How to detect "swipe" gesture in Litecanvas

code.js

litecanvas();

const taps = new Map()
const actor = {}

function init() {
  actor.x = W/2
  actor.y = H/2

  // on "swipe" move our actor
  listen('swipe', (angle, len) => {
    actor.x += len/2 * cos(angle)
    actor.y += len/2 * sin(angle)
  })
}

function draw() {
  cls(0)
  circfill(actor.x, actor.y, 64, 4)
}

function tap(x, y, id) {
  // store the initial touch/click
  taps.set(id, {x, y})
}

function untap(x, y, id) {
  const from = taps.get(id)
  taps.delete(id)
  
  const angle = atan2(y - from.y, x - from.x);
  const length = hypot(x - from.x, y - from.y);
  emit('swipe', angle, length)
}

Live Demo