Image zoom

image-zoom.markdown

Image zoom

Magnifying glass like effect

A Pen by Balázs Suhajda on CodePen.

License.

index.html

  <img height="750" src="http://farm6.staticflickr.com/5474/9765019294_91f9710e92_b_d.jpg"/>
  <div id="zoom"></div>

script.js

(function() {
  var zoom = document.getElementById( 'zoom' ),
      Zw = zoom.offsetWidth,
      Zh = zoom.offsetHeight,
      img = document.querySelector( 'img' );
      
  
  var timeout, ratio, Ix, Iy;

  function activate () {
    document.body.classList.add( 'active' );
  }
  
  function deactivate() {
    document.body.classList.remove( 'active' );
  }
  
  function updateMagnifier( x, y ) {
    zoom.style.top = ( y ) + 'px';
    zoom.style.left = ( x ) + 'px';
    zoom.style.backgroundPosition = (( Ix - x ) * ratio + Zw / 2 ) + 'px ' + (( Iy - y ) * ratio + Zh / 2 ) + 'px';
  }
  
  function onLoad () {
    ratio = img.naturalWidth / img.width;
    zoom.style.backgroundImage = 'url(' + img.src + ')';
    Ix = img.offsetLeft;
    Iy = img.offsetTop;
  }
  
  function onMousemove( e ) {
    clearTimeout( timeout );
    activate();
    updateMagnifier( e.x, e.y );
    timeout = setTimeout( deactivate, 2500 );
  }
  
  function onMouseleave () {
    deactivate();
  }

  img.addEventListener( 'load', onLoad );
  img.addEventListener( 'mousemove', onMousemove );
  img.addEventListener( 'mouseleave', onMouseleave );

})();

style.css

body {
  overflow: hidden;
  margin: 0;
  
  background: #222;
}

body.active img {
  -webkit-filter: grayscale(1);
}

img {
  display: block;
  margin: 20px auto;
  
  border: 1px solid rgba(255,255,255,0.2);
  -webkit-transition: -webkit-filter 500ms;
}

#zoom {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 250px;
  height: 250px;
  margin: -125px 0 0 -125px;
  background-repeat: no-repeat;
  box-shadow: 0 0 0 2px rgba(255,0,0,0.5),
    5px 5px 10px 5px rgba(0,0,0,0.2);
  border-radius: 50%;
  opacity: 0;
  -webkit-transform: scale(0);
  -webkit-transition: opacity 500ms, -webkit-transform 500ms;
  pointer-events: none;
}

.active #zoom {
  opacity: 1;
  -webkit-transform: scale(1);
}

This looks really cool, thanks for the effort!
Do you think this could be adjusted to using the magnifying glass on a div element that contains multiple images?