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// Copyright 2013 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview Utilities to abstract mouse and touch events.
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 */
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goog.provide('goog.labs.events.touch');
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goog.provide('goog.labs.events.touch.TouchData');
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goog.require('goog.array');
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goog.require('goog.asserts');
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goog.require('goog.events.EventType');
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goog.require('goog.string');
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/**
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 * Description the geometry and target of an event.
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 *
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 * @typedef {{
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 *   clientX: number,
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 *   clientY: number,
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 *   screenX: number,
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 *   screenY: number,
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 *   target: EventTarget
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 * }}
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 */
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goog.labs.events.touch.TouchData;
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/**
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 * Takes a mouse or touch event and returns the relevant geometry and target
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 * data.
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 * @param {!Event} e A mouse or touch event.
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 * @return {!goog.labs.events.touch.TouchData}
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 */
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goog.labs.events.touch.getTouchData = function(e) {
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  var source = e;
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  goog.asserts.assert(
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      goog.string.startsWith(e.type, 'touch') ||
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          goog.string.startsWith(e.type, 'mouse'),
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      'Event must be mouse or touch event.');
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  if (goog.string.startsWith(e.type, 'touch')) {
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    goog.asserts.assert(
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        goog.array.contains(
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            [
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              goog.events.EventType.TOUCHCANCEL, goog.events.EventType.TOUCHEND,
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              goog.events.EventType.TOUCHMOVE, goog.events.EventType.TOUCHSTART
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            ],
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            e.type),
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        'Touch event not of valid type.');
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    // If the event is end or cancel, take the first changed touch,
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    // otherwise the first target touch.
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    source = (e.type == goog.events.EventType.TOUCHEND ||
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              e.type == goog.events.EventType.TOUCHCANCEL) ?
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        e.changedTouches[0] :
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        e.targetTouches[0];
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  }
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  return {
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    clientX: source['clientX'],
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    clientY: source['clientY'],
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    screenX: source['screenX'],
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    screenY: source['screenY'],
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    target: source['target']
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  };
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};
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