// Generated by CoffeeScript 1.10.0

/* (C) 2015 Narazaka : Licensed under The MIT License - http://narazaka.net/license/MIT?2015 */

(function() {
  var computed_styles, num2px, page_offset, px2num, wheelevent, wheelzoom;

  px2num = function(px) {
    return px.substr(0, px.length - 2) - 0;
  };

  num2px = function(num) {
    return num + 'px';
  };

  computed_styles = function(element) {
    var base;
    return typeof (base = document.defaultView || window).getComputedStyle === "function" ? base.getComputedStyle(element, null) : void 0;
  };

  page_offset = function(element) {
    var box, docElem, win;
    docElem = element.ownerDocument.documentElement;
    box = element.getBoundingClientRect();
    win = document.defaultView || element.parentWindow || window;
    return {
      top: box.top + (win.pageYOffset || docElem.scrollTop) - (docElem.clientTop || 0),
      left: box.left + (win.pageXOffset || docElem.scrollLeft) - (docElem.clientLeft || 0)
    };
  };

  wheelevent = this.wheelevent;

  wheelzoom = function(target, parent) {
    var handler;
    if (parent == null) {
      parent = target.parentNode;
    }
    target.style.position = 'relative';
    target.style.left = '0px';
    target.style.top = '0px';
    target.setAttribute('data-wheelzoom-scale-factor', 0);
    handler = function(event, delta) {
      var height, left, mouse_x, mouse_y, offset, old_height, old_left, old_scale, old_scale_factor, old_target_styles, old_top, old_width, scale, scale_delta, scale_factor, top, width;
      old_scale_factor = target.getAttribute('data-wheelzoom-scale-factor') - 0;
      scale_factor = old_scale_factor + (Math.abs(delta) > 80 ? delta / 1000 : delta / 30);
      old_scale = Math.exp(old_scale_factor);
      scale = Math.exp(scale_factor);
      old_left = px2num(target.style.left);
      old_top = px2num(target.style.top);
      old_width = target.clientWidth;
      old_height = target.clientHeight;
      if (!old_width) {
        old_target_styles = computed_styles(target);
        old_width = px2num(old_target_styles.width);
        old_height = px2num(old_target_styles.height);
      }
      offset = page_offset(parent);
      mouse_x = (event.clientX || window.event.clientX) + parent.ownerDocument.documentElement.scrollLeft - offset.left;
      mouse_y = (event.clientY || window.event.clientY) + parent.ownerDocument.documentElement.scrollTop - offset.top;
      scale_delta = scale / old_scale;
      left = mouse_x - (mouse_x - old_left) * scale_delta;
      top = mouse_y - (mouse_y - old_top) * scale_delta;
      width = old_width * scale_delta;
      height = old_height * scale_delta;
      target.style.width = num2px(width);
      target.style.height = num2px(height);
      target.style.left = num2px(left);
      target.style.top = num2px(top);
      target.setAttribute('data-wheelzoom-scale-factor', scale_factor);
      if (typeof event.preventDefault === "function") {
        event.preventDefault();
      }
      return false;
    };
    return wheelevent(parent, handler);
  };

  this.wheelzoom = wheelzoom;

}).call(this);