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Getting Started with the Virtual Earth Map ControlEric shares a very bare-bones example of adding the Virtual Earth control to a web page leaving it to the reader who can hack away with Javascript and html to create a more fully-fledged implementation.
Although I consider myself multi-lingual professional programmer, I must admit that when it comes to web development, there are some gaping holes in my reportoire including Java, consumption of web services in general, and notably for the experiment to be outlined here -- Javascript. Nonetheless, as any programmer can probably relate, picking up a new computer language is much easier than learning a new spoken language i.e. more like picking up a new Cannondale mountain bike (e.g. .NET) having mastered bike riding on a single-speed Huffy (C64 BASIC) as a kid. So what is this I am talking about? Microsoft has made available a Javascript API or interface for manipulating their new Virtual Earth service which includes vector map data and aerial photographs along with many other neat features including "Locate Me" using a database of Wi-fi MAC addresses and the incredibly useful Scratchpad. As we announced many months ago, Bill Gates reviewed the proposal for Virtual Earth during his most recent Think Week and fast-tracked the project.
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Let's start by taking a look at the Virtual Earth Javascript. What do you do with this? First, upload the script as a .js file on your web server. For instance, I have it loaded as http://www.ericfrost.com/virtual-earth/ve.js. The .js script will be referenced and called from your html file. A very basic html file which loads the map but does nothing else can be as simple as:
<html>
<head>
<script src="ve.js"></script>
<script>
function OnPageLoad()
{
map = new VE_MapControl(41.8, -88, 100, 'h', "relative", 1, 1, 400, 400);
document.body.appendChild(map.element);
}
</script>
</head>
<body onLoad="OnPageLoad()">
</body>
</html>
See example at http://www.ericfrost.com/virtual-earth/test1.html. That's it! How much easier could it be? From the .js script we can see the VE_MapControl parameters defined as: function VE_MapControl(latitude, longitude, zoomLevel, mapStyle, position, x, y, width, height) Valid mapStyle's include "a" for aerial, "r" for road, and "h" for hybrid. The position can be either "absolute" or "relative" and is in reference to the control's position in the browser. Amazingly, without any additional programming, you can already drag the map, pan with the arrow keys, and zoom in and out +/-. What do you want to see next? Play around with the parameters above and you can see them in action, for instance, I guessed and then fiddled with the lat/lon's to get the starting map to show Chicago. Someone who knows even rudimentary html and Javascript can take the example here and add buttons and drop-down's and checkboxes or whatever other cool html controls to modify the map object and change the map. We will revisit Virtual Earth development in future articles. Have you tried it on your web site? Please share in the forum section for this article and include the code!
Author: Eric Frost Email: website(AT)mp2kmag.com URL: http://www.mp2kmag.com Eric is Editor and Publisher of MP2K Magazine and is a part-time student in University of Chicago's evening MBA program. Eric recently finished the MP2Kmag Guide What's New in MapPoint 2004.
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