hammer.js实现图片手势放大效果

 //图片手势放大
      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();