text: 'use strict';
  /**
   * 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 createTextSelectionInterceptor = require('./lib/createTextSelectionInterceptor.js');
  var domTextSelectionInterceptor = createTextSelectionInterceptor();
  var fakeTextSelectorInterceptor = createTextSelectionInterceptor(true);
  var Transform = require('./lib/transform.js');
  var makeSvgController = require('./lib/svgController.js');
  var makeDomController = require('./lib/domController.js');
  
  var defaultZoomSpeed = 1;
  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 (makeSvgController.canAttach(domElement)) {
        panController = makeSvgController(domElement, options);
      } else if (makeDomController.canAttach(domElement)) {
        panController = makeDomController(domElement, options);
      }
    }
  
    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;
    // TODO: likely need to unite pinchSpeed with zoomSpeed
    var pinchSpeed = typeof options.pinchSpeed === 'number' ? options.pinchSpeed : 1;
    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 beforeMouseDown = options.beforeMouseDown || noop;
    var speed = typeof options.zoomSpeed === 'number' ? options.zoomSpeed : defaultZoomSpeed;
    var transformOrigin = parseTransformOrigin(options.transformOrigin);
    var textSelection = options.enableTextSelection ? fakeTextSelectorInterceptor : domTextSelectionInterceptor;
  
    validateBounds(bounds);
  
    if (options.autocenter) {
      autocenter();
    }
  
    var frameAnimation;
    var lastTouchEndTime = 0;
    var lastSingleFingerOffset;
    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 paused = false;
  
    listenForEvents();
  
    var api = {
      dispose: dispose,
      moveBy: internalMoveBy,
      moveTo: moveTo,
      smoothMoveTo: smoothMoveTo, 
      centerOn: centerOn,
      zoomTo: publicZoomTo,
      zoomAbs: zoomAbs,
      smoothZoom: smoothZoom,
      smoothZoomAbs: smoothZoomAbs,
      showRectangle: showRectangle,
      zoomToFit: zoomToFit,
  
      pause: pause,
      resume: resume,
      isPaused: isPaused,
  
      getTransform: getTransformModel,
  
      getMinZoom: getMinZoom,
      setMinZoom: setMinZoom,
  
      getMaxZoom: getMaxZoom,
      setMaxZoom: setMaxZoom,
  
      getTransformOrigin: getTransformOrigin,
      setTransformOrigin: setTransformOrigin,
  
      getZoomSpeed: getZoomSpeed,
      setZoomSpeed: setZoomSpeed
    };
  
    eventify(api);
    
    var initialX = typeof options.initialX === 'number' ? options.initialX : transform.x;
    var initialY = typeof options.initialY === 'number' ? options.initialY : transform.y;
    var initialZoom = typeof options.initialZoom === 'number' ? options.initialZoom : transform.scale;
  
    if(initialX != transform.x || initialY != transform.y || initialZoom != transform.scale){
      zoomAbs(initialX, initialY, initialZoom);
    }
  
    return api;
  
    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 getMinZoom() {
      return minZoom;
    }
  
    function setMinZoom(newMinZoom) {
      minZoom = newMinZoom;
    }
  
    function getMaxZoom() {
      return maxZoom;
    }
  
    function setMaxZoom(newMaxZoom) {
      maxZoom = newMaxZoom;
    }
  
    function getTransformOrigin() {
      return transformOrigin;
    }
  
    function setTransformOrigin(newTransformOrigin) {
      transformOrigin = parseTransformOrigin(newTransformOrigin);
    }
  
    function getZoomSpeed() {
      return speed;
    }
  
    function setZoomSpeed(newSpeed) {
      if (!Number.isFinite(newSpeed)) {
        throw new Error('Zoom speed should be a number');
      }
      speed = newSpeed;
    }
  
    function getPoint() {
      return {
        x: transform.x,
        y: transform.y
      };
    }
  
    function moveTo(x, y) {
      transform.x = x;
      transform.y = y;
  
      keepTransformInsideBounds();
  
      triggerEvent('pan');
      makeDirty();
    }
  
    function moveBy(dx, dy) {
      moveTo(transform.x + dx, transform.y + dy);
    }
  
    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);
  
      // TODO: https://github.com/anvaka/panzoom/issues/112
      if (bounds && boundsPadding === 1 && minZoom === 1) {
        transform.scale *= ratio;
        keepTransformInsideBounds();
      } else {
        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 smoothMoveTo(x, y){
      internalMoveBy(x - transform.x, y - transform.y, true);
    }
  
    function zoomToFit(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
  
      var wx = window.innerWidth / 2;
      var wy = window.innerHeight / 2;
  
      var fitRatio = Math.min(wx / (clientRect.width / 2), wy / (clientRect.height / 2));
  
      internalMoveBy(dx, dy, true, () => {smoothZoom(wx , wy, fitRatio)});
      
    }
  
    function internalMoveBy(dx, dy, smooth, done) {
      if (!smooth) {
        moveBy(dx, dy);
        done();
      } else {
        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
          },
          done: done
        })
      }
    }
  
    function scroll(x, y) {
      cancelZoomAnimation();
      moveTo(x, y);
    }
  
    function dispose() {
      releaseEvents();
    }
  
    function listenForEvents() {
      owner.addEventListener('mousedown', onMouseDown, { passive: false });
      owner.addEventListener('dblclick', onDoubleClick, { passive: false });
      owner.addEventListener('touchstart', onTouch, { passive: false });
      owner.addEventListener('keydown', onKeyDown, { passive: false });
  
      // Need to listen on the owner container, so that we are not limited
      // by the size of the scrollable domElement
      wheel.addWheelListener(owner, onMouseWheel, { passive: false });
  
      makeDirty();
    }
  
    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();
      textSelection.release();
  
      triggerPanEnd();
    }
  
    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 * 100);
        var offset = transformOrigin ? getTransformOriginOffset() : midPoint();
        publicZoomTo(offset.x, offset.y, scaleMultiplier);
      }
    }
  
    function midPoint() {
      var ownerRect = owner.getBoundingClientRect();
      return {
        x: ownerRect.width / 2,
        y: ownerRect.height / 2
      };
    }
  
    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) {
      // TODO: Need to unify this filtering names. E.g. use `beforeTouch`
      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) {
      // TODO: Need to unify this filtering names. E.g. use `beforeDoubleClick``
      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);
      lastSingleFingerOffset = offset;
      var point = transformToScreen(offset.x, offset.y);
      mouseX = point.x;
      mouseY = point.y;
  
      smoothScroll.cancel();
      startTouchListenerIfNeeded();
    }
  
    function startTouchListenerIfNeeded() {
      if (touchInProgress) {
        // no need to do anything, as we already listen to events;
        return;
      }
  
      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 point = transformToScreen(offset.x, offset.y);
  
        var dx = point.x - mouseX;
        var dy = point.y - mouseY;
  
        if (dx !== 0 && dy !== 0) {
          triggerPanStart();
        }
        mouseX = point.x;
        mouseY = point.y;
        internalMoveBy(dx, dy);
      } 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);
  
        // since the zoom speed is always based on distance from 1, we need to apply
        // pinch speed only on that distance from 1:
        var scaleMultiplier =
          1 + (currentPinchLength / pinchZoomLength - 1) * pinchSpeed;
  
        var firstTouchPoint = getOffsetXY(t1);
        var secondTouchPoint = getOffsetXY(t2);
        mouseX = (firstTouchPoint.x + secondTouchPoint.x) / 2;
        mouseY = (firstTouchPoint.y + secondTouchPoint.y) / 2;
        if (transformOrigin) {
          var offset = getTransformOriginOffset();
          mouseX = offset.x;
          mouseY = offset.y;
        }
  
        publicZoomTo(mouseX, mouseY, scaleMultiplier);
  
        pinchZoomLength = currentPinchLength;
        e.stopPropagation();
        e.preventDefault();
      }
    }
  
    function handleTouchEnd(e) {
      if (e.touches.length > 0) {
        var offset = getOffsetXY(e.touches[0]);
        var point = transformToScreen(offset.x, offset.y);
        mouseX = point.x;
        mouseY = point.y;
      } else {
        var now = new Date();
        if (now - lastTouchEndTime < doubleTapSpeedInMS) {
          if (transformOrigin) {
            var offset = getTransformOriginOffset();
            smoothZoom(offset.x, offset.y, zoomDoubleClickSpeed);
          } else {
            // We want untransformed x/y here.
            smoothZoom(lastSingleFingerOffset.x, lastSingleFingerOffset.y, zoomDoubleClickSpeed);
          }
        }
  
        lastTouchEndTime = now;
  
        triggerPanEnd();
        releaseTouches();
      }
    }
  
    function getPinchZoomLength(finger1, finger2) {
      var dx = finger1.clientX - finger2.clientX;
      var dy = finger1.clientY - finger2.clientY;
      return Math.sqrt(dx * dx + dy * dy);
    }
  
    function onDoubleClick(e) {
      beforeDoubleClick(e);
      var offset = getOffsetXY(e);
      if (transformOrigin) {
        // TODO: looks like this is duplicated in the file.
        // Need to refactor
        offset = getTransformOriginOffset();
      }
      smoothZoom(offset.x, offset.y, zoomDoubleClickSpeed);
    }
  
    function onMouseDown(e) {
      // if client does not want to handle this event - just ignore the call
      if (beforeMouseDown(e)) return;
  
      if (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);
      textSelection.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;
  
      internalMoveBy(dx, dy);
    }
  
    function onMouseUp() {
      textSelection.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;
      touchInProgress = false;
    }
  
    function onMouseWheel(e) {
      // if client does not want to handle this event - just ignore the call
      if (beforeWheel(e)) return;
  
      smoothScroll.cancel();
  
      var delta = e.deltaY;
      if (e.deltaMode > 0) delta *= 100;
  
      var scaleMultiplier = getScaleMultiplier(delta);
  
      if (scaleMultiplier !== 1) {
        var offset = transformOrigin
          ? getTransformOriginOffset()
          : 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);
        },
        done: triggerZoomEnd
      });
    }
  
    function smoothZoomAbs(clientX, clientY, toScaleValue) {
      var fromValue = transform.scale;
      var from = { scale: fromValue };
      var to = { scale: toScaleValue };
  
      smoothScroll.cancel();
      cancelZoomAnimation();
  
      zoomToAnimation = animate(from, to, {
        step: function (v) {
          zoomAbs(clientX, clientY, v.scale);
        }
      });
    }
  
    function getTransformOriginOffset() {
      var ownerRect = owner.getBoundingClientRect();
      return {
        x: ownerRect.width * transformOrigin.x,
        y: ownerRect.height * transformOrigin.y
      };
    }
  
    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 sign = Math.sign(delta);
      var deltaAdjustedSpeed = Math.min(0.25, Math.abs(speed * delta / 128));
      return 1 - sign * deltaAdjustedSpeed;
    }
  
    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 triggerZoomEnd() {
      triggerEvent('zoomend');
    }
  
    function triggerEvent(name) {
      api.fire(name, api);
    }
  }
  
  function parseTransformOrigin(options) {
    if (!options) return;
    if (typeof options === 'object') {
      if (!isNumber(options.x) || !isNumber(options.y))
        failTransformOrigin(options);
      return options;
    }
  
    failTransformOrigin();
  }
  
  function failTransformOrigin(options) {
    console.error(options);
    throw new Error(
      [
        'Cannot parse transform origin.',
        'Some good examples:',
        '  "center center" can be achieved with {x: 0.5, y: 0.5}',
        '  "top center" can be achieved with {x: 0.5, y: 0}',
        '  "bottom right" can be achieved with {x: 1, y: 1}'
      ].join('\n')
    );
  }
  
  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;
  
    for (var i = 0; i < scripts.length; ++i) {
      var x = scripts[i];
      if (x.src && x.src.match(/\bpanzoom(\.min)?\.js/)) {
        panzoomScript = x;
        break;
      }
    }
  
    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 j = 0; j < attrs.length; ++j) {
        var attr = attrs[j];
        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();
  	