg.js")
const {createSVGWindow} = require("svgdom")

const window = createSVGWindow()
registerWindow(window, window.document)

const svg = SVG().svg(`
  <text id="unitless" font-size="20">Test</text>
  <text id="px" font-size="20px">Test</text>
`)

console.log("unitless:", svg.findOne("#unitless").bbox())
console.log("px:", svg.findOne("#px").bbox())

Which outputs the following when run in node:

unitless: Box {
  x: 0,
  y: -21.376953125,
  w: 38.88671875,
  width: 38.88671875,
  h: 27.236328125,
  height: 27.236328125,
  x2: 38.88671875,
  y2: 5.859375,
  cx: 19.443359375,
  cy: -7.7587890625
}
px: Box {
  x: 0,
  y: 0,
  w: 0,
  width: 0,
  h: 0,
  height: 0,
  x2: 0,
  y2: 0,
  cx: 0,
  cy: 0
}

[Fuzzyma]

Units are rarely used in svg. whats your usecase?

[cornwe19]

I'm importing and manipulating preexisting SVGs that happen to use units for their font-sizes.

A small step in the right direction might be to at least warn or document somewhere that measurements with units aren't supported or something. It took me a while to figure out why my text fields just weren't measuring at all.

[Fuzzyma]

Or we could just skip the unit alltogether. Feel free to implement a PR. You should find the corresponding code somewhere in https://github.com/svgdotjs/svgdom/blob/master/src/utils/textUtils.js

[cornwe19]

I think ignoring the unit would work for the case of px, but other units mean different things than the scalar values represent. I'll see if I can get a coherent PR together on this. Thanks for pointing me in the right direction in the codebase.

[Fuzzyma]

This library has no notion of real-world measurements. How much is a cm in px if you don't have a screen? There is no way to know. The only other unit that would make sense is percentage but in the end, this is a custom library that supports as much as it can. What works works and when somebody needs more, they can create a PR :)