Image Navigator

Steve Chipman Aug 13, 2008

General

This script works by sliding the background image of one DIV element, using the background-position to correspond with the coordinates of another DIV. Great for showing details in a small space.

Click and drag the red outlined square on the bottom photo to navigate the zoomed image.

Notes

Created by: Steve Chipman
Web Site: http://slayeroffice

Source Code

Paste this source code into the designated areas.

External file

Paste this code into an external JavaScript file named: imageNavigator.js

/* This script and many more are available free online at
The JavaScript Source!! http://www.javascriptsource.com
Created by: Steve Chipman | http://slayeroffice */

var mDown = false;
var offsetX=0;
var offsetY=0;
function init() {
	document.onmousedown = captureMouseDown;
	document.onmousemove = captureMouseMove;
	document.onmouseup = captureMouseUp;
	document.getElementById("marker").onmousedown = captureOffset;
	document.getElementById("marker").style.top = "0px";
	document.getElementById("marker").style.left = "0px";
}

function captureOffset(e) {
	x = parseInt(document.getElementById("marker").style.left);
	y = parseInt(document.getElementById("marker").style.top);
	if(document.all) {
		offsetX=window.event.clientX - x;
		offsetY=window.event.clientY - y;
	} else {
		offsetX = e.pageX - x;
		offsetY = e.pageY - y;
	}
}

function captureMouseDown() {
	mDown=true;
}

function captureMouseUp() {
	mDown = false;
}

function captureMouseMove(e) {
	if(!mDown)return;
	x = document.all?window.event.clientX - offsetX:e.pageX - offsetX;
	y = document.all?window.event.clientY - offsetY:e.pageY - offsetY;
	
	if(x<=-1 || x>=175 || y<=-1 || y >= 105)return;
	document.getElementById("marker").style.left = x + "px";	
	document.getElementById("marker").style.top = y + "px";

	x2 = parseInt(document.getElementById("marker").style.left);
	y2 = parseInt(document.getElementById("marker").style.top);
	x2 = (x2 - (x2*2))*2; 
	y2 = (y2 - (y2*2))*2;
	document.getElementById("largeImage").style.backgroundPosition = x2 + "px " + y2 + "px";
}

// Multiple onload function created by: Simon Willison
// http://simonwillison.net/2004/May/26/addLoadEvent/
function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent(function() {
  init();
});

CSS

Paste this code into your external CSS file or in the <style> section within the HEAD section of your HTML document.

#largeImage {
	position:relative;
	width:150px;
	height:100px;
	border:1px solid #000000;
	background-image:url("testz.gif");
	background-repeat:no-repeat;
	background-position:0px 0px;
}

#smallImage {
	position:relative;
	border:1px solid #000000;
	margin-top:5px;
	width:250px;
	height:155px;
}

#marker {
	position:absolute;
	top:0px;
	left:0px;
	border:1px solid #FF0000;
	width:75px;
	height:50px;
	cursor:pointer;
	background-image:url("tp.gif");
}

Head

Paste this code into the HEAD section of your HTML document.


<script type="text/javascript" src="imageNavigator.js"></script>

Body

Paste this code into the BODY section of your HTML document


<p>
Click and drag the red outlined square on the bottom photo to navigate the zoomed image.</p>
<div id="largeImage"></div>
<div id="smallImage">
<!--  This image must actually be double the size listed below  -->
  <img src="testz.gif" width="250" height="155">
	<div id="marker"></div>
</div>

Leave a Response

(1 comment)

The js image enlarging rectangle works great. I intend to use it to magnify my wife's art gallery page. Allowing viewers to "take a peek" at the art, without having to load an image which could be too large for some screen resolutions.[br /][br /]Thanks!

Charles Quinlan Aug 16, 2008

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