index.js

'use strict';

/* globals SVGElement */
/**
 * Allows to drag and zoom svg elements
 */
var wheel = require('wheel')
var animate = require('amator')
var eventify = require('ngraph.events');
var kinetic = require('./lib/kinetic.js')
var preventTextSelection = require('./lib/textSelectionInterceptor.js')()
var Transform = require('./lib/transform.js');
var makeSvgController = require('./lib/svgController.js')
var makeDomController = require('./lib/domController.js')

var defaultZoomSpeed = 0.065
var defaultDoubleTapZoomSpeed = 1.75
var doubleTapSpeedInMS = 300

module.exports = createPanZoom

/**
 * Creates a new instance of panzoom, so that an object can be panned and zoomed
 *
 * @param {DOMElement} domElement where panzoom should be attached.
 * @param {Object} options that configure behavior.
 */
function createPanZoom(domElement, options) {
  options = options || {}

  var panController = options.controller

  if (!panController) {
    if (domElement instanceof SVGElement) {
      panController = makeSvgController(domElement)
    }

    if (domElement instanceof HTMLElement) {
      panController = makeDomController(domElement)
    }
  }

  if (!panController) {
    throw new Error('Cannot create panzoom for the current type of dom element')
  }
  var owner = panController.getOwner()
  // just to avoid GC pressure, every time we do intermediate transform
  // we return this object. For internal use only. Never give it back to the consumer of this library
  var storedCTMResult = {x: 0, y: 0}

  var isDirty = false
  var transform = new Transform()

  if (panController.initTransform) {
    panController.initTransform(transform)
  }

  var filterKey = typeof options.filterKey === 'function' ? options.filterKey : noop;
  var realPinch = typeof options.realPinch === 'boolean' ? options.realPinch : false
  var bounds = options.bounds
  var maxZoom = typeof options.maxZoom === 'number' ? options.maxZoom : Number.POSITIVE_INFINITY
  var minZoom = typeof options.minZoom === 'number' ? options.minZoom : 0

  var boundsPadding = typeof options.boundsPadding === 'number' ? options.boundsPadding : 0.05
  var zoomDoubleClickSpeed = typeof options.zoomDoubleClickSpeed === 'number' ? options.zoomDoubleClickSpeed : defaultDoubleTapZoomSpeed
  var beforeWheel = options.beforeWheel || noop
  var beforePan = options.beforePan || noop
  var moveXCondition = options.moveXCondition || noop
  var moveYCondition = options.moveYCondition || noop
  var speed = typeof options.zoomSpeed === 'number' ? options.zoomSpeed : defaultZoomSpeed

  validateBounds(bounds)

  if (options.autocenter) {
    autocenter()
  }

  var frameAnimation

  var lastTouchEndTime = 0

  var touchInProgress = false

  // We only need to fire panstart when actual move happens
  var panstartFired = false

  // cache mouse coordinates here
  var mouseX
  var mouseY

  var pinchZoomLength

  var smoothScroll
  if ('smoothScroll' in options && !options.smoothScroll) {
    // If user explicitly asked us not to use smooth scrolling, we obey
    smoothScroll = rigidScroll()
  } else {
    // otherwise we use forward smoothScroll settings to kinetic API
    // which makes scroll smoothing.
    smoothScroll = kinetic(getPoint, scroll, options.smoothScroll)
  }

  var moveByAnimation
  var zoomToAnimation

  var multitouch
  var panPaused = false
  var zoomPaused = false
  var paused = false

  listenForEvents()

  var api = {
    dispose: dispose,
    moveBy: internalMoveBy,
    moveTo: moveTo,
    centerOn: centerOn,
    zoomTo: publicZoomTo,
    zoomAbs: zoomAbs,
    smoothZoom: smoothZoom,
    getTransform: getTransformModel,
    showRectangle: showRectangle,

    updateMinZoom: updateMinZoom,
    updateMaxZoom: updateMaxZoom,
    updateBounds: updateBounds,

    pausePan: pausePan,
    resumePan: resumePan,
    isPanPaused: isPanPaused,

    pauseZoom: pauseZoom,
    resumeZoom: resumeZoom,
    isZoomPaused: isZoomPaused,

    pauseKeys: pauseKeys,
    resumeKeys: resumeKeys,
    pause: pause,
    resume: resume,
    isPaused: isPaused,
  }

  eventify(api);

  return api;

  function updateBounds(newBounds)
  {
    validateBounds(newBounds)
    bounds = newBounds
  }

  function updateMinZoom(newMin)
  {
    minZoom = newMin
  }

  function updateMaxZoom(newMax)
  {
    maxZoom = newMax
  }

  function pausePan() {
    releasePanEvents()
    pausedPan = true
  }

  function resumePan() {
    if (panPaused) {
      listenForPanEvents()
      pausedPan = false
    }
  }

  function isPanPaused() {
    return pausedPan;
  }

  function pauseZoom() {
    releaseZoomEvents()
    zoomPaused = true
  }

  function resumeZoom() {
    if (panPaused) {
      listenForZoomEvents()
      zoomPaused = false
    }
  }

  function isZoomPaused() {
    return zoomPaused;
  }

  function pauseKeys () {
    releaseKeyEvents()
  }

  function resumeKeys () {
    listenForKeyEvents()
  }

  function pause() {
    releaseEvents()
    paused = true
  }

  function resume() {
    if (paused) {
      listenForEvents()
      paused = false
    }
  }

  function isPaused() {
    return paused;
  }

  function showRectangle(rect) {
    // TODO: this duplicates autocenter. I think autocenter should go.
    var clientRect = owner.getBoundingClientRect()
    var size = transformToScreen(clientRect.width, clientRect.height)

    var rectWidth = rect.right - rect.left
    var rectHeight = rect.bottom - rect.top
    if (!Number.isFinite(rectWidth) || !Number.isFinite(rectHeight)) {
      throw new Error('Invalid rectangle');
    }

    var dw = size.x/rectWidth
    var dh = size.y/rectHeight
    var scale = Math.min(dw, dh)
    transform.x = -(rect.left + rectWidth/2) * scale + size.x/2
    transform.y = -(rect.top + rectHeight/2) * scale + size.y/2
    transform.scale = scale
  }

  function transformToScreen(x, y) {
    if (panController.getScreenCTM) {
      var parentCTM = panController.getScreenCTM()
      var parentScaleX = parentCTM.a
      var parentScaleY = parentCTM.d
      var parentOffsetX = parentCTM.e
      var parentOffsetY = parentCTM.f
      storedCTMResult.x = x * parentScaleX - parentOffsetX
      storedCTMResult.y = y * parentScaleY - parentOffsetY
    } else {
      storedCTMResult.x = x
      storedCTMResult.y = y
    }

    return storedCTMResult
  }

  function autocenter() {
    var w // width of the parent
    var h // height of the parent
    var left = 0
    var top = 0
    var sceneBoundingBox = getBoundingBox()
    if (sceneBoundingBox) {
      // If we have bounding box - use it.
      left = sceneBoundingBox.left
      top = sceneBoundingBox.top
      w = sceneBoundingBox.right - sceneBoundingBox.left
      h = sceneBoundingBox.bottom - sceneBoundingBox.top
    } else {
      // otherwise just use whatever space we have
      var ownerRect = owner.getBoundingClientRect();
      w = ownerRect.width
      h = ownerRect.height
    }
    var bbox = panController.getBBox()
    if (bbox.width === 0 || bbox.height === 0) {
      // we probably do not have any elements in the SVG
      // just bail out;
      return;
    }
    var dh = h/bbox.height
    var dw = w/bbox.width
    var scale = Math.min(dw, dh)
    transform.x = -(bbox.left + bbox.width/2) * scale + w/2 + left
    transform.y = -(bbox.top + bbox.height/2) * scale + h/2 + top
    transform.scale = scale
  }

  function getTransformModel() {
    // TODO: should this be read only?
    return transform
  }

  function getPoint() {
    return {
      x: transform.x,
      y: transform.y
    }
  }

  function moveTo(x, y) {
    if (panPaused) return

     transform.x = x
     transform.y = y

     keepTransformInsideBounds()

     triggerEvent('pan')
     makeDirty()
   }

  function moveBy(dx, dy) {
    var newx = transform.x + dx
    var newy = transform.y + dy
    var movex = moveXCondition(transform.x, newx)
    var movey = moveYCondition(transform.y, newy)
    if (!movex && !movey) return

    if (movex && movey)
       moveTo(newx, newy)

    if (movex)
       moveTo(newx, transform.y)

    if (movey)
       moveTo(transform.x, newy)
  }

  function keepTransformInsideBounds() {
    var boundingBox = getBoundingBox()
    if (!boundingBox) return

    var adjusted = false
    var clientRect = getClientRect()

    var diff = boundingBox.left - clientRect.right
    if (diff > 0) {
      transform.x += diff
      adjusted = true
    }
    // check the other side:
    diff = boundingBox.right - clientRect.left
    if (diff < 0) {
      transform.x += diff
      adjusted = true
    }

    // y axis:
    diff = boundingBox.top - clientRect.bottom
    if (diff > 0) {
      // we adjust transform, so that it matches exactly our bounding box:
      // transform.y = boundingBox.top - (boundingBox.height + boundingBox.y) * transform.scale =>
      // transform.y = boundingBox.top - (clientRect.bottom - transform.y) =>
      // transform.y = diff + transform.y =>
      transform.y += diff
      adjusted = true
    }

    diff = boundingBox.bottom - clientRect.top
    if (diff < 0) {
      transform.y += diff
      adjusted = true
    }
    return adjusted
  }

  /**
   * Returns bounding box that should be used to restrict scene movement.
   */
  function getBoundingBox() {
    if (!bounds) return // client does not want to restrict movement

    if (typeof bounds === 'boolean') {
      // for boolean type we use parent container bounds
      var ownerRect = owner.getBoundingClientRect()
      var sceneWidth = ownerRect.width
      var sceneHeight = ownerRect.height

      return {
        left: sceneWidth * boundsPadding,
        top: sceneHeight * boundsPadding,
        right: sceneWidth * (1 - boundsPadding),
        bottom: sceneHeight * (1 - boundsPadding),
      }
    }

    return bounds
  }

  function getClientRect() {
    var bbox = panController.getBBox()
    var leftTop = client(bbox.left, bbox.top)

    return {
      left: leftTop.x,
      top: leftTop.y,
      right: bbox.width * transform.scale + leftTop.x,
      bottom: bbox.height * transform.scale + leftTop.y
    }
  }

  function client(x, y) {
    return {
      x: (x * transform.scale) + transform.x,
      y: (y * transform.scale) + transform.y
    }
  }

  function makeDirty() {
    isDirty = true
    frameAnimation = window.requestAnimationFrame(frame)
  }

  function zoomByRatio(clientX, clientY, ratio) {
    if (isNaN(clientX) || isNaN(clientY) || isNaN(ratio)) {
      throw new Error('zoom requires valid numbers')
    }

    var newScale = transform.scale * ratio

    if (newScale < minZoom) {
      if (transform.scale === minZoom) return;

      ratio = minZoom / transform.scale
    }
    if (newScale > maxZoom) {
      if (transform.scale === maxZoom) return;

      ratio = maxZoom / transform.scale
    }

    var size = transformToScreen(clientX, clientY)

    transform.x = size.x - ratio * (size.x - transform.x)
    transform.y = size.y - ratio * (size.y - transform.y)

    var transformAdjusted = keepTransformInsideBounds()
    if (!transformAdjusted) transform.scale *= ratio

    triggerEvent('zoom')

    makeDirty()
  }

  function zoomAbs(clientX, clientY, zoomLevel) {
    var ratio = zoomLevel / transform.scale
    zoomByRatio(clientX, clientY, ratio)
  }

  function centerOn(ui) {
    var parent = ui.ownerSVGElement
    if (!parent) throw new Error('ui element is required to be within the scene')

    // TODO: should i use controller's screen CTM?
    var clientRect = ui.getBoundingClientRect()
    var cx = clientRect.left + clientRect.width/2
    var cy = clientRect.top + clientRect.height/2

    var container = parent.getBoundingClientRect()
    var dx = container.width/2 - cx
    var dy = container.height/2 - cy

    internalMoveBy(dx, dy, true)
  }

  function internalMoveBy(dx, dy, smooth) {
    if (!smooth) {
      return moveBy(dx, dy)
    }

    if (moveByAnimation) moveByAnimation.cancel()

    var from = { x: 0, y: 0 }
    var to = { x: dx, y : dy }
    var lastX = 0
    var lastY = 0

    moveByAnimation = animate(from, to, {
      step: function(v) {
        moveBy(v.x - lastX, v.y - lastY)

        lastX = v.x
        lastY = v.y
      }
    })
  }

  function scroll(x, y) {
    cancelZoomAnimation()
    moveTo(x, y)
  }

  function dispose() {
    releaseEvents();
  }

  function listenForEvents() {
    owner.addEventListener('mousedown', onMouseDown)
    owner.addEventListener('dblclick', onDoubleClick)
    owner.addEventListener('touchstart', onTouch)
    owner.addEventListener('keydown', onKeyDown)

    // Need to listen on the owner container, so that we are not limited
    // by the size of the scrollable domElement
    wheel.addWheelListener(owner, onMouseWheel)

    makeDirty()
  }

   function listenForPanEvents() {
     owner.addEventListener('mousedown', onMouseDown)
     owner.addEventListener('touchstart', onTouch)

     makeDirty()
   }

  function listenForZoomEvents() {
    owner.addEventListener('dblclick', onDoubleClick)
    wheel.addWheelListener(owner, onMouseWheel)

    makeDirty()
  }

  function listenForKeyEvents() {
    owner.addEventListener('keydown', onKeyDown)
  }

  function releaseKeyEvents() {
    owner.removeEventListener('keydown', onKeyDown)
  }

  function releaseEvents() {
    wheel.removeWheelListener(owner, onMouseWheel)
    owner.removeEventListener('mousedown', onMouseDown)
    owner.removeEventListener('keydown', onKeyDown)
    owner.removeEventListener('dblclick', onDoubleClick)
    owner.removeEventListener('touchstart', onTouch)

    if (frameAnimation) {
      window.cancelAnimationFrame(frameAnimation)
      frameAnimation = 0
    }

    smoothScroll.cancel()

    releaseDocumentMouse()
    releaseTouches()

    triggerPanEnd()
  }

  function releasePanEvents() {
    owner.removeEventListener('mousedown', onMouseDown)
    owner.removeEventListener('touchstart', onTouch)

    releaseDocumentMouse()
    releaseTouches()
    triggerPanEnd()
  }

  function releaseZoomEvents() {
    wheel.removeWheelListener(owner, onMouseWheel)
    owner.removeEventListener('dblclick', onDoubleClick)
    smoothScroll.cancel()
  }

  function frame() {
    if (isDirty) applyTransform()
  }

  function applyTransform() {
    isDirty = false

    // TODO: Should I allow to cancel this?
    panController.applyTransform(transform)

    triggerEvent('transform')
    frameAnimation = 0
  }

  function onKeyDown(e) {
    var x = 0, y = 0, z = 0
    if (e.keyCode === 38) {
      y = 1 // up
    } else if (e.keyCode === 40) {
      y = -1 // down
    } else if (e.keyCode === 37) {
      x = 1 // left
    } else if (e.keyCode === 39) {
      x = -1 // right
    } else if (e.keyCode === 189 || e.keyCode === 109) { // DASH or SUBTRACT
      z = 1 // `-` -  zoom out
    } else if (e.keyCode === 187 || e.keyCode === 107) { // EQUAL SIGN or ADD
      z = -1 // `=` - zoom in (equal sign on US layout is under `+`)
    }

    if (filterKey(e, x, y, z)) {
      // They don't want us to handle the key: https://github.com/anvaka/panzoom/issues/45
      return;
    }

    if (x || y) {
      e.preventDefault()
      e.stopPropagation()

      var clientRect = owner.getBoundingClientRect()
      // movement speed should be the same in both X and Y direction:
      var offset = Math.min(clientRect.width, clientRect.height)
      var moveSpeedRatio = 0.05
      var dx = offset * moveSpeedRatio * x
      var dy = offset * moveSpeedRatio * y
      // TODO: currently we do not animate this. It could be better to have animation
      internalMoveBy(dx, dy)
    }

    if (z) {
      var scaleMultiplier = getScaleMultiplier(z)
      var ownerRect = owner.getBoundingClientRect()
      publicZoomTo(ownerRect.width/2, ownerRect.height/2, scaleMultiplier)
    }
  }

  function onTouch(e) {
    // let the override the touch behavior
    beforeTouch(e);

    if (e.touches.length === 1) {
      return handleSingleFingerTouch(e, e.touches[0])
    } else if (e.touches.length === 2) {
      // handleTouchMove() will care about pinch zoom.
      pinchZoomLength = getPinchZoomLength(e.touches[0], e.touches[1])
      multitouch  = true
      startTouchListenerIfNeeded()
    }
  }

  function beforeTouch(e) {
    if (options.onTouch && !options.onTouch(e)) {
      // if they return `false` from onTouch, we don't want to stop
      // events propagation. Fixes https://github.com/anvaka/panzoom/issues/12
      return
    }

    e.stopPropagation()
    e.preventDefault()
  }

  function beforeDoubleClick(e) {
    if (options.onDoubleClick && !options.onDoubleClick(e)) {
      // if they return `false` from onTouch, we don't want to stop
      // events propagation. Fixes https://github.com/anvaka/panzoom/issues/46
      return
    }

    e.preventDefault()
    e.stopPropagation()
  }

  function handleSingleFingerTouch(e) {
    var touch = e.touches[0]
    var offset = getOffsetXY(touch)
    mouseX = offset.x
    mouseY = offset.y

    smoothScroll.cancel()
    startTouchListenerIfNeeded()
  }

  function startTouchListenerIfNeeded() {
    if (!touchInProgress) {
      touchInProgress = true
      document.addEventListener('touchmove', handleTouchMove)
      document.addEventListener('touchend', handleTouchEnd)
      document.addEventListener('touchcancel', handleTouchEnd)
    }
  }

  function handleTouchMove(e) {
    if (e.touches.length === 1) {
      e.stopPropagation()
      var touch = e.touches[0]

      var offset = getOffsetXY(touch)

      var dx = offset.x - mouseX
      var dy = offset.y - mouseY

      if (dx !== 0 && dy !== 0) {
        triggerPanStart()
      }
      mouseX = offset.x
      mouseY = offset.y
      var point = transformToScreen(dx, dy)
      internalMoveBy(point.x, point.y)
    } else if (e.touches.length === 2) {
      // it's a zoom, let's find direction
      multitouch = true
      var t1 = e.touches[0]
      var t2 = e.touches[1]
      var currentPinchLength = getPinchZoomLength(t1, t2)

      var scaleMultiplier = 1

      if (realPinch) {
        scaleMultiplier = currentPinchLength / pinchZoomLength
      } else {
        var delta = 0
        if (currentPinchLength < pinchZoomLength) {
          delta = 1
        } else if (currentPinchLength > pinchZoomLength) {
          delta = -1
        }

        scaleMultiplier = getScaleMultiplier(delta)
      }

      mouseX = (t1.clientX + t2.clientX)/2
      mouseY = (t1.clientY + t2.clientY)/2

      publicZoomTo(mouseX, mouseY, scaleMultiplier)

      pinchZoomLength = currentPinchLength
      e.stopPropagation()
      e.preventDefault()
    }
  }

  function handleTouchEnd(e) {
    if (e.touches.length > 0) {
      var offset = getOffsetXY(e.touches[0])
      mouseX = offset.x
      mouseY = offset.y
    } else {
      var now = new Date()
      if (now - lastTouchEndTime < doubleTapSpeedInMS) {
        smoothZoom(mouseX, mouseY, zoomDoubleClickSpeed)
      }

      lastTouchEndTime = now

      touchInProgress = false
      triggerPanEnd()
      releaseTouches()
    }
  }

  function getPinchZoomLength(finger1, finger2) {
    return Math.sqrt((finger1.clientX - finger2.clientX) * (finger1.clientX - finger2.clientX) +
      (finger1.clientY - finger2.clientY) * (finger1.clientY - finger2.clientY))
  }

  function onDoubleClick(e) {
    beforeDoubleClick(e);
    var offset = getOffsetXY(e)
    smoothZoom(offset.x, offset.y, zoomDoubleClickSpeed)
  }

  function onMouseDown(e) {
    //give the option to add other deps for executing
    if (beforePan(e) || touchInProgress) {
      // modern browsers will fire mousedown for touch events too
      // we do not want this: touch is handled separately.
      e.stopPropagation()
      return false
    }
    // for IE, left click == 1
    // for Firefox, left click == 0
    var isLeftButton = ((e.button === 1 && window.event !== null) || e.button === 0)
    if (!isLeftButton) return

    smoothScroll.cancel()

    var offset = getOffsetXY(e);
    var point = transformToScreen(offset.x, offset.y)
    mouseX = point.x
    mouseY = point.y

    // We need to listen on document itself, since mouse can go outside of the
    // window, and we will loose it
    document.addEventListener('mousemove', onMouseMove)
    document.addEventListener('mouseup', onMouseUp)

    preventTextSelection.capture(e.target || e.srcElement)

    return false
  }

  function onMouseMove(e) {
    // no need to worry about mouse events when touch is happening
    if (touchInProgress) return

    triggerPanStart()

    var offset = getOffsetXY(e);
    var point = transformToScreen(offset.x, offset.y)
    var dx = point.x - mouseX
    var dy = point.y - mouseY

    mouseX = point.x
    mouseY = point.y
    beforePan(e) ||
    internalMoveBy(dx, dy)
  }

  function onMouseUp() {

    preventTextSelection.release()
    triggerPanEnd()
    releaseDocumentMouse()
  }

  function releaseDocumentMouse() {
    document.removeEventListener('mousemove', onMouseMove)
    document.removeEventListener('mouseup', onMouseUp)
    panstartFired = false
  }

  function releaseTouches() {
    document.removeEventListener('touchmove', handleTouchMove)
    document.removeEventListener('touchend', handleTouchEnd)
    document.removeEventListener('touchcancel', handleTouchEnd)
    panstartFired = false
    multitouch = false
  }

  function onMouseWheel(e) {
    // if client does not want to handle this event or if zoom is paused- just ignore the call
    if (zoomPaused || beforeWheel(e)) return

    smoothScroll.cancel()

    var scaleMultiplier = getScaleMultiplier(e.deltaY)

    if (scaleMultiplier !== 1) {
      var offset = getOffsetXY(e)
      publicZoomTo(offset.x, offset.y, scaleMultiplier)
      e.preventDefault()
    }
  }

  function getOffsetXY(e) {
    var offsetX, offsetY;
    // I tried using e.offsetX, but that gives wrong results for svg, when user clicks on a path.
    var ownerRect = owner.getBoundingClientRect();
    offsetX = e.clientX - ownerRect.left
    offsetY = e.clientY - ownerRect.top

    return {x: offsetX, y: offsetY};
  }

  function smoothZoom(clientX, clientY, scaleMultiplier) {
      var fromValue = transform.scale
      var from = {scale: fromValue}
      var to = {scale: scaleMultiplier * fromValue}

      smoothScroll.cancel()
      cancelZoomAnimation()

      zoomToAnimation = animate(from, to, {
        step: function(v) {
          zoomAbs(clientX, clientY, v.scale)
        }
      })
  }

  function publicZoomTo(clientX, clientY, scaleMultiplier) {
      smoothScroll.cancel()
      cancelZoomAnimation()
      return zoomByRatio(clientX, clientY, scaleMultiplier)
  }

  function cancelZoomAnimation() {
      if (zoomToAnimation) {
          zoomToAnimation.cancel()
          zoomToAnimation = null
      }
  }

  function getScaleMultiplier(delta) {
    var scaleMultiplier = 1
    if (delta > 0) { // zoom out
      scaleMultiplier = (1 - speed)
    } else if (delta < 0) { // zoom in
      scaleMultiplier = (1 + speed)
    }

    return scaleMultiplier
  }

  function triggerPanStart() {
    if (!panstartFired) {
      triggerEvent('panstart')
      panstartFired = true
      smoothScroll.start()
    }
  }

  function triggerPanEnd() {
    if (panstartFired) {
      // we should never run smooth scrolling if it was multitouch (pinch zoom animation):
      if (!multitouch) smoothScroll.stop()
      triggerEvent('panend')
    }
  }

  function triggerEvent(name) {
    api.fire(name, api);
  }
}

function noop() { }

function validateBounds(bounds) {
  var boundsType = typeof bounds
  if (boundsType === 'undefined' || boundsType === 'boolean') return // this is okay
  // otherwise need to be more thorough:
  var validBounds = isNumber(bounds.left) && isNumber(bounds.top) &&
    isNumber(bounds.bottom) && isNumber(bounds.right)

  if (!validBounds) throw new Error('Bounds object is not valid. It can be: ' +
    'undefined, boolean (true|false) or an object {left, top, right, bottom}')
}

function isNumber(x) {
  return Number.isFinite(x)
}

// IE 11 does not support isNaN:
function isNaN(value) {
  if (Number.isNaN) {
    return Number.isNaN(value)
  }

  return value !== value
}

function rigidScroll() {
  return {
    start: noop,
    stop: noop,
    cancel: noop
  }
}


function autoRun() {
  if (typeof document === 'undefined') return

  var scripts = document.getElementsByTagName('script');
  if (!scripts) return;
  var panzoomScript;

  Array.from(scripts).forEach(function(x) {
    if (x.src && x.src.match(/\bpanzoom(\.min)?\.js/)) {
      panzoomScript = x
    }
  })

  if (!panzoomScript) return;

  var query = panzoomScript.getAttribute('query')
  if (!query) return;

  var globalName = panzoomScript.getAttribute('name') || 'pz'
  var started = Date.now()

  tryAttach();

  function tryAttach() {
    var el = document.querySelector(query)
    if (!el) {
      var now = Date.now()
      var elapsed = now - started;
      if (elapsed < 2000) {
        // Let's wait a bit
        setTimeout(tryAttach, 100);
        return;
      }
      // If we don't attach within 2 seconds to the target element, consider it a failure
      console.error('Cannot find the panzoom element', globalName)
      return
    }
    var options = collectOptions(panzoomScript)
    console.log(options)
    window[globalName] = createPanZoom(el, options);
  }

  function collectOptions(script) {
    var attrs = script.attributes;
    var options = {};
    for(var i = 0; i < attrs.length; ++i) {
      var attr = attrs[i];
      var nameValue = getPanzoomAttributeNameValue(attr);
      if (nameValue) {
        options[nameValue.name] = nameValue.value
      }
    }

    return options;
  }

  function getPanzoomAttributeNameValue(attr) {
    if (!attr.name) return;
    var isPanZoomAttribute = attr.name[0] === 'p' && attr.name[1] === 'z' && attr.name[2] === '-';

    if (!isPanZoomAttribute) return;

    var name = attr.name.substr(3)
    var value = JSON.parse(attr.value);
    return {name: name, value: value};
  }
}

autoRun();