How to auto-size text and images

[sijo]

Here’s an implementation of the bisection algorithm I was referring to:

#let fill-height-with-text(min: 0.3em, max: 5em, eps: 0.1em, it) = layout(size => {
  let fits(text-size, it) = {
    measure(width: size.width, { set text(text-size); it }).height <= size.height
  }

  if not fits(min, it) { panic("Content doesn't fit even at minimum text size") }
  if fits(max, it) { set text(max); it }

  let (a, b) = (min, max)
  while b - a > eps {
    let new = 0.5 * (a + b)
    if fits(new, it) {
      a = new
    } else {
      b = new
    }
  }

  set text(a)
  it
})

#block(height: 5cm, fill: luma(80%), fill-height-with-text(lorem(10)))

#block(height: 5cm, fill: luma(80%), columns(2)[
  #fill-height-with-text(lorem(10))

  #fill-height-with-text(lorem(7))
])