/**
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* Only implements needed gestures for mobile.
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*/
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import * as eventUtil from './event';
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var GestureMgr = function () {
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/**
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* @private
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* @type {Array.<Object>}
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*/
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this._track = [];
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};
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GestureMgr.prototype = {
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constructor: GestureMgr,
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recognize: function (event, target, root) {
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this._doTrack(event, target, root);
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return this._recognize(event);
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},
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clear: function () {
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this._track.length = 0;
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return this;
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},
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_doTrack: function (event, target, root) {
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var touches = event.touches;
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if (!touches) {
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return;
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}
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var trackItem = {
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points: [],
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touches: [],
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target: target,
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event: event
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};
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for (var i = 0, len = touches.length; i < len; i++) {
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var touch = touches[i];
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var pos = eventUtil.clientToLocal(root, touch, {});
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trackItem.points.push([pos.zrX, pos.zrY]);
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trackItem.touches.push(touch);
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}
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this._track.push(trackItem);
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},
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_recognize: function (event) {
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for (var eventName in recognizers) {
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if (recognizers.hasOwnProperty(eventName)) {
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var gestureInfo = recognizers[eventName](this._track, event);
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if (gestureInfo) {
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return gestureInfo;
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}
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}
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}
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}
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};
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function dist(pointPair) {
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var dx = pointPair[1][0] - pointPair[0][0];
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var dy = pointPair[1][1] - pointPair[0][1];
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return Math.sqrt(dx * dx + dy * dy);
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}
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function center(pointPair) {
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return [
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(pointPair[0][0] + pointPair[1][0]) / 2,
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(pointPair[0][1] + pointPair[1][1]) / 2
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];
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}
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var recognizers = {
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pinch: function (track, event) {
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var trackLen = track.length;
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if (!trackLen) {
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return;
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}
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var pinchEnd = (track[trackLen - 1] || {}).points;
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var pinchPre = (track[trackLen - 2] || {}).points || pinchEnd;
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if (pinchPre
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&& pinchPre.length > 1
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&& pinchEnd
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&& pinchEnd.length > 1
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) {
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var pinchScale = dist(pinchEnd) / dist(pinchPre);
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!isFinite(pinchScale) && (pinchScale = 1);
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event.pinchScale = pinchScale;
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var pinchCenter = center(pinchEnd);
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event.pinchX = pinchCenter[0];
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event.pinchY = pinchCenter[1];
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return {
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type: 'pinch',
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target: track[0].target,
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event: event
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};
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}
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}
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// Only pinch currently.
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};
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export default GestureMgr;
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