Auto scroll div based on mouse position

Question

I want to automatically scroll a div based on mouse position using jQuery.

If you see this fiddle here, you can see a number of images that are horizontally ordered in a div that is scrollable:

<div id="parent">
    <div id="propertyThumbnails">
        <img src="http://www.millport.org/wp-content/uploads/2013/05/Flower-festival.jpg" />
        <img src="http://www.millport.org/wp-content/uploads/2013/05/Flower-festival.jpg" />
        <img src="http://www.millport.org/wp-content/uploads/2013/05/Flower-festival.jpg" />
        <img src="http://www.millport.org/wp-content/uploads/2013/05/Flower-festival.jpg" />
        <img src="http://www.millport.org/wp-content/uploads/2013/05/Flower-festival.jpg" />
    </div>
</div>

CSS:

#parent {
    height: 300px;
    width: 100%;
    background: #ddd;
}
#propertyThumbnails {
    background: #666;
    height: 80px;
    white-space: nowrap;
    overflow: scroll;
}
#propertyThumbnails img {
    width: 125px;
    height: 80px;
    display: inline-block;
    margin: 3px;
    margin-right: 0;
    opacity: 0.6; 
}

I found out that you can use $("#container").scrollLeft(position) to set the position of the scroller but I want to do it based on the mouse position of the parent. So that when the mouse is fully to the right hand side, the right most image displays, and when the mouse is fully left, the left most image displays.

How can I do this?

Answer 1

A slightly different way to achieve what you need:

jQuery(function($) {

  $(window).load(function() {

    var $gal = $("#propertyThumbnails"),
      galW = $gal.outerWidth(true),
      galSW = $gal[0].scrollWidth,
      wDiff = (galSW / galW) - 1, // widths difference ratio
      mPadd = 60, // Mousemove Padding
      damp = 20, // Mousemove response softness
      mX = 0, // Real mouse position
      mX2 = 0, // Modified mouse position
      posX = 0,
      mmAA = galW - (mPadd * 2), // The mousemove available area
      mmAAr = (galW / mmAA); // get available mousemove fidderence ratio

    $gal.mousemove(function(e) {
      mX = e.pageX - $(this).offset().left;
      mX2 = Math.min(Math.max(0, mX - mPadd), mmAA) * mmAAr;
    });

    setInterval(function() {
      posX += (mX2 - posX) / damp; // zeno's paradox equation "catching delay"	
      $gal.scrollLeft(posX * wDiff);
    }, 10);

  });

});

#parent {
  position: relative;
  margin: 0 auto;
  width: 60%;
  height: 260px;
}

#propertyThumbnails {
  position: relative;
  overflow: hidden;
  background: #444;
  width: 100%;
  height: 262px;
  white-space: nowrap;
}

#propertyThumbnails img {
  vertical-align: middle;
  height: 100%;
  display: inline;
  margin-left: -4px;
}

<div id="parent">
  <div id="propertyThumbnails">

    <img src="//placehold.it/600x400/0bf" />
    <img src="//placehold.it/600x400/f0b" />
    <img src="//placehold.it/600x400/0fb" />
    <img src="//placehold.it/600x400/b0f" />
    <img src="//placehold.it/600x400/bf0" />

  </div>
</div>


<script src="//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

where mPadd is the area (in PX, at the left and right border zone) without any sensitivity to prevent user frustrations :)