hammer.js實現移動端的圖片手勢放大功能

 var reqAnimationFrame = (function() {
 return window[Hammer.prefixed(window, 'requestAnimationFrame')] || function(callback) {
 window.setTimeout(callback, 1000 / 60);
 };
 })();
 var el = $('img');
 var ticking = false;
 var transform;
 var initScale = 1;
 var _eImg = '';
 for (var m = 0; m < el.length; m++) {
 var mc = new Hammer.Manager(el[m]);
 mc.add(new Hammer.Pan({
 threshold: 0,
 pointers: 0
 }));
 mc.add(new Hammer.Swipe()).recognizeWith(mc.get('pan'));
 mc.add(new Hammer.Pinch({
 threshold: 0
 })).recognizeWith(mc.get('pan'));
 mc.on('panstart panmove', onPan);
 mc.on('pinchstart pinchmove', onPinch);
 mc.on('swipe', onSwipe);
 }
 
 function resetElement() {
 el.addClass('animate');
 transform = {
 translate: {
 x: 0,
 y: 0
 },
 scale: 1,
 angle: 0,
 rx: 0,
 ry: 0,
 rz: 0
 };
 requestElementUpdate();
 }
 
 function updateElementTransform() {
 var value = ['translate3d(' + transform.translate.x + 'px, ' + transform.translate.y + 'px, 0)', 'scale(' + transform.scale + ', ' + transform.scale + ')', 'rotate3d(' + transform.rx + ',' + transform.ry + ',' + transform.rz + ',' + transform.angle + 'deg)'];
 value = value.join(' ');
 if (_eImg != '') {
 _eImg.style.webkitTransform = value;
 _eImg.style.mozTransform = value;
 _eImg.style.transform = value;
 //_eImg.css({ 'transform': value }, { '-webkit-transform': value });
 }
 ticking = false;
 }
 
 function requestElementUpdate() {
 if (!ticking) {
 reqAnimationFrame(updateElementTransform);
 ticking = true;
 }
 }
 
 function onPan(ev) {
 el.removeClass('animate');
 transform.translate = {
 x: ev.deltaX,
 y: ev.deltaY
 };
 }
 
 function onPinch(ev) {
 if (ev.type == 'pinchstart') {
 initScale = transform.scale || 1;
 }
 el.removeClass('animate');
 transform.scale = initScale * ev.scale;
 requestElementUpdate();
 _eImg = ev.target;
 return _eImg;
 }
 
 function onSwipe(ev) {
 var angle = 10;
 transform.ry = (ev.direction & Hammer.DIRECTION_HORIZONTAL) ? 1 : 0;
 transform.rx = (ev.direction & Hammer.DIRECTION_VERTICAL) ? 1 : 0;
 transform.angle = (ev.direction & (Hammer.DIRECTION_RIGHT | Hammer.DIRECTION_UP)) ? angle : -angle;
 requestElementUpdate();
 _eImg = ev.target;
 return _eImg;
 }
 resetElement();