d2-ui/node_modules-react-15/react-tap-event-plugin/src/TapEventPlugin.js

d2-ui

/**
 * Copyright 2013-2014 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @providesModule TapEventPlugin
 * @typechecks static-only
 */

"use strict";

var EventConstants = require('react/lib/EventConstants');
var EventPluginUtils = require('react/lib/EventPluginUtils');
var EventPropagators = require('react/lib/EventPropagators');
var SyntheticUIEvent = require('react/lib/SyntheticUIEvent');
var TouchEventUtils = require('./TouchEventUtils');
var ViewportMetrics = require('react/lib/ViewportMetrics');

var keyOf = require('fbjs/lib/keyOf');
var topLevelTypes = EventConstants.topLevelTypes;

var isStartish = EventPluginUtils.isStartish;
var isEndish = EventPluginUtils.isEndish;

var isTouch = function(topLevelType) {
  var touchTypes = [
    topLevelTypes.topTouchCancel,
    topLevelTypes.topTouchEnd,
    topLevelTypes.topTouchStart,
    topLevelTypes.topTouchMove
  ];
  return touchTypes.indexOf(topLevelType) >= 0;
}

/**
 * Number of pixels that are tolerated in between a `touchStart` and `touchEnd`
 * in order to still be considered a 'tap' event.
 */
var tapMoveThreshold = 10;
var ignoreMouseThreshold = 750;
var startCoords = {x: null, y: null};
var lastTouchEvent = null;

var Axis = {
  x: {page: 'pageX', client: 'clientX', envScroll: 'currentPageScrollLeft'},
  y: {page: 'pageY', client: 'clientY', envScroll: 'currentPageScrollTop'}
};

function getAxisCoordOfEvent(axis, nativeEvent) {
  var singleTouch = TouchEventUtils.extractSingleTouch(nativeEvent);
  if (singleTouch) {
    return singleTouch[axis.page];
  }
  return axis.page in nativeEvent ?
    nativeEvent[axis.page] :
    nativeEvent[axis.client] + ViewportMetrics[axis.envScroll];
}

function getDistance(coords, nativeEvent) {
  var pageX = getAxisCoordOfEvent(Axis.x, nativeEvent);
  var pageY = getAxisCoordOfEvent(Axis.y, nativeEvent);
  return Math.pow(
    Math.pow(pageX - coords.x, 2) + Math.pow(pageY - coords.y, 2),
    0.5
  );
}

var touchEvents = [
  topLevelTypes.topTouchStart,
  topLevelTypes.topTouchCancel,
  topLevelTypes.topTouchEnd,
  topLevelTypes.topTouchMove,
];

var dependencies = [
  topLevelTypes.topMouseDown,
  topLevelTypes.topMouseMove,
  topLevelTypes.topMouseUp,
].concat(touchEvents);

var eventTypes = {
  touchTap: {
    phasedRegistrationNames: {
      bubbled: keyOf({onTouchTap: null}),
      captured: keyOf({onTouchTapCapture: null})
    },
    dependencies: dependencies
  }
};

var now = (function() {
  if (Date.now) {
    return Date.now;
  } else {
    // IE8 support: http://stackoverflow.com/questions/9430357/please-explain-why-and-how-new-date-works-as-workaround-for-date-now-in
    return function () {
      return +new Date;
    }
  }
})();

function createTapEventPlugin(shouldRejectClick) {
  return {

    tapMoveThreshold: tapMoveThreshold,

    ignoreMouseThreshold: ignoreMouseThreshold,

    eventTypes: eventTypes,

    /**
     * @param {string} topLevelType Record from `EventConstants`.
     * @param {DOMEventTarget} targetInst The listening component root node.
     * @param {object} nativeEvent Native browser event.
     * @return {*} An accumulation of synthetic events.
     * @see {EventPluginHub.extractEvents}
     */
    extractEvents: function(
      topLevelType,
      targetInst,
      nativeEvent,
      nativeEventTarget
    ) {

      if (isTouch(topLevelType)) {
        lastTouchEvent = now();
      } else {
        if (shouldRejectClick(lastTouchEvent, now())) {
          return null;
        }
      }

      if (!isStartish(topLevelType) && !isEndish(topLevelType)) {
        return null;
      }
      var event = null;
      var distance = getDistance(startCoords, nativeEvent);
      if (isEndish(topLevelType) && distance < tapMoveThreshold) {
        event = SyntheticUIEvent.getPooled(
          eventTypes.touchTap,
          targetInst,
          nativeEvent,
          nativeEventTarget
        );
      }
      if (isStartish(topLevelType)) {
        startCoords.x = getAxisCoordOfEvent(Axis.x, nativeEvent);
        startCoords.y = getAxisCoordOfEvent(Axis.y, nativeEvent);
      } else if (isEndish(topLevelType)) {
        startCoords.x = 0;
        startCoords.y = 0;
      }
      EventPropagators.accumulateTwoPhaseDispatches(event);
      return event;
    }

  };
}

module.exports = createTapEventPlugin;