Function lengthToNumber

src/utils.ts:65–114

(
  length: string | number,
  baseFontSize: number,
  baseLength: number,
  inheritedStyle: Record<string, string | number>,
  percentage = false
)

}

export function lengthToNumber(
  length: string | number,
  baseFontSize: number,
  baseLength: number,
  inheritedStyle: Record<string, string | number>,
  percentage = false
): number | undefined {
  if (typeof length === 'number') return length

  // Convert em and rem values to number (px), convert rad to deg.
  try {
    length = length.trim()

    // Not length: `1px/2px`, `1px 2px`, `1px, 2px`, `calc(1px)`.
    if (/[ /\(,]/.test(length)) return

    // Just a number as string: '100'
    if (length === String(+length)) return +length

    const parsed = new CssDimension(length)
    if (parsed.type === 'length') {
      switch (parsed.unit) {
        case 'em':
          return parsed.value * baseFontSize
        case 'rem':
          return parsed.value * 16
        case 'vw':
          return ~~(
            (parsed.value * (inheritedStyle._viewportWidth as number)) /
            100
          )
        case 'vh':
          return ~~(
            (parsed.value * (inheritedStyle._viewportHeight as number)) /
            100
          )
        default:
          return parsed.value
      }
    } else if (parsed.type === 'angle') {
      return calcDegree(length)
    } else if (parsed.type === 'percentage') {
      if (percentage) {
        return (parsed.value / 100) * baseLength
      }
    }
  } catch {
    // Not a length unit, silently ignore.
  }
}

export function calcDegree(deg: string) {
  const parsed = new CssDimension(deg)