event.js

function getEvent (e) {
  return e || window.event
}

export function rightClick (e) {
  e = getEvent(e)

  if (e.which) {
    return e.which === 3
  }
  if (e.button) {
    return e.button === 2
  }

  return false
}

export function getEventKey (e) {
  e = getEvent(e)
  return e.which || e.keyCode
}

export function position (e) {
  let posx, posy
  e = getEvent(e)

  if (e.touches && e.touches[0]) {
    e = e.touches[0]
  }
  else if (e.changedTouches && e.changedTouches[0]) {
    e = e.changedTouches[0]
  }

  if (e.clientX || e.clientY) {
    posx = e.clientX
    posy = e.clientY
  }
  else if (e.pageX || e.pageY) {
    posx = e.pageX - document.body.scrollLeft - document.documentElement.scrollLeft
    posy = e.pageY - document.body.scrollTop - document.documentElement.scrollTop
  }

  return {
    top: posy,
    left: posx
  }
}

export function targetElement (e) {
  let target
  e = getEvent(e)

  if (e.target) {
    target = e.target
  }
  else if (e.srcElement) {
    target = e.srcElement
  }

  // defeat Safari bug
  if (target.nodeType === 3) {
    target = target.parentNode
  }

  return target
}

// Reasonable defaults
const
  PIXEL_STEP = 10,
  LINE_HEIGHT = 40,
  PAGE_HEIGHT = 800

export function getMouseWheelDistance (e) {
  var
    sX = 0, sY = 0, // spinX, spinY
    pX = 0, pY = 0 // pixelX, pixelY

  // Legacy
  if ('detail' in e) { sY = e.detail }
  if ('wheelDelta' in e) { sY = -e.wheelDelta / 120 }
  if ('wheelDeltaY' in e) { sY = -e.wheelDeltaY / 120 }
  if ('wheelDeltaX' in e) { sX = -e.wheelDeltaX / 120 }

  // side scrolling on FF with DOMMouseScroll
  if ('axis' in e && e.axis === e.HORIZONTAL_AXIS) {
    sX = sY
    sY = 0
  }

  pX = sX * PIXEL_STEP
  pY = sY * PIXEL_STEP

  if ('deltaY' in e) { pY = e.deltaY }
  if ('deltaX' in e) { pX = e.deltaX }

  if ((pX || pY) && e.deltaMode) {
    if (e.deltaMode === 1) { // delta in LINE units
      pX *= LINE_HEIGHT
      pY *= LINE_HEIGHT
    }
    else { // delta in PAGE units
      pX *= PAGE_HEIGHT
      pY *= PAGE_HEIGHT
    }
  }

  // Fall-back if spin cannot be determined
  if (pX && !sX) { sX = (pX < 1) ? -1 : 1 }
  if (pY && !sY) { sY = (pY < 1) ? -1 : 1 }

  /*
   * spinX  -- normalized spin speed (use for zoom) - x plane
   * spinY  -- " - y plane
   * pixelX -- normalized distance (to pixels) - x plane
   * pixelY -- " - y plane
   */
  return {
    spinX: sX,
    spinY: sY,
    pixelX: pX,
    pixelY: pY
  }
}