Google Image Charts API - How does it work?

I'm looking to create something loosely similar to the Google Image Charts API, where by I can construct a query string, and an image is returned.

For example:

http://chart.apis.google.com/chart?cht=p3&chs=550x250&chd=t:73,13,10,3,1&chco=80C65A,224499,FF0000&chl=Chocolate|Puff+Pastry|Cookies|Muffffffins|Gelato

I was开发者_开发问答 wondering, what would the best way to achieve this be? Does anybody have any info on how the Google Image Charts API works "under the hood" ?

Are there any libraries that provide dynamic image generation already?

You can use a server side script to read the query string parameters, generate the image and output the content using the image MIME type.

If you are on PHP, you can use an image library like GD to do this. More information here: http://us3.php.net/manual/en/book.image.php