Superalgos/BottomSpace/PlayStopButton.js

function newPlayStopButton () {
  var thisObject = {
    container: undefined,
    setDatetime: setDatetime,
    draw: draw,
    getContainer: getContainer,     // returns the inner most container that holds the point received by parameter.
    initialize: initialize
  }

  var container = newContainer()
  container.initialize()
  thisObject.container = container

  thisObject.container.frame.width = 50
  thisObject.container.frame.height = BOTTOM_SPACE_HEIGHT

  resize()

  container.isDraggeable = false
  container.isClickeable = true

  let play
  let stop
  let canDraw = false
  let showing = 'Play'
  let image

  let datetime
  let timePeriod

  return thisObject

  function initialize () {
    play = new Image()

    play.onload = onImageLoad

    function onImageLoad () {
      image = play
      canDraw = true
    }

    play.src = window.canvasApp.urlPrefix + 'Images/Icons/play.png'

    stop = new Image()

    stop.src = window.canvasApp.urlPrefix + 'Images/Icons/pause.png'

    thisObject.container.eventHandler.listenToEvent('onMouseClick', onClick)

    viewPort.eventHandler.listenToEvent('Zoom Changed', onZoomChanged)
    timePeriod = INITIAL_TIME_PERIOD

    window.canvasApp.eventHandler.listenToEvent('Browser Resized', resize)
  }

  function resize () {
    container.frame.position.x = viewPort.visibleArea.topLeft.x + 150 * 5
    container.frame.position.y = viewPort.visibleArea.bottomLeft.y
  }

  function onClick () {
    let sessionToken = window.localStorage.getItem('sessionToken')

    if (sessionToken === null || sessionToken === '') {
            /* not logged in */
      return
    }

    switch (showing) {

      case 'Play': {
        image = stop
        showing = 'Stop'

        let UI_COMMANDS = {
          beginDatetime: datetime,
          endDatetime: undefined,
          timePeriod: timePeriod,
          startMode: window.CURRENT_START_MODE,
          eventHandler: thisObject.container.eventHandler
        }

        cloudVM.onBotPlayPressed(UI_COMMANDS)

        break
      }
      case 'Stop': {
        image = play
        showing = 'Play'

        cloudVM.onBotStopPressed()

        break
      }
    }
  }

  function onZoomChanged (event) {
    timePeriod = recalculatePeriod(event.newLevel)
  }

  function setDatetime (pDatetime) {
    datetime = new Date(pDatetime)
  }

  function getContainer (point) {
    let container

        /* First we check if this point is inside this object UI. */

    if (thisObject.container.frame.isThisPointHere(point, true) === true) {
      return this.container
    } else {
            /* This point does not belong to this space. */

      return undefined
    }
  }

  function draw () {
    let sessionToken = window.localStorage.getItem('sessionToken')

    if (sessionToken === null || sessionToken === '') {
            /* not logged in */
      return
    }

    thisObject.container.frame.draw(false, false)

    let breakpointsHeight = 14

    if (canDraw === false) { return }

    let imageHeight = 20
    let imageWidth = 20

    let imagePoint = {
      x: thisObject.container.frame.width / 2 - imageWidth / 2,
      y: thisObject.container.frame.height / 2 - imageHeight / 2 + breakpointsHeight
    }

    imagePoint = thisObject.container.frame.frameThisPoint(imagePoint)

    browserCanvasContext.drawImage(image, imagePoint.x, imagePoint.y, imageWidth, imageHeight)
  }
}