const getPositionCanvas = e => {
  const { x, y } = canvas.getBoundingClientRect()
  return { x: e.clientX - x, y: e.clientY - y }
}

const normalizeViewPosition = () => {
  const { width, height } = canvasContainer.getBoundingClientRect()

  const [xMin, xMax] = [0, width  - viewWidth ].sort((l, r) => l - r)
  const [yMin, yMax] = [0, height - viewHeight].sort((l, r) => l - r)
  viewX = Math.max(xMin, Math.min(xMax, viewX))
  viewY = Math.max(yMin, Math.min(yMax, viewY))
}