zoom image filling screen

by ozzan

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="loader">Loading</div>
<div id="zoom"></div>

CSS

#zoom {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1000000;
    display: none;
}

#zoom img {
    width: 200%;
    height: 100%;
    height: auto;
    position: absolute;
    cursor: crosshair;
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

body {
    margin: 0;
}

* {
    box-sizing: border-box;
}

JavaScript

var Zoom = function(imageZoom) {
  this.urlImage = imageZoom;
  this.img = undefined;
  this.$img = undefined;

  this.init = function() {
    this.loaders("on");
    this.calcs();
  };
  this.calcs = function() {
    var self = this;
    this.img = new Image();
    this.img.onload = function() {
      self.build();
    };
    this.img.src = this.urlImage;
  };
  this.loaders = function(status) {
    switch (status) {
      case "on":
        $('#loader').fadeIn(200);
        break;
      case "off":
        $('#loader').fadeOut(200);
        break;
    }
  };
  this.build = function() {
    var self = this;
    this.$img = $(self.img);

    $('#zoom').fadeIn(200).append(this.$img);

    this.$img.on('mousedown', function(e) {
      e.preventDefault();
    });

    // this is the problematic function
    $('body').on('mousemove', function(e) {
      e.preventDefault();

      var wx = $(window).width();
      var wy = $(window).height();
      var iy = self.$img.height();

      var px = e.pageX;
      var py = e.pageY;

      var tx = -1 * (px / wx) * wx;
      var ty = -1 * (py / wy) * (iy - wy);

      self.$img.css({
        'transform': 'translate(' + tx + 'px, ' + ty + 'px)'
      });
    });
    self.loaders("off");
  };
};

var zoom = new Zoom("http://dummyimage.com/4200x900/000/fff");
//var zoom = new Zoom("http://192.163.220.111/~amonarra/_beta/uploads/img1_zoom.jpg");
zoom.init();