svg-pan-zoom-m/src/svg-pan-zoom.js

JavaScript library for panning and zooming an SVG image from the mouse, touches and programmatically.

var Wheel = require("./uniwheel"),
  ControlIcons = require("./control-icons"),
  Utils = require("./utilities"),
  SvgUtils = require("./svg-utilities"),
  ShadowViewport = require("./shadow-viewport");

var SvgPanZoom = function(svg, options) {
  this.init(svg, options);
};

var optionsDefaults = {
  viewportSelector: ".svg-pan-zoom_viewport", // Viewport selector. Can be querySelector string or SVGElement
  panEnabled: true, // enable or disable panning (default enabled)
  controlIconsEnabled: false, // insert icons to give user an option in addition to mouse events to control pan/zoom (default disabled)
  zoomEnabled: true, // enable or disable zooming (default enabled)
  dblClickZoomEnabled: true, // enable or disable zooming by double clicking (default enabled)
  mouseWheelZoomEnabled: true, // enable or disable zooming by mouse wheel (default enabled)
  preventMouseEventsDefault: true, // enable or disable preventDefault for mouse events
  zoomScaleSensitivity: 0.1, // Zoom sensitivity
  minZoom: 0.5, // Minimum Zoom level
  maxZoom: 10, // Maximum Zoom level
  fit: true, // enable or disable viewport fit in SVG (default true)
  contain: false, // enable or disable viewport contain the svg (default false)
  center: true, // enable or disable viewport centering in SVG (default true)
  refreshRate: "auto", // Maximum number of frames per second (altering SVG's viewport)
  beforeZoom: null,
  onZoom: null,
  beforePan: null,
  onPan: null,
  customEventsHandler: null,
  eventsListenerElement: null,
  onUpdatedCTM: null,
  onlyMouseWheel: false // jusitfy if use `wheel` or `mousewheel` event
};

var passiveListenerOption = { passive: true };

SvgPanZoom.prototype.init = function(svg, options) {
  var that = this;

  this.svg = svg;
  this.defs = svg.querySelector("defs");

  // Add default attributes to SVG
  SvgUtils.setupSvgAttributes(this.svg);

  // Set options
  this.options = Utils.extend(Utils.extend({}, optionsDefaults), options);

  // Set default state
  this.state = "none";

  // Get dimensions
  var boundingClientRectNormalized = SvgUtils.getBoundingClientRectNormalized(
    svg
  );
  this.width = boundingClientRectNormalized.width;
  this.height = boundingClientRectNormalized.height;

  // Init shadow viewport
  this.viewport = ShadowViewport(
    SvgUtils.getOrCreateViewport(this.svg, this.options.viewportSelector),
    {
      svg: this.svg,
      width: this.width,
      height: this.height,
      fit: this.options.fit,
      contain: this.options.contain,
      center: this.options.center,
      refreshRate: this.options.refreshRate,
      // Put callbacks into functions as they can change through time
      beforeZoom: function(oldScale, newScale) {
        if (that.viewport && that.options.beforeZoom) {
          return that.options.beforeZoom(oldScale, newScale);
        }
      },
      onZoom: function(scale) {
        if (that.viewport && that.options.onZoom) {
          return that.options.onZoom(scale);
        }
      },
      beforePan: function(oldPoint, newPoint) {
        if (that.viewport && that.options.beforePan) {
          return that.options.beforePan(oldPoint, newPoint);
        }
      },
      onPan: function(point) {
        if (that.viewport && that.options.onPan) {
          return that.options.onPan(point);
        }
      },
      onUpdatedCTM: function(ctm) {
        if (that.viewport && that.options.onUpdatedCTM) {
          return that.options.onUpdatedCTM(ctm);
        }
      }
    }
  );

  // Wrap callbacks into public API context
  var publicInstance = this.getPublicInstance();
  publicInstance.setBeforeZoom(this.options.beforeZoom);
  publicInstance.setOnZoom(this.options.onZoom);
  publicInstance.setBeforePan(this.options.beforePan);
  publicInstance.setOnPan(this.options.onPan);
  publicInstance.setOnUpdatedCTM(this.options.onUpdatedCTM);

  if (this.options.controlIconsEnabled) {
    ControlIcons.enable(this);
  }

  // Init events handlers
  this.lastMouseWheelEventTime = Date.now();
  this.setupHandlers();
};

/**
 * Register event handlers
 */
SvgPanZoom.prototype.setupHandlers = function() {
  var that = this,
    prevEvt = null; // use for touchstart event to detect double tap

  this.eventListeners = {
    // Mouse down group
    mousedown: function(evt) {
      var result = that.handleMouseDown(evt, prevEvt);
      prevEvt = evt;
      return result;
    },
    touchstart: function(evt) {
      var result = that.handleMouseDown(evt, prevEvt);
      prevEvt = evt;
      return result;
    },

    // Mouse up group
    mouseup: function(evt) {
      return that.handleMouseUp(evt);
    },
    touchend: function(evt) {
      return that.handleMouseUp(evt);
    },

    // Mouse move group
    mousemove: function(evt) {
      return that.handleMouseMove(evt);
    },
    touchmove: function(evt) {
      return that.handleMouseMove(evt);
    },

    // Mouse leave group
    mouseleave: function(evt) {
      return that.handleMouseUp(evt);
    },
    touchleave: function(evt) {
      return that.handleMouseUp(evt);
    },
    touchcancel: function(evt) {
      return that.handleMouseUp(evt);
    }
  };

  // Init custom events handler if available
  // eslint-disable-next-line eqeqeq
  if (this.options.customEventsHandler != null) {
    this.options.customEventsHandler.init({
      svgElement: this.svg,
      eventsListenerElement: this.options.eventsListenerElement,
      instance: this.getPublicInstance()
    });

    // Custom event handler may halt builtin listeners
    var haltEventListeners = this.options.customEventsHandler
      .haltEventListeners;
    if (haltEventListeners && haltEventListeners.length) {
      for (var i = haltEventListeners.length - 1; i >= 0; i--) {
        if (this.eventListeners.hasOwnProperty(haltEventListeners[i])) {
          delete this.eventListeners[haltEventListeners[i]];
        }
      }
    }
  }

  // Bind eventListeners
  for (var event in this.eventListeners) {
    // Attach event to eventsListenerElement or SVG if not available
    (this.options.eventsListenerElement || this.svg).addEventListener(
      event,
      this.eventListeners[event],
      !this.options.preventMouseEventsDefault ? passiveListenerOption : false
    );
  }

  // Zoom using mouse wheel
  if (this.options.mouseWheelZoomEnabled) {
    this.options.mouseWheelZoomEnabled = false; // set to false as enable will set it back to true
    this.enableMouseWheelZoom();
  }
};

/**
 * Enable ability to zoom using mouse wheel
 */
SvgPanZoom.prototype.enableMouseWheelZoom = function() {
  if (!this.options.mouseWheelZoomEnabled) {
    var that = this;

    // Mouse wheel listener
    this.wheelListener = function(evt) {
      return that.handleMouseWheel(evt);
    };

    // Bind wheelListener
    var isPassiveListener = !this.options.preventMouseEventsDefault;
    Wheel.on(
      this.options.eventsListenerElement || this.svg,
      this.wheelListener,
      isPassiveListener
    );

    this.options.mouseWheelZoomEnabled = true;
  }
};

/**
 * Disable ability to zoom using mouse wheel
 */
SvgPanZoom.prototype.disableMouseWheelZoom = function() {
  if (this.options.mouseWheelZoomEnabled) {
    var isPassiveListener = !this.options.preventMouseEventsDefault;
    Wheel.off(
      this.options.eventsListenerElement || this.svg,
      this.wheelListener,
      isPassiveListener
    );
    this.options.mouseWheelZoomEnabled = false;
  }
};

/**
 * Handle mouse wheel event
 *
 * @param  {Event} evt
 */
SvgPanZoom.prototype.handleMouseWheel = function(evt) {
  if (!this.options.zoomEnabled || this.state !== "none") {
    return;
  }

  if (this.options.preventMouseEventsDefault) {
    if (evt.preventDefault) {
      evt.preventDefault();
    } else {
      evt.returnValue = false;
    }
  }

  if (this.options.onlyMouseWheel && !evt.ctrlKey) {
    return;
  }

  // Default delta in case that deltaY is not available
  var delta = evt.deltaY || 1,
    timeDelta = Date.now() - this.lastMouseWheelEventTime,
    divider = 3 + Math.max(0, 30 - timeDelta);

  // Update cache
  this.lastMouseWheelEventTime = Date.now();

  // Make empirical adjustments for browsers that give deltaY in pixels (deltaMode=0)
  if ("deltaMode" in evt && evt.deltaMode === 0 && evt.wheelDelta) {
    delta = evt.deltaY === 0 ? 0 : Math.abs(evt.wheelDelta) / evt.deltaY;
  }

  delta =
    -0.3 < delta && delta < 0.3
      ? delta
      : ((delta > 0 ? 1 : -1) * Math.log(Math.abs(delta) + 10)) / divider;

  var inversedScreenCTM = this.svg.getScreenCTM().inverse(),
    relativeMousePoint = SvgUtils.getEventPoint(evt, this.svg).matrixTransform(
      inversedScreenCTM
    ),
    zoom = Math.pow(1 + this.options.zoomScaleSensitivity, -1 * delta); // multiplying by neg. 1 so as to make zoom in/out behavior match Google maps behavior

  this.zoomAtPoint(zoom, relativeMousePoint);
};

/**
 * Zoom in at a SVG point
 *
 * @param  {SVGPoint} point
 * @param  {Float} zoomScale    Number representing how much to zoom
 * @param  {Boolean} zoomAbsolute Default false. If true, zoomScale is treated as an absolute value.
 *                                Otherwise, zoomScale is treated as a multiplied (e.g. 1.10 would zoom in 10%)
 */
SvgPanZoom.prototype.zoomAtPoint = function(zoomScale, point, zoomAbsolute) {
  var originalState = this.viewport.getOriginalState();

  if (!zoomAbsolute) {
    // Fit zoomScale in set bounds
    if (
      this.getZoom() * zoomScale <
      this.options.minZoom * originalState.zoom
    ) {
      zoomScale = (this.options.minZoom * originalState.zoom) / this.getZoom();
    } else if (
      this.getZoom() * zoomScale >
      this.options.maxZoom * originalState.zoom
    ) {
      zoomScale = (this.options.maxZoom * originalState.zoom) / this.getZoom();
    }
  } else {
    // Fit zoomScale in set bounds
    zoomScale = Math.max(
      this.options.minZoom * originalState.zoom,
      Math.min(this.options.maxZoom * originalState.zoom, zoomScale)
    );
    // Find relative scale to achieve desired scale
    zoomScale = zoomScale / this.getZoom();
  }

  var oldCTM = this.viewport.getCTM(),
    relativePoint = point.matrixTransform(oldCTM.inverse()),
    modifier = this.svg
      .createSVGMatrix()
      .translate(relativePoint.x, relativePoint.y)
      .scale(zoomScale)
      .translate(-relativePoint.x, -relativePoint.y),
    newCTM = oldCTM.multiply(modifier);

  if (newCTM.a !== oldCTM.a) {
    this.viewport.setCTM(newCTM);
  }
};

/**
 * Zoom at center point
 *
 * @param  {Float} scale
 * @param  {Boolean} absolute Marks zoom scale as relative or absolute
 */
SvgPanZoom.prototype.zoom = function(scale, absolute) {
  this.zoomAtPoint(
    scale,
    SvgUtils.getSvgCenterPoint(this.svg, this.width, this.height),
    absolute
  );
};

/**
 * Zoom used by public instance
 *
 * @param  {Float} scale
 * @param  {Boolean} absolute Marks zoom scale as relative or absolute
 */
SvgPanZoom.prototype.publicZoom = function(scale, absolute) {
  if (absolute) {
    scale = this.computeFromRelativeZoom(scale);
  }

  this.zoom(scale, absolute);
};

/**
 * Zoom at point used by public instance
 *
 * @param  {Float} scale
 * @param  {SVGPoint|Object} point    An object that has x and y attributes
 * @param  {Boolean} absolute Marks zoom scale as relative or absolute
 */
SvgPanZoom.prototype.publicZoomAtPoint = function(scale, point, absolute) {
  if (absolute) {
    // Transform zoom into a relative value
    scale = this.computeFromRelativeZoom(scale);
  }

  // If not a SVGPoint but has x and y then create a SVGPoint
  if (Utils.getType(point) !== "SVGPoint") {
    if ("x" in point && "y" in point) {
      point = SvgUtils.createSVGPoint(this.svg, point.x, point.y);
    } else {
      throw new Error("Given point is invalid");
    }
  }

  this.zoomAtPoint(scale, point, absolute);
};

/**
 * Get zoom scale
 *
 * @return {Float} zoom scale
 */
SvgPanZoom.prototype.getZoom = function() {
  return this.viewport.getZoom();
};

/**
 * Get zoom scale for public usage
 *
 * @return {Float} zoom scale
 */
SvgPanZoom.prototype.getRelativeZoom = function() {
  return this.viewport.getRelativeZoom();
};

/**
 * Compute actual zoom from public zoom
 *
 * @param  {Float} zoom
 * @return {Float} zoom scale
 */
SvgPanZoom.prototype.computeFromRelativeZoom = function(zoom) {
  return zoom * this.viewport.getOriginalState().zoom;
};

/**
 * Set zoom to initial state
 */
SvgPanZoom.prototype.resetZoom = function() {
  var originalState = this.viewport.getOriginalState();

  this.zoom(originalState.zoom, true);
};

/**
 * Set pan to initial state
 */
SvgPanZoom.prototype.resetPan = function() {
  this.pan(this.viewport.getOriginalState());
};

/**
 * Set pan and zoom to initial state
 */
SvgPanZoom.prototype.reset = function() {
  this.resetZoom();
  this.resetPan();
};

/**
 * Handle double click event
 * See handleMouseDown() for alternate detection method
 *
 * @param {Event} evt
 */
SvgPanZoom.prototype.handleDblClick = function(evt) {
  if (this.options.preventMouseEventsDefault) {
    if (evt.preventDefault) {
      evt.preventDefault();
    } else {
      evt.returnValue = false;
    }
  }

  // Check if target was a control button
  if (this.options.controlIconsEnabled) {
    var targetClass = evt.target.getAttribute("class") || "";
    if (targetClass.indexOf("svg-pan-zoom-control") > -1) {
      return false;
    }
  }

  var zoomFactor;

  if (evt.shiftKey) {
    zoomFactor = 1 / ((1 + this.options.zoomScaleSensitivity) * 2); // zoom out when shift key pressed
  } else {
    zoomFactor = (1 + this.options.zoomScaleSensitivity) * 2;
  }

  var point = SvgUtils.getEventPoint(evt, this.svg).matrixTransform(
    this.svg.getScreenCTM().inverse()
  );
  this.zoomAtPoint(zoomFactor, point);
};

/**
 * Handle click event
 *
 * @param {Event} evt
 */
SvgPanZoom.prototype.handleMouseDown = function(evt, prevEvt) {
  if (this.options.preventMouseEventsDefault) {
    if (evt.preventDefault) {
      evt.preventDefault();
    } else {
      evt.returnValue = false;
    }
  }

  Utils.mouseAndTouchNormalize(evt, this.svg);

  // Double click detection; more consistent than ondblclick
  if (this.options.dblClickZoomEnabled && Utils.isDblClick(evt, prevEvt)) {
    this.handleDblClick(evt);
  } else {
    // Pan mode
    this.state = "pan";
    this.firstEventCTM = this.viewport.getCTM();
    this.stateOrigin = SvgUtils.getEventPoint(evt, this.svg).matrixTransform(
      this.firstEventCTM.inverse()
    );
  }
};

/**
 * Handle mouse move event
 *
 * @param  {Event} evt
 */
SvgPanZoom.prototype.handleMouseMove = function(evt) {
  if (this.options.preventMouseEventsDefault) {
    if (evt.preventDefault) {
      evt.preventDefault();
    } else {
      evt.returnValue = false;
    }
  }

  if (this.state === "pan" && this.options.panEnabled) {
    // Pan mode
    var point = SvgUtils.getEventPoint(evt, this.svg).matrixTransform(
        this.firstEventCTM.inverse()
      ),
      viewportCTM = this.firstEventCTM.translate(
        point.x - this.stateOrigin.x,
        point.y - this.stateOrigin.y
      );

    this.viewport.setCTM(viewportCTM);
  }
};

/**
 * Handle mouse button release event
 *
 * @param {Event} evt
 */
SvgPanZoom.prototype.handleMouseUp = function(evt) {
  if (this.options.preventMouseEventsDefault) {
    if (evt.preventDefault) {
      evt.preventDefault();
    } else {
      evt.returnValue = false;
    }
  }

  if (this.state === "pan") {
    // Quit pan mode
    this.state = "none";
  }
};

/**
 * Adjust viewport size (only) so it will fit in SVG
 * Does not center image
 */
SvgPanZoom.prototype.fit = function() {
  var viewBox = this.viewport.getViewBox(),
    newScale = Math.min(
      this.width / viewBox.width,
      this.height / viewBox.height
    );

  this.zoom(newScale, true);
};

/**
 * Adjust viewport size (only) so it will contain the SVG
 * Does not center image
 */
SvgPanZoom.prototype.contain = function() {
  var viewBox = this.viewport.getViewBox(),
    newScale = Math.max(
      this.width / viewBox.width,
      this.height / viewBox.height
    );

  this.zoom(newScale, true);
};

/**
 * Adjust viewport pan (only) so it will be centered in SVG
 * Does not zoom/fit/contain image
 */
SvgPanZoom.prototype.center = function() {
  var viewBox = this.viewport.getViewBox(),
    offsetX =
      (this.width - (viewBox.width + viewBox.x * 2) * this.getZoom()) * 0.5,
    offsetY =
      (this.height - (viewBox.height + viewBox.y * 2) * this.getZoom()) * 0.5;

  this.getPublicInstance().pan({ x: offsetX, y: offsetY });
};

/**
 * Update content cached BorderBox
 * Use when viewport contents change
 */
SvgPanZoom.prototype.updateBBox = function() {
  this.viewport.simpleViewBoxCache();
};

/**
 * Pan to a rendered position
 *
 * @param  {Object} point {x: 0, y: 0}
 */
SvgPanZoom.prototype.pan = function(point) {
  var viewportCTM = this.viewport.getCTM();
  viewportCTM.e = point.x;
  viewportCTM.f = point.y;
  this.viewport.setCTM(viewportCTM);
};

/**
 * Relatively pan the graph by a specified rendered position vector
 *
 * @param  {Object} point {x: 0, y: 0}
 */
SvgPanZoom.prototype.panBy = function(point) {
  var viewportCTM = this.viewport.getCTM();
  viewportCTM.e += point.x;
  viewportCTM.f += point.y;
  this.viewport.setCTM(viewportCTM);
};

/**
 * Get pan vector
 *
 * @return {Object} {x: 0, y: 0}
 */
SvgPanZoom.prototype.getPan = function() {
  var state = this.viewport.getState();

  return { x: state.x, y: state.y };
};

/**
 * Recalculates cached svg dimensions and controls position
 */
SvgPanZoom.prototype.resize = function() {
  // Get dimensions
  var boundingClientRectNormalized = SvgUtils.getBoundingClientRectNormalized(
    this.svg
  );
  this.width = boundingClientRectNormalized.width;
  this.height = boundingClientRectNormalized.height;

  // Recalculate original state
  var viewport = this.viewport;
  viewport.options.width = this.width;
  viewport.options.height = this.height;
  viewport.processCTM();

  // Reposition control icons by re-enabling them
  if (this.options.controlIconsEnabled) {
    this.getPublicInstance().disableControlIcons();
    this.getPublicInstance().enableControlIcons();
  }
};

/**
 * Unbind mouse events, free callbacks and destroy public instance
 */
SvgPanZoom.prototype.destroy = function() {
  var that = this;

  // Free callbacks
  this.beforeZoom = null;
  this.onZoom = null;
  this.beforePan = null;
  this.onPan = null;
  this.onUpdatedCTM = null;

  // Destroy custom event handlers
  // eslint-disable-next-line eqeqeq
  if (this.options.customEventsHandler != null) {
    this.options.customEventsHandler.destroy({
      svgElement: this.svg,
      eventsListenerElement: this.options.eventsListenerElement,
      instance: this.getPublicInstance()
    });
  }

  // Unbind eventListeners
  for (var event in this.eventListeners) {
    (this.options.eventsListenerElement || this.svg).removeEventListener(
      event,
      this.eventListeners[event],
      !this.options.preventMouseEventsDefault ? passiveListenerOption : false
    );
  }

  // Unbind wheelListener
  this.disableMouseWheelZoom();

  // Remove control icons
  this.getPublicInstance().disableControlIcons();

  // Reset zoom and pan
  this.reset();

  // Remove instance from instancesStore
  instancesStore = instancesStore.filter(function(instance) {
    return instance.svg !== that.svg;
  });

  // Delete options and its contents
  delete this.options;

  // Delete viewport to make public shadow viewport functions uncallable
  delete this.viewport;

  // Destroy public instance and rewrite getPublicInstance
  delete this.publicInstance;
  delete this.pi;
  this.getPublicInstance = function() {
    return null;
  };
};

/**
 * Returns a public instance object
 *
 * @return {Object} Public instance object
 */
SvgPanZoom.prototype.getPublicInstance = function() {
  var that = this;

  // Create cache
  if (!this.publicInstance) {
    this.publicInstance = this.pi = {
      // Pan
      enablePan: function() {
        that.options.panEnabled = true;
        return that.pi;
      },
      disablePan: function() {
        that.options.panEnabled = false;
        return that.pi;
      },
      isPanEnabled: function() {
        return !!that.options.panEnabled;
      },
      pan: function(point) {
        that.pan(point);
        return that.pi;
      },
      panBy: function(point) {
        that.panBy(point);
        return that.pi;
      },
      getPan: function() {
        return that.getPan();
      },
      // Pan event
      setBeforePan: function(fn) {
        that.options.beforePan =
          fn === null ? null : Utils.proxy(fn, that.publicInstance);
        return that.pi;
      },
      setOnPan: function(fn) {
        that.options.onPan =
          fn === null ? null : Utils.proxy(fn, that.publicInstance);
        return that.pi;
      },
      // Zoom and Control Icons
      enableZoom: function() {
        that.options.zoomEnabled = true;
        return that.pi;
      },
      disableZoom: function() {
        that.options.zoomEnabled = false;
        return that.pi;
      },
      isZoomEnabled: function() {
        return !!that.options.zoomEnabled;
      },
      enableControlIcons: function() {
        if (!that.options.controlIconsEnabled) {
          that.options.controlIconsEnabled = true;
          ControlIcons.enable(that);
        }
        return that.pi;
      },
      disableControlIcons: function() {
        if (that.options.controlIconsEnabled) {
          that.options.controlIconsEnabled = false;
          ControlIcons.disable(that);
        }
        return that.pi;
      },
      isControlIconsEnabled: function() {
        return !!that.options.controlIconsEnabled;
      },
      // Double click zoom
      enableDblClickZoom: function() {
        that.options.dblClickZoomEnabled = true;
        return that.pi;
      },
      disableDblClickZoom: function() {
        that.options.dblClickZoomEnabled = false;
        return that.pi;
      },
      isDblClickZoomEnabled: function() {
        return !!that.options.dblClickZoomEnabled;
      },
      // Mouse wheel zoom
      enableMouseWheelZoom: function() {
        that.enableMouseWheelZoom();
        return that.pi;
      },
      disableMouseWheelZoom: function() {
        that.disableMouseWheelZoom();
        return that.pi;
      },
      isMouseWheelZoomEnabled: function() {
        return !!that.options.mouseWheelZoomEnabled;
      },
      // Zoom scale and bounds
      setZoomScaleSensitivity: function(scale) {
        that.options.zoomScaleSensitivity = scale;
        return that.pi;
      },
      setMinZoom: function(zoom) {
        that.options.minZoom = zoom;
        return that.pi;
      },
      setMaxZoom: function(zoom) {
        that.options.maxZoom = zoom;
        return that.pi;
      },
      // Zoom event
      setBeforeZoom: function(fn) {
        that.options.beforeZoom =
          fn === null ? null : Utils.proxy(fn, that.publicInstance);
        return that.pi;
      },
      setOnZoom: function(fn) {
        that.options.onZoom =
          fn === null ? null : Utils.proxy(fn, that.publicInstance);
        return that.pi;
      },
      // Zooming
      zoom: function(scale) {
        that.publicZoom(scale, true);
        return that.pi;
      },
      zoomBy: function(scale) {
        that.publicZoom(scale, false);
        return that.pi;
      },
      zoomAtPoint: function(scale, point) {
        that.publicZoomAtPoint(scale, point, true);
        return that.pi;
      },
      zoomAtPointBy: function(scale, point) {
        that.publicZoomAtPoint(scale, point, false);
        return that.pi;
      },
      zoomIn: function() {
        this.zoomBy(1 + that.options.zoomScaleSensitivity);
        return that.pi;
      },
      zoomOut: function() {
        this.zoomBy(1 / (1 + that.options.zoomScaleSensitivity));
        return that.pi;
      },
      getZoom: function() {
        return that.getRelativeZoom();
      },
      // CTM update
      setOnUpdatedCTM: function(fn) {
        that.options.onUpdatedCTM =
          fn === null ? null : Utils.proxy(fn, that.publicInstance);
        return that.pi;
      },
      // Reset
      resetZoom: function() {
        that.resetZoom();
        return that.pi;
      },
      resetPan: function() {
        that.resetPan();
        return that.pi;
      },
      reset: function() {
        that.reset();
        return that.pi;
      },
      // Fit, Contain and Center
      fit: function() {
        that.fit();
        return that.pi;
      },
      contain: function() {
        that.contain();
        return that.pi;
      },
      center: function() {
        that.center();
        return that.pi;
      },
      // Size and Resize
      updateBBox: function() {
        that.updateBBox();
        return that.pi;
      },
      resize: function() {
        that.resize();
        return that.pi;
      },
      getSizes: function() {
        return {
          width: that.width,
          height: that.height,
          realZoom: that.getZoom(),
          viewBox: that.viewport.getViewBox()
        };
      },
      // Destroy
      destroy: function() {
        that.destroy();
        return that.pi;
      }
    };
  }

  return this.publicInstance;
};

/**
 * Stores pairs of instances of SvgPanZoom and SVG
 * Each pair is represented by an object {svg: SVGSVGElement, instance: SvgPanZoom}
 *
 * @type {Array}
 */
var instancesStore = [];

var svgPanZoom = function(elementOrSelector, options) {
  var svg = Utils.getSvg(elementOrSelector);

  if (svg === null) {
    return null;
  } else {
    // Look for existent instance
    for (var i = instancesStore.length - 1; i >= 0; i--) {
      if (instancesStore[i].svg === svg) {
        return instancesStore[i].instance.getPublicInstance();
      }
    }

    // If instance not found - create one
    instancesStore.push({
      svg: svg,
      instance: new SvgPanZoom(svg, options)
    });

    // Return just pushed instance
    return instancesStore[
      instancesStore.length - 1
    ].instance.getPublicInstance();
  }
};

module.exports = svgPanZoom;